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Author Topic: 2019 Elastic Launched Glider  (Read 2266 times)
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bjt4888
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« Reply #50 on: November 02, 2018, 11:53:26 AM »

Jdp,

My teams use a 6” loop of 1/16” thick Tan SS for the typical school gym ceiling height (25 ft to 30 ft).

I have used a 6” loop of 1/8”, stretched to my full arm span, successfully in a low Category III site (72 ft ceiling). Of course, the glider for this site is built for this extra force. I fly Bill’s Category II record holder for this higher ceiling; an excellent glider that I would highly recommend.

Brian T
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jdpsloflyer
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« Reply #51 on: November 02, 2018, 04:30:35 PM »

Thanks Brian,

Any other pointers about coaching the launch?  It's been two years since I did this and cannot remember where I saw them.

Do you have a plan of the glider with the elliptical wing (the "El Gordo") that I saw on one of the threads you posted on?  I did not see it in the Gallery.  I have a copy your other one.

Jerry
« Last Edit: November 02, 2018, 04:43:28 PM by jdpsloflyer » Logged
bjt4888
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« Reply #52 on: November 02, 2018, 09:21:29 PM »

Jd,

You’re welcome. My launching notes are in the thread, “Flapper CLG for 2014” in the earlier page of this thread. Mostly in my post #4. Let me know if something in these notes is not clear.

Sorry, I am not remembering the El Gordo design. However, I think that semi elliptical is the way to go as all of the top designs and record setting designs are of this platform.

Brian
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Olbill
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« Reply #53 on: November 03, 2018, 12:03:52 AM »

Jdp,

I have used a 6” loop of 1/8”, stretched to my full arm span, successfully in a low Category III site (72 ft ceiling). Of course, the glider for this site is built for this extra force. I fly Bill’s Category II record holder for this higher ceiling; an excellent glider that I would highly recommend.

Brian T

Former record holder.
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jdpsloflyer
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« Reply #54 on: November 03, 2018, 07:12:46 PM »

Jd,

You’re welcome. My launching notes are in the thread, “Flapper CLG for 2014” in the earlier page of this thread. Mostly in my post #4. Let me know if something in these notes is not clear.

Sorry, I am not remembering the El Gordo design. However, I think that semi elliptical is the way to go as all of the top designs and record setting designs are of this platform.

Brian


Sorry, the El Gordo was from dslusarc post #46 in 2016-Elastic launched glider.  I am "throwing one together"  today to see if mine works as well.  Then use it as a demo.  Using foam in place of balsa for flaps.  3/32 light balsa (sanded) and carbon rod fuselage.  All new for me, wet finger design and build, hope it works.

Jerry
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bjt4888
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« Reply #55 on: November 03, 2018, 08:36:09 PM »

Jerry,

Hope it flies well.

Brian
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« Reply #56 on: November 19, 2018, 09:06:05 AM »

I've been getting a lot of emails from far and wide about trimming for ELG contests, so I put together some notes for a guy who noted that he doesn't learn easily from videos. I still haven't gotten feedback from him on this, but if you scroll down this link a little, you'll find my article on trimming. Hopefully someone will find this helpful:
http://jhaerospace.com/resources-for-science-olympiad-competitions/
Any feedback would be appreciated. I'm getting a little overwhelmed with the number of people coming to me for help.
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Olbill
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« Reply #57 on: November 19, 2018, 11:11:48 AM »

Josh
My only comment is that I never touch the stab on catapult gliders. I think Jim Buxton was the source of that info for me. If I remember correctly his reasoning was that any adjustments to the stab will have greatly magnified effects at launch speed.

For heavy gliders in typical low ceiling sites this may not be a big concern but it is a rule that I follow.
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Maxout
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« Reply #58 on: November 19, 2018, 01:29:50 PM »

Josh
My only comment is that I never touch the stab on catapult gliders. I think Jim Buxton was the source of that info for me. If I remember correctly his reasoning was that any adjustments to the stab will have greatly magnified effects at launch speed.

For heavy gliders in typical low ceiling sites this may not be a big concern but it is a rule that I follow.

