arcdude

Your rig doesn't look all that different than Hooty if I've got the name correct and his was just fine with a ramp of about 4', there's only one way to find out

Jeremy_H

It looks great, one of those boats looks fast standing still .

To help launching, would it be possible to build in a couple of lift surfaces on the sponsons, that just clear the water when it's fully on the plane? I'm not sure if the air lift off them might become a problem in itself, dunno.

1QwkSport2.5r

Well, Hooty's boat is a bit heavier, longer, and has a Jett .90 with full tuned pipe. LOTS more power. He has to use a ramp with his rigger as it too barely floats. My biggest concern is if the TT .46 has enough thrust to keep it lifted enough once off the ramp to stay on plane. I have to make a few adjustments once I bind the receiver and run the engine on the boat to make sure it's going to draw fuel okay. I moved the fuel tank from the compartment in the hull to under the engine mount. This should help with the touchy needles along with using a bunch more nitro. I was using 5% nitro and I'm gonna go up to 15% which will give a bit more power.

1QwkSport2.5r

I have some flat pieces of liteply that I had used before as a "helper" for getting on plane and I'll have them with me when I get back to the pond for testing. I don't think the lift from the sponsons will be the problem. The problem will be keeping/getting the boom tubes out of the water. The surface tension of water is immense and being a cylindrical shape creates other forces that act against it. The trailing edge surface will be moving with essentially an eddy behind it which acts like glue preventing it from lifting further. So the biggest obstacle I face is getting the booms out of the water and keeping them out of the water. I do think the new sponsons will far and away work better than the old ones so if the engine has enough grunt, I think it will be capable of lifting itself up. I may need to move the engine to get the CG in a better spot. Right now the boat balances just aft of the backplate. That equates to about 7" behind the trailing edge of the sponsons and 5" behind the prop. The prop is about 1.5" aft of the trailing edge of the sponsons. I think the motor mount will need to be rebuilt completely to allow movement fore/aft to adjust the CG which I think can be the golden ticket to making it run out. I have more confidence in the hull now but not much. Testing will adjust my viewpoint on this.

Jeremy_H

Cool, I hear what you're saying.

Looking forward to the tests.

arcdude

You could always follow Jeremy's lead and plop a twin in that thing Lol, all you'd need is a couple of ailerons The 46 TT is a good engine and probably shouldn't be underestimated, you'll likely be o.k.

1QwkSport2.5r

Doubling the engines doubles the engine weight but the power required to move that weight needs to go up exponentially. Not to mention the complexity of plumbing a second fuel tank, throttle control, etc. The TT .46 is a good engine; I never said it wasn't. I just don't think it has the power to move this pig. For some perspective, the hull weighs over 6# RTR. The engine turning a 9x6 APC, 9x7 APC, and 10x6 APC respectively is 17,500, 16,400, and 15,700rpm. That equates to 1.5hp/5.80# thrust, 1.4hp/5.1#, and
1.67hp/7.1# The HP figure doesn't mean much but the thrust factor does. The less pitch, the more thrust but at the expense of speed. It's a BIG issue in an outrigger and really hydros in general as you need thrust to get it on plane and then speed to keep it there. Until I port the engine, it needs to be run in the 16,000rpm area for the pipe to be effective so going to bigger diameter props not only slows the rpm down, the engine has to be shimmer to clear them. I have room to run a 10" diameter prop but that's as far as I'm gong to go. Until I can test the new configuration, everything is speculation.

1QwkSport2.5r

There will be some videos on YouTube in the next few days that crispyspa was nice enough to take of this pig in action. Without a GPS but a keen sense of speed, he figured 50mph or thereabouts. It rips!

On a side note, his 25lb +/- 1/4 scale SI3 (the HUGE gasser model!!) on brushless power went 68mph on a 16x10 APC prop. Had a HOOT with the boats when the wind behaved.

arcdude

Congratulations, well earned I'm sure! Eager to see the video. What method was required to get the beasty going, ramp or a good chuck in the lake?

1QwkSport2.5r

Crispy launched it for me. The water would come over the boom tubes and up into the prop trying to plane off on its own.

1QwkSport2.5r

Video courtesy of crispyspa. http://youtu.be/rs_c9DJww0w

arcdude

Watched the video a couple of times, she's up and running, well done! The tubes really plow up the water, although it didn't seem to take much of a throw to get her going. The tail didn't seem to come up, at least the rear wing is adjustable and with it running you can now play with adjustments to increase performance. Nicely done

1QwkSport2.5r

We adjusted the wing and got it to run smoother than what's shown in the video. I have to make some modifications to the wing to solidify it and that will take care of the hop. The engine mount is going to go on a diet and get redesigned as well.

arcdude

Was the wing loose? Your engine mount looks pretty light from this side, how heavy is it? I'm kind of curious now how mine will work with the wedge sponson under the rear, if it goes lol, I can always put a bigger wing such as yours on the back and remove the sponson.

1QwkSport2.5r

The pivot point is just a metal rod going through a hole in the vertical stabilizer. It is a primitive hinge of sorts, and needs a more solid type of hinge mechanism. It has some movement that is allowing the wing to "flop around" so to speak when the boat is underway causing the back of the tub to bounce a bit. So I'll come up with a new pivot mechanism to reduce movement and retain the adjustability. The engine mount is made up of aluminum sheet and some heavy Brazilian Walnut hardwood. Originally the mount was one piece but I cut it apart to adjust the thrust angle in an attempt to get it to plane off with the old sponsons. There's extra screws and nuts holding it together that isn't needed if I make a new mount, I just didn't want to bother with it until I knew the boat would be successful with the new sponsons. Now that I know the new sponsons work as well as they do, I can rebuild the mount and get it back to a simpler setup. I have some good aluminum brazing rods and a good torch now so I can make the mount I intended for it to have in the first place. It should look much sleeker and be significantly lighter when I'm done which should help increase top speed. The goal is 70mph but I'll be happy with 60mph with the TT .46 engine. If all goes well, I'll get a Jett .56LX for it which will give up 2,000-3,000 more rpm than what the TT can do on the same prop (10x6 APC).

Jeremy_H

Sweet, nice to see it sat on top.

crispyspa

The tail just started to come up at 1:22 in the video. There is a slow mo section in the video and if you set your you tube speed to 1/4 play speed, you can really see it wanting to come up and stretch it's legs.

....And You didn't want to run it that day. Glad you did. I had fun too.

1QwkSport2.5r

I had my doubts as to its performance for one. And for two I figured it would have taken longer to set it up. Then again, in my haste I waterlogged it pretty good. I'm glad you talked me into it either way. A very fun experience. I'll hop it up a bit more for next time...

1QwkSport2.5r

Dusting this baby off... I made some new acrylic hatch covers, fixing the wobbly tail stabilizer, and mounting up some horsepower.. Just need to install a servo and get my steering hooked back up. My original setup used a pull-pull system for the rudder. I had a lot of trouble getting this pig to turn the last time I ran it. I feel given the length and width of the rudder, that she should turn pretty damn good... So I'm going to remove the pull-pull and change over to a push-pull rudder and see if I can get a better response from it. I also went through and siliconed all of the access holes where water can get into the other sections of the tub to prevent major water logging.

1QwkSport2.5r

Got her all buttoned up and ready to run for last weekend... But the wind made the water unsuitable to run this pig... But everything is rigged and plumbed, and most importantly - sealed up. Now to find some calm weather and an extra set of hands to run this thing and see what she can do with the new engine.