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Grumman American Cougar


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Looking very tidy Mark. That nose gear is lost in the fuselage, so much space.

Very professional job on the steering rod bracket. Down at my level I'd have thought plastic tube (snake inner/outer?) in a block of balsa, or similar...

As for axles, your creations there also very professional.

However, I am surprised you don't have a wire bender in your arsenal - they are worth their weight in gold and get consistent and accurately located bends. Plus you can wind coils, so making a replacement leg for a retract unit is not out of the question.

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Hi Gents,

Thank you all for your kind comments.

Nigel, I do have a wire bender, but I'm not confident of getting the bend in exactly the correct place, hence the engineered axles. I will weigh a couple of collets and a chunk of wire and see how it compares.

Once the steering mechanism is complete, I will upload a video of it in operation.

I got a bit more done last night and today. I glued the two laminated formers in with epoxy, they had both contracted by about 1/8" so needed gently splaying out whilst they dried:

2bc56bf6-5327-4ecd-8b00-b308db107811.jpeg

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Then i got the small strips and bits and pieces done ready for when the ply arrives and I can get it cut and on

53424eb0-55e0-47a6-a4a4-8c867a99178e.jpeg

Its getting a decent size now:

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Lastly, I got started putting a few laminations of soft 1/16 on the outside of the front former, this is to compensate for the rake and most of it will be sanded off, leaving just a fillet to glue the planking onto:

97ae2e07-1e9f-4037-8e42-9749462bbaa8.jpeg

Cheers

Mark

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I got that 1/16 compensation sanded down today. There is a little more to do, but its getting close:

5b4b965b-c511-4bbd-a8a9-a428be70232a.jpeg

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As I'm still awaiting the wood order, and the 1/32 ply for the side window pieces, I decided to start planking the rear, behind the windows. But before doing this, I wanted to get the fin front piece correctly slotting through F9. I cut a oblong hole in F9 before I fitted it, thinking I could sort out the angle sanding later. This took a while today, but it is now close enough that I'm happy to plank in the rear:

755a82cd-f64b-4c29-9aac-e0267d86b36b.jpeg

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I then measured up the front and rear of the tapered section at the rear of the fuselage:

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And then measured these, and worked out that each side would need 20 x 6.1mm planks, tapering to 3.35mm at the rear end.

I then made a start:

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I'm just going to carry on with these now, up to nearly the top of the windows, then the planks need to go all the way to the front former, until the windows go in, i'm going to hold off doing these. There probably won't be any more updates for a while, as until the wood arrives, its just planking.

Cheers

Mark

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Hi Gary,

Thank you for your kind comments.
As this is my first go at planking, I’m by no means an expert, but it appeals to me and I am enjoying it immensely.
It’s really just a stab in the dark, to see what works and what doesn’t. At the moment, it seems to be going OK. The front planking has sanded down nicely, and I’m very happy with it.

Cheers

Mark

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Thanks Martian,

I have been slowly plugging away at it in the last few days. Planking and more planking. To be honest, my fingers have been hurting, and being a fibre optic engineer, I was convinced that I had got a couple of slivers of glass in my finger tips. (it happens every now and then, and is very, very painful, and they are so small and difficult to see, even harder to remove.)

I then realised what had happened. As I have been sanding the bevels onto the planks, I have sanded my fingertips off......

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not quite as painful as fibre slivers, but not far off.

Here are a few photos of progress:

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Those 'stiffener' pieces are very fragile until they get planks on.

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That's about as far as I want to go, until I get the side pieces on (the stiffeners are going to need some work to get them to fit properly), and I'm still awaiting my wood order, so I put the fuselage to one side and got started on making up the fin and rudder.

This is the one part of the build that I haven't been looking forward to, and have been racking my brain as to how to approach it. In the end, I made up the rear tapered post for the fin and then made up a tapered packing piece, then packed up the front post so that both centre lines were in the same plane, then got started on it:

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I ended up using a mish mash of both plans, as the one on outerzone shows the lower fin block sitting on the horizontal stab, whereas, the paper plan shows it hanging in mid air, I started with the view that I was going to follow the paper plan, but then changed my mind and decided that the block sitting on the stab would give a greater gluing area.

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It turned out OK, not perfect, but passable:

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Then today, I have made up the rudder:

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Note to self..... don't sand off your fingertips. It hurts.....

Cheers

Mark

Edited By Mark Elen on 01/06/2020 21:41:00

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Strangely Mark, I did exactly the same thing late last week whilst wet sanding the primer on my Moth Minor. Didnt realise until I was just about finished and spent the next 2 days whimpering (in the most manly way possible onviously) whenever I picked anything up! First te I've ever done it, must be getting soft

Great to see your progress

Gary

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I have got a little more done today.

I hinged up the rudder and got the top piece glued into place:

f9b61437-8071-44bc-be75-525334ba8343.jpeg

It still needs sanding down to shape.

Then I got out the wing plan and traced out the horizontal stab profile and set to work drawing out a built up version. I'm not sure if my designing skills are up to scratch, but here it is:

a734f35b-7ed9-4069-9ee9-07a42492d1d8.jpeg

I'm going to have a go at it and see how it turns out.

Cheers

Mark

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Mark, do what you think best, your instinct seems pretty good, trust it.

I would not trust that plan. The whole design appears overweght.

Also watch out when it comes to epoxy strength and weight.

I did an interesting test on a Fury strut. One brass strut end attached to 1/16 ply with 30 minute epoxy, one with medium CA. I was very surprised how it was almost impossible to get the CA one apart, and it in fact split the ply. The epoxy was solid, but I was able to pop it apart.

Epoxy is old school......Hysol now you are talking.....

Cheers

Danny

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OK,

So, my instinct all along has been that this will turn out nose heavy, so I have decided to build the tail plane as per plan. If it turns out heavy, so be it. It won’t fly much anyway....I always say, 90% of my enjoyment of the hobby is building, rather than flying.

If it’s anything like my last effort, it will end up in bits (not of my doing) on its first outing.
I will laminate up the tailplane dihedral brace, as per Johns comments.

I have got the majority of it made tonight, but no photos.

Cheers

Mark

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Mark I would stick to your guns on the built up tail. It will resist warping better than a solid lump anyway.

I'd only suggest losing the rear spar and moving the brace back to the rear 1/2 x 1/4. Otherwise it looks perfect.

My choice for the braces would be lose the braces entirely and join the halves with some thin glass. It can be blended in quite easily. But either way will work

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