Instruction set for Pocket Planes P51 Mustang

Notice: this page includes the complete text of the instruction sheet that is sent with the 1/20th scale P51 plus lots of pictures to aid you as you build our plane. The captions for some pictures include links to our generic instruction set for our foamie warbird to help clarify a point. This page may take some time to load but if you need help--it could be worth the wait.

At the bottom of the page is a special section by John Kim and the slope conversion he did on the Pocket P51. click here to go to it..........

Construction will be basically the same as outlined in the generic construction sheet text but there are a few things that will need to be done differently. Read both the main instructions and this addendum before starting. After doing one foamie—you will be an expert foamie builder and probably be able to throw the instructions away!

Prepare the tail group as per the main instructions. The hinge line for the elevator can be established by counting forward 6 to 7 ribs from the trailing edge. Then prepare the hinge as per the main instruction sheet.

Here is a side view of the hinge line in the elevator. Find the approx. hinge line by counting forward 6 to 7 ribs from the trailing edge. Since the elevator is tapered, count forward from the back edge near the center of the elevator. The more ribs you count the more sensitive the elevator. After finding the rib where you want the hinge, slice only the bottom surface of the coro-plast. Then trim the flashing off so the hinge will bend up and down without binding on itself. Notice the cuts in the hinge, this makes the hinge bend easier. I take an exacto knife and make 1/4" cuts every 1/4" or so.

The tail pieces are glued together with GOOP. A small bead top and bottom will do. Then block them so they will dry straight and perpendicular. CA glue will work also but will not be as crash resistant.

First off, this is a very tiny plane. So you will need to think small! In order to fit all the radio gear, you will need a small radio and micro servos. We use an FMA Tetra with S-90 servos and a miniature battery pack. Some Futaba 2 and 4 channel radios are small enough also. It is designed specifically for our Slickmount because it’s the only easy and practical way to power this pocket rocket. We should have available all the small stuff you would need. You could aso use a Cox Baby Bee, Black Widow or similar engine setup.

First you will want to shape the foam. Round the fuselage aft of the wing with sandpaper, tapering the sides and smoothing them into the canopy. Look at a picture of a P51 for a rough idea of how the contours should be. I like to round the canopy out and sand the nose to a semi-oval shape. Don’t curve it in too much at the top and bottom or the Slickmount won’t fit. Fallow the main instructions on how to make the firewall and drill the hole for the Slickmount at 1 1/16" from the top edge (Original Slickmount, Slickmount II drill center at about 13/16). Also, do not sand a compound curve into the nose. In other words, looking at the top view of the fuse, notice the fuse is straight sided from about the back of the wing forward—do not change that. Just round off the top and bottom edges. The fuselage doublers are cut so they will bend and follow the shape you sanded into the nose, see fig.#3. You can really exercise your sculpting talents here. Don’t sweat it, it will fly just great even if you cover it the way it comes in the box. Just looks a little chunky. Make sure all the fuse is sanded so the tape will adhere. Follow the fire wall, doubler and taping instructions on the main sheet with one exception; you could use ½ inch wide strapping tape instead of ¾ or 1". Also you don’t need to cover the whole front of the plane with strapping tape. The colored packing tape is sufficient. Make sure you cover the pad where the tail group sits very smoothly with no wrinkles. The excess tape at the wing slot can be slit and turned into the slot.

Now glue the tail group onto the plane using the technique in the main instructions but first run a small bead of Goop on the pad where the elevator sits then squish it together and hold or clamp it making sure it is square and straight.

The following set of pictures will take you through the firewall construction and fuselage taping procedures

