William Wynne

10/24/201310/24/2013

Corvair Oil System, information on oil pressure gauges.

Builders,

A friend of ours who is building a Zenith 750 wrote in with a quick note asking about oil pressure gauges and senders. I pulled together this general set of notes on oil pressure measurement and instruments as a good resource on the general subject. Over the years Corvairs have flown with just about every kind of oil pressure instrumentation imaginable. Going back to my point of Principle vs Preference. On this subject, it mostly falls in the category of preference.

The Builders specific question was focused on sending units for electrical gauges, and their reliability. If I had to pick one brand over another, I will say that I have never had an issue with the senders that are used in Autometer gauges. VDO is usually trouble free, but I have personally had one mess up, and it caused a lot of work with it’s erroneous information. Goes without saying, I wouldn’t use one from the land of Chairman Mao.

Some people are concerned about mechanical gauges bringing oil into the cockpit, but in actual experience, I have never had an issue with it. The line itself is 1/8″ on the outside, but only 1/16″ on the inside, and I generally put a #80 hole in a restrictor, at the engine, so even if the line came off, the flow rate is about 1/2 gallon per hour. For the record, I have never seen even the poorest mechanical line installations leak. You can take the nut off at the gauge with the motor running, and it does not “spray” oil, it just oozes, and even when the engine is hot, the oil really isn’t after six feet of line.

Below is the close up of the mechanical oil pressure gauge I have in the Wagabond. In addition to all the other things I like about mechanical gauges, I like the fact the needle covers a 300 degree arc, allowing you to see very fine changes. The gauge below is $54.97 from summit racing.

Now get a look at the next part, which is an analog electrical gauge. My primary complaint beyond the fact it is electrical is that this type of gauge is only a 90 degree sweep, making small differences had to see. They also cost about twice as much as mechanical after you get the sending unit. It is priced at $69.97, but the sender is about $40. I buy Autometer because of the tiny letters at the bottom of the instrument that say “made in USA”

Auto Meter 5727 - Auto Meter Phantom Analog Gauges

For Builders interested in digital instrumentation, Google the name “Dakota Digital”. Below is one of their instruments, but the come in many different varieties, all made in the USA. They have a website you can buy direct from, it has many choices. Just a reminder, never mention to anyone on the phone while ordering from a non aviation company that you are building a plane. Summit will actually black list you. The people answering the phone have $9/hr. jobs, so don’t jeopardize anyone’s just scraping by living by saying that on the phone, and having them get in hot water for not turning you in. It is an annoying fact of a litigious society, but you are not going to fix it by getting a single mother just above the poverty line fired.

If you would like to read a two part story about the simple panel I built for the Wagabond, get a look at these two following links:

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Inexpensive Panel……..part one.

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Inexpensive panel…….part two.

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If you would like to read a story about Andy Elliott PhD arguing with ww the A&P about instrument choices, look at this one:

“William, you ignorant troglodyte”…….(instrument options)

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The story below has comments on oil pressure errors in electronic instrumentation. That part is 2/3rds of the way down at the picture of the Corvair/701.

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MGL vs Corvair ignition issue

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As you are looking at parts of the oil system, I have reprinted the numbering system of the parts in the oil system for reference here:

Rear oil case group (2000)

2001- Rear oil case casting

2002- Rear oil seal

2003- 5/16 hold down hardware

2004- 3/8 hold down hardware

2005- Case to block gasket

2006- Harmonic balancer

2007- Balancer bolt and washer

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Oil pump and regulator group (2100)

2101- Oil pump assembly

2102- Oil pump gaskets

2103- Oil pressure regulator piston

2104- Oil pressure regulator spring

2105- Oil pressure regulator plug

2106- Plug washer

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Below is a good article of flight ops with comments on oil pressure indications:

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Thoughts on cold weather operation, minimum oil temps, etc.

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Below is a short guide on what oil to use:

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Notes on Corvair flight engine oils.

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Below is a visual reference to where we take the oil pressure on the Corvair engine:

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Gold Oil Filter Housing, Standard and Reverse

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Below has notes on how the pressure bypass works:

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High Volume Oil Pump

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Have a pleasant and productive evening.-ww

10/23/201310/24/2013

Cessna’s Chinese adventure a failure.

Builders,

3,000cc PC Cruiser builder and Aeronautical Engineer Sarah Ashmore shared the following press release:

“Cessna President and CEO Scott Ernest is signaling that Skycatcher, the company’s low-cost, Chinese-built light-sport aircraft, has been relegated to the history books. “There’s no future,” Ernest said when asked about the aircraft at a Cessna press conference Oct. 21 at the NBAA convention in Las Vegas. Asked if that meant the project would be discontinued, he replied, “No future.” Skycatcher was launched six years ago with great fanfare by Ernest’s predecessor, Jack Pelton. Offered at an introductory price of $109,500, the aircraft attracted 720 orders worth more than $75 million in the first three weeks after launch, and backlog ultimately topped 1,000. But the project was bedeviled by manufacturing problems at its Chinese partner. Cessna also was forced to raise Skycatcher’s price, which caused its backlog to evaporate. Ernest was more upbeat on two new signature projects at the aircraft builder. The Citation Latitude mid-sized jet is on track to make its inaugural flight in the first quarter of 2014, and the Citation X — billed at the “world’s fastest civilian aircraft” — is expected to win final certification in March.”

In with a big bang and out with a whimper, thus ends Cessna’s 162 Skycatcher, an aircraft that was promised to set great standards in general aviation, ends up never even getting to heavy production in spite of having 1,000 deposits.

Note that the reason for the failure is: “the project was bedeviled by manufacturing problems at its Chinese partner” . Where is all that Chinese workmanship and craftsmanship now? Please note that this project, specifically shipping it to China, was the brainchild of the former CEO Jack Pelton. In case you are wondering what that guy does for a living today, why of course he is head of the EAA. Does he sound like the person who really has his finger on the pulse of General Aviation? Really understood traditional American aviation values? Absolutely not. Pelton was willing to sell out all the craftsmen who worked in Wichita for cheap Chinese labor if it could make a buck. If you work for a living, and you are an EAA member, you need no further proof that if there is a corporate dollar to be made, your interests, skills, support of our organization, and your respect for your fellow working Americans mean nothing to him.

