Harry Landings

My Feedback: (8)

Say, is anybody making foam cores for floats. My old link takes me to nowhere. I'd like to find someone who will make floats to my specs, or at least to a custom size.

Dick

arobatx

http://www.foamfloats.com/

http://www.seacommander.com/seafoam.asp

Or make your own:

http://www.seminolerc.com/floatcores.html

http://www.seminolerc.com/EZ-Float-Design.html

http://www.geistware.com/rcmodeling/...oats/index.htm

Harry Landings

My Feedback: (8)

Thanks, Arobatx. That ought to keep me busy.

Dick

Ed_Moorman

My Feedback: (1)

Here are a couple of float likes. I use the Plane Fun Floats on 2 of my planes.

[link=http://www.geocities.com/planefunfloats/]Plane Fun Floats[/link]

[link=http://users.cwnet.com/zdgreg/]John Sullivan Floats[/link]

arobatx

Thanks Ed....Plane Fun Floats is what I was looking for when I was posting all those other links for Harry Landings. Now I can rest my mind on that one.

Walt Thyng

My Feedback: (9)

I'm finally getting around to building some foam floats (I know, I know, it's the end of the season, but maybe I can use them on snow). I checked out all the links above. The most helpful was the Chuck Cunningham article. But I couldn't find anything about float width. Is it TLAR? Relative to the length, height, a/c weight? I've got the foam, the time and the enthusiasm, now I need the width formula.
TIA
Walt

Harry Landings

My Feedback: (8)

I've found a book called R/C Model Aircraft Design by Ancy Lennon. It's not the easiest reading I ever encountered but the part on floats tells how to compute the width.

Dick

Walt Thyng

My Feedback: (9)

Thanks, the Sea Commander site gives the dimensions for all their floats, so I can use them as a guideline.
Walt

JimCasey

My Feedback: (1)

go back and read the Cunningham article again. There is a width table in one of the drawings.

Walt Thyng

My Feedback: (9)

Yeah,
I found it when I down-loaded the original article from one of the links given above. Very close to the Sea Commander numbers.
Thx
Wt

JimCasey

My Feedback: (1)

Calculate the cross-section of the floats you need:

Multiply the width and length and depth of the float together(inches) . multiply by 0.7. Multiply by 0.036 pounds of water per cubic inch . That number should equal or slightly exceed the weight of your plane in pounds. If each float displaces the weight of the plane you have a 100% safety factor. BTW: The 0.7 factor allows for the material removed by tapering the nose of the float, and the volume lost aft of the step.

example. 32 inch floats, 4" wide, 4" deep
32x4x4x.036x.7 = almost 13 pounds water displaced....per float.
considering that 32" floats are used on a .40-sized plane and they usually weigh 6 pounds, this float will either float pretty high or you can cut the float down a bit.

Make it 3 1/2 wide by 3 1/2 deep: you get 9.8 pounds per float
Each float will float 9.8 pounds so you will still have plenty of freeboard and better performance from lighter floats with less frontal area.

This illustrates yet another reason I am not enamored of the big built-up plywood float kits that one can purchase. They are HUGE.

arobatx

I have a float design application that will do the math for you...I found it online. I can email the application to anyone who wants it. I'll likely have to zip it, or rename it based on many email filters out there. I used to have a link to this application online, but can't locate it. If someone wants to look further online for it. The filename is FloatDes by W.H.I.M. If you want me to just email you the file...let me know.

[email protected]

Chad

jmupilot

I built a set of foam-core floats a few years ago, and they still have lots of float left in them. I made them out of the 3/16" paper backed foamcore material. Just used the Cunningham plans and sized them for a 40 size aircraft. Built them just like a balsa set with formers and sides and bottoms. I put a hardwood spline on the top to anchor the landing gear to, and fiberglassed them just like you would a set of balsa floats. I'll try and get a pic of them and post them are on a Midwest Sweet-n-Low and it makes a perfect float set up.

Pete

Newc

Jim - Thanks for that information and basis for calculations. Up to now I have dealt with the old Mark Donohue basis for looking at something - when one is already an engineer, I think - "If it looks right it probably is and if it doesn't it surely isn't." Now I have an even better, more specific, basis for cutting my cores.

FokkerAce

Hi, all.

Have 47-48" pair of floats [kit] that need a new home!!!

pm if you're interested.

FA[8D]

JimCasey

My Feedback: (1)

Careful, Newc. Not that many of us remember Mark Donohue, rest his soul.
I was in College in the days of the Penske "Machine" and saw Mark win Indy.

Newc

Jim - You and I - and 400,000 other close personal friends - were at the Speedway that day. (I started going to the 500 in 1958, and my Dad had been a 500 car sponsor in the 30s and 40s.) I had the distinct pleasure of working with Roger, Mark and the folks at Sunoco on fuels, lubes and some engine issues for a number of years including that year and either side of it and shortly after Mark was killed I was awarded the Mark Donohue Memorial Award when I was driving SCCA Nationals. He was great guy and a great engineer. It showed what kind of person and friend he was that he was killed in F1 after retiring and then coming back to help Roger get their act together for F1.

winglift

My Feedback: (10)

I watched Mark race many times and went to several races and I am sure that I was there when he won the 500.

