Starting a great planes pt-40 build - RC Groups
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Nov 13, 2012, 05:24 PM
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Starting a great planes pt-40 build

I want to go electric and believe the propeller will be a 10x5 as I understand. looking for a turnigy motor - something I can easily afford to blow up as my first motor in the plane. if all goes well will build bigger with better stuff. So can someone recommend the motor I need to pull this near 6 pound plane through the air wit the B wing, the aileron version...looking for the motor, the esc and a battery rec. thanks so much guys. This is so difficult as there is no standardization between manufacturers to compare motor to motor. Not simple stuff for sure.
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Nov 14, 2012, 12:15 PM
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A place ot start, maybe?

And, of course, here:
Nov 14, 2012, 12:21 PM
Just a word of advice if you are building a balsa kit. I built a pt60 and it came out very tail heavy. I ended up putting a quarter pound of lead in the nosse along with the plain bearing .60 .
Nov 14, 2012, 01:49 PM
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dedStik's Avatar
I did a PT .40 conversion.

There is also a fellow here on RCG tenspeed I believe is the name that has a PT .40 converted to electric.

Mine still has yet to be put in the air, but I'm confident the power system I've got will more than handle the 6 lbs of weight.
Nov 16, 2012, 01:13 PM
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dedStik's Avatar
Any updates to this project?
Nov 19, 2012, 09:24 AM
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She's happening. I am modifying the fuel tank baya nd sitting with paper and pencil to get the desing I want. I moved the forward firewall forward to a distance that would allow the prop to be in the right place with the outrunner behind it. This elongated my "fuel" tank area and so I am making a light plywood tray to allow for aft battery movement. Additionally I have converted her to a tail dragger. Reinforcing floor with layers of 1/4 incha dn 3/32 ply and tying into the bracing with 3/8 bass wood stringers. Am Seriously consider putting a cold air scoop ont he bottom of the now batery compartment, lightening holes in battery tray and an exhaust scoop in the battery compartment lid. This would allow cold air in, warm air out and give me a handle for the compartment lid...which is held down with magnets as I have a ton of rare earth mags in micro sized. So that is where I am, trying to design changes and build them in order to get them all in to fit well. Also going to two wing servos and a rear skid instead of wheel. Talk to you all soon, will try to get some photo's but I am a lousy builder. Scott
Nov 19, 2012, 09:46 AM
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Ded I have read that thread over and over and love the color scheme, can you share how you did it? I am hoping to go with translucent wing panels and then add a dark boarder...maybe a light yellow translucent over the ribs then trim in black...your blue is my black and your white on wings is translucent yellow. I also went with double ailerons...did you do that as well? Hoping my motor decisions and batteries and esc's all play nicely together. It is by far the most confusing issues associated with the build. I think the out runner physically is a bit small, a 32/35 770 kv....not sure what that is going to mean in the end. May end up increasing engine size but this build is a bit on a budget. Scott
Nov 20, 2012, 10:11 AM
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Well I spent two hours working on her last night and confidently say I epoxied two formers together and that was it....lots of design thoughts and mock up looking at what I am doing and what order they need to be done in and when to do them. So with plan in hand I am going to get some real work done this weekend after TG. Hope to get a photo or two up soon. Scott
Nov 20, 2012, 12:59 PM
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dedStik's Avatar
I used the single servo setup with full length ailerons (the way it was originally built), I did replace all servos in the plane.

I chose to go with the Turnigy .46 for a powerplant. The plane originally had an OS Max .40 sized motor so the .46 should give me more than enough power. I did have to extend the legs on it a few inches to accommodate the larger prop, I think I have a 12 inch on it now.

As for the color scheme, I mocked up an outline of the wings in photoshop and drew out a few designs. This allowed me to print the designs to paper and then place them on the plane to get an idea of how it would actually look. Once satisfied with the design I printed it out, then glued it onto cardboard so I could use that as a template to cut my monokote. For the fuse I pretty much already had an idea of what I wanted to do with it.

On mine I kept the firewall intact (pretty much) I did punch a hole through it to run my motor wires and to allow for some air to enter into the battery/esc compartment (the old fuel compartment). I did punch a hole in the first bulkhead to allow the backside of the battery to slide in so I could balance it without adding dead weight. I also took some lite ply and made a battery cradle under the l.e. of the wing where the battery pokes through that bulkhead, this also keeps the pack from sliding back during climb. The top of this lite ply cradle makes a nice home for my RX. I tried my best to add as little dead weight as possible in the conversion. I got really lucky that the plane never really flew much past engine break in. There was zero fuel damage to the wood.

I also used aluminum tubing cut down to make my own motor stand offs to allow for the proper clearance for the prop and spinner, as well as clearance for the front gear mounts. I used a few washers to give me my down and right for thrust offset.

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