This is my first float plane, after getting into and flying RC for three years. It's a Hobbico Superstar ARF 40 with Great Planes J3 Cub ARF floats, powered by a Tower 46. I found lots of useful suggestions in this forum, and after about a dozen flights on this bird here are some conclusions:

1. Waterproof servos are not. Tracking down and blocking every source of water entry is a MUST. Most of the "debugging" I've had to do involved servos that died due to water penetration. The most common failure mode was "trim drift", followed by either full travel in one direction or complete unresponsiveness. I tried the HiTec HS-5645MG servos, which are advertised as waterproof, and they are NOT. To prevent water entry, I pack the end of each pushrod tube with Vaseline before flight. I've used RTV in the wing saddle, but it's not enough by itself. I put a layer of Vaseline on the RTV, put the wing rubberbands on, then use colored packing tape as a further barrier under the wing on the saddle joint. This works 100%.

2. I set the wing - float incidence at about 1 degree positive for the wing. This seems to work well as long as the CG is about 1/4-1/2" aft of the steps on the floats. If the CG gets too far forward, the plane tends to bounce a lot on takeoff. I ended up with the CG about 1/8 of inch forward of the forward most point recommended by Hobbico.

3. I used two servos for rudder- one water, one air. They are both in the fuse, and the water rudder flexible pushrod assembly runs from the right side of the fuse to the float, where it is held in place with epoxy.

4. Lots of power is a must. The Tower is a strong 46, but I wouldn't want anything less. The high lift wing of the SuperStar helps a lot. The airplane handles well and is fairly responsive even with all the extra weight. (The floats weigh almost as much as the airplane.) Always, always, warm the engine up completely, shut it down and refuel before attempting a flight. This minimizes flameouts.

5. The water handling with this combination is SUPERB. (The GP floats have a huge water rudder.) I tried a Lanier SeaBird last year, and never flew it because it STUNK on the water. This one goes where I point it and has no tendency to nose over or flip over in a crosswind.

6. Takeoffs are straighforward as long as you always go into the wind. Don't even consider taking off in any other direction. Full throttle, full up elevator until she gets some speed, then relax and steer. When she's hauling, start applying backpressure until lift off.

7. Landings: Start downwind at about 100 feet or so altitude, throttle back to idle and set up a slightly nose down glide. Maintain this all the way through base onto final. The turn on to final will be at about 50 feet altitude. Throttle up to just over idle and establish a level attitude. The bird will sink. When within 10-15 of the water, throttle back to slow idle and flare, flare, flare. A nice slow touchdown with the nose high gives a sweet landing every time, and crosswinds are not a problem as long as you keep the wings level. Any faster, and it skips like a flat rock. In order to get nice landings, I find that I must have the bird crossing in front of me, L-R or R-L, and try to set up the touchdown point directly in front of me so I can see it well. Any other way doesn't work well because it is very difficult to judge the airplane's attitude as well as it's height above the water.

Your landings are great, let us know when you dig the tips of the floats and flip it over. I am not trying to be sarcastic but it will happen. I learned the hard way. A little power in and a little speed until touch down is much safer. The water is such a huge friction source htat the plane will slow fast enough if you come in a little faster. Like I said, I found out the hard way. I had been priding myself on these beautiful slow and gracefull landins. Every one told me to power in and I thought I was just great and had it all under control until I put one over. Not once but twice. A little power in and I have never flipped again.

Here are a few of my birds.

You mean like this?

I have a few acro planes on floats, but a buddy gave me this World Models Sky Raider trainer and told me to put floats on it. No problem with a trainer, right. I used Niagara foam core floats http://www.foamcorefloats.com/. The first few flights were great with a Mag .52 4-stroke in the Raider. The second weekend, the wind came up slightly. Believe me, you need to "fly" the plane all the way to the beach or this will happen. High wing planes, especially those with dihedral are bad for flipping.

SFCBHunt, could you post some pics of how you've got the water rudder servo installed and the control rods and all mounted. I'd like to do something similar to what you're talking about, but it's easier to visualize with actual images in front of me. :-) Thanks!

