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Martyn's F-86 Sabre Build Blog


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As we have started bagsying (I haven't used that word since I was kid - far older than the spell checker reference dictionary) colour schemes, I have decided to go with this very loud scheme. It will be a real test of my painting capabilities.

Bring out the dancing girls laugh

I'll get my kit when I get back from my holidays hopefully. At the moment desperately trying to get some of the WIP models finished

Martyn

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  • 4 weeks later...
  • 1 month later...

Its 1st of November and its traditional to make a start.

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Its a Battery Box. laugh

Just needed a little bit of fettling of the end cap to fit nicely.

However, the round holes appear to be at the wrong end..

I don't think that is important or cant be easily remedied if it is a problem..

In the meantime, I am still reviewing the plan.

More to come

Martyn

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Made a start on the fus this morning. The fus may appears to be built around the central 3 formers so started there. A bit of very light fettling to get the 4 ply parts to fit and laid up over the plan. Used squares to ensure that the vertical parts were indeed vertical

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With that assembly dried, I built the same assembly for the other side, using the left hand side as a jig to make sure the parts will align when the two halves are matched up

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More to come. Hopefully get the left side framed up this weekend

Martyn

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A bit more progress on Saturday.

Getting the LHS pinned down and framed out. All very straight forward so far

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The fus was a simple extension of the centre 'box' and went together quite easily

Some 1/8" sheet hard balsa was stripped for the rear outer frame and pinned down.

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The formers added and all push gently together so I can remove the excess glue..

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I actually missed fitting the ply tail mount and had to redo that.

All the ply to ply joints need a little manipulation to get a good tight fit but its not onerous. Just take your time and it will go together quite well. One of the joints was so tight that I couldn't separate it after a dry fit so simply left it and wicked some cyano in.

Nothing done yesterday as it was the UKCAA AGM them minute writing.

3/16 square longerons cut this morning then scarf joints - they will be fitted this evening.

More to come

Martyn

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Moving on and apologies that this is a little late.

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while waiting for the glue to dry I assembled the wing building jig. This was a real treat although I plan to assemble the wing slightly. I didn't glue my jig, just relied on the good fit between the horizontal and vertical parts. The idea is that I can strip it down and store it until I break the wing after the maiden.

dsc_1292.jpg It really does go together well

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Back on the fus. The remaining stringers were added. I used balsa but TBH, I wish I had used Spruce.

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F3 and F5 were a bit tricky. They need adding at the same time that you glue the stringers in but the natural curve of the stringer will try and lift them so the stringer needs pushing down with weights to hold it in place while the glue dries. Not a big problem

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Scarf joint for the stringers. The are longer than 36" so a joint is required. I stagger my joints so that are not all in one place.

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With all the stringers in place and while the 1/2 was still pinned down. I added the first of the two planks. I prefer to make my planks as wide as possible - especially on the relatively flat area. These are 20mm wide. I soak one side (the outside with a spray bottle) and pre-form the curves by gently bending between my fingers. Mark and glue the frame then clamp then into place and leave them to dry. I use clamps to hold them down as well as pull them together. Wide strips = less glue and less filler if your joints aren't brilliant. I tend to sand a taper (as the front and rear on the plank will normally be around a smaller radius) and also slight bevel to get a good joint. One thing to watch if you have never planked before is that it is OK to bend the plank down the length, however try and avoid bending it laterally as well as they will put stresses on the join and also induce a fuselage twisting action.

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Close up..

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Where possible I try and terminate the joints on a former so when the next plank goes on it will have something to glue to. I also stagger my joints as much as possible.

 

Edited By Martyn K on 11/11/2019 13:35:26

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With those first two planks in, the half should be stiff enough and torsionally resistant. I now deviate from the instructions and assemble the 2nd half directly over the first half.. Why? So I cam take advantage of the flat bottom. Don't forget the wing plate...dsc_1302.jpg

like this. It need a bit of fettling to get it to fit. 5 minutes with a sanding block. Nothing too bad..

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The wing 'box'had already been assembled so it was a simple job of getting it to fit..

