View Full Version : Easy Sport conversion

06-08-2006, 09:38 AM
This is my first attempt at a E-conversion, and I'd be interested if anyone has any suggestions/advice. I'm a bit concerned about any issues I may have with prop clearance on the model being a tri-gear, I'm not sure if I'll need to modify the landing gear at all. I assume the battery will need to go where the fuel tank would be for correct CG, although at this point I'm only guessing:confused:

Motor: E-Flight 46
Battery: Kakam LiPo 4800mAh 4S 14.8 volts
Esc: Jeti Master 70-O-Flight



Matt Kirsch
06-08-2006, 03:04 PM
Hey MrFoo, welcome to the world of big electrics!

That's a good combination for that plane. The battery doesn't look like any Kokam I've ever seen, though. Where'd you get it?

I ask because there are some unscrupulous types on Ebay that sell FAKE Kokam packs. :(

06-08-2006, 03:54 PM
The kokam, I believe its from Malaysia. I've used smaller packs from the same dealer, with no problems. But you can't be too careful with lipos of course!

Do you think I'll need to make any openings to cool the ESC? I've seen this done on a few E-conversions.

Matt Kirsch
06-08-2006, 08:56 PM
Cooling is definitely desirable. Either opening up the firewall, or adding a chin scoop just behind the firewall for an intake, and opening up a generous area on the belly behind the wing for an exit...

06-09-2006, 02:02 AM
Should make a nice conversion. I just mounted a power 60 in a Hangar 9 Twist. I used the backplate mount that came with the motor and some nylon standoffs that can be found in the nut and bolt section of Home depot.

As for balance, build the plane. (glue the tail on, mount the wing, etc)
Now mount the motor. Now you can move the radio gear and the battery around to get the balance close. I try to leave a little room to move the battery around. This way, I can fine tune the balance.

Hope this helps and be sure to let others now how it turns out.


06-09-2006, 08:46 AM
Good suggestion, thanks. Hopefully the sliding motor mount I have will do the job. The prop is a 13X8, so it will be interesting to see how much clearance I have. I hate to have to modify the landing gear or anything, I'll soon see.

06-24-2006, 03:18 AM
I am presently in the final stages of an Easy Sport e-conversion. I chose the taildragger version and the same motor/mount/prop as you. My battery pack is a Tanic 4s 3650mah. I incorporated a long battery tray because of uncertainty of where the battery would go. It turns out to be quite far forward (front is about 1 1/2 inches behind the firewall. Did the weigh-in this AM. Looks like 20 oz/sq ft with a rx/servo pack (I may go to a ubec at some point.

Can hardly wait to try it!


PS I did qite a bit of balsa removal from the fuselage and wing for weight saving. The kit ssemed to be quite rugged to handle a glow engine. Hope it will still handle aerobatic flight loads!

06-24-2006, 01:32 PM
Thanks Navkan, hope it goes well for you. I maidened today and the easysport couldn't be any easier to fly. I'm very happy with it.
I had to move the batteries as far back as possible to get the cg correct, and I ended up placing the receiver in front of the rear ventilation opening. It actually worked out pretty well, I'm not sure where I would have put the receiver if I hadn't cut those openings! Still, I may be a bit tail heavy with the battery in the current position so I may move it forward

The only problem I had was the flying time which was only 3-4 minutes, and I expected maybe 10-13 minutes on half throttle. This meant I had two deadstick landings (thankfully the instructor was excellent) but even then the Easysport handled nicely and we got it down safely.

Can anyone suggest what would be draining the battery like this? The dealer I bought it from checked the settings on the ESC so I assume that it's set up correctly for this motor and battery. I do have a few long leads such as the throttle lead running along the fuselage, not sure if that causes any issues. Would using too many extention leads have an effect?


06-25-2006, 03:20 AM
Hi MrFoo
Nicely done conversion. CG positioning on "electrocution" can drive you crazy at times - sometimes, these ready mades aren't all that precise on structure vice balance issues and can be really way out at times. Add a conversion to electric power and who knows where you can end up with the CG.

Your battery - hate to sound depressing, but is that a Kokam as supplied by FMA Direct, or someplace else using the name? That sort of thing goes on too much nowadays. It is possible that your particular pack just doesn't like what you are demanding of it. Pull full power and the battery voltage drops sharply, the ESC sees what's its been set as a low voltage and does what it was designed to do.

There's a lot of LiPo batteries around whose advertisements are far more optimistic than their actual capabilities...

BTW - if you start to chew up prop tips with that trike gear, toss it out, fit a ply - birch ply, not Liteply, plate in the fus bottom and fit a taildragger with longer legs for more clearance with the fuselage level. That set-up beats trike gear any day for grassfield ops.



06-25-2006, 03:48 PM
I'll check with the dealer later this week to see what the problem is. I did a test with an amp meter, I was getting 27 amps on half throttle, and 48 on full. I have noticed that the recharge times are short for a battery this size. I doubt the battery quality is a factor because the dealer is a reputable one, I don't think they would shift substandard lipo's. I'll double check on the manufacturer anyway.

06-25-2006, 06:25 PM
This next is staggeringly boring and doesn't involve the purchase of things "NEW! and "EXCITING!", but it might help you out as a newcomer to this electric stuff.

Can you fit a set of NiMh batteries in your model? 4S is probably replaceable by 14 x 3300 sub C sized NiMh in power - okay, your model weight will rise and I was going to say that your flight duration may drop, but right now you don't really have any duration.

NiMh are well proven, you can charge them pretty brutally and they don't mess you around, catch fire, burn down your house/truck/model flying site and other little foibles of LiPos. Chargers are relatively simple - I use a couple I've had for many years and they do just fine - and my only other support gear is a cooler tube. A cardboard mailer tube and some kind of computer blower fan will do fine for that.

Don't say they can't perform. I have a 14 cell aerobatic model, weighs 5.25lb RTF, that would gets seriously upset over that, and quite a few have said that she can kick some serious aerobatic backside.

State of the art in NiMh is a colossal 4300mA from GP. Last I bought any NiMh cells, Robot Power Solutions were as good as they come for price and service:-


You'd probably have to re-arrange the inside of your model to fit a set, but you sound capable of that. It would let you get on with getting the feel of electric powered RC, do some flying and not have to worry about Lipos - which, and I realise this is somewhat against marketting and advertising, are not quite all we're told they are.

If you understand the best end of a soldering iron to hold, making up a battery pack is not magical by any stretch.

Your amps figures - flat out is the killer. Half throttle won't tell you all that much. If your pack has any problems, it could experience a volts drop enough to cause the ESC to shut you down almost on take off. Problems could be a defective cell, a pack that's just not up to spec or inferior cells - if you get a flame out on take off, it won't really matter to you which it is, the result will be the same.

Your short recharge times for your LiPo suggests that you're not taking much out of it - the short flight times are another hint. That leave the above to be looked at.

WIthout any faults being present, I'd be inclined to trust Kokam if they came through FMA Direct. FMA Honcho Fred Marks was possibly one of the first US e-fliers to fly with lipos - he's in my club, caught him doing it years ago - and he's real good guy.

OTOH, these batteries do come from a part of the world that can't spell 'business ethics' ...

Keep plugging away!