Mailing List flyrotary@lancaironline.net Message #21874
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: How long can you fly on your battery??
Date: Sun, 15 May 2005 09:34:07 -0500
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
You will have to fit a car battery. Too many pumps. With Tracy's fuel pump( one for each tank) no transfer pump no EWP the usual radios Michrotech emc and engine monitoring. Measured in line with a digital meter < 4 amps. 16 Ah batt. = endurance of 3 to 4 hours. The alternater was only 12 amps! 
 
Are you sure you're not using metric amps :-)   I have two of Tracy's pumps, and they pull 6 amps each.  I just don't see any possible way you're pulling less than for amps total. 
 
Are you sure you were on a wire that had full current?  As I mentioned in my notes, I had to turn off the alternator when using the battery cable wire, otherwise, I was measuring the current being put back into the battery from the alternator, and not the current draw from the engine systems. 
 
 Why would the current increase so much with RPM ?  May be a bit more for the injectors.( Full on 2 inj. 14ohms 2 amps) The high pressure pump runs at constant speed.   
 
Injectors and ignition coils would both require more current as the rpm increases.  I'd really like to get some better data on that, since I only have the two readings at 1500 and 3000.  From those two readings, I'm assuming that each 1500 rpm adds another 2 amps, but that could very well be wrong.  One of these days, I need to pull the panel off the right armrest, so I can access the battery cable while seated in the plane, then I can run up to whatever rpm I want to check. 
 
Cheers,
Rusty (waiting for thunderstorms to clear out)
 
Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster