Mikerjf

Never had or flown a seaplane before and got the urge to do one from scratch. I know it'll fly, but I don't know what it'll be like in the water. Like to get some opinions from people that have flown seaplanes.

Thanks

Mike

Wayne22

My Feedback: (2)

That looks awesome..... you will probably need some spray rails on the twin to keep water out of the props.

Mikerjf

I kept the bottom flat to cut down on some sanding and I heard that it works OK. Also I didn't add the twin setup until later. I can sand in a keel and spray rails later. Thanks for the heads up.

Mike

Mikerjf

Hoping for a little more feedback? Any input would be greatly appreciated.

Thanks

Mike

JimCasey

My Feedback: (1)

Looks cool to me. Flat-bottom is probably the best idea with limited power.

BTW: You might sand in a keel but only if you have adequate bouyancy. Removing material from the hull will make it float lower in the water. You'd have to be artistic to sand in spray rails/chines. Adding a strip of tri-stock along the edge serves well as a spray rail. Take it pretty far forward. It can start 2 inches in front of the step, but it needs to go forward to the static waterline. The chines add lift to the hull, capturing/deflecting water that wants to squirt out the side as your hull moves over it. The water flow is just like the waves that are thown out by a car tire rolling through a puddle. You want to get the hull up on top of the water so the hull is over the 'bow wave" that is thrown forward.

Your rudder extension to act as a water rudder is pretty neat. Make sure it does not hit the surface of the water except when you are taxiing. If you dig it in during your takeoff run, it will be more "run" than "takeoff". As soon as the rudder hits the water it will slow you down.

I presume you have a flat-bottom airfoil??

Mikerjf

Jim;

Airfoil's 15%t symmetrical, span's 40 inch (400 sq in).Plane's 36" long with a 4" beam, 25 oz as a single, 35 oz as a twin. Plane should be fully aerobatic with either configuration (can't wait to try knife edge).The original design had chines and spray rails (bottom looked like a squashed upside down W) dimensioned from Andy Lennons book Model Airplane Design. I left enough foam in the nose to sand it in later if I need it. I had no clue as to how to size the water rudder so I left it grossly oversize. It's coroplast so the plan is to hit full power and see how much the tail lifts out of the water and cut it off to keep about 1/4" in. Configured as a single the water line's just above the step. The twin configuration gets it about 3/8" above the step.I'm guessing you take these off like a taildragger, up elevator to plant the tail initially and then let the tail fly when it builds up some speed (is that when the water rudder should be out of the water?). Other than the rudder my only concern is the cg, I kept it high to minimize the pitching moments but that's not optimum for water handling.Thanks for the input, have to check out your website.

Mike

JimCasey

My Feedback: (1)

Start the takeoff run with full up, to help the hull get on top.
After humping ( and if you read Andy Lennon's book, you know what that means), release elevator. Let it get up to takeoff speed, then breathe on the elevator to get the plane airborne.

The water rudder should stick down no farther than the height of the step behind the sternpost of the float. Or if your floats are exceptionally buoyant, let the water rudder touch the waterline when floating dead still. With power and elevator, you can then get the WR into the surface. If the WR is not engaged with the surface, then you can just chop power and the plane will weathervane into the wind, aligning itself for the takeoff run.

With your coroplast WR, seal the cells on the bottom with tape or you may start scooping water through the rudder
and out the top. It would look cool but it would keep you from getting airborne, or make you stall if the hull did get off the water. (If the wing takes off, but the rudder digs in, you're a fraction of a second from a snap-roll.)

Full-size seaplanes retract the WR for takeoff, and only use it for displacement taxiing.

Carlos Murphy

My Feedback: (72)

You may not want the tip floats to be in the water when the hull is "on the step". A float could dig in and turn the plane while at high speed taxi during landing and take off .

There's nothing prettier than a 100 inch PBY on the step...

Mikerjf

Jim;

Thanks for the takeoff tips. Based on your explanation, I'll probably have to remove half or more of the portion of the rudder below the rear of the fuse. Didn't think the coroplast rudder would scoop water, but now that you mention it you're probably right. Think I'll leave it open for the first flights and see if it does, it would look pretty cool.

Checked out your website. Wow, thats some flying field! You and your planes in any of the pics?

Carlos;

My tip floats might be a little too high. Configured as a single, they're about 3/4" out of the water when the planes floating. Configured as a twin, they're out 1/4". On step they're 1-1/4" out. Too high?

Thanks to all of you for input you've been really helpful, also appreciate you're not raggin' me about the color (only thing I hate about pink foam is that its pink). Once I get it flying and finished up I'm thinking a Coast Guard color scheme. If this winter ever goes away I'll put it in the first unfrozen lake I can find and let you know how it went.

Mike

JimCasey

My Feedback: (1)

Suggested height for the bottom of the tip floats is even with the top of the step. When you're slow, they stabilize you. On takeoff run, they just dance on the water occasionally. If too high, they won't help you taxi and if they don't touch until the plane is 'way outa shape, they'll cause a water loop.

Not my planes in the club website. I moved 6 months ago and shut down my old website. Haven't reactivated it.

Mikerjf

Well, finally got this thing in the water. Pretty much all of the rudder below the fuse is gone (too draggy). Plane flies nice with the single, not to sure about the twin yet. Tip floats seem to be OK, hasn't water looped yet. First tests were with the single, the rudder got trimmed there. Tried to ROW but the plane just kind of goes nose high and won't lift the tail and get up on the step. With the twin it did pretty much the same thing and actually got off the water, but it stayed nose high and just kind of popped off (never really got up on the step and I think the wing was above stall when it popped out of the water) rolled left and sort of landed. Hand launched it after the semi successful ROW and found that the fuse has a little leak. Plane went out about 200 feet I banked it left and the water got into the receiver and that was pretty much the end of that. Luckily my buddy had a boat and we got everything back. All the electronics worked OK once I dried them out. Any suggestions?

Thanks

Mike