goirish

Need Help!! Tried flying my DeHavilland Beaver and I couldn't get it to break loose from the water. It would get up the step quite quickly and seemed to have enough speed to fly. When the elevator was pulled up the tail would drop and create a quite of drag. It weighs 10lbs 8oz and is powered by a magnum GP65 swinging a ll-7 prop. It looked like a hydr-plane skimming across the water but like I say it never broke loose. Any suggestion will be appreciated.

goirish

What should the datum line on the fuselage be in comparison to the top of the floats. Should it be a positive number?

arobatx

Flying off glass like water can also be 'sticky' compared to some ripple. If you check your wing to float incidence, typically, you should have a couple degrees of positive incidence in the wing, when the float is level. This will aid in leaving the water. If you go more than 2-1/2 degrees, things could become more tricky at landing, so try using the smallest amount of positive incidence needed.

So measure your incidence with the floats and wing....not the fuse!!!

Chad

HUNTERANDJEFF

Nice looking plane Goirish. I am asuming that the beav. in the pics is yours. Who makes It? What engine is it again? is it a fourstroke .65? If that is the case you may be a bit underpowered for the weight. It also looks like your floats are a bit too far back. When I set my floats on a new plane I first balance the plane. Then, I tape the floats to the fuse and balance the plane and adjust the floats to the balance. If everything works out right and you have the right floats (size) it should sit just a bit positive in the water. I also like to have about two degrees positive incidence from fuse to float. On my last plane, I had problems with getting it off of the water when the surface was glass (it too was a bit underpowered) so I did a bunch of circles to make the water choppy and then backed up ran through the ripples and whala! I was off!!!

Hope this helps and not hinders

Jeff

HUNTERANDJEFF

Nice looking plane Goirish. I am asuming that the beav. in the pics is yours. Who makes It? What engine is it again? is it a fourstroke .65? If that is the case you may be a bit underpowered for the weight. It also looks like your floats are a bit too far back. When I set my floats on a new plane I first balance the plane. Then, I tape the floats to the fuse and balance the plane and adjust the floats to the balance. If everything works out right and you have the right floats (size) it should sit just a bit positive in the water. I also like to have about two degrees positive incidence from fuse to float. On my last plane, I had problems with getting it off of the water when the surface was glass (it too was a bit underpowered) so I did a bunch of circles to make the water choppy and then backed up ran through the ripples and whala! I was off!!!

Hope this helps and not hinders

Jeff

flynfish44

I must agree with the statement about the calmness of the water. Full scale float planes will circle around the take off area to create ripples helping to break the surface tension. Also, making sure you are taking off directly into the wind helps. Just a little sideways to the wind or even down wind will hamper the ability to rotate and climb out.
Your statement about pulling up on the elevator may also be the problem. Too much elevator will make the rear of the floats dig into the water causing more drag. I suspect you have one or two problems. Not enough incidence between the wing and top of the floats or you are slightly underpowered. When I want to taxi at high speed I give the plane full up elevator to make the plane " mush " , very nose high attitude. This creates a lot of drag and I can taxi very fast without a fear of taking off.
Try getting her up on step again and feed in some elevator a little at a time and see what she does. Good luck

goirish

The lake was like glass. It is a scratch built beaver--74" W.S. Powered by a Magnum GP65 swinging a 11/7 prop. When I brought it home and checked the incidence it was at 0' maybe -1. I have lifted the front landing gear strut by 1/4" This gives me a +2' at the leading edge. The floats are set with the step approximately in the middle of the wing. I know that we were trying to give it full up and it just would dig in at the back. Will try to ease it off the water next time. It appeared to have enough speed to fly.

goirish

Sorry no wind at all--dead calm

arobatx

The step should be at or slightly behind (1/2") the CG. You'll want to confirm the before and after float install CG as well, making sure it is the same after installing the floats.

aerowoof

Did you have a successful flight yesterday?

JimCasey

My Feedback: (1)

Put about a 3/8" shim under the forward float mount. When you made your floats did you make the step sharp or did you round it off when you sanded it? (sharp is the right answer).

Three things cause the inability to break suction on glassy water: one is rounded step, the other two are sucky float installation. Get your floats rigged properly and the problems go away. Ripples don't break suction, they just bounce your plane up so it can rotate to a positive incidence. you need Slight positive wing angle, floats parallel, step at 40% of chord, kickup water rudder. TaDaaa! flight happens.

Good luck.