Paul Salter’s Panther; Outstanding Homebuilt Aircraft of SnF 2017.

Builders,

Paul Salter’s 3,000 cc Corvair powered SPA Panther was awarded the title “Outstanding Home Built Aircraft” at Sun n Fun 2017. It is a well deserved reward, going to a guy who is respected by all who know him.

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To see photos and videos of Paul, his Panther, and projects:

Paul’s Panther

Corvair Thermal Image Testing

Short Run Video; Panther.

Testing at Sensenich Propellers

Would you rather be friends with a turtle or win an academy award?

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Paul’s Panther on display at the SPA booth in Lakeland.

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Before SnF, three Panther’s in front of Paul’s hangar. L-R – Paul’s, Steve Pedano’s and Bob Wooley’s.

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Who has the hardest working Corvair? Look at the belly of Paul’s plane and see the oil streaks; This was a result of intentional inverted spin maneuvers. Paul’s plane has a Ellison EFS-3A carb, and it does not quit when inverted.  Although it doesn’t have an inverted oil system, it will not run out of pressure during brief inverted flight.  The oil is a few ounces trapped in the breather pipe expelled when the plane is rolled upright. The test was done by Bob Wooley. Read more :  Understanding Flying Corvairs Pt. #2, Hardest working engine.

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Paul’s cowl with oil access door open.  SPA/Panther Cowls and FlyCorvair KR-2 cowls are all fiberglass, all other models we work with are composite nose bowls with metal cowlings

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Above, at the SnF awards dinner.

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Compression and Detonation Testing, #2

Builders:

Here is part #2 of the series. Part #1 can be read here: Compression and Detonation Testing, #1

I am currently assembling the test motor, but a builder wrote in with a valid question: He asked why was I so sure that the motor would make flight power with very low differential compression? The answer is this: I have 28 years of experience on this, and there have been plenty of chances to see builders’ engines running after they made a mistake that blew out a head gasket. Below are two examples pulled directly off my traditional website, long ago documented. However, after our current tests, we will have sharp comparative numbers on a back to back test. For today, some older evidence that provides the basis of my understanding.

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Above is a cylinder pictured at Corvair College #20. This is the cylinder that was removed from John Neff’s engine with a blown head gasket. The commentary on the original 2011 photo says this:

“If you look closely you can see that it has molten aluminum stuck to the side of the iron cylinder. Again, this did not stop the engine from running or producing power.”

You can read the full comments here, where they have been for the last 6 years: http://www.flycorvair.com/cc20.html  The fact the ignition timing on this engine was not set with a light before it was flown was the root cause of this. This is what severe detonation does to a Corvair flight engine. A large part of why the engine keeps running is the forged pistons do not blow out first, thus the engine can keep turning and making power. 100% of original Corvair cars had cast pistons which tend to break or get holed before the head gasket fully blows. Thus Corvair car experience and opinion has no value when looking at flight engines and evaluating them for detonation. If car mechanics were qualified to work on aircraft installations, an ASE car mechanic could do an annual on a Cessna 172 engine. They can’t because the two different experiences don’t overlap very much, and in some ways work against each other.

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Above is Gary Coppen’s Corvair Skycoupe. I have been friends with Gary for nearly 20 years. He will gladly tell anyone the story of how he flew a 90 mile cross country in the plane pictured above, with ZERO differential compression in cylinder #4.

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In 2004, Gary had the plane based at Spencer airfield in north central Florida. It is a rough 2,000′ grass strip surrounded by 50 foot trees.  At the time our shop was at Edgewater airport, 10 miles south of Daytona Beach. Gary called to say the airplane seemed slightly down on power, but he had been operating it that way for 10 hours or so. I told him I would come up and get a look in a week. His solution was to fly it down to our shop. I tested it when he got there, and it has absolutely zero differential compression in #4. At the time the plane had bolt on head pipes, and instead of using the specified Clark’s C-12A gasket, he had made one, and it had caused a vacuum leak that leaned out and detonated #4 until the head gasket was blown. The plane had flown the cross country without issue, Gary just said the ROC was down from 800’/min. to 600’/min.

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These are but two of many stories I know that show the engine will run and produce flight power with a blown head gasket and zero differential compression. The secondary moral of these examples is they were both preventable.

