Rain, Snakes, and Power Testing

Builders:

In between thunderstorms today, Dan Weseman suggested we do some test runs and compare the static rpm output with 3 different props on two Corvairs, the 3,000 cc engine on his Panther (Why Not the Panther engine?) and his 3.3 liter engine on my run stand. (SPA / Weseman 3.3 Liter Corvair now running). The idea was to run both engines with three different props in rapid succession and compare the peak static rpm’s with a very accurate optical tach. The work went pretty quick because we also had Corvair/Panther builder Paul Salter on hand. It took about 90 minutes, but this was broken up by several thunderstorms that drove us back in the hangar.

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Summer is the wet season in Florida, and although these numbers may seem astronomical to Californians, We had 5″ of rain here today, bringing the week’s total to 16″, and the remains of Hurricane Erica have not even arrived yet. We are on high alert for any more rain because we are now at the flood stage.

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Above, a 2013 photo of our yard, illustrating “Flood stage.” Read the story : Let It Not Rain.

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Flood waters bring out Snakes looking for higher ground. At our airport that means water moccasins. Dan went over to Uncle Bob’s hangar to retrieve the prop tach. Bob wasn’t home and walking up to Bobs shop door Dan saw a giant water moccasin hiding right next to the entrance. He called me on his cell with the short message “I am at Bob’s, bring a gun, now.” 1 minute later I arrive on the dirt bike with a 20 gauge. A single shot dispatches him instantly. Oddly, he doesn’t have the typical behavior (snakes without heads still squirm and strike for 20 minutes) Measured he is 44″ long, very large for a Moccasin, potentially deadly to a human. They have very heavy bodies, when I pick him up he weighs as much as a starter motor.

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Above, In 2013, Vern stands by our pond with a 42″ moccasin. This was the same week he stepped on one in my hangar. read the story: Fun with Agkistrodon Piscivorus and Vern’s Aero-Trike.

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Testing went smoothly. For a good comparison we made sure the full power ignition advance as set on both engines to exactly 30 degrees. They were both fueled with 100LL. Both my stand and Dan’s plane have MA3-SPA carbs, and we verified on EGTs that at full power both engines had the same peak EGT (1300F- That is the effect of the carb going slightly rich at wide open throttle, as desired.)

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One of the props we used in the Comparison was the same 2 blade warp drive that I run on every engine on my test stand. It is 60″ in diameter and pitched low. It isn’t meant to replicate a flying condition, it is sized and set to optimize it as a break in prop. Over the last 12 years I have run more than 300 engines with it, so it is an excellent comparative tool. Today the 3.3 engine cranked out a record 3400 rpm with it. This is a full 100 rpm over what a 3,000 cc engine will do.  At lower rpms with Sensenich props, the difference was even greater. This is a power difference that you can feel with the seat of your pants in a plane. While most people understand bigger motor = more power, there was actually a guy at Oshkosh who saw Dan’s larger engine on display and felt obligated to say that the larger engine would make less power because of some reason that made sense only to him. Another case of reality getting in the way of a pet theory. Paul Collected all the data, and Dan will write it up on his website later, but it was a good comparison on the flight props also.

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Snake Postscript: Bob comes home later and tells us why the giant moccasin ‘died instantly”…..Bob had already shot him point blank with a .22……….Bob also said that oddly, the snake hardly moved either, but he was on his way to Church and he just left him were he has laying by the shop door, where Dan later saw him……..and later our neighbor Richard asked what the shot was, and when I was about to tell him he mentioned the night before using his dodge 2500 to run over a “four foot” Moccasin that was crossing the road “down by Bob’s pond”……Evidently we had through combined effort killed the same snake three times over.

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Corvair College #35, now full, sign up closed

Builders:

Corvair College #35 at Barnwell SC in November is now full. The sign up has been closed.  For people who missed this, a friendly reminder that This is the 6th consecutive College we have had on the same weekend at the same location. I published the dates 10 months ago, and the sign up went active before Oshkosh. I have reminded readers about the sign up in many stories that appeared here. We do our best to let everyone know in advance.

