Macchi M.39 Speedbird: radiators

[Courageous]

What Bandsaw says... very instructive.

What do you do with your old moulds?

 

Stuart

[DMC]

7 hours ago, Bandsaw Steve said:

52 minutes ago, Courageous said:

very instructive

Very instructive!

Thanks, Steve.

 

7 hours ago, Bandsaw Steve said:

brain-thinker brain-thinking.

Careful, all that cerebral cerebral  activity might cause a short circuit.

 

 

52 minutes ago, Courageous said:

very instructive

Thank you, Stuart

52 minutes ago, Courageous said:

What do you do with your old moulds?

I still have them, all the way back to the U-2.  I'd like to keep the M.39 ones as a set but if you'd like something to practice on I'll send you a couple of the easy ones as they are just in a box getting mouldy (groan).  If you get anywhere with the practice and want to try your hand at building a Speedbird M.39 then we'll see. Lots of practice involved and much wasted styrene, but plunge moulding can be very rewarding and help advance your modelling skills.   Also, I'll post a link for an economical source of styrene.   Good quality stuff and cheaper than Evergreen.

 

Thanks again guys.

 

Dennis

 

Edited August 30, 2018 by DMC

[Courageous]

Thanks Dennis, I'll keep it in mind...need to clear the decks of other subjects first. It will happen, just don't know when.

 

Stuart

[DMC]

Making a wing: this technique is right out of H Woodman's book, with only a minor change or two.  No doubt this technique has been demonstrated to better effect on BM before so apologies if you find this one lacking.

 

The M.39 wing is, according to my reference plans, a simple airfoil shape.  I sanded a 3mm thick length of balsa to a shape that looked right to me.  It is flat on the bottom and about 3mm smaller around  than the actual shape that the wing will be.  I used .015 styrene for the M.39 wing as there are no ribs showing.  If the ribs were to be scored into the styrene then .010 would be better.  The wing shape and the core shape are marked out on a rectangle of styrene large enough to be doubled back on itself. The trailing edge is lined up and taped together.  The styrene is clamped between two pieces of balsa and a heat source is applied to the leading edge, which is just flush with the balsa.  I used a hair dryer, and an oven glove,  and gradually pinched the balsa together as the styrene warmed up.

 

(Continued in another post in a few minutes.)

 

Dennis 

 

 

 

 

 

 

[DMC]

cont.

 

A liberal application of liquid cement is brushed onto the balsa core and let dried.  It seems this step is necessary to harden the balsa.  Double sided tape, boob tape my wife calls it, is applied to the lower inside surface of the styrene and the core is placed in position close to the fold.  Another length of tape is applied to the top of the balsa core.  the styrene is folded over the core and cement applied to the trailing edge.  The same balsa strips can be clamped on the tailing edge and the assembly left to cure overnight. 

 

The top right photo shows the core removed from the styrene envelope and the tape still stuck in place.  I removed the core because my first attempt at cementing the rounded wingtip together failed dismally.  I ended up cutting the wingtip off squarely and cementing a solid tip on and shaping it to fit (which I should have done in the first place)  Also, I should have used a slightly thicker piece as there is a slight depression.  Easily remedied, however.

 

Had the wing not had a slight sweep back, not much, only three degrees or so, I might have tried to do it in one piece.  

 

Woodman takes about three pages to describe the technique but it's quiet easily done after you get set up.

 

Thanks for your interest.

 

Dennis

 

 

 

[Courageous]

I have recently purchased H Woodman's book and it's really informative and also handy seeing someone else using his technique. As you say, the wing tips are a bit awkward. How did you mate the tip to the wing that is only a skin with no gluing surface?

 

Stuart

 

[DMC]

11 minutes ago, Courageous said:

I have recently purchased H Woodman's book and it's really informative and also handy seeing someone else using his technique. As you say, the wing tips are a bit awkward. How did you mate the tip to the wing that is only a skin with no gluing surface?

 

Stuart

 

Good for you, Stuart, it’s a little gem isn’t it.  I gave the blunt tip of the wing a good application of cement and butted a piece of .020 styrene against it and let it cure overnight.  The tip was two pieces of .060 cemented together. I did most of the tip shaping   before I cemented to the wing.  I also let the tip and wing join cure overnight before shaping the .020 insert and tip to match he airfoil shape of the wing.  The upper and lower skin combined total .030 and after hardening the balsa with cement the styrene will actually stick to it.  I had no problems with separation after the cement had fully cured.  Hope this helps.

