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Aug 22, 2019, 01:23 PM
Registered User
Thread OP
Question

Do These Floats Look Right to You?


Hi all,
Hoping for some input from experienced float plane flyers.
First time trying to fly off the water using (Great Planes 60 size) floats purchased about 5 years ago, maybe longer. Finally decided to put them on my Nor-cal BT 13. After watching many videos and pictures of floats in general, I'm thinking mine look to parallel to the ocean. I understand it was choppy when I attempted my taxi test but curious as to what some experienced float plane flyers think. This is how it sits after I've balanced it with floats attached. I had to add some weight to the nose of the plane beforehand. I'm now wondering if I should remove some just so the float tips sit a slight bit higher and thus the floats will not look so parallel to the water. And since I'll be flying on salt water, I surely would not like the float tips to dive in and tip the plane over. As that would be the end of all electronics and lipos.
Any thoughts, suggestions? Or does it look right to you?
Sorry for the long story.
Thanks.

Video is here:
Bt 13 video for RC Groups 2 (1 min 10 sec)
Last edited by seair; Aug 22, 2019 at 01:27 PM. Reason: Thought that the URL option would show where to find my youtube video
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Aug 23, 2019, 11:05 AM
Registered User
My observations from the video, based on 35 years of model airplane float flying and at least a hundred seaplanes and float planes:

The floats seem to ride very low in the water. They may be too small, or the airplane is too heavy for them.
You don't have enough float in front of the prop. You should have a length of float of about half of the prop diameter extending in front of the prop.
The nose of the floats seems too low (too much negative incidence). Floats on a model airplane work best if the top of the float is parallel to the datum line of the fuselage (usually the same as the top of the stabilizer.)

The combination of these things leads me to believe that you are very likely to nose over on takeoff.

Jim
Aug 23, 2019, 04:52 PM
Registered User
Thread OP
Thanks a lot Jim.
Well explained, and much appreciated.
Aug 24, 2019, 11:57 AM
A man with a plan
Balsaworkbench's Avatar
You mentioned the possibility of removing the weight that you added, but you have to maintain the airplane's correct center of gravity for flight. You can't use the weight to adjust the way the plane sits in the water.
Aug 30, 2019, 01:18 PM
DHG
DHG
Kinetic Sculptor
Quote:
Originally Posted by Balsaworkbench
You mentioned the possibility of removing the weight that you added, but you have to maintain the airplane's correct center of gravity for flight. You can't use the weight to adjust the way the plane sits in the water.
+1

Yes, the solution may be to simply move them forward a couple of inches—provided that doesn't put the step too far ahead of the CG. Ideally you want the step pretty close to the CG; think of it as analogous to the main struts on a trike-gear airplane. If it's too far back, the airplane won't be able to rotate easily for takeoff, and if it's too far forward, the airplane will wallow tail-down.

It does look like the noses are digging in right now. That may change if you alter the position and angle as suggested in previous posts, but if not, the floats are simply not buoyant enough for the airplane.

That's my .02 ... no refund without receipt.

Cheers,
Duane


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