New Zenith 601 XL(B), Conventional Gear, Jerry Baak, S.C.
Friends,
I had a few calls back and forth with Jerry Baak in the past 10 days leading up to his first flight. Every single thing I could think of to ask him had already been taken into consideration. He was very well prepared for his first flight, and when the morning came, it went off without a hitch, because prep work always pays off in aviation.
Above, a good look at Jerry’s 601XL on the first flight. His aircraft has conventional gear just as our 601XL did. The Zenith makes an outstanding tailwheel aircraft for builders who choose to build it in this configuration.
Above, a full, but fairly conventional panel and dual stick controls. Our 601XL was the first XL kit with dual sticks in place of the traditional Zenith Y-stick. The stick geometry on our prototype was good, but the production dual sticks had a slightly revised design that had better control harmony. The military style grips in Jerry’s 601 are appropriate; he has a lot of experience flying F-101 Voodoos in the USAF.
Above, a nice profile of a very good-looking aircraft. Jerry’s plane uses all of our standard installation components.
Jerry’s plane is powered by a 2700cc, 100hp engine. He has been working on it for a number of years, and it is a good example of aviation decision-making. His plane has an MA3-SPA carb of the correct model. His aircraft had Falcon heads from the start. When the Weseman bearing became available, Jerry bought one and installed it. His plane has a Niagara oil cooler. When the Zenith B model wing mods came out, Jerry installed them. Several times a year, I inspect aircraft that have none of these upgrades, but the builder has a $3,000 paint job, a $4,000 Garmin and a $1,500 interior. The choices Jerry made reflect the background of an aviation professional. He adopted all the things that would allow him to take advantage of all of the mechanical upgrades that we had taught builders over the years. You can always paint later.
Jerry’s success brings several thoughts to mind. If you’re wondering if homebuilding is an adventure worth all the effort, let me point out that Jerry has previously flown around the sky in a 1,000 mph fighter and he still finds homebuilding an aviation endeavor well worth the effort. Second, Jerry’s aircraft is another example of the success of our methods of teaching people to build and install Corvairs. I have never seen Jerry’s plane, nor his engine in person. The information transfer on how to build and install the engine was done by Manual, DVDs, a few e-mails, and a handful of calls. For people who are in aviation to find out how much they can learn, what they can master, and what they can build with their own hands, the Corvair has unmatched appeal. Third, after being in aviation for a long time, Jerry understands that Rome wasn’t built in a day, it cost some money to do it, and that it was probably built by persistent people. It is often hard to explain to people just arriving from outside aviation that the people who will be successful have a handful of common characteristics: They are persistent; they like learning; they understand that having a small cast of knowledgeable supporters is very important.
Those new to aviation are often told the myth that they can substitute money for the first two, and they often think that easy answers from local “experts” or anonymous people on the Net are better than factual ones from proven sources. The rest of the world likes answers as fast and conveniently as possible. This works just fine if you’re trying to buy an overpriced mocha cappuccino, if you need to know if Lindsay Lohan is back in rehab, or if you need to know what some D-bag from a PAC just tweeted about his candidate. Having the wrong answer carries little penalty in the above matters. Successful people in aviation all understand that having the correct answer in aviation is always imperative, and quick answers are not a substitute.
If you would like to see a short video clip of Jerry’s plane landing, get a look at this clip:
Above, the machine and its proud creator. Sharp eves will notice that is has a Warp Drive prop, but the decals are from a different company. The plane ran flawlessly, and displayed very good cooling, despite high ambient temps and the engine just beginning its break in. Jerry plans to open up the inlet holes to 4 and 7/8″ and install inlet rings for good measure. This will ensure that the engine stays cool, even at full gross, the slowest climb and full power on the hottest day. Jerry’s plane is the 50th Zenith 601 to fly on Corvair power. It has now been more than eight years since we pioneered the Corvair/Zenith combination with our own aircraft. Zenith builders have a broad variety of possible engines to choose from. The appeal of the Corvair is many fold: It is inexpensive, it is very smooth, very simple, you can build it yourself, it is long proven and well supported, and it is made in America. It isn’t for everyone, but for those who do choose it, it will serve them well.
Hats off to Jerry Baak, the world’s newest Corvair pilot.
-ww
EAA Webinar notes…..
