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Old Jul 31, 2012, 07:03 AM
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United States, SC, Charleston
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If you want stability add one of these
Plan on putting one on my FC with the thumb camera onboard.
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Old Jul 31, 2012, 08:31 AM
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mixer421's Avatar
United Kingdom, England, Kent
Joined Aug 2007
508 Posts
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Originally Posted by MRN View Post
Well, I've got the vibration problem the others are talking about. At about 3/4 throttle I get a sudden vilolent vibration. It is so bad that it has split the fusalege down the glue joint two or three times.
I've tried different props, collets, motors, and ESC's. I've beefed up the motor mounts. Same results.
I think the problem is that the motors, an Eflite Power 15 and an AXI about the same size, are just too big for the plane. Tomorrow I'll buy a smaller motor and try it.

Any comments? What size motors are you guys using?

To the guys talking about aileron effectiveness, are you using "aileron differential" as the manual recommends? Thats about twice as much up movement as down movement. Doing this will help prevent "adverse yaw" and the plane will turn much smoother.
I agree with some of the other guys about learning to use the rudder properly. It's kind of cheating using a radio mix to co-ordinate rudder with ailerons, but it really flys nice that way.

Mike
It does seem that most people who suffer vibration problems are using motors that are far bigger than the plane was designed for. I'm quite happy with my little 1100kv 3530 turning a 12 X 6 on 2 cells. It's light, has adequate performance and 15min flight times.
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Old Jul 31, 2012, 11:17 AM
Bruno, GOOD DOG
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United States, IA, Grinnell
Joined Aug 2007
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Quote:
Originally Posted by Early View Post
If you want stability add one of these
Plan on putting one on my FC with the thumb camera onboard.
I have one of those coming as well, and I think it will go in my FUNCUB. But I can't decide where to put it. It works best to mount them on the CG, but I am not sure where to put it. I am thinking of digging a whole in the foam in the top of the fuse right under the wing. I have 4 of these things flying now (different brand of course) in other planes and they work REALLY well.
Look at this thread, if you haven't seen it yet.
http://www.rcgroups.com/forums/showthread.php?t=1614811
Rn
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Old Jul 31, 2012, 12:56 PM
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Originally Posted by A Rdnek View Post
I have one of those coming as well, and I think it will go in my FUNCUB. But I can't decide where to put it. It works best to mount them on the CG, but I am not sure where to put it. I am thinking of digging a whole in the foam in the top of the fuse right under the wing. I have 4 of these things flying now (different brand of course) in other planes and they work REALLY well.
Look at this thread, if you haven't seen it yet.
http://www.rcgroups.com/forums/showthread.php?t=1614811
Rn
Good point, didn't think too much about placement.
I'm guessing we probably won't see one for a month or so though due to BO.
And don't you need servo extensions to go with these units?
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Old Jul 31, 2012, 02:39 PM
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United States, NY, New York
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Quote:
Originally Posted by mixer421 View Post
It does seem that most people who suffer vibration problems are using motors that are far bigger than the plane was designed for. I'm quite happy with my little 1100kv 3530 turning a 12 X 6 on 2 cells. It's light, has adequate performance and 15min flight times.
your probably right im running apower 10 1100kv @ 500 watts on a 12x5 prop pulling 40+ amps . it fall within range of the recomended specs .
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Old Jul 31, 2012, 08:44 PM
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Hi Guys, Flew the FC on floats again tonite, and on take off the bracket on the rear floats pulled loose from the float, so I patched it up with black tape, took off and I must admit not the softest landing, but the rear float bracket came loose from the airframe! anybody have suggestions!
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Old Jul 31, 2012, 08:58 PM
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ps, I think I used CA
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Old Jul 31, 2012, 09:46 PM
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United States, GA, Atlanta
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Quote:
Originally Posted by burnzy View Post
Hi Guys, Flew the FC on floats again tonite, and on take off the bracket on the rear floats pulled loose from the float, so I patched it up with black tape, took off and I must admit not the softest landing, but the rear float bracket came loose from the airframe! anybody have suggestions!
Said it before a few posts or pages ago. Make sure you use regular ca, not foam safe. Before gluing, I use a pin to poke holes in the foam, and rough up the surface of the plastic up with 80 grit sandpaper. My theory is that it gives the glue more surface area to hold onto. Lots of less than perfect landings on mine and it still holds strong. . Anywhere I have a plastic on foam joint that is critical, this is what I usually do.
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Old Jul 31, 2012, 10:32 PM
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M.Gonyea, you were right, the CG is at 50mm. The wing chord is ~210mm, so 25% (also the location of the spar) is where I did the quick check for CG. I had just seen more rearward CG in 3D type planes (or planes not like a high wing trainer).

