Aviation Stack Exchange Community Digest

Top new questions this week:

What is this quad-jet plane at El Paso Airport?

If you look at El Paso International Airport on Google Maps, on the south side apron and across from a hangar that is labeled "Sierra West Airlines" (west of the NASA facilities) there is a small ...

asked by William Taft 36 votes
answered by Zeiss Ikon 62 votes

What does "28 volts DC" mean, really?

The common battery voltage on aircraft is commonly referred to as "28 volts". What does that really mean in terms of a lead-acid battery? In many uses, such as cars ("12V"), trucks ("24V") ...

electrical-system battery  
asked by Harper - Reinstate Monica 34 votes
answered by HiddenWindshield 33 votes

Why is the most common hydraulic fluid so poisonous?

The usual hydraulic fluid, Skydrol, is poisonous. If it makes it to the air conditioning system, it causes fume events that may have adverse health effects up to and including at least one fatality. ...

aircraft-design safety hydraulic-system  
asked by Jan Hudec 28 votes
answered by Koyovis 23 votes

Do turbofan engine cowlings dilate during spool-up?

I was watching this Youtube video, portraying a Fokker 70 taking off. I wouldn't have noticed if it weren't for a comment, but during spool up (~ 3:24 in the video), it appears as if the engine ...

turbofan engine-design  
asked by Digital Dracula 20 votes
answered by Jpe61 45 votes

What determines the direction of rotation for counter-rotating propellers?

As Wikipedia and other sources make clear, most twins with counter-rotating props are configured with the left (#1) prop turning clockwise (as viewed from behind the plane) and the right (#2) prop ...

aerodynamics multi-engine propeller-aircraft  
asked by apDafydd 14 votes
answered by Mike Sowsun 21 votes

What does it mean when autoland is fail passive / fail operational?

The below explanation is what I've got from the internet about fail passive and fail operational: Fail operational - Where you have 3 autopilots engaged, such that any single failure will result ...

landing terminology airbus-a320 autopilot autoland  
asked by Johnson 8 votes
answered by kevin 10 votes

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

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 ...

faa-regulations flight-instruments cessna-172 airworthiness mel  
asked by Philipp 5 votes

Greatest hits from previous weeks:

What are the effects of the Boeing 787's very flexible wings?

I recently came across this picture of the Boeing 787 series aircraft's incredible wingflex: I suppose this is a consequence of using very light CFRP wings, but how does the wingflex itself improve ...

aerodynamics aircraft-performance wing boeing boeing-787  
asked by shortstheory 33 votes
answered by Dan 24 votes

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

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 ...

asked by McGafter 24 votes
answered by DeltaLima 21 votes

If a typical passenger plane had total failure of all engines mid-flight, is it possible for passengers to survive?

I have pretty bad flying phobia and often wonder what would happen if all the engines on the craft went out at the same time. I initially had the anxiety-ridden thought that the hundreds of thousands ...

safety aerodynamics airliner emergency  
asked by Elegant Codeworks 34 votes
answered by shanet 60 votes

Is this plane landing or departing?

I have a picture of Air Force One I took fairly up close several years ago. Unfortunately, I don't remember if that was on arrival or departure. Is there anything visible in the airplane's ...

landing flaps air-force-one configuration  
asked by abelenky 121 votes
answered by J... 95 votes

What is ETOPS and how does it work?

According to this press release by Boeing earlier this year, the 747-8 has received its ETOPS 330 rating. This is required by all 4-engined planes made after February 2015 to fly beyond 180 minutes ...

faa-regulations aircraft-maintenance aircraft-certification boeing-747 etops  
asked by collector 29 votes
answered by kevin 29 votes

Why can't an Airbus A330 dump fuel in an emergency?

It was reported recently that the Swiss flight LX18 from Zurich to New York had detected an engine issue shortly after take-off and decided to land back in Zurich. Apparently, the Airbus A330-343 ...

emergency airbus-a330 fuel-dumping  
asked by Quora Feans 38 votes
answered by John K 42 votes

What are the advantages of a forward-swept wing over a rearward-swept wing?

What are the advantages of a forward-swept wing vs. a rearward swept one? Image credit: NASA Image credit: Paul Maritz / Wikimedia

aircraft-design wing  
asked by flyingfisch 30 votes
answered by SSumner 25 votes

Can you answer these questions?

Did the Wright brothers patent their Wing Warping method in Germany?

I know that the Wright brothers patented their Wing Warping method for controlling the roll of a plane or glider in Great Britain, France, United States, Austria, Italy,... but did they obtain a ...

aviation-history roll  
asked by Simplex11 1 vote

During airshows, how common is it to fly armed with (inert?) missiles?

I notices that these three Su-35s were armed with missiles during an airshow. At the 1-min mark, you can clearly see that jet #38 has 2 missiles under each wing as well as a bomb / (spare fuel tank?) ...

fighter missiles airshow  
asked by user312440 2 votes

Does the 737 MAX's engine nacelle camber affect the pitching moment?

A side view of the B737 MAX's engine nacelle shows a positive camber at the top. As nose camber of any lifting shape (wing or nacelle) generally allows more lift at higher AoA, do you think this ...

boeing-737 stability  
asked by Paul Lucas 2 votes
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