'El Sonora' Glenn Martin Flyer, 1913, scratch-build in 1/72

[Old Man]

This is the subject of the build:

 

 

 

This aeroplane, under the grand title 'Air Fleet of the Northwest' provided important support to the faction of the Constitutionalists led by by Alvero Obregon during 1913 and 1914. The aeroplane, along with the services of a professional pilot and mechanic, was acquired from the Glenn Martin Co. in California for $5,000, and smuggled across the border with Arizona in circumstances attended with a more than usual ration of skullduggery.

 

I freely acknowledge that a good deal of what I am doing in this build is conjectural, as there are no drawings available, nor have I even seen stated dimensions for this particular aeroplane. There is a decent photographic record of the machine, though, and Mr. Martin's designs at this time were largely copies of Curtiss aeroplanes, albeit tweaked somewhat. I am operating on the courteous assumption that basic elements, such as aspect ratio, were not significantly altered by Mr. Martin and his workmen.

 

Modelling this aeroplane required a couple of important sub-assmblies, difficult in themselves, which I have already gotten in hand.

 

First the motor, a representation of an early Curtiss V-8:

 

 

Its assembly may be found in this tread:

 

 

 

The second is the provision of spoke wheels, three of which are required. The matter was complicated by the small size of the wheels.

 

 

 

Their construction, and the method by which they were made and the tools and materials used, can be found here:

 

 

 

With these items in hand, and after some study of photographs, and period drawings of various contemporary Curtiss machines, I settled on dimensions and pattern for the wings. In these old 'flyers' produced by early designers in the U.S., the wings are the main structural element. Aside from motor and associated plumbing, there is not much besides sticks and strings (though there are a lot of those, the strings particularly). A rib spacing of 4.5mm provided a wing-span of 180mm, with a little fudge at the tips, scaling up to about 12.9 meters, or about 42' 6", measuring flying surface tip to tip, which is within the range of long-span Curtiss 'flyers' Mr. Martin would have been copying (spans given for Curtiss machines, by the way, often give the distance from aileron tip to aileron tip, not the span of the actual flying surfaces). I used the five foot basic chord usually employed by Curtiss. The 'ear' wingtips are Mr. Martin's; Cutiss wingtips generally were squared and ended at the outer bay of interplane struts.

 

The wings started out as blanks of .030" styrene sheet, cut to measure and bent by hand. After bending, they were sanded to a smooth curve surface. On the concave undersurfaces, this was done with heavy grit sandpaper fastened to a large bottle (about 4" in diameter), with a such paper on a smaller bottle (about 1" in diameter) used for final shaping. The upper surfaces were done with heavy grit sanding sticks. Once the shape was in hand, I began laying out the ribs.

 

 

 

I managed to cut myself a little cutting these out, but am of the school that blood sacrifice to the modelling deities secures some favor in a build....

 

Once the ribs were laid out, I 'broke the plane' between them with a narrow 'swizzle-stick' sanding stick, and the curved edge of a #10 blade used as a scraper perpendicular to the plastic. You don't need to go very deep, just enough to leave a 'ridge' readily apparent to your finger-tip brushed along the surface.

 

 

Once this had got a couple of coats of white primer, and a couple of coats of Future, the next step was applying rib tapes, quite literally in this instance: I used 1/64" pin-stripe cut masking tape. Fiendishly useful stuff, and I am beginning to look for resupply (the company is 'Line o' Tape') as I am now down to about half of my last 240' roll of it.

 

 

As will be seen in the photographs, Martin used a dark tape (possibly even blackened strips of wood or cane) to secure fabric to the ribs. I darkened the tapes with an ordinary #2 pencil. This then received two more coats of Future, which helps fix th tape down firmly, and seals the pencil marking. On the undersurface, it is only necessary to draw in the tapes, there is no need to 'break the plane'....

 

After this, I have begun to paint the fabric....

 

ey andan

 

Again, it will be clear from the photographs Martin used a pale fabric indeed. I have used a mix a light grey and tan, quite thinned, and brushed on between the ribs. It will get a couple more coats of this, but I will say the coverage looks more uniform to the eye than it does under flash and a macro lens.

