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Jan 16, 2020, 03:03 AM
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Molded CF 9 inch wingspan L Bird/ Citabria Stik


At the 2019 NEAT Fair I was very impressed with Gordon Johnsonís Molded CF Citabria Stik, and he very graciously offered to make me a set of parts to build one. I asked if he could make it smaller, and sent me the beautifully molded parts to build a 9 inch wingspan version!

My goal for the model was to make it as light as possible for a good living room flier. I was going to just use clear Mylar, but ended up painting it with Createx transparent green, white, black and blue paint.

I needed a lightweight gear drive, so I made one using a 300mg 3.2mm motor out of the mini Vapor servo mechanics, and a 90/12 Didel gear. The drive weighs only 600mg, and puts out 2.8 grams of thrust with a 500mg 10mAh LiPo cell. I also used a beautiful 3.2 inch foam prop that Ruslan sent me.

The model ended up weighing just under 3 grams RTF with the 10mAh cell.

This is a short video.

9 inch wingspan L Stik. (0 min 46 sec)


Joe.
Last edited by Joe Malinchak; Jan 16, 2020 at 03:29 AM.
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Jan 16, 2020, 09:41 AM
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Hi Joe, Great little airplane! I built 18 inch wing from molded carbon fiber similar to that your photo, but twice as big. I rebuilt an old balsa/stick plane from years ago. I replaced its balsa and saran wrap wing with the new mylar covered cf wing. This made it sort of a vintage hybrid test bed for my molded carbon fiber construction technique. Retained the balsa tail and split bamboo fuse with micro invent rx, home made actuators, and original 6mm gearbox. It flew outside ok in calm air. I am enjoying the challenges of this cf molding process. Happy flying, Al
Jan 16, 2020, 10:35 AM
in pursuit of low wing loading
Gordon Johnson's Avatar
Joe,
That came out really well. I like the green Military look. I also like the landing gear. The green fairings are a nice touch. And, it flies so well and so slow. I'll have to calculate the wing area and then loading from my CAD file at home. But, I'm sure the loading will be low. 2.99g is a very good weight for anything with a 9-inch span.

I was flying my larger version at our indoor session last Friday, and several people took turns with it. They all liked it. I think stick planes are pretty timeless. When they have nice graphics and color schemes that just makes them more fun.

Al, nice to hear you are progressing with CF molding.

Gordon
Jan 16, 2020, 11:21 AM
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Wow! That looks great Joe.

-Fritz
Last edited by fmhans; Jan 16, 2020 at 11:23 AM. Reason: Question answered above
Jan 16, 2020, 08:15 PM
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Amazing!
Jan 16, 2020, 08:49 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
The wing I molded for Joe has 28 square inches of area. That works out to 0.55 oz/sq.ft loading, roughly half the loading of a standard Vapor. So, the very low wing loading combined with the high camber airfoil results, as the video shows, in a very very slow flying plane.
Jan 16, 2020, 11:39 PM
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Gordon’s design actually met all of the goals I was trying to achieve with this model. I just wanted a nice slow flying plane for the living room. She is just a fun model to fly.

I put a few more timed flights on her, and I can get 4-5 minutes on the new 10mAh cell that Micro Flier Radio will be selling. microflierradio.com I checked the voltage after my 5 minute flight, and she was at 3.85, not bad. Nick sent me one these new cells last week to test in a model, and his timing was perfect! Thanks again Nick.

This is a photo showing the weight of the drive with the 10mAh cell, and the Rabbit receiver, 1.38 gram. I may replace the one that is on the plane to save another 200mg?
Last edited by Joe Malinchak; Jan 16, 2020 at 11:52 PM.
Jan 19, 2020, 03:50 PM
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RNAF's Avatar
This is so nice. Too kind of Gordon to get you a parts set. Also, I would never have guessed you could have that duration with a 10mA battery, just wow!

May I ask, could it be worthwhile to use the connector you have on the battery for a 4 or up to 6mm geared drive? I have a Deltang RX with a UMX connector and it’s heavy. On my peanut Mitsubishi Zero I also have a UMX connector as a Mini Vapor brick is installed and honestly it doesn’t have enough space. This connector is tinier and lighter?
Jan 20, 2020, 03:08 AM
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The time, and power that I am getting from the 10mAh cell surprised me as well. I did not measure the current draw on the 3.2mm drive, but it has to be low.

I have used these connectors before on a 6mm drive, and they worked fine. They weigh .14gr each. You can find some, smaller and lighter ones, I think Nick has them.

Joe.
Jan 20, 2020, 03:40 PM
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I added some CF bracing to the tail to give her more strength. I also made up a Brother Time decal just for fun!

Joe.
Jan 24, 2020, 12:13 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Joe,
I like the Brother Time decal on the tail. Same graphic as on your full size L4. I love it.

Gordon
Jan 30, 2020, 03:03 PM
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Vladimir88's Avatar
Joe,
Congratulations!
Beautiful work!
And the high achievement of low wing loading!

Vladimir.
Feb 01, 2020, 12:59 PM
Registered User
Hello Joe,

For your gearbox you use just one brass bearing ? can you describe please?

Thanks

charles
Feb 01, 2020, 08:45 PM
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AJWoods's Avatar
Nice Joe. Love the little leg fairings
Latest blog entry: Star Wars A-Wing Submarine
Feb 02, 2020, 08:06 AM
Registered User
Quite cute...

Mister Johnson, how does one qualify for such a set? I would like one.


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