Sea Gull (oz17007)

About this Plan

Sea Gull. Simple chuck glider model. Wingspan 18 in.

Quote: "This '76 Nats-winning indoor glider would be a good choice for the Cat II site at this year's Nats. Give it a try! Sea Gull, by Jean Pailet.

Like good wines, good Hand-Launched Gliders seem to get better with age. At least, that has been the case with the SeaGull. It is now entering its 10th year of competition and its performance has continued to improve a little each year as the design has evolved through the past decade. The high point in its career (at least for the time being) came at the 1976 National Championships, when Barry Pailet won the Senior Indoor Hand-Launched Glider event with his latest version of the SeaGull (which is the one depicted in these plans). This design also placed 2nd in Junior IHLG at the 1975 NATS, and 3rd in Junior at the 1973 and 1974 Nationals.

Since many of the indoor sites where we fly - Cantiague Park on Long Island, the Dumont Gym at MIT near Boston, Princeton University's Jadwyn Gym, as well as the 1974, '75, and '76 Nationals have ceiling heights of nominally 50 to 65 feet (within the AMA's Category II limits), we designed the original SeaGull with that height criteria in mind. Now that we hear that the indoor site for the 1979 NATS in Nebraska will also be at about the 55-foot ceiling height mark, it looks like the SeaGull may well extend its Nationals competition activity for at least another year.

Two other major criteria guided the design philosophy: Keep it simple so that a Junior could build it quickly and easily (sons Bruce and Barry were both young Juniors when the design first took shape), and keep it light for top performance. The key factor in achieving these two goals is the wing, with its simple triangular airfoil and single dihedral joint.

Aside from the weight of the materials themselves, the amount of glue used in the construction process is probably the prime weight factor in Indoor model design. Therefore, we reasoned, let's keep the number of joints to a minimum by using simple dihedral rather than multi-jointed polyhedral in the wing. The straightforward triangular airfoil keeps the actual volume of wood in the wing to an absolute minimum (for a given thickness and chord there is no effective airfoil which is lighter) and enables young hands to produce an accurate wing quickly. While it may be argued that a more conventionally contoured airfoil is aerodynamically more efficient, we feel that the weight savings of the triangular foil make it at least as effective in achieving maximum possible duration - and that, after all, is the ultimate goal in designing a glider for competition.

The accompanying plans are intended to give all the information necessary to construct the SeaGull. Therefore, we'll keep these written instructions to a minimum.

We've built these gliders using spruce instead of hard balsa for the 1/8 by 1/4 main fuselage piece, so you can try that if you prefer, but we found no significant strength advantage and, of course, there is a slight weight penalty. Otherwise, stick with the wood types/ weights indicated and work towards a weight of 10 to 12 grams for the specified ceiling heights. The one place we do compromise a bit on being weight-conscious is in using epoxy glue for the wing dihedral and wing-to-fuselage attachment joints. This is the single most strength-critical area on the model and, used judiciously, the epoxy will give a significant strength advantage with minimum weight penalty..."

Direct submission to Outerzone.

Supplementary file notes

Article.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction