Elastic Launched Glider B

brianv
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Re: Elastic Launched Glider B

Postby brianv » March 15th, 2015, 10:13 am

Is there an advantage to a long launcher with a pistol grip handle on the bottom as opposed to a simple stick? Thanks in advance.

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Re: Elastic Launched Glider B

Postby wlsguy » March 16th, 2015, 8:13 am

brianv wrote:Is there an advantage to a long launcher with a pistol grip handle on the bottom as opposed to a simple stick? Thanks in advance.


If the launch handle has gages or indicators for pullback distance, elevation (up/down angle), and pitch (left/right angle) then yes, it has an advantage.
If not, then probably no.

That being said, not everyone needs an elaborate angle / measurement system to be successful. Launching is a lot like a golf swing, if you can do consistantly, you have good results, if not, you end up in the water sometimes.

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Re: Elastic Launched Glider B

Postby homesciencenerd » March 19th, 2015, 3:01 pm

In most competitive states, what would be a top 5 time
juanton out

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Re: Elastic Launched Glider B

Postby Bilbo McSwaggins » March 22nd, 2015, 5:22 am

1nxtmonster wrote:Soo...


Would it be legal to build a launcher that rests on the ground?

I'm pretty sure the 2013-2014 National champion had a launcher that rests on the ground.
Do not take life too seriously. You will never get out of it alive.
-Elbert Hubbard
On the bright side, my events this year are: Anatomy, ELG, Solar System, and CJAP :D
Medal Count:16

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Re: Elastic Launched Glider B

Postby jander14indoor » March 22nd, 2015, 9:31 am

Careful, while last years launcher was on the ground, rules changed. I don't have my copy handy so I don't know if it is directly legal, but with the 1 m length limit, hard to build like that now.

I supervised a contest this weekend. Two teams had long launchers with angle gages, they had a very consistent launch. The winning team had none of that, but had obviously worked hard to become consistent. The launcher very obviously managed their body position to have a consistent elevation, and their partner lined up behind and corrected the bank. Dead consistent launches, probably less than 3 ft variation in peak height. And their glider was well trimmed, out of 5 launches, only one had a little drop, less than 3 ft, during the transition.

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bernard
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Re: Elastic Launched Glider B

Postby bernard » March 22nd, 2015, 11:35 am

jander14indoor wrote:Careful, while last years launcher was on the ground, rules changed. I don't have my copy handy so I don't know if it is directly legal, but with the 1 m length limit, hard to build like that now.

I supervised a contest this weekend. Two teams had long launchers with angle gages, they had a very consistent launch. The winning team had none of that, but had obviously worked hard to become consistent. The launcher very obviously managed their body position to have a consistent elevation, and their partner lined up behind and corrected the bank. Dead consistent launches, probably less than 3 ft variation in peak height. And their glider was well trimmed, out of 5 launches, only one had a little drop, less than 3 ft, during the transition.

Jeff Anderson
Livonia, MI

It's in rule 3.g.. "1 m long in any orientation at launch" still seems like a lot of space to make a ground launcher.
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Re: Elastic Launched Glider B

Postby Bilbo McSwaggins » March 27th, 2015, 7:01 pm

wlsguy wrote:
N1njA_DuDepic wrote:I think freedom flight models are the best.


Based on data from Nationals for the past 2 years, there is no "BEST".
Of the 60 teams at Nationals, Freedom Flight Models have finished as high as 5th and as low as 59th. They are distributed in a normal pattern throughout the rankings.

The key points are:
1) Build consistent- Too many models were sloppy or had warps or issues which limited performance
2) Practice- If you expect to build a model and suddenly win, you are mistaken. This is not a contest of who can build the best glider. Taking and using data to improve your launch technique is what wins or loses competitions
3) Build Light- As with all of the flying events, if everything else is the same, the lighter glider will win. Just one word of caution, if you build so light your glider breaks every time your practice, your data or glider will have the issues from 1+2 above and you will perform poorly.

