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Old Mar 12, 2004, 01:09 PM
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Peter Rake Sopwith Tripehound - build thread

(This thread was originally started on another forum a couple of months ago. Shortly after completing the wings I had to shelve the project to allow the Ryan Corsair to take precedence. Now that work has restarted on the Tripe I thought I'd copy'n'paste the earlier progress here!)

That Rake bloke has been at it again, I'm afraid........

As soon as I saw the article and free plan in the Nov 2003 issue of Flying Scale Models I knew I was doomed to build his 45" Sopwith Triplane. The article is based on two prototypes (one in the US by Robert Hoffman, and one in Australia by Rod Perrin).

A quick search on the RC Groups forum revealed a massive 460-post thread detailing the builds of both models;

http://www.rcgroups.com/forums/show...opwith+triplane

This is probably the most complex model that I will have tackled so far, so if I start to lose my way then please chime in and help!

Although designed for a geared S600 motor, I happen to have an AXI 2820/10 + ESC, and a 10xCP1700 cellpack sitting idle. That's over 300 watts looking for a home.....

Four mini-servos and a GWS rx also volunteered their services.
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Old Mar 12, 2004, 01:11 PM
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Telford, UK
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Just to complicate things a bit, I'm going to have to convert this one-piece model into having removable wings. I just haven't the space to store and transport this winged block of flats all in one lump.

Peter and I discussed this a bit a few weeks ago. I really want to avoid the traditional sport of spending 20 mins trying to rig a multi-winged model at the field; attaching each wing panel, miles of rigging and turnbuckles, lost screws etc. So, in similar fashion to my little BE2c I want each 'hand' of wing panels to come off as one unit.

Here's a pic of the BE so you can see what I'm blithering about.....
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Old Mar 12, 2004, 01:14 PM
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Reading through that massive thread on the E Zone highlighted a problem that caused Robert and Rod some head-scratching; that short little nose made balancing the Tripe very awkward. As I recall both pilots ended up fitting some of the battery cells within the cowl.

Now it seems to make sense to make the best of this situation, and start out with the cells in the cowl! More than that, let's make a feature of them by arranging them in a radial fashion and disguising them as engine cylinders!

A quick check on the plan shows this to be very possible indeed. If (against all odds) the model now turns out to be nose-heavy, then the rudder and elevator servos can find their way to the rear of the fuselage (still using scale exits for the closed-loop connections).

That's it for now.

The next job is to summon up the courage to go and cut out all those wing ribs. All 63 of them.
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Old Mar 12, 2004, 01:16 PM
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I cut a rib template from thin ali sheet with an an old pair of scissors, and stuck a wooden stiffener/handle to it. Then it was just a matter of holding it down onto the wood and drawing a knife around it.

Once I got started each rib took less than a minute to do. I've cut little nicks for the spar locations too.
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Old Mar 12, 2004, 01:17 PM
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Being frugal here - after all, balsa doesn't grow on trees you know...
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Old Mar 12, 2004, 01:19 PM
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With 6 wings, there's no point in rushing this model; rather it's a case of plodding on steadily.

Having cut the ribs, it seemed a good idea to make the tip plates and spars as a job lot.
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Old Mar 12, 2004, 01:20 PM
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I won't bore everyone to tears with a blow-by-blow description of the wing construction, but here're the upper wings.

With the spars, LE and TE laid down, I fitted the tips and a couple of ribs to hold it all in place. Having got it all in place, the aileron cutouts could be framed.

Thinking ahead a bit; I know the design calls for 2 links between the three ailerons, but I'm wondering if it would be possible to use a single link between top and bottom aileron, passing through the middle aileron (but connected to it by a spur). Hmmmmm....
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Old Mar 12, 2004, 01:22 PM
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I made the centre section this morning. Luckily, I've made the cf dowels long enough to determine the dihedral angle. The short lengths of ali tube are merely to space the dowels away from the spar a little, so that they should correspond with the tubes in the wing panels.
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Old Mar 12, 2004, 01:23 PM
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I finished off the upper wings, and tidied up the joining mechanism a bit. If you look at the wing that's partially detached, you'll see that the root rib looks pretty flawless. This is a total con - what you can see is simply a 1/32 balsa facing, installed to hide the ends of the spars.

The root ribs themselves were not fitted until the wing panel was fitted to the centresection, and so could be butted up nice and tight to the centre section.
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Old Mar 12, 2004, 01:25 PM
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I also managed to frame up the middle wing panels too!

As the panels are going to plug onto the cs struts, I'm going make the root ribs from 2mm Liteply instead of balsa, and then I'll sheet the tops of the inner bays in 1/64 ply.

Once again, the root ribs will be added with the panels jacked up to the correct dihedral angle, ie., with the tips resting on a 8x1050 KAN pack........
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Old Mar 12, 2004, 01:26 PM
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..........like this!

Once the ribs are dry I'll reinforce this area with some balsa block, to tie the ribs to the spars more securely.
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Old Mar 12, 2004, 01:29 PM
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And today's question is;

Who would be stupid to make the bottom wings and forget all about drilling the ribs to allow the servo wire to pass through?

I'll give you a clue - he's stupid and lives in Telford!

One of those 'Duh' moments I'm afraid. Never mind, a section of old tranny aerial (sharpened on the inside with a knife), made a pretty good boring tool to get through the ribs. As each rib was passed, a piece of piano wire was stuffed up the back of the tube to knock out the slug of balsa. After the tube was withdrawn I let a little CA soak in around the holes, so the ribs shouldn't be weakened too much.

Best of all.......


I'VE FINISHED THE WINGS!!!!!!!
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Old Mar 12, 2004, 01:30 PM
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I figured I deserved a bit of a break before starting on the fuselage, so I've framed up the tailplane. I would have done the fin & rudder as well, but it's on the other side of the plan!

Once again I'm using carbon fibre for the elevator joiner - this time it's the same 4mm tube that I used for the wing dowels.
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Old Mar 12, 2004, 01:32 PM
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Just to get the adrenaline racing, here's a view of the fin and rudder. Hey ho.......
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Old Mar 12, 2004, 01:35 PM
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All the above pics were taken over a 2-week period in January, so please don't think I've done all that in one day!

I've started the fuselage, and I'll post a pic or two when something recognisable emerges.........

tim
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