mechanical ballistic computer [updated]

[davidz40]

Inspired by conundrumer's ballistic computer, I created this:

ballistic computer

davidz

Rating:
Filesize: 37.52 kB
Comments: 4
Ratings: 9

here's new one:

Ballistic computer beta

davidz

Rating:
Filesize: 53.6 kB
Comments: 7
Ratings: 12

Not so sophisticated and not super accurate, but I like simplicity

[Paradigm 29]

If you have a problem with consistent initial velocity then just use a spring bullet. Those always expend a measured amount of energy whereas superbouncy reactions can be more or less powerful depending on the speed that the projectile hits the high restitution surface.

[davidz40]

actually I use repulsion instead of superbouncy to get better precision, but I'll switch to spring bullet. Thanks for advice. I'm actually trying to measure shot height too, but for now, I don't know how to "calculate" sina*sina (or any other expotentiation)

[KarateBrot]

[...] I'm actually trying to measure shot height too, but for now, I don't know how to "calculate" sina*sina (or any other expotentiation)

I will deduce the "formula" for you. But first... I have to play Wii Sports Resort

[Paradigm 29]

The position function for a falling object is -1/2at^2+Vit or -4.9t^2+Vit.
Since Vi is also a known constant (after you get better bullets) the velocity function for the falling object is -9.8t+Vi.
If you want to get the Y distance then you'll need to use this: -9.8t +Vi*Sin(theta)
Plug in whatever Vi you got and set the equation to 0 (for example say Vi=100 and let (theta)=30 degrees). It should look like:
-9.8t+100Sin(30) = 0 which simplifies to
-9.8t+100*1/2 = 0
-9.8t+50 = 0
9.8t = 50
t=50/9.8

So, if your cannon is pointed 30 degrees above the horizontal and is shot from the cannon at 100m/s, then it will take 50/9.8 seconds (decimal is ~5.1s) for it to reach it's highest point. Now lets go back to the position function!
-4.9t^2 + Vit or -4.9t^2 +100t
which, according to the time it took to get to the highest point (5.1s) is:
-4.9(5.1)^2 + 100(5.1)
= -127.4 + 510
= 382.6

So, your maximum height would be 382.6m
The equation for the maximum height achieved on a projectile curve again is:
y = 1/2*a*{[Vi*Sin(theta)]/a}^2 + (Vi*Sin(theta))*{[Vi*Sin(theta)]/a}

=3(Sin(theta))^2 * Vi^2 / 2a

Wikipedia or some other internet site could maybe give you a method that requires less inputs.

How do you do that mechanically? I don't know. I do know that Conundrumer used a Sine generator which is basically the wood mechanics scene. Really though, it's probably going to be beyond most of us normal people to figure that out by mechanical means.

[KarateBrot]

How do you do that mechanically? I don't know. I do know that Conundrumer used a Sine generator which is basically the wood mechanics scene. Really though, it's probably going to be beyond most of us normal people to figure that out by mechanical means.

i would say he wants it mechanically because he knows the function for the trajectory parabola, i guess, because he calculated the maximum distance with it. and he also said he doesn't know how to do an expotentiation with sin²a. the formula for the maximum height includes sin² so i think he knows the formula which is y = v²sin²α / (2g) by the way.

[Paradigm 29]

ah, sorry, well. Perhaps you could use 2 Sine generators whose outputs are connected to an analog multiplier?

[KarateBrot]

ok you're right davidz it's very tricky but i have a few ideas.

[Conundrumer]

QED
This also might be helpful:
http://upload.wikimedia.org/wikipedia/c ... -trig6.svg

[KarateBrot]

QED

that's the formula my ideas are based on
but there's a probability of i would say 70% that i will fail

[EDIT]
There you go

Mechanical sin to sin² converter

KarateBrot

Rating:
Filesize: 42.98 kB
Comments: 0
Ratings: 1

Does this example help you with sin² ?

[davidz40]

I didn't expect so much feedback
Example helped me a lot, I totally forgot that sin2 can be trasformed such way that no expotention is needed .

Now I'm going to create ultra-complicated mechanism that takes air friction into account lol

BTW what's the advantage of c-gears over standard ones?

[Paradigm 29]

C-gears always have constant contact. That means they are less likely to slip under large amounts of torque and are more accurate than the default gears.

[davidz40]

Ballistic computer beta

davidz

Rating:
Filesize: 53.6 kB
Comments: 7
Ratings: 12

I made it

[KarateBrot]

cool i really like it

[Tank2333]

wow nice
and its far smaller than con´s

[KarateBrot]

Now I'm going to create ultra-complicated mechanism that takes air friction into account lol

holy **** this would be an incredible complicated and complex mechanism. if you success you're god