Helicopter drops large air conditioning unit onto Oakland street 10Jan2021
Originally Posted by [email protected]
As I have had explained to me - thanks John - the rear facing pilot doesn't have mechanical controls but has a system giving 10% AFCS authority.
Anyone familiar with the Sea King AHT (auxiliary hover trim) will understand the idea.
As with the AHT, there is a verbal handover of control with the forward pilot following through on the mechanical controls while the load is positioned/lifted and then taking control for the transition.
Anyone familiar with the Sea King AHT (auxiliary hover trim) will understand the idea.
As with the AHT, there is a verbal handover of control with the forward pilot following through on the mechanical controls while the load is positioned/lifted and then taking control for the transition.
Yes, the same system that gives the crewman in the back of a Sea King 10% authority
Avoid imitations
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Amazing that the little fan in the last picture can move the whole aircraft around......
Don't know what changes have been made to underslung gear since my time, but Whirlwind underslung detail at Tern Hill mid 60s - hooked up and checked, sent off on circuit. Visual check on return approach - no load. Pilot totally unaware and reluctant to land believing load still attached. Eventually convinced him and checked hook - support bar open ... but over-centre lock still closed!! Cancelled the detail and consulted armourers - "Can't happen , impossible" They insisted that it MUST have been the ground contact on touch-down which closed the latch. I KNEW this was not so ! Some 18 months or so later, it happened again. This time I kept the aircraft hovering and had it hover-taxy back to the pan and had the armourers look at it before touch-down. Amazed and puzzled - in theory there is a geometric lock which couldn't allow it to happen. It DID.
Never found the answer.
Never found the answer.
Just to clarify: the rear seat collective was mechanical and linked mechanically to the front seat collective.
With regard to the =/-10% AFCS control authority from the S-61 AFCS. The A model's AFCS did replicate ( except for gains of course ) the 61 architecture, but the B model was updated and mostly reflected the RH-53 system, again, except for the gains. In the B application, the cyclic trim beeping to extend authority was automatic. What the pictures do not show is that there was an SH-3 type doppler hover/AFCS crosspointer indicator, with the vertical and horizontal bars reflecting the roll and pitch inputs, and full scale was 10%. Yaw axis inputs were shown on a pointer that went left and right across the bottom of the indicator. Again,: full scale was 10%. The rear seat pilot also had a torque and a cable hook load indicator mounted on that lower rim of the plexiglass to his left front.
Writing this brought to mind a rear seat story that got back to SA during the later stage of the Vietnam conflict and which in fact was partially responsible for a flight control load stabilization test program initiated by the Army.
A Ch-54 was flying a D8 caterpillar at night, in rain.Control inputs by the crew started the load swinging, and their attempts to lessen the amplitude only aggravated it*. Finally gave up on that and attempted to jettison the load. Neither the electrical release nor the cable cutter functioned. They of course had initiated a descent ( no rad alt in the 54 ). In desperation, the crewman in the back got out his M-16 and attempted to hit the cable. Used up his ammo in vain.They eventually hit the ground with the load and all survived. The Cat and 54 did not.
* It is sort of counter-intuitive, but taking ones hands off the cyclic in a ship with attitude hold, and which has a swinging external load, esp laterally, can actually result in the AFCS aggravating the lateral load swing amplitude. We confirmed that in coming up with the CH-54 Load Stabilization system for the Army. They never bought it, and as I've noted to several folks-not sure if I've mentioned it here-the Army, since they funded that development, gave the technology to Boeing for their HLH proposal. Quite legal.
With regard to the =/-10% AFCS control authority from the S-61 AFCS. The A model's AFCS did replicate ( except for gains of course ) the 61 architecture, but the B model was updated and mostly reflected the RH-53 system, again, except for the gains. In the B application, the cyclic trim beeping to extend authority was automatic. What the pictures do not show is that there was an SH-3 type doppler hover/AFCS crosspointer indicator, with the vertical and horizontal bars reflecting the roll and pitch inputs, and full scale was 10%. Yaw axis inputs were shown on a pointer that went left and right across the bottom of the indicator. Again,: full scale was 10%. The rear seat pilot also had a torque and a cable hook load indicator mounted on that lower rim of the plexiglass to his left front.
Writing this brought to mind a rear seat story that got back to SA during the later stage of the Vietnam conflict and which in fact was partially responsible for a flight control load stabilization test program initiated by the Army.