So Cessna finds out that they should have had these planes made in the USA. The corporate elite will blame the 2008 economy, but it is fair to ask what part of our economic troubles and slow comeback belongs to all the CEO’s like Pelton who shipped our manufacturing base overseas for their own profit. (These are the people who can’t understand why a guy who had his skilled craftsman job outsourced in 2005 and now works in a $7/hr service job finds taking his family to Oshkosh unaffordable.)

And let us not forget the 1,000 wealthy buyers who certainly didn’t care where their new $100K toy was made, as long as they got to have it. We are all forced at times to purchase some imported things from places we don’t like, but a person who can buy a $100,000 toy with discretionary income isn’t forced to do anything. If you buy a pair of imported sneakers once a year, you are not giving away the same jobs nor fueling the trade deficit like a guy buying a Skycatcher. I am sure plenty of these 1,000 eagerly awaited delivery while driving around in imported cars with “take back America” stickers on them. If they don’t care that their imported Cessna would be built by $2/hr labor in a police state while the unemployment lines in Wichita got longer, then where do they draw the line? If Jack Pelton had struck a deal with Bin Laden’s family to make Skycatchers at the family run IED plant in Pakistan, I am sure that 50% of the ‘patriotic’ 1,000 buyers would have asked “can I still get my Skycatcher this year at the same price?”

If I seem to be harsh on this, it might just be that you missed my long standing and vocal hatred of the C-162. When the plane lost both the prototypes in spins that Professional test pilots could not recover them from, I was glad to question if this plane was right for student pilots; When the EAA accepted samples to fly young air academy students in, I was among those that said you can’t tell a 15 year old to study and become an engineer if you show him a plane built elsewhere, and tell him he will never have a job producing them; I have pointed out countless times that there is no such thing as Chinese business ethics and quality control when it comes to making cheap things for export.

So, who will make America’s light planes? You will, the working American, just as you have always done. In 1946 Cessna went from war production to making 30 C-120’s and C-140’s a day, without any issue at all. The greedy corporate scum like Pelton had 6 years to tool up and they couldn’t hardly make 30 aircraft per year in China. The only important difference is that the Cessna ownership in 1946 respected their workforce of Americans, and 60 years later Pelton had all his faith in the best $2/hr Chinese workers he could buy. Moving forward, it is clear that Cessna has now abandoned the “affordable” aircraft market. This makes no difference to any homebuilder. In 1946, Cessna was something of a partner to American labor in producing that generation of affordable American aircraft. Today, they have proven to be a worthless element. Each of us, developing our own craftsmanship, will work in our own one plane factory and produce our own aircraft. This is how American labor will build this generation of affordable aircraft. We don’t need cheap labor in China, we don’t need greedy CEO’s and we don’t need any membership organization that is headed by a person who fails to understand this.-ww.

10/20/201310/20/2013

22 hours until CC#27 sign up closes.

Builders,

Here is your last official notice on CC#27. While the frequency of notices resembles a PBS fund drive, I want to say that we always have one or two people who miss the notice and sometimes the dead line. Don’t let this happen to you. If you are sitting on the fence, we are getting to the wire. The sign up for #27 has been open for 100 days: you now have less than one day left to sign up. Click on this link for more info:

50 hours until CC#27 registration closes.

10/20/201310/20/2013

CHT part #5, flight data from Zenith 750

Builders,

Here is some very detailed flight data from 2,850cc Zenith builder/flyer Jeff Cochran. It is a very good and useful piece of data collection, with many fine points included. I took more than an hour to examine the charts in detail. Jeff’s accompanying letter had a lot of good flyer feedback in it also. He is straight forward and methodical in his evaluation to fine tune his specific installation. I share with builders some larger perspective to put this data in a context where you may find it easier to appreciate.

Jeff and his lovely wife at CC#16. They have attended many colleges. Jeff ran his engine at CC#19, and will likely flying it back to CC#27 for it’s public debut in front of fellow builders who fully understand the achievement of completing and flying your own plane.

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For a little background on Jeff and his plane, read the story by clicking on this link:

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

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One of the things that came to mind when looking at Jeff’s data was the early work that Mark Langford did in data recording in his KR-2S. (Mark was the first pilot to be awarded The Cherry Grove Trophy in 2008) Eight years ago Mark was one of the first guys to publish this kind of information from his Grand Rapids unit. It was read by many builders, and was a unique resource and sparked a lot of discussion, and also squashed a lot of pet theories among the internet armchair opinion crowd. Let me use the photo below to illustrate an interesting distinction between the data sets:

Above is Mark Langford’s plane with the cowl off in a photo from Corvair College #16. The airframe and the engine installation were unique in many ways. The plane was built as a personal expression of his creativity. Several other KR’s followed Mark’s build and utilized ideas that worked on his plane. Since this segment is focused on CHT, look at Mark’s cooling, a twin ‘plenum’ style system that worked well in his plane. His cowling was one he made a mold for, he used a rear starter and belt driven rear alternator, along with a remote cooler. These ideas served him for more than 1,000 flight hours in his KR, however some of these ideas would have limited applicability on other airframes. The 5th bearing on this plane is the same design I am using on our Wagabond, but almost all of the other subsystems on the Wagabond are common to our standard 601/750 installation. The Kr is a small fast aircraft that operates in a different flight envelope.

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What makes Jeff’s data unique to me is that it is all gathered around off the shelf parts on a very popular airframe. KR airframes are highly individual. The have a choice of airfoils, wing areas and spans, different landing gear, fuselage lengths and widths, and several canopy styles. By comparison, no such variation exists with Zeniths. What one builder learns can be directly applied to another’s aircraft with predictable result. Virtually all Corvair/750 builders utilize standard parts from our catalog, and assemble them according to our installation manual. Additionally, a 750 is the largest and slowest climbing aircraft Corvairs are commonly used on. One can be reasonably sure that anything that works in a Corvair/750 aircraft cooling/cowling system will also work on any faster smaller Corvair powered airframe, whereas the reverse is not frequently true.

In Jeff’s letter he references comparing notes with Gary Burdett. If you have not seen it, we have pictures on this site and his story is at this link: Zenith 750 Flying on Corvair Power, Gary Burdett, Illinois . Because their two airframes and engine configurations are very close to each other, They can utilize shared information to fine tune each of their planes. This goes further than just having a cowling in common. Details like both aircraft having a gold oil filter housing means that data like oil temp is taken at the same spot on both engines, giving very direct comparisons.