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If you are signed up, you will begin receiving emails about the college shortly. If you are new to colleges, please read them carefully, they have a lot of detailed information.

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Above, a picture from Corvair College #31 at Barnwell last year. Tim Hansen sent in this  photo he entitled “Chuck Callahan is a Good Sport about helping with my engine  until 2:30 a.m.”  Yes, builders do work every late at Colleges, particularly Barnwell events. No one is required to work until the middle of the night, but many people do, and there is also the crowd that gets to see each other only once or twice a year that stays up late socializing. The events are productive and fun.

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-ww.

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Running your engine “Over-square”?

Builders:

There is a long standing piece of “hangar wisdom” That says you should never fly a plane “Over-square” . This condition is defined has having a higher manifold pressure in inches of Hg than you have RPM in  hundreds. Example: 25″ map and 2400 rpm is said to be “over-square”, where as the reverse, 24″ map at 2500 rpm is said to be “under-square”. This rule is brought up primarily to warn pilots about putting the engine in a condition where it might be prone to detonation.

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Like many things said in hangar stories, there is some element of original truth in this, but it doesn’t apply to all engines nor conditions. In the end it was supposed to be a little memory device for those unwilling to understand the larger principle.

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The origins of the statement are of attributed to being a good way to run Lycomings, or more particularly Lycomings with constant speed props. Over time, the “over-square” rule became something that people tried to apply to any engine in any situation. But a basic look at a trip around the pattern shows that the rule doesn’t work, not even in Lycomings; If you are near sea level and begin your take off roll at wide open throttle, your map will be darn near the outside air pressure, very close to 29.92″ on a standard day. Since no direct drive Lycoming with a fixed pitch prop turns 2990 rpm static, every take off is “Over square.” Even Constant speed equipped planes have redlines between 2700 and 2800 rpm, and thus would still be “over-square on take off.

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So what protecting these over-square planes from detonation on takeoff? Something very simple. Aircraft carbs, by design, run rich at wide open throttle. In private pilot school many people were told this was for “Fuel Cooling” the air-cooled engines, but that isn’t what is going on. The mixture running rich at wide open throttle effectively increases the comparative octane of the fuel. When you look at Octane ratings of old fuels like 80/87 or 100/130 or 115/145, these dual ratings reflect the comparative detonation resistance both lean and rich.  regardless of it’s name, any fuel will have more detonation resistance when the mixture is rich, and aircraft carbs set properly do this for you.

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Lycomings and continentals are configured this way, and if you have a properly set Stromberg or Marvel carb on your Corvair, it will do it also. However, you have to remember that it is always preferable to run the carb wide open when it is heavily loaded, ie, “Over-square”. Never let anyone talk you into backing off the throttle slightly on climb out, it is a very poor practice.

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The way to make sure your carb is set correctly is to tie the tail of the plane to something solid (not just chocks) and run the engine up to full static rpm. Give the engine a few seconds to stabilize, and then just barely pull the mixture out slightly. If it is set correctly, the rpm will increase as you lean it out, because you are going from an anti-detonation air/fuel mixture of say 10:1 toward best power at 12:1.  The power goes up, so the rpm will climb slightly. This is a good condition. If your carb doesn’t do this, it isn’t set rich enough. You can also watch this on your EGT.

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Where the warning comes into play is avoiding running an engine over-square in cruise settings where the throttle is partial open, and there is no additional richness to suppress detonation. Many times people refer this condition as “Lugging” the engine.  With Corvairs, I consider it very important that the engine turn at least 2,700 rpm static with the prop pitch set for flight. This way, on every take off and climb out, The engine will be operating close to “square” which minimizes the chance of detonation, and additionally the engine has substantially better seat of the pants detectable performance with just 100 more rpm static.

