1/24 scale DH Mosquito for rubber power.

[Prosper]

After getting nothing done yesterday, this morning I decided to forget the nacelle rear fairings - sick of it - and start on the pendulum ailerons.

I have an oak block - once a sanding block - into which numerous small holes of different diameters are drilled. A 0.5mm piano wire pin is stuck into a suitable hole, and a long piece of 0.4mm wire has its end bent over. This bent end is inserted into another hole, and is taped down with masking tape. The long piece of wire can then be wound around the pin, as many turns as needed; released; ends clipped and turned up, and there you have yer bellcrank. Another one is wound the opposite way, for the other wing. The one pictured was wound clockwise, for the stbd wing.

Four more of these coils are made - this time of 0.34mm wire wound round 0.4mm pin, and with one end cropped off right at the coil, and filed smooth, so that there's just a coil with wire sticking out at one end. Two clockwise and two anti.

[Prosper]

Since the cranks were wound round a 0.5mm pin, that's the diameter used for the pivot pins*. A pin is seen fixed firmly into a hard piece of 1.6mm balsa - this will be mounted to the relevant wingrib.

The pushrods, extending out from the pendulum in the fuselage, to the long arm of the cranks, are of stiff 0.8mm balsa - a broad vertical bar and a thinner strip glued to it to make a T-section. The edges painted with yellow Sharpie pen are the edges to be glued: I found by happenstance once that yellow Sharpie ink goes bright red when CA'd. This can be used as an indicator of successful CA bonding.

This installation needs four bearings for which I use thin aluminium - from one of those disposable food trays - in this case snipped and chopped rounghly circular. A 0.5mm hole is 'twizzled' through it, then it's punched into a cup made in a thick slab of plastic card, to make a dome. The dome is lightly CA'd to the base of the pivot pin.

I got some more done than this but will post pix tomorrow.

* I don't know the correct or formal names for all of these things so kind of make 'em up.

Stephen.

[Mr Speedy]

Amazingly neat work!! Well out of my league!!👍

[Prosper]

Ta Mr Speedy

I reluctantly had to take up the nacelle rear fairing of the stbd wing. Oh boy. Another day wasted, with moulded sheet after moulded sheet provong inadequate. Today I reverted to a fix I'd been resisting all along - simply carving the shape out of soft block balsa. Only it's not simple. I'm creeping towards a result. The reason I disliked this way of doing things is the weight. My hunch is that it will weigh at least twice the sheet version.

The reason I could no longer ignore this fairing is that I made a pair of ailerons - but couldn't finish them until the wingtips are in place and finished. Can't do that until the many spanwise strips (pseudospars?) are in place. Can't do that until the nacelle fairing and pendulum setup is in place . . .

When I say 'can't', I mean 'shouldn't', really. Once those strips are in place working on the wing becomes much more awkward.

More soon I hope.

Stephen.

[Prosper]

I meant to add these pics when I last posted, but didnt have time. The first shows the link or hinge between the pendulum bar extending from the fuselage along the wing, and the bellcrank. By using  wire coils wound in opposite directions for opposite wings, I find that the coiled wire rides on the bent wire of the crank - a simple and v. low-friction result.

Next is a closeup of another coiled wire and some thin al. from a baking tray. This al. is folded around the wire and crimped, and a hole is made thru the end. This then becomes the link between crank and aileron. The point is that the coiled-end wire can be slid in or out of the folded al. tab. This is useful because of the huge leverage at this end of the pendulum system. Whereas the pendulum might swing several centimetres either side of vertical, at the aileron end, a millimetre of movement of the link seen here will rotate the aileron considerably. The ability to slide the coiled wire in or out of the tab changes the link's length, which allows fine-tuning of the aileron's neutral (pendulum centred) position. When done, a drop of CA run into the al. tab will lock the wire. Thereafter, flight trimming of the ailerons will come from adjusting the system at the pendulum itself.

