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Doubledog's building a luftboot

Old 01-03-2008, 11:47 AM
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Doubledog
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Default Doubledog's building a luftboot

Hi gang.
First of all, many thanks to you for the wonderful ideas. Its good to sneak in here & see whats going on. Even have a lot of your pics printed off & posted in the shop for reference.

Some of you might remember me asking questions a year or so ago about scratch building one of these boogers. Actually its been in the works for about six months now and is to the point I feel confident enough to post some pics. A new work bench has helped with the process. Having one bench means moving projects around and it gets tiring.

Here it is. Don't be too hard on me just yet as this isn't a show model. Its only to get out there & have some fun.

46L x 25W x 3.5 Deep

Engine is a Zen G23 and will be setup for a pusher. I've got a 14x7 three blade. Pusher props are limited in sizes but this should work enough to scoot along. I'm going to convert the engine over to a pull start as well to make it a tad easier. Wood is mainly peices of scrap 1/4" ply, cut into stringers with the bandsaw. Decking is 3mm ply as well & will get laminated with West Systems throughout.

Again, don't be too hard on me as this is a relatively cheap project and I'm not wanting to sink a lot into it. You'll notice some of the lines are not perfect & the bottom will get filled in as needed to flatten out.

Best regards,
Jamie


Ps,
I'm mainly a gas boater and have had some ideas about the tank position. Would an IV bag allow me mount it lower or even on the deck? Since the bag collapses wouldn't it make drawing the gas a bit easier?
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Old 01-03-2008, 03:48 PM
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codtongue
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Default RE: Doubledog's building a luftboot

I'm certainly no expert, but I'm thinking you might be a little too big on the dimentions. I think most people are using the prop length plus a couple of inches for the width, I see your using a 14 inch prop so that should put you at 16to 19 inches wide. the length could be drop a few inches as well, maybe a little closer to 40 inches, just my thoughts we'll see what others have to say.
Old 01-03-2008, 04:18 PM
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Default RE: Doubledog's building a luftboot

It will have good slides on the truns no doubt. As stated above a little smaller on the boat would give better prefromance, and at the same time what you have now will run just fine. Just one thing I would change, the 14 x 7 3-blade is going to load your engine some and not let it get up to the power band for the G23, you will have better results with the APC 14 x 6 2-blade.
By the way welcome back, LOL its been some time since we seen you.
Old 01-04-2008, 02:48 AM
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Doubledog
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Default RE: Doubledog's building a luftboot

Notes taken & thanks for the responses.

To think, all this time I thought the measurements were close to where they needed to be. Amazing how you can write stuff down & somehow the numbers change when you start cutting.

If anything I can cut a stringer out from the transom. That would put it right at 40" but the width will still be there. Any suggestions. Mr Gator?

Props, I guess I'll order the APC. Being a gas boater, I'm currious to know how the G23 would act to mods? Just some mild port work. Or is it to my advantage to sell the 23 & search out a good deal on a 26 ?
Old 01-04-2008, 09:46 AM
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Default RE: Doubledog's building a luftboot

As you know with the water prop on a G23 they do take the mods well, but they start to get there power around the 13,000rpm mark and max out somewhere around 17,000 to 18,000rpm's, the air props are designed to work from around 10,500 rpm's to 12,000 rpm's just below where the G23 needs to be. At the same time your boat will run ok with the G23, but much better with a G26. I have tried a few different engines, brands and sizes, so for the best engine I have found for the gas airboats is the CY 27cc. The G26 ran very close to the CY so if you can find a G26 at a good deal go with it.
The ideal size for the G23 IMO 38" x 18" x 2-1/2" the radio box would need to be 3" tall to have room for the 1/4 scale servo.
You have a good start on your boat now and it will run ok like it is.
Old 01-04-2008, 10:05 AM
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Doubledog
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Default RE: Doubledog's building a luftboot

Good posting. I'll work around the engine issues for now. Who knows, maybe a new one will find a new home here
Old 01-05-2008, 12:51 PM
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Default RE: Doubledog's building a luftboot

Cajun Gator & others time to pick your brains a bit more....

We've established the boat is too large for the G230PU that I have. Now, how about if I convert it over to a 26cc or even 27 ? Hull still too large?

How will that effect me in prop selection as well? I'd like to pull this 14x7x3 if possible.


