Requesting Help for Launcher and Flight Log

m_visswanathan
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Requesting Help for Launcher and Flight Log

Postby m_visswanathan » November 26th, 2015, 8:07 am

This is the first time I'm doing elastic launched glider and I have hit a problem. I cannot figure out how to make the launcher. In every instructional video I see, they always show a picture of a wooden dowel with a rubber band tied on. I have tried this multiple times, but the glider hits the wooden dowel every time it is launched.

How do I fix this problem and what is a simple launcher design that has worked for you?

I also had a question regarding the flight logs. I haven't found any information that has been very specific on the flight log so what variables do we need to put on our flight log for this year?

Thank you in advance.

jander14indoor
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Re: Requesting Help for Launcher and Flight Log

Postby jander14indoor » November 26th, 2015, 2:04 pm

If you are hitting the stick on launch, unless the rubber is tied in the middle of the stick, I suspect you have basic trim problems you need to solve before you worry much more about your glider.

How does your glider fly when hand launched? When hand launched from about shoulder height, straight and level, just a gentle push, it should glide slowly to the floor in a left turn, taking about 4-5 seconds to descend from shoulder height. If it doesn't, fix that first!

For a better launcher, I've seen a number of team make one from a meter stick with inclinometers on it to launch at consistent angles. Also good to have a handle. Meter stick should be flat, rubber attached on one side, handle the other. Inclinometers at convenient positions to read. Pull rubber back and launch glider off the top. Record pitch and roll and rubber stretch.

Hope that helps, turkey is calling.

Jeff Anderson
Livonia, MI

m_visswanathan
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Re: Requesting Help for Launcher and Flight Log

Postby m_visswanathan » November 26th, 2015, 4:37 pm

I know the glider isn't the problem, it is the launcher. The first few gliders I have made so far fly very smoothly when gently hand tossed, so I do know that isn't the problem. My old launcher design was a pen with a paper clip attached to it. The rubber band was in the hook of the paper clip and this worked very well. The gliders got in between 7-9 seconds almost every launch. I am building my gliders from scratch with no kits used. I'm using a basic plan that I found on the AMA Flight School website.
However, the pen launcher is easily broken and I think it doesn't meet competition standards. I have tried making a new launcher which is a wooden cylinder with a 1 inch diameter, with a hole drilled about 1/4 inch from the end. I then cut a rubber band, strung it through the hole, and tied it. However, the glider hits the wooden dowel every launch no matter what angle I use. I don't know if this isn't working because of the rubber band knot or the shape of the stick.

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Re: Requesting Help for Launcher and Flight Log

Postby jander14indoor » November 26th, 2015, 8:20 pm

Hmmm, still suspect something not right with the glider. When things are working right, the glider should be pulling well away from the stick by the time it gets to the end. At launch speeds your glider should be pulling up so hard it is nowhere near the stick.

See this picture: http://www.amaglider.com/?p=view&a=what ... ing-launch May be a little hard to see, but the glider is just passing the end of the launch stick and notice the rubber is almost 90 DOWN and the glider has already risen almost a foot above the end of the launch stick.

Note, the launcher can be VERY simple. AMA only allows a short six inch stick with the rubber attached to the end. A quarter inch hardwood dowel is pretty common. The experts make it work by LOTS of practice to get the angles right every time. The suggestion I made about a 'better' launcher is available to you as an SO flyer to control those critical parameters with less practice. I see one thing you are saying that concerns me. You don't need a hook on your rubber, some Event Supervisors might consider that unsafe. Never used in AMA flying. The rubber just hooks around a simple feature on your glider.

Another thought, where is your hook on the glider? How heavy is your glider? How high does it go on launch?

Jeff Anderson
Livonia, MI

m_visswanathan
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Re: Requesting Help for Launcher and Flight Log

Postby m_visswanathan » November 26th, 2015, 9:18 pm

My glider's hook is on the very end of the fuselage. The glider doesn't have a metal hook on it, but the pen launcher I was discussing earlier had a paper clip and that paperclip acted like a hook for the rubber band to sit on. The gliders I build average around 4-5 grams, and can reach a height of 25-30 feet when launched at a 33-35 degree angle. Is it possible to maybe send a link or give a tutorial on how to make the launcher so I can compare it to what I did with my launcher?

