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Nigel R27/10/2020 11:34:56
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4298 forum posts
716 photos

I wanted;

  • quick easy build (so no fancy shapes or tricky techniques or whatever)
  • sized for a .46 or .60 two stroke, or a .70 ish four stroke, or thereabouts.
  • Or, potentially, a 4S5000 electric.
  • be able to some 3d type manoevers like hover and harrier
  • minimal new wood use - scrapbox / leftovers / foamboard, etc.
  • radio and servos from the drawer
  • easy to transport

Many moons ago I made an own-design fun fly type called FlapJack. This was in the early 90s when the 'monowheel and carbon tail boom' fun fly were appearing. I made one with a very basic box fuselage and conventional U/C, although it was like the contest fun fly types, all in one piece. I rather fancied having another similar model again. However that small fuselage wouldn't do a knife edge for toffee and the wing would need to be removable.

As another thing to chuck in the mix, around a year ago I made a Bigga Bit from a mix of foamboard and liteply and balsa, which has worked out really well, so some of the construction from that was to be copied/re-used/etc.

So.

I ordered some 1/16 to sheet the wing with, and a couple of sheets of 1/8 to make a fuselage with. Everything else is scrapbox or leftovers.

Ribs are all from foamboard. I stripped some balsa spars from some hard 1/4 and the LE / TE components from medium 1/4, and stuck the lot together with a standard D Box from 1/16 sheet.

20201012_160502.jpg

All quite conventional so far. 48" plank, in one piece, so I could use 48" sheets for the LE sheeting. As I only had 36" spar stock in the scrap box, I used that, and had to scarf join it toward the tip. More 1/16 sheet makes up the TE and caps, again all no surprises.

20201013_104001.jpg

Servos are dropped in between two closely spaced ribs. Quick and reasonably tidy, avoids having them hung right out in the breeze, just the arms poke out.

20201013_104009.jpg

Then I cut out some flat tip shapes from foamboard. These have some 4 lots of 1/16 x 1/4 strips laminated around the curved outline.

Ailerons are also simply slabs of foamboard with balsa around the edges. Later on I'll add some 1/32 ply to take the control horns.

20201017_081453.jpg

Bags of wing area,

Note leading edge cutout for fuselage.

I don't have any pictures of the fuselage under construction. The lower half is a very much conventional balsa sides + 1/32 doubler build.

I didn't buy any ply for formers - I dug out some B&Q cheap ply of around 5mm. It's not as heavy as proper birch ply and not as light as lite ply. The firewall is two pieces laminated together. At the front of the wing opening is a single thickness former to receive the wing dowel. All the other formers are foamboard or built up from some scrap balsa stripwood.

20201024_091224.jpg

I made the decking up as I went along. It's from two pieces of 3/32, again, leftovers, with a chunk of soft/med 1/4 making up the windscreen and front deck, just enough to make a nice round at the corner. All the decking formers are foamboard triangles (with the top chopped off).

The tailplane is all exactly like the ailerons - slabs of foamboard with balsa edges. Thin strips laminated around the board to make curved tips. All very quick and easy.

Not too much more woodwork left at this point.

Updates to come when I have something interesting to add!

Jonathan M27/10/2020 11:47:01
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870 forum posts
335 photos

Excellent mix-and-match creativity with available materials!

Re the foam-board, how can it be shaped to section (e.g. ailerons) and how does it compare in stiffness and density to medium/light balsa?

kc27/10/2020 11:49:20
6786 forum posts
174 photos

Can we expect a plan for RCME?

Nigel R27/10/2020 11:55:32
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4298 forum posts
716 photos

Jonathan, no shaping involved - these are just flat plates, I'm not tapering - that's far too advanced for this build! I was skeptical of the strength of this kind of structure but having used it on the Bigga Bit it seems plenty stiff. With the edging I would say comparable to a 3/16 sheet surface. A lot of that strength comes from the balsa edge; without it the foamboard is way too weak for something this size.

I guess worth remembering, a lot of fun fly just have 1/4 balsa framework and a good part of the strength of those type surfaces comes from the covering.

kc I have a rough plan drawn out of the wing and lower fuselage, so who knows, never say never smiley

Edited By Nigel R on 27/10/2020 12:05:20

Graham Davies 327/10/2020 12:09:17
156 forum posts
54 photos

Nigel, this is really good. I really appreciate 'scrap box engineering'; it's better than worrying about what we can't do, isn't it?

