Seaweed (oz10181)

About this Plan

Seaweed. Radio control sport floatplane for .60 power and 3 channels.

Quote: "If you think your tail is dragging, take a look at this float riding bird that dunks its tail for steering. Seaweed by Bob Aberle.

If you live on Long Island, fly radio controlled models and happen also to know Don McGovern, the chances are you will eventually fly hydro R/C. After trying seaplane flying just once you will realize quickly what you have been missing for years. Our many fresh water lakes on Long Island provide fine flying sites in an area where population density has severely limited the number of available flying fields. We also have the option of flying off our salt water, Long Island Sound and Great South Bay. Although the salt spray is very corrosive, hydro flying is nevertheless practical if you use a little common sense in your building and waterproofing.

I first flew a hydro R/C about three years ago at our large Lake Ronkonkoma facility located in the central portion of Long Island. My first subject was a standard Art Schroeder 'Eyeball,' with twin floats attached. One of the first experiences I recall was the initial engine start up. Normal land based flight procedure for me involved electric starting my .60 engine while at low throttle, Next I would grab the transmitter, pull up the antenna and begin taxiing out for my take-off while checking out the flight controls. Well I started my Eyeball at the water's edge on the beach. After reaching for the transmitter I turned around to find my plane already fifty feet out from the shore. So the first lesson learned is that your floating hydro will drift easily at dead idle, especially if the tide or wind favors the center of the lake. When starting up the engine and checking the controls, keep the floats up on the beach or else have a helper hold on to the plane.

Next great experience is taxiing in the water. If you don't provide a water rudder for steering you won't be able to taxi at all. I employed a Nick Ziroli idea which consisted of a piece of aluminum shaped like a small golf club attached to the bottom of the plane's regular rudder. This 'golf club' protrudes just enough into the water to provide good steering. It's true, you do see some modelers wiith elaborate linkages running from the plane's rudder forward along the fuselage and back down the float to a separate water rudder. These fellows are really going through needless effort, believe me. There is no reason to rig a separate rudder on the float.

As I began my take-off run I applied full throttle. Another mistake! The "Eyeball" simply pitched forward with the tip of the prop touching the water just enough to kill the engine. The following dead silence can be exasperating. Instead of walking over to the plane and restarting you must first get into a small boat and row your way out to the plane. Getting back to the starting point again will probably take some fifteen extra minutes. Realizing that I could be all day at this I sought some help from our experienced flyers. Apparently the trick with the fluatplanes is to first hold full up-elevator and then apply the throttle. The up-elevator helps keep the nose up and the prop clear of the water. As the plane builds up speed you reduce the up-elevator. When you just about have the correct take-off speed, you should have only a small amount of up-elevator remaining.

Landings require almost the same technique in reverse_ As soon as the plane touches the water, pull back full up-elevator and at the same time bring the throttle from dead idle back tip to approximately half power. Then proceed to taxi in to the shore line. Taxiing at very low or idle speeds makes water maneuvering extremely difficult. Remember to always employ full up-elevator during taxi, take-off and immediately after landing.

The following year I flew a regular Kaos (oz6251) on floats and again really enjoyed the thrill of R/C hydro. This past season I decided it was time to put all my experiences together into a design of my own. Before getting into the construction end of the 'Seaweed' I thought you might be interested in how I arrived at this particular design.

One of the first problems that surfaced with both the Eyeball and the Kaos was the method of float attachment. On any low wing or even mid-wing plane you usually have to connect the rear of the floats to the main landing gear wires which are mounted on the wing. The front of the floats then get connected to the nose gear which is mounted on the fuselage. What this all means is that the floats have to be removed each time the wing is removed. Since you must disassemble the plane to transport it you end up constantly mounting and removing the floats. This problem was eliminated by going to a shoulder wing configuration where the wing mounts on top of the fuselage.

In this instance both floats mount permanently to the fuselage. I always objected to all the wire bending necessary to connect the floats. Bending 5/32 or 3/16 in diameter wire is no easy job. To simplify the float mounting I chose two Hallco aluminum landing gears. True, they cost considerably more and in fact they weigh more, but they sure make the float mounting easier.

By the way, I received another benefit from the Hallco gears. Because of the rigid mount provided, it was possible to eliminate all the cross wires which usually are required to prevent the floats from moving outward under load. I had been told that all those cross wires create considerable drag. The elimination of these wires made a much cleaner design for water maneuvering.

You are probably wondering what happened to the ailerons. Well, our local hydro contests call for all kinds of crazy things, except rolls. To separately waterproof an aileron servo in the wing only creates additional problems. Hence, no ailerons and instead a wing with 5 degrees dihedral on each side. Basic flight steering is performed by the rudder.

Speaking about that rudder, why underneath? I always wanted to build an R/C job with an inverted rudder reminiscent of my old Free-Flight days. For a land based plane this is impractical since you would need an extremely long landing gear to clear the rudder on take-offs. Since this design is dedicated strictly for hydro use I finally got my chance. With the rudder inverted like this it was easy to establish its height such that about an inch or so actually protrudes into the water. Thus the plane's rudder performs the steering function while it is in the water.

The partial V tail, with 20 degrees of dihedral on each side, came about after a discussion with fellow clubmember, Nick Ziroli. I had originally wanted a very small amount of dihedral in the-stabilizer purely for appearance sake. Nick suggested that the greater dihedral angle might provide for some additional stability at the moment the plane is rotated for take-off. Well at any rate it sounded good so I added what appears more like a conventional V tail. The elevators operate as normal. They do however, require a 'tee' connection at the rear of the fuselage.

The final consideration was waterproof-ing the plane and radio. My Kaos had the usual control rods which exit out slots near the tail, connecting to the rudder and elevator. As the daily flights progressed, water would penetrate these control rod slots and as a result the unpainted balsa wood inside the fuselage would absorb water like a sponge. The more water, the more tail heavy the Kaos got. The last flight of the day would almost end in a snap stall on take-off since the CG had been moved so far aft. This problem was easily corrected by using Sullivan Gold n' Rods (nylon rod within a rod). Of course the radio also had to be protected. This proved to be a simple job. I actually built a waterproof box in the fuselage directly under the wing..."

Seaweed, Flying Models, March 1973.

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Supplementary file notes

Article pages, thanks to RFJ.

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