Short Wings on Supersonic A/C

[Macgyver]

Hey guys,

I read somewhere the following exert:

" There is no aerodynamic advantage (as there is in subsonic flight) to having long wings, and there are also structural as well as aerodynamic advantages in keeping the wings short."

Why is this? Why can we seemingly ignore induced drag for high speed flight?

Thanks in advance!

[barit1]

Induced drag's not ignored; it's optimized around just like any other aircraft.

But optimizing the wing aerodynamically AND structurally at such high speed takes you through parametric studies that drive you to a broader chord and shorter span. That provides internal volume to stow undercarriage and a prodigious gallonage of fuel.

[rigpiggy]

4Think F104

[barit1]

I was talking airplanes, not missiles.

:8

[chornedsnorkack]

I think it has to do with wingtip vortex.

In subsonic flight, some of the air underneath the wing escapes around the tip of the wing to create the wingtip vortex. This means loss of lift, though. Therefore, a long but thin and narrow wing is efficient compared to short but thick and wide wing - the ratio of lift to induced drag is better.

Whereas in supersonic flight, the air compressed under the wing cannot escape sideways around the wingtip - not enough time. Therefore a short and wide wing is not less efficient than long and narrow one.

[John Farley]

Macgyver

The induced drag component of total drag reduces as speed increases so is very low at high speed, hence a low aspect ratio is fine for high speed - although it can cause very high drag at low speeds.

On the sketch below line B shows how induced drag varies with speed, line A shows the profile drag and line C the total drag


http://img.photobucket.com/albums/v145/johnfarley/Drag.jpg