texts: What weight and balance form should I use for my checkride?

texts: I am studying for private pilot checkride and saw this form in an Oral Exam. Can you tell me where I can get this form online? If not, is there a better form for expiration and W&B data?


texts: What is this stem on the underside of a Cessna 172R (1997)?

texts:
There is a stem that is located on the underside of the airplane between the drain valves for the fuel strainer and reservoir tank. It looks like a small stem that is protruding.

I have noticed it leaks a small amount of fuel (1 drip per 5 seconds). I am going to talk t my instructor about it but wanted to know what it was called. I am not seeing it in the fuel system diagram.

Updates:
I believe it is a part of the electric auxiliary fuel pump, but want any input.

The aircraft is a Cessna 172R made in 1997.

It is 100LL that is dripping.

Here is the fluid dripping.... Not water.


texts: A321 Two unsuccessful strong crosswind landing attempts. What was actually going on?

texts:
As a passenger on A321 I have recently experienced the following:

The plane took off in strong winds (25-30 knots) and then proceeded to the destination, which it reached in 45 minutes. At first attempt the plane touched the ground with its rear landing gear and then it immediately went full throttle and took off again. After making a circle, the situation repeated after which we flew back to the original port.

The pilot said: "I made the decision to go back because the wind is over 100 km/h, which is above this aircraft limits".

100 km/h is over 53 knots which is way above the limitations of A321.

Crosswind - Takeoff 29 kts
Crosswind - Landing 33 kts
Crosswind with Gusts 38 kts
Tailwind - Takeoff and Landing 10kts

My questions are:

Should the pilot have even attempted to land? Wasn't it too risky?
Should he have even taken off knowing about the weather conditions at the destination airport? How is this kind of decision normally made?
Since takeoff limits are lower than landing, was it safe take back off upon unsuccessful landing attempt? In other words if the winds are bad enough for landing do you want to take off rather than force the plane down and see what happens?


texts: Does it exist? Environmentally-friendly/safe fluorescent liquid to make sea crashes easier to find?

texts:
Has this been tried in aviation history?

To make airplane sea crashes easier to find, can we use a colored liquid that is lighter than water, environmentally-friendly and safe, with fluorescent properties so that if an airplane crashes into the ocean, this liquid would leak out and float to the surface. During the day, the color is noticeable by satellite and by night it glows.

Does something like this exist? Can it be easily implemented? Has it already been attempted?


texts: B-52s that are not in service demolished?

texts: Have all the B-52s that are no longer in service already been "guillotined," i.e. chopped in two to make them no longer flyable?


texts: What do the Thunderbirds pilots do when they can't fly?

texts:
I went to an airshow recently, and the Thunderbirds performed. However, by the time they finished the startup and flight check ceremonies, bad weather had rolled in. However, they did still taxi into position at the end of the runway to wait for the bad weather to blow over. About 45 minutes to an hour later, they decided visibility was to bad to fly, and they taxied back to the ramp.

My question is if there is a solitaire game built into the Thunderbird flight software or something to keep them from dying of boredom, or if they just stoically stare at the end of the runway.


texts:
When reading the specifications of a jet aircraft anywhere on the Internet, it usually states that its engine produces X pounds of "dry thrust".

Why is it called "Dry" Thrust? As opposed to what?


texts: Costa Rica landing in the news, concerns to be taken seriously?

texts:
A landing in Costa Rica has recently caught some attention in media, for example here.

A flight from Madrid to San Jose allegedly experienced difficult winds and the pilots changed the descent pattern accordingly.

They approached the runway at a very low altitude, scaring both passengers and people on the ground. And considering the footage available in the article, I don't blame them.

The authorities however claim that this was a normal and controlled landing, and that there are no limits how low the approach is allowed to be over the area close to the runway. They admitted, though: "Sure it could have been a little higher, but the altitude and angle of the plane was fine."

Are the authorities right about this, or should the media's, the passengers' and the locals' concerns be taken seriously?


texts: Typical burner/combustor dimensions of a jet engine

texts:
I know that sounds very generic but lets say for a common engine of a passenger airplane. What could be the typical dimensions for the burner part. I can't find anything online.

Thanks.


texts:
Does a subsequent crossing restriction supersede earlier crossing restrictions?

Here's an example.

While flying the MIP4 arrival into KLGA, you receive the expected instruction to cross MARRC at FL180. Before reaching MARRC, you receive the instruction to cross BILEY at 13,000. These fixes being expected is not material to the example. The question is, when given the subsequent instruction to cross BILEY at 13,000, does this supersede the instruction to cross MARRC at FL180.

If possible, please cite answers in 14 CFR, AIM, or another FAA source.


texts: For flight planning must the forecast weather be above minima one hour before, after or at ETA? (EU-OPS)

texts:
Citing EU-OPS:

  CAT.OP.MPA.185 Planning minima for IFR flights — aeroplanes

  (a) Planning minima for a take-off alternate aerodrome

    The operator shall only select an aerodrome as a take-off alternate aerodrome when the appropriate weather reports and/or
    forecasts indicate that, during a period commencing one hour before
    and ending one hour after the estimated time of arrival at the
    aerodrome, the weather conditions will be at or above the applicable
    landing minima specified in accordance with CAT.OP.MPA.110. The
    ceiling shall be taken into account when the only approach operations
    available are non-precision approaches (NPA) and/or circling
    operations. Any limitation related to OEI operations shall be taken
    into account.

  (b) Planning minima for a destination aerodrome other than an isolated destination aerodrome

    The operator shall only select the
    destination aerodrome when:

      (1) the appropriate weather reports and/or
      forecasts indicate that, during a period commencing one hour before
      and ending one hour after the estimated time of arrival at the
      aerodrome, the weather conditions will be at or above the applicable
      planning minima as follows:

        (i) RVR/visibility (VIS) specified in accordance with CAT.OP.MPA.110; and

        (ii) for an NPA or a circling operation, the ceiling at or above MDH;

      or

      (2) two destination alternate aerodromes are selected.

  (c) Planning minima for a destination alternate aerodrome, isolated aerodrome, fuel en-route alternate (fuel ERA) aerodrome, en-route alternate (ERA) aerodrome

    The operator shall only select an
    aerodrome for one of these purposes when the appropriate weather
    reports and/or forecasts indicate that, during a period commencing one
    hour before and ending one hour after the estimated time of arrival at
    the aerodrome, the weather conditions will be at or above the planning
    minima in Table 1.

  [...]

On the other hand:

  CAT.OP.MPA.245 Meteorological conditions — all aircraft

  (a) On IFR flights the commander shall only:

    (1) commence take-off; or

    (2) continue beyond the point from which a revised ATS flight plan
    applies in the event of inflight replanning,

  when information is
  available indicating that the expected weather conditions, at the time
  of arrival, at the destination and/or required alternate aerodrome(s)
  are at or above the planning minima.

  (b) On IFR flights, the commander shall only continue towards the
  planned destination aerodrome when the latest information available
  indicates that, at the expected time of arrival, the weather
  conditions at the destination, or at least one destination alternate
  aerodrome, are at or above the applicable aerodrome operating minima.

  (c) On VFR flights, the commander shall only commence take-off when
  the appropriate weather reports and/or forecasts indicate that the
  meteorological conditions along the part of the route to be flown
  under VFR will, at the appropriate time, be at or above the VFR limits

  CAT.OP.MPA.246 Meteorological conditions — aeroplanes

  In addition to CAT.OP.MPA.245, on IFR flights with aeroplanes, the commander shall only continue beyond:

    (a) the decision point when using the reduced contingency fuel (RCF)
    procedure;

    or

    (b) the pre-determined point when using the pre-determined point (PDP)
    procedure,

  when information is available indicating that the expected
  weather conditions, at the time of arrival, at the destination and/or
  required alternate aerodrome(s) are at or above the applicable
  aerodrome operating minima.

So, should a commander of an operator's flight opt to commence a flight when the forecast at the ETA is above the minima, or the forecast needs to be above the minima for the period from one hour before the ETA till one hour after the ETA?


texts: Why was the Tu-104 so prone to navball-disabling electrical power failures?

texts:
Of the (rather numerous) accidents involving the Tu-104, several were either caused or aggravated by major electrical failures, which disabled the aircraft's navballs, which caused the pilots to become spatially disoriented, which caused (or contributed to) a loss of control, which caused the aircraft to crash:

SU4 (15 August 1958) - en route from Khabarovsk to Irkutsk, the aircraft climbed too high while attempting to avoid storms ahead; recovery from the resulting stall was rendered impossible by "...disorientation of the crew, from accompanied failure of the artificial horizons".
SU3932 (30 September 1973) - shortly after takeoff from Sverdlovsk-Koltsovo, "[t]he aircraft crashed due to incorrect indications by the main artificial horizon and the compass system, caused by a failure of the electrical supply, resulting in spatial disorientation of the pilots."
SU964 (13 October 1973) - while on approach to Moscow-Domodedovo, the aircraft banked excessively far to the left, entered a spin, and crashed; "[t]he investigation concluded that after the first right turn executed by the aircraft (in which the bank exceeded 40°), multiple navigation instruments including the compass and artificial horizon failed. Combined with the poor visibility at the airport, the crew lost spatial orientation and were unable to see any landmarks to determine their position. When the plane banked slightly to the right, the pilots corrected the right bank only to put the plane into a sharp left bank that reached 70°, causing the crash."1
SU2415 (28 November 1976) - when making a right turn during climbout from Moscow-Sheremetyevo, the aircraft continued to turn past the assigned heading, rolled onto its side, and dove into the ground; "...among the causes of the crash included failure of the artificial horizon, poor visibility from the cockpit, and lack of warnings indicating the failure of the artificial horizon."

What made the Tu-104 so prone to these catastrophic electrical failures?

1: With 122 fatalities, this is still the worst Tu-104 crash to date.


texts: Is a turbocharged piston aircraft the same thing as turboprop?

texts: Simple question, and I've always assumed that they are the same thing, but I'd like feedback from someone who knows more than me :)


texts: What is the minimum distance between two civil airplanes parked in a hangar?

texts: When parking two airplanes in the hangar, what is minimum safe distance between them?


texts: What is "(CFMCC)" on an ILS approach chart?

texts:
I'm studying the ILS or LOC RWY 3 approach chart for KMKC. I'm trying to figure out what "(CMFCC)" at the runway means.

