Simple DIY Floats

[jimsp]

DIY floats for your model airplane are very easy and inexpensive to make. No special skills or tools are required and the materials are readily available. Floats are very forgiving so you don’t have to worry about making a perfect set of floats to start enjoying flying off the water.

Recently I posted few threads in Parkflyers (http://www.rcgroups.com/forums/showthread.php?s=&threadid=123956) about making floats for my Slow Stick. I thought I would reorganize the material and post it in this forum trying to make it more general but still geared to parkflyer type models. Over the next several days I plan make a set of floats and show you how I did it. Since there are many good ways to make and mount floats for your model I want encourage input from others. Also don’t hesitate to ask any questions you may have.

The material I present for the most part is not original as I have drawn upon the vast amount of information so kindly posted by others. I will try to do my best to credit those sources.

Tools and Materials

Material
I make my floats out of the inexpensive white sheet insulation (EPS -expanded polystyrene insulation) that you will find at virtually all material supply places and lumber companies. I buy mine at Chase Pitkins a chain in the NE similar to Lowes and Home Depot. A 2’ x 8’ x 2” sheet which is big enough to make about 10pairs of floats cost less than $5. Some places only have it in the 1.5” thickness but that will also work just as well. Occasionally your suppler will have a broken sheet that will be adequate for your needs that they will sell for a few dollars. The rest of the material you need you should be able to find at your LHS or craft supply store.

Cutting The Foam– You don’t need fancy hot wire cutting equipment to make floats!
I use a Scroll Saw(we use to call them jig saws) to cut the foam. A small band saw also would work very well. You could even do a reasonable job using a hand held coping saw. Of course you could also cut the foam using a hot wire.

[jimsp]

FLOAT DESIGN

Float Pattern
The float pattern I use is based on a RCM article written by Chuck Cunningham. You can find a copy of that article here (http://flyinglindy.homestead.com/skisandfloats.html) The dimensions are based on the length of the float which is in turn is determined by the length of the model. Generally the floats should be about 75 – 80% of the fuselage length. For the Slow Stick this worked out to be 25” so that’s how long I made my first set of floats. Later I changed it to 24” because it was easier to simply cut out the starting blanks across the 2’ width of the sheets. My pattern for these floats is shown below. For other size planes you can proportionally change the dimensions based on the float length. In any event don’t worry about getting the dimensions exactly right as anything close should work.
http://www.jimsp.rchomepage.com/core.JPG

Float Width
For lighter planes Cunningham suggested a 2” width but for the Slow Stick I found a slightly wider width worked better. Perhaps the lighter and slower parkflyer types benefit from a slightly wider and shorter float. With the method I am using you can make wide floats even though you’re starting with foam that is only 1.5” or 2” thick.

Float Shape
The floats I will be making a have a pentagon shaped cross-section. They have a shallow “V” for the bottom, sloped sides and a flat top. It’s referred to as the Carl Goldberg shape in this article (http://webhome.idirect.com/%7eironsidz/floatcores.htm) from which I got my inspiration for this design.

[jimsp]

Making the Floats
The first step in making the floats is to cut out starting blanks that are about 2.5” wide by 24” long. Since these are rough cut blanks you can cut them out with most anything.(utility knife, hand saw, hot wire, scroll or band saw) You will need 4 blanks for each set of floats.

Cutting the Pattern
Make a template of the float pattern on a piece of thin cardboard. Pin it to the side of a foam blank and trace around it with a Sharpie type marker. Now using the saw carefully cut out the float. Do this with each of the 4 blanks. Because the foam is very easy to cut you will find you can do a very good job of cutting out these floats.
http://www.jimsp.rchomepage.com/cutpat.JPG

[jimsp]

Creating the Pentagon Shape
In this step you will cut the floats lengthwise so when you reassemble them with the cut faces together you will form the pentagon shape. If you have a saw in which you can tilt the blade or table all you need to is tape down a guide 7/8” from the blade and tilt the blade away from the guide at about a 12 deg angle. With the top of the floats on the saw table cut two of the floats lengthwise starting from the nose end of the float. Cut the remaining two starting from the tail end.

