mr_matt

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First, gorgeous modelling, but I cant get my head around what you did here. Are you making the floats deeper, narrower, different angle? Thanks for posting and I hope you can explain it to me.

Square Nozzle

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Matt, if you look at many full scale amphibs you'll notice that the edge of the water contact surfaces has what I will call a fence extending down towards the water. This directs the water down and helps lift the plane out of the water. If you're familiar with the GP Seawind design you will recall that the tip floats have a sharp outer edge but the inboard edge has a large radius. From my boat racing days I learned that a round edge on a water riding surface is a prescription for disaster. In high speed applications the water will ride up on that round edge creating drag and pull it down. Result, the hated tip float sinking and water loops. What I did was simply eliminate the inboard radius by filling it with an epoxy and microballoon paste. Next, with that same epoxy paste I put a "fence" all around the tip bottom surface. The tip depth (with the exception of the 1/8" "fence"), width and length remain the same as original. The water gets deflected down off the fence and the tip float literally skips across the water. It's all about Newton's third law. The deflected downward water pushes the tip up. I was thrilled when I flew the plane on it's maiden flight and saw the wing tips skip across the water. In the photos I provided the wing is upside down and you can see the fence that I created. In reality the guys that are extending the tips are doing nearly the same thing without the fence. They have eliminated that poorly designed tip float with the radius on the inboard side and created a sharp inboard edge. I just don't like the look. Someone mentioned in a previous post that the extended tips made the plane look like it has training wheels.

jrf

My Feedback: (551)

Beautiful work, and a good solution. Here is another way.

I used to have a glow powered Seawind and experienced my share of waterloops. I just finished my electric powered Seawind and the stock, unmodified wingtips skip across the water just like yours do. Why? Because the center of gravity of the electrically powered Seawind (esc and batteries in the lower fuselage) is much lower, making the airplane less likely to roll the wingtip under.

Square Nozzle

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The lower CG may have a factor in your plane but I'll bet that if you look at the tip floats you'll find that the large radius on the inboard edge has been eliminated and it is now a sharp edge.

jrf

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The inner edge has a radius of about 1/4".

Square Nozzle

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I haven't seen the tip floats on the foamy so I can't comment. Likely the tips are so light that they naturally resist sinking and the "sharp" outboard edge does all the work. But I'm convinced that those tips will get pulled down if the water rides up on the tip radius. It's a fact of nature and you can't avoid it. I once saw a home built foamy that the guy put big foam wheels on thinking that since to foam would float he could fly it off water as well as land. The wheels/floats sank like a stone when he put the power to it.

jrf

My Feedback: (551)

Mine is the 60 size fiberglass/wood, the same as yours. I'm not saying your solution is wrong, only that converting the Seawind to electric power and thereby lowering the vertical CG appears to solve the problem without any wingtip mods. A few posts back I saw that a fellow had used a YS engine and put the fuel tank in the lower fuselage. I'm sure that helped as well.

Square Nozzle

My Feedback: (1)

It seems there are two ways to skin this cat. The lowered vertical position of the cg reduces the tipping pressure on the wing tip thereby keeping that inboard edge out of the water. Good info.

Bob93447

The other "modification" that really helps avoid waterloops when taking off with the 60 size Seawind is to minimize rudder throw during takeoff. I set mine up so that during takeoff I am using a 10% rate on the rudder and this has allowed me to avoid waterloops as long as I am taking off into the wind with enough patience to wait for big boat wakes to pass. As long as you are pointed into the wind when you start your takeoff run it's pretty stable. Others have achieved a similar result by cutting down the water rudder but with a multi-rate transmitter using a very low rate for takeoff allows you to use the large water rudder for taxi.

jrf

My Feedback: (551)

On my first Seawind, the water rudder fell off on the first flight. Taxiing with that big air rudder was difficult, but doable. On this second one I cut the rudder down to about 1/3 of it's original size. That seems to be a decent compromise, but I do agree that the Seawind should only be taken off directly into the wind. That makes leveling the wings MUCH easier and you may not have to use the rudder at all.

Square Nozzle

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Do yourself a favor and get rid of that foolish round edge in the inboard side of the tip float. With the fence on the bottom edge of the tip float I don't have to worry about rudder size, absolute into the wind takeoffs and using the rudder to keep the wings level. If the wing droops in one direction or another the tip floats don't even hint of a grab. A touch of up elevator, slow throttle advance and the plane glides across the water and lifts off.

mr_matt

My Feedback: (10)

I got a few flights on mine yesterday. I did have a pretty healthy crosswind but I did not have any problems with it. I will say that the rudder should basically be locked in neutral during takeoff, as others have mentioned the water rudder is ridiculously too large to use during takeoff

I think most of the advice given in this thread was good. the key for me was holding full elevator on takeoff and I made sure I had even more elevator throw than in the plans and slowly advancing the throttle I mean very slowly.

