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Author Topic: 12" Catapult Launched Gliders  (Read 2697 times)
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dosco
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« Reply #75 on: September 29, 2021, 07:57:48 PM »

Dave:
 I've never cut Pampas grass this early in the year, while the foliage is still green. So I wouldn't know if it would be strong enough green to use right away. There is an inter-pith that  is soft and spongy until it is dry. Maybe you could harvest some green and compare it to some of what you have.

So you normally cut it after it's dried and brown, if I understand correctly. I'd speculate it's best when dry.

Yes, I noticed the pith in the pieces you sent me. I've cut some of the stuff I've seen and looked specifically for that feature. There are some stands I pass when riding my bicycle that I need to investigate.

The pith, IMO, is vitally important to both strength and stiffness.

If I had some space (I don't) I'd consider hanging the stuff upside-down.

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It's a little over 6 feet of 1 1/2" lead bathroom sink waistline and it weighs about 30 pounds. Approximately 2 g of ballast for a catapult launched glider, that's roughly 6000 gliders.
I could mail anybody some lead if they want some. You just have to pay the postage :-)

The trick with lead is to use the flat rate packages(!).

I have a piece of copper sewage pipe that I've used for noseweight ... cut a piece, flatten, and glue it on.

Best-
Dave
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stupid
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« Reply #76 on: November 19, 2021, 10:38:38 PM »

  We had an unusual day in Denver this morning, no wind, 69° absolutely no drift while flying my gliders.

  Arrived at the park this morning about 10 AM and started trimming a glider that I had repaired, and after doing some test gliding and trimming, I gave it the full power launch. It was back in trim and flying well with 45 second flights. On the third launch my adjustments crept out and did a wing over to the right crashing into six pieces, hitting the pavilion at the edge of the park. Oh well, no big loss. The stabilizer had so many cracks and so much cyanoacrylate glue on it from fetching it out of trees.

  Decided to fly the last remaining 12 inch Stinger Glider and had 2 more flights of over 1 minute 23 seconds, all circling straight overhead and landing within the 50 foot circle that a glides in. Warm enough to have extended flights but no thermals drifting over the grassy park. Then at about noon. It started to get breezy and called it a day before I lost it in the pond that the wind was blowing it to.

  I thought I would describe my trimming procedure that might help others trimming their gliders to keep them from crashing them right away.

  Before starting visually inspect the glider from the rear to make sure that there are no visible warps.

  The first step is to test glide into the wind at the assumed gliding speed to see that it's not diving in or stalling & has a slight turn at the end of the glide. We all know this. After you have made adjustments, if any are needed you proceed on to the next step.

  The second step is to find out if you have any warps that are not visible. This is the part that isn't mentioned in a lot of trimming descriptions, and if you try a full power launch without doing this procedure you have a good chance of ruining your glider.    With your catapult launcher, launch the glider straightahead with a slight nose down attitude with level wings under very low power, may be stretching the rubber band back 2 to 3 inches. This is where you will discover if you have any warps that aren't visible and it will be under low-power so your glider will probably survive if it does have any warps. You're looking for a pattern that starts to rise up and transitions into the glide without stalling and then turning into its circle. I'm going to skip all the minutia on how to correct an off pattern, as it gets very wordy and confusing trying to describe everything that could be wrong. Once you've made any adjustments, you're ready for first full powered flight, assured that you will not ruin your glider on the first launch.

   Now all that you need to do is adjust the amount of wing bank and launch angle to get the transition that you want. Finally,  fine tune the center of gravity for the best glide. I usually end up adding a small clump of poster putty just in front of the stabilizer on the fuselage. When I return home I will check the center of gravity and Mark it on the wing. Then remove the poster putty and excess nose weight until it balances at the center of gravity that I have marked. I think you can see the poster putty on the glider if you enlarge the photo.

  Flying gliders without dethermalizer's is a lot of fun, but you do go through a lot of gliders watching them fly out of sight. It does give you a lot of experience on trimming them to fly.
             All the Best           Bob
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Re: 12" Catapult Launched Gliders
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esmerejon
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« Reply #77 on: November 20, 2021, 04:16:14 PM »

Bob,

I certainly share with you those sensations so characteristic of our little gliders. Sometimes I even wish I could fly something that didn't have such brutal speed changes and could be done with higher wing incidence. But then, with a bit of luck, the miracle happens and all physical forces are in harmony and magic happens!
Sometimes I think that we are a bit like gamblers, the most exciting thing is precisely that you are never quite sure if you will be able to fly!
This addictive feeling is precisely what keeps me in free flight when I've been in the RC my whole life, I guess I got bored that things were so predictable.

Damn little gliders!

Thank you for your help in our fight!
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« Reply #78 on: November 22, 2021, 08:24:32 PM »

Hi Stupid,
Your creative build-mind, ideas, and  refinements are remarkable. You are such a credit to this hobby. Thank you for sharing your visions, hard work and enjoyment. Your photographs add so much to your text messages.

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« Reply #79 on: November 23, 2021, 07:51:57 AM »

Thanks so much for the compliments. I find that the ability to post photos on this forum is what makes Hip Pocket Aeronautics more enjoyable for me. I was always a visual learner and when I would see photos of the finished airplane. I would always wonder how they did it. The photos give  good insight to the building process, if there included.

            All the Best   , Bob
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