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Old Mar 23, 2010, 09:00 PM
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Originally Posted by ajbaker View Post
Ah. Got it. I knew I was not understanding something. OK. Here is what happened. When you put the magnets back in, you started with the first magnet being opposite of the way it was before you took it apart. Let's say that the first magnet was N-S with the N(orth) part of the magnet next to the outside rim. Well, if you started with the S part of the magent next to the outside rim, the motor would run in reverse. There is no way to easily tell which pole is N or S. So, you could take all the magnets out. Or, just swap two of the wires. BTW-You will notice that I did not say "right" or "wrong" way on anything. That is because both ways of installing the magnets are correct (assuming that you went N-S then S-N then N-S..... when you installed the magnets). The only difference is that the motor runs the other way. Swap the leads when you get time and let us all know how it worked out.
AJ
I swapped the leads. Spins correct this time. Hooray.
BUT! Obviously there must be some slight build up on the epoxies and the magnets brush the armartures at a certain point. The bell ring has always been misaligned since new. Could always see a slight wobble. Only this time at certain positions it brushes. Therefore it jams when the motor is on. I took out the dremel ground down the friction parts. Now I can run it at half throttle but when I put it higher it seizes.

So I gave up. Installed the 2409-12 that I bought earlier as a back up. Works fine now.
Only problem is the CoG! It's moved back. The new motor is according to specifications 20gm heavier, maybe in reality it's more? Anyway, my previous setup with the stock motor was about the centre of the spar which was about 55mm from leading edge. Now it's 65mm. Right on the edge of the foam piece that covers the spar. How is the handling with the CoG that far back? Still stable enough? Or I'd better put some ballast in front? The battery (1800) is as far forward as it will go. I had to put some small fishing sinkers at the nose to get it back to the original CoG. However don't like unnecessary deadweight on the plane. Suggestions?
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Old Mar 23, 2010, 09:58 PM
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Originally Posted by victapilot View Post
The rudder wiggle seems to help get it moving. Mine is not stock, 6x6 prop, somewhere around 16000rpm
Have you found anyone that sells a 6x6 or are you just making them out of a 7x6?
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Old Mar 23, 2010, 10:08 PM
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Took some video with the CF 28-12 and the 6x5 prop on Sunday, was pretty windy, it handled it but it wasn't so much piloting as string-less kite flying.

AXN Floater 2nd Video (3 min 47 sec)
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Old Mar 23, 2010, 10:28 PM
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That's a nice video! Looks like you got quite high too. I got mine up to maybe 200 ft today, about all I dared.
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Old Mar 23, 2010, 10:36 PM
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Thanks. too bad youtube makes it look a lot darker than it was, might have to process it again and crank up the brightness.
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Old Mar 24, 2010, 01:07 AM
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Originally Posted by Flatbus View Post
So I gave up. Installed the 2409-12 that I bought earlier as a back up. Works fine now.
Only problem is the CoG! It's moved back. The new motor is according to specifications 20gm heavier, maybe in reality it's more? Anyway, my previous setup with the stock motor was about the centre of the spar which was about 55mm from leading edge. Now it's 65mm. Right on the edge of the foam piece that covers the spar. How is the handling with the CoG that far back? Still stable enough? Or I'd better put some ballast in front? The battery (1800) is as far forward as it will go. I had to put some small fishing sinkers at the nose to get it back to the original CoG. However don't like unnecessary deadweight on the plane. Suggestions?
I doubt it will fly very nicely like that. My CoG went back quite a bit with the 2409... Needs a flightmax 25c 2200mah all the way forward (I even squashed the foam inside the nose a little to get it even further forward) to fly nicely. Screwed the motor to the standard plastic mount, shimmed at the bottom enough so a 7" prop would clear the fuse by about 1/4".... This actually had the CoG about 50mm from the leading edge IIRC, which is near the front edge of the spar cover. Turnigy plush 30A esc in the fuse behind the rudder/elevator servos, and HK 2.4Ghz Rx sitting under the canopy, just below the latch magnet.


