5k views

### Could there ever be a fully solar powered airliner capable of transatlantic flights?

Could a new or a modified existing airliner, e.g., a Boeing 737, be fully powered by solar energy and make the normal length trips aviation-fuel powered aircraft make?
23k views

### Why do airplanes have to retract landing gear?

Why do all the airplanes have to retract their landing gear, once they reach some specific height? Why can't they simply leave their landing gear deployed all through the flight?
1k views

### Do aircraft use the majority of their fuel to overcome friction?

It was asserted (tangentially) in this question that airliners use most of their fuel to overcome frictional losses. Is that a true statement? If so, ...
3k views

### What is a ramjet?

What is a ramjet? Was it used on the SR-71 Blackbird?
14k views

### Why are propeller engines uncommon on airliners?

My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range. I assume that turboprop engines are more fuel ...
342 views

### Is multi element wing good option for slow flight airplanes?

Can we use multi element wing for slow flight planes, like F1 multi element rear wing? If we know that pressure act prependicular to the surface why this two upper elements are "almost" ...
946 views

### For a flying wing airfoil, which AOA is to consider when selecting Cl?

I'm in the process of designing a flying wing. I'm trying to keep it a small as possible, so the lift coefficient is very crucial for me. I'm currently looking at some airfoils but most of them ...
6k views

### Why is max endurance different for jet and props?

Max endurance speed is not the same for gliders, propeller planes (also for turbo prop, right?) and jet planes. While for for jet planes max endurance is at the minimum drag speed ($V_{md}$), for ...
2k views

### What is the maximum theoretical lift of a plane as a function of engine power and surface of the wings?

Maximum theoretical lift of a plane as a function of engine power and surface of the wings? I know that the maximum static thrust of a propeller turned by an engine of power $P$ can not be greater ...
4k views

### Is the maximum lift-drag ratio found at minimum drag?

Figure 10-5 of the FAA's Pilot's Handbook of Aeronautical Knowledge shows: I didn't think $L/D_{MAX}$ coincided with $D_{MIN}$. Is this Figure accurate?
546 views

### How significant is the lift induced drag contribution to total drag of aircraft at cruise speed?

How significant is the lift induced drag contribution to total drag of aircraft at cruise speed? From what I've learned so far it seems to be around 10 to 15 percent of total drag. I suspect the ratio ...
2k views

### What are typical airspeeds and lift coefficients for UAVs at different flight stages?

I've been trying (unsuccessfully) to figure out the relationship between airspeed of a fixed wing UAV at different flight stages. What I mean is, I would like to know the order of airspeeds from ...
470 views

### How do I obtain the max endurance altitude?

There are excellent explanations of the physics that determine maximum endurance speed here, here, and here. I was thinking of aircraft that have to be "on station" without an indicated altitude and ...