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Beyond this, I have has cases where builders forgot to put a base gasket under a cylinder, or even missed a head gasket. I have had cases where car head shops failed to deck the bottom of the head after cutting the head gasket areas, so the cylinders ‘shouldered’ on the underside of the head. When these motors run, they let out a distinctive ‘chirp’ sound, but people miss this, even though it is audible over the open exhaust and prop. Again, if you use our parts, and follow the directions, these are not issues you will encounter. On the other side of the coin, people who don’t use timing lights, nor respect direct warnings have trouble in their future.

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Snake Season Returns

Builders,

This week brought the magic Florida spring combination of rain and warm weather that awakens all the snakes. Below is a 26″ “juvenile cotton mouth” ( they have greenish tails ) who greeted me in the workshop, and then made a bee line for the crawl space under the house. As unpleasant as chasing him was, it was better than trying to sleep thinking about all the ways he could get in, or having to worry about him crawling in the clothes  dryer hose for a little night time warmth. Living in rural Florida has things to be vigilant for, but in our neighborhood none of them involve humans.

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An interesting pattern that kind of looks like a bunny. The coloring makes me think digital desert camouflage had to be inspired by this.

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Bottom view, different pattern, green tail evident


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Topside view.

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Common tools of rural Florida, L to R ;

H&R 1871, 20 gauge 3″shell, 20″ (modified) barrel. Great all around yard tool, thumb break and powerful ejector allow opening and closing with one hand and loading with other. 6.5 pounds In an era of liability suits, it is nice to have a firearm actually designed with no safety, because you used to be able to expect people not to point loaded guns at themselves or others. Purchased new in St. Augustine sporting goods store.

Savage 24C, 1980s vintage. .22LR over 20 gauge 2-3/4″ shell (cylinder bore). 18″ barrels. An American classic in a rare compact package. Very well balanced, surprisingly accurate with .22 shorts. 6.75 pounds. Purchased used at a pawn shop in Green Cove Springs.

Ruger anniversary edition 10/22, .22LR, 16″ barrel. This isn’t modified, it came from the factory this way. It is a take down model with the short threaded barrel.  The only thing I added was fiber optic sights. I have owned a number of 10/22s in the last 30 years, I had more fun from simple ones than modified target guns. 5.25 pounds. Purchased at Jacksonville gun store.

Note, all the firearms above were made in America. Contrary to media myth each purchase required a full background check (which the buyer pays for) Lying on the form will get you arrested, likely before you leave the parking lot. Felon’s can not buy guns in Florida again. The media wants to portray my state as lawless to fit their narrative, even if it has nothing to do with reality.

The Ruger Mini-14 is in .300 Blackout, it is on loan from a friend. It is much better than the one I owned in the 1980s. Even using 220 grain subsonic ammo it is still loud without a can on it.

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Chris Pryce visit

Builders,

Over many years, builders have followed the exploits of 3,000cc Corvair / KR-2S builder Chris Pryce. He was just at Corvair College #39 in Barnwell, where he was PF Beck’s 300th passenger in his Corvair powered Pietenpol, but Chris’s involvement with Corvairs goes much further back.

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Chris got his Private Pilot license at age 18, just before he enlisted in the USAF. We met in person at Sun n Fun nearly 10 years ago,  where he explained his passion for experimental aircraft goes way back, as his father, a global commercial pilot, first started planning on a homebuilt about the time Chris was born. In spite of deployments, starting a family, becoming an officer, and a KC-10 tanker pilot, Chris has still made a lot of progress on his KR. He ran his Corvair at Barnwell college 18 months ago, and his airframe is now nearing completion.  It has all been a lot of hard work and well earned achievements in a life of a young American we can all be proud of.

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While on TDY in Florida, Chris rented a Cessna 152 and flew over to our little airport for a visit. I was glad to invite him as a small thank you for his returning work at the Barnwell College as a volunteer assistant. We had some fun around the airpark, went to dinner on the water in St. Augustine, and Chris got a chance to fly some hardware from a time before the USAF even existed.

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An officer in the USAF, flying 600,000 pound aircraft around the globe, but he still has a sense of humor. Here Chris at my backyard range brings the concept of the Captain Morgan photo op (“Captain Morgan” Contest at #39) to a new setting.

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Above, short 15 second film of .410 pistol in action.

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Above blast from the past, Chris at CC#24, Barnwell with Kevin and Shelley. You can see a film of Chris’s engine running three years later at Barnwell at this link: https://youtu.be/xDfX78pa6ug

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Above blast from the past #2, with Chris at CC #20. There is a very funny inside story about Chris flying a light plane this day, his first time in the cockpit in a number of years. He stayed to the very last hour of the College before driving home 1,000 miles to the Florida Panhandle. He drove the furthest distance to the College.