A Ch-54 was flying a D8 caterpillar at night, in rain.Control inputs by the crew started the load swinging, and their attempts to lessen the amplitude only aggravated it*. Finally gave up on that and attempted to jettison the load. Neither the electrical release nor the cable cutter functioned. They of course had initiated a descent ( no rad alt in the 54 ). In desperation, the crewman in the back got out his M-16 and attempted to hit the cable. Used up his ammo in vain.They eventually hit the ground with the load and all survived. The Cat and 54 did not.
* It is sort of counter-intuitive, but taking ones hands off the cyclic in a ship with attitude hold, and which has a swinging external load, esp laterally, can actually result in the AFCS aggravating the lateral load swing amplitude. We confirmed that in coming up with the CH-54 Load Stabilization system for the Army. They never bought it, and as I've noted to several folks-not sure if I've mentioned it here-the Army, since they funded that development, gave the technology to Boeing for their HLH proposal. Quite legal.
The longest underslung sorties I have done were in the Solomon Islands. There was a weekly requirement to resupply the police station on Rennel Island, some 135 N.M. south of Honiara, with diesel and rations. There was no fuel available at Rennell so the AS 332L we were using had to carry return fuel. This made it quite heavy. Five or six drums of diesel plus all the supplies brought the AUW to the maximum external load weight of 9.100kgs or 20.000lbs. Another drawback was a range of large hills on the south coast which went up to 5,000 ft. plus.
The net with the drums was attached to an 80 ft. strop so that and the net gave you enough height when to took up the load to jettison it and recover to land straight ahead OEI. When you took the weight the 30 degrees ambient ensured that both engines were knocking their respective 100% torque limits. However, by talking to the aircraft nicely it could be persuaded to advance into forward flight.
Captain’s brief: Should we lose an engine in the hover or before 45 knots we will bin the load and land straight ahead. After 45 knots we will see if we can hang on to it, if not we bin it. After 70 knots we will hang on to the load, fly it over the beach and then we will bin it.
When settled in the climb we turned south and there was this range of hills with their cumulus necklaces. We would climb at 70 knots and at 5,000 it would stop climbing. This was where lots of practice at cloud dodging in Borneo came in useful; reading the wind, escape routes etc.etc., the difference being that then I didn’t than have a 100 ft, conker hanging below me.
When we were through the gaps and over the sea we could descend to 1,000ft. and the aircraft would settle at 90 knots, no faster. Engage the autopilot, feet up, fags out and sit there for an hour before Rennel Island came up. The drop off and unload was normal though you couldn’t hang about because of your fuel. Back across the sea and sort out a way through the even bigger and thicker clouds before you ran out of fuel.
Same again next week.
The net with the drums was attached to an 80 ft. strop so that and the net gave you enough height when to took up the load to jettison it and recover to land straight ahead OEI. When you took the weight the 30 degrees ambient ensured that both engines were knocking their respective 100% torque limits. However, by talking to the aircraft nicely it could be persuaded to advance into forward flight.
Captain’s brief: Should we lose an engine in the hover or before 45 knots we will bin the load and land straight ahead. After 45 knots we will see if we can hang on to it, if not we bin it. After 70 knots we will hang on to the load, fly it over the beach and then we will bin it.
When settled in the climb we turned south and there was this range of hills with their cumulus necklaces. We would climb at 70 knots and at 5,000 it would stop climbing. This was where lots of practice at cloud dodging in Borneo came in useful; reading the wind, escape routes etc.etc., the difference being that then I didn’t than have a 100 ft, conker hanging below me.
When we were through the gaps and over the sea we could descend to 1,000ft. and the aircraft would settle at 90 knots, no faster. Engage the autopilot, feet up, fags out and sit there for an hour before Rennel Island came up. The drop off and unload was normal though you couldn’t hang about because of your fuel. Back across the sea and sort out a way through the even bigger and thicker clouds before you ran out of fuel.
Same again next week.
I believe the frame grab from video is misleading A slow mo shot allows the viewer to follow the left hand cables as they fall and whilst the compression makes it tricky to see the detail, they appear slack, but unbroken.
Mjb
Mjb
There is a reverse angle video on twitter that clearly shows an unobstructed views of the cables, which appear to be undamaged, against a blue sky.
Search twitter for Rudi Tcruz @ meatisburger
Credit: Gabriel Tcruz
Search twitter for Rudi Tcruz @ meatisburger
Credit: Gabriel Tcruz
