3 ms·

Good thing they didn't have any on-board guidance systems back then.

bendykstra 11y ago
The V2 had a guidance computer. Early rockets were purely inertial while some later rockets also rode radio beams to their targets.
- arethuza 11y ago
  The Germans had guided weapons in WW2 - notably the anti-ship Fritz X guided bomb (not powered): https://en.wikipedia.org/wiki/Fritz_X https://en.wikipedia.org/wiki/Fritz_X
KMag 11y ago
The V2 used pendular integrating gyroscopic accelerometers (PIGAs) and gyroscopes for guidance. As far as I know, the V2 was the first use of the PIGA. Descendants of the V2 guidance systems were used by the Apollo moon missions and several US intercontinental ballistic missiles. The PIGA is actually a pretty cool piece of machinery. You have a free-swinging balance arm that has a mass and a gyroscope on it. The gyroscope's axis of rotation is aligned with the balance arm. An electric motor spins the whole balance arm in a direction perpendicular to both the gyroscope's axis of rotation and the axis about which the balance is free to rotate. So if you remember from Freshman physics, you have a rotational momentum and an applied torque, the resultant torque is the cross product of the two (in other words, a torque in the direction the balance moves freely). An analog controller keeps the electric motor spinning at a rate that keeps the balance beam level. So, the rate the electric motor is turning is proportional to acceleration in the direction of the electric motor's axis. Thus, the integral of the acceleration is proportional to the integral of the rotational velocity of the electric motor. In other words, the number of revolutions of the electric motor is proportional to the velocity of the rocket (relative to free-fall). A simple revolution counter is sufficient to cut off the engine's fuel flow once the rocket has reached a given velocity. (Source: I interned at Draper Lab, which made the Apollo guidance systems and several ICBM guidance systems. I walked by an Apollo PIGA in a display case every morning.)
- vermontdevil 11y ago
  Fascinating. Thanks for sharing. I meant in terms of GPS-based which would improve the accuracy. Sorry for being a bit flippant with my original comment.
- omegant 11y ago
  Thank you! Is there any book that talks about this system in detail?
- dTal 11y ago
  That was a very clear description and highly interesting. Thanks for sharing.

The V2 had a guidance computer. Early rockets were purely inertial while some later rockets also rode radio beams to their targets.

arethuza 11y ago
The Germans had guided weapons in WW2 - notably the anti-ship Fritz X guided bomb (not powered): https://en.wikipedia.org/wiki/Fritz_X https://en.wikipedia.org/wiki/Fritz_X

KMag 11y ago

The V2 used pendular integrating gyroscopic accelerometers (PIGAs) and gyroscopes for guidance. As far as I know, the V2 was the first use of the PIGA. Descendants of the V2 guidance systems were used by the Apollo moon missions and several US intercontinental ballistic missiles. The PIGA is actually a pretty cool piece of machinery. You have a free-swinging balance arm that has a mass and a gyroscope on it. The gyroscope's axis of rotation is aligned with the balance arm. An electric motor spins the whole balance arm in a direction perpendicular to both the gyroscope's axis of rotation and the axis about which the balance is free to rotate. So if you remember from Freshman physics, you have a rotational momentum and an applied torque, the resultant torque is the cross product of the two (in other words, a torque in the direction the balance moves freely). An analog controller keeps the electric motor spinning at a rate that keeps the balance beam level. So, the rate the electric motor is turning is proportional to acceleration in the direction of the electric motor's axis. Thus, the integral of the acceleration is proportional to the integral of the rotational velocity of the electric motor. In other words, the number of revolutions of the electric motor is proportional to the velocity of the rocket (relative to free-fall). A simple revolution counter is sufficient to cut off the engine's fuel flow once the rocket has reached a given velocity. (Source: I interned at Draper Lab, which made the Apollo guidance systems and several ICBM guidance systems. I walked by an Apollo PIGA in a display case every morning.)

vermontdevil 11y ago
Fascinating. Thanks for sharing. I meant in terms of GPS-based which would improve the accuracy. Sorry for being a bit flippant with my original comment.
omegant 11y ago
Thank you! Is there any book that talks about this system in detail?
dTal 11y ago
That was a very clear description and highly interesting. Thanks for sharing.