 

Next step will be picking out which wing will be which, and beginning to assemble the motor and undercarriage to the piece chosen as the lower wing....

[Gorby]

Now that's real model making! Stunning work on a fascinating subject.

[TonyTiger66]

Another OM scratch build .

 

I always enjoy your builds, very well explained with interesting subjects and I always learn something new!

 

This is already no exception. Looking forward to this. Great stuff.

 

 

Best regards

TonyT

[Bonehammer]

Love scratchbuilds!

I'll sit in the corner armchair with an appropriate soundtrack...

[Tomoshenko]

Excellent work and good technique on those wheels.

[Martian]

This looks seriously interesting!

 

Martian

[Old Man]

8 hours ago, Gorby said:

Now that's real model making! Stunning work on a fascinating subject.

Thank you very much, Sir.

 

I stumbled onto this while looking into background on the Martin B-10 while preparing the write-up for a build of the old Williams Bros. kit of the 'air power wonder'. It was a fascinating rabbit-hole. I don't think I've set ot on a build with less information....

 

7 hours ago, TonyTiger66 said:

Another OM scratch build .

 

I always enjoy your builds, very well explained with interesting subjects and I always learn something new!

 

This is already no exception. Looking forward to this. Great stuff.

 

 

Best regards

TonyT

 

Thanks, Tony. I appreciate your interest and your kind words. With the wheels and motor in hand, this should not be too difficult. It will have to be fastened to its base, though: no way to get enough weight up front to keep it from being a tail-sitter.

 

7 hours ago, Bonehammer said:

Love scratchbuilds!

I'll sit in the corner armchair with an appropriate soundtrack...

 

Thank you, Sir!

 

And if you want to extend your sound-track....

 

 

 

I love this stuff....

[Old Man]

7 hours ago, Tomoshenko said:

Excellent work and good technique on those wheels.

 

Thank you very much, Sir.

 

Spoke wheels are kind of a Holy Grail for modeling the early days. The method can be scaled up for larger diameter wheels; tube is available in 9.5mm and 11mm sizes that I know of, and it certainly possible to produce rings and plungers to various sizes.

 

6 hours ago, Martian Hale said:

This looks seriously interesting!

 

Martian

 

Thank you, Sir.

 

I am glad to have gotten onto making the actual flying bits of it....

 

[Old Man]

Have been working away on this, though there have been some distractions (some of them posted up here recently).

When last seen, things were just painted wings

 

First, I painted the motor, and constructed the cradle on which it rests atop the lower wing, and contrived a radiator.
 

 

The motor was painted silver, then gone over with various rust-red and orange washes to give it a copper tone. The radiator is basically a rectangle of thick sheet, wit edges and top added from bits of rod and strip. It was painted as was the motor, but with yellow tining on the frame, for brass.

Here is the cradle and motor on the wing.
 

 

After painting the wood and metal tube elements of the cradle, I made the central girder portion of the undercarriage. I was guided by the scaled Putnam drawings of an early Curtiss, but angles and eye dictated final adjustments in length and such.

To give a sense of proportion, I tacked on a pilot figure for these next pictures, roughly where a pilot would sit, and I also slipped in the front spoke wheel (it is held in by the 'spring' of the converging structural members).

 

 

 

The central structural piece was over-long for handling, and trimmed back later.

Here things are painted, and the radiator is resting approximately where it will go.

 

 

 

After this came the tricky bit, which I will confess I put off a while, till last night things just seemed right --- putting on the rear wheels.

 

 

The difficulty should be obvious, getting those slanting bits with the fork ends to be the right angle and length so the the entire item would sit level when the wheels were on. All this had tobe done by eye, as I have no trust-worthy drawing. The little rod leading down on the starboard 'fork' is a visual aid -- it is cut to the length I decided was right (7.5mm down from the rear win spar) for the center of the wheels, and the 'forks' set by eye to match it. A lot of fiddling ensued, among other things I had to take these off to attach the wheels within the forks, and put them back on without benefit of the sighting rod. The forks are simply bent rod, and had to be pressed by tweezers onto the wheel axle ends. Then the various bracings where attached.

 

 

The vertical forks were assembled on the model, one length of rod with a bent end for each side, and the little cross-piece put once the verticals were assembled.