Friends,
EAA headquarters sent me a followup spread sheet with all of the data from last night’s webinar. It included about 120 questions that builders watching wrote in with. When we were doing the session, only the people at headquarters can see the questions, they didn’t come to my computer, so we relied on Charlie Becker picking out 20 questions that time allowed us to answer. Many of the questions were covered in the talk, but I wanted anyone who didn’t get an answer to send me the question directly, I will be glad to answer it for you. The EAA ia good about protecting the privacy of members, and the data we got was not tied to anyones email address, so it isn’t possible for me to answer the questions for people without them resending them directly.
One other note, several people mentioned that the program started 4 minutes late and had some audio difficulties. One or two comments suggested that we should have check the system earlier. Actually Charlie Becker is a stickler about doing just that. He gave us a long tutorial the day before, and insisted we run wire in the house and go out and buy the exact headset model he wanted. We did all these things. At 3pm, Charlie had us do a full dress rehearsal, including every element of the log in, it worked perfectly. We didn’t touch anything. We checked it 25 minutes before broadcast, and suddenly nothing worked in the audio. Grace and Charlie worked to reboot the system several times, and tried everything we could think of without avail. As we got to the last-minute, Charlie quickly hooked up a telephone connection through the EAA switchboard, and then through his office. Instead of everything going through the computer, all of the things I said in the entire interview went through the phone line, where we had little chance to control even rudimentary things like volume. Thanks to Charlie’s quick thinking, the show went on, with little noticeable issue. I asked Charlie if it had ever happened before, and he said that they had not had this issue ever. Hats off to Charlie for saving the day.-ww
Mail sack – 5/10/12
Friends,
Here are some notes that came in the last few days….
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On the EAA webinar, Military and commercial pilot Terry Hand wrote:
William,
I attended the EAA Webinar last night, and wanted to let you know how much I appreciated your time and knowledge. It was well-laid out, informative, and interesting. I am already a believer in the Corvair engine. You just gave me more ammunition for when I talk to other pilots and builders.
Just one question – you spoke about the potential to fly with a high-octane fuel that had ethanol additive in it. Is there a limit to the amount of ethanol, and is it something that is more suited to a low altitude flyer like a Pietenpol as opposed to a higher flying and faster airplane like a Cleanex or a Zenith? Just looking for clarification. Thanks again for a great webinar. Semper Fi, Terry Hand Terry, The engine itself has no issue with ethanol.
However, each builder needs to look at his airframe and make sure that things like his tank material and fuel lines and gascolater gaskets are all ethanol tolerant. Second, builders need to understand that certain carbs lean differently on fuel with ethanol, and there are limits to how much ignition advance you can use with auto fuel. For these reasons, I suggest that builders run the 40 hours of test time on 100ll to establish what ‘normal’ is for their aircraft, and after getting to know this move on to different fuels if they wish. -ww
Builder Harold Bickford wrote:
I rather liked the presentation as the logic behind using a Corvair was well presented. I was surprised that the helicopter engine story came up. Conversely I though the rebuttal was tremendous. Come summer it’s on to Brodhead and Oshkosh and then to actually start an engine project.- Harold
Highlander builder Pat Ray wrote:
Good Morning William Thoroughly enjoyed your EAA webinar last evening. Thank you. I have just purchased a Highlander kit. While at the factory I was pleasantly surprised to discover a Just with a Corvair installed. Anything you can advise me about the possibility of a Corvair powering my Highlander? Thanks a million.Incidentally I retired from AlliedSignal/Honeywell flight department and worked with your cousin Irma Hujer. Everyone loved her.- Pat Ray
Pat, I took the liberty of answering your note on this forum. Thanks for the nice words. You likely saw Scotty’s plane at the factory, everything to this point says it’s an excellent combination. In the coming months I am also working with Dick Holt to get his installation together. Scotty has a number of custom hand-made items on his plane, on Dick’s I am working to see if we can use more of our regular production items like the U-2 exhaust and an Ma3 intake and Gold oil system, so that the installation will be easier for people to replicate at home without the metal working and fabrication stuff that Scotty had access to at the factory. We will have lots of photos as we progress post Oshkosh.
