Off Topic > General Discussion

Skylab launch video and animation

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Peter B:
https://youtube.com/watch?v=jW_h1dtBU5Q

5 hour video of the launch and aftermath of the launch of Skylab.

Obviousman:
I didn't realise the issues they had with the S-II skirt.

JayUtah:
When the micrometeoroid shield and other structures detached from the payload during ascent, they damaged the linear shaped charge used to separate the interstage. The damage created a discontinuity in the explosive material. Because only one detonator was provided, the charge only progressed as far as the discontinuity. Ordinarily it would race all the way around the vehicle in a tiny fraction of a second. For this reason, any time these days we use the same separation method, we provide a detonator at each end of the charge. But more often we use mechanical designs that require only one small detonator that fails the mechanical attachment uniformly.

bknight:

--- Quote from: JayUtah on March 11, 2024, 10:22:16 AM ---When the micrometeoroid shield and other structures detached from the payload during ascent, they damaged the linear shaped charge used to separate the interstage. The damage created a discontinuity in the explosive material. Because only one detonator was provided, the charge only progressed as far as the discontinuity. Ordinarily it would race all the way around the vehicle in a tiny fraction of a second. For this reason, any time these days we use the same separation method, we provide a detonator at each end of the charge. But more often we use mechanical designs that require only one small detonator that fails the mechanical attachment uniformly.

--- End quote ---
Did they ever determine why the shield detached?

JayUtah:
Unanticipated aerodynamic effects.

The shield was in fact very flimsy, because it didn't need to have much structural strength to perform its task on orbit. What most people don't realize is how the shield was meant to deploy. It was supposed to spring outward and form a larger cylinder than in the stowed-for-launch configuration (with foldouts to create the larger perimeter needed).

One of the fairings for the tunnels containing cabling and other conduits down the side of the payload created a shock wave that pulled the nearby leading edge of the shield away just enough for ram air to get underneath it. Once that happens, the shield is not nearly strong enough to withstand the slipstream.

The shield was made from 22-gauge aerospace aluminum, which makes it about twice as thick as an aluminum pie plate, or about twice as thick as your HVAC ductwork. For launch, it was held tight against the lab wall by its deployment mechanism. The aerodynamic test regime had not included protrusions such as fairings.

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