hydroplane handling issues ??

[afrhydro]

ok i hope i can explain this so you understand what I'm talking about
not every time but some times i dont know why
after you get up to speed
see video below

the boat drifts left then right back and forth i always just get off the gas
i posted a video of another boat doing the same thing and he just drives threw it
is there away the fix this


http://dragboatracing.com/Media/Vide...Child-TFH.aspx

[eponodyne]

Do you have air traps installed?

[afrhydro]

i just installed a set but have not tried it yet
plus i re aranged all my weight more forward now as well
maybe it wont do it now
ill have to find out
but i was just asking what would or could cause it

[Ike]

You have to remember that a hydroplane, whether a three point, or pickle fork (from the video it's hard to tell but it looks like a pickle fork) is not really a boat, it's a low flying aircraft that touches the water at a few places on the hull. So the laws of aerodynamics are more important at speed than hydrodynamics. You have a wing forward. That wing is supposed to keep the bow down. But since the bow goes way up at startup you are making a big change in the angle of attack and creating lift instead of downthrust. I don't know what the rest of the boat looks like, but you haven't said anything about steering and rudder size, and how much of the stern is in the water. All these things effect your steering. Hydroplanes should never have more than a degree or two angle of attack when at speed. Otherwise they kite, that is take off and fly. Which is what appears to be happening in the video. It seems to be on the verge of taking off. Unfortunately they don't fly well. So you need to look at how high the bow is flying and how much rudder surface is actually in the water, plus how much slack is in the steering. There should be none.

Back to the canard (the wing at the front), some of the unlimited hydroplanes use an adjustable wing that changes angle as the bow rises to get the bow back down. But it's not manual it's down by a computer.

Just some thoughts.

[afrhydro]

i been wanting to put two canards on this since i built it
front and rear and try to fly it
here is a mix of pictures
some old some new
i have moved the cockpit forward added air traps and transome wedges like trim tabs kinda
it has always run as a tail dragger so far
i have blown the tail a few times and that when the steering issues really show up
its a prototype that i designed and built and still a work in progress

[afrhydro]

i think i see it
the pad on the sponson needs to be fatter

[Ike]

Also, you might want to think about adding a small fin on the inboard side if each sponson. It doesn't have to be real big, just maybe six inches long by six deep, triangular. Just something to keep it going in straight line. Since it's a drag boat, you don't have to worry about going around the buoys so this won't affect turning ability.

[afrhydro]

i like your thinking
Don't tell me that I can't. Tell me how I can!"

yea i have a set of fins made up but i never put them on yet
cause we just cruising around most of the time
just hit it for short burst from time to time