[FPSPACE] Soyuz touch down

[Geert Sassen]

Yes, if we assume the 'hole' is the point of original impact (and it 
looks very much like it) then it looks to me like the softlanding 
retro's did not fire and the steppe fire was caused by the severing of 
the parachute lines or just by the heat of the DM itself. Taken into 
account the winddirection, any other explanation would have caused the 
fire to start somewhere from the bottom of the DM or close to the 'hole' 
but there is no burn damage anywhere near that region.

The bottom headshield is released some 2-3 km up, shortly after the 
parachute system switches from single point suspension to dual point 
suspension. At that point also the softlanding retro's are armed and the 
alpha scattering radar is switched on. Could it be that the retro's 
fired at that moment or shortly after, while still high up in the air 
(as happened during the TM 25 landing)? This would explain the smoke in 
the DM during the parachute descent.

But this is all just speculation based on the pictures of the landing, 
we will wait and see what the final report is.

Charles Vick wrote:
> I would suggest that it hit the ground in that hole area sideways and was
> dragged by the parachute flipping it on its side and that the cord
> detonation to sever the parachute probably set the grass fire off therefore
> the full benefit of the retro's was not fully there at impact
>
> -----Original Message-----
> From: fpspace-bounces at friends-partners.org
> [mailto:fpspace-bounces at friends-partners.org] On Behalf Of Geert Sassen
> Sent: Friday, May 02, 2008 11:26 PM
> To: fpspace
> Subject: [FPSPACE] Soyuz touch down
>
> I'm still puzzling a bit regarding the april 19 landing and I'm 
> wondering exactly how rough was the actual touch down.
>
> If you look at several of the pictures taken after landing (for instance 
> http://a52.g.akamaitech.net/f/52/827/1d/www.space.com/images/080423-exp16-so
> yuz-02.jpg 
> ) there seems to be a kind of 'hole' or 'dent' or whatever in the ground 
> some three or four meters upwind of the location of the capsule (wind 
> direction can be viewed from some flags and also from the fact that 
> helicopters will normally land pointing into the wind), other pictures 
> show officials looking at this 'crater' and on the bottom of the DM a 
> lot of sand can be seen, so it looks like this is the position were the 
> capsule hit the ground, then bounced up and landed again on its side 
> several meters further downwind.
>
> The weird thing however is that it was mentioned the softlanding rockets 
> caused a small steppefire (not unusual, this has happened before), which 
> also burned the parachute (which we can assume came down downwind from 
> the DM). However, the only 'burn-marks' on the steppe start apparently 
> several meters downwind from the location of the DM (in the direction of 
> the hatch), there is no sign of any burn damage anywhere near the 'dent' 
> and neither is there any burn damage of the grass anywhere near the 
> bottom of the DM (there is a lot of sand on the bottom of the DM, but 
> the grass around it seems unscatched), the apparently area of scorched 
> and burned grass starts some meters downwind from the hatch.
>
> Unexplained as yet is also the smoke in the cabine, which seems to have 
> started during the parachute decent. Assuming an overheating panel, they 
> switched off some instruments, but what exactly was overheating (of 
> short circuiting?) and what exactly did they switch off.
> Remember two important events happen shortly prior to the actual touch down:
> 1) the shock absorbers of the seats are activated, this caused the seats 
> to 'rise' up (crew almost touching the instrument panel), and enables 
> the seats and shock absorbers to withstand the force of the actual 
> landing, if these shock absorbers are not activated landing will be very 
> rough.
> 2) the soft landing rockets fire close above the ground.
> Failure of any of these items can cause a very rough landing and 
> injuries as sustained by Yi
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