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Phil's F-86 Sabre build thread

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Andrew Edmead25/03/2020 23:21:53
42 forum posts
29 photos

Hi Phil.

Couple of questions, I noted somewhere that you can build the moving elevator with or without dihedral, Is it just a scale feature?

Also can you give me any tips how to ensure I fit the tail actuator perfectly level?

Thanks for updating your blog, watching with interest.

Andy

dirk tinck25/03/2020 23:41:11
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513 forum posts
786 photos

Hi Phil, the trailing edge corners on your wing look very sharp ! I always have problems keeping them clean !Few of them are roundedembarrassed.Better leave them a bit thicker next time...

Phil Cooke26/03/2020 07:31:50
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2449 forum posts
1703 photos

Hi Andy,

Only Chris' Sabre Dog variant was built without the tailplane dihedral - that is scale for that type (I dont understand the aerodynamics myself?) but certainly if you are building a more regular F-86 then the tailplane dihedral is the only way to go for scale.

As for levelling the tail actuator, if you have glued the 2 fuselage halves together without misalignment then the grooves pre cut in F-15 will ensure the actuator sits level - or as level as it needs to be - the width of those slots will need opening up to suit the brass tube you use as a pivot, but the depth of those slots is pre-cut and determines the angle of the tailplane axle. I can't say mine is accurate to 2 decimal places either, and there's loads more tolerance stack up yet to come with the fitment of the tails onto the bent rods. Only once its all set up with the wing and fin assembled can you really stand back and say its all symetrical, and make the required ajustments then as necessary - bending rods or opening out tailplane slots etc.

Dirk - the 1/32" ply sandwich filler in the tip blocks allows you to sand right down to that thickness (and thinner if you wish) at the T/E and it all remains very stiff and robust. I hate soft perishable T/E corners too!

Edited By Phil Cooke on 26/03/2020 07:34:01

McG 696926/03/2020 09:18:34
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3027 forum posts
1144 photos

Hi Phil,

Hello Andy,

The Dog version of the F-86 has indeed no dihedral for the elevators.

There are a few other 'exceptions' like the F2-J Fury and the F3-J, both being the Navy and Marine Corps versions of the Sabre. They were heavily modified for carrier use like '6-3'-type folding wings, longer nose strut and a different canopy for better visibility, amongst other mods.

fj-2_fury_vmf-312_c1955.jpg

As Phil stated, the more 'regular' types of F-86s do have 10° dihedral for the elevator.

Please don't ask me what the aerodynamic result might be in both cases as I have no clue... blush

Cheers

Chris

dirk tinck26/03/2020 12:18:20
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513 forum posts
786 photos

I was already past the wingtips when i saw the tip regarding the wing-tip ply doubler Phil...I will keep it in mind .

Regarding the tail dihedral :Maybe they use them as tailerons ?With dihedral it becomes in fact a V-tail . So with aileron input you get an amount of rudder also. Just an ideasad

Phil Cooke28/03/2020 16:55:01
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2449 forum posts
1703 photos

The last fuselage planks are added... finally!
last planks 1.jpg

Now to dress the cockpit cavity,,,

Phil Cooke29/03/2020 18:33:18
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2449 forum posts
1703 photos

Started a job today I've not been looking forward to for a while... marking out and cutting back the wing saddle in the fuselage sides...

I used the 'sharpened metal rod' method as described very well in Steve Houghton's build blog. Using the inner ply formers as a guide, this worked well to 'prick out' a curved line just proud of the final required shape. That material was cut out by hand and I used a length of 2" dia plastic pipe with some decent grit paper glued to it to sand out to the required profile. The central overhanging ply former was tackled with the Dremel and a grinding wheel. Still a bit to do fore and aft of the ply saddle formers where the profile runs out, I'll complete that once the wing is married up. I'm conscious too that more material is needed off to allow for the thickness of the wing fillet foundation - (1/32 balsa or ply normally) - so more shaping ahead.

wing seat.jpg

With the top planking complete I could trim back the cockpit area to suit the canopy. The canopy was trimmed to shape and fitted delicately to the fus to enable me to trace the edge onto the planking. That line was then offset by 10mm inboard to form the curved edge of the cockpit lip. i made a little sanding tool to help here.

cockpit cavity 1.jpg

After I finished this and refitted the canopy I felt that 10mm was too much by eye, so I offset again by another 3mm giving a 7mm lip to the canopy, this looked a lot better IMO. I've still to make up the canopy blend at the front, something to complete once I've sanded my planking...

cockpit cavity 2.jpg

I cut my canopy to the line as evident in the Vortex canopy, I think there's a little meat on the canopy still cut at this position - it sits a little high for me, what do others think? Maybe the line is conservative, feels like another 5mm could come off this in height for scale?

cockpit cavity 3.jpg

Martin Gay29/03/2020 21:44:13
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350 forum posts
245 photos

Phil,

The canopy cut line is conservative!

