Elastic Launched Glider B

[Bilbo McSwaggins]

I saw on one of the Launched Glider videos that an "accelerant" is used to dry the CA glue much more quickly. Does anyone know where I can buy that (without having to order and wait since we are in a bit of a rush?) I thought they said it is sold at Walmart, but I couldn't find it there. And are there any types that are preferred?

Honestly I don't use accelerant when I am building my gliders as it forms a more brittle joint, but for field repairs, I use B.S.I Smith that I put in a bottle with a brush cap. You can get accelerant at most hobby shops.

[bernard]

I saw on one of the Launched Glider videos that an "accelerant" is used to dry the CA glue much more quickly. Does anyone know where I can buy that (without having to order and wait since we are in a bit of a rush?) I thought they said it is sold at Walmart, but I couldn't find it there. And are there any types that are preferred?

Honestly I don't use accelerant when I am building my gliders as it forms a more brittle joint, but for field repairs, I use B.S.I Smith that I put in a bottle with a brush cap. You can get accelerant at most hobby shops.

We have a Hobby Town near us that sells it, and Michaels might sell it (though I don't think they do). I've read somewhere that baking soda works as an accelerant, so you could try that. I usually don't use accelerant unless there is a glue crust that prevents it from bonding quickly.

[P2P]

The glider we have built for the competition glides pretty smoothly (very minimal stalling), but glides faster than we would like it to. Is there any way to slow the glider down?

[fifty_missions]

The glider we have built for the competition glides pretty smoothly (very minimal stalling), but glides faster than we would like it to. Is there any way to slow the glider down?

My first question is how much does it weigh? A 6 gram glider will fly much faster than a 4 gram glider. The 6 gram glider will also take more airspace to make its transition. That is after making the apex point of the launch at the ceiling, it will come downhill to gather enough airspeed to enter the glide thus losing 20-30% of the usable altitude. Sand the wings, stabilizer and fin aft their midlines (middle of the surface from tip to root) and remove any amount of material that allows the surface to be less than 1/32" thick (and translucent).

In addition on your glider-
1) Try removing small increments of clay in consistent "small bits" and test fly until the glider stalls. Add the last little increment of clay. Note this that nose heavy gliders always fly stable but fast. Closer to the stall allows better transitions and slower descents.
2)Try bending the trailing edge of the stabilizer up 1 mm. This should bring the nose up and slow the glider in the glide.
2) If it does enter the stall, add some clay to the nose to minimize that stall.

Overall lighter will always fly slower.

Good Luck,
50 Missions

[Bilbo McSwaggins]

The glider we have built for the competition glides pretty smoothly (very minimal stalling), but glides faster than we would like it to. Is there any way to slow the glider down?

My first question is how much does it weigh? A 6 gram glider will fly much faster than a 4 gram glider. The 6 gram glider will also take more airspace to make its transition. That is after making the apex point of the launch at the ceiling, it will come downhill to gather enough airspeed to enter the glide thus losing 20-30% of the usable altitude. Sand the wings, stabilizer and fin aft their midlines (middle of the surface from tip to root) and remove any amount of material that allows the surface to be less than 1/32" thick (and translucent).

In addition on your glider-
1) Try removing small increments of clay in consistent "small bits" and test fly until the glider stalls. Add the last little increment of clay. Note this that nose heavy gliders always fly stable but fast. Closer to the stall allows better transitions and slower descents.
2)Try bending the trailing edge of the stabilizer up 1 mm. This should bring the nose up and slow the glider in the glide.
2) If it does enter the stall, add some clay to the nose to minimize that stall.

Overall lighter will always fly slower.

Good Luck,
50 Missions

Also, If you are using a flapper design, bend the flaps down.

[Bilbo McSwaggins]

The glider I'm working on isn't transitioning well. I'm using a flapper design. I originally had problems with it nosediving when launched at a positive angle but I added ballast to the front and it doesn't happen anymore. I think it isn't dealing well with the fast launch speeds. Has anyone else had issues with this?

Usually when that happens, I simply increase the dihedral between the two wings by applying acetone(Nail polish remover also works since it has acetone in it) the joint between the wings and gently bend the wings upward to coax the wings into a bigger dihedral. A bigger dihedral has more stability, bet will be generally less aerodynamic, while a smaller dihedral will have less stability but improved aerodynamics. Hope this helps!

[fifty_missions]

Be cautious with adding too much dihedral.With too little dihedral the glider is unstable in the roll axis and will continue a roll once it enters until it hits the floor. With too much dihedral, the glider essentially becomes an arrow. Like an arrow, it will fly in a straight path with a similar trajectory and at higher speed.

What any glider needs is a some dihedral but not so much that it overrides the effects of the fin/rudder and stabilizer/elevator. It is VERY IMPORTANT that the glider be just unstable enough to transition from its ballistic launch (high speed, semi-vertical) into a stable, horizontal glide with lower speed. Too much dihedral will not allow this to happen until most of the glider's altitude is consumed while coming downhill from the launch apex. This is contrary to what you want which is to transition into the slow glide as close to the apex as possible.

Keep the dihedral moderate. For wings- 1" at each wingtip and up to 1-1/2" at each wingtip will be sufficient for most gliders the weigh 5+ grams. The dihedral can be slightly less if the glider weighs less than 5 grams.
http://en.wikipedia.org/wiki/Dihedral_%28aeronautics%29

BTW, with too much dihedral you effectively reduce wing area which is projected or like looking at the wing in a top-down view. This means that the lifting surface is reduced when using excessive dihedral. An important ratio is wing loading which the relation of how much area of lift a wing has vs. how much mass it must support.
http://en.wikipedia.org/wiki/Wing_loading

In essence, the more dihedral you use, the less wing area there is to lift or support the glider. For that glider to continue flying, it must fly faster to stay aloft. Increasing the speed in the glide will shorten the flight while reducing the glider's ability to orbit (maneuverability) and that simply means last place in the competition.

Regards,
50 Missions

[JonnyL]

What would be the best design to use for a glider? Does anyone have recommend a design to use?

[bernard]

What would be the best design to use for a glider? Does anyone have recommend a design to use?

From what I've heard, design is not as important as other things such as build quality and weight. That means you can probably take any design off the internet and replicate it. How well a gliders is adjusted makes some teams have excellent times and others have not so excellent times even when they are using the same kit and both follow the instructions correctly. Of course, if you use a kit and don't follow the instructions correctly, your glider probably won't turn out as well.

Here's what the Elastic Launched Glider CD says for priorities:
"1 Build quality/trueness/straightness
2 Strength
3 Weight
4 (and a distant number 4) Design"

[P2P]

So... we (my partner and I) decided to rebuild some of our gliders from scratch. We focused on keeping them light and they glide really slow now! But one of our gliders seems to work perfectly when handlaunching it, but has a few problems when we launch with the elastic.

First, the glider seemed to nosedive a lot, but I think we got that fixed from the wiki's troubleshooting page.
Next, the glider would seem to stall every time it slows down a lot (about every 10-15 seconds), it is a very small stall so I was just wondering whether it is really worth to fix it while having the rest of the glide become a little faster.
Last, and the biggest problem, we have one glider that never stabilizes and stays in the angle of the initial wing bank (about 45), we have tried to adjust the wing bank, but it doesn't seem to affect it until we launch it almost totally flat. This problem leads to the glider making a very fast arc towards the ground. While this glider does not have to be used in the competition, I would preferably like to use it because it has a very slow descent.

Thanks!