Elastic Launched Gliders B

Pramdoge11
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Orded Info

Postby Pramdoge11 » December 20th, 2018, 2:41 pm

I ordered a kit through Scioly,(in December), but it is arriving in January. All materials say they are allowed in the 2019 challenges, but I am still apprehensive. Any thoughts about what I should do if they are not certified?

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Re: Elastic Launched Gliders B

Postby bjt4888 » December 20th, 2018, 4:46 pm

Pram,

Congratulations on preparing to build an excellent kit. I’m sure that the FF kit meets the rules if you build accurately. Certain steps need to be completed with extra care. For example, the wing dihedral angle needs to be per the kit instructions or the wing projected span may be greater than the allowed 30 cm in the rules.

Read the rules and the kit instructions carefully to be sure you understand them before you start building.

If you have specific questions about construction or the rules, post them here and you will get help.

Brian T

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Re: Elastic Launched Gliders B

Postby prd06 » December 20th, 2018, 5:59 pm

Has anyone built and tested the Freedom Flight or J&H Aerospace kits?
How heavy is your glider? What kinds of times are you getting?

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IvanGe
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Re: Elastic Launched Gliders B

Postby IvanGe » December 20th, 2018, 6:48 pm

Has anyone built and tested the Freedom Flight or J&H Aerospace kits?
How heavy is your glider? What kinds of times are you getting?
I built 4 freedom flight gliders. I screwed up on like 3 of them but they glide very nicely if built according the the directions. With the ballast, my glider is around 4-4.2 grams (still too heavy). The best I've gotten is around 15 seconds but the glider was transitioning at a very low height.
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MattChina
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Re: Elastic Launched Gliders B

Postby MattChina » December 20th, 2018, 7:37 pm

Has anyone built and tested the Freedom Flight or J&H Aerospace kits?
How heavy is your glider? What kinds of times are you getting?
I built one Freedom Flight, its a little more than 3.5 grams. Ive gotten like 5 seconds or so.
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bjt4888
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Re: Elastic Launched Gliders B

Postby bjt4888 » December 21st, 2018, 9:30 am

IvanGe,

When you state that your glider is transitioning at a very low height when it flies for about 15 seconds is it launched to the full height of the site and then sharply turning at the top of the climb and losing altitude before transitioning and gliding smoothly?

If so, and if the glider is built per plan (CG correct or close, stabilizer and rudder unwarped, flaps curved correctly and evenly and decalage angle set initially by test gliding and adjusting the wing incidence), it is possible that a little too much bank is being used during launch. Over-banking or excess rudder offset can lead to hooking. Of course, launch inclination angle and bank angle work together, and probably you are already doing this, experimentation with bank and inclination angle should help you get to some better duration. Be very careful of under-banking though. Launching under banked can lead to the dreaded "hammer-head stall", resulting in a fast dive to the floor and possible breakage.

You are correct that a lighter glider is very desirable. Glider weight and duration are almost a linear relationship for SO gliders. 20% overweight means 20% less duration; approximately.

Brian T.

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IvanGe
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Re: Elastic Launched Gliders B

Postby IvanGe » December 22nd, 2018, 4:09 pm

IvanGe,

When you state that your glider is transitioning at a very low height when it flies for about 15 seconds is it launched to the full height of the site and then sharply turning at the top of the climb and losing altitude before transitioning and gliding smoothly?

If so, and if the glider is built per plan (CG correct or close, stabilizer and rudder unwarped, flaps curved correctly and evenly and decalage angle set initially by test gliding and adjusting the wing incidence), it is possible that a little too much bank is being used during launch. Over-banking or excess rudder offset can lead to hooking. Of course, launch inclination angle and bank angle work together, and probably you are already doing this, experimentation with bank and inclination angle should help you get to some better duration. Be very careful of under-banking though. Launching under banked can lead to the dreaded "hammer-head stall", resulting in a fast dive to the floor and possible breakage.

You are correct that a lighter glider is very desirable. Glider weight and duration are almost a linear relationship for SO gliders. 20% overweight means 20% less duration; approximately.

Brian T.
Yes, that is what was happening. I was able to get it to transition smoothly today at the gym by slightly reducing the ballast and using a smaller bank angle. The best I got was near 17 seconds, although it would've done better but the AC was on so it kept on pushing the plane. Thanks for the advice!
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nats '19:
5th - potions
5th - fossils
9th - buggy

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Elastic Launched Gliders B

Postby BilalHayat19 » December 22nd, 2018, 4:51 pm

Does anybody know the height of the ceiling in the gym at Cornell university?

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Re: Elastic Launched Gliders B

Postby Pastaman202 » December 25th, 2018, 2:55 pm

Does anyone know how high the Centerville ceiling will be?
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Re: Elastic Launched Gliders B

Postby SonicSpeed » December 25th, 2018, 6:56 pm

Freedom Flight's kits are very durable and gets me and my partner some pretty good times... Guru is not as good (in my opinion) but works fair enough.
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