Frank wrote: > I multiply that figure by 2 to account for dynamic loads.
Depends on the suspension design. In a captured suspension where the bottom stops determine ride height, you can put in as much spring rate as you want for higher dynamic loads. In a floating design (where the suspension can go above and below the desired ride height), stronger springs will reduce the suspension arm throw as the (extension) springs will not stretch as far for a given weight and thus will not offer as much “return” before the spring collapses back to its original length. Basically, given the same length, the higher rate spring will give a shorter suspension range than a lower rate spring. I forgot to mention another issue which hadn't occurred to me earlier. Force multiplication must be factored when determining spring rate in a internal sprung design (such as used in tank T014). Since most internal arms that the springs attach to are shorter than the external suspension arm there is a significant force multiplication from the force pushing up on the roadwheel and the force being applied to the suspension spring. A simple example would be where a tank with 2” long suspension arms and 1” long internal spring arms will require a 24 pound force at the spring lever to counteract a 12 pound force pushing on the roadwheel. Here’s a handy lever force calculator. http://www.engineersedge.com/calculators/levers/page_levers_1.htm If using this calculator, the X variable will be the length of the external arm (between the wheel axle and pivot point), L the length of the spring arm (pivot point to spring attachment point), and F the force pushing up on the roadwheel (tank weight divided by the number of roadwheels). Steve Tyng -- You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to [email protected] To unsubscribe, send email to [email protected] Visit the group at http://groups.google.com/group/rctankcombat