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Some builders, particularly Pietenpol builders like bigger wood props that often yield low static rpms in the 2400-2550 rpm range. I feel that this is an undesirable condition because such a prop tends to “lug” the engine, not just restraining it’s performance, but it is prone to cruising in a condition of low rpm and higher manifold pressure, but without the carb being in the wide open throttle position. Many guys feel that flying around with a larger wood prop at lower rpm is easier on the engine, but I can make a pretty good case that just the reverse is true, especially if the builder ever runs car gas.

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More Rpm will not hurt the Corvair, keep in mind that it did more than 5,500 rpm in the car and was designed to cruise in the car over 3,000 rpm. Your aircraft engine is far better built than any stock Corvair Car engine from the factory, so more rpm will not hurt it, but loading it at lower rpm just might.

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-ww.

 

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Above, a new 2,850 running  on the test stand in our front yard. During the cam break in period, (20-30 minutes) We run the engine between 1800 and 2200 rpm. The throttle is only part of the way open to do this. During the later part of the break in runs we run the engine as high as 3,200 rpm. At that condition the MA3-spa carb on the run stand is wide open and the O2 sensors and the egt’s indicate the engine is in the anti-detonation rich zone. Read more at this link:  New 2850cc / 110hp Corvair in photos.

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Center, above Joe Foss (USMC-CMH) stands with Charles Lindbergh in the south Pacific in WWII. Lindbergh was a factory rep for Vought, and one of the things he taught pilots was how to get extremely good range by running their engines massively “Over-square”, (very low rpm, high blower and high prop pitch) It worked, but the training included elements of making sure the air/fuel was very rich. Foss went on to be the Governor of South Dakota, Commissioner of the AFL, host of “The American Sportsman” and president of NRA.

Thought for the Day: Attitudes are not Ideas

“Ideas that fit on bumper stickers are not ideas at all, they simply are attitudes. And attitudinizing is no substitute for analysis. Unfortunately, too often television is to news as bumper stickers are to philosophy, and this has a corrosive effect on public understanding of those issues on which national survival may depend.”

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-RMN, 1980

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The quote above is a very good explanation of the reason why rule #1 at Corvair Colleges is “no politics and no religion” on the discussion topics. I point out to builders that we have much to do, and a limited amount of hours at the College, so we can’t spare the time.  As a practice, I like people to discover what they have in common before they find out what divides them, but the real issue is related to the quote; most things people say on these topics are neither philosophy nor analysis, they are mostly attitudes and bumper sticker slogans, driven by declining quality of ‘news’ in this country, tied with the fact few people read books anymore. (Books written by tv news personalities are not a good substitute for reading original texts.)

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Here is your aviation connection: Too many people in aviation today rely on the stuff printed in magazines and hangar flying stories for their ‘education’ on important topics. The typical magazine story on flying is bumper sticker compared with a book like this: Greatest Book on Flying Ever Written, (Is your life worth $16?).

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You can be mad at the media if you like, but they are just responding to the ever shorter average attention span. Several years ago, the word went out among aviation writers that we were to limit every story to 1,500 words or less, no matter what the topic. It wasn’t a print space vs ad space issue, because the request applied to on-line writing also.  When questioned, editors were able to produce convincing evidence that most people just skimmed articles, and 90% never read anything longer than 1,200 words. There was proof that people, even ones engaged in something serious like aviation, really preferred bumper stickers. For the 10% or so that got into aviation to find out how much they could learn by reading and learning and building, I offer a different path: Thought for the Day: Mastery or?. If you are an individual, it doesn’t matter what the majority are doing, it is only important to find a path that suits you.

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Above, a 2009 photo. I stand between Bob Burbank, 20,000 flight CFIG on the left, and on the right is my instructor and mentor is flying, the legendary Chuck Nelson. Chuck has been flying for 65 years. He bought his first plane, a ’38 Cub, when he was 15.  . His background includes flying in the U.S. Air Force, crop dusting, water bombing, weather modification, racing at Reno, and working with both Duane Cole and Curtis Pitts. He became an instructor in the USAF in the early 1950s, and it emerged as the calling of his life. A long list of former students covers people working in every branch of the military, most major airlines, a U.S. aerobatic champion, and a guy who builds Corvairs for a living.