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Wing plate in place

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The second half assembled. No problems

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The matching two plans now added to the right hand side

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While waiting for the glue to dry, I made a start on the wing. Bottom spar from hardish balsa. The plan says they are 1/4 x 1/8 balsa, they are actually 3/16 x 1/4 balsa

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Each rib then had the spar slots recut to accommodate the sweepback. I used a 6mm spar slotter from permagrit

The observant will notice a second deviation from the plan. I haven't added the lower sheeting. Two reasons, 1. I want to fit servos etc before the lower sheet is fitted and 2. I can use the frame to align the ribs while the glue dries - like this..

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Lots of clamps and no pins

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False LE and TE added - this required the ends of each rib to have a vertical taper cut. I used a razor blade

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And while the glue was drying on the wing I carried on with the planking taking advantage of the fairly flat area to add wide plans. I don't have sufficient space to use as many clams as I would like to the pins are out.

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Plank 3 in place

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The two lower areas each side of the wing mounting area ae very flat and can be easily sheeted over. Very very wide planks

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The other wing half in progress while waiting for the glue on the fus to dry..

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The plan specifies a 3/16 ply LE plate. I only had 1/4 ply handy so trimmed of 1/16" off the front edge of R1 to R3

The upper spar added. I have used spruce for the first 60% of the wing spliced to balsa at the tips.

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And there is the joint.

More to come,

Martyn

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  • 3 weeks later...

A bit of a delay - apologies..

There has been some progress though. I have a new laptop that is adding to my typing turmoil as it has a different keyboard layout

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Added a short central brace (top and bottom from 6mm balsa. Links the two halves together quite nicely

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Started work on the elevator horn. Mine is made from 1.5mm glass fibre sheet to the same layout as the plan. A brass bearing tube with supporting washer epoxied in place as a pivot. This site inside two hardwood blocks with brass tube bearing. Shouldn't be any wear problems.

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Meanwhile the planking goes on

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and on..

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The wing seating area now cutaway. I wish that I had half cut that former before I glued it into place..

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The upper side of the wings sheeted and glued into a test fit fives me a nice indication of size.

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I will fill the wing roots in when the wing gets bolted into place

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A test fit of the horn, its offset because I am using an internal rudder torque rod

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R/E servos fitted. Lower than shown on the plan because I am using pushrods rather than snakes

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Fin sanded to shape and fitted. The hinge line for the rudder has been moved forward about 3mm to clear the elevator hinge

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Measured the angle directly off the plan and checked it was vertical by using Mk1 eyeball against the wing. It needed a little packing to sit against the ply side plates

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Added a little more sheeting around the fin. There is not much of a curve here and one piece of 3mm balsa fitted nicely

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and more planking...

....continued

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The rudder torque rod looks like this. The bearing tube is square, the horn is angled and the lower bearing block is essential

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Elevator horn is temporarily removed (yep - got this bit in the wrong order) and the torque rod bearing glued into place

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Through the gap in the fus view. A ball link is essential as the linkage will twist. The lower bearing is glued tyo the lower spine

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Another view with the dowel pushrod fitted

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Upper fus now fully planked

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Fin fairing fitted. Note the blood. It will fly well

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The servos are mounted on a ply tray with 10mm beech blocks for the screws

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Now its getting tricky. Fitted the tailplane fairings. Lots of weird shapes to sand from underneath

dsc_1371.jpgWhile that was drying, more planking zzzzzz

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Started work on the nose. I added an additional 6mm balsa layer before the 3 nose pieces went on and then started sanding to shape. I don't think its a million miles out.

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Yaay. The planking is finished. TBH, I am quite pleased with my planks, very little filler is required

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Working on those tailplane fairings. It needed little bit of infill..

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Started on the exhaust cone. Laminated from 6mm and 12mm balsa

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and after a bit of sanding. The inner was rounded using a dremel drum sander

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The tailplane fairings are faired into the fin using well shaped triangle stock

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Fitted and sanded.

Only a little more progress in the past couple of days as I have had a dose of man flu.

More to come

Martyn

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Thanks Martin

I'll be bending in situ (carefully)... When I eventually fit the tailplane halves, they will be epoxied into place. The rear rod will have bend at the end to keep it located and rigid. A detachable tailplane tailplane would be nice to have but not essential on a model this size.

Martyn

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