A paper plane shooting device from a single NXT set
About this creation
NXTPlaneShooter is a device i created to shoot paper planes and was build from a single NXT set.
MIND YOU this may not be a toy anymore, depending on the rubber spring!
NOT TO BE USED BY KIDS WITHOUT PARENTAL SUPERVISION
The heavy NXT brick with batteries was chosen as a base for stability.
It exploits one motor to rotate freely, only limited by the cables, around its vertical axis, so turning left/right. Another motors controls the azimuth, meaning it can aim low of high. The third and final motor is used to charge a rubber spring and shoot away the plane, besides doubling as a counterweight.
The motor has 2 winches with 2 ropes for pulling a puller along the boom in both directions. The mechanism operates as follows:
1 the puller slides towards the free end of the boom,
2 where it engages with a shooter, sliding two hooks over and behind two orange sloped pieces,
3 the puller slides back, taking the shooter along with it,
4 this charges a rubber spring tied to the shooter,
5 the puller slides back until the button detects it is ready for firing,
6 a paper plane is put onto the protruding pin of the shooter,
7 the NXT waits for a fire command, (for example shouting at the microphone, or someone getting too close, or someone turning on the light entering the room...)
8 the puller slides back just a centimeter or so,
9 thereby two rollers spreading the two hooks by rolling over two other orange pieces,
10 hence releasing the shooter,
11 the rubber spring does its work, the shooter shoots forward accelerating the plane,
12 the shooter stops at the end of the free boom, cushioned by rubber,
13 the plane continues in the shooting direction.
To see how it works in practice please have a look at the YouTube movie !
You can find build aloing with the slideshow on PhotoBucket. Please pause/play and build along as you wish.
As of 20090905 I tried once more to reorganise the pictures in the right order. It seems to be ok now, but some pairs of two neighbouring photos may still be swapped. So it seems advisable to look ahead one photo if you get stuck, just in case two were swapped.
You need to be aware that the NXTPlaneShooter requires manual operation, or you can write your own program for it in the LEGO visual programming language (NXT-G). Take care not to snap the ropes!
First i programmed a NXT-G program that retracts the puller until it hits the button, waits for sound input and then retracts it further a fixed amount of degrees (depends on your winch, diameter of tube) to release. Then it moves forward a fixed amount to engage the puller with the shooter again, and retracts the puller until it hits the button, which completes the cycle.
Azimuth and elevation maybe controlled anyway you like, for the YouTube movie i operated it manually with the joystick utility of the BricxCC command center using BlueTooth.
The paper plane has a staple in the front, ensuring that the plane moves along with the accelerating grey pin, otherwise the paper may just glide through the slit in the grey pin.
Apologies for this late addition:
The green tubes are... green tubes indeed!
It is supposed to be used for an aquarium, i think this one is 12 mm diameter outside.
Just take LEGO gears and an axis, to be sure you will get the gears out the tube again!
Shop for say 1 meter of tube that fits snugly around the 8 tooth gears for this model, or any other gear you have in mind for other models.
Alternatively, there is a LEGO solution with a piece for winding a rope onto, but i do not have that, and it is not in the NXT set either.
Still alteratively, consider using an axis extender instead of the tube-over-gears.
Either way, you want to arrive at something smoothly cylindrical with sufficiently large diameter. Good luck!