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To qualify as an idea, it must require thought to consider. Any statement or slogan that just stirs an emotional response isn’t being presented as an idea. Slogans stir up the converted, but only ideas breed understanding.

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You will often see writers using the excuse of safety to write things that are designed to alarm people. On serious subjects, there is no valid excuse to resort to alarming people. There is a big difference between making people Alert to something opposed to making them Afraid of it. The first asks that they think about it, and the second is designed to produce a knee-jerk emotional reaction. In my book that is a form of conditioning people to get them to react in a desired way without thinking. It isn’t a positive view of individuals.  I like people who are passionate about flying, but this doesn’t extend to people who default to being emotional about it because they were unwilling to read about and consider the concepts that aviation is built on.

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Some people who know the quote above, get distracted by the source. To me, it isn’t an issue. In my experience, not all smart men are good, and many good men succumb to doing things which are not smart. In either case, it provides food for thought. The quote above is from Richard M. Nixon’s memoirs.

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-ww.

Colleges #34 and #35 updates; a Plan for Progress

Builders:

We are getting in high gear for the upcoming College #34. If you are one of the 70 builders signed up, we will shortly be sending out the detailed instructions to your email on getting the most out of the College. If you have been to a college before, they will be familiar, with a few new details. If this is your first college, please take the time to read them in detail, it will make a large difference in what you will learn and accomplish.

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If you are thinking about heading to CC#35 at Barnwell, you are down to the wire on the sign up. There are just a few seats left. Sign up is here: Corvair College #35, Barnwell SC, only 20 seats left . (the title is from a week ago, there are just a few seats now.) If you would like a visual look at what a Barnwell College looks like, check out this video that the EAA made: New EAA video on Corvair College#27, Barnwell 2013.

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This week has been very busy with College prep. The day before we leave is busy, but the peak pressure is actually about 10-14 days out, because there are several deadlines like tomorrow being the last day we can get things into the powder coater. There are similar deadlines for each of our machine shops. Besides this, the phone has rung off the hook and we have had a good backlog of email to deal with. If you have called but had an issue getting the machine, it is because I am on the other line. If you need to contact us, send an email with your phone number and the latest hour I can call you back. In a few days I will be able to cover these, we generally try to call every person headed to the college to touch base before we leave. As Grace is out of town this week taking care of her parents, we are trying to coordinate contacts over email and the phone, please be patient, we will gladly cover your questions.

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A Few words about sticking to your own “Plan for Progress”:

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Above, a photo from CC#30 in Mexico one year ago. On the right, Dick Navratil…… I glanced at the EAA video mentioned above to make sure the link worked. If you look at the 1:10 mark on it, you will see a short interview with Dick……If you didn’t know him, and didn’t immediately make the connection, he is the man in this story I wrote from June: Dick Navratil Passes from this earth, June 4th, 2015.

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I knew Dick a long time, and I would like to say I am sorry at his passing, but anyone who knew him can tell you he got nearly everything a man could out of homebuilding. He was 66, and that is not long enough. We don’t have ultimate control over how long we have, but Dick’s life remains a lesson that you do control how much you get out of every week, and what your attitude is about events. To Dick, life was a challenge and an adventure to be shared with friends. He built and flew seven or eight home builts, had countless hours aloft, and friends near and far. He started every new flying season in his life with a Plan for Progress.

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This last week saw a public shift in some of my suggestions for sources, and a little bit of the drama club stuff as a reaction to this change. The new sources will allow builders to fine tune their own Plan for Progress, and part of it is geared to give me more hours in the shop, to work with builders. These are good things, but there are people stuck on internet debates and entertainment which should have no effect on their plan, but it does.

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There were things in homebuilding that Dick cared about greatly. When he no longer felt up for publicly advocating them, he often spoke to me and asked that I keep themes he cared about in the forefront of discussions, particularly in the world of Pietenpols. But none of that ever stopped Dick from making progress on all the planes he finished and flew. He was neither optimistic nor pessimistic, he was simply determined. This is a perspective worthy of emulation.

