Scratchbuilding a 1/32 1927 Ford AT-4 Trimotor

[Skyking]

I am about ready to begin my next project, a 1/32nd scale Ford Trimotor. My plan is to use a corrugated aluminum material from K&S Engineering that's .002" thick, with .060" spacing of the corrugated skin, over a basswood or Ren-Shape core. The majority of the airplane is a flat, slab-sided box, so cladding that type of structure should pose no problems. The only curved areas are the wing lead edges, so I was a bit concerned about getting the aluminum to wrap around without kinking or bending. I ordered a package for testing purposes and to see how workable it is. It arrived today, and the results you see here are after about 45 seconds of fiddle-dinking around with it.

Here's the package as it arrived. The panels are 5x7 in size, with two to a pack. I guestimate I'll need about 10 packs to clad the model.

This test piece is about 1" wide by 3" long. I made the radius by gently rolling it over a section of scrap balsa wing section I used on an old build.

Here's the final panel. I will use contact cement to apply the cladding to the substrate, which will be either basswood or Ren-Shape.

Needless to say, all my worries and concerns were for naught, as this stuff took a pretty sharp radius (3/8's of an inch) without so much as a dimple, wrinkle, kink or deformation. It's pretty soft stuff and bends and shapes easily, plus I can cut it with scissors and it doesn't crush. This just might be the bee's knees. I am waiting for my drawings to arrive so I can make a test wing section for further trials, but I really think I can pull this one off now. I'll post some more pictures as I progress, once I start making the airframe pieces and other items.

Stay tuned.

Cheers

Mike

Edited December 14, 2009 by Skyking

[cornfedrat]

Neat...I'll definatley be keeping an eye on your build as the Tri-motor was the first aircraft I ever took a ride in.

Mike

[tornado64]

Neat...I'll definatley be keeping an eye on your build as the Tri-motor was the first aircraft I ever took a ride in.

Mike

horse and cart to the airfield , beer was a penny a pint , you could go to the pictures buy ten woodbines , have fish and chips after being in the pub and still have change from 10 pence !!

seriously though what a cool plane to take a first flight in !!

[BOC262]

That corrugated material is going to help you make a very impressive model! Good luck with it. I'm sure it will be a stunner!

Question about the Ren-shape--do you have a source for smaller quantities of it, or is it still only sold per whole slab?

[cornfedrat]

horse and cart to the airfield , beer was a penny a pint , you could go to the pictures buy ten woodbines , have fish and chips after being in the pub and still have change from 10 pence !!

seriously though what a cool plane to take a first flight in !!

Not IN 1929 lol, It was 1993 and I was 7. But I still remember it well, $20 a head to take a trip from the Ankeny, IA airport, over the antique tractor show grounds, head over the mixmaster to downtown Des Moines and back, prolly 50 min in the air. Good deal, and lots of fun for a kid.

[tornado64]

Not IN 1929 lol, It was 1993 and I was 7. But I still remember it well, $20 a head to take a trip from the Ankeny, IA airport, over the antique tractor show grounds, head over the mixmaster to downtown Des Moines and back, prolly 50 min in the air. Good deal, and lots of fun for a kid.

i know i was winding you up , that must have been one uber cool flight though !!

[cornfedrat]

Spent the first couple minutes getting my stomach out of my throat. After that I was good, and to this day the sound of a radial makes me shiver...lol

[HOLMES]

Skyking/Mike

I am looking forward to this build as I DID your last one...

hoo hooo

HOLMES

[Fishwelding]

horse and cart to the airfield , beer was a penny a pint , you could go to the pictures buy ten woodbines , have fish and chips after being in the pub and still have change from 10 pence !!

Of course, in the United States, beer was then illegal under the Volstead Act.

Skyking, I'll be interested to see how this turns out. I'd like to see a bigger plastic kit of this bird than Revell's old (but admittedly, not bad) 1/77th scale kit.

Edited November 3, 2009 by Fishwelding

[tornado64]

Of course, in the United States, beer was then illegal under the Volstead Act.

Skyking, I'll be interested to see how this turns out. I'd like to see a bigger plastic kit of this bird than Revell's old (but admittedly, not bad) 1/77th scale kit.

i have two in my stash ( one i know is an airfix ) the other may be revell i havn't looked but you can build into an arctic exploring version with dog sled, dogs, figures and a trimotor on skis !!

