HI, I'm building a European trainer kit called a Parat for my kids. Because I hate emergency room visits I decided to build this as my first electric ( yeah I got a few stitches when I was 12). The old kit came with a gigantic can style motor which everone said to put in a truck or the garbage. I don't want to sound like a moron but I'm confused as to what to buy for power and control ( it's already a difficult build due to metric/sae conversions and German to English translations). Anyhow this plane has a 48 inch wingspan give or take a millimeter or 2 and a 36 inch fuse. I'm building it with strip ailerons and no dihedral. It looks alot like a Sig Kadet but smaller, The wing is almost identical but scaled down. The plans state the weight of the electric version @ 1320 grams and the nitro version @1060 grams . The nitro version of this plane calls for a .09-.15 Cu. In. engine (if I did my coversions right). I thought given the extra weight incurred by batteries that a .20 cu. in. nitro would be just right so I went to the hobby shop and said give me a brushless motor that will preform like a 20 size nitro. I thought it would be simple but I left confused and without a motor or speed control. Don'tget me wrong the hobby shop owner was cool and advised me to build the plane and bring it in then we could find the best power alterantive but it bugs me when I can't understand something that seems like it should be simple.
Is there some sort of simple converion table for nitro to electric?
Any suggestions as to how to power this plane would be appreciated !
What is the most bang for the buck in electric power?

The conversion tables from Nitro/gas to electric are not exactly precise. They are general ballpark conversions. It is easier to just get the weight of the plane and start from scratch.

Everything in terms of Electric Power is based on total watts and watts per pound of aircraft. Here are some general numbers to look at for Electric Power based on the desired performance of the aircraft - 80 watts per pound for a trainer - 120 watts per pound for aerobatic - 150+ for 3D and unlimited performance.

Say you have a 3lb. plane that is an aerobatic model. The first step is to figure out how many total watts of power you are going to need. So take the 3.0lbs and multiply by 120watts per pound for aerobatic = 360 total watts required. That is just step one, but it will help you pick a motor and battery combo. that can deliver the required power. One step at a time so it does not seem overwhelming

Is the 1320grams an all up flying weight with everything included for an electric version?

captken 59:

We all start somewhere in the learning process, its best to follow someone else who has allready paid for the mistakes and knowledge. Find a good HS/retailer known to know his stuff, and use him where possible. So far, when trying to match gear to airframe, I go to the sites that are smart enough to give motor thrust numbers. If you are building a 4 lb airframe, you will want at least a 4 pound thrust motor. A sport model will probably fly at 1/2 thrust/weight ratio, buy why push things. (3D 1-1/2 to 2 times weight) Now that you have the motor size needed, go to the motor needs to get your controller and battery. If you motor is designed to pull 25 amps, you want at least a 25 amp controller. A little fudge room is good, I would size to a 35. NOw its battery time. You want a good battery that will give you at least 10 minutes of flight time, usually a 3 cell pack. Weight is a limiting factor here. You will need at least two to enjoy flight time without waiting for one battery to charge. With motor, controller and battery, stay with the good stuff, Hacker, AXI, Phoenix and Thunder Power have proven to me to be good quality gear, Do not buy the weak motors that require a gear system to make enough power to fly, just a way to use cheap stuff rather than the higher end. No such thing is good and cheap. You will end up spending more in the long run to by the cheep stuff, cause they seldom work well, and only for a short time regardless. Li-po is the best way, overall to go. Go to the rcu electric site and learn how to estimate the size of battery needed. I generally rely on the recommended lipo battery size from the dealer, but you need to learn enough about electrics to make confirming decisions youself. Smarter dealers like Horizon, Hobby People, rcx planes.com, will give you good recommendations in general, based on actual in house use, and testing of the actual equipment. If they do not, do not buy from them. Most will offer a economy package and a recommended package. Spend the bucks now, not later after learning the geared motor and cheep battery system is not up to snuff, even though it works for a while. Motors ourchased 3 years ago are still running well in my stuff. They die from crashes and pilot dumb thumb, not wearing out. Nothing worse that to loose a great bird because the motor went up in smoke, or the ESC pooped out. Just dose not happen with the good stuff. Bottom line, learn, learn, learn from the RCU web site, its all there if you take the time to read. It will be much more fun to have a good idea of what you are doing, and how to. Find someone in the local club that runs electrics, and run stuff by him. Get a Watt meeter, so you will know what your system is doing. A good way to select props is based on actual draw to the motor. Will perform much better, and not overprop and damage your equipment. Amazing one size pitch or length will make. A good motor ECU and battery system will not ever become hot to the toutch when ballanced correctly as to size. If it gets hot, your doing something wrong. Hope this gets you into the right direction. ENJOY

I'll add one thing....

electric motors and props can do just as much bodily harm as glow...............

well, not really. With an electric you can instantly turn off the motor. With the glow engine, you would have to drop the RPM to idle and then kill the motor. Lot more complex than an electric. In that sense.

Actually, with a prop strike and glow engine, the engine typically quits. With an electric the blades just keep cutting until the battery runs out.

Thanks for the input. in response to Flipprob The 1320 gr. is "Fluggewicht mit RC-anlage" I Think that is an all up weight but the German thing is cofusing. Exeter , I understand there is still a danger factor with electric but at least the kids won't be messin with needle valves 1/2 inch from the prop or trying to finger start a glo engine ( yeah kids learn about chicken sticks the hard way). Still no one has been able to say what electric will preform like a .20 cu in glow engine

I think part of the answer depends on what kind of 20 you are looking at.

Using the 46 - 50 size range as an example of what I mean, there is a BIG difference between the power of and OS 46 LA and an OS 46 FX. Even more difference when you get into somthing like the Irvine 53, OS 50sx, and higher engines like the JETT engines.

For something like an OS 25 LA you may want to look at the Hangar 9 power 25 BL, it seems to similar.

Based on your original post, you may want to consider the power 15 also.

Or until one or more of the blades break off and the motor shakes itself out of the plane. Hell hath no fury like a 500 watt motor with major unbalance turning at 5K. In the milliseconds it take for you to hit the kill switch it is all over. Also no glo motor ever started by itself while you are fiddling with the plane trying to adjust something. [:'(]

So we are looking at 46.5 oz, or approx. 3lbs...........hey look at that.....those were the numbers I already ran Somewhere in the vicinity of 360-410 watts should do the trick.

Motor Options on a 3 cell 11.1 volt LiPo:
E-Flite Power 10, Himax 3516-1130 (on the low end of the watt range)

(you could go up to a 4cell 14.8 volt LiPo on these, but probably do not need to, benefit is more watts running less current=longer flight times, but you are forced to run a little smaller prop.)
Himax HC3522-0990 - 400-430watts
E-Flite Power 15 - 425watts
Axi 2820-12

As for a 0.20 electric conversion - it would be closer to the E-Flite Power 10 or HImax HC3516-1130 class - 350-375 watt motors