This effect is true for all Corvair/Zenith combinations to a degree that is not possible with individualized aircraft like KRs and to a large extent, Pietenpols. Both of those airframes have active and well run internet groups. Zenith runs it own gigantic webgroup for all of its builders. To give builders working with the Zenith/Corvair combination a specific spot where they could directly exchange data and notes, we set up a specific discussion board just for them. You can read about it by clicking on this link: ‘Zenvair’ Information board formed . The quality of discussion there is very high for several reasons. It is an invitation only group and it is very effectively organized and moderated By Phil Maxson. You can read about phil at this link: Guest writer: Phil Maxson, flying a 3100cc Corvair in his 601XL. Jeff, Gary, Phil and other ‘Zenvair’ builders can directly work with each other in a setting where everyone is a serious builder.

The two links below are the Data that Jeff refers to in his letter. Interesting to have independent confirmation and data to say that the alternator location doesn’t make much of a difference in cooling. We sell the front alternator (group 2900) and Dan sells the rear alternator (Group 2950). For many years people speculated that moving the alternator to the back would cause a huge reduction in temps. Both Dan and I told people this wasn’t likely because non-plenum cooling systems with round inlets are very good about sharing all the incoming air no mater which hole it arrives through. Jeff’s numbers confirm this and show the limitations of ‘eyeball & theory’ vs accurate back to back testing.

Many people who have never met me picture me as an opinionated zealot advocating some type of ‘my way or the highway’ mentality, unable to change perspectives. While I do have principles that I will not compromise on, 25 years of working on planes has given me the perspective to understand what is an issue of principle and what is just a matter of preference.

Many closed minded people act like zealots simply because they don’t have the experience to differentiate between these two. Picture the guy who frequently says “That will never work”; He is proven wrong by the first guy who makes a trip around the pattern with the idea. Conversely, when a guy says ” might work, but I prefer not to do it that way because….” he is speaking from experience. On matters of preference, I am open minded. I have a 5th bearing design and sell front alternators, but our production engines feature Dan bearings and mostly rear alternators. I assembled both Jeff’s and Gary’s engines. They are very similar 2,850s yet one has a Dan bearing and one has a Roy bearing. These are all matters of preference between proven parts. I am if favor of builders making educated choices. The operative word ‘educated’ starts with real data like Jeff is presenting here. -ww.

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Jeff’s data charts:

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CochranPDFGraph1013 Graph Link

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CochranXL101813 XL worksheet link

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Jeff’s Letter:

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“William, Since you are doing all of the CHT and cooling articles, I thought I might update you on my progress.

I have dropped the bottom of the cowl so that I have almost 4″ between the bottom edge of the firewall and the bend in the cowl bottom. By my calculations this gives me a 2.4 to 1 ratio. I still want to up this a little. This is very close to the set-up Gary Burdett is running. We should be almost exactly alike now with one or two exceptions. I went ahead and ordered and installed the rear alternator kit from Dan. The front bracket is still in place just in case I need to go back. I am also flying without the leading edge slats. My inlets are 5″ and still raw cut edges with no ring inlets.

Sensor set-up has been changed. For a while I ran a thermocouple in each of the thermowells like the GM thermistors and a 10mm ring on the thermocouple bolt. I also had a 14mm ring on the corresponding plugs. So three sensors on cylinders 1 and 6. The plug was always the highest, the bolt the lowest with the thermowell location in the middle. I discontinued the two bolt locations and moved those sensors to plugs 2 and 3. Somewhere I had heard that cylinder 3 was always the hottest, but my data really does not support that as far as the plugs are concerned.

My Dynon D180 saves data on almost every possible parameter you can attach a sensor for. I download the file after every test flight. The first page of the attached workbook is the total raw data. On the second page I delete all of the data that is not really recorded (the Dynon seems to make up data when no sensors are attached). Then on the short version, I delete everything I am not interested in at this time. I chart the CHT’s and since the alternator move the electrical data. I have attached the excel workbook file. But just in case you really are the computer troglodyte you claim to be (which I really doubt) I have converted the CHT chart to .pdf.

The alternator move as you have often said did not seem to make much difference in cooling. Logically that was so hard to believe I just had to prove it to myself, You probably have realized by now that some of us are hardheaded that way. Cylinder 6 is always much cooler that cylinder 1 so I tend to concentrate on cylinder 1 numbers. Since the 380 degree number has been posted by you and I have seen it on the car sites also, I set my goal of try to keep the temp measured in the cylinder 1 thermowell (where the car was measured) as my normal max goal. My current set-up has been achieving that limit. I still plan to smooth and ring the inlet some time in the future.

I’m still planning to fly to Barnwell (weather permitting). Either way, see you there. –Jeff”

10/18/201310/18/2013

CHT Part #4 more notes

Builders:

I received an email from a builder that gave me a moment to pause and think about communication, and what people are willing to read into things. The letter was sent by a good guy, and I have deleted his name because I want people to focus on the comment, not who said it. Here is the sentence from his email:

“In view of your modification of the inlet size for the Wagabond, would you recommend I do the same on a standard two-piece nose bowl for my plane? Did you make the mod preemptively, or was the Wagabond running hot? Thanks in advance”

Now, all this week I have been writing about cooling, and specifically linking to many articles that I have written in the last 20 months. The photograph and caption listed below is in a story that was directly linked to a few days ago. Read it and see if you think I the Wagabond was running hot as the letter writer asks:

Above, a real world proven Corvair system, the Wagabond cowl. Note that the air inlet is a simple 4.875″ hole in the cowl. This aircraft has flown at the record gross weight for Corvairs, it has always lived in Florida, it has a very large airframe with plenty on drag to spare, and yet it never ran hot, even with a front alternator and no inlet cooling rings. Why? because Corvairs have excellent cooling. builders can either utilize this success or they can ignore my suggestions. If they chose the latter and it doesn’t work, they rarely see the problem as a people issue. For some reason, a fraction of builders will focus on stories of people who has trouble with one-off ideas rather than looking at all the people who are flying proven ideas without issue.