I found it flew superbly like this, all control surfaces trimmed level and shutting the motor off wouldn't pitch the nose up or down at all. With the slight downthrust it only pitches down a tiny going to WOT, over all it feels very well balanced.


You might just have to look at a 2200mah lipo, weighs about an ounce more... Although moving your ESC and Rx to under the canopy might help a little, then you might only need 5-10g of lead in the nose... which is still dead weight, but my CF has more hotglue than that in it any way
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Old Mar 24, 2010, 01:38 AM
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Thanks ninety six. I doubt I'll get a 2200 battery. I found the 1800 battery more than enough for me! I think I'll just get the 2216-06 motor from RCTimer. To replace the 2409-12. In the mean time I'll have to fly with lead in the nose.
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Old Mar 24, 2010, 02:47 AM
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Originally Posted by Flatbus View Post
I swapped the leads. Spins correct this time. Hooray.
BUT! Obviously there must be some slight build up on the epoxies and the magnets brush the armartures at a certain point. The bell ring has always been misaligned since new. Could always see a slight wobble. Only this time at certain positions it brushes. Therefore it jams when the motor is on. I took out the dremel ground down the friction parts. Now I can run it at half throttle but when I put it higher it seizes.

So I gave up. Installed the 2409-12 that I bought earlier as a back up. Works fine now.
Only problem is the CoG! It's moved back. The new motor is according to specifications 20gm heavier, maybe in reality it's more? Anyway, my previous setup with the stock motor was about the centre of the spar which was about 55mm from leading edge. Now it's 65mm. Right on the edge of the foam piece that covers the spar. How is the handling with the CoG that far back? Still stable enough? Or I'd better put some ballast in front? The battery (1800) is as far forward as it will go. I had to put some small fishing sinkers at the nose to get it back to the original CoG. However don't like unnecessary deadweight on the plane. Suggestions?
Slowly, take the weight out of the nose and do dive tests to see how it works. You should be fine at 65mm - BUT go slow - a tail heavy plane is too easy to crash. Personally, I fly mine at 76mm now because I like a slightly tail heavy plane. For aerobatics, I put the CG at 100m and use a gyro. You talk about fun. The plane does forward tumbles very easily. Crazy fun - but very, very sensitive and easy to crash.
AJ
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Old Mar 24, 2010, 02:52 AM
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Originally Posted by ajbaker View Post
Slowly, take the weight out of the nose and do dive tests to see how it works. You should be fine at 65mm - BUT go slow - a tail heavy plane is too easy to crash. Personally, I fly mine at 76mm now because I like a slightly tail heavy plane. For aerobatics, I put the CG at 100m and use a gyro. You talk about fun. The plane does forward tumbles very easily. Crazy fun - but very, very sensitive and easy to crash.
AJ
AJ, are using a gyro for your 76mm CoG?

What do you mean by dive test? As in throw and glide. Powerless? Or do you mean fly it, dive it and look for?

Thanks for your advice. Appreciate it
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Old Mar 24, 2010, 02:52 AM
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Originally Posted by Flatbus View Post
Thanks ninety six. I doubt I'll get a 2200 battery. I found the 1800 battery more than enough for me! I think I'll just get the 2216-06 motor from RCTimer. To replace the 2409-12. In the mean time I'll have to fly with lead in the nose.
Do you mean a 2212-6 from RCT?
AJ
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Old Mar 24, 2010, 03:00 AM
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Originally Posted by Flatbus View Post
AJ, are using a gyro for your 76mm CoG?

What do you mean by dive test? As in throw and glide. Powerless? Or do you mean fly it, dive it and look for?