Nice surprise to hear you worked with Irma. Everyone in our family knows her by the life long nick name her father gave her as a child, “Birdie.” Both her father and grandfather were master tool and die makers in the pure Germanic tradition. Her Father Robbie was a major influence on my mechanical world, he lived only 5 miles from us in NJ. He was the best kind of uncle you could imagine. I made a 12″ long brass cannon under his supervision on the metal lathe in his basement when I was 13. Always fun before caution, Robbie showed me how to bore it to .32 caliber and even gave me black powder for it, after swearing me to secrecy. Very exciting when it shot straight through a 4×4″ post in the Masterson’s backyard. Robbie taught me a thousand lessons in the shop, the lasting and most valuable ones being about how to behave in the presence of adults in their shops and that there is tremendous pride in a craftsmans life, a feeling that many people wearing a suit to work long for. He passed away about 10 years ago. Four drawers of my main tool box contain metal working tools from Robbie and his father Max, Starret and Brown and Sharpe stuff, some of it 100 years old. I use it all the time, as both of these men defined themselves by the work they did, and it seems wrong to let their tools be idle. A world without men like Robbie and Max is a lesser place, they left some very big shoes, and I honestly feel my tiny little feet will never do much to fill their empty shoes.-ww
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On Corvair College #23, Corvair aircraft designer Spenser Gould asked:
Hi William, For CC #23 I’m not sure if this has ben addressed before, will there be an ample supply of build tables on site or should builders plan on bringing build tables? Thanks,-Spencer (TGI)
Spenser, we will have tables at the event, although it never hurts to have one of your own. Folding chairs are also good, and people have started to bring shop stools to colleges because some of the detail work is better done sitting down.-ww
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On the topic of economical carbs, Terry Hand asks:
William, This is a very interesting discussion for those of us looking to build a fun, yet economical airplane and engine combination. This is a question rather than a comment. Is this concept of the single barrel automobile carburetor applicable to both the 2700 and the 2850 engines? Also, how would it affect the use of Autogas? I know your strong opinion of using only 100LL during the initial flight testing, but would this work with Premium, ethanol-free Autogas for flying an aircraft after the flight test phase? I look forward to your response. Semper Fi,-Terry Hand.
Terry, The carb we are testing is straight from a nation rebuilder, and is intended to be used with regular auto fuel that contains ethanol. The test runs we have done had ethanol in the fuel, and it showed no signs of bothering the carb. If it did, you could imagine that there would be a lot of people bolting these on Ford cars and going to the gas station that would be ticked off. If the carb runs well on a 3,000cc Corvair we know that it is big enough to run a 2700 or 2850. If it shows itself to be a little on the small side, I can always bump up to the same model carb’s bigger brother that was fitted to Ford’s 200cid sixes. Just once in my life, somewhere out in the middle of nowhere, I want to land on a road near a mom and pop gas station and taxi up to the pumps just like John Belushi in ‘1941’. It would ruin the whole moment if I have to ask the owner if the gas has ethanol in it, thus I am always working to develop data that takes into account that automotive fuel in the US is probably going to always have ethanol in it from here on out.-ww
EAA Corvair Webinar- Wednesday Night, 5/9/12
Friends,
We invite you to visit www.eaa.org/webinar to register for a Hump Day forum on Flying Corvair Planes 7 p.m. Central tomorrow, May 9.
I will narrate a 30-45 minute discussion on Corvair conversions. Charlie Becker of the EAA will moderate 30-45 minutes of live e-mail questions from the audience. We will have a chance to cover some of the new stuff and discuss the upcoming Corvair College #23. The event will be kept for later viewing in the EAA’s archives, but I encourage builders to try to catch it live.
Charlie said already a large number of people signed up for the Webcast. One of the things that I like about a good turnout for events like this and for the forums I give every year at Oshkosh is that it gives the people at headquarters direct evidence that there are still many, many people in the EAA who are interested in craftsmanship, learning and affordable projects. The people at headquarters are pretty smart, and over the years they have adjusted the content and focus of EAA publications to reflect the interests of the membership. Our association has had some large changes in leadership in the past year, and I am sure that the new people will take some time to better understand the many different expectations of the EAA membership. For my small part, I am always looking for positive ways that we can make sure the leadership has a clearer picture of the interests of the traditional homebuilding element of the association. Participating in this Web forum is a good opportunity to accomplish this while getting more information out to builders who have selected the Corvair as the engine that best fits their goals.
