Which motor?
 

Hi, I'm just getting into electric RC so I know nothing.

I'm curious what electric motor would be good for a custom built airplane that would be about 3 ft wingspan, lightweight, medium-fast speed, etc. I assume that Lithium-Ion or Lithium polymer batteries would be a good choice, but I really have no idea what manufacturer, model, voltate, size, amp draw, etc specifications I would need for a plane like this.

Thanks for any help!

RE: Which motor?
 

There are alot more factors to consider than weight and wingspan. The type of airfoil, application (ie. trainer aerobatic ect), gearbox/propsize ect.. Since the plane is being custom built maybe you can go the other way around and choose a motor/prop and build the plane to suit it. Using other planes that have proven succesful and are in your size range is a good way to start and then model your plane the way you want around those parameters. Learn the general rules of watts/lb for your application so you don't end up with a dog or something that shreds your firewall when you max out the power.

RE: Which motor?
 

Three letters for slowflying:
IPS
GWS's IPS line puts out enough power for a 36" plane, and with some E-tec or kokams (1200 is reccomended-but be prepared for LOOOOONG flights) you can keep the weight to a very reasonable 7 ozs.. The EPS100 is good for a bit more oomph-and you can get parts for both EVERYWHERE.
Me, I like FoamFly.com-it's a ma&pa sort of place, but it's full of free plans and useful oddiments. Parkflyermotors.com is also good, but you can get these things ANYWHERE. Plus, you can just get a Pico Cub-stick, which uses the IPS and comes with pushrods and a propeller, for 10$ more-and use the wing on something else.
Then again, if this is a fast model, you want LOTS of torque without a gearbox, or simply like brushless, go with a CD-ROM drive motor. I see CD drives at OfficeDespot all the time for 5.00, and with a bit of coil-rewiring (I heard a delta-style pattern works best) and a few extra neodyium magnets, you have a motor equivalent to a Nippy Brushless 280 for a lot less-and you can replace parts far more easily, too.
Just my 2 cents,
-The Mac Conversado