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Phil's F-86 Sabre build thread

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dirk tinck20/01/2020 23:32:07
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628 forum posts
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Hi Phil,

Are you running the aileron pushrods trough slots in the fuse former ?

Phil Cooke21/01/2020 07:02:18
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No not through slots, that would make fitting the wing too tricky! I'll simply cut away any clashing formers to the required depth once the fus is built - I cant see my fuselage plan (as its on the other side of my building board!) but from memory its only F5 that is concern!?

Phil Cooke21/01/2020 17:35:24
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Both wing skins attached and trimmed - impressed with how 'stiff' it feels - all trimmed up now and ready for the T/E, L/E and tips to be added.

top skins 3.jpg

On the underside I could dress the slots for the drop tank pylons upto the ply features which lie hidden within.

top skins 4.jpg

McG 696921/01/2020 17:48:58
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Very neat, Phil.

Superb progress again.

Cheers

Chris

Phil Cooke21/01/2020 22:52:14
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2588 forum posts
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Good to get the jig off the board so I can read the plan again and recap what needs to be added where still on the wing... Leading Edges added in a short session tonight, cut from 10mm medium balsa sheet with the right taper.

top skins 5.jpg

One odd thing with the wing - a function of the section profile and the sweep I think(?) is that sat flat on the bench (not on the jig) it sits back down on it's T/E and makes it appear that its built with no dihedral or washout - has anyone else noticed this?

Of course when you check the L/E in this position it is raised - lower that with some weight at the front into an approximately correct incidence and the wing tips both rise to better visualise the correct dihedral - all set of course by the jig!! Spooked me for a second as I thought I'd built the wing flat! (and I'd never live that one down, would I Matt!?)

Edited By Phil Cooke on 21/01/2020 22:53:29

Peter Garsden22/01/2020 10:47:45
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1728 forum posts
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Your post reminds me why I always get myself an extra copy of the plan so you can read what to do next! !!

Steve Houghton23/01/2020 22:22:21
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579 forum posts
429 photos

Smart work, Phil. Now that all you experts have ironed out the problems with the wing build, I may be tempted to start mine soon - soon be June!

dirk tinck24/01/2020 00:05:03
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The ''flatness'' of the wing in the back got me wondering too Phil !

Funny what dihedral and a wing-section can do to our minds ! Wait till you offer the wing to the fuse !!It loos like the dihedral in the front is negative and changes towards the backsmile o.

Phil Cooke24/01/2020 15:06:20
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hehe glad it's not just me it fooled then Dirk - we must have similar minds! thumbs up

Gordon S24/01/2020 20:25:05
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Can’t believe you heathens cut up my nice plans!!!!!!!! Took Martin & I hours to HAND DRAW each one!!!!
😂😂😂�😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂😂

McG 696924/01/2020 21:04:47
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... allow me one remark & hopefully sound advice please, Gordon...

... next time bring your drawings to a local copy shop instead of having to "HAND DRAW each one !!!!". wink angel

Cheers

Chris

Phil Cooke25/01/2020 22:45:42
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The aileron Torque Rods and wing T/E were fitted in this afternoons session...

With the sub T/E marked up with an accurate centreline, holes were drilled for the 4 plastic torque rod bearers and a length of T/E section was cut to size (sized for scale ailerons) and recessed out to clear the torque rod.

torque rod 1.jpg

The 4 bearers were secured into the wing with a little epoxy in each semi-recessed hole. I then carefully applied some vaseline to the torque rod to ensure I didn't stick it all up when glueing the T/E on. This was done one at a time with the wing flat on the board. I am conscious I have NOT considered any washout yet on this inboard fixed section (ie - I've not pre-twisted the T/E or alike) - the T/E is just glued to the wing flat on the bench.

torque rod 2.jpg

All secure and awaiting the aileron!

torque rod 3.jpg

torque rod 4.jpg

Both sides attached - resulting in two 'free to move' torque rods - bonus! This is always one of my least favourite tasks in any wing build with torque rods!

torque rod 5.jpg

Phil Cooke25/01/2020 22:58:46
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2588 forum posts
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With the T/E's added I could now apply a small glass fibre bandage as a wing joiner. This isn't shown on the plan - the design isn't deemed to need a wing joiner with there being a dowel and wing retention bolt in each panel, and this has been well proven on the prototype - but I'm adding this just for piece of mind. The good news is it will all be hidden under the belly pan, so no unsightly bandage will be on show!

