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70 votes
Accepted

Why do private jets such as Gulfstream fly higher than other civilian jets?

There are several reasons and none of them really have to do with a private jet being more aerodynamic than a commercial jet. Private jets have better power to weight ratio than commercial jets so it ...
GeoXXX's user avatar
  • 666
56 votes

What prevents a small plane like a Cessna or Piper from flying as high as a jet?

We will take the case of an unsupercharged piston engine, as used in most small Cessnas and Pipers. All engines need the oxygen in air to burn their fuel. As an airplane climbs, the air thins out and ...
niels nielsen's user avatar
53 votes
Accepted

Do the Mt. Everest rescue helicopters have modified engines to operate at high altitudes?

No, the helicopters are standard production versions. The Eurocopter AS350 is a common model used for these operations. In 2005, Didier Delsalle landed a Eurocopter AS350 B3 on the summit of Mt. ...
fooot's user avatar
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46 votes
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How is altitude reached by aircraft flying above the stratosphere measured?

They used inertial altitude on the X-15 for high altitude measurements. This works just like an IRS (Inertial Reference System), which was used on airliners of that era: you can get the position (...
Bianfable's user avatar
  • 55.9k
42 votes
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Could the SR-71 Blackbird be used for nearspace tourism?

Significant issues with the concept: the SR-71 lacks RCS, so you'd lose attitude control if you got significantly above normal operating height. I originally wrote that it doesn't handle in-flight ...
Zeiss Ikon's user avatar
  • 17.1k
42 votes

Does breathing 100% oxygen cause health issues?

When we discuss a mixture of gasses, it's often useful to compute the pressure of each component separately. This is called the "partial pressure" of that component. For instance, oxygen ...
HiddenWindshield's user avatar
36 votes
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Why are planes required to cruise at round flight levels only above 18000 ft of altitude?

In general, the minimum vertical distance two IFR aircraft can be (if they are not separated laterally) is 1,000 feet. This allows for inaccuracies, for example due to: altimeter error ...
randomhead's user avatar
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30 votes
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Are there any gliders that can fly over the Himalayas?

Do gliders (sailplanes) use ridge and wave lift in the Himalayas to go to extreme altitudes, possibly above Everest's peak? Yes, there are gliders touring Himalayan peaks over 8,000m, including ...
mins's user avatar
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29 votes
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Which aircraft can fly at FL600 or above?

Commercial Airliners: Both Concorde (service ceiling FL600) and the Tupolev Tu-144 (service ceiling FL660) could reach FL600. Most airliners have a service ceiling of around FL410 though. Business ...
27 votes
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What prevents a small plane like a Cessna or Piper from flying as high as a jet?

What limits a small plane to be able to fly at a much higher altitude? Money. Power and lift on an aeroplane both decrease with increasing altitude, as shown in the image above, from my paper copy ...
Koyovis's user avatar
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27 votes
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What does the "High Alt Landing" guarded push button on the A320 exactly do?

The button raises the altitude at which the oxygen masks in the cabin automatically deploy. When landing at a high elevation airport, the masks might otherwise deploy during approach when the cabin ...
Bianfable's user avatar
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26 votes
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Is there anything important to know about flying at ~9000ft for the first time?

There's really not that much difference between flying at 3,500ft and 9,000ft, however yes there are a few things you should be aware of. The most important, as usual when operating an aircraft, is ...
Jamiec's user avatar
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24 votes

How do planes know what altitude they're cruising at?

Above Transition Altitude (e.g. this is 5000ft in Germany) the altitude is measured in flight levels (FL) - each FL equals 100ft and is measured above an artificial QNH of 1013,25 hPa. If you cruise ...
pcfreakxx's user avatar
  • 1,988
23 votes

Could the SR-71 Blackbird be used for nearspace tourism?

