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U-2 Dragon Lady

"A dance with a lady or a fight with a dragon" 117" span Jack Lynn Bale plan

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Chris Barlow01/10/2017 21:22:54
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1665 forum posts
1147 photos

Light tail! wink

If it needs weight in the nose that'll take the form of cocpit detailing and possibly a nice pilot and chair!

Wing cores are now cut ready for cutting the spars and wing tube in tomorrow hopefully.

Chris Barlow12/10/2017 23:18:41
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1665 forum posts
1147 photos

A bit done on the wings this week.

Foam cores cut in 2 sections with a hot wire. The root half is just over 50mm thick so a second piece of foam was added and glued to the lower section after cutting.

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Holes also bored out for the wing tubes with 22mm copper tube and 12mm Ali tube with a saw edge filed into the ends. Two 1/2" x 1/8" Spruce spars were cut into the foam top and bottom with a hot wire bent to profile and run down a straight edge. The spars sit alongside each other at the tip end and are glued into the cores with PU adhesive. When the Phenolic tubes are glued into the wing then will connect to the spars at the outboard end too.

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The skins are 1/32" Obeche and were cut to shape and taped together Making sure to produce 2 handed pairs. These were glued with a PU flooring adhesive. I use CaberFix D4 which is for chipboard flooring available from Travis Perkins and around £16 per big bottle.

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With 2 skins glued and the foam core sandwiched between them the core was weighted down with custom weights over 24 hours. In contact with air the D4 hardens in about 20 minutes but would still be wet between the foam and skin for a while longer.

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Same procedure for the second wing againg left for 24 hours to harden the PU inside. Once both wings were out of the moulds the edges were trimmed and sanded and are now ready to be lipped with balsa.

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You can see where the PU D4 has forced it's way through the joint in the skins and was contained by the packing tape used to joint the sheets. This is how the sheets are glued together on edge without actually gluing the sheets together! Also note the Obeche sheets are parallel to the leading edge on top of the wing and parallel to the trailing edge on the bottom of the wing to create a slight cross ply effect. Something I read about on a JP build blog I think!

john stones 112/10/2017 23:34:42
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8856 forum posts
1379 photos

Those look good Chris. yes

Chris Barlow12/10/2017 23:40:11
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1665 forum posts
1147 photos

Shed's full now though John! They're nearly 1.5m long and 440mm at the root each! The Fuzz is hanging above them at around 60" long!

laugh

Edited By Chris Barlow on 12/10/2017 23:40:57

Edited By Chris Barlow on 12/10/2017 23:41:23

john stones 112/10/2017 23:48:04
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8856 forum posts
1379 photos

Build it in your bedroom, she'll not mind. face 1

Chris Barlow15/10/2017 01:30:06
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1665 forum posts
1147 photos

Dangerous territory there John. She doesn't like it when I bring the toys in to cut decals for them on the kitchen table! surprise

A bit more done over the last couple of days. Leading and trailing edges glued onto the wings...

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And the beginnings of a tail plane. This too may go off plan as I might make it removable for storage. At 29" span it is at risk of getting snagged in the hanger!

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Phil Cooke15/10/2017 07:49:45
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1874 forum posts
1225 photos

Great progress Chris, nice to see you cutting and skinning your own panels - impressive! thumbs up

Chris Barlow22/10/2017 22:33:16
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1665 forum posts
1147 photos

Thanks Phil but really I'm just making it up as I go along and "borrowing" ideas from youtube! blush Nice to see the A-10 back on the bench. yes

A bit more progress this week. Tail plane and fin are now built with one eye on the idea of making them detachable. After some thought and a very late night sketch that I couldn't for the life of me decipher the next evening, I have come up with a solution.

Same method as fixing a wing, I fitted a sub former to the front of the tailplane seat and doweled the tailplane into it.

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Two M4 bolts secure the rear of the tailplane into captive nuts. These will be replaced with nylon bolts countersunk flush.

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The fin is bolted to the tailplane into captive nuts fitted to a 1/2" balsa addition to it's base. For additional support the fin is housed into the tailplane.

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Hopefully in the event of an inverted or snagged landing the nylon bolts will just snap leaving the tail plane or fin intact?

All the above now needs refining and tidying up. In addition the wing tubes have been aligned and fitted and a servo tray installed just behind the cockpit.

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These will be connected to the rudder/elevator via 4mm carbon push rods running in 6mm carbon sleeves through a couple of formers due to their length. For now they are just mocked up to get the route right.

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With the servo tray mounted far forward the balance is now only 3" behind the proposed CoG without the wings! I expect I am going to need some ballast in the form of cockpit detail and a big battery to balance it out!

john stones 122/10/2017 22:55:08
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8856 forum posts
1379 photos

Looking good Chris, soon be ready for a bench fly. smiley

Martian23/10/2017 19:02:21
1612 forum posts
773 photos

Still following 👏

McG 696924/10/2017 08:03:22
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1674 forum posts
730 photos

... still following as well, Chris. yes

Cheers

Chris

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