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Old Apr 01, 2012, 09:05 PM
Semper Fly
Marineair's Avatar
United States, ID, Meridian
Joined Oct 2004
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Peter Rakes Ryan PT-22

The Ryan PT-22 has been one of my favorite aircraft since seeing one fly at the Watsonville Antique Fly-In back in the early 80's. I instanly fell in love with the sleek polished aluminum fuselage with the swept back yellow wings.. Then there was the distinctive sound of the Kinner radial. It idles so slowly that it seems you could count the pistons firing. Still one of my favorite engine sounds.

When Peter Rake asked for suggestions for a project I figured I 'd put in a request for the PT-22 and see if he'd be interested. I don't know if it was my offer to paint his house and walk his dog, or interest to see this aircraft modeled that pushed him to do the design, I'd like to think it was the former, but alas he is a close lipped chap so we may never know.

The PT-22 evolved from the Ryan ST/STA (Standard Trainer And Standard Trainer Aerobatic) which were powered by the Menasco six cylinder engine. It seems the aerobatic capabilities of the STA, caught the eye of the US Army. Some changes were called for to militarize the STA including replacing the more fragile Menasco engine with the more robust Kinner radial. The longeron running between the top of the cockpits was also moved outboard to facilitate the pilots wearing parachutes. This resulted in the PT-22 weighing 400 lbs more than the STA. These and other modifications nessescitated sweeping the wings back 4 degrees 10 minutes to maintain CG.

All of these modifications resulted in a Primary Trainer with a nasty reputation for wanting to spin in stalls followed by wanting to spin in the opposite direction as spin recovery was attempted by novice pilots.

In the Air Progress flight report on the PT-22 the pilots interviewed stated that of the type had been designated BT-22 or AT-22 it would have had a better reputation as a trainer as its flight characteristics more closely resembled the Vultee BT-13 or the North American AT-6.

Well enough of my inane babbling, sit in some popcorn grab a chair to nibble on and lets get on with the build.

PS. Any tips, advice, critiques are very welcome, I plan on learning alot on this build and any and all help is appreciated.

PPS. Any verbal abuse, sarcasm, browbeating or insults will be graded.

PPPS. This will be a dual prototype build with kdahlhaus building a second PT-22.


Cheers
Scott
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Last edited by Marineair; Apr 03, 2012 at 01:22 AM.
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Old Apr 01, 2012, 09:07 PM
Semper Fly
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United States, ID, Meridian
Joined Oct 2004
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Here is a rundown of the equipment I'll be using.

I'll use HS65HB servos for all controll surfaces except the rudder which will be outfitted with an HS65MG to handel the load from the tail wheel.

The ESC will be a Castle Creations Thunderbird 54. I really like their reliability I've only had one of their ESC's fail and it was five years old and abused.

For power I'll use an E-flite Power 10 I've had lying dormant for too long.

I'm leaning towards a 12X6 wooden prop. IIRC Master Airscrew made some that might look kind of scale.

I'm shooting for a ready to fly weight of around three pounds E-flite claims the Power 10 producs 430w swinging a 12X6. If that is close to reality there should be plenty of power for good scale flights. Lets hope there are no scale stalls and spins!
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Old Apr 01, 2012, 11:55 PM
Falling with style!
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Old Apr 02, 2012, 02:49 AM
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Scott,
All I'm prepared to say is that the wife is considering shades of warm orange for the dining room and Fergus (a Westie) is looking very eagerly at his lead.

Mind you, I do wish you'd mentioned the type's bad reputation earlier. Now I shall worry even more as maiden time approaches. Oh well, time will tell.
Sorry it took so long to actually get drawn. Now that it is, is it what you were hoping for?

Pete
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Old Apr 02, 2012, 09:16 PM
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United States, ID, Meridian
Joined Oct 2004
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Tell the wife and Fergus to hold tight help is on the way. On second thought the wife could hold out far longer than Fergus!

The PT's reputation stemmed from the additional 400 lbs the Army added to it. As long as the wing loading isn't scale I think we'll end up with a fine flier.

I was actually quite surprised you got around to drawing this so quickly as I expected it to be pretty far down your to do list.

It is just what I was hoping for, possibly more. Can't wait to try the horizontal crutch fuse build. I'm kind of a masochist and enjoy laminating wingtips and tail feathers. What I really like is the simplicity of your design with all the character of the real plane.