Dave:

I agree with you about the possiblity of digging the float tips in. I could definitely see it happening if I let the airspeed get too low, and run out of elevator close to the water. I'll be careful, I promise.

Bob Hunt
Cadillac, Michigan

PS Sure am having fun with it.

Ed:

I've been purposely avoiding any kind of high winds and/or wave action. Even with 3.5 pounds of floats hangin under a 5.5 pund airplane, I can see something like that happening. Remember: aileron into the wind during taxi. Works on full size, should work on ours.

Bob Hunt
Cadillac, Michigan

J:

Sorry this took so long. I'm had trouble figuring out exactly how this forum stuff works.

The pic shows the right side of the plane. I put the water rudder servo into the hole where the throttle servo would have gone, and ran the flexible pushrod out the right side of the fuse. I secured it and sealed the opening with 5 minute Epoxy. The tube (red) is held down to the top of the float with a couple puddles of the same stuff. (I believe in fast, simple, durable approaches to problems. Drilling holes in floats for screws doesn't fall under that description. )

Bob Hunt
Cadillac, Michigan

Okay guys, I'm going to throw a few different kind of questions at you. I'm just about to start building a modified Sig Kadet Jr, and need some input from those who have been there. I'm looking at modifying the wings by removing the 1.75" dihedral, adding 3" per wing for a total span of 54", adding 2.5X8" ailerons and flaps from the ailerons to just short of the cabin. I'm also lengthening the horizontal stab by one or two inches at the advise of a master pilot/builder. My questions are simple:
1) The plane is designed for a .15 to .25 and I have an O.S. Max .25 FP. Will this be enough power to get the plane off the water, or should I look at more like a .40?
2) Are the flaps I'm looking at adding something that will help or hinder take offs and landings?
3) I'm looking at getting a Futaba 9C, which has mixing abilities. Would it be worth while to program in flap functions for the ailerons?
That's all of them(for now), so give me HONEST OPINIONS WITHOUT CANDY COATING ANYTHING. I'm still at the point where changes can be made, so...................................

Is the Kadet Jr similar to the Senorita? If so, it looks like it has a lot of wing for it's weight. Starting with a low wing loading initially is important when adding floats. With floats, mine came out close to 30 ounces per square foot. That means stalling speed is somewhere in the vicinity of 24mph at sea level. Assuming the structure is strong enough, it should make a good float plane. I think a strong .25 would work fine, if that's the largest engine recommended. Don't get too slow on approach, and keep the nose DOWN until you're close enough to either flare or set it down.

Flaps, I dunno. Extra weight for not a lot of benefit, and the added risk of the bird popping off the water before she's really ready to fly. Unless you have a long run of unobstructed beach to fly from, you'll find that the plane will always be far enough away from you that seeing it well and trying to judge accurately what it's doing become difficult. Anything, like flaps, that adds wrinkles will just make it more difficult.

Mine was an arf, and I didn't feel like recovering it for better visibility. I should have. If you haven't covered yours yet, I suggest Coverite neon red on the top and sides(including the fin), and black or very dark blue for the bottom. If you're covering the floats, make their tops and sides neon red, and the bottoms black. The Coverite neon red comes out as an incredibly bright orange and makes it super easy to see even small airplanes. I used this combo on a 40 Shrike, and it really works.

The GP ARF floats I used were intended for a much larger Cub, in the 9.5 pound range. My whole airplane with 3 pound floats only weighs about 8.5 pounds. I think having the floats so big really paid off. It's no aerobat, but the water handling is great with no tendencies to plow under, flip, etc, and if I do a crumby landing it just bounces back up in the air. The ARF floats came with a lower fin assembly that I used to get extra vertical stab area. You might want to consider that and leave your stock fin as is. It was basically a piece of lightened 1/4" balsa, covered. GP had this fancy mounting system that allowed it to be removed from the airplane easily. Just gluing it to the bottom and strengthening it with a couple pieces of triangle stock would work as well.

