UL-1's Sponson AOA (4 degrees)

[detox]

With my strut and sponsons resting on LEVEL setup board the AOA (Angle Of Attack) of my UL- 1 sponsons measure 4 degrees. That is with strut lowered 1 3/16" below transon / hull floor. To adjust my sponson angle to a more WET 3 degree angle I will have to lower strut aditional 5/16" to setup board. I will try this lower strut setting (1 1/2") to see if it helps make my UL-1 more stable in race water. I will have to bend the brass stuffing tube to do this.

[properchopper]

I'd be interested to hear of your results. I've thought of adding another layer of
G-10 ridepad[s] at a shallower angle to get less AOA, also cutting out the inside of the forward tub area to get the batteries partially inside the sponsons to change the moment of torque, reducing the death dance. It'll get the CG forward some as well.
Keep us posted.

[detox]

Adding material to sponson ride pads will raise COG of hull. I think removing rear of ride pad then add fiberglass and G10 maybe. That way you would not have to raise strut any further . Notice red line in picture.

[properchopper]

I see your point, although I'm not sure raising the CG such a small amount would upset anything. Before I open up the tub, I plan to put my ballast taped to the top of the sponsons to see if the wider distribution of weight has a calming effect on the wobble. Once inside It'll have a lower roll center, however. We'll see.

[detox]

Here's more pictures to help decide how to close in AOA. Perhaps gluing a 1/4" door shim under each sponson would do the trick. Angle needs to be closed half way to be 2 degrees. Making a door shim should not be hard to do using bass wood and table saw.

[Hydromaniac]

You can get beveled fiberglass door shim material at Home Depot and Lowes. I have used it to make ride pads and also to change the AOA.

[Capt. Crash]

Someone please explain to me how that is going to affect the ride and help the hospital hop. The only part of the pad on the water is the very back, when on plane.

I'm thinking rounding off the rear outside edges of the sponsons might be worth a try. This might help with the boat being upset when crossing wakes.

[Rex R]

decreasing the AoA should also reduce the aero-lift from the sponson.

[detox]

Reducing sponson angle from four degrees to two degrees will help boat run wetter and be less bouncy, but causing more strain on motor/esc. I am not sure if the stock UL-1 "esc" can handle this extra strain, but my NUE 1515 1Y and Hydra 240 should be able to. I plan on trying different angle ride pads (removable). They will be temporarily attached using 3M contact spray adhessive.

Here's current setup using NUE 1515 1Y 2200kv, Hydra 120 (using the Castle BEC with no failure yet), and Grimracer L38 x 55 prop. UL-1 is a missle using this power combo, but very flighty when crossing wakes. Hopefully reducing sponson angle will help... Air Dam or Spoiler may also be needed.

[detox]

You can get beveled fiberglass door shim material at Home Depot and Lowes. I have used it to make ride pads and also to change the AOA.

I purchased the composit door shims, but their width is only 1 1/2"...the UL-1 ride pads are 1 7/8" wide. I will try using bass wood first. I will cut two pieces @ 2 degree angle then hand sand to desired shape. Afterwards I will seal using epoxy finishing resin then paint.

I made some fiberglass G10 plate by compressing epoxy and fiberglass cloth between MDF board (Saran wrap between boards and epoxy prevented epoxy from sticking to MDF. Saran wrap peeled easily from dried epoxy). Homemeade G10 is LOTS cheaper than original G10. It takes four layers of compressed heavy weave fiberglass (Walmart) and epoxy (finishing epoxy) to equal 1/16" thickess. I will try making the bass wood ridepads before trying the fiberglass.

[properchopper]

Anxious to hear your ridepad-mod results. I'm testing my theory that the wobble can be reduced by spreading the battery weight further outward to move the roll center outward & at the same time getting the CG a little forward, which I believe will keep the nose better planted. I hope youu don't mind me intruding on this AOA thread, but we're both striving to get similar results.

[line6]

Anxious to hear your ridepad-mod results. I'm testing my theory that the wobble can be reduced by spreading the battery weight further outward to move the roll center outward & at the same time getting the CG a little forward, which I believe will keep the nose better planted. I hope youu don't mind me intruding on this AOA thread, but we're both striving to get similar results.

Nice idea let us know how it goes. I might try this also as i already have the holes their from reinforcing the sponsons and the turn fin. all i would have to do is cut the bottom i little more to make it flush with the inside tub.