[Skyking]

Hiya Mike. Wow what an airplane for your first ride. That had to be pretty exciting. I'm envious.

Question about the Ren-shape--do you have a source for smaller quantities of it, or is it still only sold per whole slab?

Hiya BOC. I am lucky. I get cast offs and scrap from a local shop that uses it for 3D prototyping. They have minimal sizes that they can use, so anything smaller I get. I've got some chunks that are 4 feet long, 3 inchest thick and 12 inches wide.

Thanks Holmes. Glad to have you and everyone else along.

My drawings arrived Tuesday, so I'm about to cut some practice parts and see how this stuff will work. I'll post some pictures sometime this weekend.

Cheers

Mike

[BOC262]

... I've got some chunks that are 4 feet long, 3 inchest thick and 12 inches wide....

Whoa, that will accommodate some VERY interesting projects--LOL!

When I used to buy Ren-shape the minimum size I could get was about 2 inches by 12 inches by 5 feet (IIRC). Cost was somewhere in the neighborhood of $200. Very justifiable for a business, not so much for a hobby.

Thanks for your reply and good luck with this project. I will be watching with great interest.

Karl

[cornfedrat]

Can't say I've ever heard of the Renshape stuff till today...good to know

[Skyking]

Tonight I got my first practice part done... the Rudder. This is my first time using Ren Shape. Up until now I've always used basswood to carve my masters. Never again. This stuff is so easy to work with it's almost shameful.It sands easy, shapes easy, is dimensionally stable and my bandsaw blade doesn't "walk", because there's no grain. The only drawback is the dust from sanding feels almost like sand and gets every where, but it's easy to clean up. It does not finish as well, having a coarse texture to it even after sanding with 220 or 400, but this will be covered with aluminum so it's moot. It's also very light. I would guess it's maybe 50% lighter than the basswood for the same sized part, and that will be important for this build, as the cores will remain in place in the model, covered with aluminum.

I did cut two blanks for comparative purposes. Basswood is on the left, Ren-Shape on the right. My pattern is above. I had the Fin and Rudder sanded to shape with the Ren Shape in about 20 minutes. The basswood I gave up on after almost an hour just on the fin.

Not too bad for a practice piece. The rivets I did with a ponce wheel for the horizontal runs, and the verticals I did with my embossing tool and a straightedge, as they had to be in the "valleys" of the corrugations as the real aircraft is.

A couple of things I learned on this practice piece. I need to cut mt trail edges back about 2MM and sand them to a feather edge. or else I'll have a gap when the corrugated skin goes on. I also cannot use Contact Cement, as there's no forgiveness if you don't get it lined up exactly right the first time. What seems to work well is 5 minute epoxy smeared on the core, then holding the skin in place with tape, and sealing around the edges with CA and Accelerator. I used the same aluminum foil tape that Pierre used on his DC-3, and it works well for the end caps and other parts. It burnishes down well, and I can dress things up with a file if I need to.

This part is a bit rough, but it proves the concept that it can be done, and I feel a lot more confident in the build now. I'll carve another Rudder and use the fin I already have, and we'll see how they come out with the changes I know I have to make.

Thanks for looking

Cheers

Mike

Edited November 5, 2009 by Skyking

[BOC262]

...This is my first time using Ren Shape. Up until now I've always used basswood to carve my masters. Never again. This stuff is so easy to work with it's almost shameful.It sands easy, shapes easy, is dimensionally stable and my bandsaw blade doesn't "walk", because there's no grain. The only drawback is the dust from sanding feels almost like sand and gets every where, but it's easy to clean up. It does not finish as well, having a coarse texture to it even after sanding with 220 or 400, but this will be covered with aluminum so it's moot.

Based on the pictures you attached, I'm guessing the Ren-shape you are using is not 450--the stuff you have looks too "blonde". Ren-shape 450 is a light brown color--almost exactly the shade of powdered cocoa. If you can get your hands on some 450, you will proibably like it even more than what you've experienced so far--it can be wet sanded, so dust is no issue (except when sawing), and the surface, though a little porous, will take a perfectly smooth appearance when covered with an airbrushed layer of primer paint. I used to use Ren-shape for making masters for mold making and it was great for all the reasons you mentioned--in addition to be wet sandable.

Good luck with it--your project is looking great so far!

[Skyking]

Thanks for the comments BOC.

Based on the pictures you attached, I'm guessing the Ren-shape you are using is not 450--the stuff you have looks too "blonde".

