Thanks Bob! Smooth Sailing, Karlton Spindle http://www.MultiplexRC.com ----- Original Message ----- From: Bob Parks <[EMAIL PROTECTED]> To: Karlton Spindle <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Thursday, July 27, 2000 3:10 PM Subject: Re: Servo temp Drift > > Karlton, > I dont subscribe to the soaring list, so it probably wont let me post. > If not please forward this for me, and send me copies of any relevant > replies. > > Bob > > In our last episode, Karlton Spindle wrote: > > I didnt do a lot of testing, but mainly concentrated on Multiplex Super > FL mc/V2 servos. This is for a NASA flight test as part of the Mars > Airplane effort. We want to get real aero data at the proper Reynolds > and Mach numbers (roughly 40K and .65 cruise respectively). So we will > be flying a 3 meter airplane at 110,000 ft after a balloon drop at > 120,000 ft. (it takes about 8,000 ft to get to flying speed and to pull > out) > > Anyway, the airfoils are very thin for the low RN, so not much will fit > in the wings and tails, and since it hits Mach .75 or so in the pullout, > having a good tight servo is a real good thing. > > I have tested the Super FL in a thermal vacuum chamber through a typical > pressure and temperature profile for sea level to 90K ft, and also done > some very cold testing (-100F) as well as a room temperature endurance > test at 125Kft for a couple of days (servos self heated to about 130F). > > I had to remove all the grease, replacing it with a dry lube (probably > limits the lifetime, but it only needs to work for for a couple hours), > and I also had to rework a plastic output shaft to pot coupler, which got > loose below about -40F, but after that the servos worked fine over the > whole temperature/pressure range and there was NO noticeable temperature > drift. I didnt measure it precisely, but if there was drift it was not > over a degree or two. > > They were a bit sluggish below -70F or so, if they were cold soaked > without moving. However they would self heat enough to behave well after > a few seconds of movement. In all cases the servos were driven by an > AeroScientific servo driver, it is crystal controlled and stayed at room > temperature, so not much drift there! > > The Aerovironment Pathfinder airplane is also using some type of RC > servos, also going down rather cold, but I dont know the details of it. > > So, in summary, I dont know about other servos, but the mc/v2 Super FL > dont drift with temperature! > > One other note.. you have to be pretty careful with the airplane and > linkage design to avoid temperature drift there! For the high altitude > flight, we are using CF pushrods in a CF airframe. > > Since I am not on this mailing list, please send a copy of any replies > directly to me at [EMAIL PROTECTED] > > Thanks > > Bob Parks > > ************************************************************************* > * Bob Parks One of the penalties for refusing * > * [EMAIL PROTECTED] to participate in politics is that you * > * [EMAIL PROTECTED] end up being governed by your inferiors.* > * http://www.kidsource.com/ --Plato * > ************************************************************************* > > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
