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rcbarend

I'm after a gauge that can hold groundspeed whilst airborne?

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Hi all,I'm after a gauge that can sustain a selected Ground Speed whilst in the air. Something very similar to how the Taxispeed gauge works that has been designed, (which does over-ride the auto-throttle,(if activated) & zeros the throttle when dissengaged.) except of course it makes a test that the plane in on the ground for it to work & has a limit of 40kts,)I need a gauge that works in the same way, except doesn't care that the plane is on the ground, (no ground test) & can be set into the 1000's of kts .... Before people start saying, "You don't want to do that!! - It's not realistic & could make a plane overspeed with relation to the wind, etc bla bla bla." - I don't care about this, what i'm working on is something completely exotic & unrealistic. But a gauge that can hold a ground speed, would be most desireable.I'm certainly not a programmer either & not interested in learning C++ & XML, just for the sake of a gauge. So anyone replying "make it yourself", is wasting their time typing such a pointless statement.However I look forward to positive & constructive answers that can solve my requirement.RegardsAl

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>Hi all,>I'm after a gauge that can sustain a selected Ground Speed>whilst in the air. One could use 'ground speed' rather than IAS or Mach to control the throttle. Some day I may try to program an autothrottle that holds TAS, rather than IAS or Mach.>I need a gauge that works in the same way, except doesn't care>that the plane is on the ground, (no ground test) & can be set>into the 1000's of kts .... I need a lot of things I don't have. Usually it means I have to do it myself if I want results. ;)>I'm certainly not a programmer either & not interested in>learning C++ & XML, just for the sake of a gauge. ....>However I look forward to positive & constructive answers that>can solve my requirement.>Al If I ever get some speed hold working in an XML gauge it would probably be easy to make it hold GS. What one really wants to control Taxi Speed but rarely in the air.Ron

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?????ak .. All Autothrottle does is maintain a specific Airspeed or Mach.I want to be able to control my speed over the ground whilst in the air.

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Thanks for the reply Ron,I wonder if the guy who created the Taxispeed & pushback XML Gauges, would be interested in converting his Taxi gauge into one that can hold a groundspeed whilst Airborne?I've looked at the XML code for this gauge & because i don't know C++ or whatever it's written in, it just seems like nonsence to me.However i can spot that it does test for being on the ground, Which would mean that in theory you could remove this, & increase the speed ranges that it operates by.... in my case to 1000's of kts, so that it will work whilst in the air. Al

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Hi Al,Well, why don't you ask me then ? :-) :-)Just send me an Email (see address in the Taxispeed archive).Whether I'd do it or not depends a bit on where you want to use it for:- Will it be part some freeware thing you're going to publish ?- How complex it should be ....E.g. a SpeedHold gauge (holding the current GS when activating the gauge) is much easier to make than holding a user-preset GS (counters/dial implementation, bitmap etc).And to make a simple control algoritme you have to know how the aircraft behaves to throttle variations. E.g. my Taxispeed gauge works very well for heavy jets, but gives an erretic throttle behaviour for light prop planes.I've found out that designing a control algoritme that works well for any aircraft under any circumstances is quite complex. Even Microsoft goofed up with their new implementation of autothrottle in FS9.See:http://forums.avsim.net/dcboard.php?az=sho...topic_id=136582Cheers, Rob Barendregt

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>..........>I've found out that designing a control algoritme that works>well for any aircraft under any circumstances is quite>complex. Even Microsoft goofed up with their new>implementation of autothrottle in FS9.>>Cheers, Rob Barendregt I could adjust the SPD hold parameters in REC 1199 of the AIR file in FS2K and get much faster SPD control. In general, you need both Rate and 'Position' (in this case, speed is 'position', acceleration is 'rate') feed back. I'd increase the Position gain, and the Rate Gain FB parameters in REC 1199 to get tight SPD control. Can't go too high with either. The spool up time of the turbine can also have a large effect. And, the mass of the AC relative to thrust. I also set SPD hold for most of my Prop AC and have little trouble with stability (sometimes at low speeds). I need to hold SPD for various flight tests. I already got Vdot (acceleration), in my XML test gauge, also VS and 'VSdot'. However, I broke it and everthing displayed is dead now. Many of the variables in Test Base.XML can be used in autopilots and other things; for now I'm just displaying them. Testing FS2K2 and FS9 AC is time consuming, it takes forever for SPD to stabilize. I often run at 4X to get to the next test speed.Ron

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Rob BarendregtThankyou very much for replying!!!I'll email you as requested, the details of what I'm after.CheersAl

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Hi Ron,The only parameter I could find in a FS9 aircraft.cfg file that influenced the AutoThrottle behaviour is "max_throttle_rate= ".Are there any others ?Unfortunately .air files are not my cup-of-tea yet, but I thought that all .air file parameters where reflected in the aircraft.cfg file (so you could edit them there). Is this correct ?Regards, Rob

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>Hi Ron,>>The only parameter I could find in a FS9 aircraft.cfg file>that influenced the AutoThrottle behaviour is>"max_throttle_rate= ". Right. We found that in REC 1199 also. But, 1199 only works in FS2K and earlier FS versions. I must have changed 'max_throttle_rate' in aircraft.cfg up and down, but it didn't do nearly what I could do with REC 1199 for FS2K and earlier.>Are there any others ?>Unfortunately .air files are not my cup-of-tea yet, but I>thought that all .air file parameters where reflected in the>aircraft.cfg file (so you could edit them there). Is this>correct ?>Regards, Rob Not by any means! Most parameteters are still in the AIR file. And, all the tables. The SPD hold Feedback parameters I mentioned, 'Speed and Speed Rate' would have to be generated in a gauge. Which would control the throttle directly. This should be easier to do than other autopilot functions so perhaps I'll try to do it in XML soon. Setting a Throttle Rate Limit might also help. Further, one would get better performance by making the Feedback parameters vary with AC speed. By finding good values for low speeds, then high speeds, I would know how they should change. Ron

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Hi Ron,Thanks for the explanation. I learned something again :-)".....'Speed and Speed Rate' would have to be generated in a gauge. Which would control the throttle directly. This should be easier to do than other autopilot functions so perhaps I'll try to do it in XML soon ....."I'm working on something simular now in XML for Alistairs'request on a GroundSpeedHold gauge. And I've found out that making a Throttle control algoritm that works under all circumstances (high/low airspeed, high/low changes in windspeed/direction , etc) is a hell of a job :-)Cheers, Rob

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