---------------------------------------------------------- RV8-List Digest Archive --- Total Messages Posted Sat 06/23/12: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:37 AM - Electrical System Design () 2. 01:36 PM - Re: Electrical System Design (Brian Huffaker) 3. 05:21 PM - Re: Electrical System Design (Carl Froehlich) ________________________________ Message 1 _____________________________________ Time: 10:37:30 AM PST US From: Subject: RV8-List: Electrical System Design How important is it to maintain elevator trim system capability? I am planning to use a VP-X Sport for primary circuit protection, but the =9Cget-down safely in case of alternator failure=9D mode will drop out the VP-X and provide essential power via back-up circuits fed directly from =9Calways hot=9D battery busses. The system is designed for day/night capability. Right now it includes 2 PC625 batteries, paralleled for normal operation, but feeding separate busses which will support the essential load with master switches =9Coff=9D. I will =9Cbelt and suspenders=9D the PFD with a Dynon back-up battery. My only concern is losing elevator trim capability, although there might be others I have not thought of. I am planning to keep the AP servos powered. The system is a bit more complex than I would like, but if it prevents a black cockpit at night it will be worth it. Stan Loer RV8 Very Slow QB ________________________________ Message 2 _____________________________________ Time: 01:36:49 PM PST US From: Brian Huffaker Subject: Re: RV8-List: Electrical System Design On Sat, 23 Jun 2012, stazel@cpros.com wrote: > How important is it to maintain elevator trim system capability? I am [much snippage] If you lose elevator trim, pilot workload goes up, but as long as you are paying attention, it shouldn't be that unsafe. You wouldn't be able to let go of the stick at any but the trimmed speed, if you were trimmed for cruise when you lost power (as would most likely be the case) stick forces on landing would be a bit heavy. I'll leave how heavy to those with flying RVs. Fatigue could become a factor if you had to fly a long way out of trim. A trim runaway is the more dangerous condition Brian Huffaker, DSWL (bifft@xmission.com) RV-8A 80091 wiring electrical 1/4 Starduster II N23UT down for engine overhaul ________________________________ Message 3 _____________________________________ Time: 05:21:03 PM PST US From: "Carl Froehlich" Subject: RE: RV8-List: Electrical System Design Weird. Two PC625 batteries provide ample power for full IFR flight to fuel exhaustion (large loads such as landing lights, strobes, pitot heat excluded). Why would this system design in loss of trim for an alternator failure? The trim servo is perhaps a 100ma or so =93 nothing. Carl RV-8A (800 hrs) RV-10 (13.5 hrs) From: owner-rv8-list-server@matronics.com [mailto:owner-rv8-list-server@matronics.com] On Behalf Of stazel@cpros.com Sent: Saturday, June 23, 2012 1:37 PM Subject: RV8-List: Electrical System Design How important is it to maintain elevator trim system capability? I am planning to use a VP-X Sport for primary circuit protection, but the =9Cget-down safely in case of alternator failure=9D mode will drop out the VP-X and provide essential power via back-up circuits fed directly from =9Calways hot=9D battery busses. The system is designed for day/night capability. Right now it includes 2 PC625 batteries, paralleled for normal operation, but feeding separate busses which will support the essential load with master switches =9Coff=9D. I will =9Cbelt and suspenders=9D the PFD with a Dynon back-up battery. My only concern is losing elevator trim capability, although there might be others I have not thought of. I am planning to keep the AP servos powered. The system is a bit more complex than I would like, but if it prevents a black cockpit at night it will be worth it. Stan Loer RV8 Very Slow QB ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv8-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV8-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/rv8-list Browse Digests http://www.matronics.com/digest/rv8-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.