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Old May 09, 2012, 05:53 PM
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The "Maggie"-Rubber-powered RC airplane

Hi folks.
I looked for the right category for the airplane I've just designed, but there really isn't a correct category for this. So I'm sticking it in the Park Flyers section, since that's about the closest category I can think of.

I'm into electric flight, and I especially love gliders. This all started in a discussion I was having with a friend of mine about alternative experiments for launching RC gliders. I decided to try out a rubber-powered RC plane. Now that servos and electronics are getting very light, it might be possible. Last weekend, I completed the hand-drawn plans for the following airplane, which I've roughly sketched here:



This is a 36 inch wingspan, rubber-powered (but electric-optional) RC plane with aileron, rudder, and elevator controls, and it has 194 square inches of wing area. The intention is to build something light, with a lot of wing area on a 14% average Clark-Y airfoil, but without the need to really strengthen the typical sailplane's high aspect ratio wing. Originally, I was planning on naming this the "Magpie" until I discovered that there were at least two other model airplanes named Magpie, one of which is sold by Mountain Models. So I will probably just end up calling this the "Maggie". It's a smaller version of a 6-ft flying boat design that I've also got, just to test out the aerodynamics.

The plans are going to the printers this Friday, and I'll make a couple of preliminary copies; one for me to build the prototype on, and then a couple of spares. I think I have enough building experience to pull this off.

Whether it actually ends up rubberized or not will depend on how light it will turn out once I've built it. If it's too heavy, I can always electrify it instead.

I'll post my progress here.
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Old May 29, 2012, 09:02 AM
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Good Luck.
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Old May 29, 2012, 05:36 PM
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Wow...I didn't think anyone was interested in my post.
Thank you.

A couple of things. I've built the wings and tail so far, and I'm sitting right at around 2.5 ounces built up to here. I think that if it were to remain free-flight, it could still be rubber. But by the time I add electronics, it'll be too heavy for rubber. Therefore, the prototype is going to be electrified.

I've also decided not to call it a Magpie or a Maggie. I think I've settled on a name, but still thinking about it. I'll post pics here soon.
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Old May 29, 2012, 06:02 PM
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Quote:
Originally Posted by builderdude View Post
Therefore, the prototype is going to be electrified.
oh no now it will have to go under electric plane talk

sorry, just messin'

good luck with the building. looking forward to the pics.
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Old May 31, 2012, 10:07 AM
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That is a very, very interesting idea, builderdude! I love to see someone doing something a bit different. I wish you the best of luck with your design.

By the way, I like the color scheme you chose for your rough sketch.
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Old May 31, 2012, 10:23 AM
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Thanks! The color scheme will change, however. Unfortunately, my original intention of naming this the Magpie won't work because there were two other airplanes named the Magpie. I was going to paint it to resemble a magpie anyway and just call it the "Maggie", which would have worked too, but I settled on another name that I like a little better. It will be called the "Phoenix". That is a fairly unique name for a model, which really surprises me. That being the case, it will be painted similar, but with hotter colors, red, orange, and white.

Here are some pics that I promised.

This is the entire wing, laid out like they're going to go. The lower wing panels (which I've laid out in the front), will attach to the fuselage underneath the upper wing panel. (See the sketch, above).



Here is a close-up of the upper wing panel and the lower wing panels. This part of the airplane forms a biplane wing...sort of.



Here is a close-up of the outer, elliptical wing panels. I've used laminated balsa to form the trailing edge. You can see the ailerons in this photo.




This picture shows the T-tail. The unique thing about this tail is the fin, which houses both tail servos. It looks like a lot of wood, but it's really not heavy. The entire T-tail weighs just half an ounce. (The wing weighs 1.9 ounces).



I am going to cover this in Microlite iron-on covering. It's white, but it's supposed to be able to accept paint. I'll be testing its paint adhesion qualities on this airplane.

There is no landing gear on this prototype, although, my plans included optional landing gear. With a 36 inch wingspan, it should be able to hand-toss just fine. I'll use a folding prop so that it can belly land. The main thing I'm after is keeping it as light as possible. I think I'm going to end up in the 10-14 oz range, ready-to-fly, which is too heavy for rubber (because of the added weight of electronics), but will do fine on a brushless outrunner. This should give it a stall speed of between 13.5 and 16 mph, estimated.
Wing area is 194 square inches.

If a person wanted to, they could build my plane as a rubber-powered free-flight, because without electronics, I think I could potentially hit 6 ounces flying weight. However, adding electronics tips the scale. I'm sure it'll fly great with an electric motor, but it would have been nice to test out the rubber motor RC idea. Maybe next time.
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Old Jun 04, 2012, 10:16 AM
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I made a lot of progress on the airplane this weekend. I've got some assembled pics to show. I've always liked how an airplane looks before you cover it and cover up all that woodwork.

A couple notes on this. First of all, it probably is light enough to be a rubber airplane. These assembled pics, as you see here, only weigh a total of 4.30 ounces so far. If this plane were to be built as a free flight, you'd only be looking at about another ounce and probably would come in finished at around 5.5 ounces; light enough for a rubber motor. But you start adding electronics and it will gain weight. Therefore, I decided not to waste all this effort on an annoying rubber motor, and decided to go with electric power instead. The battery box will be in the cockpit.

I don't have the plastic canopy yet. I've ordered it, but will have to wait until that gets in. In the meantime, I've got plenty of finish work left. I've got to mount the wing servos, run the wiring through the wings to the fuselage, and then I can probably start covering the wings and tail. I had to order some stuff, so I can't cover the fuselage yet. Hopefully, that stuff will come in this week. (That's the disadvantage to living in a small town).

