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Phil's F-86 Sabre build thread

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Peter Garsden04/01/2020 16:44:38
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1678 forum posts
1259 photos

Good idea to make 2 at once Phil which is what I did and it is not a problem with the jig, which lines everything up perfectly. Presume you have added 1.5mm to the R1 jig though? Accurate neat building as usual!

Torque rods are definitely more slop free than mounting in the wing and the way to go with just ailerons. I have done flaps and decided not to attempt the fuselage side spoilers - way too much of a fiddle and won't be needed with flaps. Flaps not really needed on a PSS model anyway as they won't be going fast enough.

Phil Cooke04/01/2020 20:04:28
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2390 forum posts
1640 photos

Well I'm committed now with a one peice wing so early in the build...I'll manage but I'm still convinced handling and shaping the panels would have been easier done as singles...using the jig to finally bring them together.

I was a little hasty in my 'next steps' commentary last night as I'd forgotten I needed to prepare the drop tank mounting slots before adding the top spar and webbing... so this has been this afternoons work following the leading examples set by John Hey and Harry Twist.

Deviating slightly, I'm intending to use a pair of snakes with M2 metal end fittings to enable the pylon drop, but again like John and Harry, working from a single, centrally mounted servo.

The drop tank pylons sit between Ribs 8 and 9 so the first job was to make a set of semi-rib mounts - cut from a sturdy piece of 1/4" balsa and sized just a tad smaller than R8.

pylon mount 1.jpg

The inner faces of the slot are to be lined with smooth 1/16" marine ply, 1/8" spacers ensure the pylon mount is a well toleranced, robust fit. Here's a kit of parts prior to final assembly...

pylon mount 2.jpg

...and the fully assembled unit showing the ply lined 'box' - sized at 1" x 1/8".

pylon mount 3.jpg

Here's the assembly dry fitted into the wing between Ribs 8 and 9. I will have to arrange the snake, make up and drill the holes at the required angle and position prior to fitting these into the wings. I'm intending to cut slots in the inboard ribs allowing a straight snake section to 'drop in' without any pre-load, I will then re-cap the rib sections I've cut away and that should be that!?

pylon mount 4.jpg

dirk tinck05/01/2020 00:00:34
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458 forum posts
723 photos

This must be the cleanest workbench of the pack !Great work Phil !!

Over here we would name you Mr. Proper! (Mr. clean)smiley

Phil Cooke05/01/2020 18:33:35
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2390 forum posts
1640 photos

You can't make a model without a bit of mess - but I do try to clean up a little for my photos Dirk smile d

Trying to put off the delicate job of drilling the oblique holes into the pylon mounts I trimmed all the rib L/E to the correct angle and sanded them back to the correct line with the help of a little sanding tool I made - cut from a length of 1/2" triangular stock. This was sized to 'bridge' 3 ribs ensuring that they all stayed true and proved very useful! Once all cut back I made up the sub L/E from balsa sheet.

sanding le 1.jpg

The reason I wasn't looking forward to the drilling task was that I don't own a pillar drill, this was always going to be down to a steady hand and eye... those with a H&S background please look away!

I mounted my Dremel onto the bench with a sturdy grip, checking the cutting tool was all square to my bench. I then elevated the work peice to the correct height by selecting some wood stock of the required thickness... With datums drawn and a steady hand we proceeded with the cut, keeping the workpiece flat on the bench and pulling it towards me onto the Dremel along the datums - with a keen eye from above!

drilling 1.jpg

drilling 2.jpg

The hole was cleaned up and the snake outer proved a good snug fit through the balsa/ply/balsa laminate.

drilling 3.jpg

I still had all my eyes and fingers in place - so I proceeded to cut the same hole in the other side!

