Bomb Drop

For me, part of the fun of building is the ability to customize each plane, not just in color scheme but with goodies like smoke and bomb dropping. I have never had the opportunity to drop anything (intentionally) from an R/C plane and this build seemed like a good opportunity to give it a try.

So here were my goals in the approach...

[ul][*] More that one independent drop
Having the ability to make more than one pass at the target would give me a better shot getting closer and make it a lot more fun.
[*] One servo
So the trick is how it have two independent drops without the added cost, complexity, and weight of two servos.
[*] Flexibility
I'd like to be able to drop different thing like bags of flour, bomb-like looking objects, or maybe even serve as the jump plane for an R/C parachute figure.
[/ul]

So with a loose set of requirements, this is what I came up with. A recessed compartment is built into each side of the bottom wing. Keeping with the flexibility idea, I decided to go with two pins holding whatever it is that I will be dropping. Guide sleeves were glued into each drop assembly. Then separate control rods were used with pins engaging the guide sleeve. The other ends of the control rods were attached to each other and then attached to a clevis to be connected to the servo arm.

A compartment in the wing for the bomb drop servo was framed up out of scrap . A one sided servo arm was used. Two holes were drilled into the arm so that both control rod clevises could be connected without interfering with each other.

I used the three position switch on my radio for control. When the switch is in the center position, the pins are positioned on both sides so that they go through the sleeves, through the objects to be dropped and then engage the opposite side of the drop assembly. When the switch is thrown in one direction, the pins on one side are retracted just enough to drop the object but on the other side, the pins engage further and therefore still keep that side from dropping. When the switch is thrown to the other direction, the pins are retracted from the side that still has an object and so it is now dropped.

Since I'm not sure what all I will be dropping, I added a block with blind nuts to the rib next to the drop assembly. This will be used to hold down a strap that will hold the object and be engaged by the drop pins. Because something may be held to the wing between the ribs, I also added some balsa sheeting between the drop assembly and the nut block. This is so what ever is being held is not being held against just the covering.

Next, the Upper Wing...