Is it a computer navigation aid?


texts: What is the difference between the airspace's classes (for non-pilots)?

texts:
When I'm reading about aviation, it's very common to see references to Class B or Class C airspace and airports.

What are the different classes and what are the differences between them?


texts:
Why are passengers requested to close their window blinds during a night-time takeoff?

I understand why they are asked to open them during day-time take-offs and landings - probably because rescue teams can look inside in the case of a crash. But what´s the point in closing them at night?

The only reason I can think of is that people might mistake the cabin lights for landing lights, hence misjudging the planes orientation. Still, it is very difficult to mistake a row of cabin lights for landing lights?


texts: What materials make up most of the weight of an aircraft?

texts: What are the material types account for most of the empty weight of an airplane (Boeing 747), besides aluminum or its alloys used in fuselage?


texts: Can pilots choose runway and landing direction?

texts:
Pilots normally receive landing clearance for a specific runway assigned by ATC. Absent an emergency, can pilots of commercial flights (depending on the wind conditions for example) choose

a different runway
the landing direction for this runway
or both ?

If no, why not ?
If yes, (and still assuming nothing is wrong with the aircraft) how does the pilot get his wish ? Can (s)he ..

simply choose (i.e. just communicate the choice to ATC, which has to accept it) ?
request it / ask for it (but ATC has the final say) ?
insist on it ? (analogous to "telling ATC you are altering heading for weather")

In the last 2 cases, does the pilot need to name a specific reason ?


texts: What phenomenon causes the increase of drag with rain?

texts:
I know that rain generally worsens the aerodynamic propeties of an aircraft.

I'm wondering what processes cause the increase in drag.

I'm mostly interested in General Aviation, thus relatively low speed and low altitudes.

Several things I can imagine, although the effects might be small:

The water in the air makes it heavier, increasing the effective value of the air density, $\rho$
Rain might lower the temperature, again having an effect on $\rho$
Rain drops on the wing might cause earlier transition on the wing, increasing  drag.

I hope somebody can clarify what magnitude these effects have, and if there are any more effects that cause an increase in drag when flying in the rain.


texts: Do check rides completed by part 141 schools with self-examining authority count like normal check rides for CFI renewal and gold seal?

texts:
Some schools have self-examining authority issued by the FAA.

Do check rides completed in this manner count the same way as a standard check ride for the purpose of CFI renewal and gold seal applications?


texts: How much runway is needed for comfortable operations in a PC-9?

texts:
I am familiar with simple single engine props and twins and am thinking of moving up to turboprops like a Soccata TBM 700 or Pilatus PC-9.

How much runway do aircraft like these need to operate comfortably? (think grass strips with trees at the ends). By "comfortably" I am not talking about test pilots in perfect conditions. I am talking an amateur pilot on a windy, rainy day with enough runway that he won't be shaving bird nests out of the trees on takeoff.


texts: Can ADS-B DF-17 messages with a non-zero remainder after CRC check be used?

texts:
For fun I've been using an AirSPy SDR (Software Defined Radio) to receive and decode ADS-B packets, primarily DF-11 and DF-17 messages.

The code is written in C++ and works reasonably well. It performs IQ processing / demodulation, packet extraction, CRC checking etc. As its output it generates AVR formatted message strings that are then served via a Listen Socket / Socket based interface. I then use Virtual Radar as a client to decode and display the data.

With regard to the DF-17 and DF-11 packets, I'm currently only forwarding the ones that have an Interrogator ID of zero, the so called "unsolicited squitters". i.e. Complete packets that have a zero remainder after CRCing.

I also receive / decode plenty of packets that have non-zero Interrogator IDs.

Can I use these for anything useful?

In other words, could I extract any useful information, positions, velocities etc. If so I could then re-write them as unsolicited DF-17 messages and pass them to Virtual Radar.

I am researching this to the best of my ability, but currently drowning in specs and documentation as there appears to be so much of it!

Apologies if I've miss used any of the jargon, I'm only a week into my project.


texts: Is a releasable locator beacon (ELT) required for aircraft carrying passengers over a water area?

texts:
Is an Emergency locator transmitter - ELT required on any type of aircraft carrying passengers over water? Does it need to be fitted with an hydrostatic release unit so that it doesn't sink with the aircraft?

If they don't carry a releasable ELT, how are aircraft planned to be located after an accident over the ocean?

References to regulatory documentation definitely a plus (e.g. for the US, or for island countries like Australia or New Zealand).


texts: Can gusts be reported as lower than wind speed?

texts:
KADS 072350Z 31030G20KT 13SM SKC 24/02 A2980

I’ve never seen a negative gust factor before. Is that a real thing (and if so, what does it mean), or did someone just make a typo?


texts: How common are diversions to high-latitude airports for intercontinental flights?

texts:
Comments to this question point out that diversions and emergency landings are not the same.

Many flights between Europe and North-America pass over (very) high latitudes and cold climates such as Greenland and northern Canada.  How common are diversions such as this one?  Or, more specifically, out of all scheduled passenger flights between Europe and North America, how many are diverted to high latitude airports?  For the purpose of this question, I am considering incidents where passengers were forced to leave the plane and change to one or more other planes, rather than a flight that lands and takes off again continuing to its final destination without passengers deplaning.


texts: Where did  the phrase  " pan pan"  when declaring an emergency originate?


texts: What's the difference between FMS and FMC?

texts:
What's the difference between FMS (Flight management System), and FMC (Flight management computer)?

Can the flight management computer be thought of as what's manipulating the input information from the performance/navigation databases, and the FMS as being what actually provides the information?

I understand the information that's involved with the system, I'm just trying to define the difference based off an analogy of sorts.


texts:
Even though it is nine years since then, I can still clearly recall my return flight from London Luton to Katowice (Poland), that I took on July 31, 2006 evening. There were a huge, strong storm front coming to Poland (ten days of extremely high warmth followed by ten days of an unusually high raining and really strong stroms, that started on August 1, 2006 in Poland), that we hit somewhere over Germany (hit or flown somewhere around / near it).

I was then and I am now a layman in aviation, so my description and terms used my not be correct, however I recall, that it was really a bumpy ride. Plane was falling down (loosing 100 ft or so) and trying to  go back to previous altitude etc.

At some point, one of a pilots informed everyone on board, that they'll be dimming all the cabin lights, because "they need more power to the engines to go through this strom". And soon after that, they really did that and for about 10-20 minutes we were flying in a very limited cabin lightning.

Is this true, what we have heard nine years ago? Were cabin lights really consuming that much power back in 2006? Or was that just a strange way pilots wanted us to get a little bit more scared?

I was flying with Wizzair, so I assume, that it was A320. There is a similar answer on similar matter, but it says about LED-based cabin lights system and I can hardly believe, they were introduced to "cheap" Wizzair's A320s back in 2006.

But, even assuming, that our plane was fitted with a "typical" lights, much more energy consuming that LEDs, it is really hard for me to believe, that cutting on cabin lights could bring any noticeable power to airplane's engines. Correct me, if I'm wrong.


texts: How does Mach number of Jet engine vary with respect to Compression Ratio?

texts:
How does the performance of jet engine vary with Compression ratio.
What are the variables that affect the Mach number of Jet engine.


texts: Does Russia still use a Snowtam to report normative brake friction?

texts: Does Russia still use the normative (Russian) brake friction when reporting Snowtams for their airports? What about former Soviet (CIS) countries?


texts: Do any flight simulators go completely inverted?

texts: From the pictures I have seen of airline simulators, it looks like the range of motion is limited to somewhat level flight. Are there any flight simulators, possibly military trainers, that can do a complete barrel roll?


texts: Why are there no supersonic propellor driven aircraft?

texts:
Pretty self explained in the title.

Yes, I realize there is no widespread demand for them; this is not what I'm looking for in an answer.

I'm looking for an answer that covers more why they can't be built (or aren't practical to). I know that jet engines may generally be better, but I've recently been doing reading on aircraft like the Thunderscreech and it's made me curious why exactly it won't work.


texts:
What are the ICAO equipment codes for those Garmin units?

Garmin G500 / 750 / 650 WAAS navigators?


texts: Why did the design of the Boeing 247's cockpit windows change for some models?

texts:
Have a look at this article on a famed example of the 247.
The image at the top is the aircraft during its flights with the RAF, likely some time in 1944. Note the reverse-slope windows that are a hallmark of the 247.
Now look at the other aircraft in the same article. They have conventional style slope-down windows. Those two images are from before 1944, one in the 30s and the second around 41/42.
Does anyone know what's going on here? Were certain batches one way or the other?


texts: Which type of control gives a more agile missile, tail or canard?

texts: I read somewhere (sorry don't remember where) that canards controls for missiles are more effective than tail controls.  Is this true, and if so, why?


texts: Aerodynamic Pressure Loads in FEA of Lifting Surfaces - Query

texts:
Let me give a brief summary of the process involved in the FEA of lifting surfaces with the wing as an example:
1. The wing is modelled as a hollow surface body in Ansys, meaning only the exterior aerodynamic surface is specified.
2. Internal structure made of composites is modelled next.
3. Aerodynamics loads and Boundary conditions (fixed edge at the root of the wing) are specified.
4. The solution is obtained in terms of displacements, stresses and failure criteria etc.

As part of Step-3, aerodynamic loads are generated in the form of Cp values (Coefficient of Pressure) at discrete points on the exterior surfaces of the wing. This data is generated from XFLR5.
Cp values are converted into pressure values and applied on the exterior surfaces of the wing. To do the same, the following formula is used:

Pressure values obtained from the LHS of the above expression are applied over the exterior surfaces of the wing. FEA process is completed and the solution is obtained.

FEA predicts that the wing cross-section is unable to maintain its airfoil shape and the wing cross-section essentially gets "crushed"'.

Observe the crushing of the wing cross section in this figure where the top surface and bottom surface come close to each other and airfoil geometry is completely lost

However, it finally struck me that there has to be an internal air pressure that will support the cross section from the inside as what happens with hollow structures on earth, eg. a hollow can be placed on the ground doesn't get crushed into itself since the external and internal pressures cancel each other out.

Hence, we should not be using absolute pressure but rather gauge pressure (difference in external and internal pressure) should be used. Otherwise, it essentially means that there is a vacuum on the inside and air pressure on the outside.

