"In my opinion, the LINKNIFE is exceptionally brilliant! It is the best release I know about."

Donnell Hewett,
Towing pioneer, author of Skyting Criteria, inventor of the concept of towline tension sensing and designer of the Hewett Center-of-Mass bridle.

"NOTHING works better than the Linknife."

Jeff Sinason
Former Region 6 Director

The light weight, low cost, sure fire, place anywhere,
Tow Release for Hang Gliders and Paragliders

Your tow release MUST work
every single time.

Cut the weaklink and you're off the towline. It's that simple. No looped rings or strings to hang up. No draggy cable hanging out in the breeze. And best of all, no surprises.

Click here to see an animation of how it works (opens a new page)

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The Linknife works by cutting the weaklink.

Two stainless steel blades form a "V" which quickly and cleanly cut most anything that fits into the 3/16" slots, including perlon, towline, webbing and of course string weaklinks of any strength.

March 18, 2006 - At the Fall USHGA BOD Meeting, the Linknife received the National Aeronautic Association Safety Award. What an incredible honor!

What's so special about the Linknife?

Tow force passes through it, not into it. The amount of pull to activate is always the same. No matter how much force is on the towline, it always takes 4-5 pounds of pull to cut the weaklink. With all other bridles, the more tow force there is, the more strength needed to pull the release cord.
Light weight - At a mere 1/4 ounce, there's not a lot of mass that could cause problems to the pilot in case of a snap-back due to a towline break.
Small size - The Linknife is 2.5" long. This is quite a bit smaller than all other releases, so stowing it or placing it in optional positions is easy.
No towline hardware - Less chance of injury to people and things on the ground, including the driver who reels in the line, and greatly reduced chance of snagging a line during retrieval.
Designed for safety - From the small slots that prevent fingers from getting cut to the easily replaced O-ring, everything about the Linknife is about safety. It's up to you to use it properly, of course.
Flexible placement - Whatever style of towing you do, there's a place for the Linknife – on the glider, on the pilot, at the tow vehicle – for safety and reliability. It can also accommodate tubular webbing, perlon, towline... whatever will fit in the slots.
Works at any angle - Easily rotates around the weaklink to align with any pull direction. The round shape is nearly unaffected by the wind and won't rotate on its own.

Low cost - At $20 each in the USA (plus $5 shipping) the Linknife is the least expensive, most trustworthy release available anywhere.

A 1/4" (6mm) thick steel ring or rapid link - as shown in the photo above - backs up the Linknife in Static Line Towing or setups where the Linknife requires an angular pull... smaller links can get caught in the slots. In this manner, the rapid link prevents the Linknife from cutting the bridle. For Aerotowing, where an optional main release position is at the keel, the rapid link may not be necessary as the direction of pull to activate is nearly perpendicular to the bridle.

No matter what type of towing you are doing – Aero, Payout, Static Line, foot, dolly or platform launched – there is a place for the Linknife. It cannot accidentally come off, so it's always there when you need it.

NASA purchased Linknifes for use on the X-38 Space Station Lifeboat, using four on each craft to cut away the chutes if there's a problem. The head engineer was amazed that the Linknife weighs a mere 1/4 ounce and has no moving parts except for the sliding O-ring. It was also used to cut away the parachute on landing in Project Stardust.

Linknife Tow Release photo

COSTS:

Linknife — $20 each + shipping.
Club/dealer discounts available.

Bridles (aero or static), including Linknife,
rapid links and setup instructions — $50 each

ORDERING:

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US orders (Linknife single-order only)

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Other than US orders (Linknife only) drop me an email with your specifics for quantity and shipping method desired.

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Quantity orders of 10 or more Linknifes @ $15.00 each (add $10 shipping/insurance to US addresses for each 10 ordered)

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Bridles are made from red 900-pound heat set and stretched braided dacron with woven and hand-sewn loops in the ends. Kits include: Linknife release with extra O-ring, main 1:1 or 2:1 bridle, waist or shoulder bridle and connecting rapid links. Kits do not include the static tow waist bridle release mechanism (such as sailboat shackle) or release pull string as there are too many optional ways of setting this up. Custom bridles are available; please call or write with your specifications.

Static Line Tow Bridle (Hewett Center of Mass 2:1), or V-line (1:1 keel-to-pilot) Aerotow Bridle @ $50 each (plus $5.00 for ship/pkg) to US addresses. (Please add a note specifying which bridle you are ordering.)

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or send check to:
Birren Design Company
502 Shadywood Lane
Elk Grove, Illinois 60007
P: 847/640-0171
F: 847/640-0208
E: Email

DISCLAIMER: As with all aviation endeavors, your choice and use of equipment is totally up to you. It is assumed you are an experienced HG or PG tow pilot who is intimately familiar with the style of towing you will be doing. As such, YOU ASSUME ALL RISK AND LIABILITY in the use of the Linknife, as well as all other parts, functions and personnel involved in the towing and flight operations. If you do not have experience in towing, please contact an instructor for expert training. Trying to learn on your own can, and probably will, result in your injury and even death. Many pilots have paid the ultimate price so we may now tow as safely as never before possible. Please learn from their lessons.

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Your tow release MUST work every single time.

Your tow release MUST work
every single time.