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Phil's F-86 Sabre build thread


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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

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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

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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?

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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...

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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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Hi Chris,

I think I've only gotten away with it because of the symetrical Aileron section Im using as opposed to the usual flat bottomed T/E stock. I hope so anyway, otherwise it means my tips are drooping at the back by a few mm.

Blue foam will work to create the shape of the tips of course, but in my opinion it would be a little too soft to act as a wing tip - they take quite a lot of abuse on the slope and in transport. Of course you could put brown paper and PVA over the blue foam before you glass the wing - that would harden it up sufficiently.

Alternatively is to make up the thicker stock with laminate - it's only 1/2" on top so just 2 laminates of 1/4" will do it.

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Nothing really to report following a busy few days at work, I've just not had the mindset to get back in the cold uninviting garage...

Tonight I have turned the building board over and started to at least familiarise myself with the kit of fuselage parts - I'll be following Harry's lead and will be making some sub-assemblies first - with any luck I should be planking by the weekend!

fuselage build 1.jpg

The coloured profile view of course is not my chosen scheme, I will be using that later for scale reference on wing pylons and drop tanks... for now - the wing has been put to one side complete effectively bar some final sanding.

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1st February already! 3 months in...

Thankfully family plans this weekend have enabled me to focus pretty well with a couple of lengthy sessions in the garage today, and some good progress finally made on the fus.

I spent a couple of hours fettling the light ply parts, ensuring each element had a good dry fit whilst removing all burrs and machining witnesses. Once done I set about making up the 3 sub-assemblies for each half of the fuselage - the nose section, the wing box and the tail mount.

fus build 2.jpg

With those glued square I pinned out the straight top spine and the curved lower spine to the plan - I found a couple of the formers were a little short in height so adjusted the lower curve evenly to best suit, then glued everything in square and vertical working from nose to tail.

fus build 1.jpg

Once that was dry I added the balsa stringers, which require a fair bit of twist along their length to sit perpendicular to the local former surface. I found all the pre-cut slots to be bang on for width and depth - lovely!

fus build 3.jpg

fus build 4.jpg

Like others have stated I couldn't cope building one of the sides upside down so I rotated the building board and focused on one side at a time.  A really enjoyable days modelling going from a box of bits to a pair of fuselage sides now ready for some planking!

Edited By Phil Cooke on 01/02/2020 23:25:56

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Hi Phil ,you will soon be having a fuse now !

Just a little advice : I found out the hard way ,that it's best to glass the wing before all the fitting to the fuse begins.

It gets so easy damaged that mine has a few (more than i like)scratches and dents ,even being carefull ...

Keep up the good work !

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Hi Austin - looks like you are making better progress than me!!

Yes the V is std trailing edge or aileron section and the 'fillet' would therefore have to be thin to blend with the back end of that aileron section. The ply plate DOES sit on the bottom of the wing and you then build a belly pan around/over it to blend the wing into the fuselage. Remember the wing will sit lower into the fuselage than it does in your photo, I'm assuming you still have to cut the wing saddle out etc...

take a look at Dirks blog - hes just completed this part of the build and has put up some excellent photos...

Dirks Sabre

and for reference, heres the Gamma build thread from Gordon/Martin

gamma build

Edited By Phil Cooke on 05/02/2020 23:18:09

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Hi Phil, thanks for your prompt reply and the links. I may be ahead of you because I stay in the UK and don't go gadding off to Mexico. I'm sure you will soon pull ahead - I'm 3 steps forward 2 steps back. I thought I would show you my workshop before I lose it. I've just received an Eviction Notice (Kath wants to hold a Coffee Morning).p1050175.jpg

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Ok - enough 'canoe' building for now... 3 sessions today from first thing before football practice with the last pins going in just an hour ago...tomorrow I look forward to taking these halves off the board and prepping them for the big join! I've made up the battery box and the ply wing mount plate in readiness!

planking 3.jpg

planking 4.jpg

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