rhall999

Had some fun last weekend with some gliders and a Kadet Seniorita this past weekend. It was Thanksgiving weekend here in Canada, so all of my wife's family was up for a visit....but, both my father-in-law and brother-in-law fly so we went to the field

Here is the towplane specs:

Sig Kadet Seniorita
Saito .30 with APC 12X4
Mods include ailerons, taildragger, drooped STOL wingtips.

The 2 gliders we were towing were:

#1-Great Planes Spirit, built stock as per the plans.
#2-Scratch built Saggita 900, increased span to 111", spoilers replaced with flaps, airfoil changed to a Selig 3021.

Our setup is pretty simple, the towplane has a bolt on wing so we simply tie some kite string to an automotive ring terminal and put it under the wing bolt. (It is single wing bolt in the center). We have no release on the towplane except the throttle....I will explain below

The gliders simply have a short piece of music wire bent in an "L" coming out the bottom of the nose. The glider end of the towline simply uses a key ring to attach to the glider, with a streamer tied to the string about 2" ahead of the ring.

The way this simple setup works is that the line tension is what holds the glider on. If the line goes slack, the streamer falls down and backwards, pulling the ring off the glider towhook. It is quite foolproof really. When you are ready to release, or have a situation which calls for an abort, the tow pilot simply throttles back to idle, and the glider "dips" very slightly to gain speed and make the line go slack, and you are released!! The Sagitta was even better, I flew the tow with the flaps down about 10°, and when we were ready to release, the tow pilot throttled back and I put the flaps up, and the glider gained enough speed on its own to release nearly instantly. It was pretty neat to watch.

In the nearly 20 tows we did on the weekend we only had one issue, and that was caused by my brother-in-law diving the glider too much. He released fine, but then dove back into the towline and got it wrapped around the wing of the Spirit!!! But, since we use thin kite string, one good jerk from me on the towplane and break the string, both planes land safely for another go.

Pictures to follow..........

rhall999

Here are some pictures. Not the greatest as it was pretty early in the morning for a few (before the wind came up).

da Rock

A number of clever details there.

The release is a great idea.

rhall999

Thanks!! We learned through experience that the streamer on the line is a must. The first couple times we towed this way we just had the key ring on the glider end, and sometimes releasing wasnot what you would call "reliable" We found that simply tying the streamer to the key ring can also cause "binding", so we started to put it slightly forward on the string and it has worked flawlessly so far. Plus, there is a visible cue as to whether or not the line released. Also helps the tow pilot see the end of the line when landing so he does not snag it on the barb wire fence along the runway. (That, by the way is hilarious to watch!!!)

Another towhook idea that my father-in-law likes to use is really simple. You know those "teacup hooks" that your wife likes to screw into the wall or cupboard and hang decorative teacups on.....well, he has a couple gliders that he simply screwed one of those into the nose block and bent the "outlet" straight, and away we went. 2 bucks for a pack of 4 towhooks at the hardware store!!!