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Chris McG F-86 Sabre Dog build blog

my first attempt to a soaring bird for the PSSA MB 2020?

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McG 696928/07/2020 19:56:43
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3368 forum posts
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Hello all,

The crucial moment that I need some help has come, especially from Phil as it concerns the aileron torque rods which I’m copycatting from him… blush

I’ll try to be as clear as possible with my - hopefully not too stupid - questions. angel

Hence, I prepared this in b/w pic as it shows the coloured lines better >

1416_torque_rods01.jpg

My questions are:

A > the SLEC torque rods came with that strange horn (left on the pic) that I replaced with the same as Phil (right on the pic). Is that OK?

B > concerns the position of the angled part of the rod. It seems to be +/- half of the distance between R1 & R2?

C > how much is the height of that angled part? I guess measured from upwards the top sheeting is easier with an already built up wing? Does it need to be shorten?

(continued)

McG 696928/07/2020 20:00:05
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3368 forum posts
1287 photos

(continued)

Now we come to the totally daft one. This is Phil’s wing center section in b/w.

1417_torque_rods02.jpg

D > if I screw both ball links on the interior of the horns, the angle with the torque rods will be less, ie. closer to perpendicular. I keep thinking that the ‘arc’ that Phil mentioned would be less in that case…

Sorry, Phil… told you I would need help soon. blush

Already looking for a tin hat and an appropriate concrete bunker…

Hakuna matata & stay safe, all

Chris

BRU - BE / CTR Daft Questions Control

Phil Cooke28/07/2020 21:35:07
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2649 forum posts
1851 photos

Hi Chris,

I can answer your questions but its worth pointing out my 'chosen' dimensions and final general arrangement are not that critical, what I can point out are the concerns I had in mind when sizing and positioning the torque rods which led to the finished result.

Your questions;

A > the SLEC torque rods came with that strange horn (left on the pic) that I replaced with the same as Phil (right on the pic). Is that OK? Absolutely ok - best i think to make the horn as simple and as small as possible - we only need a single hole to mount the ball link and nut.

B > concerns the position of the angled part of the rod. It seems to be +/- half of the distance between R1 & R2? I've just measured mine at 17mm outboard from the centreline - see photo.

C > how much is the height of that angled part? I guess measured from upwards the top sheeting is easier with an already built up wing? Does it need to be shorten? Yes, I shortened it - see photo - it results in 20mm sticking up proud from the top sheet, which must mean 25mm from the 90deg bend. Again, photo attached.

answer1.jpg

answer2.jpg

My concerns in positioning and sizing were simply I wanted to minimise the risk of internal binding when they are working, not only between the torque rods and the wing bolt plate (which I had relieved to create a suitable working volume) but also with each other as they would be operated not only as ailerons, but also as Flapperons and Dragerons when required. Flapperon (with the wing sweep) sees the two torque rods move closer together - this gets worse the longer they are and the closer they are together.  These concerns led to the 17mm outboard spacing and the 25mm height seem about right... all now tried and tested too.

But there is no rocket science behind it really.

Edited By Phil Cooke on 28/07/2020 21:37:26

Phil Cooke28/07/2020 21:43:57
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2649 forum posts
1851 photos

D > if I screw both ball links on the interior of the horns, the angle with the torque rods will be less, ie. closer to perpendicular. I keep thinking that the ‘arc’ that Phil mentioned would be less in that case…

Yes this to all true and you are right the perpendiclar arrangement is superior mechanically speaking, although not that critical on a relatively lightly loaded model like this. Again, I simply went outboard as opposed to inboard to ensure there is no risk of clash when the torque rods are operating. Having them inboard to me just increased the risk of a clash especially when some flap is in play. Of course you could move them out a few mm more from 17mm to say 20mm. You'd save a little weight on the torque rod that way too.

