T10 Gull (oz3008)

About this Plan

T10 Gull. Free flight sport seaplane.

Quote: "To combine the features of the T8 Tern and T9 Bleak (oz3017) types a new model, the Gull, was built in summer 1962. The gull-wing, with tip floats were joined to a Bleak fuselage and raked butterfly tail. Whole length of the hull was made 'wet' in order to try any improvement in water run. Span is 63in with weight only 39oz. Results obtained lead to the conclusion that here is the most effective layout. Power-on speed is more than adequate with a fast climb, the glide again nice and slow. There does not seem to be any need to design a long water line in the hull, a shorter after-step portion having all the necessary steering control.

It is this model which is introduced to Aeromodeller Plans Service. A reliable hull form had now been determined with some details not entirely in accordance with ideas commonly approved. All the books tell one to design the hull and step position after the two-wheel undercarriage principle. The splendid water performances of Tern-6 proved that a step location behind the CG position is possible. A stout hull-form, rather broad, gives good heeling stability and most probably is easier for planing, a narrower hull sinking, of course, much deeper.

Instead of a long water line, the shorter after step portion of the hull can be built with a concave water line at the rear, this giving a very strong corrective action, combined with proper mounting angles of tip floats—the model obtains a sort of automatic steering and heeling control. Clearly, these are stronger in effect during water run than the flying surfaces—so the flight trim does not change the water run, but the moment it leaves the surface, flying trim takes over.

A very important point to remember, when designing this type of model is to give the hull bottom in the short straight section just before step location a more positive angle compared to the wing incidence, otherwise take-offs would not be possible. When glide trim is obtained, motor thrust is used to control power-on flight. If the take-off is difficult, then add upthrust. Now this may produce a stall in motor flight. To correct, add ballast in small increments to the nose and retrim for glide with tailplane angle..."

The T10 Gull and the T11 Seal (oz3012) model plans appeared together in the same article, in Nov 1963 Aeromodeller.

Added a supplement version (clearer but no dimensions) of this plan, thanks to Modelholic.

Supplementary file notes

Alternate plan version.
Article.

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