how to convert 400 series P-51 or P-40 to R/C electric?

[shawn32671]

I'm seeking help and advice for converting a 400 series Mustang or P-40 to electric R/C, I have both kits new in box and would like help with either one on this conversion idea. Any help or suggestions such as optional ways to build the kit that would be better suited for the conversion and what electrics to use. I have a radio control set sitting in a box already but has standard servos and standard receiver. I assume I'd need at least micro of both or just micro servos and remove the receiver from its outer plastic case for weight and size savings? What motor and speed control would be best?...I'm doing this on a half a$$ed budget too so that has to be taken into account...any help/suggestions appreciated...thanks in advance.
Shawn

[Mitch]

Hi Shawn... I do not know too much on electronics, but I will give you some advice...

First a question: Have you built one of these kits before?
If the answer is NO. Then I would say build the P-40 as a rubber powered model. I built one, it flies. People say it is the best of the 400 for flying. I do not know for sure.
After you do that... or if the answer was YES then build the P-51 for R/C. My reason is the Wing is the easiest to make "PLUG IN" You will want the wing to be removable.
There may be other build threads on these conversions. You can look for those.
The completed model as per instructions in kit will weigh about 100 grams, that's less than 3.5 oz. Talk to the guys at a hobby shop (You don't have to buy) ask them what size motor.
You will want micro servos, and electric motor with a throttle control. So that's 3 channels. You will put 2 servos behind the pilot for rudder and elevator. You do not need NOR DO YOU HAVE THE ROOM for more stuff... These are SMALL models for R/C...

So my advice is build the p-40 for rubber... and we'll talk more after that... Mitch

[shawn32671]

I've built both the P-51 and P-40 as balsa rubber fliers in the past and both faired well. I really like the looks of the P-40 so that's why I'm hoping for an R/C conversion of that. I have found a little info so far as to what R/C system to use and possible motor speed control combos too but not enough.

[Bill Gaylord]

The P51 is the best of the series for ease of conversion, as it has no issues with balancing, given the long nose. Planes like the 190 and Zero require the tail servos and battery to basically be up against the firewall unless the tail is built light with no fuse sheeting, to avoid using ballast. I've converted the P51, 190, and Zero and they are all decent flyers, all a bit different. I don't see much use for a functional rudder, but I've added it on some just for scale detail. The Zero probably should be the best of the bunch, but I have a slight hysteresis issue with the single servo cable setup that could be corrected with a slight adjustment in the cable geometry at the servo, that I just haven't gotten around to. Individual aileron servos are much simpler, and I only use cables to shave every bit of weight possible, since I sheet the fuses/and/or/wings on these planes with 1/32" balsa. The P51 is the best flyer I have, and actually an excellent flyer in general. I think much of it is due to a slightly modified airfoil with Phillips entry, and slightly reduced incidence. The first inch of the bottom airfoils are tapered upward, and the wing panels are perfectly symmetrical with a gradual washout of around 1 degree. The effort put into having no warps and perfect symmetry is worth it. These flat bottom airfoil planes are known to be speed-trim related climbers, and the P51 is the only one I have that trims perfectly without any of that, while also not needing downthrust to accomplish it. All said, the P51 is a much better rc flyer than I ever would have expected it to be.

Power wise, there's no issue with overpowering these planes a bit, as the shorter nosed warbirds like the 190 and Zero essentially need the weight of a 370 series motor, and modern lipos at small sizes of around that of a TP 900mAh have provided plenty of power and ample flight times. My P51 has a geared bl 370 and really doesn't need all the power, but it's fun to have, flies fine at it's weight, and wouldn't lighten up all that much with a slightly smaller motor. Depending on how the plane is built, a 200-300 series motor can be ample, but there's not much purpose to using a smaller motor with lead ballast also, versus a slightly larger motor. People seem to like to over-servo also. I haven't had a failure using servos as small as 3.5gm for these planes. The 5gm range has proven plenty ample, and I try to avoid using servos in the 9gm range of the HS55 as it's not necessary. The weight does add up.

Mitch has a good comment about the P51 plug-in wing. I did one plug-in, and it works really well and is really strong. It has blocks on the top of the rear wing that slide snug inside the wing saddle formers, and a spring latch at the leading edge of the wing. The lower cooler of the P51fuse positively holds the rear wing in place, to keep it from dropping.

Another thing I think Mitch was getting at that is very true, is that getting the planes to fly well is the biggest hurdle. I jumped right into electric conversions with Guillows planes, and should have spent time learning the importance of perfectly straight building, CG setting, and many other things. I would have been better off starting out in ff, rather than rc. The specific rc gear has a good bit of flexibility, as long as it's reasonably well matched to the app, where the airframe is much less forgiving. While all learning experiences are good, I learned much more the hard way than necessary.