 

Cheers

 

Dennis

 

 

[rob Lyttle]

Fascinating stuff.

And this sounds like a brilliant book by a "Leader of Modellers".

 

Let me ask this....

Could you clone a wing, top and bottom, if you already have a wing with a kit?

I'm asking because I have a WW1 German Albatros complete with lozenge pattern decal sheet. But I sometimes think solid plastic wings look too  "dense".

There should be light kind of showing through the fabric.

So it was a bit of a thought experiment really.

If the wings are cloned in thin sheet and assembled, maybe with some spars or a frame,  some light could get through and create this effect.

Then I see what you're up to....

Anyway, it's all in my head. I haven't done a biplane for several years, and I've not copied a wing, so it's all a bit Lala land!

Funny the things that get thought about 😁

[DMC]

Hi Rob,

 

Well, you could certainly duplicate a wing using similar methods, camber and all.  The transparency issue might be difficult to achieve, however.  Ten thousands would be as thin as you can ideally go, and it’s fairly transparent, and after you’ve scored the styrene, inside, perhaps you could darken the scored ‘ribs’ and they might show through if the wing was sprayed with a light linen colour.  However, you’d still need the balsa core and any decals would negate the transparency effect.  Might work on an earlier biplane before they started tarting them up with those garish colours and camouflage.  

 

Cheers

 

Dennis

[rob Lyttle]

OK, check all that. Thanks Dennis.

Ribs and structure--- both the appearance of the real structure and something to hold the model pieces together.

 

They were a bit psychedelic, weren't they?

If you combine that with the splinter camo patterns on the ships, the whole thing was a riot of abstract art!

[DMC]

 

Assembling the port wing:  pre shaped tip, .020 shim and squared off wing tip.  The tip has a tab which will be trimmed off and all three pieces cemented together.  After the wing halves are cemented together, they'll have to fit in a cut-out in the fuselage underside.  To get a rough approximation of what I'll need to cut out I shaved a pencil flat on one side and, following the wing contour, marked the fuselage.  

 

Still not sure how to deal with the wing radiators, etc.  Seller in China (!) listed this thin brass sheet on eBay so I bought a length.  I expected it to take about a month to get here but it only took about two weeks.  Very surprised.  Price was only £1.75 which included postage.  How do they do that?  Can't have made much off of my purchase.  At first I thought it was mylar film or similar but it is indeed brass and very thin.  Paper thin in fact.  Anyway, not sure how I'm going to use it but I've a couple of things in mind.

 

Thanks for your interest.

 

Dennis

 

[DMC]

 

Wing halves together with a slight sweep.  I didn't consider the damage I might do to the formers by cutting out the fuselage to accept the wing.  Only lost a little but retained the stick so no real harm done.  I'll remember that when I get around to doing the M.67.  I'll need a fillet for the wing fuselage join but the fit is pretty good so might get away with using a little Squadron white, or try Woodman's method.  Prop and spinner turned out ok.  The spinner is made up of four pieces:  the base plate, point and a piece on either side of the prop trimmed to fit tightly against it.  

 

I've only cut out the opening for the exhausts on one side.  A bit nerve racking expecting to mess things up.  I'll have a go at the other side tomorrow.

 

Thanks for your interest.

 

Dennis

 

 

 

[Fastcat]

This is looking really great. Coming together nicely.

Keep at it!

 

Dave

[DMC]

12 hours ago, Fastcat said:

This is looking really great. Coming together nicely.

Keep at it!

 

Dave

 

Thanks, Dave, hard at it.  Well, reasonably so anyway.

 

Cheers

 

Dennis

 

[Bandsaw Steve]

Very tidy looking work. 👍

[DMC]

10 hours ago, Bandsaw Steve said:

Very tidy looking work. 👍

Many thanks, Steve 

 

Dennis

[huvut76g7gbbui7]

I am really enjoying this thread.

Your explanations are very instructive and interesting and the model is really taking shape.

Thank You.

[DMC]

13 hours ago, Scimitar said:

I am really enjoying this thread.

Your explanations are very instructive and interesting and the model is really taking shape.

Thank You.

