---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 02/16/21: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:35 AM - Re: DC Wiring Diagrams for SPA Panther LS (jsajpf) ________________________________ Message 1 _____________________________________ Time: 05:35:07 AM PST US Subject: AeroElectric-List: Re: DC Wiring Diagrams for SPA Panther LS From: "jsajpf" Rick, Does the aircraft pitch trim system include a manual trim wheel or lever, or is the sole means of pitch trim the electric system? The electric trim circuit lacks a combination "arm" and "command" input (think of the split trim switch on many GA type certificated aircraft). Only a "command" input is shown. I think this single input is common in E/AB airplanes but I personally do not favor it. I think your relay circuit for pitch trim (rather than direct switching of motor current with a momentary switch) provides a measure of protection against uncommanded or runaway pitch trim, in that an opposite direction command at the switch will change the state of the motor legs, at least stopping further trim movement while the switch is held. I think a cutout switch to remove power from the motor circuit is advisable, located such that a free hand can get get to it, perhaps while on its way to the manual trim control (mine will be next to the manual trim wheel). Removal of power from the existing circuit would require the pilot to locate and open the trim circuit breaker while also fighting the trim forces, and countering the uncommanded trim in some way (e.g. restrain the manual trim control or holding opposite direction trim command with the switch). Does the trim servo connect to the trim system in a way that allows the servo input to be manually overriden; meaning a slip feature that would allow holding the manual trim input against servo motion? Perhaps the servo itself has this feature? These system safety measures may all be unnecessary on the class of airplane you're building. I advise you to consider what sort of trim induced control forces you might expect at the speeds and configuration combinations of the airplane, and then look to see how quickly the electric system might get you into trouble; rate of trim, range of trim, etc. The airplane I will build is noted for trim sensitivity at cruise speeds so I'll have at least two trim speeds (slow for flaps up, faster for flaps down). There are systems that allow continuously variable speeds as well, typically based on airspeed. I've seen some all-electric trim systems incorporate a direction reversal switch that would allow a measure of control redundancy should a single direction fail. Well done on the wiring diagrams! John Read this topic online here: http://forums.matronics.com/viewtopic.php?p=500724#500724 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.