RYAN STA 1/18

[RLWP]

43 minutes ago, Buster99 said:

Hello Geoff, indeed a beautiful plane!

And yes, the span would have to be slightly increased in order to have the same span as drawn when viewing from the top. Looking from the front the dihedral forms the hypothenuse of a right angle triangle. The drawing forms the horizontal leg of the triangle and the distance that the wingtip is lifted from the horizontal forms the vertical leg of the triangle (Pythagorean theorem). As the hypothenuse will be slightly longer it will so correct the length in relation to the top view.

HTH, Marc

 

And if you work it out, you'll find the difference in length is pretty negligible. It's likely to be far less than the changes in length due to filing and smoothing the wing until it looks right

 

This is a model of an aeroplane, not a wind tunnel test piece. It has to look right, it doesn't necessarily need to be 100% dimensionally accurate (fortunately)

 

Richard

[Ironwing]

5 hours ago, Buster99 said:

Hello Geoff, indeed a beautiful plane!

And yes, the span would have to be slightly increased in order to have the same span as drawn when viewing from the top. Looking from the front the dihedral forms the hypothenuse of a right angle triangle. The drawing forms the horizontal leg of the triangle and the distance that the wingtip is lifted from the horizontal forms the vertical leg of the triangle (Pythagorean theorem). As the hypothenuse will be slightly longer it will so correct the length in relation to the top view.

HTH, Marc

Thank you Marc...

Edited April 23, 2021 by Ironwing
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[Ironwing]

Greetings All,

 

Some time has passed since the last update but not without some progress. The fuselage mold was finished and sent off to Tigger in the UK. The question became what to do next. I toyed a bit with a way to build the wing which was shown in the last update. Initially, using wing root to wing tip spars was the thinking because of weight concerns. Using the spars only approach would keep the weight of each wing to a minimum. The outboard wing attaches to a stub wing and frome what I can see, none of the stub wing penetrates the fuselage. Hence there is no structure to tie the two sides together. When you look into the fuselage of the ST-A, you see all the way to the bottom of the hull. The is no floor in the original airplanes other than small foot skids which lead to the rudder pedals. As you can see, there isnt much in there. The crank handle in the lower right of the photo raises and lowers the flaps to a maximum extension of forty-five degrees after thirty-two rotations of the handle. The handle drives a bicycle chain which activate the flaps. Im wondering if that curvilinear thing which spans the bottom of the fuselage houses the chain to the left wing. I dont really know.

 

Edited May 1, 2021 by Ironwing
spell check

[Ironwing]

The T shaped features at the top of the photo are the rudder pedals. The extensions off the inboard sides of the rudder pedals are heel brakes. While there are miriad photos of Ryans on the internet there is little that I've been able to find which chronicals the interior.

So "Damn the torpedoes..." move to the wing. To give the balsa core wing a look, ribs where fashioned from a card stock wafer. There would be six ribs per side to act as formers for the balsa core. 

A master template was made up from the drawing and used in final shaping of the rib stack after the stack was cut down using a small table top band saw. The band saw is immeasurably helpfull for such things in keeping cuts square and straight through thick objects. It does leave behind small a small amount of plastic melt but this can be wiped away with a finger...

The stack is the finished off with a sanding block...

I neglected to mention that the stack was held together using double sided tape. I originally wanted to make to make one band saw cut down the center of the stack to make top and bottom ribs but the stack became unstable so each had to be cut individually. This introduces some degree of irregularity but in the end it can be worked out with a sanding block once the ribs are in place.

Keep in mind, the ribs will only be used is the wing ends up with a balsa core.

 

The problem quickly became how to attach the wing to the fuselage without the advantage of a cross member to couple them.

A stub wing of sorts was made up off two of the fuselage formers as the original ST-A was done. There are four fuselage formers, two which were fashioned with mounting tabs which penetrate the fuselage wall outwardly only but remain integral to the fuselage and encorporate the four and a half degree dihedral. Yes, I checked with a protractor.

The same aproch was used as with the wing rib stack. Four pieces of .080 card were stacked using doubled tape. The fuselage former used to make the vacform mold was used to draw the former onto the stack and then the wing mounting tabs were added. The stack was then rough cut, but very close on the band saw and finished by hand with a sanding block and files.

The end result is four formers. All with wing mounting tabs. Two would have the tabs removed. The tabs are critically important. They generally need to be dead nuts in all aspects. If they arent exactly matched, the wings wont mount or align properly.

