WARNING
Powered
models are dangerous! All model airplanes present a certain amount of
danger to the operator and anyone in the vicinity. Please be careful when
starting the motors and use good safety practices when operating this
model. Wear eye
protection.
We
at JK Aerotech, have no control over how this product is used. You, as the
operator of this equipment assume full responsibility during the building
and flying of this model to operate it in a safe manner. Do not start the
engine with anyone, including yourself, in line with a spinning prop or
directly in front of a running motor (I have seen props come off). Always
keep hands and fingers and other body parts out of the spinning prop. Do not fly over people,
or in populated areas. BE CAREFUL!
This is not the tail used on the plane plane we are building here but it doesn't matter, they are all the same.
Set up the engine and motor mount. This one is the OS LA .15 -- great motor!
Notice two things here: first thing is the fuse doubler is trimmed to simulate the earliest B model Mustang. Basically the chin scoop is eliminated but some later B Mustangs had the chin scoop so either way is OK. The second thing is that after setting up the engine and mount, I determined that to get 1/8" of clearance between the spinner and the front of the fuselage doubler, I would have to place the back surface of the firewall 3" from the front of the doublers.
This
is the new pattern and firewall wood that comes with the new kits. The
centerlines mark the position of the center line of the prop shaft. The
circle and the four small holes mark the position of the Slickmount ll if
that is the engine you want to use.
For specific Slickmount instructions, click here
Very soon we hope to have the firewalls CNC cut to the exact
size and shape. If not, we will supply a chunk of plywood and a pattern
for you. I kind-of got the cart before the horse here and sanded the fuse
round before trimming for the firewall. You will have to lay out the
engine and mount you are using and trim the front of the fuselage so that
the firewall, mount, and engine combined will position the prop and
spinner to clear the front of the fuselage doubler. This is much easier to
do before the fuse is sanded. When you cut the nose, be sure not to change
the firewall angle. The face of the firewall should be perpendicular to
the wing and tail centerlines with no up, down, or side thrust. Use
the pattern to cut a firewall to shape from the plywood provided, then
mark the center line on the firewall.
Our fuse is intentionally left a little long so that you can fly this plane on our Slickmount and a Norvel .061 or electric power. For the Slickmount you would have to drill a 1-1/4 inch hole in the fire wall at the correct height so the spinner would match the front cowl. We have a center line drawn on our pattern to line up the .15 motor mount or the Slickmount. For tips on how to set a plane up with the Slickmount, see the additional instructions below
Another big NOTE here is that if you use our Slickmount 2 with a Norvel 061 or 074, you will not need to cut anything off the nose as it is sized for that combination from the factory.
We have determined that (on this particular motor / mount combination) the back of the firewall is to be 3" from the front of the doublers so set the fuse on one of the doublers and draw a line on the doubler showing the front of the fuse.
Now measure the difference between the 3" mark and the front of the fuse and this will tell you how much to shorten the fuselage for this particular engine. In this case the difference was 13/16 so mark a line on the foam fuselage that measures 13/16 " from the front and draw a line parallel with the nose of the fuse. Notice that the protective foam side skin is between the table and the fuse. This keeps the fuselage center line horizontal to the table.
Now whack the front of the fuse off and your engine/motor mount setup should come out just right! If you took a little too much off, no problem, just trim a little off the doublers for prop spinner clearance. Try to get the cut parallel to the nose and perpendicular to the table when the foam side skin is on the fuse.
The fuel tank is laid out and cut in at this time. I like to go in from the left side of the fuselage, at about the center line, and dig a pocket that fits the tank snugly with about a 3/8 inch of foam left behind the firewall for strength and cushion in case of a crash. I like to crowd the tank close to the left surface of the fuse to give me a little extra foam on the right side to make a tunnel for the throttle servo without accidentally boring a hole into the tank.
You will have to accommodate the lines coming from your particular tank and a good way to help everything slip into place is to make the pocket long enough so that there is a little space for the fuel and vent tubes at the front of the tank area. After slipping the tank in, cut a chunk of scrap foam to wedge the tank in and keep it from sliding forward and possibly pinching the lines. Locate and drill holes for the fuel and vent lines and install the tank.
Glue the firewall on with 3M77 or epoxy and cut off the scoop under the wing.
