And now for something completely different

[Spitfire]

Having just finished my long term project - the 1/10th scale Spitfire now I'm going to try something a little different ...
Going back in time a little more to a Fokker Eindecker



Utilising my tried and trusted building style - my mate in Kidderminster - having built one 30 years ago for internal combustion has resurrected it from his loft and converted it to electric and now he's sending me Corel Draw files so I can make one too - but making good use of his 'updates' and 'upgrades' ..

Ailerons were not used back in the 1st WW then they used main plane wing warping - his model only had rudder and elevator but he's now designed a novel upgrade where the main wings are fully moving - not warping [which would be hard to do on a model] but moving like the elevators and canard wings on modern jets.

Not sure how it works yet - but we'll get to that - but for now here's the start ...

Ply rib template cut from the Corel File above ...



26 1/16th ribs cut from the template and 26 riblets + 4 ply strengthened innner ribs ...



Basic fuselage started ...



Ply strengthened formers added and engine mount ...



If I remember I'll add to this as I go - just started the wing this evening ...

[Dagger_id]

Great work!

[Spitfire]

First wing started ... now I've got to do it all again the other side

[Sooty655]

Ailerons were not used back in the 1st WW then they used main plane wing warping - his model only had rudder and elevator but he's now designed a novel upgrade where the main wings are fully moving - not warping [which would be hard to do on a model] but moving like the elevators and canard wings on modern jets.

I can understand how wing warping could be done on a biplane by pulling on the trailing edge of one plane from the central part of the chord of the other plane, but how was wing warping achieved on a monoplane?

[Spitfire]

Well you've seen that mast and all that rigging on an Eindecker - top and bottom of the fuselage and wing ...



Well here's why ...

https://www.youtube.com/watch?v=t7E909cJKgs

It's not smoke and mirrors - it's wires and pulleys

What we are going to do to simplify things is have the whole wing rigid - but have it pivoted around a 6mm carbon spare that means the wings will 'waggle' in opposition like one giant aileron each side - our rigging will be purely cosmetic

[Sooty655]

Thanks for the explanation, David.

With the acute angle of the wires, the whole system must be terribly inefficient. I dread to think what the stick forces on the original aircraft would have been.

[Spitfire]

Well I suppose if you think about it nearly every aeroplane flying at that time was, in some way, inefficient

I don't suppose the stick forces were too bad - what with the addition of pullies/levers and their assistance - and it brought a whole new meaning to 'fly by wire' ... nothing new in aviation eh

I would love to have been around at that time to see the 'innovations' happening almost daily

[Sooty655]

I don't suppose the stick forces were too bad - what with the addition of pullies/levers and their assistance - and it brought a whole new meaning to 'fly by wire' ... nothing new in aviation eh

"Fly-by-wire" -

The difficulty with using pulleys and levers to gain "mechanical advantage" is that you always have to trade force for distance, i.e. you amplify the applied force by increasing the input movement, which must have been difficult within the confines of the cockpit.

I wonder how much movement was actually required at the outer trailing edge.

[Spitfire]

I wonder how much movement was actually required at the outer trailing edge.

Your wish - my command ... full scale Eindecker .. wing warping demo

skip to 2:20 for the answer

[Spitfire]

Both wing skeletons complete



Now to the tail .. elevators and rudder

[Nickolas]

Gee whizz that is impressive. Oh the office chair needs re-skinning too while you are at it.

[Spitfire]

Gee whizz that is impressive. Oh the office chair needs re-skinning too while you are at it.

No No that chair is my best friend - there's no way I could spoil it by mending it - it's just 'comfortable' as it is

So - to the tail... elevators under way

[Dougs]

Awesome work

[Jigsaw]

This is brilliant

[Spitfire]

Thanks for the kind comments - it's no different to building model steam engines - but in wood not metal - and not so precise really either ... its just an absorbing hobby ...

So now the elevator / rudder assembly is pretty much complete - all I've got to do is attach it to the back end of the fuselage and then think about the control runs





One bit of fun I had with the tail assembly is that I can advise that carbon rod goes soft when heated - but hardens again when it cools The 2 elevators are joined with a carbon rod which passes through a brass tube - and that brass tube is connected to another at 90 degrees which the rudder rotates on - those 2 tubes had to be soldered together where they cross with a thin wire wrap - when I did the soldering the carbon rod joiner was inside the tube and I suddenly noticed the elevators could move independently The rod had gone soft with the heat - so I clamped the elevators together straight and prayed it would harden again when cool - and it did

Those capping strips top and bottom of each 1/8th rib were a real fiddle ... 3/16th by 1/8th and sanded front and back ... what a pain they were... but thankfully CA makes the job quicker and easier - years ago with balsa cement it would have been a nightmare

The controls will be closed loop for the rudder and elevator and the wing will be a whole wing 'waggle' type system where the wing is slotted on to a 3mm carbon rod and will be rotated up and down around that by 2 servos ... this is the sort of Corel Draw instruction sheet I get from my mate in Kidderminster by email - and these are the wing 'waggle' controls - or part of it ...