Once this change was made, we no longer observe the "crushing" effect.

Finally, we still want to be sure if the internal air pressure would be equal to the static pressure at that altitude as has been assumed in the usage of gauge pressure.
Our assumption is that the pressure inside the wing body would be equal to the static air pressure at that altitude from thermodynamic relations even if the wing is completely sealed. IS THIS ASSUMPTION CORRECT? ANY SUGGESTIONS WOULD BE HELPFUL?


texts: How much does a Black Box Underwater Locator Beacon (ULB) cost?

texts:
I'm curious if anybody can provide a rough price estimate for a commercial aviation ULB like those used on Black Boxes.

Area of interest: Europe i.e. Euros, EASA CS-25.

(For instance the RJI ULB-362 or the Dukane DK-120, but any equivalent is good)


texts: Is tungsten a good metal for jet engines, besides the weight penalty?

texts:
Right now, the hottest part of jet engines are made from a steel-nickel alloy. Is tungsten a better choice?

Pure tungsten has the highest melting point and highest tensile strength of any other pure metal. Presumably you could make it hollow and use the same cooling fluid to prevent overheating. For this same reason I am not sure if the weight penalty is really that big. I don't think the turbine blades make up a really big part of total engine weight.

(I don't know how well it resists oxidizing at high temperatures. I don't know how it might change with adding a little carbon or steel or nickel. But presumably this is not a drawback because I've read about rocket engine nozzles using tungsten: link. If it doesn't oxidize or corrode there, I can't imagine why it would do so in a jet engine.)

Another way of asking this question: Does tungsten in the hottest part of jet engines have any major drawbacks besides weight and cost?


texts: Just the basic question that every aviation enthusiast must be curious about: exactly how does a wing generate lift?


texts: What are the labels for this aircraft's JSON?

texts:
Can someone please help me identify the labels associated with the below JSON?

The data comes from FlightRadar24

c5cded9":[
          "06A0F8",
          51.3056,
          6.4601,
          283,
          43000,
          459,
          "3245",
          "F-EDDK1",
          "A359",
          "A7-ALD",
          1486231556,
          "DOH",
          "LHR",
          "QR1",
          0,
          64,
          "QTR1",
          0
]

I get that 51.3056 & 6.4601 are the latitude and longitude. I also get that 43000 is the altitude and 1486231556 is a timestamp, but I do not know what the others should be...

For example, LHR I guess is London Heathrow, but is what is the official term?

I'd like official terms to match the JSON.

I want to do some data visualizations with the aircraft data.


texts: What are these teardrop shaped thingamabobs on the bottom of the Panavia Tornado?

texts:
What are these two teardrop shaped thingamabobs on the bottom of the Panavia tornado?

They could be hardpoints but I haven't found any photos where anything would have been mounted there. They don't look like hatches. And they don't seem to be any kind of vortex generators either. What purpose do they serve?

Click to view full-sized image:

Here's a few closer images:


texts: Where are jack points typically located on an aircraft?

texts:
I realised that full gear swing tests require an aircraft to be fully jacked up; and I think it would make sense to locate the jack points close to the landing gears themselves, on the same load-bearing structures (e.g., main wing spar), since those structures are already designed to support the weight of the aircraft.

Is that generally the case, and are there considerations where designers would locate the jack points elsewhere (and presumably have to specially reinforce these other locations)?


texts:
I notice in a website taling about jetstream
https://www.weather.gov/jetstream/jet

It says:

  The winds blow from west to east in jet streams but the flow often shifts
  to the north and south. Jet streams follow the boundaries between hot
  and cold air. Since these hot and cold air boundaries are most
  pronounced in winter, jet streams are the strongest for both the
  northern and southern hemisphere winters.

Why these hot and cold air boundaries are most pronounced in winter? I dont get it.


texts: How are the 737’s elevator and aileron cables attached to their control tabs without impeding the control surfaces’ motion under hydraulic power?

texts:
The 737 (all versions thereof) is one of the few jetliners still in production to have any manual-reversion capability for its flight controls in the event of the loss of all hydraulic systems.  If hydraulic pressure is lost in both the A and B hydraulic systems, control tabs on the elevators and ailerons unlock, and the elevator and aileron control cables, which are directly attached to these tabs, deflect them to produce aerodynamic forces that move the elevators and ailerons in the desired direction.1  When hydraulic pressure is available in either of the two primary systems, the control tabs are locked to their respective control surfaces and move with them.
Thus, the control tabs - which are still attached to the control cables even when locked to the elevators and ailerons under hydraulic power - deflect in the opposite direction when the flight controls are being moved hydraulically compared to when in manual-reversion flight.  For instance, when a pilot commands up elevator in hydraulic flight, the elevator actuators move the trailing edge of the elevators, and of their control tabs, upwards, even as the control cables themselves are trying to pull the trailing edges of the elevator control tabs downwards (as would be necessary when commanding up elevator in manual-reversion flight).  How does the 737’s flight-control system prevent the forces generated by the hydraulic flight-control actuators from feeding back through the control cables (via their attachments to the elevator and aileron control tabs) and forcing the pilots’ yokes in the direction opposite their control inputs, or, alternatively, the forces exerted directly by the control cables from impeding the control surfaces’ motion when under hydraulic power?

1: Not all of the 737’s control surfaces have provisions for manual control; the spoilerons (which deflect asymmetrically to assist the ailerons in rolling the aircraft) are inoperative if the A and B hydraulic systems both fail, while the rudder (which provides yaw control independent of roll) can be powered by the third, standby hydraulic system2 if both the A and B systems fail, but does not have manual-reversion capability in the event of a failure of all three hydraulic systems.
2: The standby hydraulic system (which can provide hydraulic power to move the rudder, actuate the thrust reversers, and - if the ALTERNATE FLAPS switch is engaged - extend the leading-edge high-lift devices) is normally unpressurised, but can be manually activated by the pilots (and activates automatically in the event of a hydraulic failure during critical phases of takeoff and landing); this is generally done in the event of a failure of one or both main hydraulic systems, but the standby system can be engaged even if both the A and B systems are fully operational (useful for clearing some types of rudder jams, although less so nowadays than was the case with the 737’s pre-2008 rudder-control system).


texts: What is the effect of earth's speed on flight?

texts: What happens if an object (plane or space ship) travels at a speed less than that of earth rotation?


texts: LPV/LP approach (RNAV with WAAS): What is actually the "channel number"?

texts:
Curious about the answer to this question: How may I verify WAAS channel number on G1000?, I just found that SBAS/WAAS use in aviation seems to be poorly explained.

In particular the WAAS "channel number" seems to suggest that some radio frequency is associated with a given WAAS approach.

(Image taken from the linked question)

I think the WAAS service is provided by only two geosynchronous satellites, each one broadcasting on the same frequency the corrections for the whole US area. So there is no need to tune the WAAS receiver based on the airport location, the runway number, or the LPV identifier.

So the question: Are these 3 informations strictly redundant (maybe not taking into account version numbers), and they exist only for triple-check purpose?

LPV approach name: RNAV (GPS) Y RWY 36L,
WAAS channel number: WAAS CH 56613,
WAAS approach ID (aka reference path identifier): W36A

Could you confirm that selecting any of these values on the avionics will only change what is retrieved from the local navigation database, and will not impact the GPS/WAAS data received?

Note: I could understand if the approach were LAAS/GBAS (local ground-based) instead of SBAS.


texts: What would be the lift formula for straight wings?

texts: I have been trying to estimate the lift calculation for a straight wing. The previous project I worked on was a swept wing. But this is a straight wing. I would like to to get the stall speed so I need the Clmax formula. What would the lift formula for this type of wing be?


texts: What things do you consider when choosing a fixed base operator (FBO)?

texts:
I'm working on some marketing for a regional FBO and while I'm an aviation aficionado, I'm neither a pilot or deeply involved in the aviation industry.

I'd love your input on how you research and choose an FBO while doing your flight planning…

As a pilot what are your primary considerations when choosing an FBO? Fuel cost, amenities, local knowledge, other things entirely?
What things do you look at as distinguishing factors between competitors?
Are there certain things that you consider mandatory from an FBO?
What information do you want to "know before you go"?
What online resources do you personally use when doing your flight planning and/or researching FBO's?
Have you had an extremely positive (or terrible) experience with an FBO, so that I can research them?

I'll also note that this particular FBO is located in a fairly rural, yet growing region of the Western United States.

Look forward to your input and responses!


texts: Is alpha induced angle real on 3D wing or just math concept?

texts:
Does alpha induced angle/"effective airflow" really exist in real life on 3D wing or this is just mathematical concept for calculate induced drag?

(same as lifting line theory-circulation theory is just math concept for calcualte lift ,but everyone knows that airflow dont move around wing in circle...)

Question is ,if I put AoA-sensor infront of leading edge at same position at 2D and 3D wing,will be values different or equal?

(theory tell us that angle (A) at my picture below must be less on 3D wing than 2D wing...)

(in my home made wind tunnel ,I cant see difference when I put visual AoA indicator infront of leading edge at  2D compare to  3D wing..so this is reason why I ask is this real thing(maybe angle is too small to see) or just math concept...all this mess with questions about induced drag on this forum ,starts when I do this experiments..)

here is exampels of visual AoA indicators:video 1     video 2


texts: What does leading edge radius mean amongst these parameters of a st cyr 24 airfoil?


texts: Why does the B-52 outboard engine nacelle have a sharp change in shape?

texts: The outboard engine nacelle of a B-52 appears to have a change of shape too extreme for just blending to the center-line of the engine pod. Why is the B-52 outboard engine nacelle shaped the way it is?


texts:
Was listening to one of Petra's old songs, when I noted the aircraft in the cover image. I tried searching on the net, but couldn't find anything.
It appears to be a pusher aircraft, with a four blade propeller.. that's all I could gather from the image. There are markings "ANG" (?) but I do not know how helpful that is.
This is from Petra's album titled "Beyond Belief".


texts: Why are all engines identical in typical commercial airplanes?

texts:
I come from the IT world where redundancy is in place to cover several cases, among other:

a statistical failure of a device (so we use more of them expecting that the event is independent)
a rogue usage of a device (hacking into it though a vulnerability)
a specific context where a bug is triggered

In order to account for the last two ones, redundancy is sometimes (or usually - depends on the criticality of the system) done with different devices (form different vendors). This is typically the case with firewalls, for instance.

