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Macchi M.39 Speedbird: radiators


DMC

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Recently, during a brief spurt of house cleaning, I happened across a journal that featured seaplanes and floatplanes.  On the cover there was a bright red profile of a Macchi Castoldi MC.72.  A featured article inside on the Schneider Trophy Cup piqued my interest on floatplanes somewhat and moa and greggle's builds on, respectively, the Supermarine and Curtiss entries ramped it up even further.  So, after researching the various entries, and being partial to those bright red Macchis, I started experimenting with the best way to build the floats for the M.39.  After several attempts and a couple of A4 styrene sheets I got a result that I was happy with.  I've since decided to build the other float and then continue on with scratch building the rest of the diminutive 1926 Trophy winner using the techniques found in Harry Woodman's book on scratch building in plastic card.

 

This first photo is of the completed float in 1:48 scale.  In successive photos I'll show how I went about plunge moulding the deck and keel and putting it all together.  Welcome to follow along and comments and suggestions always welcome.

 

Thanks for your interest,

 

Dennis

 

 

 

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I carved the full float, deck and keel, on my first attempt at getting a usable plunge for building an M.39 float.  The idea was to plunge mould the deck and then flip it over and plunge the keel.  The results were okay but the step was poorly defined and to fix it I would have had to separate the bow from the stern and splice in a piece of styrene. I decided to carve a new stern mould, plunge a new piece, and just butt that up against the step bulkhead.  Then I thought I'd just start from scratch and just went ahead and carved a new deck mould and a forward keel mould.  The new deck mould is the top one in the photo below.  I'll post photos of the keel moulds and plunge results probably tomorrow.

 

The second part of the photo shows the plunge result using the new deck mould.  Good enough to use in building the float in the introductory photo in #1.  

 

Thanks for your interest.

 

Dennis

 

 

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THIS I want to watch....!

Put in as much practical hints n tips on moulding process as you like.

I've got plans for the S5 and S6b and had them for decades, and the vague idea of scratch building has always lingered. But haven't got a cluee on how to go about it.

So this is going to be brilliant to watch.

 

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9 hours ago, Scimitar said:

I'll watch from the back row if I may?   'Scratchbuilt' caught my eye right away.

Certainly, still plenty of seats up front, however.

8 hours ago, rob Lyttle said:

THIS I want to watch....!

Put in as much practical hints n tips on moulding process as you like.

I've got plans for the S5 and S6b and had them for decades, and the vague idea of scratch building has always lingered. But haven't got a cluee on how to go about it.

So this is going to be brilliant to watch.

 

 

Hi Rob,

 

You might want to look here:

 

 

 

3 hours ago, Bandsaw Steve said:

I’m in on this one!

Watching and learning. 😃👌👍

 

Honoured, and welcome.

 

Thanks guys, something to live up to now.

 

Dennis

 

 

 

 

 

 

 

 

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Cool!

Actually I hope to see more IP racers in 1:48 the next years after MikroMir and Dora released/announced several the last months. Strangely the Macci M39 and M67 are quite neglected subjects so far.

 

Will watch with interest :popcorn:

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7 hours ago, cngaero said:

Sitting here nice and quietly.

Oh I do love a good scratch.

Yes indeed, so do I. 

 

6 hours ago, Caerbannog said:

Cool

Thank you.

 

4 hours ago, rob Lyttle said:

I was going to say Flag me when you "publish", but no need now....

I'm on the case!

👍

Thanks, Rob.  And, since you are a dab hand with a pencil, why not try a few sketches?  When you have time, that is.

 

1 hour ago, Courageous said:

Move along lads, gota watch this. :popcorn:

Just received my latest book purchase, 'Speedbirds', brilliant book of beautiful Schneider flyers (and others). :Tasty:

 

Stuart

Thinking about getting the book myself, Stuart.  B’day book token.

 

Dennis

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Top half of photo: plunge moulded deck shell in .060 styrene.  Using .060 was just an experiment, I used .040 for the completed float but the thicker shell would give me a little more margin for error.  

 

Bottom half:  A .040 shell trimmed and ready for the bulkheads and keel pieces to be attached.  Two ways to attach the keel pieces, just inside the float shell or butted up against the shell with a slight overhang to be trimmed off after the cement has set.  Note the stern extension.  The stern on most of these floats is quite fine and impossible to get by plunge moulding.  I trimmed a little off the stern and added the solid piece to be thinned down later.

 

Thanks for your interest. 

 

Dennis

 

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This, it's exciting!

Glad to see adventurous modelers!

