Elastic Launched Glider B

AirplaneMan
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Re: Elastic Launched Glider B

Post by AirplaneMan » February 7th, 2020, 9:50 am

My bank angle is around 25 degrees and my inclination angle is around 60 degrees. Also, would flap deflection make a difference?

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Re: Elastic Launched Glider B

Post by bjt4888 » February 7th, 2020, 10:13 am

AM,

Flap deflection should be even and approximately 3/16" to 1/4" for initial tests.

Some gliders require more bank angle, especially if wing wood is very light and flexible. We've had gliders that required 90 degrees. Test this incrementally adding 5-10 degrees per flight at low power and at a lower inclination angle like 45 degrees. Once you find the successful bank angle, add power and inclination together (ex. more inclination requires more power.

If this doesn't work, something is misaligned (rudder, warped fuselage, wing not mounted centered, warped wing, etc.). I assume that airplane weight is light and typical and CG is per plan.

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Re: Elastic Launched Glider B

Post by Booknerd » February 11th, 2020, 4:00 am

Hello everyone!
I'm kinda new to the chat. Anyway, just wondering if anyone else is making their glider?
2020 Events: DyPlan, Fossils, ELG, Road Scholar, some Disease Detectives
2019 Events: Disease Detectives, DyPlan, Fossils, Pentathlon(Trial), WIDI, Experimental Design, and a little Herp
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Re: Elastic Launched Glider B

Post by coachchuckaahs » February 11th, 2020, 9:38 am

Booknerd wrote:
February 11th, 2020, 4:00 am
Hello everyone!
I'm kinda new to the chat. Anyway, just wondering if anyone else is making their glider?
I assume you mean making it from scratch rather than a kit.

Our team has made a number of gliders this year from scratch, and they won Regionals in NM with these planes. The kits on the market are quite good. Scratch building is rewarding, and may be quick if you have materials. The nice thing on the kits is getting everything together, especially the hard-to-obtain Graupner Vectorboard foam if you choose to go foam on the flaps.

We are currently using light balsa for the entire wing, with C grain leading edge and A grain flaps. However, some have found that higher ceilings are not kind to balsa flaps, as launch speed lead to flutter and failure. Ceilings to 30 feet should be OK with all balsa. Last year we did 40' no problem, but the balsa was more stout with the higher minimum weight.

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2016 C WS 8th place
2018 B WS 2nd place
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Re: Elastic Launched Glider B

Post by PayalParikh » February 13th, 2020, 12:31 pm

Hi, we are doing Elastic Launched Glider for the first time. It might be a very basic question, but can someone explain us how to measure incidence?

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Re: Elastic Launched Glider B

Post by coachchuckaahs » February 13th, 2020, 12:44 pm

PayalParikh wrote:
February 13th, 2020, 12:31 pm
Hi, we are doing Elastic Launched Glider for the first time. It might be a very basic question, but can someone explain us how to measure incidence?
Pick a reference line that is straight. Top or bottom of fuselage (whichever edge is not tapered. Measure the height of the wing leading edge and trailing edge. The difference is incidence. This can be converted to degrees using trig, but not needed. This assumes stab is glued to the reference line as well (0 incidence on the stab).

On the gliders, it is perhaps a little more difficult if you have flaps. Do you project straight back or use the flap TE? If you project straight back, then you also want to measure flap deflection and stiffness.

We typically do not measure wing incidence. Instead, we mount the wing to the pylon so it is set to 0 incidence on the main part of the wing (ignoring flaps). Then we mount the pylon to the fuselage in a movable way, and shim either the LE or TE as needed to get good flight. Then we track how many shims (card stock). So the number of shims is our measure of incidence.

Coach Chuck
Coach, Albuquerque Area Home Schoolers Flying Events
Nationals Results:
2016 C WS 8th place
2018 B WS 2nd place
2018 C Heli Champion
2019 B ELG 3rd place
2019 C WS Champion
AMA Results: 3 AAHS members qualify for US Jr Team in F1D, 4 new youth senior records

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Re: Elastic Launched Glider B

Post by Pythagorean » February 17th, 2020, 5:57 pm

Hello,

This is my second year competing in ELG and we just built a Super Protege using the hollowed/tapered carbon fiber fuses and the lightest parts we have. At one point in time, we were able to do 22 seconds in our ~25 ft gym, so pretty decent, but without making any changes to the glider, the glider gained ~.1g and began to fight itself on turning direction. When we originally flew the glider, it turned right, but now it comes off the launcher turning left, transitions left, but as soon as it begins to glide starts to turn right. We completely re-did the glider to get it to turn left, but have not seen nearly as good of results. Thoughts?
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Re: Elastic Launched Glider B