As you can see in the plan view below, having them outboard doesn't take them that far off perpendicular - but the 'arc' is real across the full throw extent, and for that reason I agree inboard is more refined. Just watch they don't clash!

answer3.jpg

McG 696929/07/2020 08:54:23
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3368 forum posts
1287 photos

... wauw... lightning fast and fully comprehensive... surprise

Thanks a lot, Phil, for the amount of energy you spent on answering me.

With the proper info and pics, it all seems sóó easy.

I only have to follow the 'Chief's Manual' now... wink

Cheers & thanks again

Chris

McG 696929/07/2020 20:11:57
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3368 forum posts
1287 photos

Hello again, gents.

I was getting on with the measurements for the positioning of the torque rod bearings, when I realized that I might be missing some substantial balsa between the R1 & R2 wing false trailing edge. indecision

That will be needed to create the channelling for the vertical part of the torque rods as the false TE isn’t really thick enough.

I had some earlier build pics on the tablet but to make sure, pricking with a needle into the top sheeting resulted in a pure ‘hole’…

1424_blocks_bodging_900.jpg

A bit of surgery later and after the preparation and introduction of some fresh balsa bits, the case was resolved, but I lost the nearly full length of my session to ‘rescue’ this omission.

Final sanding after the glue will have cured.

Let’s call it part of the learning curve… blush

Hakuna matata & stay cool

Chris

BRU - BE / CTR Omission Control

McG 696930/07/2020 20:28:17
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3368 forum posts
1287 photos

Hi there,

Slowly starting to get the bits ready to compile the ailerons with the fixed part of the wing TE.

Not quite there yet, but I thought of having the aileron hinges a bit concealed.

If I can manage that, it would be a nice addition to Phil’s torque rods with no appearing rods and clevises. yes

I thought about Danny F’s solution for his Chipmunk Masterclass some years ago.

Instead of filling up the aileron LE area with triangular concave shaped parts, he filled up the ‘empty space’ with thin ply over the hinge knuckles. cool

I’m going to use 1/32 ply - as I don't have any thinner - I need a recess of +/- 0,9mm on the aileron part of my wing.

As I don’t think I could be that precise, I made up another home-made tool consisting of a piece of square angled styrene, a thick ply handle and two laminated strips of 120 grit and 8mm wide sand paper.

1427_hingeshroud_tool01_900.jpg

(to be contnued)

McG 696930/07/2020 20:32:08
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3368 forum posts
1287 photos

(continued... but really silly software here on the forum)

When dry, of course I couldn’t stop myself from testing the ‘thing’ on a scrap bit of balsa.

In fact, it's dead easy and 'automatic' as when the sandpaper stops its job and you're just 'sliding' the styrene over the balsa, the job 's done...

1437_hingeshroud_tool02_900.jpg

Seems to work smoothly enough... the 'tool', not the local software… angel

Hakuna matata & stay safe, all

Chris

BRU - BE / CTR Recess Control

Phil Cooke30/07/2020 21:01:10
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2649 forum posts
1851 photos

I like it! - very nice work! I look forward to seeing the finished arrangement! thumbs up

McG 696931/07/2020 09:30:44
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3368 forum posts
1287 photos

Thanks, Phil.

Comments are always quite rewarding and motivating... wink

As this is a 'première' for me (again !), I'll ask you to be a bit patient.

Especially that we have a mini heat wave here in BE with forecast temps over the 35°C... hot

Cheers & stay 'cool'

Chris

McG 696902/08/2020 18:50:11
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3368 forum posts
1287 photos

Hello out there,

Sometimes one has to take a bit of distance from the building board.

I thought inserting some time for pondering during the WE was on the order.

This included some BBQ-time and obviously the British Grand Prix, even with the 'bad-luck-forfait' of Hulkie...

Mentally ready for La Grotte now, starting tomorrow.

Cheers & keep safe, gents

Chris

Phil Cooke02/08/2020 20:32:24
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2649 forum posts
1851 photos

Well, enjoy your weekend! - you have a bit more time to complete your masterpiece now Chris, I assume you have seen my note here in the forum and on the PSSA website about the deferral of our Mass Build until 2021...