I'm not sure what the number is... all I know is it's free, so it could be 903495803 and I wouldn't care..lol. I did a little more playing around with it and there's definately a learning curve. Power tools eat the stuff alive and it's very easy to take off too much material. Hand sanding with a block seems to work about the best and give the best control for finish work. A table saw or band saw works well for rough cutting, as you will see in my next update sometime this weekend. I've begun carving the fuselage Master, and I'll give a brief tutorial on how to take this...

and make an airplane out of it.

Cheers

Mike

[BOC262]

You probably have all the pix you need (I can see em in the background of your latest post), but I found this while surfing around, so FWIW, here it is:

[Skyking]

Hiya BOC

You probably have all the pix you need (I can see em in the background of your latest post), but I found this while surfing around, so FWIW, here it is:

*Right click Save AS* It's worth a lot BOC. I was wondering what the inner landing gear attachment looked like. You just answered it for me. Thanks much!

Before I can do an cladding, I have to have an airframe to put it on. Last night I began creating some very high quality saw dust and shavings, and at the end I hope to have a high quality master to vacuform my fuselage halves from. Here's a brief step by step on how I whack out a master.

This is where it starts. A 5 x 5 x 19 inch hunk of Renshape. Somewhere in there is a Fuselage. It's my job to find it.

First thing I do is rough cut the blank to general dimensions of width, hieght and length,leaving about 1/4 inch extra all the way around. I use my table saw for this, cutting a little more than halfway through on the first pass, flipping it over and parting it on the second. Normally I would have a featherboard and ripstop in place for safety, but this stuff cuts like a hot knife through butter. I used a piece of scrap and tried to force a kickback, and all it did was cut a wider kerf.

This is the results. The block on the right will be the Fuselage, the scrap on the left will become another project some day.

Here the laying out is started. I made extra copies of my drawings for the single purpose of cutting them apart to use as patterns. Here I have the side view stuck on with two sided tape. I have reference lines squared off and drawn on the block to have a constant starting point. Because my drawings did not have a top view, I had to map them out by hand. I drew a centerline down the top, from front to rear. I then measure off the bulkhead stations from my drawings and marked those points on the line. I then measured the widths of the bulkhead from the plans, and drew them with a square at each bulkhead station. After I connected them with lines to mark the outside, and presto.. my top profile.

Off to the bandsaw. I cut off the bottom first, keeping my blade just a smidge away from my pattern. I'll final sand the profile on my bench sander. I keep the bottom cutoff for the next step...

...the shaping of the sides. I no longer have a flat bottom to keep my cut square, so I reattached my bottom cutoff with a single screw from the bottom. This insures that my side cuts will remain square. Back to the bandsaw, same technique... keeping the blade just a hair from my lines.

Semi finished rough cut. I removed the bottom cutoff, put the side cutoff with my pattern back on, then cut the forward top profile. After I dressed up the sides, bottom and top on my disk sander, sanding right to the pattern and my lines on the top. My master is now to final dimension. All I have to do is shape the corners, windscreen and nose area.

First step is to lay out my wing location, based on my constant reference point, which is now the very front firewall bulkhead for the front engine. It's easier to mark it out and cut it now, while my sides are still flat, then after when I radius the top of the fuselage. My wing center section will pass through the fuselage, so that my wing will be one piece from tip to tip. Also marked out is the "ridge" where the top radius begins. I will lay a piece of tape along this to protect the sides, and use a sanding block to round over the top, sanding to the line.

A quick initial hole on the drill press with a 1/2 inch Forstner bit, then some more bandsaw work and the cutout is open. The opening does not have to be exact at this point, as I want to be able to adjust for alignment in the jigs to be built later. Once the fuselage is vacuformed, I will cut up the master in the interior areas, and epoxy the wing center section to it, fill the joint with epoxy and then clad it with the aluminum. I've also shaped the windscreen areas and rounded off the nose to the profiles indicated on the bulkhead plans, using pencil lines drawn on as guides.

OK all you eagle eyed steely nerved people, take a look at this head on view and tell me if you notice anything out of sorts, or not quite "right". After 4 hours of work to get this far, my eyes were beginning to cross and I couldn't see straight. Now is the time to fix things before I get too much further.

The next step will be to sand the radius on the aft portion of the master and mark out the cabin windows, do some filling and sanding of a couple of minor boo boo's, and I can set this aside and start the wings.

Thanks for following along. As always I'm open to suggestions or ideas on how to make things easier.

