Portable indoor plane - RC Groups
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Dec 28, 2012, 08:08 PM
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slebetman's Avatar
Build Log

Portable indoor plane

Well, here I go again starting another build before finishing the last one (two actually). This one I couldn't resist.

The idea actually started when I saw a video on youtube several months back about a rubber powered plane that can be dismantled and stored in a small box. It's called matchbox planes or something (they were referring to big match boxes - something that doesn't exist where I live). Anyway, bought myself a pair of earphones recently and it was packaged in a very nice acrylic box. So obviously I had to build a plane that would fit in the box.

The box is roughly 5 inches by 6 cm. Yeah, I know, mixed units but if I were to stick to either inches or cm I'd end up with odd decimals and weird fractions. So, if we assume a two part wing that gives us roughly 10 inches of wing span - good size for an indoor plane.

In order to maximize surface area I built everything square. No angles (apart from the rudder), no rounded corners just simple straight lines. As such, there wasn't much of a plan. I just drew two parallel lines 5 inches apart and drew every part in between the lines.

It's mostly done apart from the prop. I'm hoping to finish the prop today so that I can do some trimming flights tonight.

The weight at the moment is around 1.6g including the clay nose weight. I assume the weight will end up roughly the same with the prop.

This is what I ended up with:

I've started another build and documented the build process. I've also drawn up plans for this plane. The actual build log starts here: https://www.rcgroups.com/forums/show...3#post24048561

Last edited by slebetman; Feb 12, 2013 at 11:48 AM. Reason: Update build status
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Dec 28, 2012, 10:10 PM
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That's pretty cool!

I like the way you designed the plane for the requirements of good practical transport. I more or less build my RC gliders the same way with the goal of always disassembling them and putting everything in and on a medium sized backpack so I can ride my bike to the places I go fly. I recently got into making small catapult gliders and have a system for bike transport for them as well.

Hats off to you for the most compact transport container and transportable model plane I've seen yet.

Adios - Paul
Dec 28, 2012, 11:42 PM
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slebetman's Avatar
Thanks Paul.

I've just finished building the prop. It's made from a thin/cheap plastic cup with a balsa hub. The shaft and hook is made from number 2 guitar string - just like all the other metal parts of the plane.

With the prop it's now 1.4g - even lighter than I thought it would be. This is actually the lightest plane in my fleet at the moment.

Tried several test flight in my living room. With a 9.5 inch loop of 040 rubber it climbs even on as little as 100 winds.
Dec 29, 2012, 07:42 AM
You know nothing....
Stuart A's Avatar
Neat.This explains the delay in your other build
Dec 29, 2012, 01:35 PM
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jrs_123's Avatar
I remember a magazine article years ago (perhaps in Model Builder?) where a guy had ready to assemble and fly models in a matchbox!
Dec 30, 2012, 12:22 PM
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slebetman's Avatar
Finally got it trimmed to fly in circles. Rudder was next to useless - yes it would induce the turn but as the rubber was winding down and the prop slows down it would drastically lose effectiveness causing the plane to fly straighter. Couldn't find a rudder+thrustline combination that would work throughout the flight evelope.

The real solution was to tilt either the horizontal stabilizer or the wing. Should have done that in the first place but thought I could trim it with rudder alone. At the hall I simply twisted the tail boom to induce a tilt of the h-stab. When I got home I reglued the dihedral brace to create a permanent wing tilt. I also took the opportunity to induce wash out on the inner (port) wing by tilting the rear brace slightly more. The port wing is now almost parallel to the h-stab.

Here's a video of it flying in my living room:

Portable rubber powered plane (0 min 33 sec)

Sorry for the fuzzy vid but my phone couldn't quite focus on it.
Jan 04, 2013, 09:24 PM
Registered User

That is cool!

Hey, I just watched the video of your plane, that's pretty cool. When I think of "indoor freeflight" I think of school gymnasiums and other "large" empty spaces. I never would have guessed that when you previously mentioned test flying in your living room that you had it trimmed to actually 'circle' in your living room!

That's pretty cool stuff - Paul
Jan 05, 2013, 07:25 AM
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slebetman's Avatar
Originally Posted by Pauliwog
Hey, I just watched the video of your plane, that's pretty cool. When I think of "indoor freeflight" I think of school gymnasiums and other "large" empty spaces. I never would have guessed that when you previously mentioned test flying in your living room that you had it trimmed to actually 'circle' in your living room!

That's pretty cool stuff - Paul
This is actually my second plane that I got to circle my living room (20ft wide). The first only managed at most 2 circles in10 seconds. With this I can consistently get 5+ circles and 30 seconds average flight in my living room. Will be flying it at a mall after business hours tonight. It's where a bunch of us meet on weekends.
Jan 05, 2013, 03:14 PM
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slebetman's Avatar
Here's a video of it flying at the mall. My best time today was 2:45 but I didn't record that flight on video

Portable indoor plane (1 min 59 sec)
Jan 10, 2013, 09:42 PM
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That's Cool!

Thanks for posting that last video, that's pretty impressive, it climbs really well!

Adios - Paul
Jan 10, 2013, 10:35 PM
B for Bruce
BMatthews's Avatar
A really sweet flying project. It's especially nice that it's so portable thanks to its own case and all.

You may want to look at the Parlour Mite models for inspiration to guide you towards a Mk II breakdown version.
Jan 11, 2013, 09:16 AM
Registered User
Quite impressive sir, damn fine job.

And thanks for the inspiring videos
Jan 13, 2013, 03:32 AM
Registered User
That's a nice flying little plane. I'm really impressed with how small a box it stows in.

I've flown Mini Sticks in a much smaller living room, but 30 seconds doesn't seem like very long after flying them in a larger space. Limit is eventually hitting the wall.

Sounds like you may have too much climb. If you go to a somewhat larger, built up balsa prop, I suspect you'll get longer times. Also if you make a bigger stab, and, if you have room, a longer tail boom, you can use a light prop and let the c.g. move back.

I have a 22 inch twin pusher that fits in the box a computer keyboard came in, with a small extension, but that's nothing compared with what you've done here.

Maybe you can collaborate with someone who's makes ships in bottles.
Jan 13, 2013, 04:09 AM
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slebetman's Avatar
The limit is the size of the box: 5 inches by 60 mm. So the prop has to be 5 inches max. I've flown it with a 6 inch prop and it does fly smoother but the prop doesn't fit in the box.

And it's not just the prop. Everything is designed for the 5 inches max to fit the box - the motor stick, the tail boom, each wing half and the stab.

Another limitation is actually a design mistake. I didn't provide enough clearance for between the rubber and the motor stick and as the rubber unwinds it tends to bunch up and bind on the motor stick. I've modified the motor stick a bit by gluing a piece of balsa on top of it so that I can carve out the bottom for clearance. Unfortunately I've got the flu this weekend and can't test it properly. We'll see how she flies next week. I'm convinced that I can get over 3 minutes when she's all trimmed out.
Jan 16, 2013, 02:00 AM
Registered User
LOTS of people with the flu around here as well. Yuck.

There is an indoor style of prop where the hub is a tissue tube. This is usually for pitch adjustment, but you could take one blade off easily.

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