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Boeing B52 PSS Glider

BUFF is one of my winter projects

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Paul Marsh01/01/2012 19:26:02
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The B-52 I built was done with brown paper and PVA. Was balsa fuselage and built-up wings with balsa sheeting. It was cheaper than most other coverings, due to the budget limitation of the ATC model budget for B-52. It won more than once at Wing HQ Stafford Aeromodelling competition those years ago.
Tim Mackey04/01/2012 16:37:09
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As we cancelled the Orme session ( good call incidentally its pretty horrid here ) after my chores, I got stuck into veneering. First off the 1.5mm balsa are trued up, and butt joined to make a panel - I used PVA as it sands pretty well.
A light sanding all over results in a nice clean smooth panel.
Next I try to maximise sheet usage by positioning of the cores to suit.
The panel is marked for cutting allowing a small overlap all around.
 
I managed to cover both halves, on both sides with one panel.
 
Any holes in the foam cores ( and there were quite a few after sanding ) are filled with "nutty putty" and then after this has set, its sliced off flush and then sanded.

Get everything prepared - I cover my workbench with a cut open large bin liner. I use copydex latex glue to apply the veneer, and brush on a thin coat to all surfaces using a jenny brush - it washes out much easier than a bristle brush.

I find the sheets tend to warp after the glue is applied, as can be seen above - so to stop it curling, I weigh it down with plastic bottles which wont stick to the surface. Then the cores are placed into their saddles and given the same glue treatment. Here they are seen ready to accept the second side sheeting. Always allow plenty of time for the glue to dry before applying the sheets - I usually wait around 30 minutes.

I start by aligning the T/E and pressing firmly and positively into place - remember there's an overlap so dont worry too much if its not lined up perfectly. Then I work my hand smoothly and evenly over the surface pressing the sheet down as I work toward the L/E

A quick trim with a scalpel, then the permagrit, and a final light rub over with fine sandpaper has them starting to look OK. Heres a quick mock up to test the spar alignment etc.
 
Next job is to cut out the control surfaces, and then let in some balsa pieces to the leading and trailing edges where the hinges will go, then fit balsa edging to all edges. Then its sanding down to shape the profiles all round. Finally, I will cut out the servo well for the rudder servo along with cable routing, and make up a servo mounting system.
 
 

Edited By Tim Mackey on 04/01/2012 16:38:24

Tim Mackey07/01/2012 15:32:08
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Took me almost 3 days to get the tailplanes surfaced, and the fin to this, almost completed stage. I cut out a servo hole in the fin, and although not clear from the picture, it was then "lined with epoxy and microballons. The servo was wrapped in clingfilm and pressed home, so forming a moulded "socket" for a nice snug fit. A liteply mounting plate was made up, and the servo glued and screwed to that. Ply plates are let into and glued in the corners of the servo well, for fixing screws. A hole was made down to the root for the cable, and sleeved with heatshrink...to facilitate removal of the servo at a later date if ever required.I plan on similar arrangements for all servos, as I just dont like the idea of not being able to easily access/remove servos in future.
Ive used Kavan flat plate pin hinges, which will be PU glued into place at final assembly stage.
A short C/F pushrod and associated 3mm fitting were made for control and all seems to work nicely.
The leading and trailing edges of both the fin and the rudder were glassed with lightweight glass cloth and Poly-C, and the main panel surfaces used tissue and Poly-C to keep things light. All rubbed down its feeling nice and smooth, but several more filler coats are yet to be applied before priming and painting




Edited By Tim Mackey on 07/01/2012 15:34:17

Phil Cooke09/01/2012 21:30:52
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Looking really good Tim!
How long does the Poly-C take to dry between filler coats?
And if you have tissued the main section of the fin panel, but glassed the L/E and T/E regions - were you left with a step and if so how have you dealt with that?? Or is the glass a similar thickness to the tissue?
 
Tim Mackey09/01/2012 22:15:26
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Thanks Phil - in a warmish room, the Poly-C dries in around 15 minutes - enough to add the next coat at least. It gets progressively harder over the weeks.
There is a small step between the two, but after a few more coats of "C" it will sand down to be almost invisible - besides have you seen the state of the full size ones
Tim Mackey12/01/2012 10:55:21
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Tailplanes and fins are all now finished apart from final few coats of Poly-C ( I'm awaiting delivery of more stock ). Im almost immobilized with back trouble today, so wont be doing much. Last night I started work on the fuselage sheeting and though peeps may be interested in the method. Unlike the tailplanes, the curvature of the fuselage halves is too severe to simply wrap the balsa around, so it needs to be made more flexible. After making up the panel from the planks as per the tailplane, it is then cut to roughly the right shape and size, and placed in a bath of water and left overnight to thoroughly soak.
Best to use waterproof PVA here. The sheet is then placed in the saddle, and the foam fuselage section is gently pressed into the "mould" upon which the balsa then forms into shape. This is then allowed to thoroughly dry in warmish place.
 