 

Pleased to hear it. And thank you, Scimitar.

 

Dennis

 

[DMC]

 

The radiators on most of the later Schneider racers were always going to be a problem.  The brass foil (#86) that I thought might be the answer to the problem turned out not to be so.  On the mock-up below it was impossible to get the kinks and creases out no matter how much I worked at it and it is much too shiny.  The 'rad' on the left is a fold of .010 scored styrene sprayed with Vallejo Old Gold and a touch of green just to give it some body.  Clearly, the styrene is the way to go and I'll get some proper brass paint to spray them with when that time comes.  Also learned that a grey primer is not the way to go under a red, Vallejo Scarlet, top coat.  White primer or maybe even Tamiya 'pink'.  

 

To match up the holes on the right side, under the exhaust cut-out, with those on the left  I used a simple jig lightly cemented to the fuselage and drilled them out using my trusty Tamiya drill.  I then used a welder's tip cleaner to enlarge them a bit.  Tip cleaners are quite useful, they come in sets of 8 or so and are very inexpensive. 

 

The diminutive Sopwith Tabloid, winner of the 1914 trophy in Monaco, has caught my eye and I have begun work on getting the top wing made.  The lower photo shows the set-up for scoring the ribs as described in H Woodman's book.  The 1/32 balsa core and then the wing and ribs drawn on .010 styrene.  A drafting pen, wedged and taped to prevent spreading, is used to score a double line in the styrene.  Done carefully, this technique will produce a pretty good representation of ribbed and linen covered wing.  Not new to many out there but I though repeating it could do no harm.

 

Next up: Woodman's wing fillet technique.

 

Thanks for your interest.

 

Dennis

 

 

 

[DMC]

 

Wing fillets or fairings:  I suppose I could have used a little filler for the fillets but I try to avoid filler whenever possible and I wanted to experiment with Woodman's method a bit.  First I carved male and female moulds out of balsa.  The shape is a sort of double airfoil so both sides are done with one plunge.  Starting with the first one, to the right, the plunge was too deep.  I added shims to the stop a couple of times until I got the depth I felt was correct.  I changed from .020 to .030 because the plunge thinned the .020 to around .010 or less.  Much too thin.

 

The two in the bottom left are about right and after sanding the end off I marked a line with the flattened pencil where I estimated I would need to do some additional trimming.   Bottom right is a temporary fillet/fairing tacked in place.  The fit is ok but it is only about .005 thick and that is much too thin.  Might also be a little too wide but good photos of the fillet are hard to find so I'm guessing.

 

Bottom photo:  with the plunged end filed off it's easy to get the ' wing shaped' sander in the opening.  Bought a couple of Vallejo paints this morning.  Ferrari red should do for the overall red colour and the brass might do for the radiators.  I'm thinking that decals might also do for the radiators.  A clear carrier with thin black lines for the openings or grooves over a brass coloured base.  Custom etched ones would be much too expensive.  Pondering that as a way to go.  

 

Also, a good link for anyone interested in Harry Woodman’s methods and techniques.

 

https://web.archive.org/web/20080122044909/http://www.wwimodeler.com:80/harry/woodman.html

 

Thanks for your interest.

 

Dennis

 

 

[Bandsaw Steve]

Excellent- as always! 👍

[Courageous]

Excellent work Dennis 

 

Stuart

[DMC]

13 hours ago, Bandsaw Steve said:

Excellent- as always! 👍

 

12 hours ago, Courageous said:

Excellent work Dennis 

 

Stuart

Thanks guys, very much appreciated.

 

Dennis 

[greggles.w]

A most ingenious approach to the wing fillets, and quite clean.  As it happens I’ve just emerged from several days cycle of wing fillet finishing on my Crusader ... filling & sanding & filling, again & again, with Mr Surfacer 500 ... all very fiddly working in the junction of fuselage & wing. Your innovative method looks like a wise alternative!

 

Your sculpting of this machine is most convincing, well done.

[DMC]

Ah ha, @greggles.w, your back!  I’ve been looking for you to show up.  I’m almost ready to start on the struts and would like a gander at how you set those jigs up.  

 

Thank you for the kind comments, and the plethora of likes.  And thank Mr Woodman for the fillet technique.  His book is reprinted in full in the link on #95.  Worth a look.

 

Cheers

 

Dennis