On the topic of MGL, 601 builder and pilot Andy Elliott wrote:
A partial counterpoint – I have been running an MGL Ultra EFIS in my plane since day one. I was, in fact, attracted by the experimental and highly customizable nature of the system. Plus, the MGL remote data acquisition unit (RDAC) minimizes the number of instrumentation wires that have to go through the firewall, especially compared to the Dynon units.
I also knew, as an early adopter to the Corvair platform, that I would have to do some constructive engineering along the way. Note that this is much the same reasoning that led me to choose a Corvair over a Jabiru or a Continental. MGL had zero guidance on how to hook their EFIS to a Corvair (or any other distributor-driven ignition) at the time.
I claim that it absolutely *is* possible to use the ignition grounds as a reliable source for the tach signal. I have been doing that for ~440 hours, and have never had any trouble at all. However, in order to get the system to work with two ignitions, I needed to add couple of diodes to the wiring to prevent them from shorting each other out. Seemed pretty obvious to me, but perhaps not to everyone.
As William says, getting useful advice is not always easy. I get a lot of mine from him! But I would have been happy to send anyone my wiring diagram, along with the caveat that it worked for me and might not for you! I do agree that plastic sensors have little place in reliable fuel systems. I’m happily measuring my fuel flow with a Flowscan transducer. [Flowscans are all metal-ww]
That’s why they call it Experimental aviation! FWIW,
Andy: The setup in Shayne’s plane did not have the same resistors and diodes. While your system obviously works, I still prefer to have builders use a system like Chris Smith’s that is divorced from the ignition. Thanks for the input, all perspectives welcomed. -ww
On the subject of new brackets, Buttercup builder and CC veteran Daniel Kelley asked:
Hi William, will the new bracket work with Roy’s 5th Bearing?
Thanks, Daniel Kelley
Daniel: As long as your starter has a bolted on ear, not a welded one, the bracket will work. It takes a slightly different length spacer, but this isn’t a big deal. Roy makes a tail bracket for builders using his bearing that fits right up against our Gold Front Starter Brackets in a very neat installation.-ww
Corvair College #22 veteran Vic Delgado wrote:
I like it! I saw one at CC#22 on the engine you finished and really liked the simplicity and the functionality of it. Great Job William, no doubt I will be purchasing one too.
On the post about Alan Uhr’s 601-XL(B), 601 builder and pilot Phil Maxson wrote:
Congratulations to Alan! This is a very nice looking plane. If your experience is like mine, it will bring you many hours of pleasure in the future. William’s point about relying on a proven design is right. The way to move from building to flying in the quickest and safest fashion is to rely on a proven configuration. Happy flying!- Phil
On the photo of of the core crank decorations on the CC#23 post, Vic Delgado wrote:
Now That is a fine job of wrapping! Nice going Kendall!! LOL
On the subject of College dates, Rob Stapelton, builder from Alaska wrote to ask:
Will there be other College events later this year? If so where, when?
Rob: The schedule for the year is pretty full with Brodhead and Oshkosh this summer. The next College we have after #23 is going to be Barnwell, S.C., the same location where we had #19 and #21. We hold this College as a year-end event, and it is always on the three-day weekend in early November for Armistice Day. We don’t have the exact info yet, But P.F. Beck and his crew have said they are really looking forward to their third round as hosts.-ww
In the past few weeks we had been going over an ignition issue with 650 builder and pilot Shayne McDaniels. His aircraft refused to run well on the points ignition. He changed the points, went over the system, and even mailed it back to me to have it checked out. Just to be sure, he went over all the other systems on the engine to eliminate the possibility that he was looking at a secondary effect. The plane had been unused on the ground while he was doing some work on it and upgrading things in the panel, and the connection is not immediately apparent that the issue was being directly caused by his MGL disrupting the ignition circuit. Shane is a very experienced builder, and he had received the wiring diagram for the tach hook up from an MGL dealer. This wiring was directly responsable for the erratic ignition. When the connection was removed, the plane instantly ran perfectly. It had been a long goose chase.
Our conversion manual suggests never hooking the tach signal to the ignition. This is for good reason. If you are one of the people choosing to use MGL products, the correct solution is to use a sending unit to count bolts in the flywheel. Dan Weseman as a few sending units for this in his hangar. I am told that MGL even has a sending unit that would perform the same task. Either way, just because a company makes avionics doesn’t mean they understand ignition systems. You might think that they would be very reluctant to suggest a connection that was not tested, but it isn’t the case. I am not singling out MGL. Other companies have also made suggestions for tack signals that proved erroneous. As a builder, the best thing for you to do is choose a system that doesn’t connect to the ignition, (like the Stuart Warner tachs) or only use a system that has been proven over 100s of hours to work with the Corvairs ignition. Grand Rapids, MGL and Dynon are all successfully flying with Corvairs, but none of these are using the tach wiring that the manufacturers first recommended.
The above photo is Shane and Phyllis McDaniels’ 650 at Oshkosh 2011. The fantastic finish work was admired by legions of builders all week. This aircraft was the first amateur built Zenith 650 to be registered with the FAA. When a new model of aircraft comes out and the first one flying is Corvair powered, it speaks a lot about the popularity of the powerplant. This is the aircraft in which the MGL unit was interrupting the ignition.
In our booth at Oshkosh 2011, I stand with three pilots who flew in their Corvair powered Zeniths. From left to right, Shayne McDaniels who flew in a 2,700cc CH 650 from Missouri, Woody Harris in a 2,850cc CH 601B from California, and Andy Elliott in a 3,100cc CH 601B from Arizona. If you add in the time we put on our own 601, you are looking at 1,400 hours of ‘Zenvair’ experience. These aircraft have flown in 40 out of 50 states. We have several dozen other zenith pilots who have written their own chapter in this same story. In the eight years since we pioneered the Corvair/Zenith combination all the development and testing has long been done. Any issue that builders experience today is a case of an aircraft that isn’t of our standard configuration or is having a problem like the MGL tach connection issue.
In the foreground above is Dan Weseman’s Wicked Cleanex. Off his wing, Chris Smith flys the Son Of Cleanex. The photo was taken over a bend in the St. Johns River in North Florida in 2007. Dan’s aircraft used a Grand Rapids system, but Chris’s used an MGL. On the first flight of Chris’s plane, it had a very high oil temp indication, a very serious issue. It made little sense because Chris’s aircraft was a clone of Dan’s, and Dan never had oil temp issues. After investigation the issue was traced to the MGL unit set to read the incorrect value from the VDO sending unit. This type of issue can not happen with a mechanical system. The MGL is a computer person’s idea of a good instrument. It can use many different sensors, but I prefer systems that are fool-proof and use high quality sensors. Chris’s plane did not have the ignition tied to the tach, Chris and Dan made a system to have the tach signal come from a sender counting bolts on the flywheel. To be fair, most people who have studied MGL’s products agree that the things they make today are better thought out than the generation of things in Chris’s aircraft, but builders using them are still advised not to use any connection to the corvairs’s ignition system.