F-86 Sabre in Korea (SAAF)

[Cheetah11]

Hi Sean

Great to see you back again at the modeling bench. I assume the house painting is done.

Cheers

Nick

[tomg]

Great work so far.  Love the scratchbuilding - can't wait to see paint!!

[Violator1991]

Very good scratchbuilding. Very sharp and clean 

[IainM]

Those seats must have been quite uncomfortable to spend long missions in.....

Nice work as always!

[TimW]

Oh, this is cool.  I recently dug my Hasegawa F-86 out of the stash...and plan to do a SAAF as well!

 

Will follow this with interest!

 

Tim W.

[Madmax]

Glad it brought back some memories Derek. I imagine you are no stranger to Martin Baker and Irvin, which in turn (and thanks to the work of our survival equipment professionals) saved a couple of my friend's lives. I can still recall the feeling of strapping on a Martin Baker seat as if it were yesterday, even though it has now been more than 20 years since I last had the privilege!

 

Nick, the painting of walls is done for now, but I have been away from the bench again - installing flooring... 

 

Thanks Tom and Violator, the scratch building of detail is one of my favourite aspects of the hobby.

 

The seat looks pretty uncomfortable to me too Iain. Luckily the Sabre didn't have great endurance - and I recently read that it was fairly commonplace for guys to dead-stick back into their base airfields! 

 

Never too many Sabres Tim, and I see another has just arrived on the scene...

[Madmax]

As per usual, the drawings one bases measurements on need to be accurate, and good F-86 blueprints are very difficult to find. Based on a cross section of those I have found, and photographs, this is the piece of the elevator that should be removed to get the proportion correct.

 

 

Here is the final product (on the right), compared to the original and the Kinetic part.

 

 

The elevator was separated from the stab and its leading edge rounded along with scalloping the stab trailing edge. The rudder was built up a bit in order to give it a rounded leading edge too.

 

 

With the tail feathers taken care of, it was time to get stuck into the wings. Maybe its the age of the kit, or the size of the lower wing moulding - but man is it ever warped! It looks like a poppadum fresh out of the microwave oven.

 

 

All of the longer wing parts are warped, so I popped them into hot water and proceeded to bend them into a flatter state. The slats didn't like the treatment much, and one broke up into its constituent parts.   There is quite a bit of work planned for these distinctive features! 

 

 

The wings of the SAAF's F-86F-30's were (with one exception) the early slatted narrow-chord wing. This means that I will have to remove the "6-3" extension from the leading edge, as well as the 12" tip extension of the F-40 wing.

 

 

I am planning to remove the leading edge at the point where it is attached on the real aircraft via a spanwise toothed piano-hinge. The panel line indicated in the oval should move to the tip join.

 

 

Removing the "6-3" extension means the whole shape of the wing-fuselage join at the leading edge changes too. This presents a real head scratching problem.

 

 

Since real Sabres look like this with their wings removed, I figured it might be the way to go with the model too. It is a fascinating wing join - looks like the wing centre section is bolted onto a box like structure in the fuselage. No visible spar? (Photo borrowed from the AMARC Experience website)

 

 

Now that the centre section is removed, it is a bit easier to work with. First the wheel wells can be detailed (the etch is from the Eduard set, since the kit doesn't include the brake housing at all).

 

 

There was a bas relief attempt at detail for the wing portion of the well, which was scraped off and some styrene added instead. Seems as if I only ever do wheel wells...

 

 

 

Cheers,

 

Sean

[Madmax]

 

Yup, that's where I have been - probably still am.

 

The Hasegawa wing isn't ideally suited for conversion to a narrow-chord slatted one, but it will have to do. I really don't like the way the slat tracks are represented in the kit, so this was one of my first considerations. Based on a multitude of photos of slat tracks, and the structure of the model wing - I came up with this idea (this is just a styrene prototype of what I would like done in etched brass).

 

 

This requires a roller of sorts inside the leading edge, and here is my solution.

 

 

With that in place, it was time to join the wing halves. You will notice that there is no structure inside the wing to maintain the airfoil apart from the leading and trailing edge joins. Because of this I opted to first join the wings, and then perform the next major surgery, which is to remove the 6-3 leading edge extension. The slat track openings on the kit wings run very far back, and I was concerned that due to the lack of structure the leading edges would not survive the surgery. At this point I added styrene fillers to the overstated slat recesses in the hopes of propping up an otherwise wobbly affair.

 

 

Now to remove the 6-3 extension...

 

 

Job done, but to my surprise, the kits upper and lower separation lines for the leading edge don't match up. I was hoping to sand the opened leading edge joins flat, and emulate the attachment of a non-extended leading edge as it was on the real Sabre. No such luck.

 

 

 

Pity, but in order to retain the airfoil shape, I joined the leading edges as cut. Then came the job of scribing the detail on top of the wing. although I followed a lot of Hasegawa's detail on the fuselage, it would be wise to look carefully at the wings.

 

 

Understandably, a kit from the 1970's was predicated on drawings from that era. Many of the panels on a wing are based on the line from which it is squared on. On a tapered swept wing it is hard to guess what the datum is, so detailed photographs (or the real thing) are a must!

