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Fokker E.III Eindekker revamp


reg shaw
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Can't resist a challenge, especially in the shape of a WWI aeroplane!! It was built by a mate that has lost interest. Its flown a few times but has issues in that it burns servos out in the wing warp circuit. Its also a bit of a porker, don't know the auw but know the model flies well enough to be worth the extra effort of lightening, detailing, rerigging and re thinking the installation to get everything out of the way. After a 600 mile round trip, all in a day (I was keen!!) the monoplane found its way back to Staffordshire from the Lizard in Cornwall. It was assembled when I got back for a looksee to assess the work it needed.

Ian.

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Cheers folks. Its a 1/3 scale model, spans about 130" and about 100" long. Guesstimate of weight is approaching 40lb, Powered initially by a Zenoah 80 twin, but it'll be having a geared Zenoah 38 swinging a 32" x 18" prop. It will also spin a dummy rotary now as I've knocked the firewall out to move it backwards to get it all in. It had about 6lb of lead in the snout so a lightening exercise will be carried out in the back end department. From the brief look I had I've drawn up a list of things I want to do.

The fuselage has been gutted to put things back in in a way that is a, more practical b, tidier, c, leaving the cockpit devoid of everything that shouldn't be in a cockpit.

The wing warp system needs remaking as it is geometrically wrong and the reason for the burn't out servos (the last was a 35kg torque jobbie!!) The warp wires have an inner and outer closed loop, the inners move half of the outers since they are halfway between the outers and the root pivot. As they were, the servo was trying its best to bend the rear spar 's' shaped.

The rear spars need altering at the root so they pivot at the fuselage. The rear spar itself shouldn't need to be bent for warping, it simply pivots at the fuselage. They also might need separating from the ribs, depending on the rigidity of the wing panels. On the full size, the ribs free float on the rear spar, held in position by a block each side of the rib, these blocks are glued to the spars, not the rib itself.

All the rigging will be replaced with custom fittings, both for piece of mind and scale looks.

The basic airframe is great and gives an ideal base for a lovely model. I sometimes like refurbs more than new builds, its the hippy recycler in me!

The turret belongs to a 1/4 scale Vickers Wellington, more of which later when I get round to it!!

Ian.

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Here's a couple more pics. The fuselage structure is very scale like, using wooden dowel to simulate the steel tubing of the original. The rest of the airframe is pretty scale in structure too, just needs a bit of fettling. The model was built using some scale drawings I blew up to 1/3 scale, no alterations were made to the scale outline or sections, so the rudder and elevators are tiny in area! The wheels also need replacing as the tyres are way too thin and spoil the generally good look of the beast.

Ian.

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Well, remember that nice looking Eindekker, well its a bit like this.....

The main reason for getting it was to sort out the wing warping so that it was reliable and didn't need the power of at least 9 Shire horses to effect a turn. My initial thinking was the main problem was that both front and rear spars fit into sockets in the fuselage so any warping would have to bend the spars themselves which is not what happens in the full size. The rear spar pivots at the fuselage. So everything was removed to get to dismantle the rear socket in the fuselage, which didn't leave much left on! It was also noticed that the wings were very rigid, surprisingly considering its a single spar front and back. The size of spars in the wings is incredible, something like 35mm sq for the front and 30mm sq for the back!!! Even though the rear spar should pivot for warping, there has to be some TWIST capability of both spars since they are glued to the ribs between them and there certainly aint in this case. So, drastic action is called for. If new spars were fitted, the ribs wouldn't survive the surgery so a new pair of wings would be required, which wouldn't be beyond the realms, but then you may as well build another fuselage to suit!!!! It was decided to reduce the twist resistance of both spars by removing a goodly sized chunk from the middle, creating a top and bottom spar which will flex much easier. The slots were chain drilled 4mm initially, then opened out with gradually bigger drills. When I'm happy that enough is taken out, I'll tidy the slots up to finish, no point until then as the project is a failure if the warpery don't workery!

Ian.

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Cheers folks. Daunting amount perhaps, but it'll be worth it, if it works! The plan was always to recover for this season, changing from the colours of Ernst Udet to the even more dull colours of Max Immelmann, the most famous exponent of the Eindekker.. This recovering was to happen once the contraption worked right, so I'm now going a bit ar5e about face!!!

Ian.

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Hi Cymaz, the tailplane and rudder have already been lightened, there wasn't much that could be taken off as its all a bit minimalist anyhoo. The rear of the fuselage has had some attention too, but still could get a bit more in the form of removing the wooden crosses and replacing with cables like the rest. The tailplane mounting itself can have something done as its strong enough twice. This is because the wooden rear fuselage is strong enough and the steel framework strong in all the same places, so the steelwork is in for some dieting, I'll get some pics to show when I do it. The main weight saving behind the c of g will be in the form of getting rid of the unneccessary and moving forward the neccessary. The front belcranks for the tail controls will be upfront, in the shape of a rudder bar and joystick hopefully. We'll see when we get there. There is a lot to cram into that short nose so some of the servos might be under the pilots seat if space gets tight.

Ian.

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Hi Reg, very nice it is too. What a superb job. Perhaps you can give me some advice. I've got a 1/4 scale Proctor kit about half finished, and yes, its got wing warping. Does it really work, and what covering are you using? I'm thinking that it needs to be flexible enough to move

ernie

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Ernie, I'd follow the Proctor storybook to the letter, they are thoroughly tested and flight proven and extremely good quality creatures when finished!! Covering wise, I'd use Solartex, nylon or similar. The wings need to be very flexible in twist or you'll need serious servo power for operation. The flying and landing wires do all the work, with the warping circuit for control.

Ian.

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