pic: 1251 Prototype v 1.2



Phase two of the prototype. The ball went 37 ft and was at a approximately 30* angle. First one to guess (calculate) how fast the wheels were spinning within 50 rpm will receive a prize from the TechTigers.

Phase two of the prototype. The ball went 37 ft and was at a approximately 30* angle. First one to guess (calculate) how fast the wheels were spinning within 50 rpm will receive a prize from the TechTigers.

Here is video of it.

http://media.putfile.com/Prototype-v12

1290 rpm? Looks good guys.

My Guess is ahh 1050 RPM, I think I’m closer than I originally thought.

I’m not a mechanical guy, so it’s hard to pick out those sprocket sizes, but I’ll go with about 1665 RPM. :rolleyes:

Nice prototype, remember safety FIRST!
(How about fuse/breaker and at least a switch away from the shooter)

What kind of accuracy can you get over that range? Can you make 10 in a row into the goal?

My guess would be around 1800 but its hard to tell becuase of the sprocket sizes, my guess would be the big one is around 40-50 teeth probably maybe even 60 and the small one around 10-20ish maybe…

1750ish…

Wetzel

We made about 5 or 6 shots and they all hit the ground in about the same spot.

In my opinion it is very accurate.

Nice shirt kid in the background :wink:

Very nice idea. I think it might be a winner.

About 1775 rpm?

I have to say this seems to be the best way to shoot because the 4 wheels help guide the ball to the needed derection and the constant motion allows balls to pass though as fast as need. seems to be going 4m/s? maybe… so i don’t know any calculations for that but…2,329rpms?

really nice guys !! working pretty hard huh…

Well…I finally made it back to Chief Delphi after being away for so long.

The sprocket size should not matter at all to answer their question. They asked how fast the wheels were spinning, not the motors. With an angle and distance you need the size of the wheels and possibly height of the arc of travel to find the rpm of the wheels to launch one of the foam balls that far.

Without calculations I will guess that the wheels are spinning at 1,900 rpm.

The size of the wheel has nothing to do with the RPM of them (Unless you say that their mass slows down the system). If we know the output speed of the Kit gearbox, and we know the ratio to the the wheels, we can, with some error, find the RPM of the wheels. Now, if we were looking for the linear speed from a reference point on the wheel, then wheel size would matter.

Who says the trannies are running at full power?

EDIT: im now guessing your team number ;p 1251.

You couldnt find out the rotational speed from just projectile distance, becausethis would require the assumption that 100% of the wheels energy is translated into the ball (a horrible assumption).

That is not true. You could assume whatever efficiency of energy translation you want, but whatever number you use would be an estimate without knowing other information. You also have to estimate a few otehr numbers. But tehy gave you the angle and distance traveled.

Thats one of the easiest assumptions. They’re running the motors straight off of the battery, so the speed of the output is defined only by the battery voltage. Its rather easy to say that they were running a fairly charged battery; most people don’t run a battery to nothing and then use it to power a launcher. An easier assumption than the estimation of the size of those two sprockets.