This while series started because I was angry about people offering the unfounded opinion that Corvairs inherently ran hot, and that the cowls we offer and the way we teach people to cool the engine does not really work. Over the last several nights the stories I have written have been to counter these ‘opinions’ with facts and data, and offer links to show that this cooling is not an issue with Corvairs. The last sentence in his note indicates to me that some people are not really reading what I have to say, and my words are competing with a predisposition on their part to still believe that there is something wrong with the cooling as we build it.

I don’t blame the letter writer. He is exposed to many people talking about Corvairs, and at times it is hard to keep sorted out who has an ‘opinion’ and who has been testing and flying. This is why I was annoyed in the first place with people who have never owned a flying Corvair spreading rumors that “Corvairs need 6″ inlets”. On one hand it is just a lot of background static, but I am of the opinion that some of it sticks even when the recipient doesn’t consider nor remember the source. If you are new to a subject, be very discriminating when you choose to listen to people. Adopting perspectives, even partially based on false opinions it at best, a tremendous waste of time and energy.

To me, the really ironic thing is that their are other alternative engines that really do have cooling issues that are very hard to solve. The Corvair is nothing like that. Yet the ‘buy it in a box’ imported engines with actual cooling issues probably generate less internet discussion than the Corvair does on this topic. Part of the reason is that the people buying those are largely shopping for an appliance, and people coming to corvairs are supposed to be here to learn about a machine. The latter should generate more discussion, but talking about things is not the same as learning, especially when much of the conversation is opinion, and when fact must compete with rumor during the phase where the new builders understanding just developing.

The post I put down last night was number 365 since we started this blog. Give or take, that is a quarter of a million words. If I tasked you with typing a 250,000 words that were educational and entertaining or gave you the option of building a two place kit aircraft, which would get done first? I type about 20 wpm, (not counting time spent staring at the keyboard) so I could build the plane much faster. I still consider the time well spend, under one condition: People actually read the content.-ww

10/18/201310/18/2013

CHT part #3, Letters, notes, sources and inlets.

Builders,

Here is another block of information on CHT and cooling, along with data from flying pilots. This is a collection of notes and loose ends that adds a little more dimension to the first two parts.

Above, The Wagabond nose bowl last night about 3am. I have been having a run of insomnia lately, and have been dividing up the hours in the middle of the night between writing, doing a little work on the Wagabond and reading Morris’s Colonel Roosevelt, a rich biography of TR from when he left the White house until his death. When I am this tired, I don’t make customer parts, but I will work on my own basic stuff like nosebowls. Last night it was more than 70F in the hangar. Not a bad temp for glass work. I bonded in the inlet rings seen above. They not only give the cowl a much better look, they are also functional. A lot more air will flow through a 5.125″ tube, even a short 1.5″ long one, than will flow through a 5.125″ hole in a flat plate. These rings are made out of PVC pipe, but you could actually make them out of just about anything. This is the biggest size I think any Corvair needs, even on heavy slow climbers like Zenith 750s. This original one piece nosebowl is dimensionally the same as the two piece models we sell today. It has an altered line where the sheet metal of the cowl meets the nosebowl to make it fit the Wagabond better and the ‘tunnel’ in it is the beginning of the shape that flows into the J-3 airbox/filter that the plane is set up to use.

Above, a detail look. The white ring is PVC, it is bonded in with West System epoxy thickened with silica and flox. The section of paint stick and the sheet rock screw are just working as a clamp. If you look close, you can see that the tube flares out slightly on the ID near the end. It isn’t needed, but it will not hurt. Epoxy theoretically doesn’t stick to PVC, but it will get a mechanical bond if the surface is rough enough. This nose bowl is 10 years old. It may look a little rough, but well made glass parts hold up even on hot engines and over long lives. If you look closely, the marks show that it was vacuum bagged into our mold. the part had the image of the bagging plastic in many places.

Above, a bigger view. I ran 3 sheet rock screws through the part to pin it to the table after I covered the table top in plastic sheeting to prevent sticking. The screw holes don’t matter because they are in the section covered by the spinner. The two inlet rings are being clamped down by the sticks until they hardened. You can immobilize many things to a wooden work bench this sheet rock screws. Again, 5.125″ is probably too big on all except the slowest climbing planes in hot weather. Inlets size doesn’t cool by itself, it has to be matched with outlets and good baffling.

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Mail and comments:

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Letter from 2,850cc 601XL builder and flyer Ron Lendon:

Ron with his plane at Brodhead 2012.

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WW, it’s not that I don’t enjoy the reading I miss the succinct data and would like to have a place to quickly look it up. Perhaps in my spare time now that the plane is flying with the correct carb. No I didn’t volunteer to do it. The calibrated CHT gage you allude to, is it available to those of us with short attention spans also? I have the Westach gage and rarely see the CHT temps go above 350F on hard climb in the more temperate climate we have here in Michigan. I’m using the ring type connection at the GM location.”

Ron, I looked on Ebay and other places to see who was selling Mil.surp. gauges but didn’t find anything noteworthy. I found mine at the Oshkosh flymart. Get a look at this link, it is to Dakota Digital, a company that makes all their stuff in the USA. http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=347/category_id=248/home_id=59/mode=prod/prd347.htm

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Letter from 2,850cc CH-750 builder Blaine Schwartz:

Click on: ( Zenith 750 Builder Blaine Schwartz )

“William, Thank you for such an informative essay! Carl Sandburg once wrote: “Experience is the greatest teacher”. You are a first-class example of proving his premise. Blaine”

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Letter from 3,000cc PC Cruiser builder Sarah Ashmore:

“I find it difficult to understand why anybody feels they need 6 individual CHT readings on a Corvair. Lycomings and Continentals have a CHT on each cylinder because each one is truly independent and subject to different cooling and heating rates. The Corvair is one big block of aluminum, a material which conducts heat rather well, so it should be fairly uniform in temperature regardless of what is going on in the cylinders. One on each head is good enough for me and I have already purchased the special size bolts along with the other hardware for the engine build. And cooling is not something I like to do the hard way either. My variation on the Personal Cruiser will have a 30″ wide firewall instead of the stock 22″ but I have your generic nose bowl and a set of generic Weseman baffles all ready to go on it. All I have to do is make sure I follow your recommendations on the cooling air exit and I would expect the test flights to have no surprises with regards to engine cooling. There is enough experimental in my aircraft already so I choose my innovations wisely. A good pair of articles in a long line related to engine cooling.”

