Elastic Launched Glider C

bjt4888
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Re: Elastic Launched Glider C

Postby bjt4888 » December 6th, 2013, 5:54 pm

Bizzle,
It is possible that your flap material is too stiff. I have found that thin .032" foam needs to be sanded on both sides to .025". See construction notes on the hip pocket aeronautics website for the WIF7.

Bjt4888
AMA member since 1972 (off and on)
NFFS member for many years (also off and on)

EmmaD
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Hi!

Postby EmmaD » December 9th, 2013, 4:11 pm

I did Glider last year, and for the most part our gliders worked, giving us a max of 15 seconds.
One of the struggles we had was getting the glider past a certain height for initial launch and getting it to transition easily. Also, our gliders would fly perfectly and then a week later nose dive into the floor and die, with us not altering them at all.

Can anyone explain the the possible problems we had and give a solution(s), especially the transition. We've started glider building again this year, and are having the same problems. Also rather confused on where wing is placed in relation to tail and nose... whats too close or too far?

The build for our glider had about a 2 inch wing chord, flaps/ailerons about 1 inch all along the trailing edge until the end when we had special wing tips... also open to new build ideas...

Sorry for so many questions! thanks!

musicalcoconut
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Re: Hi!

Postby musicalcoconut » December 10th, 2013, 7:53 am

This won't necessarily solve all the problems, but I think making a design without ailerons would help with consistency. Slight changes in ailerons can have a huge impact, and every time you do anything with the glider the ailerons could be accidentally changed. If you sand the wings thin enough, you can just bend the trailing edge to make adjustments without needing ailerons.

It's hard to know how to improve the transition without actually seeing the glider, but increasing the wing dihedral could help. Also, I'm sure you have tried launching a lot of different ways, but keep experimenting with that because although a lot of gliders can roll out ok with variations in launch, some gliders will completely fail unless they're launched exactly the perfect way, so you just have to find that perfect lauch angle.
2014 Graduate of Mounds View High School
National Medalist in Elastic Launched Glider (2013) and Dynamic Planet (2014)

wlsguy
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Re: Elastic Launched Glider C

Postby wlsguy » December 10th, 2013, 8:06 am

Your problem with not getting the glider high enough is likely cause by too much drag. I saw this when teams tried to use plastic film and foam. The additional drag would slow the glider and it would transition at a very low height (if at all). Your flaps (ailerons) and special wing tips all contribute to the drag on the glider. You need to reduce the drag by making sure everything is smooth and well aligned.

The second problem appears to be with repeatability. I’m assuming you can make several consistent launches on one day but when you try again on another day it performs poorly. One of two things happened; 1) you are not actually launching the same way. Minor changes in the method can make huge variations in the performance, or 2) your glider is warping or changing. I would rule out the launch technique first since it’s easier and very small changes in the glider (such as a warped wing) can be hard to see. Also make sure you don’t stack gliders on top each other. The one on the bottom will get bent by the ones on top.

Your question about where to put the wing: If you are using a plan, follow it until you get a flying glider and make minor adjustments after that. Since you already have a 15 second glider, use it as a starting point.

DrEvil
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Re: Elastic Launched Glider C

Postby DrEvil » December 12th, 2013, 7:15 am

So, any tips for gluing my stabilizer accuratley? I really need to work on getting the incidence correct. Are there any specific tools I probably should use?

Toast
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Re: Elastic Launched Glider C

Postby Toast » December 19th, 2013, 5:36 pm

Has anyone got a successful canard design? The center of gravity is really difficult to find...

bjt4888
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Re: Elastic Launched Glider C

Postby bjt4888 » December 21st, 2013, 5:36 pm

Dear Toast,
Here are some helpful links for canard design:

Canard design calculator
http://adamone.rchomepage.com/cg_canard.htm

Interesting discussion on the RCGroups.com forum “Canard Forum”
http://www.rcgroups.com/forums/showthre ... 6&page=114

There is also an interesting discussion of "Dutch Roll" on the RCGroups.com "Canard Forum". The discussion was related to configurations needed to minimize Dutch Roll tendencies, but as you may know, a certain amount of Dutch Roll tendency is desirable for free flight catapult launch glider transition.

Best result to date is about 19.5 seconds glide time from a canard based upon the Stan Buddenbohm Lit'l Sweep SO wing and with an adjustable incidence foreplane in the style of Stan's Category IV Lit'l Sweep wing mount. A more rigid foreplane mounting will probably improve performance, but the adjustable mount was necessary for testing.

Bjt4888

nxtscholar
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Re: Elastic Launched Glider C

Postby nxtscholar » December 23rd, 2013, 7:43 am

To be honest, I think most people are going to put off canard designs until after regions, or at least, until they achieve some satisfactory flight time with a non-canard design. After all, if I understand rule 5b correctly, the bonus is only present at the states and nationals level (why is that?)

But if I find something noteworthy, I'll share.

And on a side note, does anyone know any reliable vendors where I can obtain carbon fiber? :D

jander14indoor
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Re: Elastic Launched Glider C

Postby jander14indoor » December 24th, 2013, 7:22 am

You'll find things like increased challenges as you progress explicitly in several of the rules, and it is implicit in the actions of the ES who write one level of difficulty for regions, another for states and harder still for national tournament.

The idea among the rule writers is to allow a reasonable level of success open to many at regions, then assume you've demonstrated some level of proficiency if you made it to states so a harder task is needed to distinguish the best. By the time you make it to the National Tournament you are assumed to be highly skilled and an even harder task is needed to seperate teams.

Regards,

Jeff Anderson
Livonia, MI

fanjiatian
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Re: Elastic Launched Glider C

Postby fanjiatian » December 26th, 2013, 3:04 pm

Has anyone tried Stan's Lil Sweep kit in a lower ceiling, like 20 or 25 ft? The AMA website says it's optimal for heights around 30-40 ft so I was wondering
Has anyone bought one for 2014? I know he had one for last year but I'm not sure if he's changed it to match the shorter wingspan and higher mass requirement


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