mcgrath@nprdc.navy.mil (James McGrath) (04/07/89)
From: mcgrath@nprdc.navy.mil (James McGrath) Helicopters flying nap-of-the-earth (NOE) have been downed by striking power lines and other high wires. It seems logical that one might deliberately string wires across passes, saddles, or even between tall trees as a means of defense or interdiction against NOE air operations. Does anybody know whether such measures would be effective and whether they have ever been used?
gahooten@ames.arc.nasa.gov (04/08/89)
From: gahooten@ames.arc.nasa.gov In article <5480@cbnews.ATT.COM> mcgrath@nprdc.navy.mil (James McGrath) writes: > > >From: mcgrath@nprdc.navy.mil (James McGrath) >Helicopters flying nap-of-the-earth (NOE) have been downed by striking >power lines and other high wires. It seems logical that one might >deliberately string wires across passes, saddles, or even between tall >trees as a means of defense or interdiction against NOE air operations. >Does anybody know whether such measures would be effective and whether >they have ever been used? I don't know of any incident that has wires to catch NOE helicopters, but Barrage balloons were (of course) used effectively during WWI and II to make planes bomb from higher altitudes. They were more effective in WWI. The use on Helicopters is interesting, it would probably be easier to use a type of Barrage Balloon rather than stringing across the gorge or valley. This eliminates the need to anchor it in two places and support the full weight of the cable hanging across the distance. Prevents sagging, and is more mobile. Milimeter wave radar is being improved to dectect things like power lines. This might limit the effectiveness of this tactic. It shows up as a wavy line on a HUD in experimental AC I've seen. Greg [mod.note: This reminds me of various WWII-era rockets, designed to deploy a series of wires, or ribbons, suspended by a parachute, for AA use. The British actually deployed these in the form of their UP (unrotated projectile) lauchers; a fire in a UP ammo locker preceded the explosion of HMS Hood (though it is not believed to have been the cause of same) Also, a similar (but more summary) reply was received from MJackson.Wbst@Xerox.COM, who wrote: > >Barrage balloons. > >Mark > - Bill ]
bsmart@uunet.UU.NET (Bob Smart) (04/08/89)
From: vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET (Bob Smart) In article <5480@cbnews.ATT.COM>, mcgrath@nprdc.navy.mil (James McGrath) writes: > > > From: mcgrath@nprdc.navy.mil (James McGrath) > Helicopters flying nap-of-the-earth (NOE) have been downed by striking > power lines and other high wires. It seems logical that one might > deliberately string wires across passes, saddles, or even between tall > trees as a means of defense or interdiction against NOE air operations. > Does anybody know whether such measures would be effective and whether > they have ever been used? This was used in Vietnam and is believed to have caused the downing of at least one F-111. The wires were strung across a valley that was a often used route. I believe they had other wires hanging from the main cross wires. Another simple counter measure that was used was to fire chaff up in front of the aircraft. The terrain following radar would see an obstruction and point the aircraft up giving a good IR target right up the tailpipe. The Army was conducting tests at NASA Langley to develop cable resistant helicopters back in 1983-85. They hung the Helo from the old Lunar Lander frame and swung it down into the wires. ( same method that was used to test some small planes for crashability.) I left the Air Force and the area in 85 and didn't here any more about the program. Bob Smart (bsmart@verdix.com)
sampson@killer.Dallas.TX.US (Steve Sampson) (04/11/89)
From: sampson@killer.Dallas.TX.US (Steve Sampson) In article <5516@cbnews.ATT.COM>, vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET (Bob Smart) writes: > > > From: vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET (Bob Smart) > > This was used in Vietnam and is believed to have caused the downing of > at least one F-111. My brother was a crew chief on F-111s at Mt Home and Tahkli (sp?) and the biggest problem was pilots flying them into the ground. He lost three in his enlistment. One in Vietnam was found impacted on a mountain ledge, said it missed the top by about 100 feet. Two in Mt Home were lost on the range but the pilots ejected, one capsules bladder never inflated and broke their backs. All in all he liked it better than the F-4 for maintenance, said he felt bad when the aircraft recovered and his didn't come back.