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In the next few weeks over 160 builders will head to a Corvair College. The will learn and make progress meet friends, have an outstanding experience. Others at home will make solid progress, getting closer to running and flying one day at a time. But there will also be another group who get distracted from keeping their own plan for progress. These people don’t have much positive inertia on their project because they stop and wait to see how every promised distraction turns out. They feel like they are planning but if Dick were here to say it, he would tell them they are only waiting and wasting time, hours that none of us have a guarantee on. Dicks success in homebuilding came from planning and progress, and not being dissuaded. If you will or will not complete and fly your plane is primarily determined by your decision tonight: will you make a plan and progress or will you wait and see?

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-ww.

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Many people want to believe that some new product in aviation will arrive and ‘revolutionize’ everything. I think the root of this fantasy is that they would like the work and learning to be removed and save them the effort required to stand in front of a machine and say “I built this plane.” I have been in aviation for 25 years, I have seen 25 seasons of ‘revolutionary!’ things come and go with little or no affect on accessibility to flight for working Americans.

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I have watched many of the same people get taken in by a new ‘revolutionary!’ idea every few years, never seeing that they would have been long flying if they had just given up on ‘new revolutionary!’ products with lottery ticket odds of success, and instead embraced the philosophy of proven designs with a track record in place of a promise. They will be waiting there in another 10 years because that bus isn’t ever going to come. The rainbow bus line from Unicorntown doesn’t have a stop on reality street, it only is headed to cyberville, and there is no airport in cyberville.

Read the whole story here: Waiting for the bus from Unicorntown to Cyberville

Compression Ratios, Fuels and Power Output

Builders:

Here are three topics that are related. Although the conversion manual covers this in some detail, I will put a short summary here.

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We have 3 popular displacement s for Corvairs 2700, 2850 and 3000 cc (read more: Sources: Choosing a displacement.)  The latter two are made with a very special dish in the piston to lower the static compression, but keep the ‘quench area tight. On any of these displacements you can either put lower compression 95 hp heads, or you can put higher compression 110 hp heads. Right there you have six combinations with different compression ratios, but it is also possible to build engine with high or lower compression, but those six are the popular ones, and having the option allows Corvairs to suit different builders purposes.

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The two basic rules are: The higher the compression, the more power the engine will make….and There is a limit to how much compression you can use with car gas. The commentary here is general, but it comes running engines on our own planes from 7.7:1 compression (1998 2700 engine in our Pietenpol) to 11:1 compression (2005 3100 engine in our 601XL) I write this as a guideline, if you have a specific application, feel free to ask in the comments section.

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Basically any of the three displacements with 95 hp heads will have compression ratios from 8:1 to 8.5:1. Engines built with 110 hp heads will have ratios from 9.0:1 to 9.5:1. The variation is mostly in the machining done to the head gasket area, and the actual gasket thickness.

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The First question is what is the lowest Octane fuel you will ever use in your plane? In the answer is “I will never put anything but 100LL avgas in my plane” then you can use any compression ratio you like up to 11:1. Your engine will make about 5% more power for each whole point you raise the compression. But….you can never, not once, ever, run the engine on car gas, even 93 octane car gas if the compression is much over 9.5:1. 100LL is great fuel. yes engine can be detonated on it, but this is done by leaning the motor out far too much or not having the timing set correctly. Our 11:1 compression engine flew more than 600 hours on two different airframes The first 200hr was 11:1, we dropped it slightly to 10.5:1 for the rest of its time) It never detonated at all, and it never saw a drop of car gas either. 100LL when running slightly rich has a comparative octane of nearly 120.  Keep in mind that many people swear they will use nothing else, but later after the 40 hrs. are flown off, some people start getting cheap, and the are tempted to run car gas in a 9.5:1. They might get away with it under some conditions, but sooner or later, they will pay.

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Let’s say you are going to run ethanol free 93, or some mixture of this and 100LL, how high is smart to go? You could run up to 9.3:1 and get away with it, as long as you don’t excessively lean it. But what is the benefit of running on the ragged edge? If your engine is built with a ratio of 9.0:1, there will be hardly any measurable performance difference, but it will have a large increase in resistance to detonation.

