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Avon Sabre Spirit 78

CA-27 Sabre of Indonesian Airforec display team

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Steve Houghton04/11/2019 12:56:22
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572 forum posts
420 photos

tniau_f86.jpg

My subject for the 2020 PSSA mass build is this scintillating CA-27 operated by the TNI-AU or Indonesian Airforce Display Team, known as Spirit 78. This is a modified variant of the F86-F but powered by a Rolls Royce Avon engine (it's British, don't you know!). The fuselage was deepened and the intake widened, but I shall be exercising builder's licence to just use the standard plan version because I like the colours.

It was faster than the US versions, and sported twin 30mm cannons instead of the usual 6 machine guns - handy if the crowd gets nasty during a flying display!

If I can master the painting of the curves, it should look something like this:

da144001b.jpg

da144001c.jpg

Martin Gay04/11/2019 13:14:36
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379 forum posts
254 photos

Nice! I've not seen that scheme before.

Andy Meade04/11/2019 13:15:37
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2760 forum posts
717 photos

hehe - excellent introduction there Steve laugh Great colours too!

Steve Houghton04/11/2019 23:10:47
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572 forum posts
420 photos

Thanks, Guys. The first fuselage half is well under way. I hope to post a few pics tomorrow,

Steve Houghton05/11/2019 21:42:02
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572 forum posts
420 photos

Wing Bolt Plate

Doing a dry fit of fuselage parts I noticed that WP1 as cut in the kit, and shown on the plan view, does not butt up flush against F7 when inserted into the slots in F14. I therefore cut 3/16" off each tab and epoxied the bits onto the front, to move the tabs forward and allow WP1 to sit back against F7.

pb030412.jpg

It now fits flush, and could be reinforced with triangle strip if necessary:

pb030413.jpg

I believe this is correct according to the fuselage side view of WP1:

pb050428.jpg

Side by Side

I then ploughed on with assembling the first fuselage side. I chose to laminate the bottom keel from two pieces of 1/8 x 1/8 to create the curvature, and to align and glue the formers against this before adding the top keel:

pb030418.jpg

However, this resulted in a slight mis-alignment of the tops of the formers with the top keel, which is straight. I lengthened the slots in F9 and F10 to the same 6mm width as the keel, and managed to get it all to fit:

pb050421.jpg

pb050422.jpg

The only small issue I had was trying to hold down the part-formers F3 and F5 and keep them vertical. I therefore fitted them at the same time as adding the stringers, and applied suitable weights onto the stringers (not shown).

pb050425.jpg

Now onto some planking.....

Martin Gay05/11/2019 22:34:15
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379 forum posts
254 photos

Looking good Steve.

Harry Twist05/11/2019 22:46:08
356 forum posts
270 photos

Looking tidy that Steve, nice choice of scheme also. Your intro has got me wanting to read up on the Avon Sabre - didn't realise fitment involved fuselage mods!

Steve Houghton06/11/2019 00:15:20
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572 forum posts
420 photos

Thanks for the comments.

Harry; Mark has posted a few videos of the CAC Avon Sabre, on his Sabre F86 thread, if you want to see more.

Meanwhile..

Get planking

I have never planked before, so this is a step into the unknown. Where to put the first strips?? I decided to put them straddling the central stringer. They don't follow the stringer route exactly as I allowed them to 'relax' into place without too much twisting and resultant in-built tension in the frame. I am trying to use tapered planks, approx 8mm in the middle, tapering to 5mm at the nose and 3mm at the tail. Whether this will work for all of them I don't know but it'll be exciting finding out:

pb050435.jpg

pb050433.jpg

Accommodating the sharp tail curvature is going to be the biggest challenge, hence the narrow strips:

pb050432.jpg

Steve Houghton08/11/2019 18:38:48
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572 forum posts
420 photos

Part Planked

One complete sheet of 1/8 x 3 x 48 has now been dissected into thin tapered strips and applied to the fuselage. The nose and tail now look like this:

pb080437.jpg

pb080436.jpg

The tapered strips are working well, but I don't yet know if they'll be practical as the curvature tightens up.

pb080438.jpg

Tracing the way ahead

I'm going to start the second fuselage half before completing this one, so that I can check that the two halves align accurately. Just visible in the photo above is a sheet of tracing paper underneath this half. I traced around the framework and then laid it upside down onto the second fuselage half on the plan to check that everything was going to line up. There are minor discrepancies, as expected, but I'll build onto the tracing to hope they match:

pb080441.jpg

I think the main aim is for the two halves of F4 and F7 to align accurately at the wing seat, where fellow F86'ers will be able to spot any mistakes!

Martin Gay08/11/2019 19:44:52
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379 forum posts
254 photos

Steve,

If you leave the last few planks off at the top and bottom of each side it will be easier to align the two halves.

Clamps can be used along the keel pieces whilst the glue dries as well.

Don't forget to add the battery box and WP1 before joining the fuselage!

Martin.

Steve Houghton09/11/2019 00:39:25
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572 forum posts
420 photos

Thanks, Martin.

