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View Full Version : UL-1's Sponson AOA (4 degrees)



detox
06-02-2009, 09:37 PM
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
06-02-2009, 10:14 PM
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. :thumbup1:

detox
06-02-2009, 10:51 PM
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
06-02-2009, 11:13 PM
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
06-03-2009, 12:43 PM
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
06-03-2009, 01:20 PM
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
06-04-2009, 07:59 AM
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. :confused2:

Rex R
06-04-2009, 12:57 PM
decreasing the AoA should also reduce the aero-lift from the sponson.

detox
06-04-2009, 02:52 PM
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
06-05-2009, 01:02 AM
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
06-05-2009, 03:43 PM
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. :smile:

line6
06-05-2009, 03:55 PM
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. :smile:

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
06-05-2009, 03:58 PM
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. :smile:

detox
06-05-2009, 04:44 PM
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/wti0001p?&I=LXK204&P=ML


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CircusCircus
06-06-2009, 09:16 AM
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
06-06-2009, 06:59 PM
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
06-06-2009, 08:11 PM
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:doh: 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 :huh:

detox
06-06-2009, 10:16 PM
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
06-07-2009, 01:56 PM
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
06-07-2009, 07:32 PM
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. :smile: When a LSH Spec race comes up, I'll build a PT SS 20, period.

detox
06-07-2009, 09:22 PM
Have you tried the Grimracer L40 x 57/3 prop? It's 3 blades should chine walk less.

properchopper
06-07-2009, 09:25 PM
That was my exact thinking. Cavitation city. It worked with the UL-1 motor a little better.

detox
06-08-2009, 03:39 AM
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
06-08-2009, 10:51 AM
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.


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Brushless55
06-08-2009, 05:54 PM
Sounds like this cool mod is working..

detox
06-08-2009, 06:09 PM
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
06-16-2009, 05:33 PM
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
06-17-2009, 04:13 PM
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
06-17-2009, 04:33 PM
Looks good man, keeps us posted on how she runs..

longballlumber
06-17-2009, 04:58 PM
Nice work on the sponson mod!!!

properchopper
06-17-2009, 05:05 PM
Keith, I applaud your efforts to get the UL-1 performing correctly. Modding RTR's are a valuable learning tool, and I'm sure many of us will profit from your work. I've got mine running acceptably with the SV-27 motor & the G-10 pads & splayed packs. I was one of the first people to get one, and the first [ to my knowledge] to experience & report the fin problem & subsequent fix. But I'm moving on, now that the UL-1 has whetted my appetite for hydros. Witness my next project, a
30"nitro that's been gutted & ready for the install of 1515 1Y power. :rockon2:

detox
06-17-2009, 05:06 PM
With strut bottom set 1 5/16" below transom AOA is slightly under 2 degrees.

detox
06-17-2009, 05:13 PM
Witness my next project, a
30"nitro that's been gutted & ready for the install of 1515 1Y power. :rockon2:

Thanks, FYI I have a Phil Thomas SS21 hull on order:rockon2: I hope it meets my expectations.


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properchopper
06-17-2009, 05:22 PM
I was a day away from ordering a PT myself when this deal came along [ Mr. Pachmeyer gutted the interior & CF'd the inside.] For 110 bucks I had to jump on it ! I'm sure , with your obvious skills the PT's gonna' rock. :rockon2:

detox
06-17-2009, 05:26 PM
Propperchopper, What is the AOA of your new hull? I bet it's less that 4 degrees. Maybe you can post a side shot of hull resting on setup board?


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properchopper
06-17-2009, 05:51 PM
There's no strut as yet, so I can't really tell, BUT eyeballing it I'll say It's WAY less than 4 degrees. There's also considerable dihedral which predicts some decent cornering. I'll have to work the sponson bottoms some to get them " blueprinted".
Unfortunately I'm in the middle of moving so I really can't start for at least 2 weeks, + my 2 1515 1Y's are at Nue for some "refreshing" :crying:

detox
06-20-2009, 10:45 PM
I applied Krylon White primer then sanded. I will apply White Krylon finish coat to sponson area only.

detox
06-21-2009, 12:08 PM
Letting White Krylon bake in the sun. I will try to get video this evening.

properchopper
06-21-2009, 01:31 PM
Keith, for what it's worth, I just spent a full day at the NAMBA Dist. 19 time trials with some of the fastest rigger pilots there are, and I gleaned that sponson angle is ALL important. Good luck with your mods Bro, looks like you're on the right track, and do post the results :thumbup1:

detox
06-21-2009, 09:39 PM
Sorry... no video. Low reservoir level, windy conditions, and weeds prevented a good test, but I could tell that the hull is more stable than before. I will try again soon.


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Drag Boat Bob
06-21-2009, 10:37 PM
Sorry... no video. Low reservoir level, windy conditions, and weeds prevented a good test, but I could tell that the hull is more stable than before. I will try again soon.


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I agree with PropChop,
I just ordered one of these (pic). I guess I am just not the drive that I thought I could be. I will still play with the UL-1 to have fun, but as PC said; it is limited. I am not sure just which motor I will put in it just yet (learning), but as an old 1320' guy, this may be my boat.

Bottom line here is... look at the sponson AOA' kinda looks like where you are headed.

Good luck my friend...

properchopper
06-22-2009, 10:11 AM
Bob, that boat is GORGEOUS ! Gotta' hear more about it when you start your build.

LuckyDuc
06-22-2009, 11:32 AM
Fancy looking rig Bob. What are the details?

Drag Boat Bob
06-22-2009, 01:37 PM
It is a rigger design that can be set up for circle or SAW, but you most likely knew that.

I have a very good friend who is visiting family and friends in Germany. He is not far from Kelheim where these are made. He said he will see if he can pick one up while there and ship it to me.

If this fails, I will be destined to order one from the US which most likely will take much longer.

I am hoping to get a lot of advice on the build and take my time. Being new at this, I don't want to screw it up.

In the meantime, I am still playing with the UL-1.

screamin
06-01-2011, 12:04 PM
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. :smile:

Hi,

I was considering spreading my batteries out as well.
Can you tell me how you hold them in place & if there is sprayed foam in the sponsons to stop them from moving around.
At this moment my UL1 runs with the left sponson completley out of the water so i want to settle it down.

Thanks

JR