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Field test report for the Monkworkz MZ-30 2.0lb vacuum pad mounted generator


Well-Known Member
Feb 28, 2018
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Bill Judge posted in a thread,
Monkworkz 2.5 lb, 30 amp Lycoming Vacuum Pad Generator
a couple months ago info about his generator. He asked if anyone in the aerobatic community would be willing to field test it. I contacted Bill and he sent me one to install on my Skybolt. The installation was very straight forward. I had to purchase a BandC vacuum pad adapter in order to pick up my oil supply for inverted flight. I also had to find a gear, as my vacuum pad was capped off with a plate and a weld boss to accommodate an AN fitting for my inverted oil supply. Luckily I had the long vacuum pad studs still installed. I had to move my oil pressure pick up to another port since my existing one interfered with the BandC adapter. Bill recommends that you locate the voltage regulator within the length of the generators supplied wiring, which is about 15”. I was able to find a place to mount it, but not on the firewall. Since I’m running an angle valve IO-360 on my Skybolt, my engine mount is too long to mount the regulator on the firewall. You Pitts, or 6cyl folks shouldn’t have a problem mounting it on the firewall. Bill‘s installation manual is very straight forward and he was very helpful on the phone for the couple of questions I had.

Flight testing went very well. It worked as advertised, and supplied all the require power I need for my electrical system. For those of you running a Dynon, MGL, or Garmin display, this little unit will supply plenty of output. At 900 rpm it puts out 15 amps and at 2300rpm 30 amps. I’m running an EarthX 680 battery, the generator began charging it as soon as it came on line. There’s about a three second delay while the voltage regulator goes through a self test before connecting the generator to the bus. The most exciting thing about this generator is it’s size and weight. It weighs 2.01lbs according to my scale, the regulator brings the total weight up to 2.52lbs. I weighed the Plane Power lightweight belt driven altenator and all the mounting hardware for it, that I removed off the front of my engine. It weighed 8.56lbs along with the Plane Power voltage regulator. A substantial 6lbs savings off the front of the aircraft. The unit does require cooling. I added a 3/4” hole in my baffling to accommodate the supplied plastic ducting to the generator. Also, the voltage regulator requires cooling. In my case I welded up a “Y” fitting to branch off my 1” scat duct that supplies cooling air to the firewall mounted EarthX battery. The Y allowed me to run the 3/4” plastic duct to my regulator. All in all it was a simple install and operates just like the alternator it replaced. For those that want a good reliable power supply that is truly light weight, this is your solution. I’m running it as my primary power supply, as could just about everyone in the aerobatic community. So far this has proven to be a great innovation for power. Check out the thread Bill posted to read more of the details about his generator. I apologize up front for my lack of photo skills, but here are a few pics.


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