I made this in a few hours, out of stuff I had in the shop, and based it from a internet pic of an old Schweizer release. Those are no longer made, and I couldn't find a used one, and the German made Tosts (now common in sailplane towing, the Schweizer's are very old hat) are priced sky high. I was quoted $2800.00 for a complete kit!

This cost me a big fat zero. I made it full scale, based on the pic I printed out, having no idea if that was a full scale pic or not, it looks about right anyway, as you can see. My needs will put quite a bit less stress on it then towing sailplanes, so I re-engineered it downwards/made it lighter and wimpier. I will use it as I push my plane out the hangar, on it's wheels, and then transition to the skis, right at the last bit of level area outside my hangar, from there it's 14% down all the way. With this release, if I change my mind and decide I really don't want to go ski flying, I'll be able to abort. The way I've been doing it, once transitioned to the skis ( about 30 seconds to deploy them, engine off usually) and then once restarted, I'm going flying as soon as I restart, like it or not.

I have yet to figure out how to install it, my last thought today while still in the shop was: rather then screw with figuring out a mount on the plane, which would get complicated quick, I may just use the HydroSwing door lower truss as a hard point to rig to. I'd leave the entire release on the ground in other words, using it backwards in effect. This will require me to leave one door open to pull the release line, and a pully to release the direction of travel, I'll figure something out...even if it means I fly off with 20' of rope trailing behind me, it will still be simpler and lighter then installing the entire contraption onboard. My primary/only use of this will be at my home strip, In the past I have had a few times where I could have used a tail release while landing out somewhere, but I have ski flying all figured out now and those times are past

Here is the mount for a Schweizer hook on my Maule. If you need the drawings I should be able to help. If you made the hook you should be able to make the mount. Not sure if you’re experimental or have flat tailwheel leaf springs but it’s a simple attachment.

Yes, flat spring (J-3 type), and exp. Thanks for the pic, I will put that info into the mental mix of whatever design I dream up. I like the dual arms, hmmmm, got me thinking.

6" of snow last night, skis install for the season takes place today, always a bitter sweet thing. Taking off the 29" Airstreaks sucks, putting on the 6:00's in their place sucks more, but then when the wheel skis go on, all is good again! I will install the tail wheel ski first, as it will of course effect the entire tail release project.
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Since it's not clear in the picture and I can't take another one right now I'll describe how it attaches. There is a U shaped bracket that attaches under the forward leaf springs and main fuselage attach bolt. The tow hook arms each have a hole on the forward ends that bolts to the U bracket and acts as a pivot point when the leaf springs flex. There is another smaller gauge bracket that you can see that sits on top of the leaf springs and keeps the hook arms and U bracket from pivoting side to side.

And....finished! Thanks for the tip gdflys, your mention of the drag links (my term, sounds about right) having to be able to pivot made the entire thing crystalize, everything fell right into place and best of all I had everything needed already, even though I had to scab together both drag links out of several short lengths) 3 lbs 12 ozs. all up weight. My projected load on this "system" will be 10 to 100 lbs at most. So I engineered it accordingly (half ass). Just need paint and some nylon tubing to run the 1/16" stainless pull cable (I have a whole roll of the 1/16", left over from the ultralight days) through. No fairleads, the trigger forces should be low enough to be able to keep it real simple. I have a plastic buffer on the tail spring capture bracket, to allow for up and down movement, and side shims to keep it solid side to side. The drag links work off the main tail spring bolt of course, I just had to turn it around, nut down. Once operational, it should just take about 20-30 minutes to re-install/take off. I just need paint and the tubing, out of pocket cost will be those two items, less then 20 bucks.

Looks like a factory install. Just make sure the release cable can't get fouled in the rudder if the tail springs are compressed. It looks like if you run it under the mid bracket then it should be fine. Nice work!

I may be the dummy here, but what is the purpose of a tow hook on a ski plane? Hand prop tie down anchor point maybe?

Man , That's top shelf, So is the ski !

jlacharite wrote:I may be the dummy here, but what is the purpose of a tow hook on a ski plane? Hand prop tie down anchor point maybe?

I have yet to figure out a way to put brakes on my skis! This will be a big help for the transition stage of not being all the way on the skis, but not quite on the wheels, it will allow me to re-start once on the skis, and just sit there idling, without starting down the slope. It can get complicated quick, trust me, and the release will be another tool in the winter time box.

