Optimizing the T52 for speed 400

(The ideas presented here are applicable to almost all our foamies, check the pictures out)

The T52 and 1/12 scale P51 are rather large planes for the lowly Speed 400 motor. However, they will fly very well with a few modifications. First, light radio gear is a must. We use FMA S 80, S90, or S100 servos because they are large enough to adequately handle the control surfaces yet small enough to help with the overall weight criteria. Most of the later model receivers are small enough not to be a problem. FMA makes the Tetra micro receiver which is a wonderful setup for this type of plane. Use one of the micro speed controllers to further help keep the weight down. The Aviox A20 is a great little controller. We have all of these products available including battery packs. Just use the links to check them out.

Note: We discontinued the Mini-Olympus because the gears are not straight, so we now carry a metal gearbox that seems to work very well. With a gear box, you can use the ideas below but I will revise the procedures for using the gear box ASAP. For now though, you are on your own. It is not difficult at all to use the gear box, reverse the wire to the motor and figure out a way to mount it in the nose. The gear box has nice mounting rails built in so it is very easy. We just put a little all metal gearbox in stock that has ball bearings and three gear ratios. It seems to work great so go to the Flying accessories page.

The next thing to consider is to build the plane light. Like I said it will fly well just assembling it as the instruction book says however a few ounces can be saved by following a few simple modifications. Speed 400 motors generally don't put the same amount of stress on the plane as say a Norvel gas engine might, so things can be built lighter but still strong enough to handle the power.

You can start by lightning the tail. For large holes I use a hole saw or sharpened 1" dia. tube to cut holes in the coroplast tail, then put packing tape over the surfaces. Use a 1/2" hole punch for small holes in elevator or rudder surfaces. That takes a considerable amount of weight out of the tail. When building the fuse, do Not use strapping tape. Just cover with packing tape. The fuse will not be quite as bend resistant but should retain most of it's durability. If you smack it, go ahead and add one strip down each side. Use one strip of strapping tape at the wing spar area. Lastly, do not make a plywood firewall. Leave the doublers open at the engine room area or fill the nose with styro foam scrap and sand to the shape of the doublers. Do not use a bunch of strapping tape on the nose, under the doublers, it's not necessary. Drill a hole for the speed 400 motor in the front and make a suitable motor mount or use wire ties to cinch around the motor by punching holes through the doublers. Or better yet, use our new motor mount made specifically for this application. Check out the pictures!

	First lighten the elevator and rudder (if you are using one) sections of the stabilizer using a 1/2", or so, punch. Notice that I left a space for the elevator control horn, that's very important!!
Next, I used hole saws of various sizes to drill BIG holes in the rest of the open area. That works pretty good but the holes are ragged and need trimming or sanding. If you can think of a better way, Let us know! Here's the better way! Robert Wacht, one of our customers had this suggestion -- he heated a piece of copper water pipe with a propane torch and simply melted holes through the tail pieces. The resulting holes came out clean and very smooth. If you try this, be sure to do it with plenty of fresh air and out side if possible as the fumes could be toxic. Great idea Robert and thanks! You could just use the little hole punch like the one above and fill it full of little holes. That might end up looking better.
	Here's the Swiss cheese-ed tail. The P51 and subsequent kits already have holes in the part of the vertical fin that buries in the fuselage. The T52 Trainer doesn't yet. You will now cover the surfaces with packing tape. No need to cover the part that is hidden by the fuselage though. After covering, the tape can be shrunk just like mono-kote with an iron or heat gun. Go easy with the heat gun though as it can warp the plastic rather grotesquely.
Take the fuse and either apply the doublers and leave the engine compartment open or fill with scrap foam as I did here. Then sand the nose to a nice shape that approximates the particular model you are building. In this case a P51. The Combat foamie instruction say to make a 1/4 inch firewall and tape the nose up with strapping tape but for E-planes it isn't needed. Just stick the doublers on with 77 spray. Remember too that you do not need to run strapping tape front to rear on E-plane fuselage either.
I had to make a little ply motor mount but check our new aluminum ones out. They work great - this one didn't! Anyway, notice how the nose is sanded to a more scale shape, complete with chin scoop. Electric motors are a lot neater installation than gas. I have already cut a pocket for the speed control, battery and radio. They are connected internally with passage ways drilled through the fuse. I used a 1-1/4" drill bit to make the hole for the motor. Our new motor mount has tabs that can be bent back around the motor, sandwiched and taped or glued between the foam and the doubler, then screwed from the outside with little sheet metal screws. Remember to cut some vent holes. Use strapping tape, top and bottom, to conform the coroplast to the shape of the sanded fuse.
	This is the new mount. Notice the cooling slots. Bend the tabs around the front of the plane and glue or tape.
Now lets do the wing. This is an interesting variation. We supply the hardware for hooking up control surfaces with horns and wire but I wanted a little cleaner look. So I bent torque rods from threaded pushrod wire (available at most hobby stores). Make them just long enough to reach inside the fuse and not hit each other. Make a right and left then drill a little hole for the lever to poke in and epoxy the wire into the slot made by the cut rib of the coroplast. I used these little plastic things with 2-56 nuts to lock them in place to actuate the rods. Makes a neat setup and is only a little more time consuming.
	Now attach the ailerons according to the instruction but because of the torque rods you will have to fold the aileron over the bottom of the wing instead of the top. Notice that the center if the wing is taped thoroughly as the regular instructions say to but you only need one strip of strapping tape on the spar.
This is where the air scoop on the P51 is cut to allow the wing to fit in. It is attached later.
	This is the completed aileron servo and torque rod installation. The fuse is hogged out to allow the control arms free movement. With this installation you don't have to make a hole in the fuse for the pushrod wires. It's quite a bit neater looking.