Final note... please confirm some information: I've been directed that the G230PU is an easy conversion to the RC26 or even the CY25 Jug & piston. Only needs longer bolts.???

We're rolling with this & it feels good

.
Old 01-21-2008, 12:08 PM
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Doubledog
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Default RE: Doubledog's building a luftboot

Moving on along.

A few updates and needing input along the way.

1 - I cut one rib off bringing the overall length to 42".

2 - I see now why a lot of you go with a pusher. Seems the rudder assembly will be easier to work with.

3 - Being an old gas boater, I'm going to try using a set of Speedmaster mounts. Had to change them around to get the prop clearance needed.

4 - Next is my tower issues.... Had no choice but to go with 1/2" light ply. When I say light, its not as heavy as normal stuff, but quite strong. Hope it isn't overkill. Once its situated and decided on everything, I'll cut a few more lightening holes.


Hope to use a 500ml gas bag under the engine. Other than that, I'm burned for ideas. I'll go to the shop and stare for twenty minutes at it trying to get the proper thought path.

Chat next weekend.
Jamie
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Old 01-21-2008, 12:12 PM
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Doubledog
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Default RE: Doubledog's building a luftboot

Few more.

Give me some feedback as I'm learning. Btw, this is probably the most fun I've had with a bandsaw & drill sanding disks
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Old 01-21-2008, 02:49 PM
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Default RE: Doubledog's building a luftboot

It looks like you're doing a great job.[sm=thumbup.gif]
The angled sides are a big plus, a lot of the scratch builds don't do that.
If it's a little too wide still, say the heck with it, it should be fine.
Old 01-21-2008, 03:00 PM
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Doubledog
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Default RE: Doubledog's building a luftboot

Thanks for the words.
I'm no wood guru and more or less throwing it together quickly. Its cheap enough (main cost being the epoxy). After the numerous posts by you g-uys, I figured this one would be a learning block and make changes to the next one.

Rock & Roll.
Old 01-23-2008, 08:31 AM
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Default RE: Doubledog's building a luftboot

Looking good mate just thought id check on your progress ,seems like your doing a good job.Is it your own design ? also while im no expert on airboats i still think your motor will run ok on that boat,sure it might not have the power of the others mentioned but it will get it moving just fine.I ran tame .46 nitro on an airboat my mate ran a powerfull one and his went faster but mine still went well.Just my thoughts on it mind .
Old 01-23-2008, 08:52 AM
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Doubledog
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Default RE: Doubledog's building a luftboot

Marty, glad you you like it. I'm yet to fire it up but just in case it doesn't have the power, I've got a new RC260 jug for it. In all honesty as long as its fun and moves along good I'm ok with it.
Old 01-23-2008, 11:39 AM
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Default RE: Doubledog's building a luftboot

It looks great, I'm sure any of the engines you mention including the 23 would push it along great. don't forget to put some kind of floatation(foam or pool noodles cut up) into that hull, so you won't have to wave bye-bye, if for some reason something happens.
Old 01-23-2008, 12:17 PM
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Doubledog
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Default RE: Doubledog's building a luftboot

Yeah, no doubt on the noodles. Plans are to stick them in the sides and then deck over them. Can't wait for the weekend to go play... ahem... work some more.
Old 01-27-2008, 03:12 PM
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Default RE: Doubledog's building a luftboot

still chugging away at it.

This weekend got the tower together & epoxied in. Using West Systems 206 and this stuff is good. Look under the engine & you'll see the IV bag that just layed in there for pic's. Its a challenge coming up with ideas and now the most interesting is going to be building the rudder system.

Any ideas on how to do it? Hope to make some brackets off the back of the tower extended out to two verticle rods. Fins will be out of thick stock aluminum.

How tall should the fins be? Swinging a 14 inch prop so I'm guessing... der' 14 inches?

