1 of a kind 37" CF Dragboat

[flraptor07]

I was right about the HP and Length but not the weight, the real ones weigh about 3000lbs. I just did some googlin'.. Those mounts are nice! I've started using those front plates instead of the watercooled ones my GP400 has one in it.

[Fluid]

...you're talkin' 8000hp in a 22" boat!......I was right about the HP and Length but not the weight, the real ones weigh about 3000lbs...

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[drwayne]

2.66Hp per 1lb
37" vs 22' is close to 1/6.
1Hp = 746Watts

I leave the maths to you.

[flraptor07]

That would be roughly equivelent to 1333hp in a 37" boat, That's scaled down to 1/6 if I'm figuring right. 1/6 of 22' is actually 36.6" and 1/6 of 8000hp. is actually 1333.333333333333 etc. You guys get the idea.... holy crap! but for it to be true scale our boats would need to weigh 500lbs. and we know they're not going to be anywhere near that, so we won't need anywhere near that much HP to move them the same. I'm guessing these boats will be about 15-16lbs RTR.

[Fluid]

You cannot scale down horsepower or speed directly/proportionally since time is involved in the measurements; time is not involved in scaling down length or weight. I have the hp scaling formula somewhere, I'll find it when I get home. Doc's hp/lb makes more sense, especially since 1300+ hp won't fit in a 37" boat.....


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[RandyatBBY]

Zero torque roll if built like the full size boats..

[ATTACH=CONFIG]124109[/ATTACH]

Interesting the drag boats have clock wise on the starboard side and counter clockwise on the port side.

I was talking to Robert Tuttle the other day he was saying that the hydros have twin turn fins on them to keep them running stright. I have looked at a lot of pictures and never saw them.

I hope you do well with your Gallbladder surgery, good luck!

[flraptor07]

You cannot scale down horsepower or speed directly/proportionally since time is involved in the measurements; time is not involved in scaling down length or weight. I have the hp scaling formula somewhere, I'll find it when I get home. Doc's hp/lb makes more sense, especially since 1300+ hp won't fit in a 37" boat.....


.

If we went with the 2.66hp per lb. then we'd need about 40hp to be equal

[drwayne]

If we went with the 2.66hp per lb. then we'd need about 40hp to be equal

so... 8S50/100c5800ENTROPY =19.5KW on launch
so plan to build ~10lb LOL

here are pair of your sponson turn fins
firebird.jpg

[olwarbirds]

I just caught that 22inches instead of feet good catch fluid !!... Tks Randy, I'm home now, a bit sore but all seems good. ...Tks Wayne, for formula and pic, thats the same pic I was looking to post. I already have 2 small turn fins that I'm mounting. Chris, this is interesting trying to work out the pwr to weight ratio that would be equal to real ones. Have you ever mounted a Neu motor to those mounts, my 1521 has the wider screw spacing... DJ

[flraptor07]

Hey DJ, Glad everything came out OK and hope you heal quickly. No I've not put a Neu on one of those new mounts yet but I'm sure it won't be any real issue, that's what the little rat tail file is for or a dremel with a real small burr... I fixed the inch to feet boo boo.. I didn't catch it till you posted about fluid catching it... Duh...

[drwayne]

You cannot scale down horsepower or speed directly/proportionally since time is involved in the measurements; time is not involved in scaling down length or weight. I have the hp scaling formula somewhere, I'll find it when I get home. Doc's hp/lb makes more sense, especially since 1300+ hp won't fit in a 37" boat.....


.

22' to 37" is closer to 1/7 scale (37"x7~21.6') ..so scale speed is~ 34mph LOL
stick with power to weight and build accordingly .


Apologies DJ .. just found my cad viewer..

Plan is 55KW(74Hp) 10S2P in 44" twin engine, twin prop.... like ?

d3-4.jpg

1655873_10152751529002456_5966664917639258278_n.jpg

d3-5a.jpg

your belly wound is nothing but a scratch DJ .. . Im in for a disarticulate knee revision end of Jan... :grimace: lol
Followed by plenty of time at home to build my new boat

[olwarbirds]

Wayne, tks my friend. Is that the hull design you told me about, that I could buy eventually ? I like it ! 44" is a nice size to work with. That design would definately have more buoyancy and with the rear sponsons, the torque roll would be more controllable I would think... 74hp that setup will definately launch.... DJ

[drwayne]

Wayne, tks my friend. Is that the hull design you told me about, that I could buy eventually ? I like it ! 44" is a nice size to work with. That design would definately have more buoyancy and with the rear sponsons, the torque roll would be more controllable I would think... 74hp that setup will definately launch.... DJ

No torque roll with counter rotating engines.

and, in answer to someone above.. the props rotate outwards at top, to stop the backend hopping down the straight ..

2am here.. working ....
1/7 of 1000' is just 142' ,, from experience that is second or third touchdown after launch

[olwarbirds]

Tks guys ...yup Wayne just a few scratches...I have definately decided to go twins, I did some weighing and with twin 1521's 4 4S so I can adjust cg looks like its going to be less than 15lbs....its going to take me a bit longer to do this build now, I need another 1521 1577kv, 2 hv esc's and all the other hardware for a twin. I think its going to be worth the investment and time. I'm sure going this route will take away alot of torque roll probs that the single would of created. I've been shopping for some colored cf plate, its a bit costly ! It almost seems that it would be cheaper to make my own... DJ

[flraptor07]

I'm deffinetly doing twins too, it's the way to go in this application. That red TFH in the pic above is the Toxic Rocket, back in October last race of the year they crashed it and the driver Glen Wilson is just now getting out of the hospital. Broken back and a couple of surgeries but they say he's gonna make a full recovery and be able to race next season. https://www.facebook.com/pages/Toxic...70379976411832