[properchopper]

Nice idea let us know how it goes. I might try this also as i already have the holes their from reinforcing the sponsons and the turn fin. all i would have to do is cut the bottom i little more to make it flush with the inside tub.

I'll know Sat or Sun, depending on the weather & report back.

[detox]

I hope your idea works. I once tried adding lead tape weights to the outside lower edge of each sponson (3oz. each side) . It did help some, but not enough.
http://www3.towerhobbies.com/cgi-bin...&I=LXK204&P=ML


...

[CircusCircus]

A member of our club has done this mod, and it works well, the boat doesnt sponson walk as bad and seems to be more stable in the turns. The only drawback is getting the boat on plane from a dead start, the added weight makes it nearly impossible with certain props.

[detox]

OK I decided to try the composit door shims. I measured for slight toe in (1/16" total)...then tacked them in place using 3M spray adhesive. If I am not happy I can allways remove them. I will test this evening.

[properchopper]

Ran today; the splaying outward of the batteries substantially reduced the chine dancing; probably @ 80 %. I also closely observed the hull under acceleration and noticed a pronounced lifting of the left sponson in rough water or wake crossing when the prop unloads and loads again, which will induce the dance for sure. I'll experiment with props to see what helps [ I usually run with a hub-cut X442 ; easy out of the hole & close to 50 mph]. Left the prop box home today so couldn't test any others. Wil run tomorrow with a SV 27 motor 'cause I need to borrow the UL-1 motor for my VS-1 which threw a magnet when I did a dumb thing today-don't ask

[detox]

OK here's my results. After sponson mod the UL-1 was only a little more stable. I will replace the door shims (2 1/2 - 3 degrees BTW) and try less angle (1 - 2 degrees) using the bass wood.

[detox]

The door shims removed fairly easily, I pryed up edge then peeled them off using a good bit of effort. The 3M spray tack residue was remove using acetone and paper towels. Once I receive my bass wood I will cut then try them.

[properchopper]

Here's what I found today, after yesterday's run with the "splayed battery" location which substantially reduced chine dance : I propped up to a M445 to compensate for the lower KV -SV27 motor [ I had to borrow the UL-1 motor for my VS-1]. With the bigger prop the chine dance returned big time, confirming my suspicion that prop torque can set up the conditions for the "dance". Frankly, I'm pretty much done with trying to dial in this boat. A youngster was there with a 1/12 Proboat hydro with an upgraded motor and it ran & cornered on RAILS. Detox, I wish you luck. For myself, I'm geting my hydro fix with my H&M 31" shovel which is running mid-sixties with LOTS more prop to go. When a LSH Spec race comes up, I'll build a PT SS 20, period.

[detox]

Have you tried the Grimracer L40 x 57/3 prop? It's 3 blades should chine walk less.

[properchopper]

That was my exact thinking. Cavitation city. It worked with the UL-1 motor a little better.

[detox]

OK I will try it again. I have a feeling it will work better this time. I placed shims on outward edges of sponsons and stopping at trailing edge (no overhang). This lowered ride height slightly...AOA is 2degrees now. Since my favorite Grimracer L40 x 57/3 prop is damaged I will have to use my second favorite for the next test...Octura m440. My Octura m440 is slightly faster than my GR L38 x 55.

[detox]

Boat did verywell this morning...sponson mod DOES work. Strut was also lowered deeper into water 1 1/4". Using the NUE 1515 1y power combo this boat hauls ace.


...

[Brushless55]

Sounds like this cool mod is working..

[detox]

Yea... UL-1 is handling wakes lots better.

Now I will have to adjust rudder a little more "fore" to settle down the stern hop in corners. Stock UL-1 came with too much "aft" or positive angle according to picture attached. I will have to file adjustment hole larger to achieve the required "fore"or "zero" angle.

[detox]

Been working on my new 2 degree ride pads. I cut these from a block of basswood. Hopefully after sanding and shaping they will look more streamlined...trailing edge will be much thinner than in picture. I may also cut some 3 degree pieces. I am not certin how I want to attach them.

[detox]

I ended up gluing ride pads on using Z POXY finishing epoxy. After epoxy set up I sanded pads down flat using a piece of flat 9" x 2" MDF board and sandpaper. I glued the 100grit paper on MDF board using 3M contacted spray adhesive. Next I will finish the ride pads using the Z POXY finishing resin then paint flat White..

[Brushless55]

Looks good man, keeps us posted on how she runs..

[longballlumber]

Nice work on the sponson mod!!!