If you can’t tilt your saw like by 40 year old jig saw then you will have to use shims. For 2” thick blanks tape a 1/8” thick piece of wood down on the saw table 7/8” away from the blade. (I angled the guide so the float will clear the arm that supports the blade). For the shim take a 3/8” piece of wood and tape it 1.75” away and parallel to the first piece. (If you are using 1 ½” foam then change the shim to 1/4" and put it 1 3/16" away from the 1/8"guide) Now with the top down and one side resting against 1/8” guide and the top resting on the shim cut two floats lengthwise starting from the nose end and cut the remaining two floats starting from the tail end. The halves you will be using are those that have the wider bottoms. Note the distance of the guide from the blade determines the width of the float. If you increase it by 1/8” the floats will end up about ¼” wider. If you change the distance to the guide still keep the distance between the guide and shim the same.

http://www.jimsp.rchomepage.com/longcut.JPG

Squaring the Top
The next step is to square up the tops of the floats. Tape a ¾” thick piece of wood 3/16” away from the blade. Take the cut halves from above and with the cut face down and the top against the guide, cut along the length of the float to square up the top. You will notice that you will be cutting two from the nose end and two from the tail end.
http://www.jimsp.rchomepage.com/top2.JPG

[jimsp]

Gluing
Now if you cut things correctly when you put the opposite halves together you will have two floats with a nifty looking pentagon cross section. I glued the halves together by spreading a thin layer of Probond polyurethane glue on one half and wetting the other half. I held them together with rubber bands and used pieces of masking tape to keep the rubber bands from digging in to the foam. When gluing make sure the back of the step lines up and that the tops are level. Any mismatches on the bottom are easy to sand off after the glue cures.

Sanding
Sand the float to remove and excess glue and any gross irregularities or mismatches. Don’t get carried away with sanding trying to make everything perfect.

Below is a photo of what the floats look at this point. The pair weighs 1.3 ounces.
http://www.jimsp.rchomepage.com/step1.JPG

At this point you are where you would have been if you had bought ready-made foam cores.
Over the next few days I’ll continue with finishing the floats and attaching them to your model.

[jimsp]

Covering
Covering the bottom of the floats is really a must. It makes the bottom smoother, protects the bottom from small dings and most important it adds considerable strength to the float. The simplest covering is to use 2” wide plastic packaging tape. Just as easy, a little lighter and looks better is to use the colored covering tape they use for covering foam wings. Your LHS will probably have some. Other covering options would be a low temperature iron on covering such as Econokote or Solite. One that is very easy to apply and one of the toughest is 3/4oz fiberglass applied with Minwax Polycrylic. The Polycrylic wets the fiberglass cloth and pulls it down on the foam. Because the cloth is so thin it is easy to apply to a curved surface. With any of the covering options I like to overlap about ¼” on the sides to give the corners of the float some protection. You could cover the whole float but I think this just adds unnecessary weight.

Although not essential you may want to consider gluing a piece of 1/32” ply to the back of the step to give it a little more protection.

I decided to cover mine with the colored tape and the pair now weighs 1.5oz.
http://www.jimsp.rchomepage.com/covered.JPG

[Fredrik W]

It is a honor to be the first one to give you credits for your fantastic efforts! This type of information is invaluable for us water-virgins! :) And I am shure that it takes some serious time to put together.

Keep up the good job! :) It will be interesting to follow.


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

[Ironsides]

Jim:

Wonderful presentation. Great way to make some floats for cottage fun electric flying.

I tried pink/blue foam for my SoarStar floats. I found it easier to sand smooth than the regular white foam. It weighs a bit more, but given the small amount used, the weight penalty was acceptable. SoarStar did not complain.

Look forward to the "mounting" portion.

David

[jimsp]

Attachment
The attachment method I use is shown below. For attachment plates I used 1.5” square pieces of 1/32” ply. They have a 1/8” wide by ½” long slot in the center of them to take ½” x ¾” x 1/8” ply tabs. Use epoxy glue on the attachment plates. Make some shallow holes in the foam under the attachment plates to give the glue a better hold on the foam. Dig out a little area under the slots so you can later insert and glue in the 1/8” tabs.
http://www.jimsp.rchomepage.com/cross.jpg

Plate Location
The plate location will depend on your model. You want to locate the front plate so when the landing gear is inserted in the tab the CG will be at or up to about ½” in front of the step. For example the Slow Stick landing gear lines up with the leading edge of the wing and the CG is about 4 1/8 back from the leading edge. I centered the attachment plate 8 1/4” back from the tip of the float. The step is 12 ¾” from the tip and if you do the math you will see this puts the CG about ½” ahead of the step. Obviously things aren’t actually this precise. I have flown with a range of CG location relative to the step without any problems. Just give it your best guess and it will probably be fine. The back plate should be about 1/3 the length of the float from the front plate but that can be varied to whatever works best for you model.

