[FPSPACE] Soyuz DM role during ballistic entry profile

[Jim Oberg]

Igor, I don't think it was Soyuz DM guidance that created
the hi-G load in 1975. The booster shut-off at that stage in
the ascent was so much short of orbital velocity, the ballistic
descent arc grew steep very quickly, well before main 
aero-braking. 

This would tend to rapidly bring the spacecraft down into
thicker air while its velocity was still very high -- too high for
that air density, without the result of excessive drag and
hence deceleration. 

Now this is speculation on 'general principles', from the point
of view of 'flight dynamics', the console position next to mine
in the 'Trench' in the MCC. I also learned the general theory
of abort profiles while on the STS-1 ascent team leading up
to the April 12, 1981, mission. I would be surprised if there
even is any desired lift vector during a contingency launch abort 
entry since there is likely to be no selected landing point to aim for --
it would be different for every different second of the ascent profile. 

That makes me guess that such a descent would auto-select null-steering 
rolling, to aid in emergency tracking and impact point prediction.

But this is all a series of 'informed guesses' from outside the
real Soviet program, and they are subject to on-the-scene
knowledge of actual procedures and results -- real data that
you and your team have demonstrated, time and time again,
that you have excellent access to.  

----- Original Message ----- 
From: "Igor Lissov" <lissov-i at yandex.ru>
To: <fpspace at friends-partners.org>
Sent: Friday, April 25, 2008 3:37 PM
Subject: Re: [FPSPACE] Soyuz DM role during ballistic entry profile


> Charles,
> 
>> And as Antonin notes, it is a bad day when the lift vector is "down".
>> Does anyone know what the g-pulse looks like in that case, and also the
> thermal load?
> 
> It's exactly what happened to Vasiliy Lazarev and Oleg Makarov
> on April 5, 1975. They have got some 21g.
> 
> Igor Lissov
> 
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