CG and Step

[jimsp]

I’m posting this in a thread separate from by DIY float thread because regardless of your mounting system or float source you will want to check the step relative to the CG. An easy way to do this is to set the plane ready to fly on a flat surface and see if it will rest both tipped forward and tipped backwards on the floats. If it does you know the CG must be located roughly over the step. Although I flown very successfully when the plane rested only tipped back and only tipped forward I think the intermediate position is best. Below shows this for the set of floats I just made for my Slow Stick.
http://home.stny.rr.com/jimsp/Floats/front.JPG
http://home.stny.rr.com/jimsp/Floats/back.JPG

Alignment
This is also a good way to see if you’ve done a good job mounting your floats. When tipped back both of the backs of the floats should touch the surface. If they don’t adjust your mounting system or bend the landing gear or rear support to correct the problem.

[jrsnow]

Got my Lite Stik floats from Climate Models in Canada. Their instructions say the step should be directly under the CG or 1/2" behind. Flew mine over grass with the CG slightly forward of the step. Flew okay and landed on grass better than wheels. Have shipping tape on bottom of floats.

[Ironsides]

Your floats will work well in Michigan powder snow. Better than skis.

David

[T. Lyttle]

For freeflight, we usually had the step ahead of the CG, but having elevator capability changes everything, of course. Nothing like watching a Berkeley Sea Cat leaving a lake; oh dear...

[Fredrik W]

Some say that C/G should be behind the step, some say on the step and some in front of the step.

Basically, i think that it does not matter. Think that the planes angle of attack in relation to the floats is more important.


// Fredrik Wergeland
Sweden
www.flyingmodels.org (http://www.flyingmodels.org)
The Great Electric Motor Test (http://www.flyingmodels.org/motortest/Link_e.htm)

[T. Lyttle]

Exactly right for radio, but f/f meant that you needed the drag of the rear of the floats for it to track straight, otherwise all you got was a series of waterloops (?). Once you add radio it all changes, but being a mediocre pilot I need all the help I can get, particularly on takeoff!