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Iridescent Wings
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« on: November 03, 2019, 03:03:28 PM »

So there's this thing about big HLGs that never work. I'm talking about the larger, heavier outdoor ones. Ones with 1/4" thick wings and dethermalizers. Whatever I do I cannot get them to fly! If it helps I'll share what I do:

Cut out a wing blank from the lightest 1/4" wood I can find. I sand the outer edges nice and smooth before glueing a basswood strip to the LE. Then I start the airfoil, planing away wood starting at the TE and working my way up to the high point. Then I get out the sandpaper and sand it all smooth, as well as get the wood as thin as specified on the plans to create whatever airfoil specified. Once the TE of it all looks right, I put in the LE shaping and start to smooth the whole wing out. The wing usually looks satisfactory by now so I cut the wing up and jig it and whatever for dihedral. I give the finished wing a nice smooth-over sanding again and put it aside for the rest of the plane.

Honestly that's all I'm going to share because the fuselage is literally a super tough stick and the tail is just thin wood lightly rounded and airfoiled. I assemble it as according to the plans and it won't fly.

Then for some examples of flight characteristics, it'll sometimes just roll upside down, maybe stall and fly backwards, and in some rare cases it will tumble through the air like a brick.

Any help would be appreciated!
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flydean1
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« Reply #1 on: November 03, 2019, 06:02:44 PM »

Pictures are worth a thousand words.
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USch
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« Reply #2 on: November 03, 2019, 06:14:04 PM »

Sounds like a CG way back from where it should be.

My 2 cents worth...

Urs
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lincoln
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« Reply #3 on: November 03, 2019, 06:33:04 PM »

It sounds like it might be,cg to me as well. Possibly only a bit too far back, since hlg's are often just barely stable.

Maybe your throw is a problem. The elevation,angle and bank angle you throw at are important. With sidearm/discus,l launch, the,yaw angle at release is important too. Too much yaw could make the model roll over.You could call it lead or lag instead of yaw angle.

It would help if you told us whether this is sidearm/discus launch or overhand. It would also help to see the plan you're building from.
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Iridescent Wings
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« Reply #4 on: November 03, 2019, 06:56:37 PM »

A few answers to those:

-Yes, the glider is balanced with clay to what the plans say or until it "works", if you know what I mean.

- Pictures of the plane are actually unavailable right now because mine is on the roof =P

- I throw overhand for the ones with lower aspect ratios, which I fly a lot because they are easier to store and I prefer R/C if I fly with a DLG launch.

I can get a photo of the plans I use, but the resolution is terrible =(
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Iridescent Wings
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« Reply #5 on: November 03, 2019, 07:01:16 PM »

Never mind, I got it down. It's the Yellowbird 13. It's not quite as big as the ones I previously spoke about that I have but you get the idea:

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lincoln
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« Reply #6 on: November 03, 2019, 08:35:05 PM »

Maybe you need to put in just a bit of up elevator with a bit more nose weight. Won't hurt much to try.
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Iridescent Wings
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« Reply #7 on: November 03, 2019, 08:38:12 PM »

Maybe you need to put in just a bit of up elevator with a bit more nose weight. Won't hurt much to try.

This one is trimmed, I'm just using it to set the stereotype of plane that I'm talking about. Thanks though :-)
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lincoln
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« Reply #8 on: November 05, 2019, 06:32:32 PM »

I guess I don't  understand. If the model was "trimmed", it would fly right. But you've been telling us about gliders that don't fly right.
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Iridescent Wings
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« Reply #9 on: November 05, 2019, 07:33:58 PM »

I guess I don't  understand. If the model was "trimmed", it would fly right. But you've been telling us about gliders that don't fly right.
Exactly. It's just a picture for an example of what they look like. I find that the thicker the wing the less responsive the plane is to adjustments. This is a larger plane, but the wing is only made from 1/8" sheet. I used it because it is roughly the kind of plane that wouldn't fly because of the weird wing. One of the problems I had were good for an example for here. I was at the park some time ago with one of the heavier gliders. Test glides were super short since my house doesn't have much flying space so I thought it was all right. But as soon as I was out in the open, and could toss it a little harder, it started diving in. So I gave it a trim tab to correct this, yet it kept doing the spiral. I put in another tab next to it, but still nothing. I tried the other wing, putting it on to counter the diving spiral, but that made it stall. I gave it a bit of nose weight and down elevator in attempt to correct this but it dove again. So I took way the nose weight (since the launch was all right) but then it kept stalling.