Sarah, there are also a lot of certified planes like C-150s and 152s that don’t have any CHT at all. 6/cht-6egt combos mostly appear as an option on big injected engines in fast certified planes like Bonanzas, where owners are trying experiments in extreme leaning and early top end replacement. Although Dan Weseman has a 6/6 combo on his plane, just the other day he was saying “what is wrong with a little too much cooling?” implying that no one is setting a record here, so why not sacrifice a few mph cooling drag to have an engine that always runs very cool. It fits in with your idea of leaning to the proven side rather than the edge of the envelope.

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Letter from 2,700cc 601XL builder and flyer Dr. Gary Ray:

Click on: ( 601XL-2700cc Dr. Gary Ray )

“William, Thanks for this post. I read and re-read everything but this brings all of the temps, measurement locations and expected results into one post. I have my 601XL-B setup as you have shown and I am experiencing the same results. Until recently, I have taken all CHT’s from beneath plug #3 and #4. The highest temp I have ever seen has been 430 F on its maiden flight when I only measured plug #3 , otherwise it can get to 410 on high heat days during a 90 mph sustained climb. I now record temps on both sides from the bottom #1 & #6 locations. During the last 50 hours I am seeing a maximum temp of 315 F on the worst days and a spread between sides of less than 10 degrees. Measurements show approximately 80-90 degrees lower temperatures between the top plug position and the lower GM position. The gauge is a four channel MGL device for CHT and EGT’s and it produces comparable results to the temperature compensated analog meter I had used before. It reads about 10 degrees higher and has a thicker washer type thermocouple which likely accounts for the slight difference. In cruise at 3000 rpm, 9.75 degrees at the tip Warp Drive, 21.5 MP, 65 OAT, CHT’s read 270 degrees. EGT’s taken at 12 inches downstream from the last exhaust port are 1200 to 1300 and will go higher if leaned more aggressively which I do not do.
Current Set Up: Maximum advance on the timing is set to 30 degrees, 100LL fuel only, Inlets size 4.75″ with inlet rings, Outflow is 3.5″ x 24″ which is 2.4X inflow area and the bottom edge is rounded. Metal tape over cowl hinges above plenum and tight baffles. The Niagara oil cooler reduced maximum oil temps by 30 degrees (now 210F). Normal climb is 90 mph. If I see temps near 310 F , I increase air speed by reducing my rate of climb which seems to work.
It is nice to know that there is such a large margin over normal operating temperatures before overstressing the engine. The engine runs with a very low level of vibration. Just how low is really apparent when I am in dead calm air. This is when I start patting myself on the back for choosing the right engine.”

10/17/2013

50 hours until CC#27 registration closes.

Builders:

We have a shade over 48 hours until we close the registration on CC#27 which will be held in Barnwell SC November 8-10.

CC27 – https://corvaircollege.wufoo.com/forms/corvair-college-27-registration/

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The Event also has it’s own Face Book Page:

https://www.facebook.com/CorvairCollege27

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Below is a link to a story I wrote about the specific skills builders learn at colleges. Read it and decide if you would rather learn these things slowly at home, or head to the college and have me teach them to you personally in one weekend. You can do it either way, but I an assure you that it changes the way you see yourself, from mere owner to builder and master of your Corvair engine to know these skills. It is hard to make an argument against learning them sooner rather than later.

Basic Corvair College Skills, examples of learning

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Below is a link to my story about the “Cherry Grove Trophy”, which we present to the outstanding Corvair Aviator of the year each November. In 20 days there will be a new name on the Trophy, and a fresh presentation made at Saturday night’s dinner. In other branches of aviation, the awards often go to the guy that wrote the biggest check or had the most political influence. In the land of Corvairs, we are not polluted by corruption like that. Our Trophy goes directly to the individual that set an outstanding example and gave back to others now building. Barnwell is the setting where you can meet these builders in person and understand that your place is beside them, In the Arena. Reading a membership magazine featuring aircraft no working man can afford, written by editors who would consign and condem you to be only a spectator is the antithesis of this. Read this story, contrast it to most industry magazines, and then decide for yourself: Spectator or Man in the Arena?

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The Cherry Grove Trophy

Blast from the past, CC#19, Barnwell, 2010. Builder Jeff Cochran stands with his running Corvair. Today this engine is flying in his Zenith 750. He is planning on flying it back to Barnwell for CC#27. Progress is made by deciding that the time has come to advance your own dreams. You must choose this, it doesn’t happen without your personal action. If I am ever going to write your story about flying your plane, you must take action to start this.

” (2010)- Zenith 750 builder Jeff Cochran of Alabama supervises the run-in of his 2850cc Corvair, above. 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.”

10/17/2013

Pietenpol Mount on airframe

Builders,

Piet builder Mark Chouinard sent in a photo of his Corvair motor mount on the front end of his plane. The airframe exhibits outstanding craftsmanship, and looks to be in the “light at the end of the tunnel” phase. From this point forward the pace of work tends to increase.

When new guys set started they find it hard to visualize how much more productive per hour they will be in the second half of the plane. Your skills will be far better, you will find a work schedule and rhythm that fits your life, you will have many trusted fellow builders to share info and enthusiasm with, and with enough persistence, you can see the light at the end of the tunnel.

Mark’s plane is a traditional Pietenpol with a number of nice details. The landing gear combines traditional wire wheels from a straight axle gear with J-3 style independent suspension. Disc brakes are modern but appropriately sized. This view gives a good look at the Pietenpol’s structure. Mark has wisely left off the outter skins on the front of the fuselage until everything is built and rigged inside. The Gray powder coated Motor mount we made for him is one of our “High Thrust line” motor mounts. Below are some direct links to Pietenpol stories in our archives. The first three explain the concept of a high thrust line mount.

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Pietenpol Motor Mounts, P/N 4201(C)

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Pietenpol Products, Motor mounts, Gear and Instalation Components.

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Pietenpol Power: 100 hp Corvair vs 65 hp Lycoming

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Three Pietenpol Motor Mounts

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Making a House Call on 1,000 Hour Pietenpol

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New Pietenpol #3, Mike Groah, Tulare, California

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New Pietenpol, Gary Boothe, Cool, Calif.