Here is a front view at this stage.

 

 

Next was putting in the final rear supports, and the 'fork' coming up to the nose wheel from the central element.

 

 

The sit strikes me as satisfactory. Next step will be doing the engine plumbing, and the seating arrangements..

[Corsairfoxfouruncle]

Incredible work 😳 ... very impressive.

[Brandy]

That's looking spectacular already, and It's not even half done! I love those wheels......

 

Ian

[Old Man]

19 hours ago, Corsairfoxfouruncle said:

Incredible work 😳 ... very impressive.

 

Thank you, Sir.

 

It is an odd item, I don't think I've ever done something with less by way of reference material.

15 hours ago, limeypilot said:

That's looking spectacular already, and It's not even half done! I love those wheels......

 

Ian

 

Thank you,Sir.

 

I like the wheels myself, and intend to set up for making more standard size ones by the same method of Great War and Golden Age subjects.

 

Rest of the weekend I expect to be working on my pair of Flycatchers. I am by no means out of the woods with 'El Sonora', but after the undercarriage, most of what's left is at least fairly normal modelling....

[Old Man]

 

 

After a hiatus from modelling I am only just coming out of, I am taking this project up again.

 

The first thing to do was sort out the seating arrangements. In the four photographs I have showing the seats more or less clearly, three distinct arrangements are shown: one with a passenger's seat to either side of the pilot (1 photo), one with a passenger's seat only to the pilot's left, but with other arrangements the same as the two passenger version (2 photos), and one with only a passenger's seat to the pilot's left, but with some differences in how the seats are supported (1 photo, and that taken later than the others). I am going with the version there are two photographs of, which is taken in 1913, when a contract pilot, Didier Masson, flew the machine.

I wince every time I handle this thing, and it took a bit of figuring to be able to test fit pieces. I finally hit on the idea of tacking bits in place with white glue, so that things could readily be taken off and put back without need for much force. So here are the seats and supports, tacked in place as rough pieces:

 

 

 

You can see at lower right some early tries at the seats, that were a bit oversized for this, but may prove useful later for some other project. The two cylinders at the left are blanks for the fuel tanks, that were slung alongside the motor. They are made from sprue left from an ICM 'old tool' I-15bis, which was half round in section, and providentially the same width as 'what looked right' in the pictures relative to the size of the men (measured off a pilot figure) suggested to my eye --- about 4mm diameter. There are a couple of halves nearby, and an earlier effort that proved a hair too short for the purpose.

Here at the parts for the seats, and the fuel tanks with their sumps and fastening bands, ready for painting and assembly to the model:

 

 

The long bit of rod slats up and out from near the wheel to the leading edge of the wing. The short piece of rod goes across the main girder to the 'extra' brace. The pilot's seat goes in front of this, on supports which rest on the main girder, the front of the passenger's seat is set on this, and its rear is set on the leading edge of the wing.

 

Here they all are painted and assembled:

 

 

 

This clears the way for getting the upper wing on. My usual course is to assemble from the center out, rigging as I go. I use EZ-Line elastic, attached with CA glue. People say this doesn't lend structural strength, but it does add some. The rigged wing-cell is usually much easier to handle than either of the individual wings.
 

[stevehnz]

Nice to see you back Old Man, I've missed your wonderful builds. I was reading my copy of Time Life's Soldiers of Fortune volume in their aviation series & one of the early chapters featured this or a very similar craft, so it is a nice coincidence to see this back in action. I shall look on with interest.

Steve.

[Old Man]

On 8/10/2020 at 2:38 AM, stevehnz said:

Nice to see you back Old Man, I've missed your wonderful builds. I was reading my copy of Time Life's Soldiers of Fortune volume in their aviation series & one of the early chapters featured this or a very similar craft, so it is a nice coincidence to see this back in action. I shall look on with interest.

Steve.

Thank you, Sir.

 

This was not the only aeroplane employed in Mexico at the time. At least Wright Flyer could be found, and the government (in various hands) had some Bleriot monoplanes as well. The revolutionaries generally hired pilots willing to take risks for specie, mostly from the U.S. Didier Masson was French, but a naturalized U.S. citizen. He was employed as a leading pilot by Mr. Martin, before signing on to fly 'El Sonora'.