I work and have worked with several SR-71 crew members. In the past, they have pointed out two principle impediments: Crew workload Cost Crew workload is shared between both crewmembers, and the ...
mongo's user avatar
  • 17.8k
22 votes

Why do private jets such as Gulfstream fly higher than other civilian jets?

There are three main factors that let corporate jets with 50000+ ceilings get up that high. First and most importantly, they have very large wings. Partly this is because of the need for fuel ...
John K's user avatar
  • 132k
19 votes
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What are the limiting factors for high altitude planes (e.g: U2 or SR71) preventing them from going higher?

The limiting factor for subsonic aircraft, including the U-2, is well explained here. For supersonic aircraft this answer simply says the limit is "a combination of wing loading and maximum speed". ...
Peter Kämpf's user avatar
17 votes

Does breathing 100% oxygen cause health issues?

Yes... but not predictably, and (almost certainly) not seriously. If you're worried for yourself and you're not already dead and not doing any crazy maneuvers, it is vanishingly unlikely that you need ...
fectin's user avatar
  • 474
16 votes

Could the SR-71 Blackbird be used for nearspace tourism?

Typical SR-71 missions proceeded as follows: Fill tanks on ground. Tanks leaking fuel like crazy, by design. Plane takes off, with fuel leaking everywhere. Plane gets to altitude, and flies very fast ...
John's user avatar
  • 269
14 votes
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How are aircraft separated at high altitude?

First of all, there is no such thing as a stall speed, but that is a topic of its own. The ATC system has numerous ways of dealing with keeping aircraft separated, even at high levels. Let me try to ...
60levelchange's user avatar
14 votes
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Is there a limit to the possible altitude for electric jets?

That electric propulsion needs no oxygen is of little help for flying high. The composition of the atmosphere does not change too much with altitude, so it is the low atmospheric density which limits ...
Peter Kämpf's user avatar
14 votes

Why are planes required to cruise at round flight levels only above 18000 ft of altitude?

This answer is specifically for the US-- Above 3000' AGL and below 18000' MSL (which is not the same thing as FL 180)1, cruising VFR traffic flies at MSL altitudes which are "round" numbers ...
quiet flyer's user avatar
  • 22.7k
13 votes

What prevents a small plane like a Cessna or Piper from flying as high as a jet?

The previous answers give an excellent overview of limiting factors regarding high altitude flight with powered civil aviation aircraft like a small Cessna. Of interest might be that people have ...
Thomas Perry's user avatar
  • 1,280
12 votes

Can a light glider without thermal protection land from the orbit, starting from the orbital speed?

No. The stagnation point temperature goes up with the square of true air speed. Temperature dissipation is proportional to true air speed and density. Lift is proportional to the square of airspeed ...
Peter Kämpf's user avatar
12 votes
Accepted

What special tyres (tires) are needed for high altitude takeoff and landing?

The higher takeoff speeds might exceed the speed rating of the usual tires. As a tire is rolling it deforms in two directions. As each section comes in contact with the runway it is pressed inward ...
TomMcW's user avatar
  • 28.6k
11 votes

Is it possible for a modified hang glider to land safely coming from orbit?

That's pretty much how space shuttles and other orbiting craft work. They are dropped from orbit, they do calculations to enter the atmosphere at a velocity and attitude that doesn't burn up the ...
Burhan Khalid's user avatar
11 votes

Does high density altitude affect your landing speed?

Your $v_\mathrm{ref}$ does not depend on density altitude since it is given in Indicated Airspeed, which already accounts for density effects. However, the True Airspeed and therefore also Groundspeed ...
Bianfable's user avatar
  • 55.9k
10 votes

What forces act on an airplane's door from the outside in cruise?

A door that is, say, 36" x 80" (0.9m x 2m), with a surface area of 2880 sq/in (1.8m2), at 8 psi (55kPa) max cabin pressure differential, which most airliners run at, will have roughly 12 tons (102kN) ...
John K's user avatar
  • 132k

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