What the gyros do

[Andrew Dinn]

Bob Norton wrote

> If you will recall, the V-2 was launched straight up, like all
> "ballistic" missiles. It was steered during the period before
> brenschluss. The gyros provided inertial reference against which the
> radio steering telemetry was differentiated. The resulting signal
> adjusted steering vanes to control flight direction. Modern ICBM's
> use steering rockets to the same effect (steering rockets are not
> affected by variations in atmospheric density and vanes
> are). Without the gyros and the steering telemetry, the V-2 would
> have flown about 35-40 miles straight up, flipped over, and come
> down on the launcher.

Hmm, don't know where I got the idea that the gyro was used to
determine Brennschluss. The relevant passage in GR is on page 301 of
the Picador/Viking. There Pynchon describes the device which sensed
acceleration as a pendulum from which a coil was suspended in a
magnetic field.  As the rocket accelerated the coil moved sideways
inducing a current in the coil which charged a capacitor (integrating
acceleration once to obtain velocity or twice in later versions to
obtain distance travelled) and, eventually, the voltage on the
capacitor reached a reference potential which switched off the fuel
feed. I seem to remember someone writing about a gyro-based control
mechanism though (Steven Weisenburger's book maybe). Which would make
more sense since it looks to me as if a pendulum would only reflect
the horizontal component of the acceleration. e.g. if the rocket went
straight up there would be no tilt, no movement of the pendulum hence
no automatic Brennschluss.

Jody's comments about Brennschluss as a death signal are right on the
mark. But don't forget that Brennschluss is not death but the moment
of preterition. The Rocket is a living corpse from that point onwards
because it has been betrayed to gravity - a judgement from which there
is no appeal. At Brennschluss all notions of guidance or control are
discarded and the rocket enters free fall, it's course indeterminable
and random (a prize to anyone who can insert a cigarette paper between
those two terms) with the only certainty being that final delta-t.


Andrew Dinn
-----------
And though Earthliness forget you,
To the stilled Earth say:  I flow.
To the rushing water speak:  I am.