- 12/07/2017 at 11:59 #67278Les HammondParticipant
When dropping parachute troops from aircraft, would the transport plane be flying into the wind so as to be able to reduce its airspeed?
I am guessing that wind direction might/probably will be different at ground level compared to jump height so there might be/will always be some kind of up/downwind dispersion.
- This topic was modified 4 years, 2 months ago by Les Hammond.
6mm France 1940
https://www.facebook.com/groups/386297688467965/12/07/2017 at 16:36 #67303John D SaltParticipant
I think you mean groundspeed, rather than airspeed.
I have never heard of the idea of flying into wind as you suggest. In a military drop this would have to be considered during planning, and so could only account for the expected direction and magnitude of prevailing winds, which might differ from conditions on the day.
The wind is unlikely to be much different on the ground from what it is at the drop height, since military drops are from much lower heights than sports parachuting drops. My one and only drop was from 2,500 feet, and I believe they are now allowed from 2,000 in the UK; military drops would be more like 500 feet, or as low as 300. This minimises both time in the air (I gather that 300 feet means there is only just enough time for the canopy to deploy) and dispersion on the ground. As well as the short drop distance, the wind is unlikely to be very high if a drop is taking place at all. My solitary drop used a double-L 15-knot chute, and would not have been used in winds higher than 15 knots. WW2 chutes were more primitive. As I understand it, with British and American style chutes, where the suspension lines attach to risers on each shoulder of the harness, the jumper could grab a handful of lines and squeeze them together, thus giving the canopy some degree of steerability, for which one would use the control toggles on a modern canopy. German and Italian chutes had a single riser, so the unfortunate parachutist was suspended by the scruff of the neck and had no control over the canopy at all. I do not know what Russian and Japanese canopies were like, but I imagine like the Italian (I believe lots of parachute designs were based on the Italian “Salvatore” pattern). Probably this explains why German and Italian parachutists seem to be more generously equipped with padded clothing than their Anglo-American equivalents, who had a bit more control over how they landed.
I expect that the main factor governing the spread of a stick (next to dodgy navigation by the aircraft) is the speed with which the jumpers do their door drill. There is also the question of the number of doors. Again, modern equipment is better than it was in WW2; a Herk can have people jumping out of both sides and off the rear platform simultaneously, and it doesn’t take long to get everyone out of the aircraft. Many years ago, during a TA exercise on a crowded training area (you know it’s busy when you have a side firefight with people who aren’t even in the same exercise) I had the privilege of watching a tactical drop of a company-sized group from close range (no idea whose exercise they were in, but not ours). Timed on my digital watch (which in the 1970s humans still thought were pretty neat) it was less than five minutes from the first sound of the three Herks to the company moving off the DZ in tactical formation (and, a bit of a Para flourish, with their red hats on, just in case there was any doubt who they were). I also saw the Paras drop on Ginkel Heath on the 50th anniversary of Arnhem, in marginal conditions — the winds were gusty enough for the drop to have been cancelled in normal circumstances, and the tandem drop scheduled by a 90-year-old veteran who had been blinded during the battle was postponed until the next day. They were not as low or as quick as I had seen them before — I doubt they were trying to be — and the ambulances were busy on the DZ afterwards, but I do not recall there being any problem with the drop being scattered.
Of course it’s all different if you are doing funny SF stuff with HALO or the like, but in that case you probably have a ram-air canopy that you can drive a very long way from the drop point if you have to.
All the best,
John.12/07/2017 at 19:08 #67323Les HammondParticipant
As usual, more info than expected. Thanks!
6mm France 1940
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