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Pietenpol review in pictures, 15 more Corvair powered Piets

From our Brodhead 2013 coverage: “After the Forum, we conducted a Tailgate Tech Seminar. Piet builder Mark Chouinard, extreme right, extreme tall, listens as I answer questions. Mark picked up one of our high thrust line Piet Mounts for his project. Jim Boyer of California picked up another one at Brodhead for his Piet. That rounds out the first 10 of these new generation Mounts. While I have previously made Motor Mounts according to the original drawing, all of our Piet mounts from here forward will be high thrust line models.”

10/16/201310/16/2013

Corvair CHT, letters and notes.

Builders:

We picked up several letters from friends on this topic. Let me share some of them and offer a follow up on the story.

Zenith 601XL builder and flyer Ron Lendon wrote:

“And after all that reading I’ll be dipped if I can find your recommendations for the temperature range your followers should be shooting for. Try putting those details in too, OK?”

Ron, for a guy who made his own cowl and experimented with carbs, I would have guessed that you would have liked reading the information. The topic was the measurement location and test tools, not so much the values. For people with busy schedules and short attention spans, The numbers:

GM Factory limit, measured on bottom of head: = 575F

Highest temp I have personally seen in a Car, measured on bottom, without engine damage = 575F

Highest sustained temp I have personal seen on a CHT in a plane without any damage to the engine = 480F, measured on bottom of engine

Highest temp on bottom of engine that builders should consider tolerable before stopping to rework cooling system = 420F

A reasonable goal temp in a hard climb that will still have a very wide margin of safety = 380F, measured on bottom of engine, easily achievable with our existing cowls and cooling designs, even in large planes.

Highest Temp that Dan Weseman saw on bottom of engine in full air combat maneuvers in 3100cc “Wicked Cleanex” = 375F

Typical Max climb/ 5 gal/hr cruise temp numbers in well prepped Zenith 601on 80F day = 375F/320F

My target goal, measured on bottom of engine, for gross weight Vx climb in 3000cc Wagabond, 100F day, 5″ inlets, 60mph, 1,600 lbs = 350F.

Lowest cruise temp recorded for a plane with a full cowl, measured on bottom of engine, Chris Smith 3100cc “Son of Cleanex” = well below 300F.

Lowest cruise temp recorded for a plane with a J-3 cowl, Jim Weseman, 3100cc Celibrity biplane = 250F

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Above, Phil Maxon’s 601XL, finished in our hangar in 2006, flies over the Atlantic Ocean near Ponce Inlet FL. This aircraft was one of the first 4 Corvair powered Zeniths, yet is has never had any cooling issues. Corvair Cooling, especially on airframes like Zenith XL’s is not a mystery. Anyone who chose to follow our directions and used our designs did not have to be a pioneer. If you want your plane to work, just make it a clone of successful aircraft.

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For readers with a little more time, get a look at the following links to stories I have written. I found them all simply by searching “Cowling” , “Cooling”, and “CHT” in the search block at the top right side of this page. If you are only going to read one story for right now, make it the last one, because it highlights the difference between measuring the CHT under the plugs and below the engine:

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Cooling with J-3 style cowls. (Pietenpols, Cubs, Biplanes, etc)

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Corvair Cooling, Three 2007 examples from our hangar.

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Corvair Cooling, something of a human issue…..

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Corvair Cooling

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http://www.flycorvair.com/pietengineissue.html

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Measuring Cylinder Head Temps on Corvairs.

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Right here and now I am going to make a very important point: I could put an engine on the run stand, hook up two of the finest CHTs, fuel the engine with pure ethanol free 94 octane gas, have it be ice cold and get ready to start it. Then I could reset the timing from 30 degrees total to 44 degrees, (a number that people without timing lights often think “sounds good”) Start the engine, and take it to 2,700rpm.

It would take more than 3 minutes for the CHT to exceed 400F on the gauge. Long before this, the detonation would begin, and within 30 seconds of it really knocking, (which would be hard to hear over the prop,) the engine would blow out at least one head gasket, and crush down the ring lands on several pistons.

I could then honestly report “The engine had never exceeded 400F.” I could give many examples like this, and then we could have a lot of internet people offer opinions about the cooling system design we use, and some car guy is going to offer the “expert opinion” that the cowl needs 6″ inlets. If you want to learn something in aviation, the discussion is going to have to be held at a higher level than that.

CHT is not something that can be discussed as an issues divorced from other operational parameters. I have seen people waste incredible amounts of time trying to solve a “cooling problem” who have not bothered to check any of the basics.

I have been doing this for a long time, and I still have no idea why some people get to the point of having 5 years of work and $30,000 in their aircraft project, but they refuse to drive down to their local auto parts store and buy a $39 timing light.

About a year ago, a guy contacted me who bought an engine I had built for someone else in 2005. He had it ground running on his plane. When I asked him what the timing was set at, he said he had no idea, he just assumed, without a single word to confirm this, that I had set the timing before mailing it to the original owner six or seven years earlier.

I explained that this was a very poor assumption, that even if I had, there is no telling that it wasn’t changed by the first owner, or bumped as it went in or out of the two airframes and was shipped around the country. I pointed out that if I said I unloaded a firearm before selling it to someone else 7 years ago, I would hope that no one would never say to me “I can point it at people today because you unloaded it half a decade and three owners ago.”

About a month ago I heard from the same guy, The engine still was not running evenly on both ignitions but he still had not checked it with a light. If someone presented me an engine that had a years ground running on it, but had never had the timing checked, I am going to flat out say that I would not fly it without tearing it down. Why? because you can check things the easy way with a timing light right away, or you can check things later the hard way with wrenches. Or of course there is the third option, which is just say “I am sure it didn’t hurt anything, It will be alright”

‘Sprint’ builder Joe Goldman wrote:

“William I as am not building my engine I would feel comfortable with 6 cht’ too know what is going on with each cylinder. Does the stock location average temps or would it indicate a particular cylinder over heating. You would not know which one, then how do you locate the trouble.”

Joe, we are friends and you know I think you are great, but lets get a little more thoughtful on this one. First, why are you not building your engine? If the goal of asking me a question is to learn something, then let me offer that building your own engine is the best way to learn many things. Honestly, what are 6 chts going to tell you that 2 are not? Lets say that flying along at 5,000′ and the CHT reads very hot. What are you going to do? Land, that’s what. If your right side CHT indicates an excessive number, please explain to me what knowing if it was #1 #3 or #5 is going to do for you at 5,000′. I have said it many times and many ways, but please know this well; You detect issues in the air, you land. Diagnosis is always done on the ground. The only guy who argues against this is the one who is going to rationalize some reason to keep flying. Each CHT sender cost more tan a Raytech thermometer. If the plane isn’t running right, land and use tools on the ground to look into the problem.