Edited By Phil Cooke on 05/01/2020 18:36:20

Martin Gay05/01/2020 19:31:48
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327 forum posts
245 photos

That's one of the things I like about this hobby:

"Improvise, adapt and overcome" thumbs up

Phil Cooke05/01/2020 19:52:18
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2390 forum posts
1640 photos

With the mounting blocks drilled for the snake outer the inboard wing ribs could be relieved to accept the snake running to the centreline servo. Again I made a little sanding tool which helped shape the bottom of each slot, the tiny little scalpel saw was also a life saver in cutting down into the ribs without inducing too much physical load into the wing assembly (my ribs still don't have top spar of webbing!)
slots 1.jpg

Ribs 2 to 9 were slotted along the required path - the depth of slot was premarked to keep it all straight and smooth...(there are 2 marks I know, my first was in error and too low!) I kept the material removed from each rib which will help me recap them once its all glued up.

slots 2.jpg

The first snake outer is pressed fully into place but cant be glued yet, I will need to make up the internal pushrod before it is finished as the metal end fittings will mean access will be impossible once fitted.

slots 3.jpg

Finally the snake outer is cut away inside the ply box, allowing the pylon to drop away once the inner pushrod is clear. One downside to my method is that I couldn't simultaneously drill the pylon with the smaller reqired hole whilst machining the mounts (like John Hey did in his blog) - so another operation for me with the drill later on...

slots 4.jpg

Phil Cooke11/01/2020 22:00:50
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2390 forum posts
1640 photos

Another week flies by...and a hectic one with work meaning no workshop time until today too! embarrassed

I've completed the pushrod and servo layout for the droptanks today which now means I can crack on with the wing construction. I mounted a trusty Hitec HS-85MG as close to the centreline as I could without cutting through the Rib 1 pairing, positioned by eye onto a pair of hardwood bearers where I thought the snake runs would exit. Any final adjustments can be made with a bit of pushrod bending later on.

pushrods 1.jpg

I then cut a couple of lengths of snake inner and made up the M2 metal ends. At the drop tank end I wound in on the thread for a couple of inches making the 'working' length of the inner nice and stiff where it runs in and out of the ply pylon mount. I 'domed' the end of the pushrod with a file and then further radiused the snake to ensure there could be no binding faces should there be any slight mis-alignment.

pushrods 2.jpg

At the other end I simply cut to length and exited the pushrods vertically for final adjustment later on. I need to choose a bigger servo arm and perhaps fabricate that a little to make the ideal angles with equal throws each side of the servo axis. The pushrod runs are nice and smooth and need just 1/2" of movement to take the tanks from 'locked' to the 'drop' position.

pushrods 3.jpg

Phil Cooke11/01/2020 22:02:40
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2390 forum posts
1640 photos

'Locked' - you can see the inner fully spanning the gap in the snake housing each side.

pushrods 5.jpg

And 'Drop'... smile d

pushrods 4.jpg

Phil Cooke12/01/2020 13:51:20
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2390 forum posts
1640 photos

Final configuration at the servo end. I found that Futaba servo arms fit the HiTec HS-85 spline very well so I was able to create the geometry I needed from a larger Futaba fitting - the ball links help take out a little rotational arcing evident with the stroke needed at this radius. It all seems to work very smoothly having now made a few minor adjustments on travel, pushrod length and angle. Time to glue it all up!

The first photo shows the tip tanks 'locked'...

pushrods 6.jpg

...and this is the resultant position when 'released' - there is no binding despite it looking like a clash in the photo!
pushrods 7.jpg

McG 696912/01/2020 19:39:52
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2921 forum posts
1107 photos

Great technical achievement, Phil.

I will only presume that it means you can start the aileron torque rods very soon now. yes

Not that I'm waiting for them, obviously... devil

Cheers

Chris

Phil Cooke12/01/2020 19:59:29
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2390 forum posts
1640 photos

Hi Chris,

I wont be fitting the actual torque rods until after the top sheeting is added and the wing is removed from the jig, although the centrally mounted servos need to be added before that - soon!

