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Old Feb 11, 2015, 10:33 PM
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Scott C's Avatar
United States, GA, Peachtree City
Joined Aug 2000
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RCM "My oh My" plan #795

I've decided to tackle my first glow to eletric conversion with a plans built RCM's "My oh My" parasol sport plane. I will be cheating a bit with a short kit from Lazer Works http://lazer-works.com/rcm.html. First order will be to modify the nose to accept a .10 class motor and a battery tray. The wings will be built flat as Kansas with individual servos commanding the ailerons. I am lucky to have Aircarft Spruce http://www.aircraftspruce.com located about 10 minutes away and will have them to mill custom one piece spruce spars. The endgame is to have a lightly wing loaded aircraft that will fly realistically on the wing. I'm not going to guarantee that this will be the fastest build, but should be both challenging and rewarding.
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Old Feb 12, 2015, 07:21 PM
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United States, OK, Moore
Joined Jan 2006
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Sorta like a Q-Tee on steroids. Should be an interesting project!
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Old Feb 14, 2015, 01:38 AM
UAS Pilot/Tech Instructor
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United States, CA, San Diego
Joined Apr 2000
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Would look 10 times better if you slanted the top block/hatch down like the original. That flat top hatch is not very stylish but in any case, this plane has been sitting on my mind as well for a Sunday afternoon flyer and is perfect for E-conversion. I'd forgot all about Lazerworks and didn't realize they had a short kit. Hmm.....

Will definitely be watching this build.

Mike
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Old Feb 14, 2015, 06:03 AM
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Joined Nov 2013
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My-oh-my

I built the MY-OH-MY from the plans about 35 years ago. It was one of many planes that I built while our boys were growing up. It flew with an OS Max 25 I think, on floats and skies. I never did learn to fly. The boys would let me fly the my-oh-my when it was airborne . Now at age72 I learned to fly last summer and have assembled some foam planes, all electric. I was searching for plans for the my-oh-my and almost gave up . I will build this aircraft and power it with electrics.
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Old Feb 14, 2015, 07:29 AM
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United States, GA, Peachtree City
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I agree that the hatch should have some rake to it, thought it might be easier to build a little linear. Anyhow, I went by Aircraft Spruce and placed an order for 25' of 3/16" square and 6' of 3/16" x 1/2" spruce. Even though I over ordered a bit, It seems like a lot of spruce. I believe by building the wings flat with carry through spars, I should be able to eliminate the need of the fiberglass center section. I can't quite wrap my mind around this design, it appears to be light and heavy at the same glance. I am on an IPad now and will try to post the plans and article later.

Cessna180 that is a great looking plane. Do you recall the finished weight?
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Old Feb 14, 2015, 08:28 AM
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Here are the plans and my modified nose.
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Old Feb 14, 2015, 09:41 AM
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my-oh-my

Unfortunately I do not recall the weight. My guess would be 3.5 to 4 lbs. gross. You mention building the wing straight. I would not. Remember to build in the washout and also the dihedral is a must because it is a 3 channel aircraft. Unless you are going to build in ailerons I would still build in some dihedral (1 inch each wing) and also the washout. I would still glass the center section for strength. Perhaps substitute the lite ply with 3/23 balsa may save some weight Even at 4 lbs . wing loading would be only 16.46 oz/sq.ft. At this the wing loading (gross 4 lbs.) that I would try to achieve and it would make a great flyer. I would use a motor between 300-400 watt and 4 cell. As I recall our boys flew the heck out of the aircraft as it was the easiest one to fly out of many many that I built.
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Old Feb 14, 2015, 10:17 AM
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United States, GA, Peachtree City
Joined Aug 2000
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Here is my Sr Cutie, you might say it was a catalyst for my current project. It was originally like the My-oh-My 3 channel. However I built the wing straight with 0 deg dihedral. As it can be made out in the photo, I tapered the ailerons which probably emulates washout -- especially with flapperons down. It is a great flyer.
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Old Feb 14, 2015, 08:04 PM
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United States, CA, San Diego
Joined Apr 2000
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Hey Scott, I like the top block rake. I know its more work but if you use a solid block you can carve out the inside to make a cavity old school style and save a little weight....