Thanks,
John Hance


But you can't build too light because the glider will not be able to go any higher after a certain height.
Do not take life too seriously. You will never get out of it alive.
-Elbert Hubbard
On the bright side, my events this year are: Anatomy, ELG, Solar System, and CJAP :D
Medal Count:16

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Re: Elastic Launched Glider B

Postby Bilbo McSwaggins » March 29th, 2015, 7:56 am

Just wondering how to determine the quality of the foam flaps. (I use freedom flight) :D
Do not take life too seriously. You will never get out of it alive.
-Elbert Hubbard
On the bright side, my events this year are: Anatomy, ELG, Solar System, and CJAP :D
Medal Count:16

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Re: Elastic Launched Glider B

Postby fifty_missions » March 29th, 2015, 8:23 pm

Just a quick report on the Indiana State Finals. The ELG event was held in the Mellencamp Fieldhouse with a height of 60'. Thomas Jefferson MS won with all5 flights in excess of 38 seconds EACH. Their total score for 3 flights was 112. The second place team was 72. TJ would have won the event with just two flights. Thomas Jefferson won the overall IN State Competition and will be flying at Nationals in Nebraska (60' ceiling).

They did not use the Freedom Flight design as that design has too many inherent issues. These include the following-
1) It is essentially short coupled and the fuselage is too short with the wing's trailing edge too close to the stabilizer which makes the model very pitch sensitive (nose up, nose down)
2) With the fuselage is so short, many have not passed the go-no-go gauge length inspection as they have a tendency to bow slightly shrinking the length. Those teams get tiered below all others.
3) The foam has tendencies to warp.
4) The FFlight design works best under 30' but cannot climb any higher. Height is everything in this event.

Instead, the TJ team have been using a format that they developed based on the AMA Educational Videos as well as the AMA Glider website. Their glider was in the neighborhood of 5 grams, an all balsa model, with a fuselage at about 37cm long, wings in polyhedral format at 32 cm span. The longer length allows the tail surfaces to be slightly smaller than those on the FFlight version with just enough stability to handle the high velocity launch yet just unstable enough to allow a transition with minimal altitude loss. See similar model in the picture below-

Here is the video that helped them the most...

http://amaflightschool.org/diy/2015-sci ... nch-glider

Regards,
50 missions (and counting)
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Re: Elastic Launched Glider B

Postby fifty_missions » March 29th, 2015, 9:06 pm

The Freedom Flight design has short coupled fuselage. That's ok if you have 20 years experience in trimming gliders. I highly recommend building a new fuselage that is more like 35-36 cm long. In addition,
try sanding the tail surfaces so that the trailing edges are about 1/64" thick. Another trick is to check the incidence relationship between the wing (positive) with the leading edge about 1/2 a degree higher than the trailing edge. If you can manage to do the reverse on the stabilizer (negative) with the trailing edge 1/2 degree higher than the leading edge you will have a glider with a good set-up for launching and transition.

Light weight is extremely important. Build the glider just under 4 grams and with the clay ballast you should be just over. The thinner trailing edges in the tail surfaces will allow you to tweak some trim. To bend in UP elevator, pinch the wood on the the trailing edge of the stabilizer and bend the wood up no more than a degree (about 1 mm). You can use the same method to add more or reduce the turning orbit by bending the trailing edge of the fin (rudder adjustment).

There are more issues but I always recommend starting the glider with a stalling flight pattern. You can either add more mass on the nose or reduce the UP elevator. BTW, NEVER add down elevator!!

