1QwkSport2.5r

These boats are really tough to make unique. I want to build one thats of my own creation, with some styling cues taken from other builds. This is my Rough draft carved from 2" styrofoam. I figured I'd use styro because its easy to sculpt and I can get my overall design figured out before doing the hours and hours of drawing and then months of building. Overall length is 36" of the center tub and 14" on the sponsons. Overall width has yet to be determined. I figure it'll end up somewhere between 20" & 22". I still have some modifications I'm going to make to the foam before I will be happy.. once I am happy with it, I'll draw it out and (hopefully) build it. Framework will be mostly balsa with some 1/8" and 1/4" plywood for supports. I'm going to skin it in 1/32" or 1/16" plywood and stain it a different color than my last one.

Power will come from my new TT .46 Pro on a mid 10" - low 11" prop. I originally wanted to invert the engine but I'm gonna end up cheaping out and turn it sideways 90* so the exhaust is either on top or bottom.

Here's my foam rough draft:

SFC K

Looking good Tim!

1QwkSport2.5r

I didn't know you were on RCU.. lol... nice seein' ya here, and thank you!

SFC K

I see you have been here a long time too. Crazy! Well hopefully next spring before I go I will see it run! LOL

1QwkSport2.5r

Oh, for sure. By then I'll have the flatty all dialed in and we could run both of them.. It will probably take me 2 weeks or so to get the design all finalized and drawn and probably 2-3 months to build it.. I'm hoping to have it built by my birthday (March 28th) so when the lakes and ponds ice-out, I can go run right away. I found another lake to run it on in Eagan. (This lake is aerated in the winter, so the ice comes off pretty quick in the spring.)

I've got a build thread going here, RCAW and GP and as I go I'll update all 3.

Got RPM

I strongly recommend that you do not use balsa in your build. It is too weak and in a crash is more likely to fail. I know, I used it in a water-prop SAW boat and crashed at 80 mph - the boat broke apart. Use basswood and liteply instead, and don't worry about a few extra ounces of weight, it is meaningless. Strength is far more important. The boat looks way cool so far!


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SFC K

Where does one buy Basswood and Liteply? Never heard of them before.

1QwkSport2.5r

I will keep this in mind. I'll be going shopping for wood soon, and my LHS carries all different sizes of that stuff.
Hub carries it - over by the model rockets stuff. Its used in Airplanes. The plywood I used on my flatty is what they use to skin the wings on r/c planes. (for those that build their own)

SFC K

Cool! I will have to check that out this week. Have some parts on order.

res3567

I run an Aquacraft Airforce with an OS .46 AXengine. It originally came with a GMS based Aqucraft mill....but I replaced it cause it had issues...anyway....It came stock with an 11x8 prop...which was way slow. So I tried a 10x8 and a 10x6 ...thanks to the guys on this forum, and found the 10x6 to be way faster...IMHO.....

1QwkSport2.5r

I'll probably be running a 10x6 on it, I also have a 10x8 and I can get an 11x4 or 11x5 if needed. I havent got the TT .46 broke in yet, so I haven't tached it yet. Once I get 10 heat cycles done on it, I'll tach it on the 10x6 and 10x8 just for a little reference. I'm going for speed on this one, so the smaller props are gonna be the ticket.

res3567

Try em all....and judge for yourself. I recently went over to the "Dark Side"...prop in the water boats. My poor airboats ( I have two Airforce...the other one hasan OS .55AX with the samesize prop)justs sits now....but I will firethem up one day...I am so consumed by my new boats....a Deep V mono and a Hydroplane. I am going to give my brother one of the airboatsto have someone to run with and I am excited about your boat. You could say I have the best of both worlds...maybe....but your progress will speed up my renewed interest in the airboat hobby as the other boats engines ae very finicky at times....and I have had more bad days than good....compared to my airboats.

1QwkSport2.5r

I will end up running what I got and buying 2 or 3 more I'm sure. I like to pick the brains of the guys that have ran these engines to get an idea of what they ran in a plane. In a nutshell, its the same game. Its all about thrust getting the beast moving. Smaller props spin faster but at a sacrifice in thrust (in some cases) because of the smaller diameter. Obviously if the engine can spin the smaller prop better than the bigger one, it may net more thrust..

