Terry From Michigan

[TLL]

Hi, I'm new here.
I build 4stroke Powered paragliders for living. Look at 'TERRY LUTKE' on Youtube. Someone suggested my reductions might be useful for air boats..any way just checking in

Thanks/T

[Corky]

Hi Terry and welcome to the site...Looks like you make some fun paragliders..In the one video it really took off across the field...Faster than I'd be comfortable with and I'm pretty adventurous !! .You could easily cross over into the airboating world if you wanted to...

[TLL]

Hi Terry and welcome to the site...Looks like you make some fun paragliders..In the one video it really took off across the field...Faster than I'd be comfortable with and I'm pretty adventurous !! .You could easily cross over into the airboating world if you wanted to...

I'm really trying to learn more about airboat design. I've built a couple airboats by simply parking completed paraflyers on flat bottom hulls. Best performance with a 21hp single cyl Briggs was 20mph with a 170lb 'driver', it never did really plane in deep water. It was a fun project but I earn my living with flying stuff and I had to move on.
here is one such video
https://www.youtube.com/watch?v=iXrTCzbK3Sc
Terry

[Papee]

Welcome to the forums. The only real difference is the amount of drag and matching the hull size to the power plant. You need enough surface area to float the total weight but not go overboard and have excessive drag on the wetted surface when on plane. A wider hull may get on plane a little faster but a narrower hull will have less surface area causing drag.

The hull design also has a big affect with smaller engines. A flat bottom will be faster than one with chines. Creating a small step in the hull where the bottom can create a leading edge also helps with drag. Also the rear portion of a hull is not exactly flat to get more of the pressure off the bottom. I've been trying for a while to come up with a formula for drag vs sq ft of wetted surface but have failed to this point. There are figures out there for a cutting hull but not planing.

There is also engine/prop angle, this is very important. Getting the angle exactly right so there is no force pushing the stern in the water or pushing down on the bow. If the bow is lifting too much it will push down on the stern and cause more drag.

Thats about out it in short form.

[TLL]

here's an engine I was fooling with..it'a a Briggs21hp vert shaft single with a twisted belt to horz prop drive. I tested and flew with this setup for awhile..no problems..not saleable to flying guys Advantage is the low engine cost for 21hp.
https://www.youtube.com/watch?v=fAS1_zkonjk

[TLL]

Thanks. I'm sure there are lots of design caveats. Good advice saves newbs like me from reinventing the wheel..again

[Papee]

There is no wrong experimenting. Keep in mind a few things if you are hoping to market your product later on. Most people want to be able to haul at least two people. Cost is a huge factor. We tend to put a good amount of hours on these setups. Longevity of the long belts and slippage would be a concern there. There are other products out there using horizontal shaft engines and multiple belts that are known to slip. The better reduction drives are using a cogged belt and gears. As I mentioned cost is a big deal, if you are using a smaller engine and have to put on a $600 reduction drive there are better choices.

Luckily all we have to be concern with in our hobby is safety. I enjoy new insights, who knows who or when the next big discovery will come making these small boats more efficient. We have a good bunch of thinkers on here with experience that will weigh in.

[TLL]

There is no wrong experimenting. Keep in mind a few things if you are hoping to market your product later on. Most people want to be able to haul at least two people. Cost is a huge factor. We tend to put a good amount of hours on these setups. Longevity of the long belts and slippage would be a concern there. There are other products out there using horizontal shaft engines and multiple belts that are known to slip. The better reduction drives are using a cogged belt and gears. As I mentioned cost is a big deal, if you are using a smaller engine and have to put on a $600 reduction drive there are better choices.

Luckily all we have to be concern with in our hobby is safety. I enjoy new insights, who knows who or when the next big discovery will come making these small boats more efficient. We have a good bunch of thinkers on here with experience that will weigh in.

I know very little about hulls and water craft, I know a lot about 4 stroke industrial engines, reduction drives & props. I fly with long-belt reductions using banded Vbelts (x style), I've sold these reductions for years on completed powered para-machines. My long belt redrives might be the most reliable available in PPG. Long Vbelt designs have the unique advantage of lowering the horz. CG for safer handling, that is a big deal. Industrial engines are heavy lumps, mounting engines well above the CG cannot be the safest approach.

Selling parts here is not my goal. I don't actually sell engines, parts or drives, but I do want to learn about hull design.

If I post something showing long belt drives or a unique R&D power design, one idea might be to pay attention, zoom into the photo & ask a question, I've been plowing this ground since 2008. Studying photos and asking questions is how I'm planning to learn about hulls.

Terry

[Coyotes-R-Us]

I'm new to the airboat thing to.
I'm going in a different direction.
FLAT Catrermeran hull.
VW motor
Snowmobile Drive

[TLL]

Nice..being from the north my airboat vision is an overpowered glade runner that can rip up water, weeds and dry beaches. My experience with a DIY mini airboat was more like 20 mph, no dry land running, no weeds in sight so I couldn't really check that. I will say +-20 mph felt fairly sporty to me, and probably sounded intense to the nearby land lubbers. Toonies seem like a cool idea to me.

Terry

[TLL]

Can ask the dimensions on the 'toon?

Terry

[TLL]

On my DIY I found I didn't care for the way the hull handled with the air rudder. In sharp turns the boat would tend to lean to the outside and at times try to swamp over the rear outside corner. The next day I tried again but ditched the steer-vane in favor of a longish shallow draft water-rudder..handling was far more precise and the hull tended to carve in the turns. Is that still an air boat?

[Coyotes-R-Us]

Each 'toon is 11,6 by 31"
I the water it is 7'2" x 28"
I plan on the "Boat" to be 7' wide

[TLL]

Thanks for the detail, the design is simple..I like simple

Terry