New “Zenvair-750”, Jeff Cochran, 2,850cc engine, N750ZV


Jeff Cochran of Alabama has been flying his Zenith 750 on Corvair power for the last few weeks. Below is a quick look at the plane and Jeff  with his running 2850cc Corvair at CC#19. I spoke with him recently and he is planning on flying the plane to Corvair College #24 if he can get the test time flown off.

Pink Ticket

Above, Jeff on the left on the day he passed his airworthyness inspection. The plane displays outstanding finish and appearance. In working with Jeff I can attest to his methodical and professional approach to aircraft construction. He asked very specific questions that reveal a lot of thought and reasearch.

 Jeff  supervises the run-in of his 2850cc Corvair at Corvair College #19. Jeff chose to have us build the engine for him. We delivered it at the College #19. The engine features a bearing, the 2850 cc dished pistons, all of our Gold Systems, and Falcon heads equipped with Inconel valves and exhaust rotators. This is a seriously robust engine. The Zenith 750 is a large airplane capable of climbing at very low airspeeds. This combination makes it brutally unforgiving on engines with inadequate cooling or light duty construction. The Corvair’s outstanding cooling and high quality components make it impervious to installations that are the undoing of lighter engines.

Although we assembled the engine for him, Jeff has invested the time to attend Colleges #16, #17,#19, and #21. Because of this, he knows his engine far better than builders who opt for a ‘Buy-it-in-a-box’ imported engine. I wouldn’t characterize Jeff’s Corvair college experiences as purely educational, if you look at the photos from these colleges there was a lot of fun mixed in with it. Jeff’s path to success high lights the Corvair’s flexibility to adapt to the needs, budgets and time lines of individual builders. With other engines, builders have to accept the power plant the way that it is offered, and pay for it all at once. No such condition exists in the Corvair movement. You can tailor it to fit your individual goals.

Thinking of getting started? Haven’t made enough progress this year? The most common thread in the stories of successful Corvair builders is attending a College. We are 33 days from the last College of 2012. Make your plans now, decide to head for Corvair College #24.

Hats off to Jeff Cochran on the completion and first flights of his Zenith 750.-ww

Internet “experts” on Yahoo, the value of advice…..


Just after I finished the story on spark plugs, there was a loud knock on our back door. This is very unusual at night at our place.  It was our next door neighbor Alan. He was short of breath, had a flash light and said only “Come with me.”

It is overcast and pitch dark out here in the country. It rained 5″ in 40 minutes here yesterday, and the whole area is flooded except for the roads.  I was a little reluctant to follow him, as he had seen a 4 foot water moccasin slither into our pond 3 days ago, and I first thought that Alan had seen him again, in which case I was much more interested in having a Mossberg product than a Maglite product.

Turns out, it was a cause for wonder, not alarm. We walked out to the drainage ditch, and Alan showed me 3 large Beavers, swimming back and forth like motorboats. I was stunned. I had never seen one in Florida, and textbooks on wildlife written years ago said that Florida and Hawaii were the only states without them. Yet, right in front of our eyes, 12 feet away, they swam back and forth, and didn’t care about the flashlight nor us.

After 15 minutes, we thought is best to leave them alone. Back inside, I typed “Beavers in Florida” into Google to see what was there. The very first thing that comes up is the same thing that often does, the “Yahoo answers”, where experts write in the answers, and other Yahoo readers vote to confirm which answer is the correct one,  Majority confirming the obviously correct answer……

The most popular, and thus correct answer, was provided by an alleged human named “Sisyphus.” This person holds the coveted “Top Contributor” status with Yahoo, and lists Zoology as his subject. This name wrote in to say “NO, NOT a Tropical animal.” 75% of Yahoo readers confirmed this as the correct answer, “Sisyphus” evidently answers lots of topics with such expertise, as 14,000 people voted his answers on topics as the correct ones. What a beautifully simple display of group networking, and people pooling intelligence! I was momentarily tempted to write Al Gore thanking him for inventing the Internet until I remembered that I had just seen 3 Beavers, they were not dressed as tourists, and we are 75 miles inside of Florida.

On “Yahoo answers”, one person wrote in to say that there are beavers in florida. They offered a brief from the Florida State wildlife site, and gave footnotes on reports. He stated that there were beavers in Florida. Exactly ONE Yahoo reader agreed with this. It was the “wrong” answer in the world according to Yahoo. Below, is the paragraphs from the Florida State site. This answer is further down Google than the Yahoo answer, and required reading more than 5 words for an answer.

“Today the beaver thrives along many of the perennial streams and rivers that course through the landscape of the Florida panhandle and upper peninsula. As architects of wetlands, beavers provide habitat for nesting wood ducks, migratory waterfowl, otters, turtles and fishes.”

“In northern Florida beaver dams may block drainage systems and flood roads, crops, and timberland. Hungry beavers occasionally chew down ornamental trees and venture into fields to feed on crops like sorghum and corn. Wire or hardware cloth fencing at least 3.5ft (1.2 m) high may prevent damage of valuable trees. Daily destruction of dams and removal of dam building materials sometimes will cause a beaver colony to abandon an area. The insertion of water control structures into existing beaver dams can be effective at preventing excessive flooding. Problems beavers may be trapped and relocated but permits from the FWC are required from the regional office. “

How does this relate to airplane building? You can not imagine how many times in the last ten years I have seen homebuilders take advice on building planes and engines from the internet using essentially the same system, ie, ask a big group of nameless people, and assume that the popular answer must be the one to bet your life on. On every facet of aircraft building, I have seen countless builders assume that the answer they read, even when they have never met, nor heard of the “expert”, is correct. Over many years it was my position that aviation internet groups should have limits or qualifications on “advice” that people without experience offer. Counter to my position were hordes of people who claimed that this was the same thing as Stalin style censorship. They all said they if they asked a question, they wanted to hear every answer, and then they would decide what the correct anser was from the options presented.