	First sand the fuse to the shape you want then trace around the nose for the firewall on a suitable piece of plywood. 3/16 works good.
Then mark the center of the hole for the Slickmount (if you don't use our mount then disregard the rest of the hole drilling instructions). If you are using the Killer Bee type Engine with our original Slickmount, Measure down about 1" from the top edge for the drill center. If you are using our Slickmount II with a Norvel or Cox Tee Dee, measure down about 13/16 or so from the top edge. Kind of eye ball the thing to get it where you want it. The idea here is to get the prop shaft to come out on the centerline of where the spinner should be according to the fuselage doublers.
	I use a drill press but a hand drill will work. Just be sure to clamp the piece securely. The hole is drilled with a 1 1/4" spade drill bit. You could use a hole saw or Forstner bit as well.
Band saws work great to cut the firewall out. Watch your fingers!
	After the firewall is cut, check the Slickmount fit. If it is too tight, sand it out until it slips in comfortably. Then use the mount for a drill guide and drill the four mounting holes out for T-nuts if you want or use a 1/16" drill bit to make wood screw easy to install.
Here is the firewall all done and T-nuts installed. Notice the shape sanded in the fuse.
	I like 3M #77 to glue the firewall on but you could use 5min Epoxy also.
Lay the fuse on the workbench and set a block of wood on the top before boring the hole for the Slickmount.
	Check the fit and depth of the hole
At this point the fuselage should be primed with a coating of #77 spray glue and let dry. Then run a strip of strapping tape around the fuse on all four sides.
	Use #77 spray glue to stick the fuselage doublers on and then wrap strapping tape around the nose. The Goop was used to glue the tail pieces together. DO NOT USE GOOP DIRECTLY ON STYRO FOAM, because it will melt the foam. For more strength you can use a staple gun to sock a couple of staples through the doublers into the edge of the firewall. Assuming you use a firewall thick enough to hit and be careful you don't staple into the tank or fuel lines. This really makes the nose strong!
Start taping the bottom. Notice that the tape is sliced so it will conform better to compound curves. Make little slices in the tape and smooth each flap down working from the back to the front.
	Leave enough tape to lay over the firewall and pull over the top of fuse. The final tape that covers the top of the fuse should also pull over the firewall and down around the bottom edge also. This will then be the final seal to help keep fuel off the wood and foam.
Here the first strip of tape is applied to the side nearest you. A strip is on the far side also but it has not been slit and stuck down yet.
	Here the fuse is taped. I would suggest leaving the side tapes long enough to go around the front of the doublers and covering the inside of the doublers up to the firewall. Then the last tape on top of the fuse will seal it all off. Notice I have cut the canopy off and sliced the under wing air scoop off to allow the wing to be installed.

The wing is very simple. Follow the main instructions but since this wing is so small you can build it very light and you will not need wood spars. Sand all surfaces and round the wing tips a little if you want. Use only one strip of spar strapping tape, top and bottom and only one strip of packing tape on each of the seams, top and bottom. Then prepare the ailerons and attach according to the main instruction set. The ailerons are made from strips of coro-plast cut from the edge of the leftovers after punching the tails and fuse doublers out. Slice off about ½" wide. Tape up the wing and put one more strip of tape on each seam, top and bottom.

Since taper wings usually get thinner at the tip, I recommend slicing or sanding the trailing edge off to get an edge that will remain a constant thickness along the span. You will be cutting the ailerons from the leftover 2mil coro-plast that the tail and fuse doublers came in. So try to trim and sand the trailing edge to match the thickness of the coroplast. Notice that to get a constant thickness, you will have to trim more off as you get to the tip of the wing than at the root. In fact the thickness should be about right at the root.

Before you apply tape to the wing, sand all surfaces of the wing panels and center section. Dust off and coat with #77 spray glue then let dry. I use spray glue to join the wing panels to the center (5 min epoxy works too). Stick the panels to the center section and apply a strip of packing tape on each seam and one in the center, top and bottom. Be very aware of the wing panels and their relation to each other and the center section. Make every effort to assemble the wing panels and center so that airfoils match up exactly. Most problems with a plane inadvertently turning one direction or the other can be traced to one wing panel that is skewed slightly acting as a giant aileron. Next run one strip of strapping tape along the spar area, top and bottom. Our example to the right has all of this done plus the ailerons are attached. Check the Generic Warbird Sheet for details on the aileron procedure. Notice also that the wing saddle is completely taped up. Be sure to spray 77 on the wing saddle before taping it up.

This is the basic plane ready to install the radio and motor. The color is ugly! this is tan and we don't sell much of it but I think it will be used as a base for a Camo paint scheme. Any way your war bird should look similar to this by now. The tape overlap gives the stripe look to the wings and fuse. most of the other colors don't make such noticeable striping. The tail is glued on with 77 spray and GOOP as per the instructions.

CG: 2-1/8" from the leading edge at 1-1/2" from each side of the fuselage. In other words, strike a line parallel to the fuse at 1 1/2" out from each side of the fuse. Then on that line, measure 2 1/8" from the leading edge.

This should get you in the ball park, you can adjust the CG to suit your flying style.