I was wondering why this isn't the case with aircraft engines?

It would be "easy" with planes having four engines (so two of each kind), somehow less "easy" with two engines (where the differences between their regimes would need to be compensated - the pilot states that they want 80% of power, which, in the specific conditions they are in, means 78% for the left engine and 83% for the right one).

Having two redundant engines which are equally susceptible to be impacted by, say, ashes is probably not interesting, compared to having two different ones which would each have its strong and weak points (but different between the two)

Note 1: "easy" above is used as a placeholder only. I am aware that aircraft software and hardware is complicated, I mainly wanted to highlight the difference between 2 and 4 engines. Having two firewalls is a simple task compared to that.

Note 2: it may be that engine failure is not a big deal, statistically speaking compared to other issues (or in an absolute sense), and therefore the extra maintenance, structural compensations because of the differences etc. are not worth it. Thanks for pointing this out if this is the case


texts: Is this XKCD comic list about autogyro features accurate?

texts:
I recently came across this XKCD comic which gives you a number of facts about autogyros:

Image is copyright XKCD, licensed under CC 2.5 BY-NC

I'm not sure if this is satirical or really drawing attention to some very odd real-world facts, or a mix of the two.

Statements:

  Looks like a helicopter, but is nothing like a helicopter
  Flies like a plane but is nothing like a plane
  Cheap
  Needs a runway to take off, but not a long one
  Can land vertically
  Cannot hover
  Big blade on top is not powered […]
  Never stalls
  Sort of like a powered parachute
  […] usually homemade.
  Common in Europe. (I'm fairly sure I've never seen one in the UK)
  Can often be flown without a licence

Are these things all true? How do they actually work?


texts: What is the purpose of a reverse-flow orientation for turbo-prop aircraft?

texts:
If I decide to utilize a PT6 (ignoring for now the cornucopia of variants) as the turbine engine I will be using on my newly designed turbo-prop aircraft, do I then decide how I will orient the engine or is the this something that is engineered into the engine and thus a consideration when deciding which we choose?

Source (adapted)

What compels an aircraft design team to utilize a reverse-flow (turbine ahead) turbine engine orientation? Is the reverse-flow a design of the engine, or maybe an option?

What are the benefits/ drawbacks of reverse-flow designs to the design engineers, mechanics, flight crew, and/or airlines?


texts: Why does Boeing 247D have reverse slope windows when they were removed from the D models?

texts:
Have a look at this article on a famed example of the 247D, DZ203, the first aircraft to make a completely blind landing. The first image is the aircraft during its flights with the RAF, which places it after 1942. Note the reverse-slope windows that are a hallmark of the early 247's.
However, this is a D model, and the D model of the 247 is noted as having had these removed and replaced with normal slope-down windows. This can be seen in the images of the other 247Ds on the same page, which were produced in the same batch of aircraft.
Does anyone know what's going on here? Were certain batches one way or the other?
NOTE: No, this is NOT a dup. The original answer from a while back states that all 247D's had forward slope windows, but this example clearly does not.


texts: Can I get an EASA Class 1 medical if I have monocular vision?

texts:
I have monocular vision (amblyopia). In the USA I can get an FAA first class medical via a SODA waiver. Can I get an EASA Class 1 Medical issued with the same monocular problem? I would be applying for a medical in Ireland.

If I absolutely can’t get an EASA Class 1 medical, then will European airlines hire ATPs with a US FAA first class medical, or do EU airlines all require EASA Class 1 Medicals?


texts: Cascading Wings: Do they really increase lift by 300%?

texts:
Cascading Wings for Ultralights: Do they really increase lift by 333%?!?!?

The classic NACA 650-18 airfoil has a Clmax of 1.5 according to airfoiltools.com ( a modified 650-18 is used on the Zenith 701).

Add non-slatted flaps, and the Clmax jumps to about 2.2.

What if one arranges the wing in a cascading fashion as shown below? Javafoil shows the Clmax jumping to 5, that’s an increase of 333% over the plain wing!!!

Not by just adding the same planform, but dividing the original chord by 4, so the a/r ratio is 4 times the original....

So that the quadplane is 400% more efficient than the original monowing, less a quadplane inefficiency of about 50%, so that the quadplane is still 200% more efficient than the monowing(maybe).

This probably only works ( if at all ) for very slow speeds (Re 300-800k) where the form drag and induced drag is very low.

I understand Javafoil uses Xfoil, which I’m told is a robust airfoil performance prediction program and is accurate up to an AOA of +/-20 deg.

Alternately, I’m told the VLM method (XLFR) is good up to only a Clmax of 1.5, +/- 20 deg.

So…. the million dollar question is… is a Clmax of 5 realistic, or is this beyond the scope of Javafoil/xfoil, even though the AOA is only about 8 deg….?

Ultralight Design Data:

See charts and tables below.

Flaps: 20% chord, 50 deg deflection

Wing Loading:51kg/m>2

Aspect Ratio: 7

Atmospheric conditions: Standard

Wing configuration: see chart below

Gap(vertical): 50%

Stagger(horizontal): -10%

Therefore biplane ( not multiplane) lift efficiency as per the table below should be: .26/.34=76% efficiency vs mono wing (Is this correct?) ( ignore the big green arrow, it's from the source I found the table)

Reynolds #: 880k

or......

is there a glitch in the software as per the comment below:

and the Clmax is about: climax 5 / 4 wings = 1.25

given the Clmax for a monowing is 2.2, and a biplane at 50% gap is 22% less efficient, a quadplane with 4 wings can easily be 40-50% less efficient, giving a clmax of about 1.3, which is close to the clmax of 1.25 above.

So what is the likely Clmax, 5 or 1.25?


texts:
I noticed that the saftey cards on a recent domestic US flight were the "overwater" version. Two questions about this:

What qualifies as "overwater"? Is there an official (i.e., FAA) definition?
Do airlines really have certain aircraft with booklets that aren't "overwater"? Are they prevented from flying certain routes without the right safety booklets?


texts: Is responding to an internet forum post looking for a scenic flight "holding out"?

texts: Suppose I'm a private pilot and see a post in a closed group on Facebook where someone is looking for a scenic flight around my area. If I offer them a flight with me, sharing costs equally, am I holding out? Does it matter if I know the person vs. if I don't? Thanks!


texts: Can air-to-air refueling be done in compliance with the FAR's?

texts:
I am wondering if any FAR's would prohibit the air-to-air refueling of two civilian aircraft in the US. In our use case, the receiving aircraft would be custom-built, and it would receive fuel pumped from a portable tank temporarily installed in a Quest Kodiak turboprop with the cargo door taken off.
There's the umbrella "don't be reckless" rule, but if it's done in a controlled way, what laws might stop us?


texts: Is there much turbulence in the Doldrums?

texts: A place over the equator called the Doldrums are know for the severe lack of sailing winds. In the atmosphere above it is there any presence of turbulence anywhere? Where would the least year round turbulence be found?


texts: On a ducted propeller, how does duct length affect thrust?

texts:
So if we are looking at an aircraft with a ducted propeller (or a high bypass turbofan engine), does it matter how long the duct is? As an extreme example, would having a duct that extends 100 feet behind the prop give any added thrust (let's ignore drag/weight effects of the 100 foot duct)? Because from my understanding, thrust is applied directly at the propeller, so it shouldn't matter how long the duct is just as long as it prevents tip vortex effects.

So as a follow up, why do most high bypass turbofan engines have their bypass duct extend back to where the engine core ends?


texts: Converting lat long & altitude into a line of sight target?

texts: I want to design a long-range ADS-B receiver with a directional antenna (like a Yagi), but in order to maximize its range, I'll need to orient the antenna towards a target (plane) based on existing data from external sources like FR24. I can easily find latitude longitude and altitude data for planes, but how do I convert these values into polar and azimuth angles that I can orient my antenna towards? Essentially, I need to calculate the line of sight my antenna needs to point at in order to make contact with the plane with the antenna's main radiation lobe. Does anyone know I could go about doing this?


texts: In an Airbus A320, when alpha protection is active, is pitch protection no longer available?

texts:
The A320 FCOM chapter 27 flight controls, normal law, protections, shows a diagram how the sidestick input is used when protections are active. When high angle of attack protection is active the side stick controls angle of attack (alpha protection to alpha max), so far so good.
In several places throughout the FCOM and that diagram I talked about Airbus states that the alpha protection has the highest priority.
Does this mean when alpha protection is active that pitch protection is no longer available? It makes sense that the nose of the aircraft is allowed to drop below the normally protected minimum of 15 degrees but is the maximum pitch of 30 degrees (or 25 depending on config and airspeed I think) still protected?
When alpha prot is active is it possible to pitch up to more than the maximum pitch limit? The diagram would suggest yes.


texts: Which are the requirements for the water supply on board?

texts: Which are the requirements for the water supply on board of a commercial airplane? I know that there are minumum mandatory requirements, but I don't know where to find them and how they can change with the category of the aircraft. Surely there are different requirements from a small turboprop without a toilet to a A320.


texts: Is the quickest way to reverse direction by turning horizontally or vertically?

texts:
Assume my aircraft is flying with Mach 2 and I want to quickly change my direction of travel 180°.

So for a horizontal turn flight I found the formula: angular velocity = g* sqrt(n²-1) / v
For a looping flight I found the formula: angular velocity = g* (n-1) / v

So for the same load factor n my aircraft should do a faster turn with maneuver number 1. Since my angular velocity is higher.
Are my considerations right?
Also, according to both formulas above the ability to do a quick turn around is (let us neglect velocity) only affected by load factor. So my LIFT FORCE (no matter where it acts on my aircraft) is the limiting factor, nothing else. Is that correct? (And lift force is limited for many other reasons...)
Because I had the considerations: if I let the lift force act far away from the center of gravity, I will get a big lever arm and this way a big moment which should create a higher angular velocity. So lift should not be responsible for a quick turn but the lever arm?


texts: Can I do a VFR climb-out on IFR flight plan?

texts:
Let’s suppose I wish to fly an IFR flight from KTUS (Tucson International Airport) to KFST (Fort Stockton-Pecos) for example. Given the surrounding terrain there is of course an ODP that reads as follows:

  DEPARTURE PROCEDURE: Rwys 3, 29L/R, climbing right turn direct to TUS
  VORTAC …
  Rwy 21, climbing left turn direct to TUS VORTAC …
  Rwy 11L/R, climb heading 123° to 4000 then climbing left turn direct TUS
  VORTAC …
  ... Climb in TUS VORTAC holding pattern (hold NW, right
  turns, 128° inbound) to 9000 before proceeding on course.

