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Old Oct 13, 2014, 03:03 PM
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Help!
Help me select a motor and prop for 30 year old Telemaster

Hey guys. I am new to electric planes. I am building a couple this fall.

I have a 30 year old Telemaster 66" 4 channel plane, that I built with my grandpa when I was a kid. It flew once with the .40 K&B engine way back then, and sat broken for many years. I have recently removed the engine, repaired and recovered the plane, and it is in great shape! I want to convert it to electric motor for obivous reasons, but I don't know what motor would appropriate.

The plane originally used a 10x6 prop, if I recall correctly. I also have many 3S 2200mah Lipo batteries from my heli's, that I would like to use, if I can. Maybe run two batteries?

Can someone recommend a budget brushless motor and prop for my Telemaster? I am hoping to find something at HobbyKing, since I need to make an order from there anyway. It weighs about 4.25 lbs, without a motor/battery/esc, but with servos. It is a high wing 4 channel trainer type plane.

Thanks in advance!
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Old Oct 14, 2014, 01:01 PM
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nobody? I think I can manage selecting a good motor now, but still have no idea what kind of mount. Ugh. Maybe I will just go with a nitro engine again.
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Old Oct 14, 2014, 02:49 PM
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Check this post
http://www.rcgroups.com/forums/showp...8&postcount=11
for suggestions on how to size the components.
As for brands,
I have use SK3 motors from HK and generally I am happy with them.
For ESCs, I use the Red Brick. They are cheap BUT they need to be inspected before using them, which involves cutting the wrap and making sure the
aluminum plate on the back size (that is, the side opposite to the FETs) does not
touch the + and - wires
http://www.rcgroups.com/forums/showthread.php?t=2240626

If you buy a RedBrick without BEC (they are labelled as OPTO), you can safely remove the heatsink on the MCU side.
If you have the BEC, use a dremel to cut the corners near the + and - wires (battery side).
If you want something more reliable, and a little more expensive, the Plush series has received
good reviews...
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Last edited by ululi1970; Oct 14, 2014 at 02:53 PM. Reason: added link
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Old Oct 15, 2014, 06:49 PM
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Thanks for the help ululi70. That gave me some insight.

Anyone have ideas on this motor below? Running it on the ecalc, it looks like this would work alright for my plane with a flight weight of 5 lbs, and using a 12x6 prop, and using my 3s 2200mah batteries. I know flight times would be limited, but I could always double up batteries in parallel, to mimic a 4400mah battery. I would also use a 65-70 amp sbec esc, and it appears this may be a cheap way to explore electirc power for this old telemaster........

Would this motor work? http://www.hobbyking.com/hobbyking/s...trSearch=d3548
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Old Oct 15, 2014, 09:38 PM
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Canada, ON, Owen Sound
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IMO nothing wrong with the motor selection, but I'd use a 60A turnigy Plush and 2/2200/3s/25c batteries. ith the 12/6 prop. Should be plenty for the Telemaster, and provide adequate flight times. The 60 Plush has its own bec, a switching 3a type that more than enough for 4 servos.
You could use standoffs to mount the motor made from wooden dowels, or plastic spacers from Home Depot, or glue in a new firewall and bolt the motor directly to it. fwiw Doug B
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Old Oct 15, 2014, 09:41 PM
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United States, CA, Rosemead
Joined Jan 2012
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you need 70-90 watts/lb. @ 5 lbs auw, that means a 450 W motor (90 watts/lb x 5lb). the one you linked is 910W - bit of overkill. but it will do the job. look for 350-450W motors and those should be all you need.
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Old Oct 16, 2014, 12:43 AM
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manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
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You can use this guide. Use google translate incuided.


Converting a training model to Electric 40-46.

This model is very popular among people who are in the first and second stage of their learning, 55-60 inches of wing, 2.4 to 3 kilos in weight, 630-700 square inches, 92 to 100 oz. weight and with a wing loading of about 22oz.
His speed loss will be around 18-19 MPH.
They are called: trainer 40, Spot 46, CALMATO so.

When you are installing a .46 this takes a shovel for a 11x6 11.600 to 12.000 RPM.
And this gives us about 2.9 Kilos of thrust, 87 KPH, and 635 watts of output.
In an electric model the performance of this model is represented as 3 times the stall speed, 100% thrust and 141 watts per pound.