This is probably clear just the same as mud is clear . . . I hope to take some photos that explain things better.

[Prosper]

Now back to the present. A picture showing the shaping of soft block rear nacelle fairing. The picture utterly fails to convey the exasperating nature of this job. I could make a whole new %***££ nacelle in the time it's taken to do this %**&& fairing. And it's not finished yet. Below the wing are two of the many failed moulded-sheet attempts.

Incidentally, the join between the removeable nacelle and fixed rear fairing copies a panel line on the ackshual Mosquito.

Finally, I meant to take a 'before and after' photo of the ailerons but this job advanced so smartly that I overshot, so one aileron is not fully 'before'. But then the other isn't fully 'after', come to that.

Stephen.

[Prosper]

Yesterday I finished the stupid rear nacelle fairing. It transpired that I could thin the block balsa more than I'd anticipated. I thought that the very curvy shape, cutting across the grain of the blockwood, would make the part brittle and ready to snap. In fact not. It's still heavier than the moulded sheetwood though.

Clear of that ghastly trap, I've been able to get on with the pendulum system today. To mount an aileron, the wingtip needs to be finished - but I'm not ready for that yet. So I've temporarily glued a strip of scrap wood with a hole drilled in it, to the wing. The outer aileron hingepin can slip into that. There's a picture of the inboard part of the stbd aileron with piano wire hingepin, and also the wire hook which the crank-to-aileron link hooks onto.

Stop.

I do have a problem with nomenclature here. I'm okay with 'pendulum' and 'aileron': it's the bits in between, that join the pendulum and aileron, that I have trouble with. F'rinstance, the bar running along the wing from the pendulum to the 'bellcrank': I want to call that a pushrod . . . except that it's a pullrod too. The bellcrank isn't bell-shaped and it doesn't ring. Anyway, here's a clearer picture of the 'pushy-inny-outy coiled-end thing'. This component proved too long, and I've pushed the wire further into the crimped aluminium, to the length seen here.

[Prosper]

A picture of the bellcrank pivot pin, lightly fixed to a wingrib. Now I've had the setup working, the position of this item seems good so I'll fix it well with CA.

The next picture is of that same part of the wing seen from underneath. It's hard to see what's going on, I admit. First, the aileron has to be removeable. Just in case. A slim plastic card rectangle with a hole in it is slipped onto the inboard aileron hingepin. The outboard aileron hingepin is slid into a hole at the wingtip, and then the plastic rectangle is spushed into the slot. The plastic rectangle projects out a long way for convenience: once the setup is tested and passed, I'll cut off the projection to a minimum.

Then a picture of the whole setup from above. With the crank neutral, the aileron's neutral. At this first fitting and testing stage there's still work to do - some bushings and washers, and endcaps.

Stephen.

[OZPAF]

That's a nifty hinge arrangement Stephen - light and practical.

As for a name for the pendulum transfer beam - how about "crank arm".

John

[Prosper]

Thanks John! Crank Arm it is.

As well as working on the right wing pendulum aileron assembly, today I made a spring catch for the right nacelle.

This little catch relies on the springiness of two 0.5mm lengths of piano wire. The wires are mounted strongly behind the mainspar; they take a sharp 90° turn, go through the spar at the top, and extend forward, ending in the pawl or whatever it's called - the wedgy thing that makes the catch. Inside the nacelle at the top, I glued a balsa ramp (arrowed). This takes advantage of the laminated former making a natural strongpoint. When the nacelle is pushed into place under the wing, the pawl rides down the ramp under spring pressure, and clicks up when it travels past the ramp. This is pretty neat given that it's an afterthought. To release it I can stick a fingertip into the nacelle from the front, but intend to make a small hole in the top of the cowling, through which I can use a prodder to push the pawl down.

The last photo is rather indistinct, but shows the catch in place, doin' it's job.

Stephen.