Cross-Brace
To align the floats, make sure they are level and set the spacing I used ¼” x 3/32” basswood sticks glued to the attachment plates. Spruce would be stronger but slightly heavier. To make sure things were level, flat and square I laid the floats out on a piece of cardboard marked with guide lines. I taped a piece of wood down to align the tips and taped the cross braces in place before gluing them to the floats using epoxy. Finally glue the 1/8” tabs in place after drilling them with the proper size holes for the axle. You probably should coat the wood with something like polycrylic to give it some water protection. The floats now ready to mount on the airplane weigh 2.0oz.
http://www.jimsp.rchomepage.com/glue.JPG
http://www.jimsp.rchomepage.com/done.JPG

[jimsp]

Rigging
The last step is attaching the floats to you airplane. I assume you will be using the landing gear for the front attachment. For the rear support I used 1/16” wire that I shaped similar to the landing gear. To attach the support to the fuselage I bolted and glued it to a piece of 1/16” ply and then attached it to the fuselage using high strength Velcro like material(hook and loop). I got mine at Radio Shack but I have seen it in other places. This stuff holds very well and it is what I use to hold on my camera when doing aerial photography. The adhesive on this material also forms a very high strength bond. This method should work just as well with a conventional fuselage. If you don’t like the Velcro like stuff permanently on the fuselage just put it on a plywood plate and bolt this plate to the fuselage when you want to put on the floats.
http://www.jimsp.rchomepage.com/attach.JPG


I really like this attachment method as it allow some flexibility in the attachment point. Also in a hard landing it will let loose reducing the chance for damage. I confirmed this when I inadvertently landed on shore instead on the water. The rear attachment let loose and nothing was damaged.

Incidence
The key thing about making the rear support is that you make so the wing has a positive incidence relative to the top of the floats. This means you want the front of the wing to be higher from the top of the floats than the back of the wing. Because the Slow Stick wing is positive relative to the fuselage all I tried to do was make the floats parallel to the fusealge. In general I think for parkflyer models the front to back difference should be in the ¼” to ½” range. To facilitate adjusting the incidence you can make the rear tabs a little longer than the ¾” I suggested and drill a vertical series of holes.

Diagonal Brace
You may find that because of the lightweight of the landing gears in parkflyers you will get some vibration when you use them as part of the float rigging. I flew many flights on my Slow Stick without any additional bracing and would occasionally get some vibration in the floats when taking off. Although this never hurt anything I eventually added a diagonal brace(.04”dia) from the top of the rear support to bottom of the landing gear which eliminated the problem.
http://www.jimsp.rchomepage.com/brace.JPG

I still have a few more tips and points to present but you should have enough information now to add floats to your model and start enjoying flying off water.

[Ironsides]

Jim:

Thank you for a great presentation. You have set a very high standard in this forum. A quality act that will be hard to follow.

Might I suggest an alternate method of attaching the floats that might be a bit more rugged?

This method spreads the load a bit more.

David

[jimsp]

Originally posted by Ironsides
...Might I suggest an alternate method of attaching the floats that might be a bit more rugged?

This method spreads the load a bit more.

David
I haven’t had any problems but yours certainly does look simple and rugged. One problem you might run into with this method is that the axle length on some of these parkflyers would be too short. To use this method I would omit the basswood cross braces I used and add a spreader bar that would also be used to extend the axle. This would put the floats further apart but that would be a good thing because it would be helpful in preventing tip-overs when trying to taxi in a cross wind. I have several unused floats lying around so I will give this method a try sometime.

[flipstart]

Jim-great post-I followed your first post in Parkflyers and built several sets of floats for my slow stick that worked great.

To make my floats easy to convert back to wheels, I used your mounting system (the velcro works great), but added X braces of spyder wire with small S hooks instead of the diagonal wire braces, conversion is less than 5 minutes. With the velcro, you can hook up the braces, pull everything tight and press in place for proper alignment. Cut the piece that is glued to the plane a little longer for more adjustment. Flipstart

[Brooks]

Hi, Great thread, thanks! One suggestion: if you run your diagonal brace wire from top of forward strut to bottom of aft strut, it will be in tension when the float hits water, rather than compression. This allows you to use a smaller wire for some weight savings.

