|
|  |
|
|
JPL Annual 2003 Invention Challenge Results Gallery
Entry 16
|
|
| |
 |
| |
|
Comments
1. What did you think of the challenge given (the design of the glider)?
Most of the students found the project "Challenging" and fun. There was some dissent on this, as two of those on the team who did not participate as much indicated a lack of interest. From a mentor standpoint, the project was useful as a team-building activity, and was particularly useful in solidifying time scheduling and budgeting constraints and the need for early construction and testing.
2. What ideas did your team consider in its initial planning?
The team initially tried to modify and use a glider designed and built to compete in the Kern Co. Airshow. This featured a NACA 2412 wing and was large and heavy, designed for a much more substantial (but poorly specified) launch impulse. Testing with a Wright Turn launcher quickly showed the need for a lighter aircraft.
3. What was your final design? (Describe it in a few words.)
A foamboard, balsa, and tissue paper glider using NACA 2412 wings with a 32 inch wingspan, 24 degree dihedral, a single foam and balsa wood spar for a fuselage, flat plate foam elevator and symmetrical wing profile rudder. The wings and elevator mounting angles were designed to fly with the wing at 4 degrees angle of attack for best L/D.. Weight was minimized throughout the subsequent testing process, reaching 105 gm by contest time.
4. What was your testing process and how did you improve your design?
The testing process began with the construction of the specified launcher and adaptation of the existing plane to the launcher. First tests indicated that the initial plane weight was much too high. Tests were then run on the launcher to verify theoretical predictions of launch velocity as a function of the plane weight, resulting in a maximum target plane weight being set. Substantial plane modifications followed, with periodic flight test results. Most modifications were aimed at reducing weight, although an early decision prompted by the flight tests was to increase the dihedral from 15 to 24 degrees for roll stability during the turn. Most informative flight tests were run in the school gymnasium since outdoor wind velocities in our mountains were always too high.
5. What did your team learn at the Regional contest?
That even low wind velocities outdoors could make significant differences in flight paths, and that good performance was dependant on testing and trimming the plane in the actual wind conditions and in the actual launch direction with respect to the wind. Also it was not a good idea to use a screwdriver jammed upright in the ground as a flight target during precontest testing. (A good flight damages your aircraft leading to short-lived ecstasy followed by the depths of despair, followed by fast field repair!)
6. What were your feelings or experiences at the JPL contest?
Generally the students enjoyed the contest. Some were particularly happy to be at JPL for the contest. Others, having been on the winning team last year, were happy to place second this year. The mentors were sorry that JPL tours had to be curtailed this year, however.
7. How would your team improve your design if you were to try again?
Place lightweight supports on the elevator to keep it above the launch hook while launching, and/or place the elevator on top of the rudder. (Based on a careful reading of the rules and some observations at a Regional contest our team expected to be allowed to place two non-moving rails on the launch surface to guide the elevator over the launch hook. When this was disallowed we were in trouble on the launch-one went well but the launch hook scored a big divot in the elevator on the second launch.)
|
|
| |
|
| |
|