This is going to get a small outrunner with a folding prop, and it will land on a skid on its belly, and be hand launched. If it comes in at 10 ounces flying weight, my predictions are that it will have a stall speed at a reasonable 13.5 mph. I'm shooting for coming in under 10 ounces, I hope.





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Old Jun 04, 2012, 11:38 AM
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Love your design and hopefully it'll fly, I put up a picture of a micro plane a good friend made for me and I presented it at the National Building Museum early this year and it won a first prize for unusual design. I love promoting things like these so people can get a good close look on where the RC world is going to. Love to do the same with yours if you would like to. Am very interested in it as it is usual in it's design. Happy flying.Would be interested in getting one built by you if you wish I would be most happy if you did. or I would settle for some plans or just the wood work done I can install the electrics and things. PM me when you can. Thanks
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Old Jun 04, 2012, 02:00 PM
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Hi Newbeflyer!

Thank you for your support. I will PM you, but let me just say that it will fly. You see, I built a 2/3rds scale glider out of solid balsa to test the design, and that flew great. At 6.5 ounces, with less wing and less airfoil, it flew a little faster than I'd like, but the purpose was to test it out. Based on that, I've made a few adjustments, and scaled it up to a 36" wingspan.

There is actually a larger flying boat version of this plane being planned too, but I wanted to test out my design and see how well it flew this way first. The flying boat is going to probably be in the neighborhood of a 6-ft wingspan. Baby steps first. I needed to test out my structural design concepts first, and it looks like it'll work.

Yes, I do plan on having the plans available, however, I'm going to have to make some corrections to the plans first. I've run into a couple of issues during the build process. So I'm weeding out all of the problems here. I may possibly be interested in building a second prototype, just to test out my plan changes and make sure everything's accurate. Let me think about it while I finish the build on this plane.

Once I've got everything solidified and it's a tested success, I'll have a better idea on everything. Thanks again!

And yes, I would be interested in some promotional help.
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Old Jun 04, 2012, 04:03 PM
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Look forward in watching out for you and your success on the plane. Your idea looks really well planned,if and when you get the plans all worked out, I can be a beta tester for you. I've done a few test with Jin Choe's micro Sopwith Triplane and it was a blast. Here's also another one of the,what I call "The Can Opener" plane the fuselage has a kinda can opener hook to it , it was built by Phil Fin in California and when he was finished with all the tweaks modifications he sent it off to me. It's a one of a kind thing and a real piece of work.Another of my works of art is this "slightly politically incorrect " Gee Bee I call it the Granville P-45 B. Look forward in being part of your build.
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Old Jun 04, 2012, 04:06 PM
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Here's the Gee Bee pictures
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Old Jun 04, 2012, 05:16 PM
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I love the P-45!!! That is really cool. This is my 4th design now. My first was an upscaled version of a small peanut scale glider from Flying Models magazine that I built as a powered plane. Second was a P-55 prototype. That one is flyable, and I'm confident it would fly, but it's far too fast for me. It's hanging up until I get my skills up to jet level. Then the 3rd is a Rocket-glider called the Kestrel, with a 49 inch swept wingspan. And this "Phoenix" is my 4th so far. I find that I'm beginning to prefer scratch building, because I can build anything I want.

Let me see if I can find pics of my other 3 that I mentioned above...

Here's my P-55:



Here is my Kestrel rocket glider:



And here's my Peregrine powered glider:

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Old Jun 05, 2012, 07:58 AM
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Those are fine planes you made there the P-55 is well done looks like you handled the rear motor type nicely as they are a little difficult to get the CoG right . Like you I think building from scratch is more rewording and the designs you can make is only limited by your imagination.
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Old Jun 05, 2012, 09:33 AM
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That P-55 came out heavy. I had to add 2 ounces of lead to the nose to get it to balance. It has an extremely powerful motor and 3-bladed prop, but with a stall speed of around 25 mph, it would really have to haul ars to take off. There's no way you could hand launch it. Bungie launching would work except for the fact that it'll get tangled up in the prop after the launch. I made the mistake of not having the nosewheel steerable, so unless you have a really long runway to get up to speed, ground launching could be a problem too.
So after scratching my head on how to launch and fly that thing, I finally just hung it up, because it does make a gorgeous display model.

Building light has been a challenge for me. That's why I'm proud of my latest plane, coming in at 4 ounces. I just installed all the servos, and it climbed to 4.8 ounces from the weight of the servos. Still pretty light. I'm expecting it to gain weight as I complete it. I just hope it comes in under 10 ounces total. This time, I made the nose longer, to try to counter the weight of the tail so that I don't have to add all that lead, like I had to do on the P-55.

And right now, the CG on my Phoenix without motor or battery installed, is right at the trailing edge of the wing. I'm hoping the motor, receiver and battery bring that up to the right spot without having to resort to lead ballast. I'm trying to learn from my mistakes.
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Old Jun 05, 2012, 09:59 AM
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One way I could launch the P-55 is if I drop it from another larger airplane. I've never thought of that before. That way, it'll get up to speed and I don't have any of the other launching problems I've mentioned. So one of these days, I'll have to build myself a plane big enough to haul a payload. I know there are planes like that out there, such as the Senior Telemaster, for example, but what's the fun in that? It'd be way more fun to build my own, even though I'll have to have a second pilot fly the P-55...at least until I can bring the mother ship down and land it.

And I know just the plane to build too. A C-47 flying boxcar would be a candidate, but it would have to be pretty large to haul this payload up.
Hmmm...something to think about.
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