wire strikes

[marrty41]

I watched a jetranger land today and noticed a spike fixed both to the top and bottom of the front of the cockpit .My instructer informed me that they were for wire strikes and that they would cut the wire if flown into one.Is there a mechanism that cuts or is it just a sharp blade.Can they be fitted to any helicopter?

[67november]

the WSPS (wire strike protection system) is a type of blade system, they are designed to grab the wire before it reaches the rotor mast or skids, it will cut smaller diameter wires but it's more to protect the craft giving the pilot time to react.

[AIR9ENG]

Here are some helicopters equipped with wire strike kits:

 

http://www.crescentair.com/spares/wskits.htm

 

They are available for several models

[PhotoFlyer]

the WSPS (wire strike protection system) is a type of blade system, they are designed to grab the wire before it reaches the rotor mast or skids, it will cut smaller diameter wires but it's more to protect the craft giving the pilot time to react.

 

If it is a larger diameter wire, and it can't be cut, the helicopter would just pivot around the wire. How would that give the pilot time to react? Depending on which cutter it went into (upper or lower) the helicopter would rotate around the pivot point, either up or down. If it was going fast enough it could end up in a very severe (even upside down) attitude. Typically, those types of attitudes are bad for helicopters. Semi-rigid rotor systems in particular. Combine that with the fact that the heli is close to the ground, and I think you can imagine what the outcome would be. Unless the helicopter was flying slow enough that they just ran into the wire and it stopped the helicopter, I think the results would be similar to those if it wasn't equipped with a WSPS.

[dlo22]

How about powerline wires, high voltage, that are commonly strung from pole to pole, will some of the wire cutters, cut through these wires, say going about 40 knts.????

I know of two pilots that have hit these powerlines, flying out of really congested, wooded areas, one smashed the helicopter and one landed the heli perfect after hitting the wires... don't know if the wire cutters actually cut the wires or if they just bounced around the wires or what...

[Goldy]

How about powerline wires, high voltage, that are commonly strung from pole to pole, will some of the wire cutters, cut through these wires, say going about 40 knts.????

I know of two pilots that have hit these powerlines, flying out of really congested, wooded areas, one smashed the helicopter and one landed the heli perfect after hitting the wires... don't know if the wire cutters actually cut the wires or if they just bounced around the wires or what...

 

 

First off, these devices are a last hope...a last resort. You just flew into wires, oh crap !..The theory is the wire will travel up or down the bubble, entering a cutter with sufficient inertia to cut the wire. Most larger helo's, with forward airspeed, can accomplish this depending on the strength of the conductor it is cutting. You will rarely see strike kits on smaller birds, like an R22...it just doesnt have enough mass. There have been many instances where a helo has survived a wire strike due to the cutters....but that doesnt mean that having cutters will save your butt every time. If I had my choice, I would fly with wire strike kits all the time, it can't hurt.!

 

Now, if only they made fixed wing strike kits, that could tear the wings off an approaching plane canyon flying at 200 AGL !! Those I want !

[Scottie]

They do work sometimes but as someone else pointed out, they are a last resport and it all depends on the angle, weight and velocity of the aircraft. I have seen OH-58's dangling by powerlines and watched a Blackhawk fly around with about 1000ft of cable behind it.

 

It's kinda like washing your hands after you pee. Dont pee on your hands and you dont have to worry about it

[67november]

here's the test results from the DTIC

 

Title : Verification Testing of a UH-1 Wire Strike Protection System (WSPS),

 

Report Date : NOV 1982

 

Abstract : In-flight wire strikes poses a serious threat to low-level helicopter operations. Under the sponsorship of Headquarters, US Army Aviation Research and Development Command (AVARADCOM) tests were conducted by ATL to determine the suitability for UH-1H helicopter application of a Wire Strike Protection System (WSPS) manufactured by Bristol Aerospace Limited (BAL). The WSPS initially tested consisted of fuselage-mounted upper and lower cutters and a windshield centerpost deflector with a sawtooth cutter. Using the NASA-Langley Research Center's Impact Dynamics Research Facility, a UH-1H helicopter fitted with the WSPS was subjected to pendulum swing tests in which the helicopter struck strung wires at approximately 40 knots airspeed. The WSPS demonstrated its capability to sever an 11,500-pound tensile strength steel, seven-strand 3/8 guy wire. Also, a significant wire-cutting limitation peculiar to the UH-1H was identified. At wire impact 30 degrees from the normal to the flight path, it was demonstrated that the wire could be snagged by the windshield wiper shaft, preventing the wire from being deflected into the upper cutter. As a result, BAL and ATL analyzed the situation and both concluded that a simple windshield wiper shaft deflector could alleviate the problem. Windshield wiper shaft deflectors fabricated by BAL were installed on the test aircraft and additional swing tests were conducted. Successful deflection and wire cutting were demonstrated. Installation of the WSSPS,. as modified by this effort, on the Army's UH-1H helicopter fleet is recommended.