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What about running 91 or 92 Octane car gas? Then it seems prudent to shoot for the lower range offered by using 95 hp heads. I have never been interested in speculation on what “should work”, I am much more interested in builders developing enough judgment to understand they are far better off with set ups that have a greater margin of safety than a slight performance edge.

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Examples:

Woody Harris , who’s plane is pictured below, started flying with a 9:5 to 1 compression 2700. (Flat top pistons and 110 hp heads). Because he was planning on switching to a Turbocharged installation, he went to an 8.25:1 2,850. (dished pistons and 95 heads). Woody had enough fun flying around, that he didn’t get to turbocharging. Woody has long reported that the power output between the high compression 2700 was about the same as the low compression 2850. This isn’t a surprise. Woody mostly flies on 100LL, but if he or anyone else was planning on running 91-92 octane fuel, they would be vastly better off with the lower compression 2850.

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My own 3,000 cc engine: Is set up at 8.3:1 compression (dished pistons and 95 heads) Although it might make 6 to 8 more hp if the compression was raised to 9.5:1, I don’t care because I am not running 100LL, my choice is to run ethanol free boat gas, which here in Florida is 90 octane and sells for about 10 cents a gallon more than 93 with ethanol. This week that is $2.80 a gallon. This is a very clean burning fuel and  it stores for a long time. On a cross country the engine will not care if it drinks some 100LL, again the compression ratio is determined by the lowest octane you will use, not the highest.  A few more hp isn’t going to make the Wagabond into a speed demon, I am after absolute long term reliability and being able to run any fuel available.

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Ron Lendon’s 2,850: Ron built a clone of Woody’s 2,850 engine with dished pistons and 95 hp heads. Recently he changed to flat top pistons and 110hp heads. This changed his compression ratio from 8:1 to 9.5:1. Yes, this will make more power, and it is OK because Ron says that he only runs 100LL . In short, he didn’t start with the highest performance option for the fuel is was going to use. Ron has worked for GM in their enginnering department for decades, so perhaps like most people who saw fuel prices in 2009, he might have been thinking about auto fuel then. But it pays to plan around the fuel you will eventually use. To keep things in perspective, I am sure that a 601 with a low compression engine and wheel pants met a 601 with high compression and no pants, the one with wheel pants might be faster.

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In the above photo, Woody Harris’ 2,850cc Zenith 601B sits at the end of the ramp in North Carolina at First Flight Airport with the Wright Brothers Monument in the background. Woody’s home airport is in California. He has nearly 500 hours on the plane without issues. read more:Woody’s 2,850cc Corvair/601XL hits 400 hours.

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Woody in the Grand Teton National Park WY

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Lest anyone think that low compression engines don’t make good power, above, Woody flying over Grand Teton. He often flies around the Sierras, and has flown to the highest and lowest airport in California in the same day.

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Above, a drop forged, made in the USA piston for the Corvair. The  displacement of this piston is 2,850 cc. read more: Turbocharging Corvair Flight engines Pt. #2

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2005 photo of our 601XL in front of our Edgewater hangar. The engine is a 3100 cc with 140 hp heads, oversized exhaust and 11:1 compression. Because it was a tail wheel and low drag it was fast. With wheel pants and the right prop turning 3,500 rpm, this plane could exceed 145 mph at sea level. People asked about weight, but at the 601’s low wing loading, it is slightly faster when loaded. They are good planes, but other than demonstration purposes, anyone really concerned about getting the last mph out of a 601 probably picked the wrong plane. It beauty is in utility, not speed. Note the size of the inlets: Here we have the most powerful Corvair engine that builders have heard of, yet it cooled itself just fine in hot Florida with 4.75″ inlets and a front alternator. It is a myth that this installation needs giant inlets to cool itself.