But like Lewis with his delaminated tyre, don't take your foot off the gas too much! - it will soon be May!

McG 696903/08/2020 09:26:24
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3368 forum posts
1287 photos

I had a relaxing weekend, thanks Phil.

... that is despite my race predictions on Fantasy GP were lousy as my team members got 'tyred' as well... frown

Ailerons & torque rods, here we come... wink

Cheers & stay alert

Chris

McG 696903/08/2020 20:10:58
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3368 forum posts
1287 photos

Hi again,

Back to the aileron shrouds then.

Not a lot of words as the ‘tool’ worked as planned… cool

1440_hinge_shroud01_900.jpg

I then prepared the four 0,8mm ply shrouds, cutting them simply with a steel ruler and a Stanley knife.

With a new blade, only three light passes are all it needs to obtain a clean cut.

1441_hing_shroud02_900.jpg

This is just a dry test as it will need a bit of sanding and inside tapering towards the aileron LE to minimize the risk of binding.

Anyhow, I can already foresee a lot of adjustments before gluing everything in… frown

@ Phil > oops, forgot to answer you, but yep, I’ve been reading about the postponement of the Sabre’s Orme fly-in to next year. So, I might be ready by then… angel

Hakuna matata & stay alert, gents

Chris

BRU - BE / CTR Shrouds Control

McG 696904/08/2020 20:17:20
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3368 forum posts
1287 photos

Hello out there,

Still a bit too warm here in BE...

Nevertheless I managed to have some progress with refining/sanding back the aileron ply shrouds.

Also managed to have the port and starboard torque rod bent to shape and drilled the port aileron TE accordingly, I hope. indecision I might then proceed with the second one...

As foreseen, every bit now needs to be adjusted till we get a nice fit.

Pics to follow sooner than later... cool

A few matata here, but stay safe all

Chris

BRU - BE / CTR Adjustments Control

Phil Cooke04/08/2020 23:08:34
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2649 forum posts
1851 photos

Hope you didn't forget to slip on the plastic bearers before you added the bend to the rods!! Been there!!

McG 696905/08/2020 18:43:38
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3368 forum posts
1287 photos

Thanks for bringing a big smile here, Phil.

I can't imagine the Chief forgetting his torque rod bearers though... but then even Peter M admitted making two left fuselage sides in his earlier times. frown

I was very lucky this time as I even taped the plastic bearers to the rods. cool

... and if somebody is wondering, I even managed to distribute the bearers equally to their respective rods... four at each side, IIRC... angel

Cheers & keep cool everybody

Chris

McG 696906/08/2020 19:00:46
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3368 forum posts
1287 photos

Hi to all still present,

Slow progress, but still progress. The high temps - 29 > 30°C - inside La Grotte are very probably a main factor as it makes it a bit hard these days. hot

I had the hinge shrouds adjusted and glued with Aliphatic, both port and starboard.

1445_hing_shroud_900.jpg

The port torque rod went in with epoxy on the bearers.

Please note the presence of the correct four bearers here… angel

1449_torque_rod_900.jpg

And the session was completed with the fixing of the starboard torque rod.

This one must have four bearers as well as I only had eight to begin with… cool

1453_torque_rod02_900.jpg

Then it was time for a well deserved apéro… make it a couple of them just for ‘cooling down’ purposes… cocktail cocktail

Hakuna matata & stay safe all

Chris

BRU - BE / CTR Temp Control

Dwain Dibley.06/08/2020 19:31:56
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1523 forum posts
1506 photos

Cosmic Stuff Chris, nice to see it progressing young Man !!

Got to be 30 deg here tomorrow, so a hot commute on the bicycle for Dwain. crookhot

D.D.

Phil Cooke06/08/2020 19:56:45
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2649 forum posts
1851 photos

lovely job Chris, very neat and tidy...

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