This is one of the other modifications for the B model Mustang. The fuse doublers are punched for the D model bubble top canopy so lay the doubler on the side and mark it as shown and trim it off. This one is going to be an early B model so I trimmed the chin scoop off also
You should now have a sanded fuselage with a firewall and tank installed so the next step is to glue the fuselage doublers on. These are cut from 2mil coroplast material and will cover each side of the fuselage from about the back of the wing forward and will be long enough to make the side of a cowl. If you miscalculate and get the engine a little to far back, it is easy to trim the nose a little to make it fit.
The next series of pictures show the fuse doublers being installed with the tank access door and top and bottom filler pieces. This is all explained in detail in the text to the right so study the pictures and pour over the instructions.
Use 77 spray glue to stick the fuselage doublers on and be very careful to line them up to the wing saddles on each side. Now you will see why you scored the inside of the doublers. They should conform rather nicely to the contour of the sanded fuse and if you let the contact cement dry well, should mould themselves to the nose. You should also begin to see the shape of the lower edge of the cockpit. Spray a light coat of 77 spray glue over the rest of the fuselage and let it dry.
Bottom filler piece. Again, you won't believe how strong this nose is until you hit another plane or the ground.
It is hard to see, but if you look closely you will notice the trap door for the tank access.
Since the fuselage is sanded to shape, including the under wing scoop, you can cut the scoop off now to allow the installation of the wing. The scoop will be covered and re-attached later on after the wing is installed.
Great shot of the tank installation.
A little close-up of the engine mount and fuel tubes. The bottom one is the fuel line to the carb and the top one will go to the muffler pressure tap.
We have included some extra 2mil coroplast with the kit. It will be the left over stuff from the sheet the doublers came in. This will be used for fill between the fuse doublers on the top of the fuselage nose from the firewall back to the canopy and the under belly from the firewall to the front of the wing saddle. You will end up with a nose section that is completely covered with coroplast. If you are really tricky, you could make the bottom one long enough to fill out the bottom of the cowl to make the chin scoop at the nose of the plane. After it's taped up with strapping tape and the colored packing tape, it will look pretty good.
After fitting the extra 2mil coroplast top and bottom, glue them on with spray glue. Use a hand tacker or staple gun to staple through the coroplast into the edge of the firewall all the way around. This will make the firewall very solid and able to withstand unbelievable crash forces. If you don't have a staple gun, use 1/2 inch wire nails, upholstery tacks, or even thumbtacks. Just be careful that you don't drive them through the fuel lines, if you have already installed them.
Before proceeding with the taping, spray another light coat of 77 spray glue over the foam part of the fuselage and let it dry.
Notice that the doublers have a little slot just ahead of the leading edge of the wing saddle. You will want to keep these from being buried and getting lost, so as you start taping, always identify the slot or cut the tape out of it as you go along. These are for the inboard wing chines that will be installed after the wing is on.
The second major key to the strength of our planes is to wrap strapping tape around the nose from the firewall back to the canopy. Do the same on the under belly from the wing saddle to the firewall. Lay the strips side by side and pull them hard enough to cinch the coroplast down tight to the foam. I use long enough strips to go over the top and down the sides about half way then turn it over and do the belly the same way. I like to do the same thing with the wing saddle. Lay strips of strapping tape side by side and cover the whole wing saddle and let the ends run up the side of the doublers about an inch. Pull these tight as you put them on too.
When strapping tape is wrapped radially around the nose and wing saddle, you will make the nose of the plane virtually unable to crush or buckle. The strength of this construction will be evident on the first ground plant.
The extension at the front of the fin is called a dorsal fin because it extends along the dorsal area of the fuselage. For stability reasons, the real P51 D fin was changed and a dorsal fin was added. The earlier B model usually did not have a dorsal fin on the tail so trim this off by drawing a line along the front edge of the fin to intersect a line along the fuselage. Put a small radius between the two lines and cut that part of the fin off.
After the strapping tape is wrapped around the nose and wing saddle, it is time to remove the canopy. Use a sharp razor knife to slice it off all the way around until it comes off. The fuselage doublers and the filler on top of the nose define the canopy pretty well but you will have to adlib a little at the back of the canopy.
After slicing it off, set it aside as it will probably need to be hollowed out a little to clear the servos before covering it with tape. It is helpful to smooth the interior area foam where the canopy came off with sand paper. This will make a smoother surface for the radio installation and fuse taping.
The place to start is at the wing saddle. You should already have strapping tape covering the saddle from side to side so now we want to cover it with color. Start at the trailing edge of the saddle and lay packing tape across the saddle letting the tape run up the side of the doublers an inch or so. Keep laying in strips of tape with about a 1/4 inch overlapping the preceding strip until the saddle is completely covered.