And I thought I should mention that I have modeled the front of the glider after the Freedom Flight Model, so it looks almost identical except that the nose is a bit bigger.

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Re: Requesting Help for Launcher and Flight Log

Postby m_visswanathan » November 30th, 2015, 6:53 am

I was also wondering if logs could be typed or if they have to be handwritten when we present them to the event captain.

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Re: Requesting Help for Launcher and Flight Log

Postby bernard » November 30th, 2015, 1:04 pm

m_visswanathan wrote:I was also wondering if logs could be typed or if they have to be handwritten when we present them to the event captain.

As always, disclaimer that this isn't the place for official clarifications/opinions. The rules don't seem to prohibit typing flight logs so it should be allowed. It also doesn't specify that they need to be handwritten.
"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: Requesting Help for Launcher and Flight Log

Postby m_visswanathan » November 30th, 2015, 5:25 pm

Thank you.

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Re: Requesting Help for Launcher and Flight Log

Postby wlsguy » December 7th, 2015, 4:42 am

m_visswanathan wrote:This is the first time I'm doing elastic launched glider and I have hit a problem. I cannot figure out how to make the launcher. In every instructional video I see, they always show a picture of a wooden dowel with a rubber band tied on. I have tried this multiple times, but the glider hits the wooden dowel every time it is launched.

How do I fix this problem and what is a simple launcher design that has worked for you?

I also had a question regarding the flight logs. I haven't found any information that has been very specific on the flight log so what variables do we need to put on our flight log for this year?

Thank you in advance.

I posted photos of the launcher our team used successfully in Ohio when this was an event for High School.
It helps teams control the critical launch parameters.
Let me know if you have questions.

The tape measure on top is one of the free paper ones from Ikea (or you could print one).
The bubble levels are available from Menards
http://www.menards.com/main/tools-hardw ... ernal-mcom

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Re: Requesting Help for Launcher and Flight Log

Postby RobSNoVA » January 2nd, 2016, 2:29 pm

We taped the rubber band to the dowel (about an 1" or so in diameter, almost a broom stick) and then had the rubber band start from the back of the stick and go across the top and then down. This way, the rubber band wanted to lift a bit. Also, we have the top of the stick (where the rubber band is attached) angled towards the person, not away.

Regarding the logs. NOTE: each glider needs its own log. Yes, you can print each log as a single sheet for each glider. Off the top of my head, I believe that you can pick your own variables, but please double check, some might be mandatory, some optional. Here are common ones:
* Time of Flight
* Maximum Height (from the floor) (Max < Height of ceiling ;-)
* length of elastic (i.e. how far you pulled it back)
* launch angle from horizontal (pitch)
* launch angle roll (from vertical, i.e. the glider wings are not level. some people like to use roll, some never use roll)

Note: we used hand written logs in a bound note book for elastic launch glider and typed logs for air trajectory.

good luck
Rob

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Re: Requesting Help for Launcher and Flight Log

Postby retired1 » January 6th, 2016, 7:03 pm

According to high speed video that Bill Gowan did (he holds several indoor glider and rubber band records) it is not hitting the stick, but the snap back of the rubber band is hitting the wing.
In my opinion, based on seeing last years state event, a launch stick made out of a 1 x 2 smooth wood of a desired and legal length is the answer. Glue a couple of inches of the wood on the underside of the 1 x 2. Now take and round over the end. A bench sander really helps. You will end up with about a 1.5" curve . Attach a dowel or stick to the underside for a hand hold-- probably about 1/4 of the way back from the launch end. Move as desired. You can attach the rubber band in any number of ways to the bottom side of the curved nose block--I would guess about an inch or so back.
This device makes it far easier to establish a vertical and a rotational angle for you launch. It is also far more repeatable than a plain dowel. You can add all kinds of bells and whistles but they might not do much good unless you practice a lot!!

m_visswanathan
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Re: Requesting Help for Launcher and Flight Log

Postby m_visswanathan » January 16th, 2016, 8:17 am

Thank you everyone for helping me very much.

I finally figured out a launcher that works so thank you for helping me out.


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