Rubber-Powered Fairey Barracuda

[AndyB]

I designed this 24" span Fairey Barracuda for rubber power a few years ago; it started out as a simple 1.5x enlargement of my Dime Scale plan that was covered on HPA2, but it eventually turned into a more-or-less complete redesign. I've done it as FAC "Simplified Scale", so it's relatively simple and some of the finer details are missing, but I've tried very hard to make the overall outline shape as correct as possible, given that it's meant to be a flying model.

Getting the outlines correct has been difficult because some of the existing drawings are not very good (e.g. Hall Park Warpaint #35). I've gone with the (very small, quite basic) drawings from "The British Bomber since 1914" by Peter Lewis (pub. Putnam), simply because it seemed to have outlines that matched the available photographs.

One of the main areas of disagreement between drawings and photos is the leading-edge at the wing root – some drawings show a discontinuity in the leading-edge shape but I can't convince myself that it shows up in a "proper" top view; there is a discontinuity but I think it's basically an increase in the (already significant) wing thickness around the wing fold break. Needless to say, I haven't found a photograph that is sufficiently close to directly-above or directly-below to resolve the issue. There isn't an existing airframe available to examine, although I think one of the well-known museums (Hendon/IWM/FAA Yeovilton?) has plans to re-build one from various donor airframes and parts.

There have been the usual minor increases in area and dihedral because I want it to fly for as long as possible; I hope these changes don't change the character of the model too much - they'll probably pale into insignificance when set next to the much-thinner-than-scale airfoil that I've had to use.

All that's done so far is the tail surfaces that you see here, but I'm going to try and focus on this for the next few weeks and we'll see how long it takes; I'm not a quick builder, but as the thing has made it to the front of the build queue I might as well get on with it.

[TheLurker]

And about flamin' time too.

[AndyB]

And about flamin' time too.

Hahahahaha!

Mea Culpa.

But I suppose this'll be similar to your peanut Hurricane, won't it? You started that at about the same time I started this, but I don't think anyone has ever seen a completed plan... ??  Or any plan, come to that. 

[TheLurker]

...But I suppose this'll be similar to your peanut Hurricane, won't it?...

It's going to be my retirement project.  

[OZPAF]

Don't plan on having too much time in retirement Lurk It didn't work for me!

You might just win this race Andy!

Interesting subject anyway.

John

[AndyB]

Started on the wings which will plug into the centre section using a couple of 1.6 mm carbon rods in 3/32" aluminium tube. At some point I realised that the wing attachment ribs weren't going to be strong enough to resist the pull of the covering, so had to re-draw and re-cut a couple of ribs; this is usually the way of things, everything looks fine when viewed through my rose-tinted designer glasses, but reality usually hits when handling the actual parts.

I am, however, prepared to admit that I might now have over-specified them - they're the two really thick (1/8") ribs in the picture below.

[AndyB]

Got the wings finished and joined, although I do still need to do the flaps and flap runners before moving on the the fuselage.

I haven't weighed anything yet because there's nothing I can do about it when I find out that it's turned out a bit heavy...

[Squirrelnet]

Very nice Andy. I like your removable wing mounts, very neatly done

[OZPAF]

Are you using bent joiner wires in the aluminium tubes Andy? It seems to be indicated in your pics but you mentioned using carbon rods?

Regardless - light and clean structure as with all your builds.

John

[AndyB]

Are you using bent joiner wires in the aluminium tubes Andy? It seems to be indicated in your pics but you mentioned using carbon rods?
<snip>
John

It's actually four straight 1.5 mm carbon rods (slightly doctored, see below) running in 1/16" ID aluminium tubes; I did think about using 1/16" wire but the weight penalty was fairly horrific for a 24" span model. As it is, there's about 10 inches of tube and a little less carbon rod, so the penalty should be 2-2.5 grams depending on how much rod gets used and whether the selected magnets are up to the job of keeping the wings in place.

The carbon rods are wiped with a bit of thin CA and then carefully sanded back, I think I'll probably give them a quick (very thin!) coat of waterproof acrylic varnish to make a better fit in the tubes; might be able to do without the magnets.

A.

[OZPAF]

Thanks for that. I guess my head is still in the kG area of models and not the gm size as far as joiners go

John

[AndyB]

It's always the detail bits that slow you down - the flaps are finished but are not as-drawn because apparently I'm still changing things as I go. Flap runners are also re-designed so had to print some more parts to be cut.

Off flying tomorrow and I'm busy on Sunday, so should get back to this on Monday.

[AndyB]

Removable wing panels are sorted, pictures should be self-explanatory although I find sanding the ply end-panel facing down to match the wing section quite stressful - almost as stressful as drawing control surfaces, there are just so many ways it can go wrong. Wing root magnets are 3mm x 1mm which look to be just strong enough.

On with the fuselage tomorrow...

The only slight cloud on the horizon is that I've weighed everything and it's about 16.5 grams (of which about 2.5-3 grams is for the removable wings), so far; even if the fuselage doubles that total, there's a decent chance that the finished empty weight will be sufficiently low that it'll need a dethermalizer, which I was hoping to avoid.

The only sensible approach to installing a D/T is, I think, to break the stabiliser at the main spar and tilt up the rear half 90 degrees, as on Tom Hallman's Schweizer SGU 2-22. It's not a scale elevator break line but we do want the thing to come down on demand.