If you are on other groups that may have potential Corvair builders on them, we would greatly appreciate you sending out a short message so other builders have a chance to catch this event. We hope to have you there. Thank you-William
Corvair College #23 schedule.
Friends,
A number of builders who are planning on attending CC#23 have asked for a thumbnail sketch of the schedule for the event. Here is the basic format:
Friday, June 8th,
11am; Check in begins, this goes on all day, and some people will arrive later in the event. When you arrive, the first stop should be at the desk to get your credentials and so that we know who is on hand.
12 noon; Work starts. Because a great number of people travel to the college on Friday, we have a gradual start between noon and dinner. I use this time to get a first had look at each builders project and get them launched. I get a rough idea of the order that the engines will be going on the test stand.
2pm: After things are started, we begin engine runs. We almost always start each college with an engine already on the stand. We get a crew of 3-5 people who are not working on their own engine at the college to be the ‘run crew.’ This is usually headed by a guy who has already run his engine at a previous college, (Dan Glaze, your nominated), This crew will do the bulk of the work removing and installing the engines on the run stand. An engine takes about 15 minutes to install, and 25 minutes to remove (work is slower when the parts are hot). Many more people and the builder of each engine are going to jump in on later tests, but I start with a nucleus group that gets a review on the nuts and bolts and safety procedures.
2pm to 6pm; While builders are getting started, we will prep and run any engines that arrive at the college assembled. In small groups I will show builders the pre- run inspection, pre oiling, valve adjustment, distributor installation and static timing.
6pm to 7pm; This is a “hard stop.” At this point, we will take a break for dinner. We usually have several dozen pizzas brought in. During a hard stop I need everyone to put don all the tools and take a break. At this point we will have opening remarks and introductions, and some tactical notes. Having everyone stop is important because I need to make sure that everyone hears the plans and safety brief.
7pm to 9:00; Back to work. Note; the running of engines stops at sunset. If you like to drink beer, I politely ask that you hold off until after sunset, as it’s a bad mix with running engines. The airport we are using is a city owned facility, and the manager is going out of his way to help us. Out of respect this means that we make his life easier by drinking beer out of cups and removing all the empties. (It goes without saying that anyone sipping a beer is going to be taking a break from any of the engine run action.)
9:30 pm Host and tech crew stops. Builders will be welcome to work as late as they like. The host and tech crew stops at this point. If we have a builders component that needs a weld, a special repair or a test or on the spot machining in order for his project to advance, we head back to our personal hangars to accomplish this. We also have our own day one debrief and make minor adjustments for day 2. I always plan on getting this wrapped up by midnight, but it often takes until the wee hours of the morning, which is why it is important that we actually switch gears at 9pm.
Saturday June 9th
8am, Get started. Breakfast will be on hand, and builders are welcome to start before this, but we will not run anything before this.
12 noon ‘Hard stop’ Group photo and lunch, introduction of pilots and more notes;
1:00 back to work. Through out the afternoon, a will be breaking of builders in groups of 4-5 people and giving them hands on instruction in individual aspects of the engines prep. Mark from Falcon will be on hand doing the same thing. Dan Weseman will be giving several demonstrations of how his bearing is installed. If there is a specific thing you would like to see, let me know when you check in. Most of these tasks will happen many times at the event, so you will have numerous chances to see it done and participate. During the event, Grace will be on hand to get everyone parts organized and Rachel Weseman will be overall event coordinator. We are all there to help you get the most out of the event. This begins with every builder showing up with a positive attitude. In 22 colleges, I have had nearly 200 engines run. The people who got it done all came with some prep work and a positive attitude. Working at home alone in a sequential manner is drinking little 8oz. bottles of water. The college is like drinking from a firehose. It is far more messy, and it requires some attitude adjustment, but in the end the rate of transfer is much better and builders realize that the small adjustment is well worth the progress.
6pm to 730 Hard stop for Dinner. Main meal of the event. We want to have everyone take the time to recognize the people who have flown in and people who have come to the college solely to volunteer.
7:30 back to work. On saturday night, work proceeds at a slower pace, as 50% of the people on hand use these hours as social time. We do not run engines after 6pm on saturday to keep the noise down. The tech crew will be on hand until 9pm, but builders are invited to work as late as they like.
