Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bloom-beacon!usc!venera.isi.edu!raveling
From: raveling@venera.isi.edu (Paul Raveling)
Newsgroups: sci.space.shuttle
Subject: Re: Atlantis is home!
Message-ID: <8537@venera.isi.edu>
Date: 31 May 89 18:54:47 GMT
References: <272@skipper.dfrf.nasa.gov> <9090001@hp-lsd.HP.COM> <4453@ttidca.TTI.COM> <6949@bunny.GTE.COM> <8465@venera.isi.edu> <4499@ttidca.TTI.COM>
Reply-To: raveling@venera.isi.edu.UUCP (Paul Raveling)
Organization: Information Sciences Institute, Univ. of So. California
Lines: 38

In article <4499@ttidca.TTI.COM> hollombe@ttidcb.tti.com (The Polymath) writes:
>In article <8465@venera.isi.edu> raveling@venera.isi.edu (Paul Raveling) writes:
>}	Also note that these shock waves form ahead of and behind the
>}	object.  An form with a relatively pointed nose, like an F-104,
>}	has a relatively large distance between its leading shock wave
>}	and the nose itself; this produces minimal drag due to feeding
>}	energy into the shock wave.  A relatively blunt nose, such as
>}	the shuttles, will generate its shock wave much closer to, or even
>}	even on, the nose, and will produce much higher drag.
>
>This is the opposite of what I was taught (and saw demonstrated).

	I believe you're right.  A blunt nose should logically produce
	a relatively larger zone of high pressure in which the flow
	goes subsonic between the shock wave and the nose.

	Pardon my rusty brain; give me a sailplane that's at least
	transonic & I'll start brushing up.

>Shock waves tend to attach to a sharp leading edge and precede a blunt
>one.  You can demonstrate the effect in water by observing the bow wave of
>a boat with a rounded bow in the water vs. one with a pointed bow.
>
>Don't flame if you haven't tried it.

	I used to own a boat with a pointed bow (a Soling) & agree
	completely in the context of displacement hulls.  Planing
	hulls aren't germane to the analogy, but hydrofoils would
	make an interesting study.  Does anyone know of research
	into hydrofoil section optimization?

	Now if only this worked on the freeway, where flow is viscous,
	even if not hypersonic, we could design and sell a lot of cars.


----------------
Paul Raveling
Raveling@isi.edu