TIP:
when trying to tape a curved fuselage surface with packing tape it will
tend to bunch and pucker. Stick the tape along the flattest surface and
slice the edge that is hanging over about every ½", then starting at
the back, working forward, smooth each little flap of tape over the curved
edge. The little flaps will overlap each preceding flap and the curve will
be much smoother. After the fuselage is taped up, use a razor blade to
open the wing slots and wrap the excess tape flaps into the slots.
Notice how the wing scoop area is left uncovered.
Notice also the tape is long enough to wrap over the front of the doublers. This will cover the engine compartment up to the firewall. Then use as much tape as you need on the firewall from top to bottom. This is to seal the firewall and keep oil from leaking between it and the doubler.
After the saddle is covered side to side, you can cover the fuselage. First lay a strip of strapping tape along each side from the nose to the tail then start laying strips of colored packing tape on the fuselage from front to back. I like to start on the bottom and work up the sides. Overlap the preceding strip by about 1/4 to 1/2 inch until the whole fuselage is covered. Use the tip outlined above to help the tape conform to compound curves, unless you like lots of wrinkles. If you make lots of slits to help the tape conform, it is sometimes good to lay another strip of tape so that the previous slits are covered -- even if it means overlapping the strips of tape an inch or more.
If your plane will use the doublers to make the cowl, it is a good idea to let the tape run long enough to tape around the front of the doubler to cover the inside of the engine compartment all the way back to the firewall. After the fuselage and engine compartment is covered, lay vertical strips of tape on the firewall, from top to bottom, to seal it.
Since the Mustang has the belly scoop cut off, you will have to leave that area uncovered until the wing is on and the scoop is glued on.
Well that about does it for the P51 B so from now on the construction is the same as the D model so go to it! The next section is the wing and it is the same on all Mustangs. The only real note here is that if you intend to fly with electric or Norvel .061, you will not need to add so much tape to the wing center area. Several strips of strapping tape to the spar area on top and bottom should be enough unless you will be packing around heavy batteries and a Cobalt motor, then you might need the extra tape. But if you use a geared speed 400 and 600mah battery pack, the lighter the better.
This fuse used our black tape for the front deck. You could use black electrician's tape to get the same affect.
I know I didn't install the tail like I say to, I did it just after the wing was finished but there is no reason not to do it now. Besides, It will cure nicely while you are taping the wing together.
At
this point you should have a fuselage that is completely taped up except
for the belly scoop area. The tail group should be dry and ready to
install now. I use a coat of 77-spray glue on the part of the tail that
slips into the fuselage. Now, you have to be fast so have the slot in the
fuse open (slice along the covered up slot and push the excess tape into
the slot) and ready to receive the tail group. Then, quickly spray a wet
coat of 77 glue on the parts of the tail that fit into the fuse. Before
the glue starts to set, slide the tail into the slots of the fuse. Make
sure the fin is straight and true with the centerline of the fuse and
squish the sides of the fuse onto the fin. If you are not careful, it is
easy to give your plane a permanent right or left turn by bending the back
of the fuse one way or the other. The goal here is to assemble the tail
group and fuse while the glue is still wet to allow a little slippage so
they can be aligned properly---good luck, work fast! Apply a strip of
packing tape under the fuse to close up the tail slot, then run a small
bead of Goop on either side of the fin to stick and seal the tail to fuse
joint. Block the fuse and tail so they will cure in good alignment.
You
should now have a completed airframe ready for radio gear and wing
installation!
After the wing halves are stuck together, run four strips of strapping tape from wing center to each tip, top and bottom. Dihedral wings are hard to do in one length so I start across the center section to each tip. Use a slight stretch on the tape. If the wing panels are bowed up or down, pull harder on one side to correct the bow.
After the strapping tape reinforcement is on, use the colored packing tape and tape chord-wise from the center out to about 10". overlap each successive strip of tape about 1". Do that top and bottom and let the ends of the tape wrap around to leading or trailing edge to the other surface about an inch. The main idea here is to use lots of tape to beef up the center of the wing because the wing takes the most stress from the joints to about 10" out the wing panel.
Note: If you will be using Norvel 061 or speed 400 electric, you can cut the amount of tape down. Use two strips of tape tip to tip for the spars and leave off the the extra strapping tape steps above. Just use the colored tape from the center out about 10" and overlap about 1", as above. This type of power will make a very light plane and the wing can be built much lighter..
