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Old Feb 13, 2013, 03:09 PM
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Sweden, Stockholm
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Build Log
Dumas A6M3 Zero RC Conversion

This is my first thread in the micro-section, I hope it'll be a good place for my little build thread.

I just finished converting a free-flight J3C Cub for the balsa builders section free-flight to RC kitbash contest. If you're interested, the
build thread is here. Since I still need something to keep busy with during evenings, I've started on a little warbird. I already had a vintage Comet A26 Invader kit that I plan on building, but I think I need some more building experience before I tackle a twin engine plane which will need some hefty modifications for RC flight.

The plane in this thread will get it's eletronics from a scrapped UMX Beast (v1), except the engine will be swapped for a NTM motor that I've ordered from Hobbyking (failing to realize it's the chinese new year so I'm gonna have to wait a while until that ships..). I'm hoping that the motor will be more efficient, it's certainly going to be lighter with mount and propeller adapter included.

I've started looking at the fuselage but I decided I'll skip any major work on that until I know what the engine I'll use looks like. Instead I've focused on the main wing. The kit balsa is very light, therefore also quite soft so I'm fearing it'll be sensitive to hangar rash and things like clumsy handling, but at least it will be light without swapping out wood! The laser cut parts are so far a joy to work with. Everything fits together very nicely, and where it deviates a little bit from outlined in the plans, it's easy to adapt so far.

The kit includes parts and instructions for building either a Type 22 or a Type 32 (22 has rounded wing tips, 32 much straighter tips and no protruding antenna tower behind the cockpit). I'm making my wingtips a hybrid by using the shape from the Type 32 but making the wings slightly longer (see last picture).

The wings have a pretty thick profile, but the servos wouldn't fit inside the wing out where the ailerons are supposed to go so I'm leaning towards putting ailerons on carbon fiber torque rods, but if anyone has any ideas or tips on this, I'm all ears.

I'm considering making the whole plane without any access hatch and instead make the wing removeable in order to get to battery and pushrod adjustments etc. At least that's the plan for now.

I'm thinking that I'll increase the aileron size from what's outlined on the plans and thereby foresake some scale appearance in favor of control authority. I'm probably going to use both servos even though I could do it with one and some mechanics, but with two I can easily get electronic adjustability with my radio which is handy, flaperons is also a potential option this way which can be simply programed. It would be cool to use the potential spare servo for flaps, but I'll try to keep this bird simple so I dare to fly it regularly. I'm also not sure if flaps would do me any real good on a bird this small. I'll try to keep weight low (no landing gear) instead.
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Old Feb 13, 2013, 04:44 PM
MPP
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Danbury CT (DXR)
Joined Oct 2005
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Sounds cool, I was able to bury the aileron servos in the small micro Avenger i built. It is nice to have them in direct contact with the control horn. See if you have more room between R2 and R3 and even if they are recessed a little it could be a good solution. I have also set up two servos and torque rods with good results. I think you would be fine with the beast motor and 2S set up. Either way this is what makes these conversions fun as there is no right or wrong way to do them .

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Old Feb 13, 2013, 05:50 PM
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Medellín, Colombia
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great job! any space for retracts? lights?
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Old Feb 13, 2013, 08:39 PM
Gravity is a harsh mistress.
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United States, MI, Temperance
Joined Sep 2002
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Run some teflon or nylon/plastic tubing out to the ailerons and you can use a single servo mounted to move transversely using a fine guitar string as a flexible push rod.
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Old Feb 13, 2013, 09:45 PM
UMs & parkflyers... for now.
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Subscribed and watching with interest.
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Old Feb 13, 2013, 11:31 PM
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United States, MI, Ann Arbor
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I have a question for you guys- I just built a Dumas T-34 using the guts from a V-2 Beast, and I put the aleron servos in the wing with the control horns on the bottom as usual. I built it with no landing gear, and now that I am looking at the finished plane, it occured to me that one or both contol horns are probably going to get ripped off on the first landing. How do you guys protect your small linar servos on belly landers?
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Old Feb 14, 2013, 02:17 AM
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RFreak raises a concern I had as well, and a further reason I'll probably build the servos into the center section of the wing. A further reason to have them there, is to not have to extend the length of the cables, which I'd have to do to put them in line with the ailerons themselves. The cables would be long enough to go the distance without extension, but not long enough to allow for the required slack I'd need to use the whole wing as a hatch.

@MPP the Beast motor would certainly work. It's just on the heavy side with all the plastic it comes with. Besides, I've got a a still flying Beast which has a motor with a bad bearing, so I'll have a use for the motor, just not in this build! Oh, it'll still be 2S. I've got loads of appropriate 2S batteries and no 1S, so it's a matter of use what I have.
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Old Feb 14, 2013, 02:32 AM
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Quote:
Originally Posted by chulian1819 View Post
great job! any space for retracts? lights?
While doable, it's not actually something I'll do. I haven't found any good light kits with the appropriate size and I don't want to build my own at the moment. I'm kind of tempted to build micro retracts if I can't find any off the shelf that are small enough, but I'll try to build this particular plane with simplicity and low weight in mind primarily. Some day, I'll definitely build something small with retracts, just because it's awesome.
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Old Feb 14, 2013, 02:36 AM
ror
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suscribed too, my next project being a FW 190 D from blue bottle squadron, I have to wath this with interest.

Any chance you use a retract gear like this one ?

http://www.rcgroups.com/forums/showthread.php?t=1493173

bye
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Old Feb 14, 2013, 04:42 AM
UMs & parkflyers... for now.
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United States, VA, Herndon
Joined Apr 2012
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I've used covers, similar to those that come installed on the UMX Carbon Cub, to protect the linear servos. Once, I took plastic spoons and cut away part of the bowl. I also have thought of using parts of medicine bottles and suitable shaped pieces of clear molded packaging, recycled from purchased items.

HERE is a example of an commercial alternative.

HERE is a blog entry describing the use of foam egg crates... Omelets anyone?
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Old Feb 15, 2013, 09:45 PM
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I built the Dumas Corsair with the electronics from the V1 Beast, it was a quick little airplane. I used the scale outline for my ailerons which was a mistake. Your Zero should do very nicely with full span ailerons.

I'm also working on a Zero, though its slightly smaller than yours.
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Old Feb 16, 2013, 06:30 AM
ror
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@eclipe 7: what was the problem with your aileron ? not enought strenght ?
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Old Feb 28, 2013, 08:14 PM
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hows the zero going?
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Old Mar 01, 2013, 03:27 AM
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Quote:
Originally Posted by chulian1819 View Post
hows the zero going?
Very slowly. Other real-life-concerns have put a hold on the build. I've partially sheeted the wing, but it's still far from done so I haven't bothered posting any pictures yet.

This weekend won't give me much time to build either, but at least I finally (after 4 weeks) got the motor I ordered from hobbyking. Unfortunately, the prop-adapters I also ordered were crap so I think I'll need something else.
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Old Mar 01, 2013, 05:23 AM
UMs & parkflyers... for now.
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The next conversion contest is starting in the Balsa Builders forum, you should add this build in...
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