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rcbarend

Trim movement light

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Hi All,For an autotrim system which is coupled with the autopilot I need some trim movement (trim in motion) lights. One light for the movement up and one for trim down. They illuminate only while the elevator trim is in motion(!) and controlled from the AP/FD. I have absolutely no idea of how to realize this. Hope someone has an idea or a sample code.Best RegardsMatthias

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Hi Matthias,There's a few ways of doing this, but the simplest way probably depends on what you have right now.When you say "For an autotrim system which is coupled with the autopilot....", do you mean that you have created your own (XML ?) gauge that determines/sets trim commands based on some criterium ?If so, the simplest way is to embed the lights in that gauge: you know in the gauge (by a state or alike) that you are controlling trim, so you can show the light accordingly.If not (and you let FS control the trim) when the AP-master and AltHold is On, a small display gauge is easier, which sets the light On when the measured position of the elevator trim is different than the previous schedule cycle.If you want help, I'm willing to make it for you.But since I need some more info, please Email me ....rc.barendregt@planet.nlCheers, Rob Barendregt

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Hi,Made a string to measure the trim Pct and let the light come up when values exceed the straight and level situation (11-13)%((A:ELEVATOR TRIM PCT,percent))%!d!"UP" (A:Autopilot master, bool) (A:ELEVATOR TRIM PCT,percent) 14 > &&"DOWM" (A:Autopilot master, bool) (A:ELEVATOR TRIM PCT,percent) 10 < &&Hope it contributes,Jan"Beatus Ille Procul Negotiis"

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Hi Rob and Jan,First of all thank you very much for your response and try to help.Yes, it's a XML gauge (sorry, I forgot to write it here). But this gauge do not use separate custom commands to control the trim. In the real aircraft it's just a function which has to be activated to let the FD/AP control the elevator trim. Or more exactly, you switch on a separate motor for the trim control. Without activating the autotrim the motor is switched off and so no trim function could be forced from the AP. The implementing of this function is very simple, as I'm programming the AP on this way that no vertical change mode (the modes which requires trim changings) is possible without setting the switch to on. This is no problem. But not so for the lights. The lights should just illuminate while the trim is in motion.For example: I climb with a rate of 500 ft./min. with a current and leveled off elevator trim position of 10%. Now I move the AP pitch wheel to increase the climbing rate to 1000 ft./min. For this a trim position of let's say 20% (just an example) is necessary. The "up" light should now go on while the trim wheel is automatically changing from 10% to 20% (caused in the gauge from the AP VS hold mode) but should go out when the trim wheel leveled off at 20%.I hope this helps pointing up my problem.Best RegardsMatthias

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You might store the trim setting at the end of the drawing in a custom L: or G: variable. At the beginning you commpatre it to the previous value. If different you draw the light if also the AP is on.Something like (not tested):(A:Autopilot master, bool).... (A:ELEVATOR TRIM PCT,percent) d (G:Var1) != r (>G:Var1)Not too sure about the d(uplicates) and r(otates), to be honest. If you use L:vars use different L: vars for more than one appearance in the panel, otherwise the old value is overwritten from different gauges.Arne Bartels

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Hi Matthias,Understood.As said, I'm willing to make such a gauge for you (for free of course :-) )If you want that, send me an Email at the address mentioned above.CHeers, Rob

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Hi Arne and Rob,@Arne:Thank you very much for the example code. I think the store and scan function is very useful as, beside this trim light, I have a couple of other uses for it and never know how to realize it.@Rob:Thank you very much! Yes this would indeed be a help for me as there are still a lot of gauges to do for this panel and so I could concentrate on those gauges. I will contact you within the next days when I'm back home.Best RegardsMatthias

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Hi Matthias,Had some spare time :-)See attached zip file and included Readme ....Cheers, Rob

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Hi Rob,Works OK, lot of "flicker" on my flightdeck now (Turbulence)What planes, if possible a picture, use such a gauge, light?Jan"Beatus Ille Procul Negotiis"

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Hi Jan,I would know :-)Matthias should answer that .... He was the one asking for it ...LOLCheers, Rob

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Hi Rob and Jan.@Rob:Wow, thank you very much for this example. Of course I have to make some adaptations with the bitmaps and to add some further conditions regarding the electrical supplyment and AP requirements. But this is no problem. Once again, thank you for your efforts.@Jan:Such a gauge is often used in older turboprops having a separate switch for the trim servo motor (very often together with the Honeywell SPZ-200 or SPZ-500 AP's). Mostly in those models which are originally not designed for an AP or for those models which are supplementary added with an AP. A good example is the BAe Jetstream 31 (the panel I need the gauge for). Unfortunately I could not post a link to an Airliners.net photo as I do not have access to this site from my company. But if you take a look at a Jetstream photo on this site you will see the trim lights in the glareshield (below the annunciators and below the FD switchbar). There are four square lights. The both left lights are for the trim up and down function of the trim motor. But take care. Those lights only exists if the aircraft is equipped with an AP. Not all J31 own AP's so you will find a lot of J31 pictures without those four lights.Best RegardsMatthias

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Hi Matthias,Hope we can admire the results soon :-)Success !Cheers, Rob

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