Protech Ibis 120 - How to properly attach the tow hook release.

[Charlesd]

Hi,
I know a few of you are using the Protech Ibis 120 as a tow plane. The Protech is the same model sold by BP Hobbies and Texas RC.

I'm presently building mine and realized that there is not much meat behind the wing attachement plate to bolt in the release. Can you guys post pictures or indicate what you did to modify the plane for the release?

thanks
Charles

[Len]

Hi Charles, You can install some additional light ply to thicken the top skin behind the wing and add a short former and bracing. We have all discovered the tow release on the plane needs to be sturdy, but not overbuilt. You're not pulling against a non movable object, so just a good solit installation is adequate.

Here are a couple links off the website that have losts of pictures of different setups. I'm sure you will find something that may be helpful. If not, please post some specific pictures of your plane and I'm sure we can all chime in with suggestions.

LEN

http://www.rcaerotowing.com/1558-tow-releases.html

http://www.rcaerotowing.com/1540-fab...mechanism.html

[RKM]

I added a piece of maple, 3/4 x 1/2 and the width of the fuselage behind and at the top of the former (behind the wing bolts). I also changed out the 4 mm wing bolts for 1/4-20's, and beefed up the landing gear. No pics but I can get some tonight.
Ross

[Charlesd]

Hi,
Pictures would be great of what you did to yours.

I haven't removed all of the covering yet but will do so tonight when i get a minute. I see that there are 2 beams in the middle that will have to be sectioned and re-inforced. My release does not fit in between.

plane needs to be sturdy, but not overbuilt

Len - would railroad ties welded in as bolts be overkill?

[Len]

lol, just a touch.

[RKM]

The tow release is home made and the maple beam is on the back side of that former. I have had a few rough tows and am surprised it has held up, have towed an 8lb plane so far. I also added the tail bracing and landing gear bracing. I don't use the kit supplied wing struts. Also notice the 1/4-20 wing bolts. I'm planning to swap 4" wheels on it soon.

[Charlesd]

Hi,
Now i see what you mean. I also have the tail brace kit but did not think of making a landing gear brace. It's a very good idea as Gerben (Ibis owner in Denmark) broke his gear after a few rough landings. He now has a carbon fiber gear.

I was planning on installing my release aft of the trailing edge and not touch the wings. The hook would go between the 2 rails. I would have to remove a bit of wood on the inside and i would strengthen the rails on the outside. I would bolt the release on a plate much like the link the Hangar 9 cub that Len put in his post.

Would this be to far in the rear of the plane?

[RKM]

I did have to put a small notch at the trailing edge of the wing, but don't think it's a big deal. I knocked my gear off on the third landing when I came up a little short of the runway. I didn't think it was a very hard hit but it ripped the ply mount out of the plane. Typical arf problem, sparce glue joints. This plane really comes down quick when you chop the throttle I don't even use flaps on landing. I'm also going to install a more robust tail wheel assembly the stock one is kind of flimsy.
Either behind or in front of that bulkhead should work just fine. I don't have any complaints about how my release works or how the plane tows, but this is my first experience towing so I have nothing to compare it to.

[Charlesd]

I've been putting Triangle re-enforcements everywhere. Landing gear plate, engine mount plate, etc... I've put 30 minute epoxy in every corner. I also plan on installing my 5 inch dubro inflatable wheels. It should absorb a bit.
I test fitted the motor. With a 20*12 Prop on 12s, this should pull over 2400 watts. I also put a patch of black for visibility.

[RKM]

The bare airframe is pretty light, I don't mind adding stuff to beef it up, it's overpowered with the DLE 20. I used 3m contact cement to attach the side windows, came out nice and way easier than trying to drip CA in there and having it run down the window. After you screw on the front wind screen take a heat gun and form a corner on each side kind of like an "A" pillar on a car, takes some of the stress out of it and the screws hold better. It doesn't take much heat though. Also, this is the only plane I have ever had that required rudder and aileron mix for coordinated turns.