Quarter scale Kyutei Type 5 - RC Groups
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Feb 09, 2008, 04:06 AM
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Quarter scale Kyutei Type 5

Starting a build thread is one way to keep up one's motivation. So, here goes. Kyutei Type 5 was built in 1933 and was THE history making sailplane here in Japan. Its first major accomplishment was recording the very first over an hour flight here. It was also the very first glider to be aerotowed. With a span of 10 m, this plane should make an ideal first OD scale sailplane at quarter scale.
This will be a VERY VERY slow build. I do not have CAD capabilities, and will start manually drawing the plans tonight. Will post my progress as I build along.
Last edited by suirendoujin; Feb 09, 2008 at 06:48 AM.
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Feb 12, 2008, 07:38 AM
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Progress so far

Blew up the fuselage outline. I will add details as I build. Plan on using 10 mm square spruce for fuse longerons. Hope it will be strong enough.
Feb 12, 2008, 10:22 AM
Where's the lift?
dgliderguy's Avatar

I like it! Looks like a Pruefling, which is a candidate that I have considered for third-scale, someday.

It looks like it will be a fairly simple build, at quarter-scale, and it should look really nice in the air, with a clear-doped finish.

Will be following your progress here.

Feb 12, 2008, 08:31 PM
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This plane really made history here. Not only did it make the first over an hour flight, our version of the Vampyr here, it was also the first to be auto-towed and aero-towed. It also flew around the country aerotowed, promoting soaring. This plane has all the characters and quality one would look for in a first big scale project.
Type 7 is more popular, and was kitted in the past. Very similar to Grunau Baby. Schempf Hirth liked it when he came to Japan. Type 7 also set some records, and was the first glider to fly loops and mild aerobatics. Maybe my next project.
Feb 16, 2008, 12:07 AM
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Back to the drawing board

And I havent even started building yet. Looking at the photos and video images I have of Kyutei Type 5, the 3 views I had used to enlarge has a blunt nose compared to the real plane. Hmmmm. I guess its all part of the fun.
Feb 19, 2008, 07:08 AM
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Still working on the plans. Oh well.
May 09, 2008, 10:14 AM
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Still working on the plan

Those 3 views!!! No two 3 views make a complete match!!!!!!! My first fuse plan had a way tooooooooooooo broad a nose, although I did my enlarging correctly. No way thats correct, when compared to photos and video images I have. I guess it all boils down to a compromise between accuracey(?) and artistic reconstruction.
Last edited by suirendoujin; May 09, 2008 at 10:20 AM.
May 09, 2008, 03:43 PM
SB-28 UK Display Pilot
GeeW's Avatar
In full size gliders it is very common for there to be larger discepencies between individual airframes. Even production line build aircraft.
An example that I came acreoss when during my time of running a gliding club was that of our three K-13 two seaters there was a 115mm difference in the canopy lengths between them and no wing or tailplane would even remotely fit any of the others!
With Slingsby sailplanes it is much worse than that. I have had to inspect quite a number of Dart 17r's and have yet to find two the same.....even from a distance some of them don't look particularly similar.
With vintage types I tend to think the design is put largely on paper but the constructors only follow the plans when it suits them.....so whatever you do it will not be very far from the original.

Best Regards
May 09, 2008, 08:26 PM
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What an encouragement!

Thank you!!! So, vintage and modern sailplanes were a mix of industrial product and hand crafted art. Your comment really took a lot of load off my back.
Kyutei Type 5 was a one off plane. It was the first saliplane to soar using slope lift, and was also the first to fly for over an hour in Japan. With its constant chord wing, box kite like fuse, I chose it as an ideal first OD scale sailplane. While I tackle the plan, I will keep my VCR running and see it fly to obtain inspiration.
May 11, 2008, 01:17 PM
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Finished drawing the plan for the fuse and bulkheads. I hope I got it right, erh, at least, the way I think it should be. Will find out sooner or later. Fun never stops. And now its 2 Am, gotta work tomorrow. Gotta make a compromise somewhere.
May 14, 2008, 10:05 AM
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Drew up the stab plan last night, and worked on the wing plan tonight. Sudently, I have this feeling that this one is going to be a pretty BIG sailplane. Although its wingspan is 2.5 m or 100", a constant chord wing with a chord of 350 mm, 14", is no small wing!!!
Last edited by suirendoujin; May 16, 2008 at 08:08 AM.
May 15, 2008, 10:30 AM
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Goettingen 580 airffoil coordinates

I have posted this in the "Sailplane talk" forum, and was not so lucky so far. Anybody have any data on this vintage airfoil. This was the one used in the full scale Kyutei Type 5, and at quarter scale, why not use it! is my current thought. If you have any info, that would be greatly appreciated.
May 19, 2008, 08:02 AM
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Making tool of the trade.

While tinkering over wich airfoil to use on this scale sailplane, I felt the urge to smell some balsa dust last night. So, fabricated this tool to form the LE of the empennage. Scraps of hard wood, balsa, abrasive sheet, epoxy and micro balloon with a little help from medium CA. Tried it out tonight, and am happy with the results. I will be using 10 mm thick balsa for the empennage, so this little tool is destined to become my workhorse. Yep, its all about moving your hands and makin' things. Just thinking about it will never get you off the ground. Wont even take you to the flying site.
May 21, 2008, 10:41 AM
suirendoujin, for a 1:4 scale I would recommend you not use the Go 580. I think you will find the performance poor. You might consider the Go 549. This particular airfoil has been proven on 1:4 scale vintage sailplane models by several prestigious vintage sailplane builders
May 23, 2008, 07:28 AM
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I was out of town this couple of days, and was surprised to find exactly the type of post I was looking for! Can you provide me with examples of scale sailplanes this airfoil was used, so I will have more material to finalize my choice of airfoil to use?
Last edited by suirendoujin; May 23, 2008 at 10:03 AM.

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