Ram Air Sponsons?

[Propjockey]

OK...everybody put your thinkin' caps on. After looking at the pics of sponson steps in the outboard forum, I got to thinking.....what would happen if you forced air (ram air) into the void created by the step?

Run a tube--say 3/8"--through the center of the sponson with a scoop on the top side. Exit the forced air at the apex of a V-shaped step.

Would this force a pad of air between the water surface and the sponson, creating a hovercraft effect? ???

Pros? Cons? Have I totally lost it?

 

[wswatzell]

I would think that it would create a pad of air under the sponson. It would be even better if it created bubbles. That would be like running the front sponsons on ball bearings. Another question would be would it be legal to race? I’m not familiar with the race rules yet. It sure would be fun to test though!

Wade

 

[TimD]

What about using pipe pressure just like a fuel tank?

 

[Jimboat]

There are full scale tunnel boats that utilize a method of "ventilation", in an attempt to reduce drag of the sponsons. These types of features have shown some success, but are not always advantageous. In choppy water, for example, there is likely to be no advantage at all. Also, the advantages of steps, when properly designed, are significant, and the designer would wish the sponson at that location to generate as much lift as possible...reducing the density of the local medium (water, or water/air mixture) will reduce drag, but also reduce lift.

Somewhat of a paradox? In short, I'm not a real fan of external ventilation of sponsons or steps.

 

[rippinwater]

I think your idea is a good one, but, you might want to ask yourself if you realy want to drag a scoop through that nice clean air thats passing over your sponsons. I think this might create unwanted drag and possibley unwanted lift on the top of the sponsons. I like the idea of using exhaust pressure to accomplish the same thing, but my version of the exhaust method would take all of the exhaust from the engine and pipin it into integral chambers in the sponsons with numerous holes in the sponson bottoms. Its an idea that came to me when I was trying to think of ways to make my boats quieter and increase performance at the same time. I was sharing this thought with one of the veteren racers in my district and he said, "Just because you can, doesnt mean you should". (as he was shaking his head with a smerk on his face). I wonder if anybody said that to Ed Fisher when he was designing his canard. Hmmmmm. I think that if you dont try it you will never know if it would have worked or not.

 

[Propjockey]

Thanks for the input everybody! I guess it boils down to "try it", huh?

My hydro's not even wet yet, and I'm trying to make it go faster!

Rippinwater--WELCOME ABOARD!

 

[_laxmasta2039]

howdy rippinwater!!

PJ,

that sounds like something to consider trying, though rippin had a good point 'bout the scoop creating drag on a crucial surface. one idea to try would be completely getting rid of the pressure fitting on your pipe, applying pressure to your tank by wrapping a rubber band tightly around it. [this works extremely well, but you just wont be able to use the last .75 oz left in the tank] and then channeleing the fuel directly into the sponsons, either exiting in one large hole or several small.....just be sure to filter it on it's way out, i dont think jetting the old oil out directly into the water's gonna help our 2-strokes survive the ban!! : ;D

also, it might help to squirt the water cooling outlet water down there, but that would probably be more weight/drag on the bottom than it's worth.

joe

joe

 

[Hammerhead]

Think about it this way you guys!

A real tunnel doing 160 miles per hour or a model going 60 miles per hour. If it is 1/12 scale or wha ever, the scale speed of the model is several times faster than the real boat. I don't think that this technology would be of much benifit to the model boat any way you did it. If you design a rigger sponson right, have the balance correct, and the strut at the proper angle, then doing this will be irrelivant.

Just my .02 yen! interesting concept though.

Hammer

 

[_laxmasta2039]

.02 yen hammer?

i jsut plugged that into a currency converter, and it's

0.000166169 US dollars....... guess ya better say "20 yen" or keep your comments short!!!! [lol] ;D ;D

 

[Hammerhead]

Ok Lax! Just my 20yen. By the way, what are the Aussies supposed to say?

Hammer

 

[Ian Inverarity]

Hammer,

With the current value of the Australian Dollar we had better put in at least one dollar's worth! 8)

Ian.