As you know, I'm exploring foam board, and I can see all sorts of possibilities. I like the idea of ribs as it is quite stiff in compression, and 5mm board would do away with the need for cap strips.

I think the gauntlet may have been firmly thrown down!

As long as I have enough stock for my promised (to me) 3/4 sized baronette, I may join you...

Graham

Nigel R27/10/2020 12:20:55
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4298 forum posts
716 photos

Thanks Graham, although somewhat bizarrely I started this before I knew of the balsa shortage!

In this instance the foamboard is perfect - the ribs are 12" long and you don't get many of those out of a 36" sheet of balsa...

I would use caps by preference as the edge of the board is a bit fragile - when it comes to covering with film I found the caps really pay off.

Nigel R27/10/2020 12:29:56
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4298 forum posts
716 photos

For reference my Bigga BIt build thread is here:

Bigga Bit

in which I took quite a few more pictures as I went, it shows the wing structure a better than this thread does.

Nigel R29/10/2020 15:37:42
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4298 forum posts
716 photos

Some photos of the gear install work on the fuselage, whilst it is still open on the underside and everything is easy to access.

The motor mount is recycled from something else, hence the two sets of holes. It was included with a 1.20FS I bought from the popular auction site. It is the first time I have used one of these T mounts, I have to say, they're very easy to set up. It is all M4 hardware (which came with the mount!) which matches up nicely with the lug holes in the 70FS I'm fitting.

As is visible, for throttle duties, I simply poked a length of bowden cable through the FW. I'm using one of those screw connectors on the throttle arm. First time I've used these and can't believe I haven't before - it made the motor install a piece of cake. Much, much easier than the rocker arm setup I used on my last four stroke install, and it takes less space compared to a soldered on M2 extension + ball link.

20201028_174824.jpg

The other end of that cable has to be waggled by something - a lonely old standard servo at the back of the wing saddle area, resting on several 1/2" wide strips of B&Q 5mm ply. The wing blocks are also (surprise) some small rectangles of B&Q 5mm ply laminated together to make a 10mm thick lump, tapped M5 for several nylon bolts.

20201028_174805.jpg

Seeing as there aren't any other servos inside the wing area... they must be at the back end:

20201028_174723.jpg

I made the "box" first, from some hard 1/8 balsa, with (yet more) 1/2" wide strips of B&Q ply glued underneath, to take the screws. The whole lot was then carefully sunk into the side. It looks neater than just plonking some ply on the outside of the fuselage and doesn't take very much longer to do, just cut a few strips of balsa, cut them to length, and glue it up.

The two servo holes needed a bit of careful planning to avoid clashing:

20201028_174741.jpg

but avoid clashing they do. There is also some extra lengths of longeron added around the openings to compensate for the big holes in the fuselage side. My no-expenses-spared foamboard formers are also clearly on show there. They were a time saving dodge, over my usual method of fitting balsa crosspieces.

Incidentally, the fuselage longerons were all cut from the same 1/8 sheet that the fuselage side was cut from, waste not want not.

I'm away from home (while we still can) for a few days now, then it is time to attack the undercarriage, the tailplane mounting, close up the fuselage underside, and then it will (practically) be ready for covering.

Dwain Dibley.29/10/2020 16:49:35
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1588 forum posts
1562 photos

Crackin' Stuff Nigel.

D.D.

Nigel R05/11/2020 11:19:19
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4298 forum posts
716 photos

Thanks DD smiley

Another week on and a few more jobs done, starting to get down to the little bits now.

Fitted torque rod supports for some 8g wire gear, added some wing saddle triplers, reinforced the wing dowel hole, plus added a bunch of triangular stock jammed in the corners around firewall and "F2":

20201103_213121.jpg

Made a tailskid and stitched it to a piece of ply:

20201103_213208.jpg

Nearly forgot - put a paper tube in the fuselage to make servo install easier:

20201103_213240.jpg

And these untidy lumps of soft 1/4 will hold the fin in place. A little carve and sand to indulge in:

20201104_224110.jpg

Not much to go now. Get the fin support blocks shaped, then time to fuelproof inside the tank bay and FW, and close up the fuselage underside. Last two things, need some cowl cheeks, and a basic belly pan. Then it is covering time - must check on my film supplies and see what I have left!

