SkyCrane Myth??
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SkyCrane Myth??
Was the 'Crane able to have 3 blades removed and be flown for ferry's etc??. .. .I have spoken to a engineer mate of mine who works on them and he has heard the stories but seems to think it is a Vietnam era myth type of thing...... .. .Any clues??
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This story is probably transferred from the true story of the Sikorsky test flight of the CH-53A/D where 3 of the 6 blades were removed for a brief flight test program. The tests were flown in early 1975, if I remember correctly. We used the data to substantiate the emergency ferry capability of the H-53, and also to prove the flight performance of the S-76, which was being designed back then.. .. .At lighter weights, the aircraft was sucessfully hovered and flown. It shook a bit, because the N per revolution vibrations had more energy and were at a lower, more bothersome frequency, but overall, it proved that the aircraft could be safely evacuated with half its blades removed.. . . . <small>[ 04 March 2002, 02:02: Message edited by: Nick Lappos ]</small>
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A US Army instructor at Ft. Eustis, Virginia was asked what would happen if the CH-37 lost a blade. His response was that the other blades would reposition themselves and there would be no problem.. .. .Whether this is a myth or not it made the rounds at Hughes Helicopters. The story goes that a Loach pilot made an emergency landing because of a damaged blade and the attendant vibration. He supposedly removed the opposite blade and dumped all of his extra weight and with max power was able to return to base.
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Talk about removing blades, has anyone seen that wonderous piece of old black and white footage of a mysterious Russian helicopter with ONE blade? Yes, one blade and a counter-weight on the other side. It looked as though it was rotating at about 25RPM. As far as I know it was only a prototype and never flew more that a couple of test flights. It looked a bit like the body of a mil 10(harke)with bits on.
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Hughes make a very large, tip driven helicopter with 2 blades and no tail rotor in the early 50s. Only one built, as an experimental flying crane for the US Army. I think it was the XH-17. Main rotor diameter was about 130 feet (and you thought that Bell built big 2 bladed machines!).I'm told that NR was so low you didn't need a tach, you just counted seconds between blade passings. Is that the one you're thinking of?
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I saw video of that hughes, it is really wierd, looks like slo-mo. It was huge too, they show it lifting a semi. the truck just drives underneath the landing gear.
I had never heard of the need or desire to operate a Crane with 3 blades, but as Nick comments on the CH-53 programme, it is quite feasible, and apparently accomplishable (sort of glorified Whirlwind?)! <img border="0" title="" alt="[Razz]" src="tongue.gif" /> As the ship is light without a load, it would probably perform pretty well. You might have an interesting discussion with the FAA trying to get a ferry permit for it though... <img border="0" title="" alt="[Wink]" src="wink.gif" /> . .. .I could also swear that I have seen the footage of a huge single bladed, counterweighted, Hughes helicopter, but can find no reference to it anywhere.. .. .I recently saw a Hiller HOE-1 up close, it is pretty unique in having a single tail rotor blade and counterweight. Pretty funky design that thing, makes an R-22 look like a Crane! <a href="http://www.nasm.si.edu/nasm/aero/aircraft/hiller_hoe.htm" target="_blank">HOE-1</a> and <a href="http://avia.russian.ee/vertigo/hiller_hoe-1-r.html" target="_blank">here</a>. . .. .During that era, there was a definite drive to build HUGE aerial cranes. Naturally, Howard Hughes would be in the middle of this project, with a couple of real beauties as noted above; <a href="http://avia.russian.ee/vertigo/mcdonnel_crane-r.html" target="_blank">XH-17</a> and the <a href="http://avia.russian.ee/vertigo/hughes_xh-28-r.html" target="_blank">XH-28</a>. . .. .Although not really known for his success in large helicopters, Hiller even offered up yet another alien looking creature <a href="http://avia.russian.ee/vertigo/hiller_crane-r.html" target="_blank">Hiller Powerblade</a>.. .. .At the time the concept entailed helicopters up to 1 million pounds lifting capacity and snatch up returning space craft boosters in mid air! <img border="0" title="" alt="[Eek!]" src="eek.gif" /> . .. .This Russian site, is one of the best helicopter sites on the Internet <a href="http://avia.russian.ee/vertigo/helicopters.html" target="_blank">here</a>.. . . . <small>[ 05 March 2002, 07:01: Message edited by: Cyclic Hotline ]</small>
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A Russian friend recently related how an Mi-8 in Afghanistan encountered severe vibrations after being shot at from above by the Afghans. They had to land and shut down, and discovered it was because one of the 5 blades was missing about 4 feet of blade. With the Afghans closing in (and it wasn't to invite the Russians for tea, as we know), they decided to get out a hacksaw and cut off the appropriate amount from the other blades. I assume they jettisoned some other things too, but were able to get home!. .One of the many untold stories from Afghanistan.
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To: Shawn Coyle. .. .Did you Russian friend say anything about vibration? Many US helicopter blades are mass balanced to ¼”ounce to minimize vibration and oscillatory loads in the rotor system. I have heard of that being done on propellers in fact I saw it being done. In the 1947 Air Races a pilot named Howard Lilly who I believe was a NASA pilot cut several inches off of his prop on a Bell King Cobra. He ran the engine and there was a bit of vibration so he removed it and balanced it using a file to cut away the prop material until the blades were in balance. The race was won by Cook Cleland flying a Goodyear F2-G Corsair with an R-4360 up front.
Of course our good friend Mr Dushack (spelling?) went around modifying blades to facilitate installation from one type to another.. .. .He did a very nice number on converting UH-1H blades to fit the UH-1B, sawing off 11 inches from the tip, if my memory serves correctly. He must have done a good job on them, as I never noticed them when I carried out an inspection (although I have to admit, it had never even crossed my mind to look). The blades were supplied by a third party organisation, so there was no incriminating paperwork from the source which might have raised flags. I think that in the interests of productivity, that he only modified timed-out blades as well! <img border="0" title="" alt="[Eek!]" src="eek.gif" /> . .. .I only heard about it in passing when the DOM of the operation mentioned an FBI sting he had got roped into, trying to catch the conspirators in the act, but they were too sharp! They did get busted on some other scheme however and all got thrown in jail.. .. .This was the second time I had inadvertently been involved with these people, as one of my Long-Rangers had a set of Dushack blades on it when we bought it in the early 90's.
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To Lu:. .The vibrations were pretty intense from the reports, but the crew were willing to put up with them in view of the alternatives..... .Lots of other stories about innovative field repairs that happened that I'm trying to put together with this gentleman on the whole Soviet experience with helicopters in Afghanistan.