That’s a pretty long departure procedure especially with the temperatures this time of year but it makes perfect sense due to the terrain.

Now since I expect the weather to be CAVOK until the MSA, I would prefer to do a VFR climb-out. In this case, would I present myself as a regular VFR traffic to clearance, ground and tower frequencies and request IFR once at MSA to Center, or would I request an IFR clearance on ground and add the request for VFR climb-out up to the MSA?


texts: Constant TAS versus constant GS: What is the influence on turning circle?

texts:
Scenario

Lets imagine a 50kts wind from east.
Now lets imagine an aircraft flying at 200kts (True Air Speed) east that make a 1.15G turn -90º to north. Maintaining in all moments the given constant speed.

Now, lets imagine the same flight but with 200kts constant ground speed.

In the first case, the speed is 200kts TAS= 150kts GS, and after the turn TAS=GS=200kts
In the second case, the speed is 200kts GS = 250kts TAS, and after the turn, TAS=GS=200kts

Any mistake until now?

The question:
The question is how that influence the turning circle? In which of the two cases the turning circle is flatten/stretched and in which is circular if any? What is the approximate shape of them?

Further explanation

Considering my very weak understanding, the turning circle G depend on absolute speed (~ Ground speed), and thus, turning with a constant ground speed imply a circular turning. Which is independent of the wind. Of course, the pilot would have to accelerate/decelerate to maintain this speed.
With TAS, the real speed is variable, so in our case, I expect to see a turning circle which is horizontally flatten.

But, using a planning system, the result I observe is the reverse: the circle is constant (independent of wind, circular) on TAS and variable (dependent on wind, shape is not drawn) in GS.

Edited: TAS=GS=200kts: I just realized that it is not really true, cause the aircraft need to head slightly east to compensate the wind, so probably the TAS will be ~206 and GS 200. Even if that do not make a big difference for the question.


texts: Do most airport use one and only one runway for landing?

texts: Do most airports (especially busy ones) use only one runway at a time for landing? For example, I know Heathrow uses only one of its runways at a time (although they might switch to another half way through the day).


texts:
With me becoming an aviation enthusiast and AirBerlin becoming insolvent, my mom has gone on a hunt for deals on what I can best describe as AirBerlin merch (old uniforms, shirts, skirts, belts and many more).

In one of the packets that arrived recently she found items that neither her nor I knew the purpose of.

They are about 2cm * 2cm, yellow, have some kind of number on them and on most of them was the writing "Air-Berlin SEALED" or "airberlin group SEALED" and an engraved "PULL". It also looks like you can break off and bend a part in the plastic to the back and clip it there.

Below is a picture I took of a few of these:


texts: What creates most drag during flight: fuselage or wings?

texts:
From pic 1, I know the drag line is below the thrust line, but I am puzzled about where the drag line is in pic 2?

Secondly, what creates most of the drag in flight, is it the fuselage or the wings?


texts: Did any aircraft ever use stick twist for rudder control?

texts: Did any aircraft ever use stick twist for rudder control like some joysticks for video game flight simulators?


texts:
I'm trying to understand the outputs given by the DATCOM method. For example I have this formula for pitching moment coefficient :

DATCOM give me these coefficients related to the pitching moment :
cm, cma, cmq, cmad, and dcm_sym for the elevator contribution.
I have seen in some models that the total contribution would be an addition of static contribution (cm), dynamic contribution (cmq * q * Lref / V + cmad * alphadot * Lref / V), and elevator contribution (dcm_sym).
Is cma "contained" in cm coefficient?
Why is dcm_sym not multiplied by the elevator deflection δm ?


texts: What are the technical details of how airline seats are installed on an airliner? The step by step.  Not made how they are installed.


texts: Is the Boeing 737 unusually susceptible to stress fatigue?

texts:
According to this Newsweek article - which seems like a reputable source - the FAA has issued a number of Airworthiness Directives to address stress fatigue concerns with the 737NG series:

  Between 2000 and 2011, as the number of NG series in the air grew to
  more than 2,000, I identified 13 directives that specifically
  concerned cracking and fatigue issues in the model’s fuselage.

The article focuses on potential issues with the aft pressure bulkhead:

  But the most alarming alert concerned involved a repeatedly troubled
  area called the aft pressure bulkhead (the rear portion of the cabin).
  In an Airworthiness Directive dated Nov. 5, 2001, the agency called
  for “immediate corrective action” to deal with a flaw in the aft
  pressure bulkhead [...] Four airlines had discovered, during
  checks, that if a 737 made a hard landing, damaging the main landing
  gear, or simply a certain kind of hard landing that led to shimmying,
  involving violent swerves on the runway (not uncommon in turbulent
  weather), the forces transmitted from that impact would end up
  damaging the aft pressure bulkhead, fatally jeopardizing the tailfin.

  There were five alerts about problems with this bulkhead. [Prof. Tony]
  Ingraffea, after looking at the [details], told me in an
  email: “Skin cracking and aft bulkhead problems are clearly chronic.”
  [...]
  In a written memo to Newsweek,
  Boeing claimed that to say that there were “persistent problems” with
  the bulkhead is “not correct” but did not elaborate.

Based on the number of ADs (and any other relevant information), is Newsweek accurate in claiming that the 737 is more susceptible to stress fatigue than other, similar aircraft? Is the number of ADs for this issue unusual? Is there any measurably higher risk associated with flying in a 737 because of this issue?


texts:
First, I was unsure where to ask, here on on Physics SE. Second, I have a strong feeling it might have been asked already somewhere but I didn't find it - so if it was, please link as a duplicate.

Classic "plane on a treadmill"

Suppose we have an aircraft standing on a runway and it turns on engines in an attempt to take off. But that's a special runway - it acts like a treadmill moving backwards at the same speed as the aircraft is going forward (dynamically adjusting that speed if necessary).

What I did is I looked through the web on a classic "plane on a treadmill" problem. One of the best hit is xkcd which kind of states .. "yes" and then goes into different options explaining that "there is no plausible way we could build the treadmill matching its speed to the aircraft" (or did I get it wrong?)

Let's suppose we could

That is - regardless of whether it's possible or not to build such a runway, for the purpose of theoretical exercise let's just take is as granted - we have such a runway.

Will the plane still take off? What will happen?


texts: What's the difference between flight level and pressure altitude?

texts:
When should we say flight level and when should we say pressure altitude?

I know they both set QNE 1013.25, but there is a difference between them.

Anyone know?


texts: What does the condition lever in turboprops control?

texts:
Turbojet and turbofan engines have just one control lever that controls the thrust by setting the amount of fuel injected.

But most turboprop aircraft have three levers. One adjusts the fuel flow, one adjusts the propeller speed, but what does the third one do? Does it only act as an on-off switch as simulators tend to present it?


texts: What types of air traffic controllers are there?

texts:
I've heard of many different types of controllers, but I'm not sure exactly what their responsibilities and interactions are.

Here are some examples:

En route controllers
Approach controllers
Ground controllers

What types of controllers exist and what aspects of a flight is each one responsible for?


texts: What is the difference between Part 135 and Part 129?

texts:
I work with small commercial aircraft. Up until now I have understood Part 91 to mean that the flight has been filed as private and Part 135 to mean that the flight has been filed as commercial, to put it simply.

Recently, after a problem I can't go into, my colleague suggested that the problem could have been caused if the carrier was not "Part 129 approved".

What is the difference between Part 129 and Part 135?
Are there any cases in which you would need one and not the other, or both, or neither?
Are there any other "Parts" that can affect a foreign carrier flying to/from/within the US?


texts: Do ultralights need to have EPA-compliant engines in the USA and Canada?

texts:
Do ultralights need to have EPA-compliant engines in:

The USA?
Canada?

Just wondering if you could use a hobby type 2 stroke engine for a twin engine Lazair type ultralight.  I don't think they are EPA compliant.

I know some people use them.  Just wondering if it's actually legal?


texts: What contra-rotating propellers would be appropriate for this engine?

texts:
I am currently getting an X4 cylinder, 150cc, 4 stroke engine 3D CAD Modelled, this engine is initially being designed for Powered Paragliding (PPG), classified as experimental Aircraft, so no certification is required!

I have read several discussions here, that largely relate to large ridged winged Aeroplanes travelling at high ground speed.

PPG is a Low & Slow (22~75kph) Aviation sport, there are obvious differences with this project being;

Most PPG engines max. rev are from 7'000~12'000rpm.
Then a Re-drive is used to slow Prop down to approx. .88~.90 mach.

With a PPG, it is the Wing that sets the Speed in flight, not the engine!
A larger more powerful engine only provides a higher climb rate or maintain lever flight easier.

Most engines of similar capacity swing a 125cm (49/28") Prop at around 2'700rpm to under 3'000rpm.

The engine we are designing uses a unique engine that has replaced the 100yr old conventional crankshaft with a patented Contra-rotating Trilobe centre drive shaft (CDS) technology, that uses two trilobe cams, that strokes each Piston 6 times on One revolution, thus providing 3 combustions in two revolutions of CDS, this engine will not be revving over 3'500rpm maximum.

Engine is currently 12.5kg and 41cm width x 37cm high x 20cm deep.

I am planing on using Two 100cm (40") Contra-Rotating propellers!

I would appreciate it if anyone could assist/help me if this is an appropriate Sized Prop & what Pitch would be best ?


texts: How can best glide speed be lower than best rate of climb speed?

texts:
I was looking up V-speeds for C172. I don't have easy access to an official copy of the POH, but online I found:

$V_y$, best rate of climb speed (at sea level): 76 KIAS (p22)
$V_{glide}$, maximum glide speed: 65 kts (p15).

But I always thought that $V_y$ is the speed for highest L/D, which should give both highest rate of climb and lowest rate of descent, and that longest glide is achieved by flying slightly faster than that, because drag grows with square of speed, and therefore it initially grows slower than speed above the minimum drag point.