Obviously, that is nearly the exact equivalent of Yahoo answers, only in this case, going with the wrong answer has some real consequences. I always tried to point out that if you were qualified to sort out the real answer from all the made up ones, then obviously you wouldn’t have needed to ask the question in the first place………I have seen no shortage of people offering incorrect answers to aviation questions. Be careful from who you ask answers, you have a lot at stake.-WW

Spark Plug Issue resolved…..


Earlier this week we had a number of posts on the issue of spark plugs, centered on a hard miss under full power experienced by Guy “A.” I had another two calls with him after he changed to AC R44F plugs that were gapped to .035″. He now reports that the issue appears to be resolved, and he could not get the aircraft to act up as it had before.

In this case, it is worth noting that Guy “A” had previously flown his plane with NGK plugs with out issue. Was the issue the gap, the dirty condition or?  In my perspective, he likely could have gone back to a new set of NGK’s  correctly gapped and the issue would have likely disappeared. But. you have to ask yourself, by what margin?

I advocate the AC plugs because they are the ones designed for the engine, and GM owned both AC and Corvair. This is my beginning point, but the strongest case I can make is that I have never seen an issue in a Corvair flight engine caused by an AC plug. Because of our central location on the flow of information on Corvairs, I have access to many more case histories than any single builder, in addition to our own testing, and a lot of road miles for comparison. I have good evidence that the AC plugs will work perfectly under a wider range of conditions in a Corvair flight engine than any other plug that builders commonly consider.

If you work outside the engine world, it is often easy to forget some concepts that seem simple on paper, but are often forgotten in a frustrating search for an issue in the hangar. Rule#1 is always Go Back to what you know will work. If you have an issue like a hiccup, and part of your set up is different from the norm, then reset your engine to the norm. In this case, the plugs we are speaking of cost a whopping $9.00 for the whole set. If you have an issue with two variables, or what you suspect are two variables, being able to absolutely eliminate one of the for nine bucks is a diagnosis tool that only a foolish mechanic would not utilize. In the aviation world, you can’t let something like brand loyalty to plugs that worked in your motorcycle color your perspective. Your allegiance has to belong to what works. Experimentation is good, but it always has to be done as the expansion of the envelope from a set up that works perfectly. If what you have doesn’t work flawlessly, then fall back to the known until it does. A number of guys resist this, which would be fine if we were shade tree car guys wrenching on hot rods. But this is flying, and it can be for keeps, and most professionals don’t fool around with biases, brand loyalties nor reasons of ego or saving face.

Many experimentals have a lot of outstanding details. But good aircraft are not made of 99% excellent. They are made of 100% airworthy. The plane having the issue is outstanding, you could easily call it 99% excellent. But with a 1% detail like the incorrect plugs gapped wrong or dirty, it is not 100% airworthy. As builders, it is important to get the basics 100% right. I included the Guy “B” story to illustrate that this spark plug story isn’t a Corvair story at all. A nearly identical mistake in reverse on a certified aircraft produced the same result, a plane, that until the detail is corrected, is not airworthy. Both pilots made a simple mistake and missed a basic element. One of the things I would like to point out is that Guys “A” and “B” have more than 10,000 flight hours between them. Would a beginner have made the same mistake? Could have, but I have been training people to build engines a long time, and in my experience, new guys are very detail oriented because they take nothing for granted. If you think about human nature, you can see how guys with a lot of time around different kinds of planes may get complacent about details. If your new to planes and engines, don’t let this story spook you. If you just approach this in the proven format and not add creative touches like other brands of plugs, you will not have this kind of issue. Arm chair commentators will find that last sentence boring or manipulative. For those of us who will fly something other than a key board or an arm-chair, I point out that reliability is supposed to be more boring than unnecessary risk, and yes, I am trying to convince people to at least start with proven set ups.

One of the people I keep counsel with on Corvair experience is Dan Weseman. I was speaking with him about CC#24 plans when this issue came up. He commented to me that he had never had a single issue, even once, with an ACR44F plug, and they have been the only ones he has ever flown in a Corvair. Arguably, no one has flown the Corvair harder than Dan. He pointed out that the AC’s not only work flawlessly, they are also the least expensive plug on the market. He didn’t really see any motivation for working with any other plug.

In an average year, I will get 200 emails asking about things like constant speed props and elaborate injection systems. If you read all of them, it is easy to tell that 95% of these come from people with little experience. If I lined up these 95% and asked them to install a distributor and time it, or to explain to me how you could tell if the engine was on the top of the exhaust stroke of compression by looking at the motion of the rockers,(both things we teach at Colleges,) I am sure these people would be at a loss. Is there anything wrong with their dreaming of injected constant speed planes? Of course not…if the extent of what they came to aviation to do is dream about things. Conversely, if actually achieving things is the goal, dreaming can not take the place of a rock solid foundation of the basics.

None of us were born knowing this stuff. I am glad to teach it to anyone who wishes to learn instead of day dreaming. I can make a very good argument that the builder who creates and masters the operation of a basic aircraft, is a lot safer, and will experience far greater rewards that any builder operating a plane he really doesn’t understand, or is sketchy on the details of a complex aircraft’s function. The guy with the most basic plane has won the game. The guy who consigns himself to daydreaming has not lost the game…..he wasn’t ever playing.  Once the basics are mastered, then moving forward can be done with the understanding that you are not posing or posturing as your own mechanic, you actually have earned the confidence in yourself, the real reward for knowing the subject. -ww