Cheers

Mike

[Liberator24]

This is the kind of stuff you just DO NOT imagine you would get on a free site like Steve's!! A start to finish on a UNBELIEVABLE project like a 1/32nd tri!! Looking good and I am definitely thankful to be seeing this go together!!!

-Jim

[BOC262]

Hi Mike,

Glad that nacelle pic was of some use to you.

Great craftsmanship and photo documentation!

Looks like you have a Grizzly table saw. That's my brand too--can't beat 'em for the money.

Are those Wylam plans? Looks like his style.

I stared at the front view pic of the nose. Looks like maybe the left side (right side in the pic) might be just a tad higher than the right--barely noticeable, maybe 2 swipes of a sanding stick will even it up.

Enjoy your project and have a great weekend!

Karl

Edited November 7, 2009 by BOC262

[Skyking]

HI Karl. Thanks for the comments. Liberator glad to have you tagging along.

Looks like you have a Grizzly table saw. That's my brand too--can't beat 'em for the money.

Are those Wylam plans? Looks like his style.

I stared at the front view pic of the nose. Looks like maybe the left side (right side in the pic) might be just a tad higher than the right--barely noticeable, maybe 2 swipes of a sanding stick will even it up.

No actually it's a General International, with an upgrade 50 inch Biesmyer fence. I also added a 30 inch side extension with drawers underneath, and a 40 inch outfeed table. When cutting sheet goods you can never have enough table space.

The plans are Clevelands. They make the only 4-AT plans I could find. Wylams are 5-AT, which was a bigger airplane. The 5's also had the verticle windscreens. I like the looks of the 4 better, plus the subject I am replicating looks like a chrome airplane with dark Navy Blue trim. It's an eye catcher.

Thanks for the eagle eye. I noticed it too after you pointed it out, and you were right, a few swipes was all it took.

Thanks Karl

Cheers

Mike

[BOC262]

Glad I could help--but I have a feeling you have this project well in hand--LOL!

A General TS?! NICE!

4-AT, 5-AT--looks like I have some reading to do. Thanks for the additional info.

She's going to be a beauty--have fun!

[martin_sam_2000]

This looks like it is going tobe a very interesting build. I love the look of this old timer.

if you need more references..I have a walkaround on my webpage here -->CLICK<--

hopefully they help you out

Sean

[richter111]

This is amazing, and I will be watching it. I love the metalwork already!

[Skyking]

Hiya Karl, thanks for the comments. There were actually several different models designed for Ford by Stout, but the 4AT and 5 AT were the most common.

Thanks for the link Sean. That is the aircraft I plan to replicate. The polished aluminum and dark blue trim is a real eye catcher.

Thanks for following along Richter. Hope you enjoy the show.

Last night I spent the time finishing the Fuselage master, shaping the rear portion and fixing the nits pointed out in the last pictures. I used my trusty block plane to do the initial shaping. I have much better control of a plane than I do a knife. I have the depth of my knife set to about 1/64th of an inch, so I have very good control of the amount of material removed. Once I got it roughly right, I used a block sander with 150 grit to bring to final shape, then hand sanded with 220 to a final finish. I also cut out the slot for the Elevator and Stabilizer while I was at it. Aerodynamic gap seals were non-existent on this airplane. With the exception of the ailerons, there's gaps and daylight showing everywhere.

Here's the plane in action. This stuff machines like butter, with paper thin shavings curling off the knife like a Shirley Temple bad hair day. There's something uniquely satisfying about shaping wood, or Renshape in this instance.

After final sanding, and removing the area for the Stabilizer, the fuselage is finished and ready to be vacu-formed. I will get all the other airframe parts done first before I do that.

This morning I wasn't in the mood to snort dust, so I spent the time and fabricated the Tailwheel struts and mountings. 1/16 brass tube and square tube was soldered up according to the dimensions on my plans and the pictures I am working from. The wheel came from the spares box. I flat spotted the bottom for a weighted appearance.

And here it is in place, with the Fin and Rudder temporarily pinned into position to check for clearence. Looks pretty good, with just the right amount of spacing and angles.

This slab is going to become the wing. At 28 inches it's a good sized wing span, and this is cut to size, plus about 1/4" all the way around. I will begin shaping this tonight, as I had to glue together two blanks to get the size I needed, and the glue needs to cure.

Thanks for following along. As always, critique and comments welcome.

Cheers

Mike