July 20, 2014 2 Comments
July 12, 2014 Leave a comment
In two weeks we will be headed back to Oshkosh. Once there we will be surrounded by hundreds of companies that will all attest on a stack of Bibles that they have carefully tested all of their products to protect the safety of their customers. In with these people will be at least 30 companies selling engines. Every single one of these companies will tell you without blinking an eye that their engine power output numbers are the result of careful Dynomometer testing. Almost all (90%) of these companies are lying about this.
Traditional dyno testing is expensive, and a bit of a production to adapt an aircraft engine to. To learn much, it requires hours of evaluation, and runs at different conditions. Any company that does this would be justified in taking a photo of this milestone in their company history…….except you can politely ask to see a photo of their engine on a dyno, and of course they will not be able to produce a single image of their engine running on a dyno. I actually had one company tell they had done 100 hours of testing, but had forgotten to take a single photo of it. In an era where nearly every human has a cell phone that is also a camera, please tell me who would believe this?
There are many kinds of dynos. Basically they all apply a load to the engine, and then measure the equal and opposite torque reaction resisting this load. No Dyno measures HP; they measure torque. HP is a calculation based on torque and RPM. If you building a plane, you don’t need to know this, but ideally everyone selling engines would, (but they don’t). A real motor head, like yours truly, knows this stuff. Combine this with some basic fabrication, and “Taa Daa!” the $500 dyno. Our dyno used the prop to generate the load, allowed the engine to rotate on it’s crank axis by using a front spindle from a Corvair car, and measure the torque with a hydraulic cylinder. Later we simplified it further with an electronic scale for measurement. Using a digital optical tach, the accuracy measuring HP was within 2%
I didn’t invent this kind of dyno, it has been around a long time, pictures of them in 1960s Sport Aviation magazines. This isn’t even the simplest kind of dyno. In one old Sport Aviation there is a picture of a Corvair hanging on a steel cable turning a prop, with a wooden arm touching a scale. Yes that works also. The pictures of our set up have been on our webpage for more than 10 years. It would be very easy for any company selling engines at Oshkosh to have built their own version. Easy, but not as easy as telling people they have hundred of hours of testing, but forgot to take any photos.
2003- Above, Oil system testing at Spruce Creek airport, 2003. We were testing how much pressure loss the cooler had when the oil in it was cold soaked for an hour at 32F. Testing like this is serious business. Note that Gus Warren liked Becks Dark, and I liked Michelob. Lot’s of companies like to have the appearance that they test products: they put people in lab coats and have them make scientific faces. I don’t care for appearances, I just want results, and the picture shows we drank beer while we let the oil cool off. I can put on a lab coat a lot faster than a salesman can become a motor head and teach builders anything valuable.
2004- Above, an O-200 on our dynamomemter; test crew from left to right, above: Gus Warren, Detroit Institute of Aeronautics, A&P 1990; Steve Upson, Northrop University, A&P 1976; yours truly, William Wynne, Embry-Riddle Aeronautical University, A&P 1991. While the way we dress may be slow to catch on in high fashion circles, we certainly know our stuff about all types of aircraft powerplants.
2008- Above, Kevin and I are standing on my front yard, wearing jackets. We were 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 was actually three occasions in four years when these conditions were met on testing days, and all our results we calibrated against these standards.
How you can build a Dyno for $500 if you know how they work and you can weld:
A page devoted to all kinds of testing:
July 11, 2014 Leave a comment
This webpage now has more than 550 stories, here is a sample of older stories that you may have missed. here is a reminder of 6 of them. If you would like to see a list if 200 of the stories in categories, click on this link: 200 Stories of aircraft building. Below, just click on the colored ling to read the story.
On flying planes: New Pietenpol, Gary Boothe, Cool, Calif.
Above, Gary’s Piet at its first public display.
“At first glance you might not see the inner motor head. Greg’s normal stomping ground is in international manufacturing, and I have never seen him without a collared shirt on, even when he was building his engine at Corvair College #24. But this is camouflage for a guy who has a long background of getting his hands dirty.”
On Installation components:
“If I were to pick a single topic that new builders are interested in, but know little about the applications of, It would be Fuel Injection. This is a topic dominated by misconceptions and myths.”
“Although I have read the biographies of several hundred aviators in the past 25 years, I can say without hesitation that James Stockdale had the most impressive personal code of all.”
On Risk management:
” In almost every case, the unfortunate person at the center had been told, often previously warned more than once, but they chose to ignore the warnings or discount them for reasons that frequently seem hard to remember after the damage is done. It is not the lack of information, but the willful choice to ignore it that is at the root of trouble.“
“If a builder spends many hours talking about super special oils, and how they can fix everything in your life including your 401K, and later comes to a college but has no idea how to install a distributor and set timing, I am going to tease him about spending a lot of time thinking about synthetic oil, an answer in search of a valid question, when he needed to be reading about the fundamentals of his engine.”