This is a good shot if the complete radio placement. The motor is in the front (of-course) then the controller, and the battery on the CG. The radio and rear servo is used to balance the craft. I hit the balance close but was a little tail heavy so I had to lengthen the battery slot to slide the battery about one cell length forward. I hogged out the rear of the battery slot inside the fuse so the plug and excess wire would have a place to fit easily. Well this is it! It's not hard to convert foamie to S400 and they fly outstanding! They end up about 24oz with all the radio gear and decoration and will fly nice and easy. You could lighten it even more by punching holes in the wing and fuse but I doubt it would be needed. It already floats like a feather.
	The finished plane all decorated and ready for action! You might want to check out how Randyl Britten set up his P51 with a brushless 020
T52 speed 280 Gearbox installation
NOTE: the foam on the nose will need to be trimmed off a bit to put the prop close to the front of the doublers. Trial fit before gluing the doublers on.	This is the T52 using the little plastic gearbox we have available now. This is a semi-fragile unit so I would not recommend it for beginners but it is a very neat little setup that is very easy to install and very light. On this setup, I did everything possible to keep weight to a minimum. The plane is built according to the instructions with these exceptions: 1) No strapping tape on the fuselage 2) Only three strips of strapping tape on top and bottom of wing 3) Punched lightning holes in the tail sections
The 280 Motor/gearbox comes with a large plastic firewall screwed to the back of it. Pull the two screws out and remove it so it will screw directly onto a plywood firewall. I made the firewall just long enough to cover the back of the motor unit because the battery needed to be completely forward - under the gearbox - to balance the plane.
	This is typical of the lightning job done on the tail section. I used a 1/2" diameter punch and cut the plastic out between the holes on the main body of the stabilizer. An amazing amount of material can be cut away from the coroplast and still have it very strong. I could have actually taken more away than you see here. Another way to make a lighter tail section would be to use balsa (ughh), but it would not be as durable.
The plane is built now and the motor installed. To balance the model correctly the battery is all the way forward with the speed control above it and the receiver right behind it. The elevator and aileron servos are located under the wing, just behind the middle area. I used FMA S100 servos to keep weight down.
	Here is the completed project ready to fly. The battery is in a pocket on the other side of the plane and is slid in and pushed forward until it is completely forward under the motor. The front of the engine compartment is kind of pinched together and a little piece of scrap 2mil coroplast is fitted and taped in to shape the bottom of the nose and help support the battery. Notice the little square hole in the front "window", that is for cooling the speed control and access to the fuse. The servos exit on either side of the fuse at about the place shown on the instruction sheet. I did push them as far forward as possible because this plane turned out a bit tail heavy because the motor is so light. A speed 400 with a gearbox would produce a better weight distribution so the battery should be a little farther back. Speed 400s are mounted like the P51 example above using our Emm motor mount - very simple!

Optimizing our fomies for speed 400 electric power