[Brooks]

Jimsp, I made a set of TM floats using your design, and they work great. Thanks!

Details, for TMer's, are in the TM floats and tips thread.

[Bill K.]

Thanks for the GREAT thread, I'll be giving this a try this weekend!!!

BK

[Brooks]

Hi Jimsp, your floats work great as ski's; ran my TigerMoth over the snow this afternoon, and it worked great. Such a good float design, thanks!

Brooks

[bmizes]

I made a set of floats for my Slowstick this summer using Jim's design and they worked great. For all of you potential float flyers, here are 2 points I learned this summer:

1. Even if you have a successful landing, you have to be careful when taxiing the plane back to shore. If you turn too quickly and there is a crosswind, the plane will tip, particularly if it has large, undercambered wings like the Slowstick.

2. When you do end up with a plane in the water (and you will at some point), don't forget to bring along your trusty 12 year old and a raft for the inevitable retrieval. My son didn't mind taking the plunge to get my Slowstick as long as the water was warm and the air was not too cold.

Barry

[Brooks]

I hear you, Barry, on the taxi flips :-). Most of John and my wrecks now occur during taxi incidents.

This Fall, I took off in calm winds, but before the Tigermoth made one circuit of the pond, the wind came up with a whoosh. I landed, and because of the strength of the wind, did not even try to taxi turn. I decided to just let the plane drift backwards, planning to pick it up where it came ashore. Well, the wind was so strong, that the plane was drifting backwards as fast as I usually taxi. It was doing fine, leaving a wake and all, for about 100 feet. Then, the stern of one float caught a crab, and the plane flipped over backwards, sort of in slow mo. No harm done, but I discovered yet another new way to crash, hoho.

After retrieving the plane, Jenny and I stayed at the pond to see if the wind would drop (it didn't). Several flocks of Canadian geese landed while we were waiting. With the wind, even they were having problems, and we saw one flock do a go-around, something I had never seen them do before. They all came in high, and to lose altitude, would assume a high angle of attack. You could see the trailing edge feathers on their wings start to ruffle backwards due to the near-stall eddy currents they set up with the high angle of attack, that was cool. Since they were moving so slow into the wind, we had time to really watch their flight manuvers.

My Beaver floats are made from 2" foam, while the Tigermoth's are made from 1.5" foam. When the pond thaws this spring, we will see if the greater depth provides more back-taxi stability :-)

[darkbox]

You mentioned that you also use the SlowStick for aerial photography... Any chance I can get an aerial video flying off of water? That would just make my day... ever since reading this article I've been looking for one. Even just a complete flight video (from land) of the SlowStick flying off water would be dandy.

Thanks

[uniquewon]

You mentioned that you also use the SlowStick for aerial photography... Any chance I can get an aerial video flying off of water? That would just make my day... ever since reading this article I've been looking for one. Even just a complete flight video (from land) of the SlowStick flying off water would be dandy.

Thanks

http://www.rcgroups.com/forums/showthread.php?t=388119

I flew last summer on floats with my SS and took stills and movies. I see the movies in the thread are no longer there, I'll work on that if I can find them, I'll post them here.

CHeck through the thread, I may modify my SS to a puller configuration as someone did and showed in the thread.

Gene

[darkbox]

Alright, thanks for trying to get me those. I'm tempted to build those floats and try flying in our bay (salt water might be a problem). But first I gotta get a replacement elevator servo so that I'm not using servos I borrowed from my car (hehe). Plus, my Rx got rained on, so range is ~100 yards, so that's not a good idea for water.

[Murocflyer]

Very interesting read. Info still good?

Frank

[ty_horn]

Wow, I need to make some of these babies real soon!

[GunnyGlow]

awesome thread! thanks for taking the time to share!! :)

[soco32]

On Sept 3, 2003, JIMSP provided details for building foam floats. I just found his article about 30 days ago and followed his instructions. I had an old E-Flite Apprentice that I had re-powered (more power), so I decided to try his floats on it. What a success! I built the floats 29" long and 3 1/2" wide and they work perfect. The ROW is very realistic - spray blowing back, then the rise onto the step, and finally the lift off. The floats did not detract from the flight characteristics other than the plane is slower. I added a rudder to the left float and drove it with the nose gear, sans wheel. This is a great first float plane because it tracks straight and is very stable. The take offs and landings are picture perfect.