So why is the $V_{glide}$ quoted lower than $V_y$?


texts: What does it mean for a wing's lift distribution to be elliptical when the planform is not?

texts: How would you go about finding an equation for the lift coefficient of this wing where the lift distribution is known to be elliptical but the planform is not?


texts: Are there any airliners capable of vertical climb with engine thrust only by pointing the nose up?

texts:
So, sort of inspired by this question, I was wondering if there were any passenger airliners with enough thrust to fly straight up, supported purely through the thrust of their engines rather than the aerodynamic lift generated by their wings - so that once it's flying along, it can just point its nose at the sky and go straight up; if you think about the launch of the Space Shuttle, you’ve got the right general idea. According to some of my comments, this is apparently called a "zoom climb". Note that I'm not asking about VTOL, since some aircraft that are capable of this may not be capable of VTOL due to a lack of thrust vectoring.

I know that some military fighter aircraft are capable of this, but based on some research with Wikipedia, it appears that the Boeing 747, Boeing 787, and the Airbus A380 can't - though the 787 would almost be able to do it if it had four engines rather than two.

Are there any passenger aircraft that are capable of doing this? Obviously they wouldn't do so while passengers were on board, but I'm just interested in the ratio between Operating Empty Weight and Maximum Thrust.


texts: What factors are considered when a runway is planned?

texts: What environmental factors are considered when a new runway construction is planned (e.g. winds, weather, sun direction, etc.)?


texts: Why do some military aircraft use variable-sweep wings?

texts:
There are a couple of American military aircraft (the retired F-14 and the B-1 come to mind immediately), that have variable swept wings.  I know that they keep the wings full out (roughly perpendicular to the body) during take off and landing, and they have the wings swept back for high speed flight.

But I've never really understood why? I assume that at lower speeds the wings-out configuration creates more lift.  But, why does sweeping the wings back help at high speed?

For bonus points: how does the performance gain make up for the cost in weight and complexity created by having a variable swept wing?  Or perhaps there isn't much of a gain and that's why most military aircraft don't have variable sweep?


texts: Is there any regulation that force(or recommend) to change flight number in case of flight delay?

texts:
I have a question about a flight number of delayed flight.
I think that if the daily flight(e.g. OZ9609) is delayed until the following day, there are two flights with a same flight number.
In this case, I think operating two flights with same flight number could cause confusion to passengers and systems related with operating the airport.
So I want to know there is any regulation that force to change a flight number if situation like this case occurs.


texts: I don't mean wave drag here. What is compressibility drag, which is understood to be a form of miscellaneous drag?


texts: Which direction of a forward slip is safer during a turn to final?

texts:
Suppose I'm making a turn from a left base to final and, realizing I need to kill quite a bit of excess altitude, decide to use a forward slip with full rudder deflection (along with full flaps).

Which direction of rudder deflection would be preferable?

I suppose that yawing left would result in less bank and therefore a lower load factor, which may be safe at low speed and low altitude. But yawing right, will result in a steeper bank which (under the same IAS) will result in an even higher rate of descent thereby getting me to the ideal glide slope earlier and leaving more time to fully stabilize before the threshold.


texts: So I was wondering what is the Aircraft categories all about because from my previous questions answer I got to know about something called Cat D type aircraft so it made me curious to know what are the different types of aircraft categories and which one is the A321-271NX because it happens to be special for me !


texts:
I would really like some help on making the decision as to which license is more suitable for my situation. From reading various forums online, others have had the same questions, but I couldn't find a concrete answer anywhere.

My situation:

No previous flying experience
Would like a license so that I can privately rent on a very recreational basis (I expect to average an hour or two per month after obtaining either license, largely due to cost - the local airport will hire out a 172 for £140 per tacto hour (including fuel and VAT), which equates to around £120 per flying hour for typical usage). Taking friends along for the ride would of course, be ideal.
Desire to keep cost to a minimum - I would like to keep the cost of the training, from zero to license to under 8k (pounds/euros) if possible. This includes training materials, lessons, test/exam fees and landing fees. I believe this is possible, if I manage to stick to the lower end of the average number of hours.
Local school offers full LAPL course (providing the minimum 30 hours) for £5290.
Local school offers full PPL course (providing the minimum 45 hours) for £7450.
Both prices are based on learning in a Cessna 150.
The weather in Uk and part of France I move to is not always great. There is often a lot of cloud, rain and wind.

So based on all of the above, which license would you recommend? The LAPL is cheaper, requires less hours (local school says 30) and is more attainable. It can also be upgraded to a PPL at a later date for instrument / night rating. However, due to the weather, will I get to fly as much with the tighter restrictions, if not, maybe it's better to just fork out the extra time and money and go straight for the PPL?

Apologies for the long winded question, I wanted to provide as much info as possible so that I can get the best answer possible as I am very conflicted at the moment but want to make a start. I hope that the answer isn't 'neither'. Which is what I'm worries about, since I don't want to be spending all of my disposable income on flying, I can't very well go out every week.

Location information: The training will take place in the UK, although I will be moving to France shortly after obtaining either license.


texts: Why are commercial aircraft windows typically oval instead of circular?

texts:
Pretty much what the title says. Surely a circular window would allow more window area while not compromising on strength?
Some planes(Gulfstream jets) do have circular windows. Is there a reason for this? does it have something to do with fitting windows without in between structural components?


texts: Was the "Air Berlin" lap of honor over Düsseldorf problematic?

texts:
A few days ago, flight AB 7001 (Air Berlin, New York - Düsseldorf) went for a "lap of honor" around the airport.
One video can be found here.
No emergency or technical issue, it just was that airlines last ever flight on that route (they're bankrupt), and the pilot wanted to give a nice gooodbye.

Now, of course comment-sections on news regarding this are full of "experts" saying if it was ok or not. Here the question for the ACTUAL experts I can reach:
Did the pilot do anything "bad" or even dangerous, or should a quick circling of the airport be just fine as long as the pilot can actually, well, fly his airplane properly?

UPDATE:
The Bundesaufsichtsamt für Flugsicherung (BAF) (German bureau for flight-safety) agrees with this page, the manoeuvre was ruled to have been legal and safe.


texts: Where can I ask questions (career advice) about jobs in Aviation Management?

texts: I am thinking of changing my career. I have a physics degree and I want to do a masters in aviation management.Is there any sites where can I get an idea about my chances at getting a job in the aviation management sector, if I do a masters? (with no prior experience).


texts: What aircraft had the first pilot-assisted controls?

texts:
This question about regulations regarding hydraulic flight controls got me thinking about the history of hydraulic or pilot-assisted controls. As aircraft get larger the control surfaces must grow proportionally but it seems that the forces required to move those surfaces may grow at a non-proportional rate. That means at some point they had to switch from a pure cable/pulley system to an assisted system.

What is the first aircraft to use an electrical/mechanical/hydraulic system to assist the pilot with the control surfaces? I'm mostly interested in an answer from a commercial aircraft standpoint.


texts: How does the aviation industry train and certify English proficiency?

texts:
How does the aviation industry (pilots and ATC in particular, as opposed to cabin crew) train and certify English proficiency? Do they use classes and examinations associated with general-purpose English training, or ones specifically associated with the aviation industry?

I heard several years ago from Air Crash Investigation that a contributing factor for the Avianca Flight 52 crash was the use of the wrong terminology in communication between the non-native speaking pilots and the ATC.


texts: Why are the MSA direction needles not oriented to north?

texts: Why is it when you look at an MSA the arrows are pointed opposite of where they should be?


texts:
Does anyone have an idea of what is it? From what I gathered from the web, it seems that this is the margin of error between the actual, real fuel consumption of the aircraft and the fuel consumption recorded in the aircraft systems (FMC?). I read that the system only estimates the fuel consumption via the fuel flow, which has some degree of inaccuracy.

Airbus and Boeing seemed to have different terms for this, PERF Factor, Fuel factor. The seem to be close in definition but I'm not really sure.


texts: How can I get back up into flying after not flying for over 20 years?

texts: I'm a former USAF pilot and former Bonanza owner. Haven't flown private in more than 20 years, but looking to get back into it. A friend who owns a 182 and will fly with me and I know some instructors. I don't even know where my old certificate and log book is, so this is really starting from scratch. What steps do you recommend?


texts: How to properly implement and understand Theodorsen's function?

texts:
I'm attempting to implement Theodorsen's lift deficiency function for an airfoil experiencing a harmonic variation in angle of attack due to an oscillating freestream (i.e., not pitch oscillations).  Following Leishman's Helicopter Aerodynamics I have an expression for this (as follows), but I'm unsure how to implement it.

$C_l=2\pi\left[C(k)+i\frac{\omega b}{2v_\infty}\right]\bar{\alpha}e^{i\omega t}$

where $\omega$ is the circular frequency of the AoA oscillation, $\bar{\alpha}$ is the amplitude of the oscillation, $b$ is the semi-chord length, and $C(k)$ is Theodorsen's function, evaluated at a given reduced frequency.  I get my values for this from http://soliton.ae.gatech.edu/labs/windtunl/classes/unstaero/unstaf/theofn.html.  This expression is then plotted against angle of attack, given as $\alpha=\bar{\alpha}sin(\omega t)$.  Using Matlab to plot the real part of this expression, I get the following:

As shown, all I get is a rough circle.  I should be able to plot a hysteresis loop similar to this (from Leishman, Principles of Helicopter Aerodynamics, 2006):

I realize that both plots are for different ranges of angle of attack, but the expression should produce similar results (in terms of trends, appearance) in either case.  Am I missing something on the implementation of this function, or in my understanding of what this function should do?


texts: Why do commercial airplanes smell like fuel smoke before take off?

texts:
Why does the cabin of commercial airplanes always smell like fuel smoke coming out from the internal ventilation a few minutes before taking off, I think when the pilot puts thrust into the engines before going to the runway?

A few days ago I went on a trip and noticed this too, when landing. Is it normal?

What is the reason to have the passengers smoked?

Thanks!!


texts: What factors determine the direction of the resultant force vector?

texts:
The overall aerodynamic force acting on a wing that is creating lift is not straight upward but is inclined backward. We usually consider the vertical and horizontal axes of the force separately. Lift is defined as the portion of the resultant force that is perpendicular to the relative wind, and induced drag is the portion parallel with it. The slope of the angle of the resultant force is the L/D ratio. This ratio changes with angle of attack as shown in the following diagram. As the AoA increases this vector leans further back creating a different L/D ratio (more drag for the same amount of lift).