My wingtips never got near the water so the whole issue of the shape of the tips was really moot for me. I will say the bottom line to this model as you have to be a fairly advanced flyer to be able to manage the control settings on takeoff....holding full elevator, advancing the throttles slowly and all the while absolutely keeping the wings level with full flaps.

Again cross wind was no problem for me, and in the air it basically flew like a warbird. I had an YS FZ110 and I would say it was doing about 85 miles an hour on a rich setting. I moved all of the servos forward (no extra balance weight required), ran a remote 16 ounce fuel tank on the CG, and ran the CG very far aft, maybe 2.25 inches?

I am using past tense as I lost it on a dead cell in a new 2 cell LIFE. I normally run 2 batteries so this is my fault. Too bad it was challenging and flew well

Bob93447

Matt,

It sounds like you had a nice setup on your Seawind. I was surprised that you were able to get the balance right just by moving the servos forward but the 2.25" point is about where the electric powered version works well. What prop were you using on the YS FZ110?

Bob

mr_matt

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Duplicate

mr_matt

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Hi Bob

Yes the balance worked out but the plane still weight 12.5 pounds so I am not sure what was gained. Although the stock control setup with mini servos and a push rod (pitch up) did not look good to me I suppose it works.

3 feet of nyrod is yucky but I did like having big digital servos for everything.

If I had to do it again I would go with stock rudder control but move a full-size digital elevator servo into the tank compartment and run a pushrod to the top of the elevator through the fin.

I also reinforced the pylon and the hull with a lot of glass.

I had 13 X10 prop on the FZ110. The tank setup was nice as you could move it forward and aft maybe 2 inches for cg adjustment.

Also there are complaints about the weight, it feels fine to me but I am used to heavy planes

Bob93447

HI Matt I've taken a slightly different approach to the servos on my current Seawind. There is a new generation of small, lightweight, high torque digital servos that are available so I am using those for both rudder and elevator. I agree that the elevator pushrod is sort of sketchy so I put a piece of small diameter carbon fiber tube around the supplied elevator pushrod so that I end up with a very stiff assembly. This allows me to use the existing mounting locations and maintain very short pushrods.

To reinforce the pylon I added a carbon fiber structure to brace the vertical plywood assembly and then epoxied a piece of carbon fiber sheet to reinforce the plywood "bulkhead" that lies behind the fuel tank that you show in your picture. Since I'm flying at high altitude, 6200', I need to keep the weight down.

I wonder if enough Seawind current and former owners got together and lobbied Great Planes could we demonstrate enough market potential for them to release and improved Seawind. Personally I'd like to see them replace the internal plywood structure in the pylon area with carbon fiber and remove the modifications for retracts as well as removing the nose weight. It ought to be at least a pound lighter.

Are you going to replace or repair your Seawind?

Bob.

mr_matt

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I don't know, if I could pick up a kit quickly, maybe, but between fixing the chopped canopy and fixing the gap behind the spinner, I am not so sure I want the hassle

Bob93447

mr_matt

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wanna sell it? :-)

Bob93447

No, but JRF who last posted on 6-29-17 might sell you the one he just built. Its set up for electric but you might be able to convert it to take your YS. He's in SoCal.

Bob

jrf

My Feedback: (551)

I had a glow powered Seawind a few years ago and liked it. Somebody made me an offer I couldn't refuse for that one and I sold it with just a few flights on it. Then earlier this year a had the chance to buy another and I decided to see how different an electric powered Seawind 60 would be. It turns out that the electric is a bit lighter and has a much lower center of gravity. The result is that it takes off, flies and lands much easier than the glow powered one did. It is quite enjoyable to fly.

But I am planning to move on to the next project. My Seawind is available.

mr_matt

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Hello,

Thanks for the kind offer but electric is just not my cup of tea. But I agree if there was ever an ideal electric conversion, the seawind is it.

I might have seen your other Seawind fly maybe a month ago in Legg Lake?

jrf

My Feedback: (551)

I doubt that my first one was a Legg Lake recently. I sold it several years ago, and they don't seem to last very long ,but you never know.

I had an OS 61 FX in it and it flew quite well, considering that it was top heavy.

Bob93447

If anyone in Southern Australia is desperate to acquire a New-in-Box Seawind there is one available at Nick's Hobby Shop near Sorell, Tasmania. I found it as part of a side trip (my wife made me spend the morning at the market in Hobart) up to the wine country. Since Seawinds are becoming rare, it might be a good deal for someone who does not need to ship it too far.

rowdog_14

My Feedback: (5)

Give a little heart to this thread after 4 years of sleep. Picking up a Seawind tomorrow! Always wanted this plane.