After
applying the strapping tape to the wings, it is time to prepare the
ailerons. Cut the ailerons from the elevator sheet. make the ailerons
about 1/2 to 5/8 wide. The ailerons are just right if you slice the
coroplast so that two complete ribs remain with half a rib left on each
side - see fig 4. Trim the outboard ends of the ailerons to blend with
the wing tip curvature and the inboard should clear the fuse by about 1/4
inch.
When covering wings with packing tape, always follow this simple taping convention: Always start at the back and work forward overlapping about 1/4". This way the tape edges will flow with the wind instead of pointing into the wind. Another good idea is to always start with the bottom of the wing so that the finished wing always has the top tape wrapping over the bottom surface. It just looks a little neater.
With dihedral type wings, it is always easier to tape from the middle out
to the tip. Start at the trailing edge and lay
the regular 2" packing tape across the wing from the middle to tip.
Let the center over lap the far seam about 1". Let the tape run long,
leave the ends stuck to the table until the surface is covered, then with
a razor blade trim to about an inch long and fold around the wing tips
before covering the opposite side (this gets a
little difficult when taping the bottom of a dihedral wing so I lay the
wing upside down on the edge of a table with half the wing hanging off the
table, then work on the half that is supported by the table).
TIP: when trying to tape around a compound curved surface like wing tips with packing tape it will tend to bunch and pucker. Before pulling the ends over the wing tip, slice the edge that is hanging over about every ½", then starting at the back, working forward, smooth each little flap of tape over the round edge. The little flaps will overlap each preceding flap and the curve will be much smoother.
Again,
always apply the tape from trailing edge to the leading edge with the
typical ¼" overlap. The leading edge should have a couple layers of
tape wrapped around it by the time the top and bottom covering is done. We
recommend adding another layer or two of tape to the leading edge for
extra protection. Stretching the tape modestly while sticking it down will
help it go on smoothly but be sure to balance the stretching or you could
have a wing that bends up or down.
The control throws should be about 1/4" up or down. This will make the plane very easy to control at high speed.
After the servo is cut in and you are certain of it's placement, slide it out for a second, coat the edges of the foam pocket with silicone and slide it back in place. Wipe the excess off and be careful not to get it on the fuselage or wing where more tape would go.
Hold the wing to the wing saddle in the fuse and eyeball where and how much clearance you will need to cut into the wing saddle for the servo. You will have to cut a hole in the fuse doubler for the pushrods to exit the wing saddle and there will have to be enough cut out so the servo arms and pushrods will work without binding on anything.
It is a good idea to hook the servo to your receiver to check for correct and smooth operation because the wing will be glued on permanently very soon.
The radio gear will be mounted under the canopy so bore a 1/2 hole through the fuse to route the aileron servo from the wing saddle to the canopy area.
Notice this plane is balancing on sharpened pegs. Here's an easier way to balance it: Don't turn it upside down, just mark the balance point on each side of the fuselage and grasp it, between your thumb and forefinger. With practice, you can tell pretty well if it is balanced OK.
This is the cockpit layout for this P51, notice the receiver in upper right. Just below that is the FMA S80 throttle servo in the lower right. To keep the weight down I used our BA 350 battery pack, upper left and an FMA S100 servo for the elevator, bottom left. The switch is sideways on the left. Here is a good tip: DON'T USE A SWITCH!! You will see the results of a midair further down this page in which the jolt from the hit turned my radio off. So, from now on my combat planes will have the battery plugged directly into the receiver with a trap door or something to open for access to the receiver plug.
This
is a starting point and can be shifted fore or aft a bit. Use the battery
and radio gear to adjust the balance point and add a little weight if
necessary. The elevator servo can be cut into the side of the fuse or if
there is room, under the canopy. Try to make everything accessible form
the canopy area. When you have determined the best positions for the
servos and radio, turn the plane over, then, keeping them in about the
same linier place, mark a line around them and use a knife to cut
the pockets in the foam. Use a gouge to dig the pockets out and be sure to
keep the fit as snug as possible. Find a convenient place for the switch.
Make a hole for it or cover it with tape and use a piece of piano wire to
operate it. Leave the charge cord accessible also. After the pockets are
cut, if necessary, bore a hole from pocket to pocket to route wires
through for a neat looking job. A 1/2" diameter tube sharpened on one
end works great.