[bcarter1234]

Stephen,

I immediately thought of you and smiled this morning as I read this sentence in an article accompanying G.E Whitehead's 24" Nieuport 11 plans from the December 1972 issue of Aeromodeller.

"The sweepback of the wings combined with the small amount of (non-scale) dihedral provides plenty of stability without without recourse to such 'artificial aids' as pendulum control."

The cheek! What utter blasphemy, tacitly endorsing non-scale dihedral as canonical while condemning pendulum ailerons as artificial aids in the same sentence. Heretic! ;-)   

Keep fighting the good fight.

[Prosper]

. . .tacitly endorsing non-scale dihedral as canonical while condemning pendulum ailerons as artificial aids in the same sentence.

Har har

Yes orthodoxies can be very puzzling, in whatever facet of life. Artificial? Last time I looked, aeroplanes had ailerons which move up and down l. Most scale free flight model aeroplanes don't - isn't that more artificial than having them? My pendulum systems are made of balsa and bent wire - why would this be artificial as applied to ailerons, but apparently acceptable in all other areas of modelling?

Anyway, I must stop before I go into a rant and nurse forces me to take another of her 'little tablets'. Mind you, I'm tempted to make a basic Nieuport 11 with scale dihedral - it looks the same as a Camel dihedral-wise, and the lesser dihedral stability of the lower, dihedralled, wings of the Nieuport (because of their smaller area) might be well compensated by the sweepback. The Camel is very stable.

First, I must correct my last post - I said my nacelle latch was installed on the right wing whereas the photo clearly shows it's the left. I get muddled.

Photos show the pendulum components fully installed in the - uuh left? right? Left wing. Just about visible are the little plastic card endcaps on the pivots. With this done I could fit the 1,459 thin balsa spanwise strips (we-ell, five on top, three on the bottom in fact). In fact the whole, conjoined arrangement of crank arm, crank and aileron linkage can be smuggled into the wing after the cage of mini-spars is fitted. I did this on the test model. But it's a murderous job.

Note how the mini-spars wave somewhat from rib to rib - that's from my inaccuracy in cutting the slots in each rib. The 0.4mm balsa strips are pushed into a slot in a rib by pinching the strip either side of the rib and gently coaxing the strip into place - finished by tamping it down with some square-ended object.

Now I can get the other wing to the same stage and fix the wingtips.

Stephen.

[bcarter1234]

Stephen,

If you do a Nieuport 11 I'll be tuned in. There is just something I love about that airplane.

Your work looks wonderful as always.

[Prosper]

If you do a Nieuport 11 . . .

But when I think of it, I've got so many models to attend to - 3 or 4 unfinished projects and a couple of finished-but-untrimmed models, and a couple of experimental bulds i want to tackle . . . Aaiiiy - not enough time!

The wingtips. I trimmed the prawn cracker-style wingtip halves. Note how thin the wood is at the very tip (arrowed). The other arrow in the picture: see the billet of timber forming the leading edge - see how the leading edge continues a straight line well past the last rib. However, in front elevation the taper does begin from the last rib outboard.

Well, at some point I noticed that the billet of timber wasn't sanded very fair, and blithely gave it a few sweeps with a fine-grade sanding block. Then I glued the bottom skin in place. I saw that there was a slight gap between timber billet and skin, but cheerfully went ahead and stuck it down anyway. Then I went to peruse photos to see the position of the wingtip navlite transparency, and got an uneasy feeling. Back with the model I could see that I'd sanded away the correct wingtip curve. Hence the gap between billet and skin. It's much too rounded.

Great steaming idiot. I now have to remedy matters (time and faff) - I haven't decided how yet.

Stephen.

[Prosper]

{quote]I now have to remedy matters (time and faff) [/quote]  I made the other wingtip for practice, then repaired the faulty one with an almighty bodge, as ugly as they come. But it's under the skin, so who knows? I certainly don't .

There's quite a bit still to do on the wings/nacelles, but now I'm turning to the tail surfaces.

Stephen.