Phil Cooke12/01/2020 23:02:30
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2390 forum posts
1640 photos

The snakes have been permanently fixed along their route through the ribs and the rib slots have been refilled and sanded back to profile.

pushrods 8.jpg

Chris had got me thinking a little about the torque rod installation so I positioned the bearers and set about making up some little balsa block doublers for the relevant sections - 4 off per side.

pushrods 9.jpg

Similar soft blocks were cut for the robart knuckle hinges I'm planning to use for the ailerons which protrude a good inch into the wing T/E. These still need to be sanded back to the rib profile in the shot below.

pushrods 10.jpg

Just the top spar and the webbing to add to the wings now before we can close it all up with the top sheeting...

Edited By Phil Cooke on 12/01/2020 23:02:56

Phil Cooke18/01/2020 10:25:03
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2390 forum posts
1640 photos

Another little job I needed to do before the top skins can be considered - I'm adding a 2mm carbon pin to the rear of the pylon just to aid 'anti-rotation' of the drop tank in flight - this required a little ply slot mounting into the lower skin to act as a location bearer. The slot enables the pylon to rotate and drop away better than a simple hole would do.

Cut from 1/16th ply.

pylon anti rotate.jpg

and to be mounted roughly here on the lower skins...

pylon anti rotate 2.jpg

Phil Cooke18/01/2020 19:42:20
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2390 forum posts
1640 photos

A bit more done on the wing assembly this afternoon which I think is now ready for a final sand prior to the top sheeting going on - finally! - it seems to have taken ages!!

Top spars are all fitted and with them in position I added a couple of hardwood bearers for the central aileron servos.

servos 1.jpg

A couple of Hitec HS-65MG+ will do the job, as proven on the 2018 MB Hurricane.

servos 2.jpg

I've then added all the balsa shear webbing between the top and bottom spars, electing to add them just on the rear face of the spars and going up to 1/8" balsa (the plan shows 1/16" front and back)

servos 3.jpg

Assuming I haven't glued the wing to the jig with over zelous use of thin cyano through the lower skin (has anyone encountered any problems?) the wing will be removed from the jig now to enable the L/E, T/E and any other highspots to be sanded to the rib profile.

McG 696918/01/2020 20:10:14
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2921 forum posts
1107 photos

Great and extremely neat progress, Phil.

I assume your servo supports have to be in one piece allowing an extra bracing at the wing junction.

I'm building my wings as two separate items so far, can I split the bearers or is it advised to keep them united?

Cheers

Chris

Phil Cooke18/01/2020 20:41:02
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2390 forum posts
1640 photos

Splitting them will be no issue. I've joined my wings at R1 on the jig, so running them through one peice here made sense to me, but in no means do they act as wing joiners, just servo bearers. I will be using a 2" glass fibre bandage around the wing CL once the top skins and L/E and T/E are fixed - akin to a simple foam wing.

McG 696919/01/2020 08:22:09
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2921 forum posts
1107 photos

Thanks for your answer and the bandage idea, Phil. yes

Cheers

Chris

Chris Barlow19/01/2020 14:38:44
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1897 forum posts
1303 photos

Very neat Phil. yes

How do you get your photos so clean and dust free? Do you build and photograph in different areas or just clean up and vacuum for each photo?

Or is it OCD? wink

dirk tinck19/01/2020 22:24:31
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458 forum posts
723 photos

Hi Phil ,

I had a couple of spots where the cyano got to the wing jig but nothing serious tough...

unbelieveble clean build chief !

Phil Cooke20/01/2020 22:54:40
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2390 forum posts
1640 photos

I don't have a separate room for photos, but I do have a little spruce up before photos are taken on the bench, and I tend to do all but the smallest of sanding jobs outside or at the garage door as much as poss, not on the bench.

Top skins added this evening after a final R/C check. Once trimmed and aligned at the root around the servo bays, the skins were pinned out along the top spar, the T/E was weighted down flat into the jig and the L/E was rolled over and battoned down along the sub L/E.

top skins 1.jpg

Skins trimmed for the servo bays and the drop tank pushrod articulation.

top skins 2.jpg

Edited By Phil Cooke on 20/01/2020 23:03:02

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