Or one 10x7. For a 12.600 to 13.000 rpm.
And this gives us around 2.4 kilos of thrust, 110 KPH and 685 watts of output.
In an electric model the performance of this model is represented as 3.79 times the stall speed, thrust 82.7% and 152 watts per pound.

More.....
http://aeromodelismoelectrico.blogsp...enamiento.html
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Old Oct 16, 2014, 01:34 AM
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Quote:
Originally Posted by Doug Bartley View Post
IMO nothing wrong with the motor selection, but I'd use a 60A turnigy Plush and 2/2200/3s/25c batteries. ith the 12/6 prop. Should be plenty for the Telemaster, and provide adequate flight times. The 60 Plush has its own bec, a switching 3a type that more than enough for 4 servos.
You could use standoffs to mount the motor made from wooden dowels, or plastic spacers from Home Depot, or glue in a new firewall and bolt the motor directly to it. fwiw Doug B
Thanks! I will look at the plush esc's. I assumed 65-75 A esc, because that is what the calculator recommended. Yes, I was weighing my options on the mounting, and since I will probably need some weight up front, I think I will just make a second firewall in front of the original, and mount the motor to it. I just need to research the angle I need to install the firewall at, to make the thrust angle correct.
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Old Oct 16, 2014, 01:37 AM
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Quote:
Originally Posted by cmdl View Post
you need 70-90 watts/lb. @ 5 lbs auw, that means a 450 W motor (90 watts/lb x 5lb). the one you linked is 910W - bit of overkill. but it will do the job. look for 350-450W motors and those should be all you need.
The motor is 910 watts with a 5s battery, as far as I know. The caculator, shows that when used with a 3s battery, that motor is at 432 watts, which should be about perfect for a trainer, and let it just about hover.
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Old Oct 16, 2014, 01:48 AM
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manuel v's Avatar
Mexico, BC, Mexicali
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Quote:
Originally Posted by Jimbo45 View Post
The motor is 910 watts with a 5s battery, as far as I know. The caculator, shows that when used with a 3s battery, that motor is at 432 watts, which should be about perfect for a trainer, and let it just about hover.
You thought about the balance, the engine is very light weight.
best looking one equivalent of 200-300 grams.
Better balance, more efficiency, less heat and longer life.

Manuel V.
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Old Oct 16, 2014, 10:51 AM
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United States, CA, Rosemead
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Quote:
Originally Posted by Jimbo45 View Post
I just need to research the angle I need to install the firewall at, to make the thrust angle correct.
5 degrees down and right (at least 3 degrees) should be sufficient thrust angle.
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Old Oct 21, 2014, 03:45 PM
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Thanks for all the help guys. I ended up with this motor

http://www.hobbyking.com/hobbyking/s...00KV_815W.html

and a Turnigy AE-65A brushless ESC, http://www.hobbyking.com/hobbyking/s...dProduct=35675 and a dozen 12x6E props. According to the calculator, that should be a good match, with plenty of power at 475 watts and 75oz thrust. I will double up 3s 2200 batts, and have a pretty decent flight time. Can't wait to get this stuff and figure out how to mount the motor!

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Old Oct 22, 2014, 08:39 AM
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United States, NC, Chapel Hill
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For the motor mount, there are a couple of options:
1) you can fabricate a mounting plate with plywood, and use threaded rod
with nylon spacers (or use aluminum tubes), to position the plate at whatever distance from the firewall it takes to have the prop at the right position
or
2) if you still have the original engine mount, you can use little L brackets
(I get them at the hardware store, Stanley brand, under cabinet hardware)
to attach the firewall to the old engine mount.
or
3) If you trust the strength of the cheeks, you can attach the new firewall
to the cheeks and mount the motor to the firewall.
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Old Nov 04, 2014, 12:32 PM
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I remorked the old nitro engine area....removed the bottom portion and rails, and recovered the front. Motor spacing and mounting came out pretty well! Got the motor and esc and receiver mounted! I also modded the hatch behind the firewall, with magnets, for a battery hatch. Stuck the batteries in, where they will sit, and checked CG, and it was almost perfect! Now, I just need to craft a battery cove from foam, and fine tune the balance, and trim it out, and she will be ready!



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Old Nov 04, 2014, 04:31 PM
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Battery cove complete. Made it out of foam I glued in, and they fit snug and should be protected in a crash. Its almost like this plane was meant for batteries!!!!!!!!! Now I just need to hook up the servos and program the ESC, and trim it out, and check balance and CG! Woo Hoo! Thanks for help guys!



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