This is cool, Joe. Thanks for the information.
>> There are now some relatively cheap laser rangefinders with 100m capability and USB output. See eBay 300705075740 I had no idea those things had gotten so cheap ! I don't know how helpful a laser rangefinder would be in battles, but it would be extremely cool ! As we all know, there's no better reason that that to build it. :) - Doug From: rctankcombat@googlegroups.com [mailto:rctankcombat@googlegroups.com] On Behalf Of Joe Sommer Sent: Sunday, March 10, 2013 5:33 PM To: rctankcombat@googlegroups.com Subject: [TANKS] paintball ballistics for fire control with laser rangefinders I recently ran some simulations of paintball ballistics to assess the difficulty of using a laser rangefinder for fire control in our tanks. Specifically, I wanted to check sensing/control precision for gun elevation mechanisms. 1) There are now some relatively cheap laser rangefinders with 100m capability and USB output. See eBay 300705075740 for $156, Previously laser rangefinders for $100 were available for hunting, golf and construction but units with electronic output were over $600. I have no idea about accuracy or visibility of the laser spot for these rangefinders. Hopefully they also have an internal inclinometer. 2) You would need to build a gimbal for the laser rangefinder with a coaxial video spotting scope that is independent of the turret (because hulls are never level) and because you must elevate the gun higher than the laser beam due to ballistic drop of paintballs. 3) I attached a graph of gun elevation in degrees needed to hit a target at ranges from 10 to 150 feet. The stars on the graph show elevation angle to hit the target in the center. The squares show elevation angle to hit six inches above the target spot and the circles show elevation angle to hit six inches below the target. These simulations include air drag on the paintball. The green line is a simplistic model for a projectile with no air drag. For range up to 50 feet, you have about 1.1 degree error margin to hit a 12 inch tall target and air drag is not very important. At 50 feet, paintball velocity has dropped to 200 fps from muzzle velocity of 280 fps. Beyond 50 feet, air drag must be considered. At range of 100 feet you only have about 0.5 degree error margin to hit a 12 inch tall target, paintball velocity has dropped to 144 fps and the zero drag model will shoot about a foot too low. 4) Inclinometer or accelerometer chips can measure gun elevation angle with digital precision of 0.035 degrees which should be sufficient. However gun elevation control must be capable of at least 0.25 degree mechanical precision to hit a 12 inch tall target at range of 100 feet. Joe -- -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to rctankcombat@googlegroups.com <mailto:rctankcombat@googlegroups.com> To unsubscribe, send email to rctankcombat+unsubscr...@googlegroups.com <mailto:rctankcombat+unsubscr...@googlegroups.com> Visit the group at http://groups.google.com/group/rctankcombat --- You received this message because you are subscribed to the Google Groups "R/C Tank Combat" group. To unsubscribe from this group and stop receiving emails from it, send an email to rctankcombat+unsubscr...@googlegroups.com <mailto:rctankcombat+unsubscr...@googlegroups.com> . For more options, visit https://groups.google.com/groups/opt_out. -- -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to rctankcombat@googlegroups.com To unsubscribe, send email to rctankcombat+unsubscr...@googlegroups.com Visit the group at http://groups.google.com/group/rctankcombat --- You received this message because you are subscribed to the Google Groups "R/C Tank Combat" group. To unsubscribe from this group and stop receiving emails from it, send an email to rctankcombat+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