Make sure to mount your floats so that your CG ends up in the general vicinity of the steps, and mount them so that the bottom of the wing is at 1-2 degrees positive incidence compared to the flat top of the floats. It seems to me that the plane lifts off the water cleaner if the C.G. is at or slightly behind the steps, but I'm not real sure about that. Still playing. I only have about 1 degree positive incidence, and wish I had a little more. (It takes a fair amount of back stick to get my bird off the water. More than I like.)

Water is your enemy. Use rubber gaskets (RTV works good), backed up by a thick layer of Vaseline at the wing saddle, backed up with a layer of colored packing tape over the wing/saddle joint, top and bottom. Use sealed pushrods, or pack the ends of the tubes with vaseline, or both. Before putting control horns on the servos, gob vaseline around the tops of the shafts where they come out of the servo. One drop of water inside a standard servo will make it go whacky. I nearly lost my plane four times due to this. (I've had more good luck than I deserve.)

Hope this helps.

Bob Hunt
Cadillac, MI

Forgot about this: I think taking the dihedral out is a good idea. I have so much (factory) that the airplane turns best using rudder into the turn, and opposite aileron to prevent overbanking.

Here you go with no candy coating:

Mods are fine and should work nice. The flaps won't be necessary, but they should be fun to play with.

.25 FP will be perfect as long as you keep the plane LIGHT. If you do not keep the plane light then you will need more power which ends up with more weight and you are in a death spiral resulting in a lead sled plane that flys like crud. Keep it light! Don't use a .40.I

Get and use the nice radio. You won't regret it.

I don't know which floats you are intending to use on this plane, but I would highly recommend floats made from white styrofoam. It is easy to cut and make your own if you cant find some commercially made from this material. This is the lightest option.

Jeff

SFC, as compared to the Seniorita, the Jr is about the same size, but with a 48" span instead of the 60"(?). It's also slab sided with 3/32 balsa instead of stick and covering. I was looking at that 1.75" dihedral and just couldn't justify it, so....................................... What I have also been told by designer/builder/pilot Dave Robelen is to have the step SLIGHTLY BEHIND the CG and have the floats 75% of the aircraft length, or in this case, 27".

Goinstraightup, is there any other way to build a plane besides light? With my modifications I'm looking at , I had TWO MAIN CONCERNS: WING LOADING AND LANDING SPEED. That's why I'm extending the wingspan 6". It's also the reason I'm looking at flaps. Call it crazy, but I'm thinking shorter take off runs and slower approach speeds to minimize the stress of running across water. As far as a radio, I don't think I can get much better than the Futaba 9C. It's fully programmable, has multiple model memories, is FM/PCM and can be used for either aircraft or cars/boats. What more can you ask for in a 9 channel radio?
I found a set of plans for a .25 sized F4F-3 Wildcatfish, including floats, so I was thinking about building them for my bird. I don't really trust the white foam, as I've seen it soak up water and knowing how fragile it is, I think I would rather work with balsa, lite ply and aircraft grade ply, another reason for the extended wings I've download the plans from the Wildcatfish so you can get an idea of what I'm looking at for floats. Who knows, it might be my next project

Hydro,

Yes, there's many ways to build other than light. I over built my planes for years until I rebuilt a .25 size plane doing everything to save weight. The first plane was powered by a .40 engine. The 2nd plane was powered by a light and powerful .25 with some mods and like I said EVERYTHING possible was done to save weight - construction / equipment... everything. The 2nd plane was 9 oz lighter than the first one. The difference between the way the two planes flew was night and day. The light one flew 1000000 times better than the heavy one, even though the heavy one had more power, the weight to overcome made it fly like crud.

Your float length and step location are correct. I went to give you the link to the Chuck Cunningham float design standards, but the site was down. I'll keep checking. There's lots of float design threads here in the Float flying forum. You're on the right track.

For the reasons in my first paragraph above I would HIGHLY.... ABSOLUTELY recommend against built up floats for your plane. Your comment about White foam soaking up water is so mind boggling that we must be talking about something different. I've never ever saw closed cell white styrofoam soak up water...it's impossible. The material you saw soak up water must have been something else. I've used built up floats and home made styrofoam floats on floatplanes. I used styrofoam floats on a Kadet MKII for 3 years that worked excellent and were only covered with packaging tape. Yes they looked like crud, but were functional, super light, and never soaked up any water. Yes built up floats look nice, but are waaaayyyyy heavier. Look at the example above in this thread....3 pounds!?!?!?!! Thats over half of the plane weight! My styro floats for a .40 size bird are a half pound. That's with all the supports and everything. Even if you glass them (which I would recommend) you are still under a pound.