Thanks for your advice. Appreciate it
No. I do not use a gyro for CG at 76mm.
Dive test -> Take the plane about 6 mistakes high and slowly drop throttle to get to a glide attitude and trim for level flight. Now, put the plane in a 45 degree dive and release the stick. The plane should slowly come back to level flight (with a very, very slight pitch up is OK). If the plane continued to dive, it is too tail heavy. If it quickly goes into a porpoise type movement, it is too nose heavy. I know this goes against any logical thinking. But, that is how airplanes work. The CG is just a starting point for planes - it determines the static CG. The dive test will determine where you need to have the Center of Lift - which is dynamic and more important than the CG. Don't try to visualize the above. It will make you nuts. Just do as outlined above and you will love how well your airplane flies. The basic rules still apply though towards wind tolerance - add more weight to the nose for more stability in the wind (or just for more stability) (which, of course, moves the CG forward). Flying a nose heavy plane carries it own risks. But, we will save that for another time.
AJ
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Old Mar 24, 2010, 03:29 AM
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Do you mean a 2212-6 from RCT?
AJ
Oops. Yes.
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Old Mar 24, 2010, 03:33 AM
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Originally Posted by ajbaker View Post
No. I do not use a gyro for CG at 76mm.
Dive test -> Take the plane about 6 mistakes high and slowly drop throttle to get to a glide attitude and trim for level flight. Now, put the plane in a 45 degree dive and release the stick. The plane should slowly come back to level flight (with a very, very slight pitch up is OK). If the plane continued to dive, it is too tail heavy. If it quickly goes into a porpoise type movement, it is too nose heavy. I know this goes against any logical thinking. But, that is how airplanes work. The CG is just a starting point for planes - it determines the static CG. The dive test will determine where you need to have the Center of Lift - which is dynamic and more important than the CG. Don't try to visualize the above. It will make you nuts. Just do as outlined above and you will love how well your airplane flies. The basic rules still apply though towards wind tolerance - add more weight to the nose for more stability in the wind (or just for more stability) (which, of course, moves the CG forward). Flying a nose heavy plane carries it own risks. But, we will save that for another time.
AJ
I think I follow you. It is to do with the the amount of lift or negative lift generated by the horizontal stabilizer to compensate for the moment arm between the CoG and CoL? Which of course would vary the speed of the aircraft? Something like that?

;-)

Thanks. Will try to get out and try that out soon.
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Old Mar 24, 2010, 01:57 PM
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Originally Posted by ajbaker View Post
No. I do not use a gyro for CG at 76mm.
Dive test -> Take the plane about 6 mistakes high and slowly drop throttle to get to a glide attitude and trim for level flight. Now, put the plane in a 45 degree dive and release the stick. The plane should slowly come back to level flight (with a very, very slight pitch up is OK). If the plane continued to dive, it is too tail heavy. If it quickly goes into a porpoise type movement, it is too nose heavy. I know this goes against any logical thinking. But, that is how airplanes work. The CG is just a starting point for planes - it determines the static CG. The dive test will determine where you need to have the Center of Lift - which is dynamic and more important than the CG. Don't try to visualize the above. It will make you nuts. Just do as outlined above and you will love how well your airplane flies. The basic rules still apply though towards wind tolerance - add more weight to the nose for more stability in the wind (or just for more stability) (which, of course, moves the CG forward). Flying a nose heavy plane carries it own risks. But, we will save that for another time.
AJ

A nose heavy plane billowing up in a dive test is logical taking into consideration that to first achieve level flight some up elevator trim was probably introduced. This trim in the dive test pushes the tail down.
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Old Mar 24, 2010, 02:50 PM
Just thumbing through...
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United States, SC, Simpsonville
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Originally Posted by tankd0g View Post
Have you found anyone that sells a 6x6 or are you just making them out of a 7x6?
It's a cut down MA 8x6. I mounted it in a drill to sand down to final size, and checked balance on a Great Planes balancer. It was almost perfect, but I did fine tune by hand.

I like 3 blade for AP, no vibration even at max power. On the down side it cavitates just thrashes the air, if the airspeed is not high enough. Pulls 20 amps static.
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