Exhaust Distribution

[Jens Schweikhardt]

hello, world\n

the behavior of exhaust gases is remarkably different at atmospheric
pressures and at lower pressures or vacuum. One example where this
becomes obvious is on pictures like KSC-69PC-413 (http://
www.hq.nasa.gov/office/pao/History/alsj/a11/ap11-KSC-69PC-413HR.jpg)
where the luminous exhaust gas has made its way *in* the Saturn V's
flight direction for what appears to be almost half the length of the
third stage.

What effect exactly is causing this?
Is it depending on propellant?
Are stages especially prepared to withstand such effects?
Has this effect been predicted or was it a surprise to rocket
engineers the first time it was observed (probably way before the days
of Apollo)?

Thanks for any insight!

Regards,
Jens

[Damon Hill]

Jens Schweikhardt <use...@schweikhardt.net> wrote in news:8943d9c4-f0f5-
47a9-88db-1...@t13g2000yqt.googlegroups.com:

As I understand it, this effect is due to aerodynamics; a shock wave
off parts of the rocket create a low-pressure area into which exhaust
gases can flow. The worst effect is usually burnt paint, but the
same ducting effect in engine clusters can damage engines that are
not adequestly insulated.

--Damon

[M Kramer]

On Aug 16, 11:57 am, Jens Schweikhardt <use...@schweikhardt.net>
wrote:

It is said that von Braun was surprised and alarmed by the Saturn
flame creep.