Another Gyronut Nube- PT-25 Kit Bash - RC Groups
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Jan 29, 2010, 01:25 PM
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Build Log

Another Gyronut Nube- PT-25 Kit Bash

Well I have to say that Autogyros have always intrigued me and I finally bit the bullet and bought a FlyingBalsa PT-25. Being one who dispises ARFs, it is refreshing to see that there are high quality kits out there and I have to say that I am duly impressed with the quality of this kit. From Cox and Sterling PT-19s in my C/L days (long ago) to a completed Avonds F-15 turbine aircraft, I can't count how many I've built.

I really liked this kit and the quality of the balsa, the design, and the precision that this thing goes together.

So far the only thing I would have done a little different is glue the torque blocks for the landing gear and the triangle between the fuse sides and firewall before installing the 1" fuse portion in front of the tank hatch. it would have just been a touch easier and it's a very minor detail.

I will also be adding a somewhat scale look to the fuse and will pull from the British Kay Autogyro for inspiration. My PT will retain the stock hatches with contoured fuse sections attached by rare earth magnets.
Last edited by topgun2mo; Feb 07, 2010 at 12:11 AM.
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Jan 29, 2010, 01:40 PM
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Fool Proof Blade Construction

For those with a drill press, I think I have a way to ensure error proof blade construction.

First using a 3/16 or larger piece of piano wire, check the square of the drill press table in both axis.

Cut out the blade doublers, drill the holes to #33 size and sand the doublers lightly to remove any roughness around hole or the edge.

Chuck up the #33 drill bit upside down (smooth shaft sticking out of the chuck) and ensuring the top blade doubler is positioned correctly, slide the doubler up the bit towards the drill chuck (out of the way). Also slide the bushing onto the bit.

Rest the blade on a 3/4" board about 12" long with the slight undercambered portion of the blade hanging over the boad to ensure the blade is flat with the table and the hole in the blade is over the wood support. Raise the table so the drill bit just contacts the wood support.

Using the drill bit as a guide, "press" the bushing into the blade ensuring the bushing is flush with the top of the blade and your bushing will have been installed square to the blade bottom edge.

Slide the blade doubler down and hold it into position and apply thin CA. Wipe excess.

Lower table and remove bushing, blade and upper doubler assy. Install bolt into lower blade doubler and position on bottom of blade and apply thin CA and wipe excess.

Repeat for other 2 blades
Jan 30, 2010, 01:44 AM
jodini's Avatar
The PT-25 kit is probably the closest thing you are going to find for an ARF for a gyro. It goes together quick and he tells you exactly what to do for set-up.

Would love to see some pictures of your progress!
Jan 30, 2010, 12:52 PM
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I'll start posting pics when I start doing the shaping of the fuse. All the rest has probably been posted before.
Feb 02, 2010, 02:45 PM
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Here goes some pics.

First I layed out my fuse design
Feb 02, 2010, 11:49 PM
jodini's Avatar
Looks great! Not that you need to, but are you going to liteing hole the fuse at all or just leave it?
Feb 03, 2010, 04:51 AM
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Lightening Holes

I'm going to leave it. Likewise with the stringers, I could have used 1/8 but opted for 3/16 because I had 3/16 sticks.

The bottom will also be rounded off, but I left those for last so my bird can sit flat on the work bench.
Feb 03, 2010, 03:33 PM
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3/4 of the stringers are on and time for some landing gear and bottom formers and stringers
Feb 03, 2010, 04:06 PM
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Very cool! I like how that turned out. Going with the stock landing gear?
Feb 04, 2010, 09:03 AM
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Landing Gear

I am going to keep the stock landing gear for 2 reasons. First, I like the Old Timer look the wire gives the Auto Gyro and second, I think the resting angle of attack is pretty important for take off so if I went with an alternative gear, it would need to match the angle and height of the original. The wire gear will be permanently mounted and will require surgery should the need ever arise to replace it. Have a look at the pics.

About all that is left is to add some balsa at the fuse and hatch joints where they meet so I can sand to shape and ensure a good match between fuse and hatch.
Feb 04, 2010, 11:38 AM
jodini's Avatar
Looks great! Did you make the formers out of 1/8 ply?

So how about a cowl? YES?!!?!
Feb 04, 2010, 02:04 PM
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Lite ply for the first 4 formers and balsa after that. I was thinking of a sudo-scale radial engine to hang on the front in keeping with the autogyro theme
Feb 04, 2010, 05:03 PM
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Here you can see where I sanded some angles on the edges of the hatches to accept some balsa stock and I also added stock on the fuse at the hatches. I will then ensure the balsa is flat on the bottom of the hatches and sand the joint smooth. This will fair in the hatch to fuse joint
Feb 04, 2010, 05:05 PM
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Here you can see the joint sand smooth which blends the hatch and fuse perfectly and the hatches lifted out so you can see the finished hatches

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