Wouldn't it just be easier to vary the speeds of the tracks on the first module of the vehicle? Just speculating... or is the whole conversation about how to make it skid steer?
On Sat, Nov 28, 2009 at 7:56 AM, callum.king.underw...@googlemail.com < callum.king.underw...@googlemail.com> wrote: > I do find myself agreeing with you but it would be damned cool to see > it done. One of my friends is considering making an RC car, Hasnt > decided on size but if it was built 1/6 it would be allowed seeming as > it is a military vehicle. Vehicle in question is a jackal. If it was > built as the mk19 version would it be allowed a paintball gun? mk19 > could perhaps counts as a 40mm as that is what it fires. > > On Nov 28, 4:44 pm, Frank Pittelli <frank.pitte...@gmail.com> wrote: > > callum.king.underw...@googlemail.com wrote: > > > A linear actuator may have enough torque to turn 2 halves. Or a > > > combination of multiple actuators??? > > > > Sorry to burst any bubbles ... but I don't think the Warthog would ever > > be an effective support vehicle in the hobby ... despite it's novel > appeal. > > > > Specifically, common skid-steering (forward on one track and reverse on > > the other) will *NOT* work because as soon as you reverse one of the > > tracks on the tractor or trailer, the pivot joint will lock over in one > > direction and the vehicle will prevent itself from completing the turn. > > That's how we originally tried to steer the Goer and it was an > > immediate failure. Even though it used wheels instead of tracks and the > > trailer wheels were free-wheeling, the lateral friction of the wheels > > was enough to stop it dead in a turn. > > > > The Goer and ZD3000 both use a modified skid-steer control (called > > tractor steering) that simply cuts off power to the inside tractor wheel > > when turning, allowing the inside wheel to free-wheel during the turn. > > That allows the single outer wheel to turn the tractor and the > > free-wheeling trailer follows it around the turn. > > > > Unfortunately, I don't think such a modified skid-steer control will > > work at all for the Warthog. Since a track has far greater rolling > > resistance than a wheel, a single track on the tractor will not be able > > to turn the tractor by itself, let alone with a tracked trailer behind > > it. We've proven this many times on the battlefield when a tank track > > stops working for some reason. In those cases, the tank continues to > > move along with only a slight curve to it's direction. Basically, the > > free-wheeling track acts like an outrigger, helping to keep the tank > > going straight. > > > > That eliminates both forms of skid-steering commonly used, so what's > > left? The only approach I can think of that has any chance of working > > is to use the same approach that the real vehicle uses: computer > > controlled operation of all four tracks. Specifically, when you want to > > turn the vehicle, the computer starts varying the relative speed of all > > four tracks to (a) cause the tractor to go in a given direction and (b) > > keep the tractor-trailer angle constant during the turn. This is *not* > > as easy as it sounds, because the trailer has to start and stop turning > > *after* the tractor does (so it will travel along the same path). > > Moreover, the amount of time depends on the actual speeds of the > vehicles. > > > > As a veteran software developer, I wish "good luck" to anyone that > > develops the required software. Even if they do get it working, the > > resulting vehicle will under-perform all other support vehicle designs, > > rendering such clever programming virtually worthless. Specifically, the > > use of relative track speeds to turn the vehicle also means that the > > turning-radius of the vehicle is significantly increased. Tanks have a > > zero turning radius because of full skid steering. The Goer and ZD3000 > > have a slightly larger turning radius using tractor steering. Wheeled > > vehicles using conventional steering have a greater turning radius, > > limited by the angle of the steering wheels. By far, the worst turning > > radius would be the Warthog. > > > > When it comes to a tracked support vehicle, I think that the best (and > > perhaps only) choice is the FV103 Spartan as evidenced by SV015 built by > > Mike Mangus. With a zero turning radius, go-anywhere performance and > > heavy-hauling capacity, I don't see any other vehicle matching it in the > > support vehicle category ... including the venerable Goer and UN Peace > > Keeper. It costs more to build and operate, but over time I think it > > will prove to be the most effective support vehicle design. But, that's > > just a personal observation based on a relatively small amount of design > > and battlefield experience. > > > > Frank "A high-speed Spartan would change the game" Pittelli > > -- > 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 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
