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Author Topic: Beginner HLGs  (Read 1501 times)
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Art356A
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« on: December 21, 2015, 11:18:15 PM »

I kinda felt that my arthritic shoulders were healed enough to try out on useful pursuits, so I bopped out to the craft store last night for some lumber. I got some hard 3/16 for John Barker's Misguided Missile's fuselage, a sheet of the hardest 1/8 I could find for the Perryman Little Whistler, and found a nice sheet of 5.6 lb 1/8 for the wings of both. The Whistler calls for 1/8 x 1/2 spruce for the fuselage, but I had none, so I figured I'd try real hard balsa. An alternative might have been two sticks if 1/16 bass, laminated, but I counted that out.

I built the MM first, and tried it out in 16 mph winds, which have prevailed around here for the last 10 days or so. As with any Barker design, she flew nicely right off the bench. Good designer.

The Whistler was a different case. Initial alignment was a challenge, but I got past that, got it together and got out into the wind. It flew foul, all Dutch roll and oscillations, and nosedived into the turf once it lost airspeed. I figured I'd take out some noseweight, as the MM balances at the wing's TE, and the Whistler plan shows the CG 1.5 inches forward of that. Must be a misprint. Took out some noseweight but it didn't help. Turned out the problem was that I had neglected to add the 1/32 shim under the back end of the tailplane which provides about 1½º of decalage. (I gotta learn to read the small print.) Did that, restored the noseweight to the plan CG and it was all tamed. Then after a few nice glides, a test glide ended in a bush, which broke the fuse into 4 pieces. I still lacked 1/8 spruce, so I had to put whatever was around into service for the rebuild (picture 2).

Got it back together, but it was way after dark, so all I could do with it was test glides to the bed. NG. It's a bit tailheavy, but still nosedives into the bed. I'm hoping that's because I couldn't get up enough airspeed. They're forecasting only 10 mph tomorrow morning, so I'll be able to try it in its natural environment.

The third pic shows them both, but what doesn't show is that they're both exactly 12.5 grams, despite the huge disparity in wing area, and the Whistler may still need more noseweight. I have spruce, but it's a big log (scrounged years ago from Steinway Piano rejects). I'll see if the guy across the street, who's a high class furniture builder, can shave me off a 1/8 sheet. That ought to knock a few grams off. 

a.
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My arms are so weak, it's like that pushup I did last year was a total waste.
Olbill
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« Reply #1 on: December 22, 2015, 12:45:30 AM »

Art
I think I ruined my shoulder throwing HLG's when I was 18. No way I would do it again.
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Maxout
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« Reply #2 on: December 22, 2015, 07:37:07 AM »

Art,

 I pretty much gave up javelin launch a long time ago. Fun but painful and unhealthy. Stan's DLG kits are a great source of something that won't injure you. Just like swinging a golf club. I'll even build you a composite wing for one. Wink

 I had very good success with the straight winged version of the Whistler. An outstanding flier when scaled down to 8"; about 60 seconds in dead air from catapult launch.
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Hepcat
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« Reply #3 on: December 22, 2015, 07:45:16 AM »

Art,
It is interesting to see the old MIssguided Missile after all these years.  It was actually a big change in English 'chuck gliders'; previously they usually had 'V' dihedral, swept back wings, a short moment arm and a forward CG and were thrown holding the fuselage between thumb and finger.  The 'MM' was the first to have a throw tab under the wing and a rearward CG to match the long moment arm and big tailplane.
To save your arm I am told it catapults very well because of the thin wing.  I don't know what happens to the fin if you try that.  I think somebody took the fin off and 'V' dihedralled the big tailplane which probably was a good idea.

John
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John Barker UK - Will be missed by all that knew him.
Art356A
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« Reply #4 on: December 22, 2015, 08:43:04 AM »

IT FLEIGELS !!!!

A bit tail-heavy, so not much of a glide, but on this flight it didn't need any.

I'll probably convert them both to cat launch once they're dialed in. As for my arm, Krempetz need not fear me.

a.

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My arms are so weak, it's like that pushup I did last year was a total waste.
Art356A
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« Reply #5 on: December 22, 2015, 09:10:53 AM »

Another .9 gm on the nose fixed the glide. It's now long, flat and floaty, but fast.

I tried a few tip launches, but they just yield snap rolls into the turf.

a.
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My arms are so weak, it's like that pushup I did last year was a total waste.
shuyge
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« Reply #6 on: December 28, 2015, 12:55:21 PM »


I tried a few tip launches, but they just yield snap rolls into the turf.

a.


Art,

Everything that I've gathered so far on tip launching indicates a completely different trim for the airplane.
My thread below about what to do with old javelin launch gliders goes through most of what needs to change.

Best of luck,
Stan
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