A bit late now and you may know about it already, but there used to be an Aeroclub generic float vac sheet. Many times I used them, generally having to make some sort of adaptation, but it's useful to have one at hand.

I got mine of course second hand, but perhaps they pop on the usual places for "used" modeling items.

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Since you carved wood masters already, an alternate way to go is to use two pegged blanks that later are separated and vacuformed as longitudinal left and right halves, sort of like this (you know this, but perhaps this may be useful for other modelers).

Sorry about the amount of images, necessary to describe the process:

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I will observe from afar now.

Cheers

Edited by Moa
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17 hours ago, rob Lyttle said:

So, port and starboard floats are identical,

As far as I know, Rob.

 

Okay, strange things happening with the quotes. 

 

Thanks, Moa, I’ll just edit this a little.

 

Excellent, glad you find it so.  I gave splitting the floats vertically some thought but decided I didn't want to have to deal with the seam right on top of the float, although it didn't seem to give you any problems on your S-5 build.  When I get around (soon) to carving the fuselage moulds I will use that exact same method that you've described.  No pegs, however, just a spot of glue on a thin scrap of shaving to allow me to get a blade between the halves. 

 

Photos just fine, we like photos.

 

Mattel vacuum former quite a rare item.

 

Cheers,

 

Dennis

 

 

 

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I thought cementing the keel mould between the float deck sides was the way to go when assembling the pieces together.  Not much margin for error, however, and I've a slight gap that I'll have to deal with later.  For the aft half I cemented a wider keel piece to the float chine and then filed and sanded the overhang flush. Perfect, no seam to have to deal with.  

 

Thanks for your interest.

 

Dennis

 

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To get a wider keel piece, bow and stern, I glued a 1/16th piece of balsa to each side of the mould to give it a little extra width.  Also opened out the female mould to get the extra clearance needed.  First plunge using .040 styrene looks okay.

 

Thanks for your interest.

 

Dennis

 

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On 8/2/2018 at 10:15 PM, rob Lyttle said:

So, port and starboard floats are identical, and it's the leg attachments that are "sided"?

I think the floats and mountings are identical. The wings however are asymmetrical, the port being 4.7m and the starboard 4.56m (figures from the Pegram book - "Schneider Trophy Seaplanes and Flying Boats").

Watching with interest.

 

Dave

 

 

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52 minutes ago, Fastcat said:

I think the floats and mountings are identical. The wings however are asymmetrical, the port being 4.7m and the starboard 4.56m (figures from the Pegram book - "Schneider Trophy Seaplanes and Flying Boats").

Watching with interest.

 

Dave

 

 

Thanks for that, Dave.  I'll look out for that book.  Nothing I have mentions the asymmetrical wings.

.

I'll just take a moment and thank everyone for the "likes".

 

Okay, I expect the use of these clippers as modelling tools might raise an eyebrow or two gut I assure you they are used for nothing else.  They came in very handy when fitting the bulkheads to the floats.  Concave and convex with  optional gold plating.  Convex probably hard to find. 

 

Thanks for your interest.

 

Dennis

 

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Hi Dennis,

                  If you intend to do more Schneider Trophy subjects or just have an interest in the topic, the Pegram book's great as it includes good 1/72 drawings of all the main participants. It's also got insights into the design aspects and well researched descriptions of the development and race year by year. Wiki mentions the asymmetry but gives no figures whereas Pegram gives data for the span and sweep-back plus float length etc. It's not cheap but it's a good book and well worth it.

Good luck with the model.

 

Dave 

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11 hours ago, Fastcat said:

If you intend to do more Schneider Trophy subjects

Yes, apparently heading in that direction.  The 1/72 drawings would be worth having  Just set aside Derek N. James book on the races to type reply.

 

Dennis

 

2 hours ago, Bandsaw Steve said:

:party:Hey DMC! I see you have just hit 1000 likes. We want to see some pictures of the party! 🎉🎈🎊 

Nonsense, Steve, who counts such things.  Anyway, more like 100, maybe.

 

Dennis

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Floats done: a pair and a spare.

 

Fuselage next: balsa blocks tacked together with a sliver of balsa at either end leaving just enough gap to get a blade in.  After carving the halves will be separated and each half moulded.   Various lumps and bumps, headrest, etc., will be added after I get a useable fuselage shell.

 

Thanks for your interest.

 

Dennis

 

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7 hours ago, greggles.w said:

Terrific- just terrific

Wow! Thanks for that and it’s good to see you back.

 

Cheers 

 

Dennis

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