FoamFloats.com submission for the SIG LT40

Submitted by: Dan Hayward

1: How did you cover your floats? I used Packing tape over 3M #77 Spray adhesive.

2: What is the distance of the hardpoints from the float tip (for both fore/aft hardopint)? The forward mount is 9.75 inches back from the tip of the float and the rear mount is 22.5 inches from the tip.

3: How did you mount the rear strut? I used the LT40's existing main gear and attached the floats with the nylon landing gear straps supplied and 2 wheel collars on each side.

4. Where do you like the step to sit in relation to the CG? I have the step exactly 1 inch behind the CG.

5. How is the take-off, taxi, and landing performance? Ground handling and takeoff from snow is very straightforward. I increased my rudder throws after an initial test in some deep powder showed that I had not very much directional control. Seems to work fine now but I haven't been in any deep powder again.

6. How does flight performance compare with no floats on? I'm still learning to fly so I may not be a good judge of any small influences the floats have on my plane's flight characteristics but I can say that they don't have any really adverse effect. The plane flys quite well with the floats on and there doesn't seem to be much drag from them.

7. What is the AUW of the float set? Mine came in at exactly 1 lb. including the wire nose mount/crosspiece.

After spending this summer building my first plane (a Sig Kadet LT-40) and learning to fly it, I decided to listen to my fellow club members and put it on floats and fly off the snow this winter. I had thought about making a set of my own floats from some foam but then I came across a link to foamfloats.com. I could either spend hours driving around looking for foam and then hacking away at it until I got a crude float or I could just order a set of these beauties. I¹m pretty sure I made the right choice!

When they arrived, I found everything I needed to get them on the plane. I first laid everything out to get an idea how I¹d go about mounting the floats. The easiest way looked to be using the existing main gear as is and fabricating a front mount from the supplied wire that would utilize the nose gear mount already on the plane. The only modification to the plane itself will be the removal of the main wheels and the nose wheel and strut.

My next decision was what to cover the floats with. I toyed with the idea of using an iron on film or fiberglassing them but I had read that many people have success with plain old packing tape. I figured I¹d try that method first since it was the cheapest and easiest way to go. If it didn¹t work out, I could always peel it off and use one of the other methods.

So, once those decisions were made, I epoxied the front and rear halves of the floats together, being careful to make sure the channels in the tops were aligned for the full-length 3/4² x 1/4² wood strips which would be epoxied in later. You could epoxy them in at this stage, but I waited until after I had applied the packing tape because I wanted to fold it over into the channels and trap in in there with the wood strip. This really worked well and makes for a really neat look to the tops of the floats. I won¹t have to worry about the edges of the tape coming loose in that area.

After the two ends of the floats were firmly together, I sanded the floats lightly to provide a smooth surface for the tape. I planned to use 2² wide clear packing tape for the tops and sides of the floats and 2² strapping tape on the bottoms. I used 3M brand tapes. The instructions suggested spraying the float bottoms with 3M 77 spray adhesive so that¹s what I did. I also sprayed it on the tops of the floats after the bottom tape had been applied, just to make sure the tape adhered well to those areas too. That¹s another reason to add the wood strip after the tape, if you had put it on first, it would be covered in spray adhesive now.

Taping wasn¹t too hard, you just have to be careful to get it where you want it the first time so that it doesn¹t go on wrinkled. The spray adhesive really grabs the tape and repositioning it is almost impossible.

I sprayed my floats with one light coat of Krylon primer and then a coat of silver Rustoleum. I¹m not sure if this is fuel-proof though.

All that¹s left now is mounting the floats to the plane. I figured I¹d start with the step positioned 1² behind the CG so it was a simple matter of setting the plane on the floats in the right position and attaching the main gear directly to the wood strip with a couple of 5/32² landing gear straps. I used a wheel collar on each side of the wood strips to hold the floats on laterally. You will need to fabricate a forward mount to connect the floats to the nose gear block which is already screwed to the firewall. I used the 1/8² steel rod which came with the floats for this purpose. The first step was to cut a length to the same width as the main gear, this will form the forward cross piece. From the leftover wire, I cut a piece which will have one end bent 90 degrees to solder to the center of the main cross piece. I then cut the remaining length of wire in half to use as the diagonal braces, bending the ends to lay flat on the vertical and horizontal pieces. I soldered the center piece first and then added the diagonals. I¹m not a wiz at soldering but this didn¹t turn out to be as difficult as I thought it would be.

I now inserted my front mount into the nose gear block and secured it with a wheel collar in the opening where the steering arm would normally go. I then secured the ends of the cross piece to the tops of the floats the same way the main gear mounts were done; gear straps and wheel collars.

That¹s it! I might tinker around with the fore and aft position of my floats because my plane sits a little tail down on the floor. However, my plane¹s CG did not change at all, it is still where it¹s supposed to be. I think the plane will nose down a little when it is sitting on snow and power is applied, so a slight rearward tilt is probably OK for now. I hope it snows soon so I can get out and do some flying!