On Tue, 25 Jun 2002 [EMAIL PROTECTED] wrote:
> Aerodynamic slipstream vibration can interact with the engine bells,
> introducing transverse modes. Keep the vehicle clean and the engine bells
> out of the slipstream.
More generally: the payoff, in simpler behavior and easier analysis, for
a "clean" vehicle, with a simple shape and no lumps and bumps, is high.
The aerodynamic analysis of the Saturn V was complicated *enormously* by
all the external plumbing runs, wiring tunnels, equipment housings,
structural reinforcements, etc etc etc. And some of that stuff had really
significant effects, e.g. a 5-10% increase in side forces due to winds,
and quite a bit of roll torque from asymmetric bumps.
This is doubly so for reentry. After great difficulties predicting the
aerodynamic behavior of the Block I Apollo CM, it was decreed that the
Block II CM would have no, repeat no, lumps and bumps -- that all ports,
antennas, etc. had to be flush with the surface.
Henry Spencer
[EMAIL PROTECTED]
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