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

[Old Man]

On 9/4/2020 at 2:06 AM, Jonners said:

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

Thank you very much, Sir.

 

Spoke wheels are a kind of 'holy grail' for models of the period. I gave a couple of photo-etch sets a try without success, and have even contemplated clear disks for a center, with wires laid down later with white glue.

 

The tube-plunger method does work, and on larger wheels I expect would be easier. These are much smaller than the wheels on latter machines. Tube in the 10mm range (plus or minus a little) would be required.

 

If you do try, please let me know how it goes.

[Old Man]

A strategic retreat has proved necessary here, but with reinforcement most of that has been retrieved. I expect much of the difficulty was that I am out of practice. My attempt at rigging this was a fiasco. I botched most attempts to attach the end of a line, and between cleaning up after failures and over handling of a quite fragile assembly, I was beginning to do harm. I stopped, and took off the wing.

I made stouter struts, and using the traces of previous attachments, put in some real locator holes, to receive a pointed end put on the struts. I took advantage of the monoplane interlude to re-position the front supports for the engine bearers

I have put in the first eight struts. The outer ones on the port wing have proved a tad longer than the rest, but this has been fixed subsequent to the pictures. Doing so benefited greatly from the greater solidity. The rigging towards the center is the most tricky, because the places you naturally want to hold to keep things steady you can't, because the fragile undercarriage is in the way. While I have not completely got the knack back, things did go easier once the inner incidence wires were in place.

At any rate, here it is as of a couple hours ago.

 

 

 

Once the struts in place are fully rigged I will add the next bay, and then tend to the tubular bracings in the center. I think I should leave off the outermost pairs till I have the mid-gap ailerons sorted out.

[Old Man]

Lost ground has been recouped and more now.

 

 

Strut length has been adjust here and there, after rigging was in place. The outer bay landing wires (from high inboard to low outboard) are functional. They are deliberately short, and pull the wing structure up and level. This will be repeated with the final bay. I have left this off for now, because I need to dope out the aileron arrangement. Matti64 was kind enough to send some good Curtiss drawings that are a godsend for that.

 

Once the rigging was done, I could do the tubular arrangements in the center section.

 

 

 

This is 0.6mm rod, and matches up with existing pieces. The triangle is got by bending ends of two lengths of rod. I had previously cut a little length of rod the matched the width the verticals had to be apart. I placed this on some two-sided tape, and fiddled with the bent rod stuck down on the tape till I had it right in relation to this standard width. Then the crosspiece could be trimmed to fit. A dab of CA gel, and then douse things in accelerator. This, I found by happy accident (I swear I've spilt more of this stuff than I've actually used) obliterates the tack of any tape quickly. So the assembled piece can just be lifted up and rinsed.

 

The lower portion of one of the rear supports is a bit askew. I will leave it for now, but will think again when assembling the tail. That's a bit down the road --- 'cockpit' arrangements, controls and such, ailerons, radiators, and forward stabilizer arrangements are the order of the day.

 

 

Rigging is slowly coming back to me. Got my failure rate down to about one in four from four in five. Once all the lines were in, I trimmed down the struts a bit by scraping with a blade's edge. With color on they look all right to me.

Edited September 17, 2020 by Old Man

[stevehnz]

A good recovery there OM, this is looking the part really nicely now.

Steve.

[clive_t]

Well done on the recovery sir, I am looking forward to the next instalment

[Old Man]

14 hours ago, stevehnz said:

A good recovery there OM, this is looking the part really nicely now.

Steve.

 

9 hours ago, clive_t said:

Well done on the recovery sir, I am looking forward to the next instalment

 

Thanks, guys. I am feeling a lot better about the prospects for this. The ailerons are mid-gap, and their middle is the rear outermost interplane strut. They have a pivot of some sort at the rear strut of the bay furthest out now. I suspect the extra weight of the ailerons may be balanced out by their rigid (in the model) attachment to two struts. Another oddity about the ailerons is their control. There is a sort of 'seat back' for the pilot's torso, with something like a reversed bicycle handle bars, whose grips go under the pilot's armpits. The pilot leaned his body to work the ailerons, like you would lean turning on a bicycle.

[Jonners]

I'm really glad this progressing so nicely, as it's a cracking subject. Unusual and adventurous.

 

10 minutes ago, Old Man said:

There is a sort of 'seat back' for the pilot's torso, with something like a reversed bicycle handle bars, whose grips go under the pilot's armpits. The pilot leaned his body to work the ailerons, like you would lean turning on a bicycle.

Intriguing. I suppose in 1913 designers (inventors?) were still trying out control ideas that, although quirky, must have seemed quite intuitive to them. I suppise it isn't especially different from comparing today's weightshift/flexwing and 3-axis microlight aircraft.

 

Jon

[Old Man]

1 hour ago, Jonners said:

I'm really glad this progressing so nicely, as it's a cracking subject. Unusual and adventurous.

 

Intriguing. I suppose in 1913 designers (inventors?) were still trying out control ideas that, although quirky, must have seemed quite intuitive to them. I suppise it isn't especially different from comparing today's weightshift/flexwing and 3-axis microlight aircraft.

 

Jon

 

Part of it was a patent fight, Sir. The Wrights claimed to have patented directional control, that their wing-warping patent covered every means of adjusting effective airfoil to induce a bank. Curtiss sought to show his 'ailerons' differed from the Wrights' patent, which is one reason they went mid-gap. The Wrights controlled bank by two sticks, one in each hand, and Curtiss devised his 'yoke' control. Couldn't be more different, eh? Curtiss and the Wrights fought this out in court a good while, and this seems one reason aeronautics did not advance much in the United States, past the initial breakthrough. Eventually courts upheld the Wrights, but by then it was too late, they were dwindling and Curtiss had the trade and the public.

 

I think you are right about intuition, though, and offer in backing it that Curtiss began as a dare-devil motorcycle artiste, and leaning into a turn must have been second nature.

[Jonners]

Well, I've been flying for 32 years - 27 of them professionally - and I didn't know that. Every day's a school day!

[Old Man]

21 hours ago, Jonners said:

Well, I've been flying for 32 years - 27 of them professionally - and I didn't know that. Every day's a school day!

 

I had no idea either, till I started looking into this project. Part of the fun, in my view.