Forces Generated by Spinning Weapons

I'm designing next year's chassis and I was curious what the typical amount of force generated by a spinning weapon is? One or two tons?

my weapon hit with some where in the neighbor hood of 77.8 lbs, at least according to the physics

if this helps what so ever

Alex P. HASD Bots wrote:

my weapon hit with some where in the neighbor hood of 77.8 lbs, at least according to the physics

That seems relatively low. What formulae did you use?

Since it's a spinning weapon you want to solve for kinetic energy, there's a couple different threads around here with te equations or you could just use the team cosmos KE calculator

According to it my drum had a modest 7000 joules of energy
That's with out taking the screws into account account in the MOI (.4 lbs)
This is also spinning at an assumed 17k rpm an not the theoretical 21k rpm that it's geared for

Cody wrote:

Since it's a spinning weapon you want to solve for kinetic energy, there's a couple different threads around here with te equations or you could just use the team cosmos KE calculator

According to it my drum had a modest 7000 joules of energy
That's with out taking the screws into account account in the MOI (.4 lbs)
This is also spinning at an assumed 17k rpm an not the theoretical 21k rpm that it's geared for

Thanks. So about 7-8,000ft/lbs should be a good target for FEA.

Do you guys use Solidworks for analysis? I'm currently on a student trial which won't allow stress analysis on assemblies so I have to make it into a part and then test. I'm not sure if this obfuscates the results or not but it is seemingly accurate.

I believe ours is to the high side I wouldnt go out of your way to hit it
Humdinger2 had around 4000 joules and was one of the hardest hitting bots I have seen

Cody wrote:

I believe ours is to the high side I wouldnt go out of your way to hit it
Humdinger2 had around 4000 joules and was one of the hardest hitting bots I have seen

Better safe than sorry. I just want to be sure our chassis can withstand those types of blows, at least for a while.

That's the thing anymore i believe it's better to have a boy to take a hit then one that can put another off the roof

i tend to use this when thinking of new designs. maybe this will help you
lhttp://www.teamcosmos.com/ke/ke.shtml

I actually just realized you said 7-8k ft/lbs
7000 joules is a little 5000 ft lbf so 7-8k ft lbf would be rather impressive

That's the calculator I use, I do enough math and number crunching already, I use calculators and converters whenever possible

That KE calculator doesn't work for me...

Camden W wrote:

That KE calculator doesn't work for me...

It was really finicky for me earlier, I would hit print screen before as soon as calculate to catch the numbers

Cody wrote:

I actually just realized you said 7-8k ft/lbs
7000 joules is a little 5000 ft lbf so 7-8k ft lbf would be rather impressive

That's the calculator I use, I do enough math and number crunching already, I use calculators and converters whenever possible

Well I figure constructing the robot just strong enough to take only a single blow from your weapon probably isn't the greatest strategy.

Remember Newton's laws! beef up that mounting bracket and weapon shaft!

i used rotational the torque equation

I do all the math then realize my weapon motor would never see that rpm under load so i just build and hope

Me too haha
I just put as much weight into my drum an the biggest motor I could behind it haha

I have found that with castle esc's that have data logging that if i can keep the start up current A few amps under rated current it will keep the electronics happy