Hmmm seems like I remember someone writing something like that in some UK mag.
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Old Apr 02, 2012, 09:36 PM
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Pete, scale wise can I still use the plastic 5 cyl motor we ship with the Ryan's Daughters?

If there is a lot of demand for it we can start offering the ply and balsa motors again too.

charlie
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Old Apr 03, 2012, 02:43 AM
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Charlie
When you get ready to send the laser cut parts I'll add a set of the plastic cylinders to my order. From eyeballing the cylinders on the Ryans Daughter they look a bit small but it's hard to tell without having them in hand. I'll also pick up one of Sparky's 7 cylinder radials (Wright Whirlwind ?) and see which is closer to scale.

How close are the sizes of the plastic RD cylinders and the ply and balsa ones?

Thinking way into the future.
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Old Apr 03, 2012, 04:14 AM
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Norfolk, England
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Charlie,
I included the cylinder parts on the cut file, but have no problem if the guys want to use the vac-fomed job. The cylinders I show are virtually the same as the RD ones, just a little taller, and looking at Sparky's engines cutting them a bit longer should be no problem.

As regards size, having traced over the three view cylinder, and enlarged that to match the model's scale, you'd have to start measuring to see any difference in size from the RD cylinders. That mostly involves the head being thicker. So, since that won't be an issue with the vac-formed cylinders, and assuming they are the same size as the RD ones, it should work well.
Is it the 6" engine that you use?

Pete
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Old Apr 03, 2012, 08:56 AM
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It is the 6" one. Reduces cost by $15-$20.
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Old Apr 03, 2012, 12:25 PM
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United States, ID, Meridian
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I don't have the kit in my hands yet so it seemed some stripper time was called for. The outlines of the tail group as well as the wingtips are made from laminations. The plans call for the laminations to be made from 1/16 X ¼ balsa. After few minutes with the stripper I had a nice pile of lamination strips.

I started with the rudder since it was the part of the plan closest to me. I usually cut formers and tape the laminations to them. This time around I thought I'd try the perimiter pinning method. I have a tool from Great Planes that you can use to press pins with, highly recommended to save your fingers when using this many pins.

I made the rudder seperate from the fin, they could be made as a single piece but the balsa sheet I have that seems right for bending is a bit short.

The strips were cut a bit oversized in case the laser cut bits or other wood in the framing is off.

The balsa used seemed soft enough so I decided to have a go at spraying them with windex instead of soaking them in hot water. After a few minutes I tried a little prebending and they were deemed soft enough to laminate. After a quick wipe down to dry them off a bit a smear of Gorilla wood glue was applied and they were pinned around the outline.
Scott
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Old Apr 03, 2012, 12:30 PM
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A Bit of "Atmosphere" for the Discussion...

While Kinner is a topic:



I too love the sound of the Kinner radials! As well, there is a "look" about them that is distinctive...

James
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Old Apr 03, 2012, 03:52 PM
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USA, WA, Freeland
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Quote:
Originally Posted by Deuce View Post
While Kinner is a topic:



I too love the sound of the Kinner radials! As well, there is a "look" about them that is distinctive...

James
If you listen closely to a Kinner at idle, you'll recognize that it talks to you. It says: Chickenplucker, chickenplucker, chickenplucker...
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Old Apr 03, 2012, 08:55 PM
Semper Fly
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United States, ID, Meridian
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Quote:
Originally Posted by Rick Ludtke View Post
If you listen closely to a Kinner at idle, you'll recognize that it talks to you. It says: Chickenplucker, chickenplucker, chickenplucker...
Thats not what my dad told me they say!

Scott
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Old Apr 03, 2012, 08:56 PM
Semper Fly
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James, welcome aboard. That shot of the Kinner is going to be my new wallpaper .

Scott
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Old Apr 04, 2012, 02:38 AM
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United States, ID, Meridian
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Pete
I was staring mindlessly at the plans while waiting for glue to dry on the laminations I did tonight and I noticed two things.

The first is just a typo. The rudder lamination calls for "4 off 1/4x1/4 balsa". It should read "4 off 1/16x1/4 balsa". I only point this out because I know people who would try to laminate a
2" thick rudder!

The second is on the fuse sheet the wing strut measures about 1/2" while on the wing plan the strut covering the wire is 1/4". Which of these is more correct?
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