Flaperons actually add wash-in which is not always desired. That's why you almost never see them on full scale planes. Reflexing the ailerons (i.e., trimming the ailerons up a tiny bit) simulates wash-out. That's why using alot of flaperon travel is not recommended as it can really raise the stall speed out at the wing tip. Your tapering the Ailerons mitigated the effect as there is less surface travel out there.

Its like you are reading my mind about the stated weight of this plane. I think its all the "Lite"-ply) but like Cessna says, it still has a light wing loading and will fly great. If your going for the low end of the power scale I would definitely cut in the lightning holes as suggested on the plans. I have also thought of replacing the sides with a 1/8th balsa (no lighting holes) instead with 1/64 or 1/32 ply fuse doublers out to the cockpit. I would think for a lower power electric this would be okay but it looks like your going for some aerobatics, plus it sounds like you already have a kit with the lite-ply parts so I would just use them.

EDIT: Speak of the devil, this guy just started a thread about his E-conversion, http://www.rcgroups.com/forums/showthread.php?t=2347388 which is about the same size and weight of the My-O-My. He ended up replacing the lite-ply with balsa. Having said that, if you do replace with balsa you might want to consider at least sheeting the bottom with 1/16 balsa cross grain instead of the just the square pieces of stick holding the sides apart as shown.

Fun Stuff,
Mike
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Last edited by CryHavoc; Feb 14, 2015 at 08:25 PM.
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Old Feb 15, 2015, 08:26 AM
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United States, GA, Peachtree City
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My short-kit is enroute from Texas. I like the idea that the fuselage is fairly simple with no doublers. My short term plan is to increase the size of the lightening holes in the aft fuselage. Also, I will give the wing ribs the Swiss cheese treatment as well. These Hershey bar constant cord wings are fairly forgiving. Here is a short video of my last airplane demonstrating the use of flaperons.

SwitchBack Sr (1 min 19 sec)
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Old Feb 17, 2015, 12:20 AM
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United States, CA, San Diego
Joined Apr 2000
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Quote:
Originally Posted by Scott C View Post
My short-kit is enroute from Texas. I like the idea that the fuselage is fairly simple with no doublers. My short term plan is to increase the size of the lightening holes in the aft fuselage. Also, I will give the wing ribs the Swiss cheese treatment as well. These Hershey bar constant cord wings are fairly forgiving. Here is a short video of my last airplane demonstrating the use of flaperons.
Hey Scott,

Same here, I like simple. Don't be surprised at how little is actually saved Swiss cheesing the ribs. I did it a couple of times until I realized how much time and work it is to save about an ounce. Plus all the headache trying to repair the fragile damn things while trying to get the wing assembled. Make sure you take a few pics before the covering because they make the wing structure look awesome once its all done.

Mike
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Old Feb 18, 2015, 08:59 PM
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United States, GA, Peachtree City
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Well, it is starting to come together. My short-kit arrived, went by Aircraft Spruce and picked up my custom spars. Last night on the way back from a mountain holiday, I stopped by Hobbytown USA and found some leading and trailing edge stock. The short kit appears to be well done; however I think there might have been two slightly different version of this aircraft. The lighting holes are different (better), bolt mount saddles parts are included, and the ribs are slotted for 3/16 x 1/4 instead of 3/16 square spars. The change in spar sizes concerns me a little, but I think I will push through and use the 3/16 square since I already have had them cut. I will add 1/16 shims to get a good fit.

Here is a link to the owner of Lazer Works' My-oh-My.

http://lazer-works.com/gallery/main.php?g2_itemId=208


Cheers
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Last edited by Scott C; Feb 18, 2015 at 09:28 PM.
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Old Feb 21, 2015, 06:00 PM
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Scott C's Avatar
United States, GA, Peachtree City
Joined Aug 2000
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Making good use of my old college drafting kit by giving the new nose a pleasant look. The plans had a nose down thrust line of 6 to 7 degrees, I plan to go with about five degrees nose down.
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Old Feb 22, 2015, 04:07 AM
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United States, CA, San Diego
Joined Apr 2000
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The kit looks good.

I'm trying to decide if I like the bolt on wing hold down as I kinda like the old school vibe of this kit. But it sure is cool it gives you an option.

Mike
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Old Feb 23, 2015, 09:30 AM
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United States, NC, Burlington
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looking good.
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