Then looking from the wing's point of view, the portion of the RF perpendicular to the chord is the normal force (N) and the part parallel to it is the axial force (A). We can see that the the angle of the RF with respect to the wing chord is less affected by changes in AoA.

I've never seen a chart that graphs out the N/A relationship. Does this ratio change at all with AoA or is it a fixed property of the wing design? If it is not fixed, what dynamic factors (speed, AoA, etc.) affect the direction of the resultant force?


texts: Can one make an electric-sailplane from transparent carbon fiber?

texts:
Is it technically feasible to make a sailplane from transparent carbon fiber? I am looking for an answer based on the specifications' comparison of the 2 different fibers.

And can it be made self-launch capable with an electric motor ? ie. the difference in the design considerations while positioning and designing an electric motor for a normal glider vs a carbon fiber glider; Eg. Sparrowhawk.


texts: To what extent does pressurisation increase the rigidity of an airframe?

texts:
A vessel such as a balloon or the rubber air-cell of an inflatable boat will become more rigid when pressurised.

The same must happen to the fuselage of a pressurised aircraft - but to what extent?

Unlike balloons and inflatable boats, aircraft are not flaccid when unpressurised...

I imagine that the effect must be so tiny as to be not just utterly negligible, but literally impossible to measure; is it possible however to calculate theoretically (and if so, of what order is it likely to be)?


texts: What happens if you exceed the maximum speed on a C172?

texts: The airspeed indicator has a red marking that means: "never exceed this speed" ($V_{NE}$, around 160 KIAS). Why can't you exceed that speed?


texts:
Given the:

True Heading = 070 degrees

True Track   = 061 degrees

True Air Speed = 120 knots

Ground Speed = 118 knots

what is the wind variation?

these are the steps I am taking to calculate the wind variation:

1 - put the true heading on top - the true heading is 070 degrees

2 - put the true air speed inside the little circle - the true air speed is 120 knots

3 - mark the drift ( true heading - true track) = (070 - 061) = 9 degrees on that line

4 - draw down to the ground speed (118 knots)

5 - bring the little blue circle back to zero

6 - rotate the disk so that the cross is on the central line

there I can see that the wind comes from 151 degrees at 19 knots.

Questions:

will this always be correct?

Could I have calculated it through a formula (without using the computer)?


texts: Why do turbofans have different nozzles?

texts: The CFM 56-7BE (on the 737) has a long and narrow nozzle, the RR Trent 900 (on the A380) has a sharper nozzle, and the CF-6 (on the 767) has a wider opening at the nozzle. Why do the nozzle sizes vary among turbofans?


texts: What does the ‡ symbol in the Chart Supplement (A/FD) designate?

texts:
In the Chart Supplement there is occasionally a ‡ symbol after the operating hours for control towers (and other time information) like what's shown below.

What does the ‡ symbol represent?


texts: Does the ARCA hoverboard violate known limits on small-diameter electric fans?

texts:
The ARCA board is being hawked as achieving 430 pounds of lift from 36 electric fan motors for six minutes of 'flight.'

c.f. : http://www.theverge.com/2015/12/24/10663228/arcaspace-arcaboard-hoverboard-skateboard

To my uneducated eye, getting 12 pounds of static thrust from each of the small fan motors (430 pounds / 36 motors) seems unreasonable and perhaps impossible. The engineer says that it has 272 horsepower, so that would be 7.56 horsepower or 5.6kW per motor, which seems on the high side.

What are the a) theoretical and b) realistic amounts of thrust that one can assume from what looks like a 10-15cm diameter fan?


texts:
In addition to my previous question, I am mainly concerned with burning all the fuel.

Why isn't the combustion process using all of the Oxygen in the air?
Is it because other gases are in the way and it isn't in the right place to help the reaction?
Are engineers limiting the amount of fuel into the process because they know some of the Oxygen won't be available for combustion due to its proximity(lack thereof) to the fuel?
How much fuel remains un-burnt in a modern jet engine?
I thought that an after-burner was meant to use the fuel that somehow got through the whole process without combusting?
Wouldn't using pure O2 allow for a complete fuel burn?
I do get that the added weight may not make it worthwhile since we need to weigh the value of complete burn against other non-monetary concerns(like pollution).

Finally, I assume the 2000-2500 degree C temp mentioned (in this answer) in the last post is to actually burn Oxygen. Although I know Oxygen is not flammable, I am sure everything does burn at some point. I do not want to actually burn the Oxygen.


texts: Does an airfoil in supersonic flow have zero circulation?

texts: In incompressible flow, the Kutta-Joukowski theorem can be used to relate the lift (per unit span) to the circulation around an airfoil. However, if we look at an airfoil or the flat plate (see below) in supersonic flow with shocks, how can we show that there is circulation? And, if there is circulation, then how do we calculate it?


texts: How long does it take for a new FIR to be created by ICAO

texts:
How long does it take ICAO to create/approve a new Flight Information Region(FIR)?

Occasionally FIRs are split because of various reasons. The question is how long ICAO takes to approve the new FIRs creation.


texts: What aircraft did this canopy come from?

texts:
This canopy was found near Wetumka, Oklahoma in a small creek running through my best friend's property. The canopy is about 12 feet long. Can anyone tell me what aircraft it came from, or who I could contact to ask?

A loving cup from 1906 dedicated to a Miss Grace Walling Spore from the USS Alliance Navy Ship was also found in same creek recently. I contacted the family myself and they knew nothing about the loving cup or any crashed plane that may have been carrying it.

Here is another picture... I do not know if was in a crash.

It could have washed down creek I suppose, but why would a jet canopy have been in a creek? I am searching for what kind of craft it belongs to.

Location: A creek in Wetumka, Oklahoma
Rumored date/pilot: 1944 / Loyde Christian
Object length: ~12 ft


texts: For airplane spotting, what minimum specs should a telescope have?

texts:
We are thinking about buying a telescope for viewing planets, stars, the moon, and aircraft! What is the absolute minimum zoom and/or size to achieve getting a good glimpse of an aircraft at its cruising altitude?

Does anyone have experience doing this that they could share to help us out?


texts: Under what circumstances can the Initial Climb Area extend more than 2 nautical miles?

texts:
While studying of FAA's Instrument Procedures Handbook, I noticed that on page 1-16 (Chapter 1: Departure Procedures) it defines the Initial Climb Area (ICA) as follows:

  The ICA is the segment of the departure procedure that starts at the DER and proceeds along the runway centerline extended to allow the aircraft sufficient distance to reach an altitude of 400 feet above DER elevation and to allow the establishment of positive course guidance by all navigation systems. A typical straight departure ICA extends 2-5 NM from the DER along the runway centerline extended. It is 500 feet wide each side of the runway centerline at DER, then spreads out at 15°

However, I can not understand how it is possible for the ICA to extend more than 2 nautical miles, since the maximum horizontal distance covered by an aircraft until it reaches an altitude of 400 feet above DER elevation can be found by using the default minimum climb gradient of 200 feet/NM, which corresponds to 2 nautical miles. For an ICA to extend more than 2 nautical miles, a climb gradient of less than 200 feet/NM would be required, something that violates the rules imposed by FAA.

Could someone point me in the right direction?


texts: Why was the 747SP not very successful with sales and longevity in service with the airlines that did purchase it?


texts: What is the relation between aircraft stability and control?

texts:
:)
My teacher gave the task to figure out the common relation between stability and control. I know definitions and only thing I could find on the internet was "Control is directly opposed to stability" but I am not sure if I get it. Thank you for your answers :)


texts: On commercial jets, is asymmetric thrust used as part of normal operations?

texts:
I know that when manoeuvring on the ground, asymmetric thrust is often used, for example to assist in turns when taxiing.

Are there other circumstances in normal operations which might call for the use of deliberate asymmetric thrust in manoeuvring?

I am specifically not asking about emergency or other abnormal ops, flight testing or auto-throttle operation.  I could rephrase the question as "in day-to-day ops of flying an multi-engine commercial jet, is asymmetric thrust ever used to manoeuvre the aircraft when not on the ground?".


texts: When does the 18-month time limit begin for the JAR ATPL examination?

texts:
Here is an extract from JAR-FCL 1 concerning the period during which it is necessary to pass 14 ATPL exams:

  Subject to any other conditions in JARs, an applicant will be deemed
  to have successfully completed the required theoretical knowledge
  examination for the appropriate pilot licence or rating when awarded a
  pass in all of the required subjects within a period of 18 months
  counted from the end of the calendar month when the applicant first
  attempted an examination.

So taking this into account, it is possible to have 19 months to pass all the remaining ones (13, in case of a success during the first sitting) after first exam sitting in reality if you sit it on the first day of the month. For example, if you take first exam on the first of March, during the remaining part of this month the clock isn't ticking and will start doing so only on the first of April, so you get an additional month. Am I right?


texts: Why safe take off weight exceeds the safe landing weight?

texts: This looks contra-intuitive: if a plane can take off and fly horizontally, what prevents it from descending and touching down to the runway with the required small vertical speed?


texts: Why isn't the arresting hook always used on land?

texts:
Watching Jet Stream, about training to fly the CF-18 Hornet, they comment that the jet was originally certified as a Navy plane, landing on aircraft carriers with an arresting cable.

Usually, when landing on land, they land hard and fast and take a mile of runway to come to a stop; but during an emergency, they use the tailhook which brings the jet to a stop after only 1,000ft.

My question is: why don't they always use this to land?

Here's a short clip I've taken from the show:


texts: Does wearing glasses mean you automatically meet the first class medical requirements?

texts: I have been wearing glasses for a very long time. If you wear permanent eyeglasses do you automatically meet the FAA first class medical vision requirements?


texts: Why are there no commercial supersonic flights at present?

texts:
I'd think that on certain heavily trafficked routes, especially ones with lots of business travelers, there would be a market for high-speed (supersonic) flights?

Why are there currently no supersonic commercial flights? (Or are there?)


texts: Why don't commercial aircraft use all-movable tail surfaces like my RC plane?

texts:
Many conventional RC planes use control surfaces at the tail just like the image below:

You can see there is a part in front of each surface control that never moves and only the surface control itself moves.