Thanks for the advice about differential. I'll give it a try this weekend. do use rudder and I have 25% aileron to rudder mixing already, but it probably a moot point as it is out of balance. I had actually forgotten about differential, as I rarely fly high wing planes. I've had a Hyperion .25 Cub and PZ Cub in the past though, and they were about 25% IIRC.

I'm using a EFlight Power 10 with a 12x6 and 2200 3S, which doesn't seem out of line for a plane like this. The prop is balanced very well, and there is no hint of vibration until 3/4 throttle. I had read the motor might need to be balanced, but that doesn't make sense; it shouldn't induce an airframe destroying resonance. I had pulled this motor, prop and collet from another plane that had been working fine for 8 months until I put them on this plane. I'll try a different prop and some epoxy on the motor mount, then stiffening on the nose.

Thanks for everyone's help!
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Old Jul 31, 2012, 10:47 PM
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Now that I think about it, with the vibration I experienced, the motor mount might be loose in the fuselage now. I'll put a layer of fiberglass and epoxy over the existing motor mount installation behind the firewall.

Edit: I should mention it had no vibration for 8 or so flights, no prop strike whatsoever. Full power passes had no hint of vibration. It was smoother and quieter than most of my planes.
I knew it was a motor mount for a power 10 that was connected to foam, so I glued up the mounts with thick CA, then filled the mount/fuse joining spots with medium CA and let everything set for more than a week. Oh well.
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Last edited by eagle777; Jul 31, 2012 at 11:30 PM.
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Old Aug 01, 2012, 05:36 AM
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I have no vibration issues with my huge engine. Needed to cut out foam to fit it. 900W peak with 13x6,5 prop. I just used regular super glue with activator on the whole plane and an aluminium motor mount. Probably 40+ flights, no vibrations.
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Old Aug 01, 2012, 10:30 AM
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United States, MI, Royal Oak
Joined Nov 2005
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Question guys, I have the stock recommended himax 840kv motor with the recommended 13x4 APC prop and I get very good performance with it. I would like to put a 3-bladed prop on, but have no idea how to figure out what would be equivalent to an APC 13x4.

What would you guys recommend? Thanks in advance for any advice.

Jordan
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Old Aug 01, 2012, 11:14 AM
GLM
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Check Six!
Joined Oct 2003
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Fun Cub Floor/Stiffener Kit

Hi All,

I finished the FunCub Floor/Stiffener Kit for this wonderful aircraft. It took a couple of rounds...

Here is the description from the webpage:

The FunCub Floor/Stiffener Kit is a retrofit installation. It will assemble in a completed aircraft like a ship in a bottle. It will also install in a new build. It weighs 1.5 ounces

It was the design intent to dampen the torsional effect and vibration some pilots are experiencing that the motor puts on the front end of the FunCub. I recommend Foam-Tac or Epoxy for the installation glue.

I also reccommend drilling and tapping the lands for the incidence adjusting screws and installing 4 additional screws and using a washer between the motor mount and the mounting rails to achieve the correct incidence for your motor and prop combination.

The parts will be numbered 1-7. #1 being the floor - I recommend dry fitting the parts together out side the aircraft to get a feel of what it will look like installed. Then dry fit the parts inside the aircraft to see how everything fits together then removing them and going ahead with the final install with glue.


Here is a link if you want to take a look!

http://www.morganmill.com/RC/FunCub_Parts.html

Scroll down on the page - there's lots of pictures and some instructions on installation. Hopefully they are clear - who knows - it was late and sometimes things look crystal clear and the next day you look at them and wonder WTH?

And some pictures here.

Cheers!

Gary
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Last edited by GLM; Aug 01, 2012 at 12:33 PM.
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Old Aug 01, 2012, 12:07 PM
This is BAT country!
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United States, MI, Ovid
Joined Nov 2003
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Looks pretty cool!
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Old Aug 01, 2012, 12:09 PM
This is BAT country!
Gonzo 1971's Avatar
United States, MI, Ovid
Joined Nov 2003
618 Posts
Anyone used goop on elapor? Thinking tbat would work great on my broken motor rails.
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