I did wonder about leaving the last planks until after joining, but with the aim of smoothing over the join line. I'd forgotten about being able to clamp them, so thanks for the reminder.

Steve Houghton10/11/2019 17:16:44
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572 forum posts
420 photos

Dry Bones

The basic frame of the RHS fuselage has been assembled and dried overnight without any planking. I couldn't resist a dry fit of the two halves to check the match.

The top of the nose looks OK:

1911_1001 dry fuz top.jpg

The cockpit area is reasonable:

1911_1002 dy fuz cockpit.jpg

F1 and F10 are nicely square and in line:

1911_1003 dry fuz f1.jpg

1911_1004 dry fuz f10.jpg

Overall, the wing seat is acceptable, in that the centres of the formers line up:

1911_1005 dry fuz wing seat.jpg

However, F7 and F4 are slightly angled. I think I was too zealous in sanding the ends of F14 on the first half, resulting in shortening it a fraction. I didn't notice during the dry assembly of the second side, but the second F14 must have been a fraction longer and caused F4 and F7 to be slightly splayed apart when I aligned their inner edges with the tracing of the first side. Here's the backwards kink in F7:

1911_1006 dry fuz f7.jpg

Similar kink forwards in F4:

1911_1007 dry fuz f8.jpg

One side of F4 is therefore a little crooked, where the light is shining through below. I might have to apply a thin shim of wood to level the rear edge a bit, but that'll come later.

1911_1008 f8 alignment.jpg

Work Assessment

Overall, 7/10 so far for effort, but could do better.

I'll return to planking for a few days now.

Phil Cooke10/11/2019 18:14:22
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2530 forum posts
1784 photos

It all looks very neat and accurate to me Steve - great progress... seems the fuelage comes together quite quickly - impressive stuff!

I'm still fettling the Jet Provost 150 here so not planning to make a start on my Sabre quite just yet - but I'm conscious of being left behind!

Steve Houghton10/11/2019 20:20:06
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572 forum posts
420 photos

Thanks Phil,

Yes, the fuselage is a very satisfying build, which I am really enjoying. Great design work by Martin and Gordon.

In case the message is hidden in my last post: I recommend builders to check that F14 is the same length on both fuselage sides, after you've fettled it to fit the slots in F4 and F7. I'm not suggesting any problem with the kitted parts, just my finger trouble.

Phil, I'm jealous of your masterful work on the JP canopy. I've revisited my Zlin 526 canopy recently, without much success yet - I'll post an update when I can (completion will soon be as late as your Hog!). Perhaps you should offer an article to RCM&E about your method - it always seems to achieve stonking results.

Chris Barlow11/11/2019 02:04:38
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1904 forum posts
1308 photos

I'd give you at least 8/10 for effort Steve. Good tidy progress there. yes

I have added some beginner friendly tips for planking on my blog if you need any entertainment! laugh

Steve Houghton11/11/2019 12:53:28
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572 forum posts
420 photos

Chris, Thanks for the 10 planking tips - very useful.

I've planked as far as the edges of the tight corners, and not sure I can twist the planks round without tapering. It may be a case of much narrower planks, almost strips, to negotiate the curvature.

Martin Gay11/11/2019 12:59:51
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379 forum posts
254 photos

Hi Steve,

I chose to use a herringbone type pattern and trim the planks to fit where they touched!

img_2947.jpg

Steve Houghton11/11/2019 13:06:20
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572 forum posts
420 photos

You experts all make it look so easy!

Martin, I note that you have left the wing seat unplanked - I was wondering about that, and precisely how to cut out the wing seat area. Perhaps you could elaborate on the Gamma build blog, when you come to it?

Steve Houghton17/01/2020 19:41:51
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572 forum posts
420 photos

Running (walking!) Again!

Following an unexpected delay to building, my progress continues slowly. Both fuselage halves are now planked apart from the gaps for joining, and the wing seat. The photos show my tapered planks, seemimgly much narrower than other builders have used, but it worked for me.

The tail end:

2001_1701 tail planks.jpg

Wing Seat:

2001_1702 wing seat.jpg

Lower nose:

2001_1703 lower nose.jpg

Upper nose:

2001_1704 upper nose.jpg

That sinking Feeling

A few planks sank and ended up looking 'starved', so I just layed a few strips of 1/16 to fill the depressions:

2001_1705 sunken plank.jpg

Making two halves into a whole

I'm thinking through the fuselage joining phase. I plan to use closed loop for rudder control and will install a couple of tubes to guide the cables, once I decide where the servos will go.

For elevator control I'm planning to use a solid pushrod. I've done a few dry runs and believe I can install it after joining the two halves. There is enough wiggle room to poke the rear end up through the slot for the bellcrank, couple it up and then fix the crank into position. That's the theory! If not, I'll need some surgery to open a hole in the fuselage.

McG 696917/01/2020 20:23:53
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3142 forum posts
1193 photos

Hi Steve,

Nice to have you back at the building board... and already close to join your fuse halves. yes

Cheers

Chris

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