R/C airboats

Wing:

You like it? Go for it!

I'll pass, thank you.

I blame it all on you fellas,,with your unrestrained talk of airboats.


Yup, an original Hydroblaster, still NIP.



Just one little foam piece tore out of that right sponson, and that was stuck in a bag in the box as well so it can be reattached. A couple rash marks from it being removed from the box, but all the bits are there including a amazingly good sheet of decals as well as all paperwork. This one has the rubber donut throttle ring muffler, that was only made one year I believe due to a copyright infringement. A water rudder setup for steering.

For all the folks with a handfull of engines in there box, just sitting there, this would be a really easy one to make. I was lucky enough to find one. Pick up a Mini-mart $2 styrofoam beer cooler or ? and cut and glue. A couple of disposable mini servos hot glued in, build a craft plywood/balsawood engine mount to glue to the styro, a few other bits and pieces and your afloat.

Kim wrote:
Hey Dins,

I found the "plan" for the Lil Swamp Buggy. The boat comes with a large instruction sheet, without full-sized templates, but I had intended to build several, and so had traced the outline of the parts on the backside. They should let you cut out your components. I'll make a copy of both sides and post them to you. Don't think it should be too expensive, but I'll check with you before I send them.

Later! Kim

G'day Kim. The plans arrived - at last. Thanx heaps for your time and effort.
Dins

WingingIt74 wrote:how about this one

http://www.ebay.com/itm/vintage-wooden-boat-gas-engine-cox-estate-find-as-is-/220970616543?pt=Radio_Control_Vehicles&hash=item3372e006df#ht_500wt_1058

man thats cool, is that a baby bee or a peewee? looks fast

Cool boats. I built a Dumas Hot-Shot tunnel hull with K&B .21 outboard. Boat went together very nicely and parts fit was very good. It was a beauty, but never ran it as friend bought it. Tucson,Az. is home of Dumas models and they have been here a long time. I here their new lazer kits are pretty good.

Mitch, it is a babe bee.

dankar04 wrote:Cool boats. I built a Dumas Hot-Shot tunnel hull with K&B .21 outboard. Boat went together very nicely and parts fit was very good. It was a beauty, but never ran it as friend bought it. Tucson,Az. is home of Dumas models and they have been here a long time. I here their new lazer kits are pretty good.

I recently received a Dumas Big Swamp Buggy kit. I was appalled, to put it politely. The plywood used is mostly no better than fire wood. It's all warped, splintered and mismatched. It's not die-cut so much as crushed. It's an insult!! More than 75% of the parts will have to be replaced by ones I make myself.

As I live in Oz and $71 of it was postage it's not viable for me to send back. I'll content myself telling as many people as possible what Dumas' products are really like.

Do I sound a little pi**ed off?? I am!!

Tell them about it and show them pictures.
They should replace it.

dinsdale wrote:

dankar04 wrote:Cool boats. I built a Dumas Hot-Shot tunnel hull with K&B .21 outboard. Boat went together very nicely and parts fit was very good. It was a beauty, but never ran it as friend bought it. Tucson,Az. is home of Dumas models and they have been here a long time. I here their new lazer kits are pretty good.

I recently received a Dumas Big Swamp Buggy kit. I was appalled, to put it politely. The plywood used is mostly no better than fire wood. It's all warped, splintered and mismatched. It's not die-cut so much as crushed. It's an insult!! More than 75% of the parts will have to be replaced by ones I make myself.

As I live in Oz and $71 of it was postage it's not viable for me to send back. I'll content myself telling as many people as possible what Dumas' products are really like.

Do I sound a little pi**ed off?? I am!!

I would email pictures, tell them your story and where you live, the moneys involved and see what they do.

i just now getting into model boating, after seeing this thread i scratchbuilt one of my own it has my .049 golden bee in it for power, i got the chance to do a maiden voyage of it today. After 30 minutes messing with the motor she finally started, i set her into the water and when she started to move the front dug into the water. so quick thinking told me to do a 180 and come back to shore, to say the least she flipped. I now know that it is mostly water proof
the boat messures 16'' long, 6'' wide body is 3'' tall with a 7'' tall motor mount. Can anyone help me figure out why the front dug into the water when the motor was running, and also is the body of the boat wide enough?
thanks

mitchg95 wrote:
the boat messures 16'' long, 6'' wide body is 3'' tall with a 7'' tall motor mount. Can anyone help me figure out why the front dug into the water when the motor was running, and also is the body of the boat wide enough?
thanks

Your boat proportions are all wrong (for an airboat). Too little beam, too much freeboard, engine pod too high and probably the engine pointing at the wrong angle too. Remember, photos speak a thousand words. A bit too much detail to cover in this thread. Join this forum http://www.rcairboats.net , read and ask. There's a huge amount of combined info on airboats there. But don't forget to come back here for your Cox addiction.

Cheers
Dins

Some pictures if you can Mitch.

Weight placement is a big factor, along with your engine mount placement.

Your engine mount thrust angle should be parallel with the boat, then you can add washers behind the top and/or bottom of the backplate to adjust and tune that angle. You want a bit of down thrust on the stern,,or in other words,,to have pressure pushing the back of the boat down,,just slightly at full sing on the motor. Engine torque will cause it to turn harder in one direction than the other, you cant really eliminate all that, but again, you can add washers now to the sides of the backplate to adjust it a bit.

Float it in a tub of water and get it to float level, then start moving weight back to get just a touch of stern down with just weight placement. you might have to move it forward or back after that to get it tuned right in the water at speed.

