How about some feed back fellas!

I have been poking around on the HobbyKing site, just to brush up on the items discussed here - my initial reaction is that a 54-60 oz model should be fine on a 4 cell setup.  One combination that we have flying here is the Turnigy SK3548-900 on 4 cells.  Plenty of power with a 12-6 for a model of that size, with adequate headroom for a governor mode ESC to do its thing.  It will also handle a 13" prop and the extra current that it requires.  I have also been using my Twister as a 4 cell testbed with a 900 Kv motor and a Phoenix 45.  Weight is probably right around 51 oz, like it was with a 3 cell setup, and the power is way more than needed.  The 3 cell/1100 Kv setup drew an average of 3000 mah for a 'full-pattern' 5:30 flight.  It appears that the 4 cell/900 Kv setup will be under 2500 mah (maybe even less) for the same flight (both using a 12-6 prop).

If you really want to do a 5 cell, I would opt for a motor with a lower Kv -- in fact, I think even with four cells and a governor mode ESC, you could get by with a Kv of 750 - 850.  You could choose a C4250-700 or even an SK4240-750.  There is also one of the 'red & blue' motors - a 3548-850 that I've been thinking about giving a shot.

I would also like to point out that the SK line is a step up in quality over the "C" line motors - they have better magnets, better bearings and (in the 35xx size, at least) larger shafts.  That said, I have flown the Twister with both an SK3548-1100 and a C3548-1100 and there is no discernable difference in the way they fly on the Twister.  The main considerations there would be if mounting it in a full-fuse, that you get some cooling over the motor and battery, whichever model you choose - I can tell you that it is possible to cook a motor if there is no cooling and as soon as I get it re-wound, I can tell you if the Kv was a little too high or not.

My Panther has been flying with the Tgy 3548-800 very well. Spins a 12-6 APC with no problems and will go a lot faster than needed. The plane is 47 ounces, so lighter than you're are talking about, but my guess is that it will work fine.  The 3D RC guys work these motors a lot harder than we do. I'm only using about 2100 mAh (Zippy 4S pack) for the full pattern, plus 2-3 extra clovers at the end, 340 second runs, and the motor is barely warm with 60 deg ambient temps.

Hope to get some data this weekend with the Vector on the same power train, but with the ICE 50 ESC, so can tell more then.

We're having fun now!

John

The Turnigy Aerodrive SK 4250 is a 650kv motor, which I have paired with the TGY 3300 5S battery. Not in the air yet so can't report on results, but the Adamisins are using this TGY motor in a Strega with good performance. This motor gets high marks from RC 3D users, too. Check out the thread on "motor choice for larger models" a month or so back. Your 630" model probably does not need or want a motor this large, based on what I have learned here. The AXi 2826 series would be plenty, and the equivalent Scorpion is about $30 less. Both are available in kv ratings to use either 4S or 5S batteries to get into the right rev range. The smaller TGY Aerodrive SK 35-48 series should be fine, but again I have no personal experience with it. It has a 5mm shaft as do the 42 series (and the AXi and Scorpions). The 4250 is 9.1oz while the AXi is 7.1, an important difference that far forward. The SK 35-48 is 6.9oz.

Steve,

You mean I won't be the only electric at the Dallas contests next year?


Robert Compton

John,

I have a 35-48-1100 SK that is an absolute stump puller.  For Stunt, I would recomend the SK 35-48-900Kv  as on 4S it would give plenty of RPM for say a 13 x 4.5P and a bit less current than the 1100 Kv.  Cut it down to suit, but it will turn the full 13" no problem.  I would also use 4S 3700's from Turnigy to save money if that is what you are looking to do.  You might find that as you optimize the system, you may be able to get down to 3300's.

Archie Adamisin
Muncie, Indiana

John: I just ordered a complete Turnigy setup to convert my Imitation to
e-power. Should be a piece of cake with the firewall front end. I'll let you
know what I think when I get it in the air.

Steve

Thanks Steve, much appreciated and I look forward to your findings and opinion.

John,

Let me know when you have an idea of final weight, desired lap time, and line length.  I would recomend the 13 x 4.5P prop.  You may decide to chop the diameter if you don't want to run all the diameter, but a 640 sq in bird should be able to handle it.

Whatever you decide, I can send you a program for your controller to upload and should get you within a few tenths of your desired flight speed.

Can't wait to hear how your ECL model goes.

Archie Adamisin
Muncie, Indiana   

Thanks again Archie, I cant wait either. I will stay in touch . Your time and help is greatly appreciated!