Exploring the Unknown: Selected Documents in ... - The Black Vault

Exploring the Unknown 233
retrofits on this flight. I did not notice any gross errors in attitude that persisted
throughout retrofire. There was some wandering, but I feel that it was balanced
out pretty well.
The initiation of retrofire was just a little bit late, although retrosequence
came on time. I got the countdown from the California Cap Com. I waited one
more second, which was 99:59:59 and did not get retrofire. I punched the manual
retrofire button and one or two seconds after that I felt the first retrorocket fire.
I expected a big boot from the retrorocket. But the deceleration was just
a very gentle nudge. The sound of the rockets firing was just audible. Retrorocket
Two fired on time, Retrorocket Three fired roughly on time. Each rocket gave
me a sensation, not of being pushed back toward Hawaii as reported by John
Glenn, but of being slowed down in three increments. So that by the time the
retroacceleration was over, I felt that there was just enough deceleration to bring
the spacecraft to a stop. I felt that, if I looked down, I would see that the obvious
motion that I had seen through the window and the periscope before retrofire
had stopped. But, of course, it had not.
I put three ‘arm’ switches on at this time. Retropack jettison occurred
on time and the periscope came in on time. At this time I noticed my appalling
fuel state, and realized that I had controlled retrofire on manual and fly-by-wire. I
went to rate command at this time, and tried manual and rate command, and got
no response. The fuel gauge was reading about 6 percent, but it was empty. This
left me with 15 percent on the automatic system to last out the ten minutes to .05g
and to control reentry.
If the California Cap Com had not mentioned the retroattitude bypass
switch, I think I would have forgotten it, and retrofire would have been delayed
considerably longer. He also mentioned an Aux Damp reentry which I think I
would have chosen in any case, but it was a good suggestion to have. He was worth
his weight in gold for just those two items.
The period prior to the .05g was a harried one, because I did not know
whether the fuel was going to hold out. The periscope [3-4] was retracted. The
attitude indicators were useless. The only attitude reference I had was the window.
I did not have much fuel to squander at this point holding attitude. I did use it,
gingerly, trying to keep the horizon in the window so that I would have a correct
attitude reference. I stayed on fly-by-wire until .05g. At .05g I think I still had about
15 percent reading on the autofuel gage.
I began to get the hissing outside the spacecraft that John Glenn
mentioned. I feel that the spacecraft would have reentered properly without any
attitude control. It was aligned within 3 or 4 degrees in pitch and yaw at the start
of the reentry period. My feeling is that the gradual increase of aerodynamic
damping during the reentry is sufficient to align the spacecraft properly.
Very shortly after .05g I began to pick up the oscillations on the pitch
and yaw rate needles. At this time I think roll rate was zero, or possibly one or
two degrees. The spacecraft oscillated back and forth about zero, just the way the