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Same plane, at sun n fun 2006. Sensenich prop was faster, but didn’t climb as well. I could have built the same engine for the plane we have today, but instead I chose something on the other end of the compression scale because I don’t wish to be tied to 100LL forever. Take your pick, what ever makes sense to you.

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Above, Dr. Andy Elliott, of Mesa AZ with the same engine on his 601XL. The photo was taken at Oshkosh, so it is safe to say the plane flew without issue. Andy flew the engine another 400 hours. His state has the highest summer temps of anywhere in the US, and yet the high performance engine cooled through the same size inlets. Andy’s plane could do nearly 140 mph. The power was a factor, but aerodynamics matter more and are cheaper. Before selling the engine to Andy, I reduced the compression slightly, but he still knew to always run 100LL.

-ww.

An Internet drama in a teapot.

Builders:

A little internet drama is a guilty pleasure of many aircraft builders. Submitted for your approval, a little drama that ran this week; It has a cast, a plot and a twist. Fun, but in the end it is only drama, and like a dozen other dramas before, it entertains, but doesn’t advance your plane toward flying.

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Cast:

Mark from Falcon Heads, Roy from Roy’s Garage, and 601XL builder/pilot Ron Lendon.

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Background:

At the end of last year, I privately told Mark and Roy that I was no longer going to have them at Corvair Colleges nor in my booth at Oshkosh. After nearly 10 years of being their single most vocal supporter, I was tired of Mark not making heads and Roy telling people his work was “Technically Correct” with the implication that people choosing other suppliers were making a mistake. To retain some portion of builders, they decided Mark would come up with a special set of magic head mods for $500, and Roy would run people’s engines on his dyno with promises of further power increases. To sell this to people, they enlisted Ron Lendon to put it on his plane, and then tell people what an improvement it was. The broke the ‘story’ on the “Corvaircraft” discussion group, a venue where I am not allowed to participate.

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It all sounded pretty good to people who like a good drama/conspiracy theory. Mark and Roy had “discovered” the dirty secret of Corvairs: The way we tell people to build them (Just as Mark and Roy have done for years) is terribly down on power. They claimed to have raised Ron’s power output by something like 24%. Ron followed up with a detailed flight report that showed his plane to now run 116-117 mph, a large improvement. Roy then comes in with some graphs showing Ron’s plane now makes 100 HP.

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Sounds great, except:

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Several well known and trusted 601XL pilots with 2700 cc Corvairs chime in to say that their planes are that fast already. Lynn Dingfelder and Phil Maxson, who have both been flying for years, point out that their planes do 115 mph, and Ken Pavlou’s will break 120, in the same configuration as Ron Lendon’s in spite of Ron’s engine being a 2,850 cc. The logical observation is that these unmodified airplanes have the same output as Ron’s now does, which Roy’s dyno said to make 100HP. Most people concluded that the test validated my long standing power output claims, because there is little variation in 601XL airframes, so the same speed  = the same power.

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Points to understand:

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Roy claimed to have previously tested a 2700 cc engine and the output was only 82-83HP. His contention was that all 2700s built to my suggestions had that power output. Clearly that wasn’t so, based on the other pilots reports compared to Ron’s ‘modified’ 2850.

I have little doubt that Ron’s plane had an improvement. He had been plagued by engine problems in his first years of operation, mostly caused by his adamant use of a obscure carb of a 65HP engine. In spite of working for GM for decades and having significant flying time, Ron  missed that his engine was running lean enough to damage itself bad enough to need a rebuild. His plane was never a particularly good performer by 601 standards. He got another Carb, much closer to correct, but still didn’t recognize it was running lean.

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There was no ‘before’ run made on Ron’s engine, just an after. Although he mentioned that his plane now has flat top pistons, he didn’t mention that the heads were changes from 95 to 110 high compression ones,  the valve size increased, and again the carb was made richer. because it was never tested, there is no before and after, but judging from performance, his plane does run much better, but evidently not significantly better than other 2700cc 601XL’s. Changing the compression from 8;1 to 9.5:1 and making the carb a lot richer could account for the improvement alone. Perhaps the other ‘modifications’ have negligible or negative effect.

