A possible Skimmer-boat?

[leviterande]

Hi, did anybody see or make such a hover-craft-airboat.

The idea is simply to take an ordinary airboat and guide some air from the propeller down to under the hull without using skirts. that should reduce the friction a bit over the water , but how much?

the idea is NOT to hover the boat any height at all, but rather to create a very thin layer of air to reduce the friction between the hull and water and therby the boat should go with less effort and better acceleration and top speed.. Any thoughts, experiences?


Kalle

[leviterande]

I really find it strange that this idea seems to be even worse than a standard airboat.

and that is based on my rc models prototypes.

I tested first an ordinary airboat with a brushless motor and it just glides fine on smooth surface.

HOWEVER when I guided a small portion of the "propeller airstream" down below the craft , the modified airboat wont move! forward.

it seems like the sacrifice of forward thrust did not get compensated by the lesser friction beneath the airboat. In other words, what happened(as I believe only) was that the friction didnt decrease enough and the forward thrust decreased enough to not be able to propell the craft forward...hmmm.. not sure if I really am correct but everything shows that.

[messabout]

If you put enough air under the boat to support it, or even partially support it, you will have introduced steering problems. An airboat will slide sideways as it is. Lift it to or above the surface and directional stability will be lost. Some sort of fins or runners will be needed to restore steering ability. Underwater appendages defeat the purpose of airboats. Airboats operate well enough the way they are presently built.

[leviterande]

right now the problem is, that i dont even get the slightest of "reduction of friction" beneth the hull and therfore it will hardly slide freely yet. .

Anyway, when there will be just a little bit reduction of friction the airboat should move easier one water and snow/ice. but one of the chief goals of mine was to increase the speed of the airboat by reducing the friction beneath it just a little bit without any hovercraft thingies.


considering the direction stability, there are hovercrafts and they work fine. this airboat will not come as close as "free as an hovercraft" and thus will only be partly lighter and easier to plan fast on water..(?)

[tom kane]

Why not have a horizontal prop on your airboat? Use a tilting ridgid rotor for direction control.and lift.No cyclic pitch control needed but a collective pitch control would be good.

[leviterande]

tom, that is way complicated and I try to make it as simple as possible. only an ordinary airboat with the added rear ducting to duct the air below the hull.

[tom kane]

A very simple tractor airboat.You will need to use a rudder or a keel to steer it.

[tom kane]

You could make a big splash with this design.SURFACE PROPULSION FOR REAL..

[leviterande]

Hi Tom, sorry , do you really mean to have a part of the prop in the water?!!!!!




that would make a beautiful big water/engine splatter mega explosion..

[tom kane]

With about 6 inches of the prop running in the water (when it is Available) makes a super surface-piercing propeller.When you go over bars or shallows you still have the thrust from the air,but less efficient.Running a propeller in the shelter of the boat hull still works well.

[leviterande]

hav you ever seen a 5 or 8 foot air propeller touching the water in any boat or at least is there any such design that was tested. for me this sounds very dangerous

[tom kane]

There have been hundreds of thousands of air boat designs in popular mechanics magazines for use on water ice and land over the years. 50 years ago we had a 10 foot air boat punt style using a large building ventilator fan four feet dia which when loaded ran in about 6 inches of water which was more efficient than any other we ever saw.A 5-6 old indian engine drove it along on water and up the beach.It was of no real novelty to us and we did not think to take any picture of it,we were constantly rebuiding and making all sorts of things.

[Yellowjacket]

Originally Posted by tom kane

You could make a big splash with this design.SURFACE PROPULSION FOR REAL..

Really bad idea...

A aircraft type of propeller runs at a tip speed of close to the speed of sound. The tip speed of a surface piercing prop is a whole lot less. An aircraft type of prop would be damaged if it was impacting the water and if it went slow enough to not be damaged it couldn't generate much thrust in the air.. The slip in the air is a lot more than in the water, so if the tip hit the water it would be a huge shock in terms of thrust, and never mind how much bending stress you would be putting into the blade....

In short, forget that one...

[leviterande]

Yellowjacket, furthermore, the torque and rpm of an air propeller is different from a water propeller. i just cant understand how it could work in reality

[BWD]

hey dorks.
you need another shaft or belt off yer motor, to drive a blower to create high pressure air to inject through little holes somewhat aft the stagnation point. Use whatever cheap automotive supercharger you can get, or buy an industrial pos. disp. blower. Alternative if you've a good alternator, electric blowers are available.....

Please Pm me for details on how to pay my consulting fee.