Besides, if you build and equip your engine correctly, you are not going to be flying around looking at issues in the air. Stop for a minute and honestly tell me what is going to happen to an engine, in flight which is going to make an individual cylinder suddenly go up in temp? If you were looking to tell which individual cylinder was causing an issue if your engine started running rough, you are a poor decision maker, and you need a better flight instructor. Any skilled pilot will tell you that the first thing you look for when your aircraft runs rough is the nearest airport. -ww

10/15/201310/15/2013

Cylinder Head Temperature measurement

Builders;

In this story I would like to address CHT (Cylinder Head Temp) measurement on Corvairs. In the 20+ years I have been working with Corvair flight engines, I have written a great number of informative posts and stories on this topic, and I have also covered this in stories on cooling systems, instrumentation, human factors for lower time pilots and how CHT relates to detonation threshold.

My comments on these topics can be found in our manuals and on both websites. The information we have shared is from personal measurement on several of our own aircraft, dozens of test engines in extensive ground runs, comparative instrumented engines, and a data from a number of experienced Corvair powered pilots Like Dan Weseman and Woody Harris. All of this has been collected and correlated with my professional A&P perspective, and often discussed at great length with other trained professional aircraft mechanics like Gus Warren and Arnold Holmes, whose experience includes extensive Corvair flight time, in addition to many certified aircraft engines. My data includes many aircraft that worked well, and a handful that didn’t. It is big picture, not myopically gleaned from looking at one or two engines, listening to stories and jumping to a conclusion.

I do not consider myself ‘brilliant’ about this topic. The value of my perspective comes from simple observation of data over a long period of time, working with builders and being in the best position to gather all the data. This is the opposite of just following a few stories that seem to support a pet narrative. Part of what motivates this story is hearing from builders who have been told a number of myths about Corvair CHT info.

One builder was told he “Has to have 6″ air inlets.” Others have been told that the GM CHT locations don’t work. None of this is supported by observed data, it is opinion from people who just think their pet theory is right. The myths are not always malicious in origin, but well intentioned and malicious myths are both myths just the same. Two very prolific sources of this information are people jumping to conclusions based on little experience. If someone has never soloed a Lycoming, Continental nor Corvair powered plane, they can still have an opinion on CHT, it just isn’t worth sharing with builders who need factual, unbiased data.

Above, a Lycoming O-320 (160hp) cylinder that I own. The 320 is the most respected and prolific light aircraft engine ever built. You are looking at the bottom of the cylinder, the 320 has both the intake port (left) and the exhaust port (right), on the bottom of the head. The arrow points to the CHT probe location. One of the people telling builders his view that under plugs was the only place for CHT obviously didn’t know that all Lycomings use this location, which is very much like the GM Corvair location. For most Lycomings, the CHT limit is 475F. While I am thought of as a Corvair guy, Our hangar also contains a C-85 and an O-290, and parts of many other aircraft engines. My perspective comes from broad experience and spending time with aviation professionals with far better backgrounds.

A mechanic may be clever with EFI or experienced with vehicles imported from the fatherland, but if they have never turned a wrench on nor flown a Lycoming powered plane, their perspective is myopically limited. I really don’t know a lot about modern car maintenance, but I do know a fair amount about planes, and I know enough about both subjects to say that knowing one does not qualify you in the other.

On the table next to the cylinder is a 50 page Lycoming operations manual. You can down load it for free off Lycomings website. Every aircraft mechanic I know owns a copy and is familiar with the data inside. It is a great book, and even as a Corvair guy you should read it. Quite often, people will say things that are directly against the experience in this manual, even when they are Lycoming owners, speaking of Lycomings. For example, Dan pointed out to me that Lycomings leaning operation in the book is enrich it until it runs slightly rough and lean it only until it runs smooth, exactly the opposite of what most people think. Either you are the kind of builder who is inclined to follow the recommendations of the company that built 300,000 of the engine you are running or you are the kind of guy who is going to follow a story written in Flying magazine by a guy who has never pulled a cylinder off any aircraft engine.

For several years at Oshkosh there was an alternative engine guy who’s background was car racing who liked Gear Driven liquid cooled V-8’s. He started all of his forums by writing on the board “If Lycoming made a car would you drive it?” I spoke with him a number of times and read the stuff he wrote. He absolutely felt he had nothing to learn from Lycoming, (or most other experienced sources for that matter) He doesn’t write that any more. This is because he was killed by a mechanical failure while flying his plane. It was his second major accident. He killed his passenger also. I spoke with him after the first, and I will tell you he learned nothing from it.

Another person using that same engine wanted to put it back in production, after the accident, but he was killed by a similar engine failure. I just read a nice magazine story about a very nice Australian aircraft using the same gear box. A small postscript at the end of the story said that he was killed by a gear box failure. Same magazine had a press release from a new guy who bought the gear box assets to make more of them. You don’t need a crystal ball to predict the next chapter.

Don’t have anything to learn from Lycoming? They made plenty of successful geared engines like the GO-435, the IGSO-480 and the IGSO-540. No, they didn’t make cars, but evidently being a ‘race car driver’ doesn’t qualify you to make geared engines either. People who claim that they don’t have anything to learn from the successful experience of people who preceded them tend to attract followers with the same mindset. A harmless social phenomenon when the topic is flower arranging, interior design, modern dance or fashionable footwear. When the topic turns to subjects with consequences, like aviation, builders who plan to die at home in bed with all of their great-grandchildren in the next room, tend to learn from others.

Above, the GM Corvair CHT location. Most common question: “Is it on the same spot on both heads?” Yes, because there is only one head. There is no such thing as a right or left Corvair head until we weld the pipes on the intakes, so this is on “both” heads. In 95 and 110 engines it is threaded 3/8″-16. An easy way to put CHT here is to use a 10MM spark plug ring CHT terminal and hold it down with a 5/8″ long bolt with a washer. This will work great. All Corvairs with the exception of ‘Spider’ and ‘Corsa’ high performance models had an idiot light in the dash that was tripped at 575F by a sender screwed into this hole. I had a guy who had never owned a Corvair tell me that the 10mm ring would not work because “it needed to touch the bottom of the hole” Really? the GM sending unit didn’t, and it read just the same.