My thanks to JIMSP!

[u2builder]

Our club has a float fly on Oct 10th. I have never flown off water. I think I'll pull my venerable Slow Stick down from the ceiling and build a set of these floats.

[u2builder]

I made up a pair for my Slow Stick. I found a chunk of 2" blue board out in the back yard, kind of dented up, and sawed them out with a small handsaw, and sanded them smooth. I went with the flat bottom style and covered them on all 4 sides with 3M fiberglass reinforced packing tape. Very rugged.

I am wondering if they need a small fin at the back (fixed rudder)?

How do you folks protect the receiver and ESC for float flying on a Slow Stick where they are pretty much exposed?

[AltonMan]

Hello u2builder. I have a slow stick with floats (they are GWS ones I bought at a LHS for $10) I hope it's ok to post in this forum :)

Anyways, I had problems with my slow stick allowing the ESC to get wet. At first I had it near the motor attached with velcro to the stick. The problem is that the weight had to be near the front of the plan in order to get the CG right, so the plane wants to tip nose first into water, immersing the ESC (the motor and battery don't mind water).

So I soldered longer wires to my motor so I could move the ESC back, at first underneath the wing near the back of the wing. This kept the ESC dry if the plane tipped forward, but the ESC got splashed with water on landings - and I had problems with it still.

So...I moved the ESC to the top of the wing. You can see where in this video http://www.youtube.com/watch?v=xG8SEH6LEtI

BTW - My ESC recovered each time from being wet. I took it off the plane and put it in air-conditioning duct over night to dry out.

[lake flyer]

Dunk the Rx and the ESC in corrosion X.

[Brooks]

I waterproofed my esc by filling in the ends of it's shrink wrap with GE Silicon II. That was several years ago, and they may have changed the glue formula. You have to watch out because some silicons give off acetic acid as they cure, and that will attack electronics. I now use "sensor safe" RTV; it does not give off acidic fumes. Be sure to wiggle the wires (protruding from the esc) around to make sure they get wetted with the RTV; probably a good idea to clean them with alcohol first. You can also use a balloon or condom to enclose the esc, rubberbanding the end with the wires; this is more of a splash-resistant fix, not true waterproofing.
------------
I would not use a fixed fin(s) on the end of the float. It creates drag, and if both floats don't have equal drag, then the plane will skew on takeoff. To keep straight, follow real plane procedure: keep the stick back to sink the tails of the floats until you reach float-planeing speed, then ease stick forward to the plane, build some speed, then ease stick back for lift off. By digging the tails of the floats, you make a temporary rudder to help the plane go straight initially. Fins and rudders are useless once you build up speed - they are too effective, and minute deviations from square in their construction will swerve you every time. Take off dead into the wind to reduce swerving.

Most planes need additional tailfin area to offset the area of the floats that is ahead of the cg. You know you need more tailfin if the plane will not quickly weathervane into the wind as it sits on the pond w/ motor off. Look at real float plane pictures to get an idea of where to install and how big. Too big is better than too little. One side benefit, rudder turns (for non-aileron planes) become better with the increase in tailfin area. On my Beaver, the added tailfin is long enough that it drags in the water with stick back, so acts as a rudder for the initial part of the takeoff run. This fin is on the centerline (not on a float), and is under pilot control for takeoff - I can stop it from acting by pushing the stick forward at anytime.

Hope this helps.

[u2builder]

Thanks guys. I think I will try to track down some Corrosion X.

I tried the Slow Stick on the homemade flat bottom version floats illustrated in this thread (no fin) on my little pond and the plane taxied, took off, flew great, looked cool, and came in for a nice landing all on the little 50' long pond. I was amazed it worked so well. It will be fun to fly the Slow Stick again; I haven't flown it much since learning to fly.

BTW, Contrary to some opinions on ailerons for a Slow Stick, I reduced the dihedral to about half, cut out the ailerons along the molded in lines and glued a 5g servo to the bottom of each wing, cranked in max deflection, and find that it flies great with ailerons. I don't know if it is BETTER, but it is definitely not worse, and lets both my thumbs do what they want to do. I was not flying it partly because now that I have learned to fly 4 channel and use the rudder, I didn't want to mess myself up on 3 channel and did not like the feeling of moving the rudder stick when it didn't do anything.