[AR] Re: shuttle SRBs (was Re: Re: Phenolic regression rate)
- From: Craig Fink <webegood@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 6 Feb 2018 10:12:38 -0600
On Sat, Feb 3, 2018 at 7:12 PM, Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
Despite the low launch temperatures, the Challenger crew might have
lived if their O-rings had been leak-tested at 50psi instead of 200psi.
They also may have survived if Roll had been properly decoupled from Yaw
during load relief in Flight Control. While first stage guidance used Pitch
and Yaw (vs velocity) tables, Roll was set to single value 180 deg at tower
clear. This is fine from a guidance standpoint, but Flight Control had a
Load Relief function that was sloppy. All the large and excessive SRB
gimbaling on ascent was roll related caused by the Flight Control Load
Relief function reacting to and yawing into the crosswinds. The damaged SRB
o-ring at the high load strut attachment point opened up again at the
largest wind induced SRB gimbal deflection (mostly roll) that the vehicle
would have experienced that day. During load relief, Roll control should
have been used to zero roll rates and roll attitude errors from heads
down,180 degrees, should have been allowed to drift as the vehicle yawed
into the gusts (y-axis acceleration error).
--
Craig Fink
WeBeGood@xxxxxxxxx
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