So, I built an rc plane without that part in front of the surface control. Take a look below:

This plane I built flies really well (no aileron). So I was wondering: why commercial aircrafts or even rc planes dont use this type of rudder/elevator without the part in front of it? See: making the control surface the way I did reduces drag since you dont have a fix part at the tail that does nothing, it reduces weight cause you just need the control surface and nothing more and it is also way easier to build. I cant understand why commercial aircrafts and rc planes dont make use of this exactly same type of rudder/elevator!

Could you please tell me the reason?


texts: What is the maximal delay between the publication of an investigation report recomending a study and the beginning of this study?

texts:
This question is focused on EASA regulations, mainly because the question arise when reading an investigation report written by the BEA.

Investigation reports results in lots of recommendations to improve safety. Some recommendations involve certification process and are then implemented when certifying new aircraft types, other involve training process and are then implemented by modifying training, other recommend studies.
For example, if I take the AF447 final report, the section 4.3.7 recommends that:

  EASA study the relevance of having a dedicated warning [...]

This is not the only study recommended by this report, this is just an example.
On another report named Study on aeroplane state awareness during go-around (2013) (which proves by its title that studies are conducted), the section 8.2 recommends that:

  Manufacturers study the feasibility of simplifying the management of the aircraft reconfiguration [...]

Then I imagined this lead to other studies.

In short, reports by investigation entities (NTSB, BEA,...) may recommend studies to be conducted. This leads to other reports, possibly asking for other studies to be conducted. It looks like an endless, yet useful, process.

Are those recommended studies always conducted (maybe this is ensured by an EASA regulation I'm not aware of)? If so, is there a maximal delay after the publication of the recommendation to start the study? Are studies recommended by different types of publication (accident reports, studies report,...) treated differently in respect to those delays?


texts: What software generated this VFR flight plan?

texts: I recently came across this screenshot of a VFR flight plan.  Does anyone know what software was used to generate it?


texts: In the 1980 comedy movie Airplane!  Are there some jokes that only pilots would get?  I always thought there was sight gag with the runway when they are taking off.  The runway look likes it has exit ramp like an interstate highway.


texts: Carburetor Heat Required on Carburetor equipped GA aircraft?

texts:
Is Carburetor Heat Required (by FAA Certification regulations) on Carburetor equipped GA aircraft?
If not, what (if any) certified carburetor-equipped GA aircraft do NOT have Carburetor Heat installed ?


texts: What is the largest plane ever to have been stolen by a single pilot?

texts:
This guy stole a few small planes like two c172s, a 182 and a Columbia 400.

Also, in 2003 two persons stole a Boeing 727.
Has there been other cases like this one where someone stole a large aircraft? If so, what is the largest aircraft to ever been stolen, preferably by a single person?

(To clarify, I'm doing some research for a story I'm writing. I don't plan to beat the record, rest assured.)


texts: Which flap is better suited? Split or Plain?

texts: I’m considering which flap to build onto a home built aircraft, but not exactly sure which flap would best fit the aircraft and which one would be more beneficial. The aircraft has a fighterlike look to it, but I’m mostly worried about how the flaps will effect airflow during landing and takeoff.


texts: How does a constant pressure chart affect your preflight planning?

texts: Would you choose a route or altitude based on the information in a constant pressure chart? How does a constant pressure chart help a pilot plan his or her flight?


texts: Compressor-Turbine: Why a shaft and not kind of a "rotating drum"?

texts:
I'm studying the fundamentals of jet propulsion and its applications. I really have this next question and haven't found an answer yet: why do jets use a shaft (or more) to connect the turbine(s) to the compressor device(s), but not a "rotating drum" instead?

What I call a "rotating drum" (I sketched it below) is a thin, rotating cylinder that has built-in rotor blades at the beginning and exit.

I'd like to know if this is a feasible arrangement, and what would be the disadvantages of it. I think this might be unfeasible because:

There would be a lot of thermal stress at the middle of the drum.

But if we were to overcome this drawback somehow, I think we would benefit in the following ways:

Less weight, I think, with respect the traditional shaft system.
More internal space (no hollow) for other demanding components, like the combustor. The combustor could be made a bit larger, thus increasing the burning efficiency (more reaction time for reactants, ...).

I don't know how correct/wrong I am. This is a question out of pure curiosity and I wanted to get some feedback on it. Should I go ahead and start working on a small scale prototype of it? Hope my question here is not too basic.

PS: The sketch I made is just that: a sketch. Therefore, important things like the relative number of stages compressor-turbine, or the increasing/decreasing areas for each of those two components, do not appear.


texts: What happens when a GA pilot squawks 7500?

texts: If you were to put code 7500 into your transponder in a small general aviation aircraft, and you were in a rural area with no one around, and you did not have enough fuel to get to any city, what happens? Would they shoot you down? {edit what I meant was if you were being Hijacked and you on purpose sqacked 7500


texts: Could TCAS be overwhelmed by multiple conflicting traffic and "give up"?

texts:
I understand that TCAS can handle several "targets" simultaneously. However, I'm interested in the (highly hypothetical) scenario where TCAS would need to deal with multiple conflicts in a dense environment.

Is there a point where TCAS goes into some sort of "cannot resolve" mode becoming effectively inoperable, or does it try to cope with everything thrown at it, even if it leads to impossible solutions (defined here as maneuvers outside the flight envelope or the ability of crews to follow in a timely manner)?


texts:
How are anti-aircraft missiles and counter-measures tested?

When they design an anti-aircraft missile, how do they test it so that it actually locks on to a target and destroys it? Do they simply fly a plane in the air and then fire a missile at it and have the pilot eject?

Similarily, how are counter-measures tested? Do they fire a missile at a target and check whether it misses?


texts: Is a single-engine ferry flight allowed with a twin-engine plane?

texts: If a twin-engine aircraft has an engine problem and could fly somewhere for maintenance, is a single-engine ferry flight ever allowed? If so, do airlines or pilots ever decide to do this?


texts: Why does the A320 right aileron float on dual engine failure?

texts:
On this question for the A320 after dual engine failure it says:

  When the hydraulic power is lost, the right aileron is lost, and is in the upfloat position.

Why would this affect only the right aileron?


texts: Can some or all helicopters have contrails? If only some, why only those? If not, why can they not? Pictures would be really helpful. I do know that turboprops and piston props can leave contrails, but I haven't been able to find anything about contrails on helicopters.


texts: What is the lifespan of commercial airframes (in general)?

texts: You always hear that the Boeing 737 have been flying for so many years and the Airbus A310 for that many years, but of course that include new airframes being produced all the time. What is the lifespan of one airframe on average in general use by airlines, before it is scrapped?


texts: The propeller of this light airplane almost looks like a triangle, so I'm interested in knowing its performance but I need help in identifying this plane because I don't even know her name.


texts: Where does the Oxygen for the emergency gas masks come from?

texts: Normal commercial jets drop gas masks when cabin pressure drops, and supply oxygen, but, where does that oxygen come from? Do commercial jets store oxygen? If they do, isn't pressurised oxygen very flammable and too hazardous to carry?


texts: How much thrust is required for a Boeing 747 to "keep flying" at 4 km altitude?

texts: Not full power, just enough to keep the plane moving at 4km altitude.


texts: Does a helicopter's boundary layer have different properties that are caused by the rotation? How does this affect stability of the helicopter?

texts: I recently got introduced to the boundary layer theory of an airfoil, and I couldn't stop thinking of how it would be affected by rotation as well as the varying speeds of rotation.


texts: Is having the tailplane at the wings backwash a design flaw?

texts: Most airliners have their tailplane below or above the backwash of the wings, so is placing the tail control surfaces directly in the backwash  of the wing a disadvantage?


texts: Can spar stresses be calculated using zero (wing) fuel?

texts:
For a homebuilt prototype aircraft meant for the primary or Canadian JAR-VLA category, is it OK to assume that spar stresses (other than landing loads) can be calculated using zero-wing-fuel numbers? Or perhaps the landing loads usually negate that zero-fuel stress relief?

So, when specifying plus and minus stresses, both the wing and its fuel content can be discounted except for full-fuel aileron loads?


texts: What can I do to save my life if oxygen masks fail to drop down? Is it possible?

texts: What is the safest and fastest solution (method) in this situation?


texts: Why don't we see business jets with wingtip fuel tanks anymore?

texts:
There is something I miss from the Learjet 35 (one from FS95/98) that I don't see any more:
Fuel tanks on the wingtips!
What happened to the wingtip integrated fuel tanks in the business jet industry?


texts: What difference does the choice of paved runway surface make to aircraft?

texts:
What difference to the pilot does it make it say a runway is Concrete or Asphalt?
Does it require different information in the flight management system or other calculations?


texts: What physical tests are involved with verifying a wing spar is suitably constructed for a homebuilt aircraft, such as the piper cub kit from wicks?

texts: During construction how is a spar tested to ensure it can adequately cope with bending and twisting forces of the completed structure, or is this performed after complete?


texts: What military aircraft has six propeller engines?

texts: Today, in south-east Scotland, I saw a plane that looked a bit like a Hercules but had four pods on each wing. I'm pretty sure that three of them were propeller engines and the end one was something else. They all looked a similar size. Height was lowish but not very low and it did not show up on flightradar24.  I could not discern colour. I didn't get much of a look as I rushed in to get binoculars and it was well past and banking to the right when I got out again.


texts: Is a Cessna 172S still airworthy if factory-installed instrumentation not required for day VFR flight is inoperative?

texts:
A C172S I occasionally rent had the EGT gauge placarded INOP when it had a JPI EDM-700 engine monitor installed. The placard sits on the gauge so you can no longer see the needle. Probably the single point EGT probe has been removed so the needle wouldn't work anymore. Of course that is fine - the EDM-700 is TSO'd.
Now recently the EDM itself is placarded INOP and its circuit breaker collared so it cannot be reset.

So now this 172S has two INOP EGT gauges, and I'm down to leaning by ear. I know the EGT gauge is not required daytime VFR equipment. However, since the airplane was certificated having a factory EGT gauge installed, I'm wondering whether it's airworthy like this. The Plane is N-registered and I'm asking within FAA jurisdiction.


texts: I know that they repair everything that concerns engines, but what is the actual day for them. Do they sit in the factories or work in airports?


texts: Why are there many different approach lighting systems?

texts:
Why not just have only 2 or 3? What's the point of having such a number of different configurations? What's the practical application of each lighting scheme? I mean, do they really help pilots in a different kind of way?

(source)