x3heimmr

I have recently completed the assembly of a Hangar 9 80" Cub and a set of Great Planes 40 size floats. The floats are the built up balsa version. I have trouble with the plane wanting to skip or porpoise just before it is really up to takeoff speed. This is fine as long as there is a little head wind. However when the air is dead calm, the plane skips off the water a few times before takeoff speed is achieved. I have a OS 55 AX in it so the motor will yank the plane off the water, but I don't want that. I want a nice smooth realistic looking take off. This is not the first float plane I have had. I flew my trainer with floats in the early 90's with an OS 40 FP. I have read many many articles and posts about float setup. Right now the floats are at -3 degrees incidence. I am thinking about changing it to -2 degrees. Also the step is too far back I think. Some say to place the step right on or 1/2" behind the CG. I used a rule that says to place the step on a line drawn from the CG at 8 degrees back from vertical. This puts my step at 1 3/8" behind the CG. I am thinking about moving the step forward to ba at 1/2" behind the CG.

My question is this - Will having -3 degrees instead of -2 and having the step 1 3/8" back from the CG cause the proposing I am seeing?

Thanks,
x3

Tommygun

My Feedback: (2)

Do you hold some up elevator during the takeoff run, slowely releasing as you gain speed? Usually I find that gives a smooth takeoff.

Deadeye

Perhaps the step is too far forward?

Sea Commander

xx3heimmr,

The incidence should not effect the plane that much. I think your biggest problem is the step is too far back. Move the step forward so you have it within about 1/2" of the CG and I would bet your problem will be solved.

Hope this works for ya[8D]

evan-RCU

Step too far back or the area behind the step is to long.

simhatus

Hi

yes it will.

put the step on or slightly behind the cg. set the incidence as suggested, change it if needed, with aCcub you shouldn't need to.

Simon

Falcon6667

Watch the plane as soon as it rotates forward, back off on the power. Think about it the plane is nearly flying at that point, so tease a little of up elevator. Same on landing as it comes close to water add power you'll love the "look".Water flying (as far as i am concerned)is all about the take off an landing. Once in the air flying is flying.
Falcon

mintie

I have just put my Super cub on floats..The step is 1/2 in behind the c.g and the wing incidence same as yours and this works absoluetly fine. On take off I hold back on the stick to keep the nose out of the water and so as a bit of speed is up, release to neutral and let the speed build up for take off. No other inputs are required and it will lift off by its self. Just on lift off the floats are right on the step and the rear you can see light under.Very little spray at this stage.Landing just as much fun ,fly right onto the water. Dont give up its addictive.

x3heimmr

I'm not giving up by any means. This plane is dedicated to float flying only. I just want to get it to that "Hands Off" take off. Right now, I have to take off prematurely to prevent the porpoising. I go camping on the Ohio River about 20 weekends a year. This plane will live at the camp and probably never see my local club's filed again. My intentions based on all of the advice so far is to move the step forward to 1/2" behind CG and change the incidence to -2 degreees. I have more than -2 degrees righs now. I'll post again once we have a flight or two with the changes.
Thanks,
x3

mintie

Hi x3heimmr.....If it is of any help to you.will give you the info how I set mine up.....I placed the floats on the work bench and set the float tops at 0 deg.I then put the meter on the tail plane and set that at 0 degs.This is with the plane sitting on the floats in the correct positon,and the front mounts scewed down and the step in the correct postion. [1/2 in behind c/g]Then put the meter on the main wings and the leading edge to trailing edge measurement was 3 degs. pos. That is how my super cub flys.. good luck with yours. I am now building two more float planes......cheers mintie.

Augie11

The information you've gotten on the incidence and step position should help you out. As an aside, I had a similar setup for years and it worked ok but when I decided to replace that well-worn bird I went with the 80" GP Arf and built a set of their '.60 size floats'. A little heavy but I've got an OS .91FS on her. Even built a Midwest canoe and lashed it to the floats. At any rate, this newer setup takes off beautifully no porpoising or 'water loops', wings level and no tendency to snap. Makes me look good! Just a suggestion to keep in mind.

Augie

x3heimmr

I set mine up a similar way on a table. I set the top of the floats level and measured the incidence on the wing. After more thought, I believe I'll leave the float incidence at -3 degrees compared to the wing and just move the step foreward. I have not heard of anyone else with the step as far back as I have it. I'll keep it simple and only change one thing at a time. Mintie - your Cub looks great!
Thanks,
x3

mintie

Thanks x3...thats the way one change at a time. keep us posted on progress. cheers mintie