Good Luck,
50 Missions

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Re: Elastic Launched Glider B

Postby Bilbo McSwaggins » March 30th, 2015, 6:43 am

This may sound stupid, but I am building a 80 cm. launcher and can't find any printable rulers that I like. :oops: (they are all too small or hard to read)
Do not take life too seriously. You will never get out of it alive.
-Elbert Hubbard
On the bright side, my events this year are: Anatomy, ELG, Solar System, and CJAP :D
Medal Count:16

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Re: Elastic Launched Glider B

Postby bernard » March 30th, 2015, 7:14 am

Bilbo McSwaggins wrote:This may sound stupid, but I am building a 80 cm. launcher and can't find any printable rulers that I like. :oops: (they are all too small or hard to read)

Could you cut a meter stick or yard stick and use that in your launcher?
"One of the ways that I believe people express their appreciation to the rest of humanity is to make something wonderful and put it out there."

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Re: Elastic Launched Glider B

Postby fifty_missions » March 30th, 2015, 8:34 am

Bilbo McSwaggins wrote:This may sound stupid, but I am building a 80 cm. launcher and can't find any printable rulers that I like. :oops: (they are all too small or hard to read)


What will be the height of the flying site? if this is to be a hand-held launcher, I would recommend using a meter stick cut to the 80 cm (why that particular length?) but would recommend attaching a strong handle. I have witnessed some launch failures due to teams struggling with trying to hold the bare meter stick.

Use that cut-off section of the meter stick for the handle's parts. Start with the inside portion of a laminated handle structure as it already matches the meter stick's thickness. Cut the end at a slight angle similar to a pistol grip angle. Cut two more longer pieces (pine or other hardwood NOT balsa!!) by at least 5 cm. These will be the two outside layers of the handle's laminate. Using 5-minute epoxy, glue the first lamination onto that center piece of the handle and let dry. Test fit onto the cut-down meter stick. Now, epoxy that half of the handle to the launch stick and clamp. When cured, epoxy the last side of the handle, clamp and let dry. When the assembly is cured (about 1 hour), drill small holes that go from the handle through the meter stick. Use some wood screws to secure the handle laminates. Do this from both sides (at least 2 per side). Trim any excess wood from the launch surface and sand smooth.

At the launcher's front tip, epoxy a piece of hardwood on the side with the grain perpendicular with the meter stick and 4X thicker than the screw eye shaft that you plan to use. Add wood screws to this as well when it is dry. The screw eye can be applied in parallel with the meter stick at the front end. this will be your attachment for your rubber loop.

I would also recommend not exceeding 1/16" cross section on the rubber loop. Any larger may induce a shock load of air on the front of the wings and cause damage. These lightweight gliders need a chance to have a graduated increase of speed before exiting the launcher. A loop made from a 12" strip (6" loop) is a good minimum size.

Midwest Products used to have a glider launcher- but it shows that it is "temporarily unavailable". Might be worth a phone call 800-348-3497

http://midwestproducts.com/products/tec ... r-catapult

Good Luck,
50 Missions (and counting)

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Re: Elastic Launched Glider B

Postby Bilbo McSwaggins » March 30th, 2015, 9:37 am

brianv wrote:Is there an advantage to a long launcher with a pistol grip handle on the bottom as opposed to a simple stick? Thanks in advance.

Other than having a more comfortable grip for your hand, there really isn't an advantage. :(
Do not take life too seriously. You will never get out of it alive.
-Elbert Hubbard
On the bright side, my events this year are: Anatomy, ELG, Solar System, and CJAP :D
Medal Count:16

Bilbo McSwaggins
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Re: Elastic Launched Glider B

Postby Bilbo McSwaggins » March 30th, 2015, 9:40 am

bernard wrote:
Bilbo McSwaggins wrote:This may sound stupid, but I am building a 80 cm. launcher and can't find any printable rulers that I like. :oops: (they are all too small or hard to read)

Could you cut a meter stick or yard stick and use that in your launcher?

I don't think that would fit because my platform for the glider is to thin and I don't actually want to put it on top since that makes it uneven.
Do not take life too seriously. You will never get out of it alive.
-Elbert Hubbard
On the bright side, my events this year are: Anatomy, ELG, Solar System, and CJAP :D
Medal Count:16


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