For another view of a Corvair powered plane that is slow climbing, but runs cool, read this story: Gary Burdett, 2,850cc Zenith 750, now flying. (engine selection) I personally verified the temps that Gary is getting by independently measuring them in person, on his plane, at Corvair College #26. I heard from a guy who said he didn’t think it could run that cool, that both Gary’s instrumentation and mine must both be wrong. This comment came from a person who has never seen the plane nor the engine, has no idea where the temps were taken from, nor does he have a running engine nor a pilot’s license, yet he is still quite sure he is correct, unwilling to even entertain the possibility he is wrong. Some people you are just not going to reach, and that is OK. Plenty of people who stayed on land back in Spain felt that if Columbus had just sailed a little further, he would have fallen off the earth, and nothing Columbus did was going to change their minds.

Above, an eight year old photo from the old hangar in Edgewater. In the foreground, my 1966 140HP four carb Corsa, behind it Kevin’s 1965 180HP turbo Corsa. Both of these cars have factory CHT gauges. The factory turbo cars did not use a waste gate, they just had an oversized turbo and a very specific muffler, and the result was a very simple system that did not go into boost until the car had some serious rpm, the throttle mostly open and the CHT over 400F. Below this, the head dissipates the heat energy the turbo needs to make boost. The engine will not make its full output until it is up in the 500F range. Granted, they didn’t have to run this way for a hour at a time, but I have met people who don’t believe that Corvair engines were run that hot in the cars without damage. They hold this opinion even though they have never driven a turbo Corvair and seen the CHT gauge with their own eyes. I have driven 120,000 miles spread over the 4 Corvairs I have owned. At the time the Photo was taken, Kevin owned 7 other Corvairs, Grace had her 65 van, Gus had a ’67 Monza and Dave had a ’69 Monza. I felt that our ‘hangar gang’ was qualified to comment on Corvair operation. I have met many people who have never owned a Corvair with strong, but incorrect opinions about how the engines ran in cars. Explaining the basis of my observed experience to the contrary, they often stick to their opinion, they are more comfortable with any antic dote that seems support their opinion than a mountain of contrary evidence. This is especially true if the person in question is a car mechanic.

Corsa models, (140 and 180 HP) have the hole threaded 3/8″-24, same as a Lycoming. To make the 95 heads on my plane compatible with standard Lycoming probes, I have helicoiled them for 3/8″-24 threads. The probes I am using are Electronics International P-101s with A-101 quick detach fittings. They are in the Aircraft Spruce catalog on page 523.

If a guy wants to share an opinion about temp measurement that is contrary to mine, it might be worth asking what kind of test equipment he us using. If he looks at the head of an engine he did not see run and wants to jump to a conclusion, or he wants to use internet data from a builder who never set the timing with a light or is running a non aircraft carb, it probably isn’t going to be as accurate as I can collect in person.

From my tool box, top row, Fluke two channel digital type K temp meter, accurate to less than 1/2% of reading, compares two probes simultaneously, reads all common aircraft probes. Digital type K contact thermometer, 0-1,200F, accurate to 1 degree. Westach CHT, common in aircraft, not accurate source of info, but commonly quoted on net. Bottom, two Raytech non-contact thermometers. accuracy limited to surfaces that don’t have shiny finish, tends to read too high in many circumstances. OK for quick check looking for cold cylinder, but weak on data gathering. Small spark plug item: Original AC thermistor from 140/180 HP Corvair. Same part actually used on many certified aircraft such as Twin Comanche.

Above, the instrument panel in our Wagabond, in the process of being wired. The gauge in the lower right is the CHT. It is a very accurate military unit with a little stamp on the back that says “Calibrated MCAS Cherry Point.” It takes type K thermocouples and need no power at all to read, it is independent of the electrical system of the plane. There is a hole under the gauge for a left /right switch.

I like traditional gauges, and 2 CHT’s in the stock location make sense to me. You can also run 2 CHT’s in the stock location with many Glass Cockpit displays. If you want to run 6 CHT’s, then you are probably going to run them under the plugs. If you do this, know that we have gathered plenty of data to say that these will actually run hotter than the CHTs in the GM location because they actually read the temp of the plug as much as the temp of the head. They can be a little pain during a plug change, and if you are not careful, you can over torque one in a plug hole with a helicoil or a time sert in it, and the sending unit will stick to the top of the thread and extract it when you unscrew the plug. One way to avoid this is to run a copper washer, then the sender, then the plug, but this is even more likely to show the temp of the plug. I have wired plent of planes for 6 CHTs, I am not enough of a zealot about it to really care about what other people would like in their planes. Dan has 6 CHT’s under the plugs in the Panther and it works great.

In general, the plug temp on #1 will read 60-80F higher in climb that the same cylinder with a probe simaltainiously running on the bottom of the head. If anyone is speaking of CHT’s on a Corvair, and anyone comments on it without first establishing where the temp was taken and what kind of gauge was used, then they are not adding anything to the discussion. Quite often, if a builder mentions that their plane runs hotter than they would like, the first thing people like to chime in with is that there must be something wrong with the way we teach people to build cowls and cooling systems. In reality, we have people who are flying the same system successfully, so logic say to check these this first:

1) Is the timing set correctly with a light?

2) If there is a significant L/R difference, especially at part throttle, and it has a flat slide carb like an aerocarb, Elison or a Rotec, it is the carb causing this effect. Butterfly style aircraft carbs don’t do this.

3) Does the cowl have inlet rings?

4) Does the outlet have a lip on it and is it 3X the size of the inlets?

5) Is the instrumentation correct?

6) Are they the correct spark plugs?

7) Is the fuel high enough octane?

8) is it a one of a kind prop? (these frequently don’t pump much air down near the inlets)

The above 8 points are the most common factors that keep the engine from running as cool as possible. Be advised that I have seen people break all 8 at the same time and still fly their plane without overheating it. God protects children and usually fools also. If you like the image of being 100 and meeting your great-grandchildren, I suggest not trying to discover the exact statistical value of “Usually.” -ww