2
$\begingroup$

I'm asking this here not because it's a question about flying a plane but because I read some engineering questions that said to bring aerodynamics questions to aviation.se for the best results.

Will a Sears-Haack body straighten itself out if "launched" sideways? Let's say it's launched from space toward the earth and hits the atmosphere at supersonic speeds. Even if it "hit" air side-on would it straighten itself out? (That is -- one of the pointy-sides now at the front) And if so would it happen in a quick/undramatic way so that the spaceship launching it would have a reasonable chance of hitting an intended destination?

If not, would the addition of fins to one end make it more likely to right itself as it hit the air?

--I guess this question boils down to: "will an object moving at high speed find and stay in its most aerodynamic orientation?" and then: "if not, will a major control surface like fins make it do so?"

$\endgroup$
  • $\begingroup$ Welcome to Aviation.SE and thanks for the interesting first question! $\endgroup$ – reirab May 9 '18 at 9:40
5
$\begingroup$

will an object moving at high speed find and stay in its most aerodynamic orientation?

No. It will most likely tumble around. With the center of gravity behind its center of pressure, a body of rotation is inherently unstable.

if not, will a major control surface like fins make it do so?

Yes. That is the reason for those large surfaces at the rear end of airplanes.

This answer is about directional stability over Mach. At supersonic speed directional stability drops with increasing Mach number.

This answer covers a similar topic; now it is about the proper location of fins at supersonic speed.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.