Try this for float dimensions. From Model Airplane Sept 87'. I am building some floats now. I have not been able to fly or build this summer due to 2 hand surgeries, but now getting back to some building. There seems to be some dispute as to the relative angle between the line of flight which generally is the same as the horizontal stabalizer and the float. Some suggest the stabalizer to have a slight positive angle (1/2 degree) and some 0 degrees. I have also read that some have put in 2 degrees, but that seems to much to me. By adding the extra 1/2 d it will help with the extra drag and weight of the floats. The airplane should generate enough lift at takeoff speed to fly off water.

arobatx

Seems every plane design is different in resepct to float/wing incidence. Most flat bottom trainer type designs get away with 0 degree incidence between floats and wings...my cub's wing is positive 2 degrees as compared to the floats...no re-balancing or trimming of flight surfaces required compared to flying with wheels.

danfarina44

Since you guys are on my subject...Has anyone out there ever built the Float Kit from Sig for the 1/4 Scale piper?

My questions:
1. Do you think my Alpha 60 can handle floats this size? Anybody tried this combination? I have an O.S. 61fx(lots of extra power for regular flying ).

2. Also I am going to be building a 120 size 4* Kit(back ordered) as well. Anyone have any experience with this plane on floats? Are low wing planes better/worse on floats? BTW I think I'll be installing the BCMA 40cc engine, so I know I'll have plenty of power to get me there.
Thanks,

Dan

arobatx

I think the sig 1/4 scale floats would be better suited for your 4*120 than the Alpha 60. The cub floats are designed to carry a plane twice the weight of the Alpha. The cub floats might even be slightly large on the 4*...but you could get away with that long before you could with them installed on the Alpha. Sig makes a 120 class wood float kit...why not go that route for the 4*? The great planes makes 60 sized wood float kits, which would work well for your Alpha. Or better yet...make some foam ones using the information and links provided earlier in this thread.

Chad

jrf

My Feedback: (551)

To answer you basic question, low wings work much better on floats than high wings. On the water, the low wing is much less likely to blow over, and in the air it is better balanced with about half the weight above the wing and half below. Low wings also tend to have more effective air rudders, so you can usually get away with no water rudders.

I recently sold my 4* on floats after 5 years on the water. I used the 60 size Great Planes wood floats but they were MUCH too big and heavy for the 120. My 4* weighed just under 10 pounds on wheels (ST 2300) and the floats added 4 pounds. The 60 size GP floats, like the Sig floats, were designed for their big 15 pound 60 size Cub. My 4* floated like a cork.

www.geocities.com/planefunfloats will be your best bet for both of your planes.

Jim

JimCasey

My Feedback: (1)

To embellish a bit on what jrf said:

High wing planes are easier to blow over. They are also easier to service 'cause you can pop the wing off to get to stuff inside. If a High-wing blows over, it floats on the wing and not much water gets inside...usually just floods the tank compartment. 3-channel planes are REALLY ASKING to be blown over because of the dihedral. A flat wing like on a cub is pretty easy to live with and ailerons help..always taxi holding the upwind wing down with the ailerons, and it's so hard to taxi exactly crosswind you will find that you only go crosswind as you are turning around to take a different heading.

Low wing planes do not blow over quite as easily altho they still will. It's a bit awkward threading the wing in thru the float-mounting struts. You need a cradle to support the fuselage while you service the interior or install the wing. If a Low-wing plane blows over, it floats on the wing, too, which leaves most of your fuselage, radio, servos, battery, switch all submerged.

Anything will blow over when the forces of despair get their way: I have even seen Northstars blow over..and they are almost part of the surface when they are going slowly.

Mount your internal components in the middle of the cavity where sloshing water can just run by them without them sitting in a pool, whether the plane is upright or inverted. The switch should be internal and pushrod-activated so it won't be exposed to spray.

If a plane DOES blow over, pour out the water from the fuse as soon as you can. Remove and dry the foam around your tank and electronics. pull the glo-plug and be sure the water is out of the motor. Start the motor and run it for a while to get the water out of the ball-bearings. Hardened seel bearings like to rust easily. After-run oil is a very good idea here, with corrosionX being choice 1 because you can spray it on your electronics, and Marvel Air-tool oil(MATO) being choice 2. MATO is available at almost any auto parts store, while corrosionX is normally only available at boat dealers. REALLY flood the bearings of a 4-stroke because whatever gets into the crankcase of a 4-stroke tends to stay there. If the bearings rust, a phone call to BOCA BEARINGS for a replacement set of stainless bearings is the way to go.