A great claim was made that Roy’s dyno was scientific because it used a data program called “Labview”. A guy who got it from his work traded it to Roy for a discount. Same guy claimed “This is basically the same software & hardware that is used on a $50-$100K dyno.” I tend to disagree because you can go on National Instruments website and see they sell the Labview dyno soft ware brand new for $1,290. I don’t think having  that software makes Roy’s dyno the equal tool as a $100,000 dyno.

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No mention was made of correcting the dyno runs to standard atmosphere. Without this, there is no comparisons between engines, even ones run a few hours apart, far less weeks or months apart.

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Above, Roy and I running an engine I built in 2014 on his dyno. Several people chimed in on Corvaircraft to praise Roy for his testing, even though they have no experience with dynos. Does this look like a $100,000 piece of equipment? On the day in the photo we could not get a test more than a few seconds long, and Roy had to manually manipulate the controls, there was no real data from this. I am sure it is better now, but this isn’t the “technically Correct” infallible tool that some people suspect.  If you would like to read a dozen stories of practical testing spanning 10 years, look here: Testing and Data Collection reference page

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Above, a 2008 dyno calibration run in my yard in Florida. Notice Kevin and I are wearing jackets. We’re waiting just before sunset for a rare weather phenomena to occur: a perfect standard day of 59F 50% relative humidity and a pressure of 29.92. Any time you read a dyno report and it says “corrected horsepower,” they’re making a calculation, sometimes accurate and sometimes not, to adjust for their test conditions not being at standard atmosphere. Because we live in Florida near sea level, there have actually been three occasions the past years when these conditions were met during daylight hours on testing days.

Our dyno relied on the super accurate optical Prop Tach for the rpm measurement and it will only reliably pick this up in daylight. A few minutes after the photo above was taken, we made a dyno run which required no correction. By testing the same engine later in the week, we reconfirmed our correction factors for this particular dynomometer and we retained accurate measurements all year round. If you want to read the whole story, it is here: Dyno testing Corvairs, 2008 Any dyno run that doesn’t reference a correction to the ‘ICAO Standard Atmosphere’ has no meaning, and there is a significant difference between  the reliability of a calculated correction and a measured one, as we are doing above. People get excited hearing about ‘software packages’ but in reality the value of the tests relies on basic things like atmospheric corrections. 

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Above, Ron Lendon, running his engine on my stand at Corvair College #17, having a good moment. Yesterday he said this on Corvaircraft: ” I even heard WW say to Dan W. that he would fly the engine I just built at CC17 to the Bahamas. But I don’t here him saying that now, no he is heaping his opinion on people he called friends because they are behaving as he did several years ago. “  A big part of why Ron’s engine ran great on my stand is that my stand has the recommended carb, a MA-3SPA. He promptly went home and bolted the incorrect carb on his plane, because it was cheap, starting a long series of issues. Oddly, the people Ron is championing today, Ron and Mark, supplied him with parts and service that he was previously angry about. As for his evaluation of the behavior of ‘friends’, perhaps he can review the definition of “ingrate.”

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As for Mark or Roy being able to claim ignorance of the output of engines they happily built and sold to people, I submit the photo above: Marks EFI 2,700cc Corvair in 2007, on my dyno, right in front of mark’s shop in WI. He certainly didn’t think this motor, nor a carbureted one was 82hp that day. You can also see that Mark was present in the calibration story above. Roy had also flown as a passenger in Lynn Dingfelder’s 601XL and saw what a good running plane, with a stock 2700cc ww engine could do. Before making his claims this week he understood that his ‘modified’ engine in Ron’s plane was no more powerful than Lynns.

 My testing was absolutely satisfactory for Mark and Roy to sell heads and engines to people for years, but somehow they have suddenly ‘discovered’ that none of these engines worked, coinciding with them becoming unwelcome at events I am hosting. Think it over.

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That concludes todays entertainment programing. I am headed back out to the shop to prep for the next Corvair College, I suggest builders intrested in progress do the same.

-ww.