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F2D News ľ 18 July 2005
Mark Rudner
rudner@mit.edu

LATE BREAKING F2D NEWS: I just received word that Neil Simpson won F2D at the Nationals, and that Ken Hargreaves got 3rd place as well. I was really excited to hear that, and I hope that everybody else will join me in congratulating them on this achievement. It makes me happy to see that F2D in New England has really taken on a life of its own and that it is giving our guys more opportunities to compete, to have fun, and of course to take home some loot at the end of the day.

Unfortunately, I wasnăt able to attend the Nats this year, and likewise will not be able to attend the upcoming triple elimination F2D meet in Chicago. It looks like ităs going to be a real big meet though, so I hope everyone who can go will enter so that in future years they may decide to have it again.

This past weekend I spent two days in Philadelphia training with Andrey Nadein, a good friend of mine and an accomplished F2D pilot who is preparing for the Chicago contest. This was the second opportunity Iăve had to train with him this summer. The most notable aspect of our training that Iăd like to mention is Andreyăs new self-launcher (╚stooge╔). This handy contraption is based a design used by Roy Glenn, though Iăm not sure whether or not he is the originator of the design. Using the stooge, we were able to fly combat matches for hours on end without any additional help. It also allowed Andrey to trim all of his models by himself beforehand.

Although I wanted to get a picture of the launcher, I forgot to bring my camera with me so that will have to wait until a future issue. In the meantime, hereăs a substandard description. The Z-shaped skeleton of the launcher is all made from 1.5╔ PVC pipes, which are attached by standard 90o bend and T connectors available at Home Depot. Metal clamps secure the base of the launcher to the ground. The release mechanism is discussed below. Ităs a simple, cheap, and effective design.

Self-launching devices can be very dangerous if not properly designed and built, so if you decide to try to make one for yourself, it is very important to test it carefully and extensively before putting it into regular service. If the model is not held securely enough or does not get released reliably, serious damage to your models, yourself, or innocent bystanders could result. I was present with Andrey for the initial testing of his launcher. Even though he had based the design on Roy Glennăs tried and tested device, it still took us an hour or so to get the bugs worked out of his particular version. That shows that these things do require fine-tuning, and must be treated with the proper respect and caution.

Our biggest hang-up was the release mechanism. When designing a release mechanism for a self-launcher, ităs important to make sure that it releases the model straight (tangential to the circle) and evenly every time. In this particular design, one strap over each wing is used to hold the model. The front of each strap has a hook that grabs onto a pin inserted through the front of the launcher. To release the straps, the pilot pulls on a long string that is attached to the pins. In a design like this where both wings are held independently, ităs imperative that the inboard wing is released before or simultaneously with the outboard wing, but NOT after. If the outboard wing is released first, the model will have a tendency to torque in towards the pilot. As you might guess, this leads to undesirable results.

Another thing to watch out for if you design a launcher that uses an additional string for the release mechanism is the management of this string. It is important to ensure that this additional string will not become entangled with the flying lines during takeoff. In our case, we decided to run the string through a U-shaped hook stuck in the ground about 15 feet into the circle. In launch configuration, this kept the arming string safely below the lines and succeeded in preventing further tangles.

So far in our training sessions we have logged about 40 matches, with 2 serious mid-airs. Any time you fly lots of matches, collisions are bound to happen, but the rewards in terms of improvements in flying are well worth it. This time we got rained out late in the afternoon before we really felt that our training was complete for the day, but it was good to get out and do some flying. Hopefully weăll get a chance to continue in the coming weeks. In the meantime, I hope everyone else out there is getting the chance to put in some good flights as well.


If you have any questions or comments, please email Mark at rudner@mit.edu