I gave up and threw around a new glider after that because the wings were practically hairy from tabs and it just wouldn't behave =(
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glidermaster
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« Reply #10 on: November 06, 2019, 08:02:54 PM »

I am struggling to understand fully what you're saying here, but I built Yellow Bird 13 in the 1960's when I was about 10, and I got it to fly quite well, in fact it was the first good HLG I built on my own.
I have built well over a hundred HLGs since, including 2 dozen of this little 12" design. The best ones of this design weigh 12 to 15 grams. Up to 20 grams they still go OK, above that they start to deteriorate. I put together some kits for people, and I estimate about 70 have been built, so I know the design well!

I suspect weight might be the issue here. Many years ago my cousin Bill and I were flying at Chobham Common (UK) and were approached by a guy who had 2 beautifully built and finished scaled down Yellow Birds. From memory under 10" span (so, quite small models). They were very nicely built, but they weighed over 20 grams each. They flew somewhat as you describe.

Also attached is a picture of a recent HLG. It is 24" span (over 600mm) and weighs 30 grams. Wings are from 1/4" (6mm) thick stock where the basic sheet (36"x4" by 1/4" thick) weighed under 60 grams (say 2 oz.). The tail is from 1/16" stock (also 36"x4") weighing about 12-15 grams. The fuselage is from rock hard 1"x 1/4" stock weighing 40 grams.
Note that these quoted weights are for the raw unshaped stock wood.

John
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flydean1
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« Reply #11 on: November 06, 2019, 09:34:43 PM »

Suggestion:  Instead of whacking along rolling your own designs that may look OK to you, but may have some hidden design flaw, why not build something from a well engineered kit.

I recommend http://jhaerospace.com.  This is Josh and Hope Finn's website.  Josh posts here under the name Maxout.

He has a very comprehensive selection of gliders that he recommends for various skill levels.  He also produces video tutorials to help you build, and fly his designs.

I can recommend his glider kits without reservation.  This would give you a proven base line design which you can then branch out into your own designs as you increase in building and flying skills.

Hand Launch Gliders are deceptively simple-looking, but can be very frustrating.  I have walked in your shoes my friend.  Spare yourself more frustration, and give a couple of Josh's kits a try.
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Iridescent Wings
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« Reply #12 on: November 07, 2019, 05:31:52 PM »

Suggestion:  Instead of whacking along rolling your own designs that may look OK to you, but may have some hidden design flaw, why not build something from a well engineered kit.

I recommend http://jhaerospace.com.  This is Josh and Hope Finn's website.  Josh posts here under the name Maxout.

He has a very comprehensive selection of gliders that he recommends for various skill levels.  He also produces video tutorials to help you build, and fly his designs.

I can recommend his glider kits without reservation.  This would give you a proven base line design which you can then branch out into your own designs as you increase in building and flying skills.

Hand Launch Gliders are deceptively simple-looking, but can be very frustrating.  I have walked in your shoes my friend.  Spare yourself more frustration, and give a couple of Josh's kits a try.

Thanks for the suggestion, but me and Josh are actually great friends! I've built all of his 8" and 6" gliders as well as the OSG, OSW, and Sweepette Foamy. I've also built and flown all of his Protege series gliders and his K777 Ministick. I also fly his Noncents Pennyplane and this year's Senior Flyer. I don't design any of my own gliders though. The one plane that I simply can't get to fly was the Sweepette from Ron William's book. Obviously there's more than just one plane that won't fly than that, but it's the one I really want to fly. I am not a beginner to any of this though. I have roughly a year of nonstop work on building planes and gliders. However, I only have flown gliders with roughly 12" and 14" wingspans or less. Ask Josh, we both have flying gliders with 1" and 1/2" wingspans!
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