Marutaka/Royal Stearman Rebuild - RC Groups
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Dec 18, 2009, 05:28 AM
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I. Klemetti's Avatar
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Marutaka/Royal Stearman Rebuild


A couple of years ago, I purchased a ready-built Marutaka Stearman. Wing span 1736 mm (68"), scale 1/5.65.

Although declared as airworthy, it was far from such. When buying the model I was aware of that so no disappointments here.

I removed all the gear and ripped off the covering. I found a lot of 3 mm (1/8") plywood in the model. Way too much. And mostly in wrong place: in the tail end. I managed to grind off 200 g from the tail. That means I can save 800 g in nose weight, making a total of 1 kg saving in total weight. Not too bad.

For a new engine I purchased a Titan ZG 20.

/ilkka/
Last edited by I. Klemetti; Nov 09, 2010 at 12:47 AM. Reason: Title edited
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Dec 19, 2009, 01:32 PM
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A very distinctive feature in a Stearman is its uncowled radial engine. As I was able to find some Williams Bros plastic scale cylinders I decided to build a better fake engine.

The crankcase is made from balsa and plywood.

The cylinders are for 1/6 scale Pratt & Whitney Wasp. The Wasp is larger than the Continental W670 I wanted to model. However, the cylinders' slightly smaller scale compensates for the size difference perfectly. I reversed the valve covers to get the pushrods on the backside like they are on Continental. I also had to re-engineer the intake and exhaust pipes locations. The Williams kits provided a lot of plastic nuts which I could utilize to decorate the crankcase.

/ilkka/
Dec 22, 2009, 01:36 AM
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The instrument panels are quite a visible feature on a Stearman. I made the panels from balsa sheet, some overhead projector film and solder. The gauge faces are laser printed images of real instruments. The screw heads were made from drops of white glue. The weight of the panels is 4 g each.

/ilkka/
Jan 02, 2010, 08:30 AM
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Too cold to get the garage warmed up for sanding and painting jobs. An activity suitable for indoors is making the rib stitching.

I ironed narrow strips of Solartex on the plain Solartex covering and simulated the stitchings with white glue dosed from a syringe. The whole was then covered with Toni Clark (Germany) pinking tape. The tape material is like soft and thin vinyl sticker with glue on backside.

Now that I have practiced on the undersides I can proceed to the upper surfaces.

/ilkka/
Jan 02, 2010, 09:29 AM
AND FOR MY NEXT TRICK....!
jodini's Avatar
I didn't want you to think no one was watching! Cool plane and some great details going into it! I love that radial engine! Nice job!
Jan 03, 2010, 05:59 AM
ARFs Are Me
TomCrump's Avatar
Thanks for showing us how you made the radial.

I have some Williams Bros cylinders, and plant to do something similar.

You've given me a few ideas.

Thanks !!!
Jan 06, 2010, 07:26 AM
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I. Klemetti's Avatar
Jodini and Tom, I just want you to know that your threads on RCGroups are endless sources of inspiration for me. I'm reading them regularly and learn something new almoset every time. Thanks for your contribution.

I didn't know how hard it is to find a pilot bust of right size and style. I needed '40s American military training pilots. Unable to find ones I decided to try to make them.

I managed to get a handful of used Action Man style figures for a couple of euros. However I needed little larger pilots. So I cut off the faces of the dolls and made slightly bigger heads from foam. The smaller scale faces were a perfect fit to larger scale heads.

Next step was to collect some pairless socks to make turtleneck and scarf. The leather jackets were made from -- leather. There is no sewing involved, it's just cut 'n paste affair. The zipper is electrical wire strand wound around a pin and then stretched. If you want the zipper really mesh remember to wind the pairs in opposite directions

The older guy will sit in the rear cockpit and he is leaning a bit to the left and looking to the left. He'll fly the airplane. The younger dude is looking straight forward and watching the RPM gauge (on the ground) or the airspeed indicator (in the air).

They weigh 19 grams apiece. The plastic face alone is 6 grams.

/ilkka/
Jan 06, 2010, 08:04 AM
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TomCrump's Avatar
Boy, I'm glad that I'm subscribed to this thread !!!
Jan 06, 2010, 08:51 PM
AND FOR MY NEXT TRICK....!
jodini's Avatar
WOW! You do some amazing work! You should sell those pilots! Great idea!
Jan 10, 2010, 06:40 AM
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I. Klemetti's Avatar
Quote:
Originally Posted by jodini
You should sell those pilots!
These individuals will definitely be for sale if they won't learn how to fly a Stearman.

To further postpone sanding and painting I tinkered with the windscreens. After making a cardboard template I cut out the transparent parts. I scored the plastic at the fold on the outer surface and bent to shape. Filling the (scored) groove with epoxy made the bends quite solid.

The frames were cut from litho plate. Very easy material to cut, just regular scissors will do. Litho plate aluminum is easy to form, too. You don't need any special tools, just a clamp and a pair of sharp edged pieces of wood.

I tack glued the windscreens on the fuselage and assembled the frames in situ. Due to this construction method they became a perfect match to the fuse. Total weght for two windscreens is 15 grams.

/ilkka/
Last edited by I. Klemetti; Jan 11, 2010 at 05:36 AM.
Jan 10, 2010, 06:44 AM
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TomCrump's Avatar
Nice work. You're very talented !!!
Jan 23, 2010, 08:38 AM
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Thanks, Tom. You are so polite, as usual.

Plain model airplane wheels with collars visible don't look very scale. So I fabricated wheel covers and brake backplates from balsa to hide collars and make the illusion of larger diameter wheels. The discs are tissue covered on both sides for strength.

The fake suspension links are from plywood and balsa. Everything will be painted later...

/ilkka/
Jan 23, 2010, 11:08 AM
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TomCrump's Avatar
You're adding some great details ! What's next ?
Jan 23, 2010, 11:31 AM
Buildin' fool
Twinwarbirdflier's Avatar
Great Job Mr. Klemetti!
Jan 31, 2010, 04:45 AM
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I. Klemetti's Avatar
Quote:
Originally Posted by TomCrump
What's next ?
The airplane itself, I'm afraid.

I painted the rudder from a rattle can to see how the rib stitching works out. First timer as I am I am very pleased with the result. I have never had such a beautiful rudder before. It definitely pays of to follow you masters' build threads. Thanks a lot for teaching.

The fuel lines on the upper wing has to be removable as the wing is one piece without a separate center section. I attached the sumps with small magnets and some aligning pins. The fuel gauge is removable too. You don't expect it to remain intact during transport if it were permanently attached.

/ilkka/


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