I don't consider water-propped boats the "dark side". Its still a boat, and I would like to build one of these with an outboard at some point... I'm building the airboats because I have a bunch of airplane engines that were free or cheap. With some ingenuity, skill, and time you can build a air-propped boat to go pretty darn fast.. Although a high-end .21 inboard will probably spank even a light fast .61 airboat, (to me anyway) its the fun of building something from scratch, have it float, and better yet run well. I think my boat collection will end up being 3. 1 flat bottom, 1 hydro, and 1 deep V outboard. If the hydro turns out good, I might build a bigger one for a bigger engine... I'm gonna make a few mods to the foam and start drawing soon. I will post pics of the build as I go.

res3567

When I say "Dark Side" I mean as to the airboat forum. I got started in this hobby with my airboats....and I stillhave a foundness for it. However, I have notfound a whole lot of people who do both.....but anyway.....still wanna see your project. Very interesitng indeed!

Check it:

1QwkSport2.5r

Some progress on the "mock-up".. here's where I'm at right now.

1QwkSport2.5r

I drew up some plans and started laying out the frame. I made some adjustments on some of the dimensions - Sponsons will be longer, tub will be a little bit wider and the rake angle changed some. Most of the frame is 1/8" liteply with some 5.5mm ply in the crucial areas. Balsa is used for the outer framework.

I made a jig on a sheet of 3/4" sanded plywood and screwed down a few pieces of wood floor scraps to make the template. (Flooring is milled super straight and isn't bowed or bent) I laid wax paper down inside the jig so any epoxy that drops down won't glue the frame to the jig. I made a top jig to drop down unto the bulkheads to keep them straight and square (not pictured). I have a few more pieces to make for the jig to set the bends for the front and rear of the frame to get the rest of the bulkheads set. I havent come up with a name for it yet.. I have to make sure its going to be worthy of a name first...

boatnut

    I like your setup so far. What have you in mind for engine mount and location?
I am going to build one along the lines of a JAE rigger. That is my intention anyway.
A rigger built by Hooty on another forum, caught my eye. I will; be incorparating
a lot of different ideas from other builders. I will be using a small engine. I love airboats.
Not  fast ,just fun.
I will be watching your build

 
                  Having this much must be illegal
.

1QwkSport2.5r

Hooty's 85mph rigger gave me some inspiration for this build-up. I'm going to use a radial mount with the engine sideways with exhaust on the bottom. I should have all of the bulkheads glued to the bottom of the boat. After the glue sets I'll glue the top frame rails on and have the basic frame structure done. Once I get the frame of the tub done I will make the other jigs to build the sponsons. I have all of the bulkheads cut already, just have to glue and wait glue and wait. It should have some sort of shape to it tomorrow.

Power will come from a TT pro .46 on a Jett-Stream pipe. The engine might get a little port work done if it doesnt hit 50mph.

1QwkSport2.5r

Here's some perspective. Frame side by side with my foam "dummy" boat.

1QwkSport2.5r

Got the rough frame done for the center tub. Going to start the Sponsons next so I can decide where exactly to put the boom tubes.

boatnut

The build I am designing is  going to be simialer to your design.
Have you worked out the fuel delivery problem? I believe I will go with the perry
pump. I can adept it to a smaller engine.
Thanks crispyspa, for the idea. I think using exhaust preasure, will
lead to throttle problems. I would  like to test stand the idea though.
I just hate  having to retrofit if something dosen't work.


     Having this much fun must be illegal

1QwkSport2.5r

I'm not 100% sure what I'll use for fuel delivery. The Perry Pulse pump is $30 and would allow you to put the tank on the moon if you so choose. (exaggerated, I know.) Only downside to this method is having to drill and tap the backplate for the pulse fitting. I will most likely do it this way for "insurance". Boat retrieval sucks.
This is what was recommended to me from the guys in the glow engines forum:
http://www3.towerhobbies.com/cgi-bin...&I=LXDG59&P=ML

1QwkSport2.5r

I almost have the sponsons done. I have a little work left to do on the front of the sponsons, then its on to boom tube mounts and frame reinforcements. I will probably cover the bottom of the tub and sponsons in liteply first and put 1/32" birch over everything. I tried keeping it as simple as I could.

1QwkSport2.5r

Little more work done.. Sponson frames are almost done. Tub needs a little more work before I install the boom tube mounts but this is where I'm at now.

1QwkSport2.5r

So I did some messing around and this is where I'm at so far.... I still have a few things to do before I start skinning it but its coming along. I think I might put a layer of 1/8" liteply across the bottom in the front of the tub with 1/8" balsha sheet for the back 2/3 or so. I think that will give it a bit more rigidity since the booms get the brunt of the friction. Weight of the hull as pictured is 1lb .75oz.