I like working with balsa and ply too, but for your application foam is the only way.

Jeff

Here are the Cunningham float design standards.

Bob

If you can't make the above out, try this.

Bob

The white foam I'm refering to is like the molded packing material. What I saw was used for floatation in a boat. After a flip, the boat sank(not enough floatation) in shallow water, so it was easily retrieved. When the foam was pulled out, the owner was able to get water out by squeezing like a sponge. It also quickly crumbled as he was pulling it out of the boat. If I do foam floats, it would be using the pink or blue insulation foam from the local home center. That stuff is almost indestructable[8D]

The pink and blue (color depending on manufacturer) foam is the extruded type and can be sanded without breaking apart as the white (expanded) type does when trying to sand. The extruded is heavier. This fuselage is made from extruded foam.

White foam CAN absorb a small amount of water. This can happen if you leave it submerged for an extended period of time. Don't do that. Take your airplane out of the water when you are done flying, and store it out of the water. However, it has never been documented where white foam absorbed so much water it would not float.

Built-up floats CAN absorb a LARGE amount of water. This can happen if you hit a stick on takeoff or landing. If you hit the stick just right, your float can be full of water in 0.00000263 seconds and you will wonder why your airplane mysteriously just disappeared. Or, if you actually take off, the plane will swap ends as soon as the water runs to the rear of the floats. This will lead to a curtailment of your day's flying activities and an airplane-sized debit against your Visa Card, if you're lucky. You COULD lose your engine and radio too. Built-up floats can also absorb a teaspoon of water, which is enough to feed massive amounts of ROT. If the balsa rots off of foam floats, they still work. If the wood rots in built-up floats, you get to hire a diver to look for your motor.

White foam floats are NOT fragile. I have an old set of white foam floats that have been on at least 5 planes. 2 big Lazy Bees, a Stik, a FunFly, and a SPAD. SOme of the planes have had the floats on and off several times. They are balsa sheeted and covered with film, They have been patched and fixed and are tattered, but still serviceable. However, I could break one in half and the pieces would still float, and I could glue the pieces back together and be flying the next weekend.

With foam floats, I boneheaded my plane into granite riprap and holed the balsa bottom. Went out, grabbed the plane, dried the floats, slapped on some packing tape, and kept flying, as has been documented in threads in this forum.

Pink, blue, and gray foam are OK for floats also, just heavier. The foam is only the filler and it is lightly loaded. The structural part of foam floats is the sheeting. Even though I have the old set of foamies only covered with Balsa and film, now I seal the balsa with one layer of 3/4 glass cloth. The cloth adds a lot of strength, the resin(or polyurethane varnish-easier to work with) seals the balsa. Good (Snell approved) crash helmets have a fiberglass shell and a styrofoam liner...think about it.

I have only been float flying for about 10 years, and r/c flying for about 20. Some of this stuff I learned by doing it the wrong way first. Generally now I can go flying and have a good time and come home with the same number of airplane pieces and credit card balance that I took to the lake. I call that a success.

Hey guys I find this thread interesting,, I have been flying for about 6 years and I have gotten superb, but I have wanted to try a float plane for a long time and I have recently bought from hobby people the Aerophibian, and I must say that it is a great built arf, I have a brand new O.S. .52FS to go on it, I should have it ready to maiden this upcoming weekend so we will see how that goes.[&o]

To Hydro Junkie-- I built a Kadet MkII and added one more bay to each wing, and took out over half the dihedral, and it flew like it never wanted to land, it would float forever. Adding the wing area will probably be good, keep the wing loading down a bit with the weight addition from floats. I never flew my Kadet on water but it handled very sweet in the air, less a trainer and more a sport plane with the decreased dihedral, but still not a fast plane. Could climb like a homesick angel with a .46.