Since I'm flying a model with a fixed wing mount and pultruded carbon fuse, that's not really an option, but I'm really curious what he's using instead. On outdoor gliders I use gurney flaps on the stab and rudder and the adjustments hold for years without significant changes. Jim is in a different league from me anyway...I couldn't replicate his stuff if my life depended on it!
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jdpsloflyer
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« Reply #59 on: November 19, 2018, 02:18:24 PM »

I like the explanation Olbill had in 2013, I used that learning and coaching my students.

My standard system:

Adjust the glider for the best glide.
Throw hard straight ahead and observe.
If it dives add incidence, retrim the glide and repeat
If it has a steep climb remove incidence, retrim the glide and repeat.
When you have a level flight that slows down into a normal glide OR a slight climb and good transition to the glide you're ready for catapult testing.
Go slow at first with low power and a shallow launch angle.
Increase power and launch angle in small steps and watch what the glider does at the top of the climb.

I always set up low ceiling gliders for a right turn in the glide and launch with a right bank. The amount of bank and the launch angle are both critical and need to be worked out with experimentation. If you're using my setup you will see one of 3 possibilities:

1. Everything is perfect. Fly it until the launch is committed to memory and then put it away.
2. The glider will be in a right bank at the top of the climb and lose altitude before it starts the normal glide or it will spin in. Use less bank.
3. The glider will stall at the top and either lose a lot of altitude or spin in to the ground. Use more bank or a shallower launch angle or both.

If the glider spins in when you think it shouldn't then add incidence. This will also call for more nose ballast so don't change it much. I always try more flap deflection as a first try when I need more incidence.

I think a lot of flap deflection gives a safer model because the flaps will give you more incidence in the glide. The WIF7 has about 1/4" of flap deflection.

As for carbon rods, I have experimented with adding a small pylon to the rod and one to the wing so we can move the wing a small amount for trimming purposes (both for CG and incidence).  This has proved to be easier than glueing the wing directly to the rod.  The trouble I am having is finding pultruded rods that are straight, ones that are slightly bent need to be aligned carefully to avoid yaw and pitch problems.  I'm thinking balsa fuselages are the way to go.


BTW what is a gurney flap?

Jerry
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DavidJP
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« Reply #60 on: November 19, 2018, 02:58:52 PM »

Came upon this topic by chance and much amused by the copyright issues.  Your laws on the matter seem rather different from ours in the U.K.  I like the “cease and desist” letter.  An example of lawyers fondnes for using two words when one will suffice. 

Copyright actions here are very very costly. 

My feeling is that my response would be two words.  Ascendo tuum. (Latin of course).

Forgive my intrusion.
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Maxout
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« Reply #61 on: November 27, 2018, 07:43:24 AM »

Came upon this topic by chance and much amused by the copyright issues.  Your laws on the matter seem rather different from ours in the U.K.  I like the “cease and desist” letter.  An example of lawyers fondnes for using two words when one will suffice. 

Copyright actions here are very very costly. 

My feeling is that my response would be two words.  Ascendo tuum. (Latin of course).

Forgive my intrusion.

Just as a follow up, a friend of mine who keeps a patent attorney on retainer got me a legal opinion and I updated the listing on my site accordingly. Bottom line is that "fair use" dictates that I can describe the product as complying with Science Olympiad rules for Elastic Launched Glider and there's nothing they can do to stop that. As a double layer of insurance, the listing also specifies that I have no affiliation with Science Olympiad. And I haven't heard anything further from SO on the issue.

Most importantly, though, kids are flying the Protege gliders and having fun with them, which was the whole point anyway. The carbon fuselages seem to be the way to go on these models. Extremely durable.
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DavidJP
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« Reply #62 on: November 28, 2018, 09:16:26 AM »

That seems sound enough. But  in any event their loss or damage could not be very much at best so the costs alone (US Lawyers  to cheap either) would be prohibitive?  I have known a few folk who think mention lawyers and everyone will cower.
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wlsguy
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« Reply #63 on: November 30, 2018, 08:07:08 AM »

You may want to reconsider use of the word “Olympiad” not because of a copyright but because it’s exclusive use is restricted to the National Olympic Committee by the Amateur Sports Act. Science Olympiad got special permission for its use after they were contacted by the lawyers.- John, Guru Engineering Tech
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