[John Masters]

Welcome back!  I have followed your fine work since the Aerodrome Build Thread days...

[Old Man]

20 hours ago, John Masters said:

Welcome back!  I have followed your fine work since the Aerodrome Build Thread days...

Thank you, Sir.

 

I have fond memories of the old 'Drome as well. A shame what happened there. The site now for modelling Great War aeroplanes is this one:

 

https://forum.ww1aircraftmodels.com/index.php

 

There's some great work going on there.

[Old Man]

More progress on this now.

 

The upper wing is on!

 

 

 

 

 

Things aren't quite all Sir Garnet,  but it is acceptable, and most adjustments will be minor.

I dropped the booger twice, just in my lap, mind, but that was enough to spring things, as miniscule amounts of CA gel glue are all that is employed. The second drop came as I was trying to adjust position on the last strut (of course), and that one was bad enough I popped the wing off, and made new struts, which went on without further incident. As you can see I did not rig as I went, the thing was much too wobbly with four, or even eight struts in place, to hold while doing things like incidence wires. With sixteen struts in, it can be handled, albeit with some care. Painting struts, and rigging, are the next step, and this will include some minor strut adjustments, as things stiffen up with the pull of the elastic.

Once that is done something quite delicate will be needed. You may notice the radiator is off. This is because its position, relative to the forward tube supports of the motor's cradle, is too far back, and interferes with the proper forward 'cabane' structure (which is two parallel tubes, with a cross-piece and triangle at the top). The lower tube supports will have to be removed and placed a bit further back, and the cradle extended a trifle where the radiator goes. I feel reasonably confident I can manage this without undue difficulty. A new, thinner radiator piece may be needed.

I may also have to redo the rear outermost interplane struts, as these support (and go through) the mid-gap ailerons. It is just behind the leading edge, mind, and a notch with white-glue filler might suffice, but a hole may prove necessary. I confess I had not considered this when assembling the wing cell, but better to have plowed ahead and got the thing into one piece when the fit was on me and my blood was up.

Hope to have more progress in a week or so.

[Corsairfoxfouruncle]

Nice to see you back and this one on the bench again. 

[Old Man]

17 hours ago, Corsairfoxfouruncle said:

Nice to see you back and this one on the bench again. 

 

Thank you, Sir.

 

This is one of those things makes 'sunk cost' seem no fallacy. Enough went into this already it would be a shame not to take it all the way.

[clive_t]

Nice to see you back OM, and with a properly quirky subject. I am definitely pulling up a chair for this one!

[Old Man]

On 9/2/2020 at 12:10 PM, clive_t said:

Nice to see you back OM, and with a properly quirky subject. I am definitely pulling up a chair for this one!

Glad to see you looking in, Sir. I remember that marvelous 'Desert Grant Brew-Up' diorama you did.

 

I should have the rigging done this weekend, at least the wing-cell rigging. The surgery may wait a little, depending on mood, and other projects. I have a pile of builds near completion accumulated over the few years, and I want to get one of them done every so often.

Edited September 3, 2020 by Old Man

[clive_t]

Looking forward to seeing the rigging come together, I definitely don't envy you in your task.

Having looked back at the earlier progress pics, I am amazed at the level of detail on the engine. I had troubles enough doing something like this on a recent 'Canuck' conversion, and that was 1:48! In this scale, I'd have zero chance!

[Jonners]

Always good to see your WiPs, OM, as I learn something new every time. Re-reading the earlier part of your thread led me back to your spoked wheel tutorial, which I remember reading when originally posted and will be trying for myself - thanks! 

Jon

[Old Man]

On 9/4/2020 at 1:01 AM, clive_t said:

Looking forward to seeing the rigging come together, I definitely don't envy you in your task.

Having looked back at the earlier progress pics, I am amazed at the level of detail on the engine. I had troubles enough doing something like this on a recent 'Canuck' conversion, and that was 1:48! In this scale, I'd have zero chance!

Thank you, Sir.

 

Though I expect you would be able to manage it. Good tweezers help, as does a willingness to toss things that do not quite fit after all. Though I do on occasion find myself saying this would be a lot easier if I could see what I'm doing....