I picked the two that I thought came out the best to be refined in terms of the mounting tabs. The other two qould have the tabs removed and used as the numbers one(1) and four(4) fuselage formers.

I have to keep reminding myself that Im looking ate the inside of the fuselage and not the finished size. So, anyway, I spent time refining the the numbers two and three formers with the mounting tabs down to  tolerance of (+/.005")(-.000"). The tabs were worked in with the protractor.

Once the former shape was completed and each matched to each other at their respective datums and centerlines, a simple jig was made up in order to mount the formers so I could get a 3D look at the fuselage.

The acid test comes when the fuselage returns to see how it all fits together. The two wing mounting are shown. 

I should mention, when building the fuselage jig, it was taped down on a piece of glass to ensure that it was flat and the center keel was put against a steel straight edge to ensure starightness.

 

You can see how the wing outer section attaches to the wing stub and largely hangs off of the number two former. I shoud have maybe put this pic first..my bad

 

That wraps things up for this episode. I hope you've enjoyed it. 

I'll be back and next time, I'll bring cookies. Im off to do..something.

 

Hope everyone is well...be safe.

Best

Geoff

[Pete Fleischmann]

Good stuff Geoff!

 

cheers

Pete

[LSP_Kevin]

Terrific planning and execution, Geoff!

 

Kev

[MikeMaben]

That's pretty cool 

[Landrotten Highlander]

Cool idea, but I think the tab on the back one will be too thick, as the thickness of the wing is less at the back than it is at the front.

[Ironwing]

Hi Guys

Thank you much for looking in. I do genuinely appreciate your your responses.

Hope everyone is doing well...

Best

Geoff

 

 

[airscale]

I love seeing the birth of a project

 

I am on my first scratchbuild, and the freedom of thinking it gives is amazing - anything could be next, you are only limited by imagination, not kit manufacturers

 

..this is going to be something very special

 

Peter

[RLWP]

12 hours ago, airscale said:

I love seeing the birth of a project

 

I am on my first scratchbuild, and the freedom of thinking it gives is amazing - anything could be next, you are only limited by imagination, not kit manufacturers

 

..this is going to be something very special

 

Peter

 

I find there's something else about scratchbuilding, you are rarely correcting things, just making them new. No cutting off engines, filling and rescribing panels, filling gaps, making resin parts fit IM plastic parts

 

Richard

Edited May 3, 2021 by RLWP

[Ironwing]

Peter..Richard

 

Thanks for looking in...good to have you along. Scratch bulding, as you point out, is a very environment. We'll see what develops.

Best

Geoff

[Ironwing]

All,

Back at it again. Wing/fuselage mating remains the current effort. The first order was to make the adjustments to the wing mounting tabs, such that, they would engage the wing planform and provide the required dihedral and incidence. Not to be dramatic, but this is a critical point. If it wasnt done correctly, or as close as is humanly possible, the parts would be ruined or not allow the wings to seat in the correct position. The rear tabs had to be reduced (#3) in height to accomodate the thinner cord and a slice had to be made down the length of the tab to accept the wing center.

I was fortunate that the band saw blade gave me a kerf dimension close, but not greater than, the .030" requirement. Keeping it straight so as not to throw the dihedral off was understandably important. In hindsight, I could have used a steel straight edge as a guide. I would have gladly sacrificed its edge for the insurance. So the cuts were made and cleaned up by sliding a piece of folded 220 paper into it and doing that sanding thing. Number two (2) former wasnt a terrible experience. The number three(3) bulkhead required the same slit as number two(2) but lower down to accomodate the wing incidence of three degrees. 

Generally, the wing incidence (in the case of a model) isnt really important. In this instance, the wing forms a tangent with the bottom of the fuselage so it has to be there. 

The end result...

I added a bit of stock to the number three tab to be safe. It got pretty thin.

 

I think the dihedral came out within acceptable limits. Cant really see the incidence but its there.

 

How it all looks at this point...

[Ironwing]

Thats about it for today. I know, its not flashy or colorful but its necessary. Someplace in there I hope to find an ST_A..hang in there.

I hope everyone is well...stay safe.

 

Best

Geoff

[D.B. Andrus]

Geoff,

 

Your build is very inspiring and well done. As I'm in the exploration stages for a somewhat similar project, albeit in 1/32, am soaking up everything you do. I know you're excited about the STA and it's contagious.  Look forward to every update.

 

Cheers,

Damian