Fokker F.VIIa

[marcin_pl]

What is a thickness of the LE sheeting?

Marcin

[Stunthenk]

About 0,6 mm. I started with a 1 mm sheet that weighed 9 grams (standard size, 1 meter by 10 cm. so a density of 0,9). After applying the sheeting I did some more carefull sanding at the spar and the LE so now it is anybody's guess!

[OZPAF]

Nice work Stunthenk! Your use of bamboo is interesting.

John

[Stunthenk]

With a model like the F.VII construction goes along fine, untill you get to the dreaded exposed engine. Then all momentum disappears.... That's the reason why this update took a while. First you have to design your model engine. In this case the engine is a Bristol Jupiter VIIIF, a 9 cylinder single row radial engine with a front exhaust collector / silencer. According to my enlarged 3-view the diameter should be approx. 36 mm. I therefore decided the diameter of the crankcase to be 18 mm, leaving 9 mm for each cylinder assembly. Perhaps scalewise the crankcase should be smaller. But in the model it is also the noseblock so it needs to be sufficiently sized. The cylinders have a part with slightly larger cooling fins under the head. The cylinder head has exposed rocker arms and valves. Each cylinder has two exhaust ports, with a Y shaped pipe connecting to the exhaust collector. The collector has two exhaust pipes going to the rear of the motor.
In the first picture you see the noseblock / crankcase in he model, a test cylinder and 9 cylinder stubs on a stick board between two supporting sticks to be sanded down to the correct size. Nine thinner, larger diameter stubs are wainting their turn on the sticky board to be sanded; and 9 3 mm balsa oblongs are waiting to be turned into cylinder heads.
In the second picture you see 9 cylinders under construction, the exhaust collector and the test cylinder.

[dputt7]

Great to see this amount of detail. Good luck with the rest.

[TheLurker]

With a model like the F.VII construction goes along fine, untill you get to the dreaded exposed engine. Then all momentum disappears....

Aye.  You have my heartfelt sympathy.

However, I'm in complete agreement with Dave; the level of detail is very impressive.

[Stunthenk]

Thank you very much, kind gentlemen, but in my opinion this is simple balsa bashing and not comparable to the efforts of the real experts. Just look at pictures from Walsall and Wychen models and you know what I mean! And I still try to figure out how to do the Y shaped exhaust pipes? (And of course, I HAD to do an airplane flown BEFORE the introduction of NACA style cowlings....)

[TheLurker]

...still try to figure out how to do the Y shaped exhaust pipes?

Henk, if the exhaust stubs aren't too small to work with might something like the sketch below work?  Make the Y joint in basswood/bamboo and then paper tube extensions into the Townend ring and the cylinders.

[Stunthenk]

I've tried to make satisfactory cylinders with cylinderheads but I am simply not satisfied with the results. I will have to start over. But, in order not to stall the project, I've decided to postpone that. But that brings me straight into the next problem, the burnished metal aereas on the nose! Of course I've read with interest Lurk's experiments with fake silver leaf; and  I suggested using Bare Metal foil. Well, that was my starting point. I punched out 2 mm disks of 600 grit wet & dry paper and stuck that to a round balsa stick. No joy, the result was irregular scratches. So I stuck another disc to a piece of 2 mm dia, wire with a rounded point; not much better. Finally I remembered reading somewhere a long time ago that the eraser on the back of a pencil would work. And indeed, neat round burnishes. But 8 mm dia, much too big! Next step was a 2 mm slice of eraser held in a pin vice. Not bad! But when I cut the piece of foil from the backing and smoothed it on a piece of soft balsa, the marks became too indistinct. The Bare Metal foil was too soft! And trying to burnish the foil while on the balsa resulted in dents. Lurk's Ryan NYP report featured a finished model by Peter Smart where the burnishes were made with a silver marker pen on painted tissue. I took a 2 mm Molotow silver marker and applied that to the foil. Reasonable, but the Chrome ink looked darker than the foil; I had expected the oposite. Oh, well, exit the Bare Metal foil.
Next step was silver tissue. Mine is no modelling tissue, but came from a stationary store. It tears very easily along the grain so is useless for covering open areas, but the nose of the F.VII is sheeted. This tissue has a dull and a shiney side, and the Molotow dots on the dull side look promising. So that is what I am going to try.
But first I need to cover the fuselage. The structure visible through the side windows was painted red brown to match the F.VII in the Lelystad museum, rectangular window strips were cut from thin transparent plastic and applied using thinned UHU Hart. Then the aluminium strips separating the individual windows were drawn with a 1 mm Molotow chrome marker. The hard part was cutting the side pieces from blue and black tissue. The top and bottom of the fuselage were covered with blue tissue using Deluxe tissue paste. In the picture the top and bottom tissue is awaiting trimming after which the side piece can be applied.