Those orange and yellow bits are the wing and elevator horns working around a central wire axle - now made and inserted ... ... all made from ply and balsa on a piano wire axle with a brass tube joiner between the elevator horns - fiddly to cut out and a beggar to install - but all done



Now starts the fun bit of installing the servos (the blue bits) and then connecting it all up ...some of that will have to be done after it's covered ... we'll come to covering later

The only real bit of major construction left is the motor cowl which is quite a beast - and it will also house the battery ... that'll be the last bit I'll do ..

So there we are for now.

[Spitfire]

So now the servos are in and the aileron 'waggle' and elevators are connected at the front end - I can't put the closed loop wires in to the rudder and back end elevators until the covering is done.



The motor is in - and I've had a trial run and it will swing an 11" prop nicely with plenty of power.


I wasn't looking forward to this bit but I've made the cowling ... it's like a jigsaw - 6mm balsa cross grain laminations and lite ply base plus a 0.8mm ply skin ... 10 parts in all ...




The diagram shows how the battery will have to sit on a shelf over the motor inside the cowl - it'll be a tight fit and involve attaching the cowl with keyhole slots and screws - not my favourite bit of alignment construction ...


Oh and the tail is attached ...



Onward ...

PS - Looking at those pictures now I am realising that I have just installed the biggest building worktop I have ever had in my workshop (10 ft x 3.5 ft) and I am STILL working in one square foot surrounded by building mess and detritus that I constantly have to move to get space. I must be just a messy builder - it seems you give me space and I'll fill it with c**p

[Spitfire]

Well - it transpires that my connections from servo to 'wing' waggling' mechanicals were flawed and there were too many variables with potential for 'slop'.

The angle of the servo arms to their bellcranks was also too sharp and because of that I bent the pushrod wires - this was a bad idea - and I added servo grub screw connectors to grip the pushrod wires which also added another complication that increased the already bad angles.

SO - although they were glued in - the servos had to be unceremoniously hacked out and then set further back and buried deeper in the side cheeks (of which later) - the grub screw connectors have been dispensed with and replaced with the tried and tested 'Z' bend and brass inserts from connector blocks to join the two wires and that gives all the adjustment potential I need.

Where the pushrods attach to the ply bellcranks there was also further 'slop' - so I drilled out the holes and glued in brass tube to suit and that's eliminated that problem.

The servo installation is now not very pretty following the 'hacking' out - but it now works much better and anyway no one can see it when its finished...

This is the 'wing waggling' (aileron replacement) mechanism in action...

http://vid300.photobucket.com/albums/nn21/DavidXH558/2014-12-10%2016.57.43_zpsu9m7ejvc.mp4

Side cheeks are now shaped and glued on and you can now see how the servo bodies - which stick out of the fuselage sides - are hidden within those ... you can also see evidence of surgery to the starboard ply side where I had drilled the hole for the 6mm carbon wing joiner rod 1mm too low ... I had to cut out a square of ply and replace it with new then re-drill it - now its fine.





So that's where we are at now ...



I think it may be covering next - then it'll be the closed loop elevator/Rudder connections - then loads of wire bending for the undercarriage and dummy wing bracing wires supports ....

Oh and also in that last pic you can see a photo of a dummy Spandau Maxim gun I've got to try and copy from scratch ...

All good fun ...

[Spitfire]

Main covering now finished .... I love solartex

I am well pleased with it ...







This last pic shows how the wings are threaded onto a 6mm carbon rod and 2 wire control horns then the band passes through the fuselage and hooks onto the 2 wire hooks and that's all that holds the wing in place - there's 2mm ply washers in there to hold the wings off the fuselage - they then pivot around the 6mm rod to give 'aileron' control.



Now for all the fiddly stuff - closed loops and the like

[Dougs]

wow David just, Wow!

[Spitfire]

Now we are moving on to the finishing touches, the functional control bits, the 'add ons' the 'fripperies' ...