Martin.

dirk tinck29/03/2020 21:56:42
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513 forum posts
786 photos

Mine sits a little lower i think,I couldn't mesure it as she's in glassing modefrownIn the photo you posted earlyer the pilot's head almost touches the canope !Mayby that was a big guy...

Peter Garsden29/03/2020 22:31:01
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1713 forum posts
1297 photos

My canopy line was correct, but mine is splayed out more than it should be due to the shape of my flattened cockpit area. It is all adjustable depending on where you put the raised border to glue the edges to. Great work as always though.

Phil Cooke30/03/2020 13:49:15
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2449 forum posts
1703 photos

In preparation for a bit more detail 'sculpting' at the rear of the fuselage around the jet pipe, I added a small piece of 1/16th ply to give a nice sharp corner - as per Dirks build. I then 'capped' the two tailplane cheeks with 1/16th balsa, maintaining the height and bringing them flush with the two ply F15 formers, which were just proud before on my build. These caps also enabled me to improve the scale looks and blend into the fuselage ahead of the fin, especially with a fillet of lightweight filler to complete the blend.

tailcone 11.jpg

tailcone 12.jpg

Phil Cooke30/03/2020 18:14:35
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2449 forum posts
1703 photos

A little more carving at the tail end - just the exhaust to mill out back to F10 now. It's nice when adding a scale feature actually reduces weight and volume - although the geometry isn't going to be easy to glass well... hmmm - a problem for another day!

beer

tail end 1.jpg

tail end 2.jpg

McG 696930/03/2020 18:20:57
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3027 forum posts
1144 photos

Hi Phil,

I think adding a bit of height to your fillets is truly improving their scale look.

Strangely, I added 3mm as well to mine on the Dog and it looks quite better. cool

I just came back from La Grotte 'fighting' with a start to the cockpit details and it made me think about your canopy 'height'.

I took some measures as it might be of help.

At the end of that ovoïd front screen - where the canopy should open on the full size - I took a piece of paper on top of the canopy and measured 158mm from the left edge to the right one.

You could possibly measure yours to compare, but it looks like yours is a bit to high on your pictures.

Hope it helps you.

Cheers

Chris

Phil Cooke30/03/2020 21:00:28
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2449 forum posts
1703 photos

Thanks Chris, I'll perform a similar measurement - Martin has confirmed that the marked line in the vac-form is conservative to avoid over-trimming with there being no framework, as a guide - so I'll nibble into it incrementally until the height looks about right.

Not easy without the framework as it looks like theres too much glass even when the overall shape is right! I might add some tape framing to aid the trimming.

McG 696930/03/2020 21:23:37
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3027 forum posts
1144 photos

You're mostly welcome, Phil.

You're right, it looks like there is 'too much glass' without a framework.

I'm convinced, reading Dirk's post, that your pilot's head should be quite close to the canopy, just following the side/lateral pic you've posted a while ago.

My pilot's head - albeit not the same as yours but a correct 1:10 scale - stands about 10mm under the canopy.

Please give us a return on your measurements as it could help a few of the builders.

Cheers

Chris

Phil Cooke30/03/2020 21:24:57
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2449 forum posts
1703 photos

Yeah - I measure 175mm around where the canopy hoop would be. I need quite a bit off each side still!

Phil Cooke31/03/2020 08:27:21
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2449 forum posts
1703 photos

Some significant progress this morning even before getting out of bed! smile d

Postie brought home the taylor-made self adhesive vinyl decals produced by Callie Graphics in the US. A quick check and everything is exact on scale and font just as per my order - many thanks Callie - another brilliant job!

decals arrive.jpg

Phil Cooke01/04/2020 19:39:34
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2449 forum posts
1703 photos

Milling out the exhaust pipe to the rear face of F10. What would we do without the Dremel??

Rough shaping with a small milling cutter...

exhaust 1.jpg

Cleaning it all up and close to size with a bigger grinding wheel...

exhaust 2.jpg

Final shaping was done with a home made hand too - a small length of plastic pipe with some grit paper glued to it!

exhaust 3.jpg

End result if fairly pleasing, I've left the wall thickess at 3mm for now - it needs a bit more thinning out but will do that once the outer surface has been glassed for robustness I think...

exhaust 4.jpg

Edited By Phil Cooke on 01/04/2020 19:40:40

McG 696901/04/2020 19:48:19
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3027 forum posts
1144 photos

Superb craftsmanship as usual, Phil.

Did you have some progress with your canopy height already?

Cheers

Chris

Phil Cooke01/04/2020 20:17:01
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2449 forum posts
1703 photos

Hi Chris,

Having taken the measurement and compared it to yours - I've not cut it back yet, but by eye and with that measurement in mind it needs another 5mm or so off the bottom edge I think... I'll keep at it.

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