Post by builderguy135 » February 17th, 2020, 6:00 pm

Pythagorean wrote:
February 17th, 2020, 5:57 pm
Hello,

This is my second year competing in ELG and we just built a Super Protege using the hollowed/tapered carbon fiber fuses and the lightest parts we have. At one point in time, we were able to do 22 seconds in our ~25 ft gym, so pretty decent, but without making any changes to the glider, the glider gained ~.1g and began to fight itself on turning direction. When we originally flew the glider, it turned right, but now it comes off the launcher turning left, transitions left, but as soon as it begins to glide starts to turn right. We completely re-did the glider to get it to turn left, but have not seen nearly as good of results. Thoughts?
It might be the flaps. If they're uneven or sanded even a little bit differently, that could make it turn a different direction during launch than during the glide.
HSN '22 & DMAH Co-Captain
6-time medalist in Nationals 2019
2020 Sounds MIT and Princeton Champion
2020 (and probably 2021 :( ) Events: PPP/Sounds/Wright/Code/PaRaSiToLoGy

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Re: Elastic Launched Glider B

Post by Pythagorean » February 17th, 2020, 6:10 pm

builderguy135 wrote:
February 17th, 2020, 6:00 pm
Pythagorean wrote:
February 17th, 2020, 5:57 pm
Hello,

This is my second year competing in ELG and we just built a Super Protege using the hollowed/tapered carbon fiber fuses and the lightest parts we have. At one point in time, we were able to do 22 seconds in our ~25 ft gym, so pretty decent, but without making any changes to the glider, the glider gained ~.1g and began to fight itself on turning direction. When we originally flew the glider, it turned right, but now it comes off the launcher turning left, transitions left, but as soon as it begins to glide starts to turn right. We completely re-did the glider to get it to turn left, but have not seen nearly as good of results. Thoughts?
It might be the flaps. If they're uneven or sanded even a little bit differently, that could make it turn a different direction during launch than during the glide.
Thanks for the quick response.

We believe that the wood was warped so that the glider would turn left (against the flaps) since the flaps would be forced up and less effective, and as the glider slowed, the flaps would take over. The issue with this is that our vertical stab was curled ~10 degrees so that the glider would turn right and in theory, the vertical stabilizer is more effective at high speeds.
Scioly 2017
Bottle 2/?
Road 5/9
Meteorology 8/?
2018
Roller 13/don't want to know
Road 2/9
Meteorology 5/15
2019
Roller 5/Still don't want to know
Road 3/9 (EVERY YEAR!!!)
Meteorology 2/11
DP 7/24 (warm body both times)
ELG 3/7 (So close!)
2020
ELG
Road
Meteorology
Density (Coach and Participant)

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Re: Elastic Launched Glider B

Post by builderguy135 » February 17th, 2020, 6:29 pm

Pythagorean wrote:
February 17th, 2020, 6:10 pm
builderguy135 wrote:
February 17th, 2020, 6:00 pm
Pythagorean wrote:
February 17th, 2020, 5:57 pm
Hello,

This is my second year competing in ELG and we just built a Super Protege using the hollowed/tapered carbon fiber fuses and the lightest parts we have. At one point in time, we were able to do 22 seconds in our ~25 ft gym, so pretty decent, but without making any changes to the glider, the glider gained ~.1g and began to fight itself on turning direction. When we originally flew the glider, it turned right, but now it comes off the launcher turning left, transitions left, but as soon as it begins to glide starts to turn right. We completely re-did the glider to get it to turn left, but have not seen nearly as good of results. Thoughts?
It might be the flaps. If they're uneven or sanded even a little bit differently, that could make it turn a different direction during launch than during the glide.
Thanks for the quick response.

We believe that the wood was warped so that the glider would turn left (against the flaps) since the flaps would be forced up and less effective, and as the glider slowed, the flaps would take over. The issue with this is that our vertical stab was curled ~10 degrees so that the glider would turn right and in theory, the vertical stabilizer is more effective at high speeds.
That could also be possible. I recommend either strengthening the wing with CF or preferably just completely remaking a new and unwarped glider. Be sure to sand evenly, especially toward the TE of the balsa section of the wing (and only on one side!) so the glider will not warp in the future. The flaps must be glued evenly as well against a flat surface so it doesnt warp.

Hope this helps.
HSN '22 & DMAH Co-Captain
6-time medalist in Nationals 2019
2020 Sounds MIT and Princeton Champion
2020 (and probably 2021 :( ) Events: PPP/Sounds/Wright/Code/PaRaSiToLoGy

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