UL-1 Repair and Modification

[CraigP]

Yeah, a helicopter foil isn’t nearly enough lift. They spin very fast, and if you had a foil on there like the type of wing I made, it would go crazy! If you look at some pictures of an old DC-3 airplane, you will get a much better idea of the right wing profile. Also, the wing needs to be mounted so the leading edge is just below the opening to the air tunnel. It also needs to be angled up about 3 degrees. The wing is 1.3” wide. The trailing edge will end up above the airtrap, where air will get directed over the top of the boat. If your in to it, I posted on the steps of making a wing. I’ll try to find that and post the name of it here.

A reverse lift wing HAS to work, just like an airplane lifts into the air. If it doesn’t, then it’s made or positioned incorrectly.

[CraigP]

Here’s some pics I have of the wing construction I used on my Cat, which really worked well. This first pic shows the raw piece of wood, made up of laminating lengths of 1/4 X 1/4” basswood strips together. I used Locktite Marine 2-part epoxy as the glue.

[CraigP]

Next, I form the leading edge, important to round more on the lift side. You can see the radius is asymmetrical. Most wings that are ineffective are because of not making this leading edge correctly.

[CraigP]

In these two pics, the one showing the lift side up is complete except the trailing edge hasn’t been finished. The pic with the lift side down shows it complete...

[CraigP]

The basswood is a light, soft wood. It needs to be covered in a thin, fiberglass skin. These pics show the fixture I made to hold it and the glassing process. It takes about 3 coats of resin over the glass cloth to get a good buildup.

[CraigP]

Finally, finish sanded and being weighted. 17g, not bad, eh?

[CraigP]

Here it is rough mounted on the Skater 32 Cat. The wing positioning is almost identical to a hydro, you have an air trap, and you want to control the amount of air flowing under and over the top. Look closely at these pics and imagine the bow raising 3-4 degrees while running and see as the bow lifts, more of the bottom of the wing (lift side) comes into play. It starts to produce a laminar air flow over and under the wing and that’s when it’s acting the most as a wing. You can see by these pics it’s a fat wing, with lots of area difference above and below. It’s a DC-3 wing!

I hope that helps you. I’ve had the wing not mounted correctly and my DF34 hydro ran very wet! I won’t go thru the design analysis, but this will produce 3.5-4 pounds of downforce. That force has to start acting early or too much pressure will build under the boat and swamp out the negative lift, and the boat will blow over.

[InspGadgt]

True the wing cord on the heli blade isn't thick enough for enough downforce. Angling it will help but even flat it will provide some downforce...just not enough to make a difference. When I add a spoiler to it that will have the same effect. I thought about mounting it lower as you mention but I was just doing a temporary mount to test if it was going to have any effect. Once I finish testing it, if I decide to permanently mount it, I will lower it.