In the choppers, the collective is controlled by the throttle. I am trying to make the chopper hold a specific height, and have it adjust the throttle to do so. I have seen Arne Bartells hover gauge, and was blown away, so I thought I would try to do one in xml.here is what I have so far:(A:Radio height, feet) 10.5 < if{ (A:GENERAL ENG1 THROTTLE LEVERPOSITION,part) 16384 * 50 + (>K:THROTTLE1_SET) } els{ (A:GENERAL ENG1THROTTLE LEVER POSITION,part) 16384 * 50 - (>K:THROTTLE1_SET) } It pops up to 20 or so feet AGL, then decreases throttle and settles back on the ground and off it goes again. Seems it cannot refresh itself fast enough to maintain anything like a close altitude.Any suggestions?Steve

I have no idea to implement it in XML, but the hover gauge uses a PID algorithm to hold a certain vertical speed, which again is proportionally dependent on difference between desired and real altitude. The reason was that I first built a gauge to hold the speeds to all axis constant and afterwards added a rad-alt hold feature, where you have a constant speed to reach an altitude and near the altitude slow down the progress.For the collective you need at least a P and I character. P is "reaction proportional to difference", I is "proportional to the intgral of the difference" (you add up the diffences over the time). The factors for the P and I part have to be chosen (read: tried out) very carefully to avoid a resonating effect where the heli bobs up and down like hell.I experienced the hover gauge as a bit, but not too much complicated and especially the alt hold feature is the trickiest one due the typical helicopter dynamics. Maybe there are easier ways, but I haven't found them yet. In C it looks halfways clear, but in XML it would look quite messy.Arne

ArneThanks for the reply. What amazes me most is I actually understood it !!!I have tried but the best I can do is get the chopper to oscillate up and down 50-100 feet, So I give up.I hope you will consider my request from the e mail I sent you last week in respect to customising the Hover gauge.Thanks a millionSteve