About this Plan
Blackjack. Outdoor hand launch glider model.
Direct submission to Outerzone.
Quote: "Blackjack, by Larry Sargent. Here's a state-of-the-art glider designed to be competitive on only a moderately high throw, by means of a superior glide. Its contest record is impressive, including a first at the '79 Nats.
Outdoor Hand Launched Glider has too long been regarded as a pure strength event, and as such, has always attracted fliers in their youth. Later, they often turn to less physical events. However, cranking up a 16-strand rubber motor or running around the field with a 164-foot towline is hardly sedentary. Every free flight event presents its own unique demands, and all free flight models need to be chased.
Why, then, is HLG so often the realm of youth? Well, not because we outgrow them. Any beginner can readily testify that hand launched gliders are not toys; they can be tricky and frustrating, just as any other free flight. Many are the would-be modelers whose first shot at free flight was HLG (perhaps because these models looked the simplest), and who are now happily back at their stamp collections.
The fact is, many modelers quit flying HLG because of severe and often permanent physical damage to their throwing arms. The list is long and the names on it might surprise you. If being competitive at MG can do this to grown men, what will it do to kids, whose muscles and bones are still growing? Ask any little league coach how careful young pitchers should be and you'll see my point.
A couple of years ago, I was enjoying the wide open spaces of Taft (when you live in LA, it can be a treat to merely see the horizon) and was preparing my 18-inch glider for the contest. When I saw Greg Sussex and Bob Boyer warming up I felt like turning around and going home. I couldn't believe the altitude they were getting! Try as I might, my rollout would be 20 feet below theirs. Finally, straining every muscle, doing my best imitation of an arthritic gorilla, I hung on an instant too long, and planted it in the dry Taft soil.
That sort of thing can ruin your whole day. But it did get me to thinking. Both Bob and Greg are younger, taller, and probably stronger than I am. Without six months of weight lifting (and maybe an arm transplant), I would never throw as high as they did.
Therefore, why not design a glider for only a moderately high throw? It would have a larger wing span, higher aspect ratio, and lower wing loading to make the most out of the lower, lighter lift. The result was the Blackjack, a contest model that can do well on a consistent 80% throw.
Of course, my 80% may be different than yours. All I can say is that my arm never aches, I don't lift weights, throw tennis balls, nor fly more than every other week. Also, I am 33 years old. If this depressing description fits you, or you're just tired of hearing your arm snap, perhaps Blackjack is just the thing for you!
WOOD: In order to be competitive, Blackjack must be able to make about the same dead air time as the popular 18-inch gliders. They may go up higher, but Blackjack comes down lower. This means Blackjack must be built light. If you can't find the right wood, wait until you can. Remember Sargent's Law of Counterproductive Balsa Selection: NO amount of sanding nor accuracy of shape can compensate for starting off with the wrong wood.
CONSTRUCTION: This is the most important part, so take your time. Use a piece 1/4 x 4 x 36. Weigh it. Then get your trusty calculator and figure out it's density per cu ft. For the wing you want to find a piece that is 4-5.5 lb. density. C-grain balsa isn't really necessary, but it helps. You can also glue pieces of 1/4x1 and 1/4x3 together to make your wing. If you do, use a glue that can be sanded.
Cut the outline of the wing and mark the exact center where the middle dihedral break will be. Next, stick pins edgewise into the leading and trailing edges at the center to check the balance. It's not too soon to consider which way the glide turn is to be: left, if you're right handed; right, if you're a southpaw. I am right handed, so all my directions will be for right handed trim. Just reverse the directions if you're left handed. Anyway, the left wing should be slightly heavier than the right wing. Check this before the wing is formed. If it falls to the right side, turn the wing over..."
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