Float design
 

I'm trying to design a set of floats for the aircraft that i'm building and would like any comments or suggestions regarding the floats pictured before i commit to building.
Any foreseeable handling problems on the water? The floats have a small deep v section running down the middle of the forward section with a
step on either side to hopefully direct spray outward instead of upward onto the plane. The aft section has a regualr v profile.

RE: Float design
 

goose:

The flat section in the front does not have to be that wide. 1/4" will do. Also the very deep "V" in the front will act like a keel and make the airplane harder to steer on the water. If you use the same overall profile but make the "V" shallower and the flat section narrower, your floats will ride softer and steer better without loosing any floatation or spray protection.

Jim

RE: Float design
 

I tend to agree with JRF.

The sharp keel at the nose might grab a wave if you have any crab angle going. It would make for a short, splashy landing. I suspect you might also find that the step is a little small, and you could have trouble breaking suction. Also with the changing V-angle all along the bottom, it'll be a lot more difficult to build these than it needs to be. But they DO look really cool.

You >>Could<< make the v-bottom angle constant. For arguement, let's say 20 degrees. Then glue some triangle stock at the outside edge as spray deflectors/chines. It would look almost the same when finished, but be easier to build.

RE: Float design
 

That was my concern, the sharp keel making it hard to turn when taxing or a float really grabing especially when one float is out of the water and one is still in.
I was hoping the only thing it would do was make the plane a little harder to turn. I wonder if i was just to sand and round off the keel. These will be going on an original unproven
airplane design. I definetly don't want the floats to be causing me alot of grief before i know the thing flys.

RE: Float design
 

I remember from high school something called "The Scientific Method". Only change one variable at a time.
If you have an unproven plane, it would be prudent to use a proven float design.

I usually post a link to Randy Linderman's website when somebody asks about float design, but I already gave you that.
Here's another link with Ed Westwood's article from Model Airplane News. Ed Westwood also designed the BEAST from RnZ models, and RnZ also sells John Sullivan floats which are widely regarded as good. Round on top, flat bottom.

http://users.rcn.com/llfc/floats/

RE: Float design
 

Ed Westwood also designed the 2 Ugly. Plans for it are available from Model Airplane News. You can find it in the Jan issue that has the plans catalog. Both it and the Beast use a reflex airfoil similar to the one Bill Evans used on the Scimitar series.

RE: Float design
 

Thanks for the replys, that was alot of good information. I've decided to keep the same shape looking fom the side but alter the bottom to mostly a very shallow v with it deepening a little near the tip.

RE: Float design
 

Much better.

If the prop gets spray, you can always add spray rails.

You might want to square off the transom if you intend to mount water rudders. The Tapered transom LOOKS slick, but it's hard to fab a clean water rudder mount that way.

RE: Float design
 

I'll keep the transom angled because I rarely ever use water rudders on my float planes anyways and i think the angled transom really looks good on the plane.
This is the plane here. wish i had a digital camera so i could post a pic of it all fleshed out with balsa and ply, still have to build the wings, cowl and floats. Should be ready
by the time the ice leaves the lakes for its maiden flight.

RE: Float design
 

COOL!!

I like the vert stabs on the floats. I have always wondered why more planes dd not have that.

RE: Float design
 

Sharp looking plane.

RE: Float design
 

Thanks, I'm building this first one at 3/4 the size as what i drew on the plans. should be a good 40 size plane.
52" span
540 " wing area
40" long
32" floats
if this smaller version flies good I might build the bigger 90-120 size one, or get to work
on drawing plans for the plane in my avatar.

RE: Float design
 

I agree, that is a great looking plane.

Vertical stabs on the floats are not used because their moment arm is so short that they are only 40-50% as efficient as the same area (and presumably weight) added at the rear of the fuselage. You have plenty of side area in the tail without them so they probably aren't needed, but on the other hand, they probably won't hurt anything and if you like them....

The size you have given is quite small to carry the added weight of the floats. I'd watch the wing loading.

Jim

RE: Float design
 

I know it will probably weigh more than most other planes with the same wing area because there is quite a bit more wood in the fuse. Not counting the tail post or firewall there's 8 formers in between, and a box crutch running down the center, but i've used lightning holes and have been choosing my wood carefully. Hopefully the weight is no more than 6 pounds with floats, otherwise i might have to stick my Saito 80 in the nose instead of the Magnum fs 52 i just bought for it. I'm sure i can keep the floats themselves to about a pound.

RE: Float design
 

Isn't that step forward of the CG ?

RE: Float design
 

I'll put the step right at the CG, it does look like its forward of it alittle in the pic.

RE: Float design
 

Hello

Could anyone please direct me to a website, where I can find some plans that I could download to build floats.

I have never built, yet flown a float plane, but would love to start.

Many thanks

Richard Clausen

RE: Float design
 

This is the beat place to start:
http://www.flyinglindy.homestead.com/skisandfloats.html

Here's another: http://users.rcn.com/llfc/floats/

RE: Float design
 

Here's some pics of the almost finished floats that were the reason i started this thread. I kept the angled transom. i just finished glassing the bottoms today. The top and sides are next.