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Above blast from the past #3, Chris and I at Sun n Fun 2009. What kind of a guy buys a Corvair manual while wearing a VW shirt?  Evidently one with a great future ahead of him.

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Above, back to 2017: On left Pat Amble, on left, production manager at SPA/Panther got to meet Chris at CC #39. When Chris showed up at our airport, Pat took him out for a several hour flight in the family 1942 Stearman. Pat’s father is a Vietnam era USAF vet. and liked the idea of sharing the experience with a current USAF airman.

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A week after Chris left, a got a short letter in the mail, It was from Chris’s father on the west coast (Jerry Pryce was at CC #38 in Cloverdale CA in 2016, he is building a 3,000cc Corvair / Sonex. Dad is also a DC-10 pilot, a nice connection. ). It shared a few words of thanks for things we have done with his son. I sat at my kitchen table and read the note a few times.  While I think of Chris as a friend, truth be told I am a lot closer in age to his dad.  Holding that piece of paper in my hands, it was very easy to understand how immensely proud Jerry must be of his son’s efforts and achievements. It was one of the very few times in my life where I wished I had children of my own.

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‘Rule of thumb’…. part #2

Builders.

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As a follow on to: Rule of thumb in evaluating gear mesh , I present part #2

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Question: Why does it say “Wear safety goggles” when it really should say “Do not put thumb on top of chisel when striking with hammer’?

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If you needed engine building advice, would you ask a man who just had a manicure, or the man who has a bloody thumb?

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Compression and Detonation Testing, #1

Builders,

I am going to cover this test project in a short series of articles. Below are some photos of the test hardware we will be using.

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As the title implies, we are going to run two separate tests, and share the data. I am going to put the results on You Tube also, because I want builders to see the results in action.

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The Compression test will be done first, it is fairly straight forward. I am building the engine, giving it a break in run, and then checking the differential compression, and running a base line full power run and noting the full RPM the engine makes.

I am equipping one head on the engine with small threaded ports next to spark plugs. For the base line run, these will be sealed. For the second test, I am going to open them up so the engine differential compression tests near zero 0/80) on those cylinders, and run the engine again and check the full RPM in comparison to the base line.

There is a widely held, but mistaken belief, even among aircraft owners and mechanics, that a cylinder with a differential compression of 40/80 makes half power, and one with 0/80 makes none. Neither of these are remotely true. The differential compression just measures flow against a known orifice, and does not correlate to any percentage of power out put. If the myth were true, the test engine with the three ports open would make less than 50% power output, but as we will see, it will do far better than that.  From professional dyno testing done by Dan Weseman and myself last year, we will be able to put HP numbers on the test stand RPM outputs, and the comparison will be enlightening to many people.

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The second part of the test is to show how rapidly, and how much power is lost when an engine is detonating.  Again, I will establish a normal running base line for the engine, and run it at full power for one minute at that setting.  This will be immediately followed by intentionally over advancing the timing to make the engine detonate. Several things I want people to see:

The engine will actually appear to run better at idle.

It will not detonate at modest power output.

When the throttle is advanced to full power, it will run normally for a few seconds, and when it reaches ‘kindling temperature’ it will suddenly begin to loose power.  This power loss will be far in excess of the engine running with 3 cylinders with zero differential compression.

If the throttle is not retarded, the power will continue to drop, to well below the level required for flight.

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We are working to get the engine instrumented with recording CHT’s and EGT’s for the detonation tests.  These will show a very sudden spike in CHT’s and a decrease in EGT’s, as all the BTU’s in the engine are destructively going into the heads. I will be working to capture this on video, so everyone can study the effect, know it when they feel it in their plane, and abort their test or take off. Again, a person with a correctly built engine and set timing will not experience detonation, but over the years, I have had a shockingly high percentage of people refuse to set their timing with a light, and I have people who never took advantage of my 39 free colleges to learn it directly from me.

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The last part of the tests will be a disassembly of the engine, after it has been detonated to the point where it would no longer make enough power to sustain flight, to show the internal damage done.  Because we teach people to use forged pistons in Corvair motors, and because the head studs in the engine are 9″ long instead of 1″ like a Lycoming or Continental, the visual results will be different.  I will carefully document the changes on the engine as a reference for people inspecting engines.