The wetted sheet is placed over the open saddle.

....and then the piece is placed into the saddle, forming the balsa veneer.




Once completely dried, the balsa will retain the desired shape and can then be glued into place a la fin method shown earlier.
 
Wingman12/01/2012 11:26:09
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How decadent is that?? Model making (nearly said "modelling" which flashed a horrible picture of Timbo through my head) in your dressing gown
Olly P12/01/2012 11:39:08
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Wingman - I often do the same - that little extra bit of gluing just before bed allows another bit of glue to go off overnight! Means I can sometimes get 2 waves in in the eveing if I work fast enough to do some before SWMBO gets home.
 
Olly
 
PS, mine isn't nice and strippy though...
Myron Beaumont12/01/2012 12:18:41
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It's been shown apparently that vertical stripes do not make you look thinner contrary to popular belief . It's a smoking jacket isn't it ?
There's posh isn it

Edited By Myron Beaumont on 12/01/2012 12:30:01

Phil May12/01/2012 12:27:16
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Looking good Tim, model that is ...........
 
Will it be ready if I venture up to your neck of the woods in the spring?
 
 
Phil
Matt Jones12/01/2012 12:44:38
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Looking good Tim, sorry I'd missed this thread Ready for the April meet?????
 
It looks like there may be a third '52 on the way,, not for a while yet though.
 
Tim Mackey12/01/2012 13:14:57
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Posted by Wingman on 12/01/2012 11:26:09:
How decadent is that?? Model making (nearly said "modelling" which flashed a horrible picture of Timbo through my head) in your dressing gown

Smoking jacket old boy....

Tim Mackey12/01/2012 13:16:22
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Posted by Olly P on 12/01/2012 11:39:08:
Wingman - I often do the same - that little extra bit of gluing just before bed allows another bit of glue to go off overnight! Means I can sometimes get 2 waves in in the eveing if I work fast enough to do some before SWMBO gets home.
 
Olly
 
PS, mine isn't nice and strippy though...
I do hope you meant STRIPEY Olly
You really wouldn't want to see me stripping mate - honestly.
Tim Mackey12/01/2012 13:16:59
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Posted by Myron Beaumont on 12/01/2012 12:18:41:
It's been shown apparently that vertical stripes do not make you look thinner contrary to popular belief . It's a smoking jacket isn't it ?
There's posh isn it

Edited By Myron Beaumont on 12/01/2012 12:30:01

 
Well done Myron old boy
Tim Mackey12/01/2012 13:18:05
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Posted by Big Phil on 12/01/2012 12:27:16:
Looking good Tim, model that is ...........
 
Will it be ready if I venture up to your neck of the woods in the spring?
 
 
Phil

I am aiming to heave her ready for the first PSSA meet on the Great Orme April 21st.

Tim Mackey12/01/2012 13:20:01
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I have now removed the veneer from the saddles, and strapped around with masking tape in order to let the warmth get at the sheeting and dry it out.
I find it takes at least 24 hours to properly dry.
Tim Mackey12/01/2012 13:29:03
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Posted by Matt Jones on 12/01/2012 12:44:38:
Looking good Tim, sorry I'd missed this thread Ready for the April meet?????
 
It looks like there may be a third '52 on the way,, not for a while yet though.
 
Wow, another one - this will actually make 3 new ones then ( I have cut two as a mate is doing one also ) plus, the two new ones that have been done by Scott and Chris - who have pledged to try and make one of the meets this year.
If they all make it, with Si's original as well that means we have a squadron of six!
Just imagine the sight ( and sound ) as they all appear from around the corner of the Orme in low level formation past the slope.....
 
Incidentally, anyone know where we can get the wing whistles from? - the ones Simon uses are very effective.
Matt Jones12/01/2012 13:41:18
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I think Phil might have sourced them originally, not sure.
 
Interesting to see how you veneer, I've always done mine dry without preforming. I coat both surfaces, allow to dry and then just press together.
Tim Mackey12/01/2012 14:51:37
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I'll ask Phil. I was told by another recent B52 builder that when he tried it dry, the panels kept splitting 'cos of the acute angle at the bottom of the fus section .....this method seems to work fine, so I'll "stick" at it.
UPDATE: just this second recived notice from Barry at foamwings that my wings are shipping tomorrow 

Edited By Tim Mackey on 12/01/2012 14:53:09

Olly P12/01/2012 15:00:27
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Hmmm...looking good Tim.
 
How much is it to get foam wings to make a set of wings - presume that depends on the size of them.....

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