You should now have a wing and fuselage ready for radio gear. First, because this is a Mustang, it has an airscoop under the wing. You will have to use a sharp blade and remove it at the back of the wing saddle (this is after the fuse is taped up). Now cut a hole for the aileron servo in the wing so that the air scoop will cover the bottom but as close to the front edge of the scoop as possible. Glue it in with Silicone. The Aileron deflection should be about 3/16" up and down to begin with. Then, when you feel more comfortable you can increase the deflection for quicker rolls. Hook up the servo arms to the ailerons then relieve the fuselage just above the servo so the control wires and servo arms can move unobstructed. The further you can sink the servo into the wing, the better because the exit holes in the side of the plane will be smaller. Now put the motor on, set the wing on and temporarily tape the plane together and balance the plane at the CG: 2-1/8" from the leading edge at 1-1/2" from each side of the fuselage. In other words, strike a line parallel to the fuse at 1 1/2" out from each side of the fuse. Then on that line, measure 2 1/8" from the leading edge. Lay out the rest of the gear to get a rough position and mark it. Since this plane is so small, I used a sharp razor and cut the canopy off along what I thought looked like the scale canopy line. After removing the canopy, I fit the battery and radio in and dug the pockets for them. The drawing shows roughly where they were located. Then the elevator servo pocket is cut and a hole is bored through the foam to run wires. After you know were the radio is mounted you can now glue the wing on. Make sure the wing saddle is covered with packing tape then put a couple small blobs of Goop on the wing saddle (use Goop on tape covered foam only) and pop the wing into place. Make sure it is centered and square. Use 77 spray glue and glue the air scoop back into place and use the packing tape to cover the cut line and stick it to the wing all around, in effect molding it to the underside of the wing. Turn the plane over and run a small bead of Goop along the wing to fuse joint. You can now install the rest of the radio gear and hook up the elevator. It should deflect about 3/16" to ¼". When the wing is cured out you are ready for the first flight.

	After the wing is covered, mark the aileron servo position. The dark marker line indicates where the front of the airscoop is on the bottom of the wing. Incidentally, We stock the mini battery packs and FMA micro servos and receivers used in this plane so if you need some check out our products page. Use sharp razor to slice the pocket outline then dig the foam out. Always make the servo pockets snug to eliminate any slop. Servos always have a little rubber grommet where the wire exits the case. Be sure to allow for that when you cut the pocket out.
Here the servo is mounted and hooked up. Hollow out the fuse too give clearance for the servo and make sure the arms move freely. All the servos are glued it with a dab of silicone as per instructions.
	Bore a hole for the wire and check the fit. A sharpened 3/8" tube works great to bore holes from the servo pockets to the radio. At this point I would mark the CG, slip the motor into position and spread the radio gear out to make it balance. Balance the plane upside down on a couple nails driven through a piece of plywood then tape the radio gear on to get a balance. I just lay the stuff out along the bottom of the fuse and sort of mark where they should go along the length of the fuse. As long as you keep things in about the same position, front to back, you can pocket them in anywhere on the side, top, or bottom of the plane.
Oops, I switched planes on you! This one already had the radio installed so I'll use it for illustration. These are only approximate radio gear placement. Yours may vary a bit depending on your motor and the type of radio stuff you have. Since the aileron servo can only work in a limited position, The balance will depend on where you place the elevator and throttle servo, battery and radio. Yes I said throttle servo. If you run a Norvel engine, you will want a throttle. This could be located on the side of the plane just ahead of the canopy. I will have pictures of that shortly.
	The radio pictured here is an FMA Tetra. Neat little radio--they are discontinued but we have the next generation called the Magnum available now. They are the right size for this plane and work great! Notice that it is pocketed in under the turtle deck. I have hollowed it out so that about half of the radio is exposed in the canopy area. The battery shown is a 110 mah 4.8v pack (also available) that is extremely small and will run the radio safely for about an hour. Check the links above for the different batteries available and their specs. On this plane I have been plugging the battery in directly and taping the canopy down when ready to fly, but you could install a miniature switch which would be handy. Incidentally, this plane has been flown a bunch and I have personally crash tested it. Just prior to these pictures it was drilled twice and it didn't even wrinkle!

This plane is fast! So set the controls at the minimum first and use dual rates if you have them. If the ailerons are too sensitive, a quick way to help that is to trim some of the aileron off. You could trim it straight or taper it from the root to the tip. If you take too much off, you can always cut them off and make new ones. Point it to the sky and give a toss, it should climb straight up but be quick on the sticks. I have noticed that it tends to roll left on launch. The only thing I can attribute that to is torque roll from the engine. So be ready for it or launch tipping it to the right a little. Grasp it just behind the wing and give an overhead toss. When it is coated with oil it can get rather slippery so hang on tight. I haven’t tried it yet but I have seen planes like this launched by hanging on to the fuse above the wings and giving it a sort of underhand toss up into the air. After it is trimmed out, it actually isn’t too tricky to fly and the glide is good. It only weighs about 11oz so it flies very fast on a Cox control line engine -- a Norvel should be nuts. Good luck!

We received several pictures from John Kim who converted our Pocket P51 into a micro slope soaring plane so we will show how he did this and include his comments.