Elastic Launched Glider C

[Asteroidea]

Do you think a flapper glider would be ok for a 40 ft ceiling? Or should I go with a regular glider instead?

[bjt4888]

Astroidea,
A flapper glider could be very successful in a 40' ceiling height site. See the website "Hip Pocket Aeronautics", Builders Plan Gallery, Indoor Gliders, "Cat 2 AMA Record Standard Class Glider" plan by "OlBill". Of course, this plan is for AMA class and the wingspan would have to be reduced to meet the 28cm SO limitation and the nose radius would have to be increased. Also see Hip Pocket Aeronautics, Builders Forum threads for "Indoor Glider" and "Science Olympiad". If you do not have experience building and adjusting flapper gliders, there are a number of posts from national glider champions in these two threads relating experience with flappers and some information about constructing and adjusting a specific designed flapper glider for SO 2014 rules that the schools I am coaching this year are using. If you don't already have experience with flappers, be aware that they give excellent performance but they also require a certain level of time committment.

Bjt4888
AMA member (off and on since 1968)

[Asteroidea]

I saw that plan, but it seems like many many modifications would have have to be made. And based on his own posts it's implied that it seems more of a 60-70 ft type of glider. And the fact that I lack depon and carbon fiber. I already have a built flapper that can hit the ceiling of the gym I fly in sometimes, so I figure that it should be fine for 40 feet.

[mrsaturns]

Thank you so much for your help Mr. Anderson! And for all you do for MYSO!!

[jander14indoor]

More than welcome.

Michigan State Tournament over for this year. I understand winning times were on the order of 27 seconds for a single flight, approx 30 foot ceiling (I didn't measure it, was stuck in headquarters).

Best of luck to all those teams heading to nationals, and good work to ALL the students who participated in SO this year. I guarantee you learned far more than you realize if you made any reall effort.

Regards,

Jeff Anderson
Livonia, MI

[calgoddard]

It is important to understand that a flapper catapult launched glider (CLG) is best suited to low ceiling height environments.

Personally, I don't consider a gym with a 40 foot ceiling height to be a low ceiling height environment.

A flapper CLG with trailing edge sections on its wings that do not have the correct amount of flex may have excessive drag, and therefore may have difficulty achieving an apogee close to a relatively high ceiling. Remember a good indoor CLG flight has three components:

1) apogee as close as possible to the ceiling (or the underside of any major obstructions such as light fixtures and beams);

2) rapid transition to a stable glide, i.e. no excessive loss of altitude before the glider assumes a steady glide; and

3) a slow descent rate.

If a team can consistently achieve these three components with a canard glider it would be hard to beat at the 2014 SciOly Nationals in view of the 30% bonus for a canard configuration. As I previously indicated, I personally saw canard CLGs fly quite well in the 2013 ELG competition in our large regional competition, which is intensely competitive in flying events every year that they are official events.

[bjt4888]

Jeff,
I attended several hours of the Michigan State Science Olympiad Tournament Elastic Launch Glider event and saw a number of high-quality gliders. The ceiling height was measured using a laser range-finder and we estimated that the height to the base of the girders at the peak of the ceiling was about 28 ft. The participants from Canton HS and Saline HS had excellent gliders and I observed a number of flights from these two students in excess of 26 seconds that were launched safely under the girders. The students that I coached from Okemos HS and Holt HS both had gliders capable of 1.07 seconds per foot of launch height and were both getting 26+ flights in practice. Although they competed well, their official flights were not quite as good. But, of course, the objective of the event was really met during the months of preparation, design evaluation, testing and data gathering, and learning about aerospace engineering. I saw a big bunch of students excited about science!

Brian Turnbull

[jander14indoor]

Glad to hear your students enjoyed the event, both the prep and the execution. Seems they "got it", always good to hear.

Thanks,

Jeff Anderson
Livonia, MI

[calgoddard]

I wanted to put in one more pitch for rubber powered Wright Stuff for 2015 instead of e-Wright Stuff. The published schedule for the Science Olympiad Summer Institute to be held July 14 - 18, 2014 in Phoenix lists Wright Stuff so it appears likely that event will finally return to Division C next year, after a seven year hiatus.

There will apparently be a vote on rubber versus capacitor later this month, after the National competition at UCF.

I see many competitive and cost issues with a capacitor powered indoor airplane.

Also, I can't imagine the disappointment of students that have practiced e-Wright Stuff for months, only to suffer an electrical failure (e.g. short, open connection, capacitor failure, switch failure, electric motor malfunction, etc.) that forecloses any flights during competition. Virtually any rubber powered airplane that has been through ten test flights (as necessary for the required flight log) will fly at the competition, the only question is, for how long? Yes, I know, the students should have two airplanes just in case, but many students do not have two workable airplanes at the competition for various reasons.

There is a long history of rubber powered indoor flight, and experienced mentors can be found in most parts of the country. Rubber and balsa are inexpensive and suitable plans are available on the Internet - just adjust the
wing span and chord to meet the rules. Many teams have winders and rubber left over from the Helicopters event. Students that competed in the glider event the last two years will learn a great deal transitioning to rubber powered flight and trimming for endurance.

The 2010 Division B Wright Stuff rules were very workable. I suggest that the motor weight max be eliminated to make check-in easier, and to encourage students to experiment with the optimum motor weight for their airplanes. A suitable max wing span, e.g. 40 cm, and a suitable minimum airplane weight, e.g. 7 grams, are all that are needed to keep flight times below 3 minutes, even for top competitors. There is no need to limit the chord of the wing and stabilizer. Let students experiment with different aspect ratios. There will be less cookie cutter airplanes at the competition. Why limit prop diameter? Again, let students experiment - bigger props are heavier than smaller props, but . . .

It appears that Division B will have Elastic Launched Glider in 2015 and middle school students that compete in that event can progress to rubber powered Wright Stuff in two years.

[bjt4888]

I would like to support the comments by "calgoddard" about the possibility of electric motor powered Wright Stuff. I think that the students get a lot out of the complexity of analysis that rubber power provides. The need to evaluate and test rubber torque to optimize duration and rubber tension against structural strength of the airframe would be lost with the electric motor. Students that I coach in rubber powered events are included in discussion and analysis of many concepts, including: rubber batch data evaluation, rubber torque vs. unwind time, rubber x-section & length data and analysis, wound rubber motor tension impact to airframe and design methodologies to address, Young's Modulus of elasticity calculation by balsa buckling test (Slobodan Midich spreadsheet), etc. All of this science would not need to be part of the electric Wright Stuff event.

I am definitely not anti-electric motor as I spent years of my youth building and modifying HO-scale slot cars. I just believe that the rubber motor power provides a much more interesting and more complex problem. Also, the complexity of the rubber motor system is very accessible. Designing and testing for many data points is as simple as tying new motors, winding and launching repeatedly. Successful electric power system modification and testing, while possible, requires pretty close tolerance machine work or a certain amount of experience. I have modified/replaced electric motor magnets, altered commutators, rewound armatures, etc. and this is pretty time-comsuming work that is likely to only reap performance benefits after quite a bit of experience. The only electric motor system modifications that I could see the students playing with would be things like gearing, propellor pitch/diameter/shape and possible introduction of a programmable chip (if allowed).

Just my two-cents.

Bjt4888