I cut a 2" wide strip of standard wing bandage cloth, and applied it with PVA, not glass, as we've done before on many other small scale PSS models. The underside gets a full length strip, front to back - PVA can be 'stippled' into the weave with a small brush and a wet finger.

bandage 2.jpg

The top surfaces are too cluttered for a continuous strip, I almost didn't bother adding any on the top side but couldn't help myself in the end - 2 small patches were added fore and aft of the servo bay. I'll sleep a little better now knowing my wing is +9G rated - even if the pilot isnt!

bandage 1.jpg

Edited By Phil Cooke on 25/01/2020 23:02:50

dirk tinck25/01/2020 23:25:32
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628 forum posts
861 photos

Clean and accurate building Phil , i'm jealous.

Phil Cooke26/01/2020 12:30:26
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A little bit of work on the wingtips. Over previous Mass Builds we've developed a 'house style' with tip laminates of balsa/1/16" ply/balsa which provide a lovely robust finish to the wingtip where it gets nice and thin at the T/E. Although it's not shown on the plan I thought I'd go this route again...

wingtips 1.jpg

Taking the shape from the plan I've cut sandwich elements from 1/4" balsa, 1/16" ply and 1/2" balsa. These were all glued up with a little PVA (ensuring you make a L and R handed pair!) which were then pressed for a few hours under some lead.

wingtips 2.jpg

Whilst that was drying I made up the ailerons - slotting and drilling them for the torque rod. Before these are rounded and hinged you can use them taped to the wing to help align the wing tip, ensuring the ply in the tip is angled so it bisects the most forward part of the L/E and the most rearward part of the aileron.

wingtips 3.jpg

I've still not applied any additional wash out, twist or warp into the aileron - I'm not convinced it is needed as I had initially expected... the wing is built with the washout in (formed by the jig) so I think the aileron can just be aligned this way to regulate the angle of the tip?? Do other builders agree?? Or have you twisted or sanded your ailerons with some additional washout?? Jon H? Dirk?? Harry??? I think your wings are all at a similar stage? What do we all think?

Martin Gay26/01/2020 15:15:44
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396 forum posts
255 photos

Hi Phil,

Place the wing back onto the building jig. It should then be obvious if you need to sand any washout into the ailerons.

Martin.

dirk tinck26/01/2020 20:21:27
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628 forum posts
861 photos

It's the only part of the wing that isn't finished yet Phil but even at Half lenght aileron ,i think there is some warp needed.

Phil Cooke26/01/2020 23:03:26
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2588 forum posts
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Following Martin's advice - I placed my wing back into the jig and aligned a short section of aileron stock up square to the sub-TE to check the angle - for me it looked good, not drooped, not raised. I'm using a fully symetrical T/E stock - not flat bottomed, and I think this is helping - although it got me thinking - maybe if it looks right at the tip then perhaps the section further inboard is too elevated? I still wasnt sure...

Gordon and Martin got in touch on email and they explained that on both prototype wings no twist or warp was required on the T/E stock to align them inner and outer. I think we agreed that with the wing being built in the jig, as opposed to being built flat onto a board and then subsequently elevated at the rear with a wash-out wedge whilst you fit the top skin, that the sub-TE must 'roll' or twist a little along its own length as it sits down square onto the lower skin - which is preformed with the washout.

This is my only explanation as to why it looks like you can just push the aileron stock upto the wing sub TE and it looks good at both root and tip with no wash out warp applied! Anyway, I went with it - and set about sticking the tips on...

Phil Cooke26/01/2020 23:07:39
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2588 forum posts
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So with a little epoxy the tip lamiates were glued square onto the end ribs, ensuring the 1/16" ply aligned front and back with the extreme L/E and T/E as shown.

wingtips 5.jpg

wingtips 4.jpg

Just needs a good sand now and the wing is about complete bar the L/E ply face, dowels and wing bolt load spreader.

wingtips 6.jpg

McG 696927/01/2020 08:02:26
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3243 forum posts
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Great progression, Phil.

And thanks for the 'scouting' job. It relieves me a lot to see that we won't need extra ammonia or warping of the triangular stock.

An advice, please > regarding the wing tips as I don't have 'thick' balsa, can I use some Blue Foam with the ply sandwich method as well?

Cheers and thanks

Chris

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