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Megatech A7 conversion.

Old 01-03-2009, 04:31 AM
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aramsdell
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Default Megatech A7 conversion.

Anyone who has put a real radio and motor in one please chime in.
I put first real flights on my conversion today. 4 channels. Berg 4. 2.5g servos on rudder and elev. 3.5 g on ailerons. Turnigy 12mm and EDF50. 3 blade impeller. Performance is just a little better than the old stock setup. Endurance is so much longer. Climb is anemic. I think the 12mm motor could be 1/2 the problem. Theother is probably it need a smooth thrust tube behing the edf.
Ailerons are super effective. Rudder works quite well and ailerons aren't NEEDED but desired. The elevator is my biggest Coup d'e-tat. Iused a piece of carbon rod to bridge across the tail and mounted a piece of depron in the exhaust stream on it for vectored thrust. If I had more thrust it would do high alpha.

Any suggestions would be nice.
I managed to build and balance at same time with 350 mah 3 cell sitting in the same spot as the original bat, under the canopy. No balast was used while harming this plane.
Motor is drawing about 3 to 3.5 amps. That is max cap on the 10c bat in it.

Those who have done a conversion, Fegaio 12mm motor What amp draw and what impeller?

Need more speed.

Low speed handling was really good but had a nose high sharp stall break.
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Old 01-03-2009, 04:42 AM
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Bill G
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Originally Posted by aramsdell View Post
Anyone who has put a real radio and motor in one please chime in.
I put first real flights on my conversion today. 4 channels. Berg 4. 2.5g servos on rudder and elev. 3.5 g on ailerons. Turnigy 12mm and EDF50. 3 blade impeller. Performance is just a little better than the old stock setup. Endurance is so much longer. Climb is anemic. I think the 12mm motor could be 1/2 the problem. Theother is probably it need a smooth thrust tube behing the edf.
Ailerons are super effective. Rudder works quite well and ailerons aren't NEEDED but desired. The elevator is my biggest Coup d'e-tat. Iused a piece of carbon rod to bridge across the tail and mounted a piece of depron in the exhaust stream on it for vectored thrust. If I had more thrust it would do high alpha.

Any suggestions would be nice.
I managed to build and balance at same time with 350 mah 3 cell sitting in the same spot as the original bat, under the canopy. No balast was used while harming this plane.
Motor is drawing about 3 to 3.5 amps. That is max cap on the 10c bat in it.

Those who have done a conversion, Fegaio 12mm motor What amp draw and what impeller?

Need more speed.

Low speed handling was really good but had a nose high sharp stall break.
There's a good chance your batt is not quite up to the setup. Also, I don't think the Turnigy has the high kv ratings that Feigao has. I've actually gotten reasonable performance from the 4100kv Feigao in the EDF50, but it's not the same thing as the 5866kv Feigao. With your presumably lower kv, you probably will get the best performance with the 6 blade rotor also.

While the Feigaos (or most all 12mm motors) are ran over spec in the 40 and 40mm fans, they still hold up reasonably well with a heatsink. The 5300kv and 5866kv Feigaos will draw up to 6A in the EDF50 fans. I've found the TP 3s-480 to be the lightest battery capable of reaching full power with those setups.

The exit diameter of that plane may be a bit large for the EDF50 also. Don't know, as a buddy had one, but it was a while ago. The stock ducted prop setup may very well use a larger exit dia than the EDF50.
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Old 01-03-2009, 04:51 AM
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aramsdell
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She was beat before the operation.

I built a depron ring-2 actually to hold the fan and seal the larger inside hole. The area behind the fan is a bit larger than the back of the fan and may be robbing some power. Bench test of the fan indicated a ounce or more thrust than when inserted in the fuse.
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Old 01-04-2009, 01:14 AM
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Bill G
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Off top of head the outlet looks large. Something in the neighborhood of 45mm diameter is where you want to be. Looks like you have a real servo in there. I remember repairing the stock actuator setup for a buddy that had one. A blade of grass in the mechanism would be enough to hang it up.
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Old 01-04-2009, 04:23 AM
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2 Servos (2.5 g )are under the wing. Only the horns show. The only thing in the airflow, inside the fuse, is the little tab on the elevator joiner that vectors elevator control.The servos actually are in a cavity above the air duct. I am going to try a Fegaio 12 mm and a TP 3s 480 as well as building a plastic thrust tube to insert into the tail. The exhaust tube is not even and smooth so prob. a lot of turbulence.
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