At first glance on your specifics, your a bit narrow and a little to tall in the water. The Dumas lil swamp buggy is 7.75 in width(beam) and 18" in length, and at first guess I would say that the sideboards are about 2" tall,,give or take a little each way.

Its your custom build boat, so some tweaking and redesigning will have to take place,,but don't give up.

Go and have a look over here. http://www.rcairboats.net/phpBB/viewforum.php?f=6&sid=4839e0c268c3e5a5bdcdab245c6d1301 There really is a lot more to it than one would think at first glance.

PV Pilot wrote:Some pictures if you can Mitch.

Weight placement is a big factor, along with your engine mount placement.

Your engine mount thrust angle should be parallel with the boat, then you can add washers behind the top and/or bottom of the backplate to adjust and tune that angle. You want a bit of down thrust on the stern,,or in other words,,to have pressure pushing the back of the boat down,,just slightly at full sing on the motor. Engine torque will cause it to turn harder in one direction than the other, you cant really eliminate all that, but again, you can add washers now to the sides of the backplate to adjust it a bit.

Float it in a tub of water and get it to float level, then start moving weight back to get just a touch of stern down with just weight placement. you might have to move it forward or back after that to get it tuned right in the water at speed.

At first glance on your specifics, your a bit narrow and a little to tall in the water. The Dumas lil swamp buggy is 7.75 in width(beam) and 18" in length, and at first guess I would say that the sideboards are about 2" tall,,give or take a little each way.

Its your custom build boat, so some tweaking and redesigning will have to take place,,but don't give up.

cool thanks for that info, the boat weighs 14.4 oz auw

mitchg95 wrote:cool thanks for that info, the boat weighs 14.4 oz auw

Sure, no problem.

I did register on the rcairboats.net forum that dinsdale linked to,,some good stuff on there. Lurked around and did some reading.

PV Pilot wrote:

mitchg95 wrote:cool thanks for that info, the boat weighs 14.4 oz auw

Sure, no problem.

I did register on the rcairboats.net forum that dinsdale linked to,,some good stuff on there. Lurked around and did some reading.

cool, i might join them later today

I have a kit I bought when I was a kid. It's a land version of an airboat with an outer space theme. I'll post some pics if I remember. Maybe another father/son project

I know that you guys thought it would be cool to have a teedee .010 powered airboat, that got me thinking. I dont have any .010's but i have a redtank peewee to throw into one, i have to design it and im thinking the dimensions should be as follows... 10'' length, 5'' wide, 2-3'' hull size, and a 3.5-4'' tall motor mount with single rudder. motor will be in tractor set up and not pusher, what do you guys think on the dimensions. FWI i will be using the cox .020 3 bladed prop that Bernie offers at COX international. Thanks

I'd push it out to about a foot in length. You should aim at about 2" wider at the chines than the diameter of your prop. That means about 1" each side wider than the prop at the chines. You want to keep the engine tower as low as possible. You only need about 0.25" clearance over the deck. The CofG should be at around 33% in from the transom. This will move of course as you burn fuel. The centre line of your cranckshaft should be anything from parallel to your deck to around 3deg up. You'll have to experiment with this. As you lift the front of the engine it'll push the bow down. It should also be along the centre line of the boat. There'll be no torque reaction to be bothered allowing for.

These are good rule-of-thumb starting points, but fine tuning will be required.

Is there a step by step build plan to build an airboat out of balsa? I got a lot of engines laying around and whould love to build one. However im not an expert builder yet.

I already build an boat which should be able to recover the boat when he ran out of fuel. It got a hook which is controlled on distance.

PV Pilot wrote:
You want a bit of down thrust on the stern,,or in other words,,to have pressure pushing the back of the boat down,,just slightly at full sing on the motor.

You'll probably actually want the exact opposite of that, "... at full sing on the motor." They do tend to get airborne quite often at full speed.

PV Pilot wrote:
Engine torque will cause it to turn harder in one direction than the other, you cant really eliminate all that, but again, you can add washers now to the sides of the backplate to adjust it a bit.

Engine torque will have negligible effect.

PV Pilot wrote:
Float it in a tub of water and get it to float level, then start moving weight back to get just a touch of stern down with just weight placement. you might have to move it forward or back after that to get it tuned right in the water at speed.

CofG at about 33% in from the transom.

PV Pilot wrote:
At first glance on your specifics, your a bit narrow and a little to tall in the water. The Dumas lil swamp buggy is 7.75 in width(beam) and 18" in length, and at first guess I would say that the sideboards are about 2" tall,,give or take a little each way.

You want beam at the chines to be around 2" wider than the diameter of your prop - 1" each side. Keep everything as low as possible to keep the CofG low.

mr_cox wrote:Is there a step by step build plan to build an airboat out of balsa? I got a lot of engines laying around and whould love to build one. However im not an expert builder yet.

Have a look at these kits:-
http://www.pacificbalsa.com.au/gallery/Boat%2BKit/challenger/58880
http://www.pacificbalsa.com.au/gallery/Boat%2BKit/dictator-boat-kit/53449
http://www.pacificbalsa.com.au/gallery/Boat%2BKit/sabre-boat-kit/53462

Any one of these is easily modifiable to become an airboat. I have the Challenger and the Dictator which I'm building as airboats. Some parts I'll do in 1/16" or 3/32" ply because of the stresses of a much more powerful engine than the standard electric motor.

Apart from that, go here for a look and ask some questions.
http://www.rcairboats.net/phpBB/index.php