| Forces Generated by Spinning Weapons | |
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Chris R
People Skills : 4646 Registration date : 2011-08-30 Age : 28 Location : Pinetop-Lakeside, AZ
| Subject: Forces Generated by Spinning Weapons Thu May 10, 2012 2:48 pm | |
| 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? | |
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Alex P. HASD Bots great contributor
People Skills : 5011 Registration date : 2011-03-30 Location : south west pa
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 3:11 pm | |
| my weapon hit with some where in the neighbor hood of 77.8 lbs, at least according to the physics | |
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Alex P. HASD Bots great contributor
People Skills : 5011 Registration date : 2011-03-30 Location : south west pa
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 3:12 pm | |
| if this helps what so ever | |
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Chris R
People Skills : 4646 Registration date : 2011-08-30 Age : 28 Location : Pinetop-Lakeside, AZ
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 3:24 pm | |
| - 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? | |
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Cody 2000+ club
People Skills : 7812 Registration date : 2009-03-16
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 3:46 pm | |
| 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 | |
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Chris R
People Skills : 4646 Registration date : 2011-08-30 Age : 28 Location : Pinetop-Lakeside, AZ
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 4:00 pm | |
| - 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. | |
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Cody 2000+ club
People Skills : 7812 Registration date : 2009-03-16
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 4:06 pm | |
| 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
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Chris R
People Skills : 4646 Registration date : 2011-08-30 Age : 28 Location : Pinetop-Lakeside, AZ
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 4:09 pm | |
| - 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. | |
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Cody 2000+ club
People Skills : 7812 Registration date : 2009-03-16
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 4:44 pm | |
| 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 | |
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Mr. P
People Skills : 4941 Registration date : 2010-12-18 Age : 40 Location : Pittsburgh
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 6:31 pm | |
| i tend to use this when thinking of new designs. maybe this will help you lhttp://www.teamcosmos.com/ke/ke.shtml | |
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Cody 2000+ club
People Skills : 7812 Registration date : 2009-03-16
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 6:49 pm | |
| 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 | |
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Camden W big contributor
People Skills : 4920 Registration date : 2011-04-10 Age : 29 Location : Blaine Minnesota
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 7:24 pm | |
| That KE calculator doesn't work for me... | |
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Cody 2000+ club
People Skills : 7812 Registration date : 2009-03-16
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 7:57 pm | |
| - 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 | |
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Chris R
People Skills : 4646 Registration date : 2011-08-30 Age : 28 Location : Pinetop-Lakeside, AZ
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 8:39 pm | |
| - 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. | |
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Camden W big contributor
People Skills : 4920 Registration date : 2011-04-10 Age : 29 Location : Blaine Minnesota
| Subject: Re: Forces Generated by Spinning Weapons Thu May 10, 2012 8:41 pm | |
| Remember Newton's laws! beef up that mounting bracket and weapon shaft! | |
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Alex P. HASD Bots great contributor
People Skills : 5011 Registration date : 2011-03-30 Location : south west pa
| Subject: Re: Forces Generated by Spinning Weapons Fri May 11, 2012 3:55 pm | |
| i used rotational the torque equation | |
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Evan Steeves great contributor
People Skills : 5119 Registration date : 2011-02-05 Age : 33 Location : towson md
| Subject: Re: Forces Generated by Spinning Weapons Sun May 13, 2012 2:19 pm | |
| I do all the math then realize my weapon motor would never see that rpm under load so i just build and hope | |
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Cody 2000+ club
People Skills : 7812 Registration date : 2009-03-16
| Subject: Re: Forces Generated by Spinning Weapons Sun May 13, 2012 2:35 pm | |
| Me too haha I just put as much weight into my drum an the biggest motor I could behind it haha | |
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Evan Steeves great contributor
People Skills : 5119 Registration date : 2011-02-05 Age : 33 Location : towson md
| Subject: Re: Forces Generated by Spinning Weapons Sun May 13, 2012 2:43 pm | |
| 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 | |
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