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### Why can't jet engines operate with supersonic air and how do they slow it down?

Typically jets cannot operate when intake airflow is supersonic relative to the engine. Why is this so? Also, why are scramjets able to use supersonic air? To slow down the air to subsonic speeds, ...
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### Why are many jet aircraft designed to cruise around FL350-370?

If the flight distance permits, the B737-800 will cruise at FL350, the A320 a little bit higher... Flying at FL370. Photo: Live from the Flight Deck by GolfCharlie232 (reframed) Elements such as: ...
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### What is a high speed stall?

I'm told that planes can actually stall when the airflow over the wing goes past Mach 1? Why does this happen and how do you design an aircraft to avoid it?
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### How high can propeller airplanes fly?

Is there a maximum height a propeller airplane could fly? Some lower bounds for maximum flying altitude: 12,000m (39,370ft): Antonow An-70, produced 1994 12,310m (40,387ft): Lockheed Martin C-130J ...
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### What are the limiting factors for high altitude planes (e.g: U2 or SR71) preventing them from going higher?

I'm curious as to why planes like the U2 Dragon Lady and the SR71 Blackbird couldn't fly higher. What physical constraint set their operational ceiling? Pilots wore spacesuits, so that wasn't the ...
904 views

### Are there any aircraft designed to operate between an altitude of 50-80km?

Aircrafts operating at high altitude falls into several categories: Wings with high aspect ratio (Global Hawk, TR-1, Scaled Composite Proteus,...) High velocity aircraft (Concorde, A-12, X-51,...) ...
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### Is the climb rate different for short-haul flight and long-haul flight?

A short-haul flight does not spend much time in its cruise level (let's say less than two hours). Thus, it is important to rapidly reach the optimal flight level and I think this kind of aircraft ...
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### I'm thinking of building a balloon-launched glider, is this idea plausible?

So, I know nothing about aviation. I'm a student studying maths and computing and I feel like building a high altitude glider controlled by a Raspberry Pi and Arduino as a personal project. First ...
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### Why would a Su-25, which has more power and is much lighter than an A-10, only fly half as high?

On the web, on several sites, the A-10 is listed with a ceiling of 14 km, the Su-25 with 7 km, although there is data that puts the height for the Su-25 at 10 km. Nevertheless, why would the Su-25 ...
650 views

### What should be the minimum time spent in cruise (for e.g. a B737)?

Having a short sector to fly, it would not be convenient to climb all the way up to the best cruise altitude, since the time in climb would burn more fuel than that necessary for a flight at lower ...
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### What are the limiting factors when flying a model UAV plane to high altitude?

Setting aside the likely legal factors for a moment, what are the limiting factors when flying a model plane to high altitude? As I see it these could be: Battery power consumption - Model planes ...
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### At what altitude does aerodynamic forces become negligible?

If I sail on a boat from North to South the boat will be dragged by the oceans which it floats on, and the oceans are dragged by the Earth. Now when you go higher let say 10 km an airplane will also ...
121 views

### What is the background of the maximum altitude formula?

This question What determines the maximum altitude a plane can reach? has a formula at Peter Kämpf's answer : $$\rho_{min} = \frac{2\cdot m\cdot g}{(Mach^2 \cdot c_L)_{max}\cdot a^2\cdot S}$$ Does ...