To: Speechless Two
The system you described was the same as that used in the HSS-1 however the equipment manufacturer might have been different. If memory serves me correctly the SONAR system used in the HSS-1 was made by Texas Instruments. I was not inferring that the SONAR operator wiggled the line to the ball. I meant that if the ball were dropped a person on the ground could move the helicopter by moving the line in relation to the drift forks. This could also be done on the Wessex because of the systems design. I believe they had a similar ground control capability on the Sky Crane for positioning over a load.
I don’t know if you are familiar with the rigging of the helicopter but on the HSS-1 the ASE was placed on a fixture that reflected the hover position of the helicopter. 3-degrees tail down and (I hope this is right as it has been many years since I did this) 7-degrees left wheel down. In this position and with the helicopter level the error signal from the ASE was nulled out so that in a hover there would be no error signal. The SONAR system would reflect the hover position in the hover due to the displacement of the drift forks and the SONAR operator would null that signal out so the helicopter could remain stationary. Then, if the drift forks were displaced due to water movement below the helicopter, the drift forks would sense this movement and send an error signal to the ASE. The ASE would then generate a signal to the Aux.servo and move the helicopter with the water flow below it keeping the SONAR ball under the helicopter. All of this from the mind of an aging old fart (71 years old). The last time I saw one of these helicopters was in 1956.
[ 13 February 2002: Message edited by: Lu Zuckerman ]</p>