henry@zoo.toronto.edu (Henry Spencer) (04/11/89)
From: henry@zoo.toronto.edu (Henry Spencer) >Helicopters flying nap-of-the-earth (NOE) have been downed by striking >power lines and other high wires. It seems logical that one might >deliberately string wires across passes, saddles, or even between tall >trees as a means of defense or interdiction against NOE air operations. >Does anybody know whether such measures would be effective and whether >they have ever been used? Unless you count barrage balloons, I don't think there's a historical example yet. However, this is probably a valuable tactic, not so much because it would bring down lots of helicopters as because it would make the helicopter pilots more cautious and hence less effective. There is considerable work being done on equipping helicopters with some sort of short-range radar or lidar that can "see" wires, and a good many existing military helicopters are equipped with gadgets designed to cut any wires they strike, but the problem is by no means solved yet. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu
howard@cos.com (Howard C. Berkowitz) (04/12/89)
From: howard@cos.com (Howard C. Berkowitz) In article <5480@cbnews.ATT.COM>, mcgrath@nprdc.navy.mil (James McGrath) writes: > It seems logical that one might > deliberately string wires across passes, saddles, or even between tall > trees as a means of defense or interdiction against NOE air operations. > Does anybody know whether such measures would be effective and whether > they have ever been used? I vaguely remember an Aviation Leak article dealing with a possible Soviet defense against cruise missiles targeted against ICBM silos. Apparently, the strategic-range cruise missile of the time did not have the energy to do a terminal pop-up maneuver and dive, from height, into the target. There were reports of fencing or wires being set up at an approximate cruise missile altitude. This defense could be circumvented by a missile that rose several hundred to a thousand feet before entering the final target area. -- howard@cos.com OR {uunet, decuac, sun!sundc, hadron, hqda-ai}!cos!howard (703) 883-2812 [W] (703) 998-5017 [H] DISCLAIMER: Opinions expressed are not necessarily those of the Corporation for Open Systems, its members, or any standards body.
cantrell@Alliant.COM (Paul Cantrell) (04/15/89)
From: cantrell@Alliant.COM (Paul Cantrell) In article <5546@cbnews.ATT.COM> henry@zoo.toronto.edu (Henry Spencer) writes: >There is considerable work being done on equipping helicopters with some >sort of short-range radar or lidar that can "see" wires, and a good many >existing military helicopters are equipped with gadgets designed to cut >any wires they strike, but the problem is by no means solved yet. There are two current methods to deal with protecting helicopters from wire strikes. Both were recently described in either Defense Helicopter World, or possibly Rotor & Wing. The first method is detection. This article cast some doubt on the viability of the millimeter wave radar units for detecting wires, but did say that a particular laser system was looking possible. The second method is widely used today, in both civilian and military helicopters. The WSPS (Wire Strike Protection System) consists of an upper and lower wire cutter, and guides on the windshield and skids to deflect the wire into the cutters. A typical installation costs in the neighborhood of $35,000. The article claimed that the majority of single wire strikes WITHOUT the WSPS resulting in non-fatal crashes, while multiple wire strikes even WITH the WSPS typically were fatal. Therefore, the major effect of having the WSPS installed seemed to be to reduce the amount of damage to the helicopter, and therefore the cost of the crash, but not the number of fatalities. As someone who came within about 2 feet of a wire, and having a friend who crashed a helicopter after a wire strike, I hope an effective technology is found for this problem. For the helicopter I fly, it is the leading cause of accident today. PC Comm/CFI Helicopter
budden@manta.nosc.mil (Rex A. Buddenberg) (04/17/89)
From: budden@manta.nosc.mil (Rex A. Buddenberg) In the Coast Guard, we occasionally have gotten the hoist cable wrapped into the rotor blades, usually on night training exercises with motor lifeboats. Scares the ____ out of the flight crew. And usually the lifeboat crew too, but that's a delayed reaction 'cause they don't know how close they came until after they get back to port. The scenario usually involves a hoist cable getting hung on something solid -- like a 13 ton motor lifeboat -- at low altitude. Then a <sproing!> and enough backsnap to flip cable into the rotor blades. Hoists have a guillotine knife for shearing the cable in such situations, and it's a mite disconcerting taking that whirring back to a landing somewhere. Not sure whether we've lost helos doing this, but I know we've had some damaged blades. Customs also had one of their aerostats (balloons with a radar on a string) cut loose a couple years ago. Nobody sure, but the FAA records indicate that one of our H-3s was the only thing in the area and the coincidence points to it flying thru the fiber optic umbilical. Yes, barrage balloons may be an old idea, but I'd estimate that they could still be pretty effective in situations -- power lines get Army birds all the time. Rex Buddenberg -------
dee@linus.UUCP (David E. Emery) (04/18/89)
From: dee@linus.UUCP (David E. Emery) >From: budden@manta.nosc.mil (Rex A. Buddenberg) >power lines get Army birds all the time. The Army got smart and put "knife blades" on the Bird to help prevent this kind of thing. I understand they're pretty effective. However, that just requires a stronger cable... dave emery p.s. here's a picture... ---------- | the knives ---> \/------------\ | / | \/ | ---- |---------------------/\ | | | |--> /\------------------|