 

 

This one, is anyones guess...

 

 

I'll leave you with that thought for now, and on the next instalment, explain what has happened in the rabbit hole so far. 

 

Cheers,

 

Sean

[Madmax]

At first, I thought the slat issue was quite simple.

 

Based on the majority of slat track photographs I have "mined" from the internet, I sent off this simplified design to to a local etching company.

 

 

 

I was lulled into believing that all slats were created equal thanks to evidence like this... (there are eight "actuators" btw)

 

 

and here is a part catalogue drawing to support what I thought was the standard part.

 

 

In essence, the slat track is thicker above the slot than below. Then I started to see other evidence.

 

 

Thicker below. Sure, this is a VERY early F-86, but it got me thinking.

 

This photo in the Thompson book piqued my suspicion. An F-86 F crash reveals a slat track that is thicker below the slot, more like the early wing. The tracks are slightly bent from the impact, but the inspection panels on the leading edge confirm the orientation.

 

 

 

So what is going on down here in the rabbit hole?

 

Jennings Heilig created this guide to the basic differences between Sabre wings, and many of you with an interest in the subject would have seen it already. It is excellent for pointing out the basic differences, but he warned on the forum (that it was originally posted on), that the subject deserves a book. Agreed.

 

 

Here are some more differences that I started to notice. The slots in the leading edge are different, and this one is like the Korea Sabres.

 

And this one is not.

 

 

The shape of the leading edge of the early Sabres also caught my eye - they are quite rounded, blunt if you like.

 

 

And this one is sharper...

 

 

This may be more difficult to prove in court, but I think I can see it... 

 

I'll get to the point in the next episode.

 

Sean

[jenshb]

If I should hazard a guess, I'd say the 6-3 wing has the sharper leading edge to allow a smooth transition to the existing aerofoil after extending the leading edge.

 

Good craftmanship and research here - thanks for posting.

Edited June 1, 2021 by jenshb

[Madmax]

21 hours ago, jenshb said:

If I should hazard a guess, I'd say the 6-3 wing has the sharper leading edge to allow a smooth transition to the existing aerofoil after extending the leading edge.

 

Good craftmanship and research here - thanks for posting.

 

Thanks Jens.

 

I agree with you - the deeper leading edge of the 6-3 extension necessitated a different airfoil section. This had a notable impact on the handling of the aircraft (particularly the initial hard wing).

 

 

 

Here is a good reference for Sabre fans:  https://finescale.com/~/media/files/pdf/online-extras/sabre/sabretable.pdf

 

In the table I found the answer I was looking for, at least for a Korea F-30.

 

 

So, the SAAF's Sabres had a late A-5 wing with new inner hardpoints! The important thing for me is that it had the same slat tracks as the F-86A. This is what they look like...

 

 

This means that the slat tracks I ordered are wrong. 

 

That was bugging me - a lot, so I ordered some new ones. Pricey hobby! 

 

 

It's not often one gets to see this leading edge without the slat attached. I was surprised at how sharp it is, certainly compared to the truncated representation in the kit.

 

 

 

I risked sanding it to the same fine edge, but there just wasn't enough plastic to pull it off. I then resorted to shoving styrene into the compromised sections - not very tidy but it has saved the project from the bin for now...

 

 

It looks a bit better after initial shaping.

 

 

Enough of that. I was wondering about the incredible complexity of the various modification states of North American Aviation products in the 1950's, and the staff required just to do the admin! Maybe this is how it was?

 

 

I messed with the photo - just having some fun. 

[MikeMaben]

Lookin' good Max, thanks for all the pix 

[dodgem37]

Great research.

 

Sincerely,

Mark

[Madmax]

 

Well, there it is. A problem shared 

 

 

 

Now I can get to grips with establishing a sound method of attaching the wings to the fuselage. A problem entirely of my own making of course, since you may recall that the kit had a single piece lower wing. Part of the challenge, as with the wings, is the absence of structure to hold the airfoil shape in place. This has caused many difficulties with the wings in particular as they tend to squeeze and crack when being worked on. All part of the engineering challenge, and we do this for fun after all - don't we?  

 

 

 

I had to pause work on the wings at this point as I wait for the etched slat-tracks to arrive. A good time to address the main gear, which is very basic in these old kits. The Hasegawa legs (the lower ones) have nasty ejector pin marks, and the wheel axle in the centre of the leg. As per the Kinetic legs (above), the axle is offset in a trailing position on the leg. I would have preferred using the Kinetic legs, but the mounting pin is just not compatible, and not something I like to compromise when modifying a kit.

 

 

Here is an improved leg, and some of the components (including the torque-links) that were made from stryene pieces.

 

 

The Hasegawa wheels are ok, but the side facing the leg could be improved. The Kinetic hub looks much closer to the real thing, so I opted to use it instead. The Hasegawa brake drum is nicer to my eye, and is easily upgraded.

 

 

 

 

 

Here the final product...

 

 

Back to the slats shortly.

 

Cheers,

 

Sean

[scvrobeson]

Fascinating fixes and improvements for the kit.  Really enjoying the work to bring this one up to modern standards.

 

 

 

Matt