Nigel R13/11/2020 09:14:12
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4298 forum posts
716 photos

The belly pan done... another good use for foamboard - the thin side pieces were easy to squish around the airfoil, then I could neaten up the lower edge with the sanding block before the sheet went on.

20201112_221200.jpg

Tail end finished up and stuck on:

20201112_221151.jpg

And I stuck some cowl cheeks on to improve looks at the front end. I think they could do with a bit more of a curvy shape, they're a bit square as things stand:

20201112_221222.jpg

Total bench time, 45 hours.

Total weight so far, 2lb (as pictured including all five servos and the engine mount).

The Surpass 70 is a fair old lump - although they do run nice - and I think the finished product is looking like 4-3/4lb. This should give a wing loading of 14 oz/sqft, or the CWL for those that like it (I do) of 5.5, which is right down there in the slow and floaty end of things. Whilst this is not quite as light as a dedicated contest fun fly type she is more of a sport model than a contest thing.

Not many jobs left - fit a strake, sort out the RX switch, cover up a few whoopses with wood filler and then get her covered. Might even have it polished off in time for the end of lockdown!

Zflyer13/11/2020 11:10:11
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51 forum posts
7 photos

Have you considered using the Graupner foam board for skinning. I have used it on a delta and it works a treat as it is very flexible. Comes is a variety of thickness

Nigel R30/11/2020 09:08:29
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4298 forum posts
716 photos

Hi Zflyer - sorry didn't see you post earlier. I have not tried using foam board for skinning yet. I think it could be a good option especially on electrics.

Nigel R30/11/2020 09:19:07
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4298 forum posts
716 photos

The last two weeks have been taken up with a lot of small finishing jobs, filling and sanding, fuel proofing, hinging, reinforcing for control horns, that kind of thing, nothing big. But also, the main film covering event:

20201130_085648.jpg

20201130_085548.jpg

The orange is a bit more red in real life.

Underside is an orientation-friendly dark colour:

20201130_085626.jpg

Need to add a couple of white flashes to the top side to break up that orange. Plus some dark bits for a pretend canopy. Quite pleased with how it has come out given the simple & quick nature of the build.

My original plan was to use up covering in the scrapbox - some leftover yellow and the dark blue seen on wing underside. Problem was I didn't have enough blue to do the underneath. That meant the yellow wouldn't stretch to the whole airframe which mean I either had to buy more blue or more yellow. Then I couldn't find either colour again... so ended up buying a roll of orange, which turned out to be about a foot too short to cover the thing without buying a second... angry Hey ho. One tries.

Jobs left - trim scheme, refit all gear... and go fly... so probably another month left then! wink

Nigel R01/12/2020 15:55:23
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4298 forum posts
716 photos

Most gear in place.

All pushrods to make up, battery to stow, trim flashes to add.

20201201_143550.jpg

Graham Davies 301/12/2020 16:09:08
156 forum posts
54 photos

Fantastic Nigel, looks like you nailed the brief.

Of course, after 3 1/2 weeks of light winds, the start of which coincided with the start of lockdown 2.0, it's picking up nicely in time for the end!

Good luck with the maiden; I am sure it will fly really well.

Graham

Nigel R01/12/2020 16:18:42
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4298 forum posts
716 photos

Many thanks Graham smiley

I have no doubt it'll be 2021 before she leaves the ground!

john stones 101/12/2020 16:32:22
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11778 forum posts
1521 photos

Cracking job Nigel, looks like It'll fly up It's own backside, should be fun. Mini Jazzish.

Dwain Dibley.01/12/2020 17:04:49
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1588 forum posts
1562 photos

And it's my favourite colour Nigel, ................ apart from the blue bit. wink

D.D.

Stuart Quinn-Harvie 101/12/2020 18:26:10
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126 forum posts
88 photos

That's fantastic! Looks a bit like a Funfly Chilli Breeze

 

Great work Nigel.

Edited By Stuart Quinn-Harvie 1 on 01/12/2020 18:26:28

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