Btw,
Once things started coming together, its pretty dang big. Now I'm worried about the CG. Haven't put it on a balance stick yet, but by looking, it seems too far to the rear. Will try to push the radio up front as best as possible.
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Old 01-27-2008, 05:15 PM
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Default RE: Doubledog's building a luftboot

You are going to enjoy this boat, looking real good. As for the CG do worry to much about that. As you know with the water prop boats, most start at 30% but on the airboats, thats a all new set up, since there is so much leverage up high. Your engine may be a tad on the back side, but again don't worry to hard. One of the main advantages to the airboat is again the leverage the engine has. At worst, if the engine was to be set level to the hull, you may have some hop. When you set your engine mounts, just set the rear mount a little lower than the front, 1/8" to around 3/16". It is a good idea to have slots where the bolts hold the engine mount, so that you can adjust as needed.
Not to sure about needing longer bolts for the new jug. There is a shim that fits between the jug and the crankcase, and it is less than 1/8" thick.
Your on the right track for the rudders, 14" tall X 2-1/2" wide. Regurlar cabinet door hinges work fine and you can still use shims to get the correct pitch and toeing that may or may not be needed. You will have to run the boat first to see if rudder adjustments are needed.
Another thing that you may want to do before decking. At the transom to bottom, this area takes a lot of abuse and it is the main area that may pop loose, it will not hurt anything to add a little extra epoxy or laminating extra supports.
Your boat is looking really good, and you should be race ready in no time at all.
Old 01-28-2008, 02:19 AM
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Doubledog
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Default RE: Doubledog's building a luftboot

Fantastic read you put together. Lots of good info that I'll come back to.

Engine trimming / balance point.... Wonderful. I'm amazed at this idea. Initial thoughts were to use weight up front and set the engine level. I'll definitly cut slots for adjustments on the rear and shim as needed.

Door hinges.... theres an idea. Simple and easy. To think, I've been racking my brain on how to come up with something on the mill. I'll look into the simplest way for this boat.

Rudders.... 14.5 x 2.5 Perfect.

Bottom area reinforcement..... Will do.

This is turning out to be one of the most enjoyable projects to date. No rush, but its coming along quickly.
Jamie
Old 01-28-2008, 08:41 PM
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Default RE: Doubledog's building a luftboot

laminating another 1/8" ply to the transome and glueing that also to the bottom, just something to give more area at the glue point between the bottom and transom.
Old 01-29-2008, 06:05 AM
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Default RE: Doubledog's building a luftboot

Jamie just use some glass matt strips to rienforce the joints at the transom,shes looking good so far mate .I know you will probably be running on land and water but for on water you can extend your rudders so they enter the water and it will give better turns on water.My mate came up with some rudders that he could change to run on water or land if i can find the sketch of his idea ill post it.I think the idea was he can us both sets of rudders when on water and the water rudders can be either removed or folded up out of the way on land maybe.He made this boat using airplane floats with a large .61 nitro i believe but he never did finnish it due to some personal troubles,pitty as it was looking good.
here you go.
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Old 02-04-2008, 12:18 PM
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Doubledog
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Default RE: Doubledog's building a luftboot

Chugging away, slowly but surely.

Got the rudders built. As Mr Cajun Gator said, I went the simplest route & used hinges. Fins are 15 inches x 2.75.
Engine installed and moved as far forward as possible.
Reinforcement in the bottom around the engine as well.

Try to overlook the stern. I'll laminate another peice on the back to clean it up a little.


Ideas needed now as to connect the fins together and for a control hook-up.
Also, does anyone have an extra 14x6 laying around? Don't really want to drop an order at T-ower just for this. The one thats on there now is a 14x8 I had laying around.
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Old 02-04-2008, 03:59 PM
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Default RE: Doubledog's building a luftboot

Wouldn`t it cost the same ,if one of the Guys had one,as it would if you placed an order? what about something like this-

http://www.shops-4-you.de/rc-verbrenner.html


or somewhere in Germany..Your going to want to try a few different props, and Brands anyways...just an idea
Old 02-05-2008, 02:29 AM
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Doubledog
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Default RE: Doubledog's building a luftboot

Hi D',
Yes, I know where the local hobby shops are at within a 75 mile radius. All things considered including exchange rates ($ - Euro)... I'm still much cheaper ordering from the States. Plus the fact that if I go into a hobby shop or shop online, I can't buy just one or two items[&o]
Old 02-05-2008, 02:46 AM
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Default RE: Doubledog's building a luftboot

I hear You..If I order online, or go to the Hobby Shop ,The 100 mile round trip costs me the same as having things Shipped..I also don`t recall ever leaving the store, or placing an order of 1 item.I also have to make the Trip, or the price of shipping worth while..Sorry that ,I`m of no help to you..

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