Electric Conversion - RC Groups
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Dec 29, 2017, 03:53 PM
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Electric Conversion


So I am really new to building my first RC plane. I have done a lot of research and am sticking with the Sig clipped wing 1/6 model. The model calls for a gas power system. My question is what prevents me from just building it as an electric system?
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Dec 29, 2017, 04:10 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by fsk714
So I am really new to building my first RC plane. I have done a lot of research and am sticking with the Sig clipped wing 1/6 model. The model calls for a gas power system. My question is what prevents me from just building it as an electric system?
There is an RC Groups forum for IC to electric conversions :

https://www.rcgroups.com/glow-to-ele...nversions-247/

If you are in the USA , the quick and easy way is to call Heads Up RC and ask him for an electric motor equivalent to the IC engine your plane calls for .
http://www.headsuphobby.com




Will you be using this plane for first time RC flying ? If so , will you have the assistance of an experienced RC flyer ?
Dec 29, 2017, 05:14 PM
Here to just enjoy the hobby
Rhea's Avatar
I did a similar conversion with The World Models 1/6 Paulistinha P-56.

I used a Power 46 size motor with a 4 cell Lipo. You will have to get everything as far forward as possible. I had to put a Harry Higley's Heavy Hub hidden under the spinner to get it balanced.

Good luck. You will enjoy the build and the flying is great fun too.
Latest blog entry: All things that fly.
Dec 29, 2017, 07:59 PM
Registered User
Thanks, I guess my concern is what if anything prevents me from making it an electric motor? Assuming I get an electric equivalent to the gas size?
Dec 29, 2017, 08:36 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by fsk714
Thanks, I guess my concern is what if anything prevents me from making it an electric motor? Assuming I get an electric equivalent to the gas size?
Nothing I can think of . You'll probably have to figure out a way to mount the electric motor in the place designed for an IC engine , but I don't think that will be difficult .

Again ( this question is important ..... unless you want a lifetime supply of toothpicks ) : will you be using this plane for first time RC flying ? If so , will you have the assistance of an experienced RC flyer ?



Let us know how it turns out , with video if possible .
Dec 29, 2017, 09:11 PM
Here to just enjoy the hobby
Rhea's Avatar
Quote:
Originally Posted by fsk714
Thanks, I guess my concern is what if anything prevents me from making it an electric motor? Assuming I get an electric equivalent to the gas size?
Nothing will prevent you but as noted you need to get the balance (weight) forward to match the weight of the IC engine.
Latest blog entry: All things that fly.
Dec 29, 2017, 09:57 PM
If it flies, I can crash it.
rocketsled666's Avatar
If you need to modify the model for the electric conversion (say, for instance, to add a battery hatch) and this is the first model you've ever built, unless you're a mechanical engineer and you know what you're doing, you might want to choose a model that was designed for either electric or gas instead.

Also, generally speaking, electrics can be built lighter than gas. So if you convert a gasser that wasn't designed to be converted, you'll end up with something heavier than it needs to be. Extra weight equals lower performance, and this can be particularly important for an Electric.

That being said, a google search for "sig 1/6 clipped wing cub electric conversion" delivers a number of hits, some on RCGROUPS and some on other forums. So you're not inventing the wheel here. Should be fairly easy to do since others have already done it...
Dec 29, 2017, 11:09 PM
Here to just enjoy the hobby
Rhea's Avatar
Take a look at this thread to see how others have done it.
Latest blog entry: All things that fly.
Dec 30, 2017, 01:22 PM
B for Bruce
BMatthews's Avatar
Looking at the web page for this model I didn't see any weight given. So I looked up the link for the CONSTRUCTION MANUAL to see what it looks like.

This is one gas model that is built more like a lightweight electric than it is a gas model. Looking at the construction for the wings and the "stick built" fuselage I can't imagine a lighter way of constructing a model of this sort. It really is built up much like a giant stick and tissue rubber model or an old time free flight gas model in very many ways.

As a result I suspect that it will not be at all hard to build this model such that it comes out at around 2.5lbs. And at MOST it should be 3lbs. And do yourself a favor and don't add weight with things like the cowl reinforcing. Just keep the motor and battery pack close to the front. In fact as part of the modification you may want to split the cowl such that the lower part comes off and cut a hole through the firewall and arrange a battery mounting board so you load the battery packs through that lower cowl access. You will need to make up a motor mount that extends forward anyway so it would not be too hard to include a couple of upper cowl half shell mounting points.

For holding the lower cowl in place you can either use super magnets or jacket snap buttons. Or some other option.

Of course all this depends on where the battery pack needs to go to achieve your balance.

Now what motor to use? I assume that since you are building the more aerobatic clipped wing version that you want to have some lively performance. That suggests something around 100 watts per lb. So you might be looking at a motor that will handle a maximum of 300 to 350 watts. This means if you follow the 100 watts per lb idea that you would run the motors with a roughly 50 watt safety margin to aid with keeping them nicely cool in operation.

You could go more but do you really want an unlimited vertical climb? At 100 w/lb you will have an nearly vertical climb already when using a larger diameter and lower pitch sort of prop.

The crazy thing is that the manual link above lists the power as 75hp for the full size. Having seen such Cubs fly with that much power to duplicate that in the model you would run at more like 45 to 50 watts/lb. And perhaps even more like 40 to 45. At 100 w/lb you are up to a climb rate and angle of a lightly loaded down WW2 fighter plane when at full power. And as you go up over 100 you step into modern jet fighter power to weight ratios.

A final if rather long worded hint since you say this is your first build. The fit of the longerons and uprights needs to be pretty critical. Altering the fit of the uprights for angle and length by the thickness of a sheet of printer paper is the difference between good and poor. Start with the long ones and if you overshoot and make it too loose use that piece for the next shorter upright. It is also best to use aliphatic wood glue for these joints instead of the rather brittle CA glue. And when you put the glue onto the ends put a small drop on, rub it in with your finger to aid in filling the end grain then apply a little more and place the sticks. And "wipe" first one end then the other to transfer some of the glue to the longeron before you push the stick into position.

The fit you're looking for is a very light finger push or a no pressure finger push with no play or just the barest visible play. Any gaps should be small enough that you really need to squint to see them. This will produce good strong yet surprisingly flexible joints that last through all but the worst accidents.

To get the initial cutting lines I offer up the sticks to the position they will go and then use a knife to mark lines which you feel are at or slightly outside of the final size. I then cut a little outside that line and start sanding to fit using the scribe line to guide me for the angle of the sanding.

The first couple of dozen sticks will seem like you will never get it right. But stick with it and rapidly you'll get fewer and fewer "short pieces to use in the tail" and it'll go well.

A couple of accessories for cutting and sanding the uprights to size are benchooks that I made for use with the razor saw and a sanding block for trimming the ends. I've been meaning to post a thread about them so now is the time. I'll post a link back to an edit to this reply in a little while. These two things really do make fitting the uprights a lot easier.

A rather long reply? Yeah, I know. But while it'll be rewarding to build it's not the easiest choice for someone new to building models in this manner. So if my tricks above aids you at all then it was worth it.

Welcome to what I consider the side of the hobby which is every bit as much fun as the flying.

EDIT- Here is a link to the BENCH HOOK thread I promised.
Last edited by BMatthews; Dec 30, 2017 at 01:58 PM.


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