Now I just need to figure out how to stuff 18' of 1/16" cable down a 17' length of 1/4" nylaflo tubing. It comes rolled up, like any poly piping, and just trying to push on the cable that distance won't work. I may have to suspend it vertically from the ceiling of my 14' shop, with the last 3' going down the stairs to the hangar. Put a little weight on the bottom of it, and wait a day or so until it's straight, or nearly so. Then tape the cable to a short length of welding rod, anything with a bit of weight, but that isn't too large to impede sliding down the tubing. The shop air compressor may come into play, and the 12' step ladder' Like I said ski flying gets complicated.

I was going to suggest air Tom. Attach the cable to a plug that fits in the hose and blow it through with a nozzle. Might be your best bet.

For anybody not quite as talented as courierguy; I've got a Schweizer hook on the shelf. Taken off my old-SC. Make me an offer. PM me.
Jack

NOW you tell me!

Probaby 15-20 hours of labor in my setup so far. The release went quicker then figuring out it's mount. Like any mod it always takes longer then you first think. Always!

I have the STC paperwork for the tow hook that was on my 172 when I bought the plane. Hole still in the tailcone from where it was mounted when I had the plane in for annual and painting! Didn't realize it was missing from the plane until I was 1,000 miles away from the shop that did the work. Of course they didn't have it or know anything about it.

gdflys wrote:Here is the mount for a Schweizer hook on my Maule. If you need the drawings I should be able to help. If you made the hook you should be able to make the mount. Not sure if you’re experimental or have flat tailwheel leaf springs but it’s a simple attachment.

If you have a drawing I’d be interested in it

"Now I just need to figure out how to stuff 18' of 1/16" cable down a 17' length of 1/4" nylaflo tubing."

Use a vacuum to draw a string into the tube and use the string to pull the cable.

Good idea, but to my surprise, the cable pushed into the entire length of the tubing easily. All I had to do was clamp either end to hold it straight, and make little pushes of a few inches at a time. This speaks well of the inner slickness of this black plastic tubing, usually used for small air lines in big rigs, shifters, PTO's etc. Also to my surprise, the routing of the cable/tubing, took only 3 minutes and 4 zip ties. I expected the usual many times longer then what I expected, taking it out in the spring will be equealy painless. I can't see any chance of it fouling anything, especially the the rudder control, that will be a good thing.

I made a test release and it worked as expected, all I have left is to rattle can paint it. Then I can test it for real, with a bit of a load on it, and make my first ski flight of the season, all at once.

I made my first ski flight of the season, with the new release, and with the new wazoo (as in very trick, so trick it seems like I'm flying a different plane, they make the ANR Telex (14 year old technology) they replaced seem like tin cans and some string) Lightspeed Zulu 3 headset. So, a lot going on, plus I hadn't flown at all, much less on skis, for almost two weeks. I feel the rust buildup just a tad after that long, that's one reason I like to fly a lot, and keep things lubed up.

It went well, one hand on the stick, one on the throttle, and one for pulling the release. As expected, it was less stressful, being able to re start, without immediately sliding down the slope, but rather being able to choose when I wanted to start the takeoff. The HydroSwing door truss could not be located in a better spot! I always did a run up before, while still on the wheels and the concrete, but once on the snow on the skis, that was the time when gravity was not my friend. So, a worthwhile project, for my particular set of circumstances anyway.

Pacific Aerial Tow Hooks sells an FAA PMAed tow hook and release lever with an STC. Its a lot more than the couple hundred bucks you spent, unless you count your labor at shop rates. For just ground work, I would have mounted it on your tailwheel either with a top bracket, or by making a new top spring with an extension on it.

It has worked perfect, and there is certainly no need for a "approved" part in my application! My total cost was about 20 bucks, and my time is worthless.

BUT, since I put a new tail spring on (T-3), and also noticed that when I took my tail ski off this spring it's mount showed obvious signs of needing further "engineering", this year's re-installation of the release will require some mods. Maybe another 5 or 10 dollars worth, we'll see. The release mechanism itself has proved to be easy to release under load, and also reliable (good thing), now to just figure out how to reattach it to the new hardware back there. I'll consider your suggestion when I do, thanks.