Nov 4, 2005, 10:29 AM
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Jumpmaster/helicopter question
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This is something i thought of after watching a helicopter jump on skydivemovies.com. Normally on a jump run you have horizontal speed to assist in separation of groups exiting is there enough forward speed in a chopper or does it just hover taking longer to dispatch each group ?. Due to exiting time for each group to open and move off, cheers.
This is something i thought of after watching a helicopter jump on skydivemovies.com. Normally on a jump run you have horizontal speed to assist in separation of groups exiting is there enough forward speed in a chopper or does it just hover taking longer to dispatch each group ?. Due to exiting time for each group to open and move off, cheers.
A helo will normally have some forward speed when dropping jumper. The size of groups are normally small and there must be more time between exits.
the small heli I jumped at Davis was going perhaps 20-25 knots. But it would only take 2-3 jumpers plus the pilot, and 2 would leave at the same time. I expect it would move a bit forward for the third. The climbout was tricky enough that it would build some time into the equation as well.
LouDiamond (D 25931)
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Nov 4, 2005, 2:58 PM
Post #4 of 7
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Normally on a jump run you have horizontal speed to assist in separation of groups exiting is there enough forward speed in a chopper or does it just hover taking longer to dispatch each group ?.
Most civilian skydiving from helicopters that hold 3 skydivers (allouette, etc) continue with a forward albeit slow speed ( est 30 knots)as it is harder to bring the helo to a hover and let people jump off. The important thing with these small helos is balance and that the skydivers leave in the manner the pilot dictates. Since most people exit as 1 staggered group to maintain the helo balance seperation isn't as big of an issue until it is time for them to track off, which is no different than any other 3 way group skydive at break off.
On larger helos( Black hawks, S-58, etc) which can hold more people and go faster, the forward speeds can be close to 90 knots if they choose to drop in that manner. Seperation would be handled like we normally do if people were leaving in different size groups and disciplines( RW, FF biggest to smallest) unless everyone leaves as one group from the helo at the same time(this is usually at altitudes closer to 10-12K). The S-58 drops around 5 k at WFFC and the combination of slow but constant forward speed ,time it takes for people to climb out and the low altitude normally spreads people out horizontally much like a static line drop does across the ground.
All choppers have an altitude limit at which they can hover "out of ground effect". With a full load most 4 to 6 place birds will not be able to hold a hover at 5,000 feet on a warm day.
Most helicopters are hard-pressed to hover (out of ground affect) at 5,000' but can easily climb twice that high if they maintain 35 to 50 mph forward speed. The secret is "translational lift." At low airspeeds, a rotor flies like a bunch of individual blades beating the air into submission, but when forward speeds exceed 40 knots, they start cooperating like one large disc.
Rob Warner, retired Sikorsky mechanic
billvon (D 16479)
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Nov 10, 2005, 9:36 AM
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>Most helicopters are hard-pressed to hover (out of ground affect) at > 5,000' but can easily climb twice that high if they maintain 35 to 50 > mph forward speed.
Yep. Which makes the recent helicopter landing on the peak of Everest all the more impressive.
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Byron Boogie 2004 .jpg
