A glider like transport aircraft - possible?

[Squawk 1200]

Hi.

 

In short - my interest in gliders has sparked a question if a high aspect ratio transport aircraft would be possible from an engineering POV? The aircraft would possess a high lift to drag ratio (>25) and would be able to fly for a long periods of time and fly shorter routes with less fuel consumption. Cruising altitude would be between 45-65,000 ft with a possibility of making completely unpowered descent and landing.

 

A spy plane of simialr configuration entered service in USAF (Lockheed U-2)

 

 

 

 

[RiceAWay]

You do realize that the weight of the aircraft and LOAD has a bearing on the lift? You are speaking of being able to carry a load by soaring and that requires being able to lift off. And that the thermals necessary to soar upon must be strong enough to maintain the altitude of a soaring aircraft.

 

Two problems appear: the wings in order to carry any load at all would have to be longer than the mechanical strength of the available materials and wings of that length could not find many thermals strong enough or large enough to be able to turn rapidly enough to stay within the normal size of thermals.

 

Even the Great Albatross which is EXTREMELY light can only take off by running down hill into a wind.

 

I believe that the aircraft in your photo is a U2 and the wings were NOT for soaring but for being able to lift to very high altitudes with minimal power. The power was minimal because it traveled so slowly that the fuel capacity was necessarily large.

Edited January 24, 2017 by RiceAWay

[Country Boy]

As far back as WWII there were gliders capable of carrying small tanks. Exactly how much weight are you taliking about? And how far do you want to carry it?

[Klaynos]

Tanks carried by gliders has been done (tow launch).

 

https://en.m.wikipedia.org/wiki/General_Aircraft_Hamilcar

[Squawk 1200]

As far back as WWII there were gliders capable of carrying small tanks. Exactly how much weight are you taliking about? And how far do you want to carry it?

At the beginning may be 50-60 passengers with baggage or equivalent amount of cargo.

 

Maybe with a closed wing configuration, like the one below but with much more slender airframe (that one looks like a full blown wide body airliner) and two high bypass turbofans rather than four piston engines:

Edited January 25, 2017 by Squawk 1200

[RiceAWay]

As far back as WWII there were gliders capable of carrying small tanks. Exactly how much weight are you taliking about? And how far do you want to carry it?

These gliders had a steep angle of descent so they have to be carried up to altitude by a powered aircraft and virtually to their destination before release.

 

The OP said, " would possess a high lift to drag ratio (>25) and would be able to fly for a long periods of time and fly shorter routes with less fuel consumption." and carrying a heavy load in this manner isn't practical and I do not believe it possible with material science.

[Manticore]

 

Even the Great Albatross which is EXTREMELY light can only take off by running down hill into a wind.

 

The Marabou Stork is by no means lightweight - possibly over 9kg with a wingspan of more than 3 metres. (unconfirmed reports claim over 4 metres) - takes off from flat ground - low aspect ratio compared to an Albatross but an excellent glider (I have observed them at over 4000 feet above my home which is about 3,900 ft above sea level).