Xref: utzoo sci.space:9569 sci.physics:5976
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!nic.MR.NET!umn-d-ub!umn-cs!ns!logajan
From: logajan@ns.UUCP (John Logajan x3118)
Newsgroups: sci.space,sci.physics
Subject: Chemical Projectile Accelerators
Message-ID: <1118@ns.UUCP>
Date: 13 Feb 89 19:30:35 GMT
Followup-To: sci.physics
Organization: Network Systems Corp. Mpls MN
Lines: 21


(Why I think) Projectiles from guns can be accelerated to speeds faster than
the speed of sound in the propelling gases:

Because the gas molecules traveling at near right angles to the direction of
travel of the projectile can strike the projectile if it has a trailing conical
section.  That is, the ratio of projectile velocity to molecule velocity
determines a slope at which an orthogonal molecule will just graze the
projectile shape as it passes.  Thus note, there is no upper limit on speed
differential, as an appropriate slope can always be found.  HOWEVER, the
greater the ratio the more normal the collision and hence the less vector
forward thrust produced.  At some point the thrust produced will fall below
other frictions and acceleration will cease.

This same description holds true for sail boats (which explains why a sail
boat can go faster at an angle to the wind than directly with the wind) and
fresh watermellon seeds squeezed between the thumb and forefinger.

-- 
- John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428  -
- ...rutgers!umn-cs!ns!logajan / logajan@ns.network.com / john@logajan.mn.org -