Servo
installation
Thread the wires through the holes and hook up the plugs. Now is a good time to center each of the servos and make sure of the control wire lengths. Before sliding the servos in for the final time, coat the pocket sides with silicone sealer. This will hold the servo in place and the silicone is not too impossible to remove. Try not to get silicone on the plane because tape will not stick to it! If you do, wipe it off with mineral spirits (paint thinner). Tip: wrap the servo with tape so the silicone can be easily peeled off if you take the servo out. If you mount your servos externally, tape over the servos leaving the shank sticking out. I must stress again to make the servos fit snugly. If you want them to fit flush with the surface you are imbedding them in, you will have to create a pocket that is sort-of two stepped to clear the mounting flanges on the servos. This will allow the servo to sink further in and will keep the control arm as close to the fuselage as possible. Another great idea is this: If you intend to do a lot foamie plane flying, just cut off the servo mounting flanges and sand the bumps smooth. This will allow the servo to slide down into a nice, neat, straight-sided pocket. Of-course you won’t ever be able to screw the servo down again, but if you get into foamies, you won’t ever need to!!!
The
control throw for the elevator is 1/2" up from center and 1/2"
down. This will make a very quick turning plane so you could cut that down
for a more docile handling aircraft.
While the wing is curing, the canopy can be taped up and fit. Since the radio gear is installed, you will probably need to carve out some clearance for servos and other gear so the canopy will fit. Set it aside as it will be the last thing to install just before flying.
It would be entirely OK to leave off the chines as the latest model mustangs did not have them.
Now let's get back to the chine installation. The parts are funny little pieces on the 2mil coroplast sheet. You should have four little horseshoe shaped pieces with tiny slots in them, these are the Root Formers, and a long skinny triangle with tabs, these form the leading edge of the chine. Notice two of the Root Formers have the coroplast ribs running lengthwise and two have the ribs running across the part. I thought this might make the Root Formers stronger so take two with opposing ribs and glue them together with CA or 5min epoxy or Goop, MAKE SURE THE LITTLE SLOTS ARE LINED UP. Do the same with the other two Root Formers. Now you should have two Root Formers that are double thickness. These will go, one on each side of the fuse and they will fit with the tiny slots lined up with the slots in the fuse (the ones that you should have kept open - remember?). Don't glue them on just yet though! First, make sure the tab on the end of the Chine Former fits into the slot in the Root Former and the slot in the fuse doubler. You may have to use an X-acto knife to open them up a little. Temporarily fit them together and stick them into the fuse doubler. They probably won't fit exactly but don't worry, just slide the Root Formers over the leading edge of the wing and stick the tab into the fuse. Now you will have to cut a little slot for the tab on the pointed end of the Chine Former to stick into the leading edge of the wing. See fig 6.
This is a close-up of how the chine covers look after they are covered with packing tape.
After you are sure the covers fit properly, use spray glue and stick them to the wing, top and bottom. The under side may have a little gap at the fuse, but that's OK we are going to tape it up in a bit.
I taped a scrap piece of coroplast in for a chin scoop and a strip of tape across the top of the nose just behind the spinner to help give the illusion of a cowl.
The canopy can be painted gray or silver with Krylon spray paint and decorated with automotive pinstripe. I sometimes use 1/4 inch black pinstripe to hold the canopy on around the edge or you can tape it on with clear or colored tape and touch it up with silver paint.
You can decorate it with different tapes or decals. I like invasion strips made with two strips of white packing tape and three stripes of black electricians tape. If you have a computer and a drawing program, make up some stars and bars and stick them on the wings and fuse with spray glue then tape over them with clear tape.
The main thing is to have fun with this plane. This is designed for a .15 size 2 stroke but a Norvel 061 or geared 400 electric would fly it nicely also. We have customer that are flying .40 engines with tuned pipes.
You can go now to our original instruction set that shows how to install the Slickmount and 061, or to the electric conversion.
Notice the intact airframe! This plane is tough! The impact with Ralph's plane took the invasion strip off the left wing. This is also a great testament to Grish Products flex props, this prop was folded back against the side of the motor, but it didn't break!
A little tape and you will never know it had been crashed. I love Styrofoam!
Cad
drawings
Pattern for the chine cover
This is a segment of a previous version of P51 instruction set that outlines how to install the Slickmount into the fuselage. This would be pretty much the same on any of our kits that are the right size for 1/2 A power.
