This page will be dedicated to the construction of a REMOVABLE bomb drop system for any of the Parkzone and many other FOAM airplanes.

Materials Needed:

 10mm or 3/8 X 3/8 motor stick or equivalent approximately 5" long

5/8 or 3/4 wide base plates (I used wide tongue depressor type sticks from Wal-Mart) approximately

Wire - As thin as you have - a straightened paper clip CAN be used but music wire is preferable

Several straight pins.

Roll of packing tape. I used the clear type as it will need to be painted later.

3/4" thin wall sprinkler pipe

CA glue - thick and thin

Gorilla glue - big bottle brown color

Water - spray or mist bottle preferred but not really necessary

Drill and/or dremel tool Needle nose pliers. Cutters. X-Acto knife.

2 sets of control horns - small and as inconspicuous as possible! LOL!!

8 rare earth magnets (you could probably get away with using 4 if you have to.)

Begin Construction

First cut two 2.5" lengths of the 10mm or 3/8 X 3/8 motor stick.

Then drill several holes near one end and route them out to create a slot which runs through the stick.
The slot need only be big enough for the wire to pass through easily without resistance.

Next make a groove from the end of the stick NEAREST the slot to the slot in the bottom of the stick.
The groove need only be deep enough that the wire can move along it freely after the stick is glued to it's base plate.
The 10mm or 3/8 X 3/8 stick then can be "shaped" using a sanding drum and dremel tool or
regular sandpaper if you want so that the side opposite the "grooved" side has a slant. This will give it the appearance desired
when mounted of a hard point on a regular plane.

Once the shaping is done the wire needs to be bent to shape. I used a "z" bend at the control horn end to make it easily removable
but I suppose you could use any connector type you want. There needs to be about 1" of wire from the end of the base plate to the
"z" bend. This gives plenty of room for movement as only about 1/8" of movement is needed for actuation anyway.

 STOP!! - DO NOT GLUE ANYTHING YET!!

Now place a magnet on the end of a base plate and draw a circle (or rectangle as may be) around it.
This material will need to be removed so that the magnet will be flush with the bottom of your base plate.
This can be done at both ends of your base plates as this is the mounting method. I also used the sanding
drum to "rough up" the ends of the magnets where they will be glued as this helps keep the glue in place.

Now tear off a piece of packing tape and place it STICKY SIDE UP on your bench. Place one of the base plates
that you have prepped onto the center of the tape strip. Place the magnets into their place (the tape will "hold" them there.
Now us a liberal amount of CA glue to secure the magnets in place with the base plate. Don't worry about getting CA glue
on the magnets as the tape is covering the essential mounting surface!! LOL!! Repeat for both base plates.
When the glue has set and the magnets are in place on both base plates cut the tape around the base plates as closely as you can and
use your sanding drum to remove any excess. You can now set the wire in place and glue on the 10mm or 3/8 X 3/8 stick to the base plates.
If your magnets stick up slightly then making a indent into the stick so that it covers the magnet is preferred. Make sure the wire moves freely
after the glue sets!! LOL!!

Also do not worry about the wire sticking to the magnet as it really will not be a problem.

Your top mount is done. You can check it against a piece of the thin wall sprinkler pipe to make sure it works as designed.
This is also the time to add the straight pin to the front of the mount. The straight pin is used as the front tensioner for holding the "bomb" in place.
It will need a drop or two of CA after it is in place. The length between the front pin and rear wire is totally up to you and the size you want
your bombs to be.For trial cut a piece of the pipe and use the pin placement for reference to drill two small mounting hole into the pipe.

Keep in mind that the REAR hole on your actual bomb will need to be as far rearward as possible.
The reason for thins is that after you add the fins to the rear of the bomb it must still "clear" the flap!
The bomb is "trapped" by the pulling of the wire rearward by the flap and thereby "trapping" the bomb
between the wire hook and the front pin. When the flap is actuated and pressure is relaxed the bomb
simply falls away.

Now that you see HOW it works we can start the wing mounting process.

Allow two other magnets to snap themselves to one of your base plates. These
can now be used to mark their mounting place in the wing. Make sure the wire is completely
to the rear of the slot - as it will be when the flap is up in its normal position (as it should
be for this installation!). This will give you the mounting place not only for the wing magnets
but also for the control horn on the flap. Remember you will only need about 1/8" of
travel in the wire to capture or to drop your bomb but the control horn must be mounted
so as to allow travel of the wire WITHIN THE SLOT and not bottom out at one end or
the other.

Not like this!! It won't work like this!

Once you have the position set press EVERYTHING down pretty hard into the foam.
This will indent the foam with the magnet position as well as leaving an impression. Now
cut out the impressions to allow mounting the magnets. While the magnets are STILL STUCK
to their counterparts you need to MAKE them - the marked side will be GLUED into the wing!
If you need to test fit a magnet remove one - but put it back after the test fit!

This is WHY the magnetic poles of the magnets being matched is so very important because
if you glue a magnet into your wing incorrectly it will NOT ATTRACT but will repulse!
Leave the magnets attached to the base plates until you are ready to glue them in place!!

When you are ready test fit the mount WITH the magnets still attached. If it fits tightly
and is aligned then you are ready for glue. Remove the base and keeping it aligned with
the wing - i,e, front to front and rear to rear - remove ONE magnet. It will very hard to do!
And now you will see why marking the side that will be glued was important!! LOL!!
Put some thick CA into the hole for the magnet - place the magnet into the hole with the
MARKED SIDE IN the hole - now repeat for the other end. Cover the magnets with
packing tape.

Let the glue set and while it is setting use a Sharpie (Silver in this case as these are on a
Parkzone P-47) to color the tape. The tape will also help in keeping the magnets aligned.

Now attach the control horn into the place marked earlier and you should be ready to snap on your
system and go drop bombs. Making bombs will be covered in a later build thread but they are
made from the 3/4" thin wall pipe. Thin wall pipe is the lightest so that is why I chose it.

Here is a little video demo of the system finished and working.

http://youtu.be/VnsJ6Jy9PyI

Hope this helps. I have fully tested this and it works flawlessly.

The following is a "HOW TO"for installing your bomb release mechanisms onto your airplanes wings.