I've coupled up all the closed loop rudder and elevator wires using 30lb fishing trace wire and 1.4mm crimps (useful stuff fishing equipment ) - all working fine ...

I mulled over the possibilities of a potential 3D printed Maxim/Spandau gun and finally decided to adapt a 'solid' one I bought earlier which (disappointingly) had a solid air cooling jacket and no barrel visible (obviously)..

So I cut the one I had into several bits and set about it with the flexible Dremel and a dentists tiny round burr I was given years ago - I then discovered that the barrel part was actually hollow so there wasn't much material to remove. However, the holes drilled left quite a flimsy structure and, as usual, things got messy and some of the structure broke off

This led to me having to put an 8mm drill through the end of the barrel unit and then make an 8mm aluminium rod on the lathe the same as the diameter I'd just drilled - I then lightly greased that before inserting it and then adding small quantities of P38 filler - when dry I redrew the frame hole matrix with a pencil on the filler - withdrew the aluminum rod and drilled out the filler to regain the hole matrix. I then soaked the filler bits in CA to add a bit of belt and braces strength.

Then I drilled the muzzle end and added a 3mm carbon rod as a barrel - which was obviously absent on the solid original - then rebuilt all the guns parts I'd previously sawn up and added some good old Humbrol Matt Black ...

So I ended up pretty much 'making' one from a 'kit of parts' .... Quite pleased with the result - you can't see the barrel in this shot - but there is one going from the muzzle to the breech inside the framework



I then painted the pilot bust I bought not being confident enough to carve my own .. he looks suitably sinister
I am currently filling in the 'hollow' goggle frames with small amount of mixed epoxy resin which looks remarkable like glass when dry





I then had to make the undercarriage frame - lots of wire measuring - bending - cursing - rebending - ruining - starting again etc etc - then soldering it all up using a jig I built to hold it all relatively straight (and even then its not perfect




Onward - I've now got to cover the front fuselage sides in 0.5mm plasticard which will eventually be sprayed 'aluminium' to match the cheeks and cowl which are also 'aluminium' ... they will also be covered with tissue and dope and sanded before spraying to give a uniform finish.
I have yet to work out how to use 'keyhole' shapes to attach the cowl as the battery will be inside the top of the cowl so it need to be removable yet secure - magnets (my usual battery hatch method) wont suffice in this instance

Then on to making what, on mine, will be a dummy framework of piano wire and more trace wire to make the wing 'braces' ...

Lots yet to do

[Ray C]

David.....What a great way to spend these cold winter days & nights....well done

[Spitfire]

David.....What a great way to spend these cold winter days & nights....well done

Only the nights I'm afraid - I'm still working full time during the day

But with the heater on full blast and the TV on as something in the background I sit in my workshop cosy warm and play at fettling models as much as I can

I've just been sitting out there for 2 hours trying to draw and transpose black iron cross markings onto the covering ... its MUCH harder than I thought

[Spitfire]

I've just been sitting out there for 2 hours trying to draw and transpose black iron cross markings onto the covering ... its MUCH harder than I thought

Does anyone have an experience of using a ruler pen filled with thinned paint



It's new to me and its the only way I am going to get the Iron Crosses painted onto the wing and fuselage covering accurately. I have to do the straight edges of the crosses with a freehand pen and a steel rule and the curves with a compass set with has a ruler pen attachment.

I am having a devils own job to get the paint the right viscosity and the gap at the end right - I know its all down to practice but has anyone got any hints or tips from ever having used one in, say, another hobby - I know calligraphers use them??

[Spitfire]

Well its pretty much finished ... just a few tinkering bits to do ...

Painting the iron crosses on was interesting - I've never used a ruling pen before and after messing about with paint viscosity and the ruling pen gap I finally got it to work ok - so with a compass and a measuring formula I managed to do the outlines of the crosses with a compass arc - then just filled in with black - I also used it to do the white boxes with a ruler.

I covered the front where the 'pretend' aluminium is with tissue and dope - then sanded it and sprayed it acrylic aluminium ...

I am not going to add the wing bracing wire structure until after I've flown it as on this model it'll only be 'decorative' - the anchorage points are all in - its just a question of adding it later - if I ever bother.

And look - you can see through the gun cooling jacket after I laboriously drilled it out











Well pleased with it - all I have to do now is get the courage to fly it.... on a calm day

[Ray C]

Superb job....Can we look forward to some pictures or a video of the event.