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The engine in the tests will not have a fifth bearing, nor will it have new seats and guides, and afterword, I will salvage some items like the prop hub and starter, but these test will still be expensive, costing several thousand dollars and perhaps two weeks of labor.  I am conducting them so builders will have a chance to learn something. It this happens the time and the money will have been well worth it.

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Test engine, 2,700cc’s. This bottom end came out of one of the two core motors we found. The plastic orange plug set is a kit sold by SPA/Panther specifically for Corvair storage and painting. Note, old style bell housing cover in place of 5th bearing.  This engine isn’t going flying, and the tests are all taking place in the combustion chambers.

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Heads getting reworked at SPA/Panther in advance of the tests. Travis Young (aka “Retro Black”) took care of the machining operations.  Their machine shop is set up for both engine and airframe parts production. The heads are getting perfect head gasket machined surfaces, and welded on intakes, but the valve job and the guides are just street car level work. Again, the motor will run for less than one hour, it doesn’t need new guides.

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Engine getting decked in the mill. These surfaces are now perfectly true and flat. After severe detonation, warping in the heads can often be measured directly with a straight edge. The head gasket areas are often impressed into the heads, and the lower row of studs can become misaligned. Detonation puts a tremendous amount of heat into the heads, enough that they will plastically deform.  Most people think of detonation putting holes in pistons, but it only does that on cast pistons. On forged Corvair pistons, the damage is more subtle, the oil control rings become stuck in the grooves. I intentionally specified forged pistons because the engine will actually tolerate a lot of abuse with them. They are a margin  of safety on small mistakes, but they will not provide immunity for fools.

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Head bolted to a fixture plate in the Mill. The unit is a very nice Chevalier with DRO. It is in good shape, having lived in a tool room most of it’s service life. Next time you See Dan at a College or an Airshow, you can get him to share the story of how he bought this piece of equipment for $6.

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“It ran great when we parked it”

Builders,

Vern and I picked up two core motors on Saturday. Vern knew the owner very well, and he had them both for more than 25 years, stored inside, in a dry place, but not sealed. Vern even knew the Corvair collector, another friend who sold these engines to the man we brought them from. Below are some pictures to illustrate why you should carefully store your engine following the advice I wrote in this story: Storing a completed engine.

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Upon inspection, each engine had 2 cylinders which were clogged with corrosion. Why? because on a Corvair, one exhaust valve on each side of the engine is always open. If the exhaust isn’t sealed, or the engine isn’t in a bag, over a long period of time, those cylinders will rot. This is why I have always said to bring a 3/4″ wrench and turn the engine 360 degrees to make sure it doesn’t look like this inside. These motors didn’t rotate at all, although they were probably perfectly fine when pulled from a car thirty years ago.

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Above, “Weird scenes inside the gold mine” . Think about how many times someone has told you the BS that lead in fuel is “good for valves” as if  it was the 11th commandment.  I have said this a zillion times: “The byproducts of combustion of leaded gas are highly corrosive in the presence of any moisture.” Leave it for a week , or a month, fine, but not longer. This is why we use unleaded fuel to break in motors at colleges, because they will be stored before use.This engine probably did run great the day it was pulled from a car. But with the exhaust left open, it formed this corrosion in two cylinders. The engine was filled with lead, so I am guessing the last time this engine ran in a car was in the mid 1970s. Historical note: I have been working on engines for decades, but I have never seen a Valley Forge brand spark plug. Maybe the specialized in the cold end of the heat range.

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Judging a book by it’s cover story: When we got the engines back to my hangar, I knew they were going to need a fair amount to work, so I broke out the pressure washer and the 375,000 BTU steam generator. Combined with a generous dose of purple cleaner, the engines looked very good on the outside in a few minutes. When engine shopping don’t care if the engine is clean, only if it rotates. Counterintuitive Grease Monkey Experience: an engine that is covered in goo on the outside constantly leaked oil, and thus had a continuous oil change going on. This motor invariably looks better inside than one which drove the last 3 or 4 years without an oil change. Besides, an oil leak core motor began the “self cocooning” anti-exterior corrosion process before hibernating a few decades waiting for you to need a flight engine core.

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Above, another hint at how long this motor was stored: When was the last time Shell sold spark plugs?  Look at the size of chemistry project going on in Cylinder #2. Part of what drives this process is the fact Corvairs have aluminum heads and iron barrels, diving a dissimilar metals factor an all iron car engine would not have.

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