Sunday, June 10
Work starts at 8am. Again, builders can start before, but we don’t run engines before this. Breakfast will be on hand. work will continue steadily. Traditionally, things wind down after 12 noon because most people are heading back home after a few hours in the morning. Although we begin cleaning up at noon, the tech crew will be on hand to help anyone finish up an engine that is close to running. We generally aim to get things wrapped up by 4pm. In the past we have worked long into Sunday night, but I am making a real effort to discourage our friends from starting a 6,8, or 10 hour drive home at 10pm on Sunday. We pack enough stuff into the 50 hours of the college that even stong coffee won’t keep you awake for long on Sunday night.-ww
3,000cc Case Modifications.
Friends,
Of the three popular Corvair displacement that we promote, the 2700, 2850 and 3,000cc engines, only the last one requires any modification to the Corvairs case. To build a 3,000cc engine, both the heads and the case need to be machined where the new 3,000cc cylinders are bolted on. Again the 2700 and 2850 require no modifications to the heads or case.
Several years ago, Dan, Mark Petz, Roy and myself, got together and came up with an exact set of specifications for the 3,000cc machining, to ensure that any builder could be assured that parts sourced from any of us would be compatible. Previously there had been a number of suppliers for 3,100cc parts, and each of them had their own way of machining, and builders were often stuck with one of a kind engines, or even engines that had to have individually machined cylinders for each hole. When developing the 3,000cc engine the four of us were determined to eliminate this issue.
The single biggest factor aiding the standardization of the 3,000 over the 3,100 is the fact that the design and geometry of the 3,000 is all Corvair, compared to the 3,100 which has the piston pin and compression height of a VW engine. These compromises make the 3,100 require modified rods and custom length pushrods. The 3,000cc engine, by our design, uses stock Corvair rods and standard length pushrods.
There are a number of other advantages to the 3,000 over previous large displacement engines, but I would like to steer back to just the machine work required for this discussion. (A 3,100 engine also required the heads and case to be machined to fit the larger cylinders.) The primary reason why we went to 92mm as the 3,000cc bore over the 3,100s 94mm bore is to improve the head gasket area and decrease the oversize required when machining the case. A 3,000cc engine’s case has the 2mm difference in case bore, this may not sound like a lot, the it is a great improvement if you need to put a helicoil or timesert in the case for a head stud. On the top, the 3,000cc’s head gasket does not break out into the head stud holes as the 3,100 does.
The above photo is from our website in 2008. It shows a highly modified 140hp cylinder head that flew 200+ hours on our 601. The head gasket area extending to the head bolt holes shows it to be a 3,100cc head. (look at the bolt hole all the way on the right side of the photo.) It has flanged VW exhaust, a modification that I no longer think is a good idea on any flight engine. This head has since flown 400 more hours on Dr. Andy Elliott’s high performance 601 XL taildragger. A strong word of CAUTION: No one should consider using stock 140 heads on any flight engine. They are notorious valve seat-droppers, and will actually produce less horsepower on typical 2,700cc engines. Flow-wise, they only make sense on high rpm 3,000’s and 3,100s. The 3,000cc engine we are building for our own aircraft has a set of Falcon heads from a 95hp Corvair. Over the years we have tested countless ideas and concepts. Some, like the heads above have limited application in the hands of the right pilot. The amount of time I spend working directly with builders gives me a very good take on what they are personally looking for in an engine. Our testing allows us to suggest which Corvair will provide what they seek.
If you are heading to College #23, and you are thinking of building a 3,000cc engine, you need to send your case in for machining to Dan very shortly. Several cases have already arrived, and Dan is setting up his very accurate tool room mill to machine these cases. The cost of this modification is $150. Dan wanted me to point out that it isn’t practical for builder to bring their cases to the college and have Dan try to machine them the same weekend. If you are planning on a 3,000cc engine, this is the week to scrub the cases, pack them carefully, and send them to Dan. We will have them ready for assembly at the College. (If your building a 3,000, but can’t make the event, you can still send the cases in for the machine work.) Again, this work is completely compatible with the 3,000cc kits sold by Mark Petz at Falcon and the kits sold by Roy.-ww
Mail Sack, 5/7/12, all topics….
Friends,
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 Elliott
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
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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.
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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
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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
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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
MGL vs Corvair ignition issue
Friends,
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.