“If you are reading this, and you are producing a plane with your own hands, then you are in the arena of flight. You will know it’s great challenges and rewards. You will struggle to make it right, to learn, to keep going when most others quit; You will feel fear, and overcome it before your first take off. The hours you spend aloft in your own creation will mark special days in your life long remembered when most are forgotten. Homebuilt planes can be very modest, but they are direct access to the human endeavor of flight, and through it you can understand some kinship with a man who’s “crowded hour” in the arena of flight came in April of 1975.”
Above is the image, published in 1975. Hedrix was not identified until 10 years later.
July 9, 2014 Leave a comment
Here are some questions that came in as comments on other stories:
Frank Stephenson writes:
“While there will be many different results, I am wondering what the average time before overhaul may be. Also what are we looking at cost wise for one of these engines and the average cost of an engine mount? I am considering selling my current conventional geared C-172 with a C-O300B engine and buying or building something a bit smaller and more efficient. I really don’t know anything about Corvair engines other than I know of several folks who have utilized them, but I don’t really know anything about their results. I have found, in general, that automotive engines don’t make really good aircraft engines, but some VW engines I have known of are an exception and apparently the Corvair engines may be an exception.”
Frank, the minimum time between overhauls on a well built engine is 1,500 hours. Ten years ago we listed 1,000 hours as a very conservative figure, since then, improvements like using valve rotators have driven the life span up significantly. The Overhaul cost on the engine is very low, on the order of $2,000 to replace almost all moving parts or recondition them. You can lean more at this link: Basic Corvair information I understand that many automotive engine engines have a poor record, but I have been doing this for 25 years, and we have earned an excellent one. You can read this link: Planes flying on Corvair Power, and see many examples. For the cost of motor mounts, just look at out catalog,http://www.flycorvair.com/, and page down to Group 4200, it lists the price of every mount we make.
I know VW engines have worked for many people, but I will put the track record for reliability, power and TBO of our work with Corvairs against any VW based engine. There is a lot of information on our main webpage, http://www.flycorvair.com/. I understand that it looks overwhelming, but better too much than to little.
Here is an important point: I don’t think efficiency is a good enough reason to move to homebuilding. Lets say your Cessna does 110mph on 8 gallons an hour. There are several Corvair powered planes that can do that on 5 gallons an hour, even some on 3 gallons an hour. But even if you were to cut your fuel costs on flying 200 hours a year from $8,000 to $4,000 per year, I don’t think it is enough motivation to send a guy to the shop for 1,500 building hours. The only people that consistently succeed at homebuilding are the people who inherently would rather fly something the personally built, and people motivate by the desire to learn new skills. I have met very few people motivated just to fly less expensively who thought in the long run that homebuilding was worth it. Consider this carefully, you may have a better time staying airborne in the plane you have.
“Sir, I am currently building a RW26 Special ll and I would like to use the Corvair engine. However, some people are telling me that it is to heavy for the aircraft. What are your thoughts and do you know of anyone who has used a Corvair engine in the Rag Wing aircraft? I read what you wrote about the Pietenpol and am encouraged that I can use the engine”
Steve, I looked at this pretty closely for an hour the other night. I tend to think that a Corvair is too big to the R-26. The 912 appears to be as large an engine as people use. Several of Rodger Mann’s designs have flown with Corvairs, but I wouldn’t call any of them an ideal match. I am guessing that a Rotax 503 is really the optimum engine for many of his designs. For a comparison of how heavy duty a Pietenpol is built, the longerons in the fuselage are one inch square spruce from the firewall to the tail post. I am pretty sure the R-26 is lighter than that.
For any plane that you are wondering about Corvair power for, the best rule of thumb is asking if the same plane has flown with a Continental o-200. If it has, a Corvair will always work in it. For a comparison of the two engines look at this link:Corvair vs O-200….weight comparison and this one:Dynamometer testing the Corvair and O-200. We also have a lot of info on comparisons to 912s at this link: Testing and Data Collection reference page. -ww.
July 7, 2014 3 Comments
Just 21 Days until Oshkosh 2014. As always, we will be there in booth 616 in the North aircraft display area (where all homebuilt companies are) I always have people ask the same questions, so here are the answers that you can always count on:
Are you going to Oshkosh?
Yes, I always do, I go every year, I am there the whole week, I am always in the North Aircraft display area. I have not missed a year since 2001, and I only missed that year because I was in the hospital in critical condition, on a ventilator. Until you read my obituary, and have it confirmed by two independent sources, you can count on me going to Oshkosh, I am planning on being there the next 20 years.
Will you have manuals and parts to sell?
Yes, we will have most of our catalog of parts on hand to sell. It is fun to go to Airventure, but the booth costs the better part of $3,000 for the week and we have about $1,500 in travel expenses. We are there to meet friends and talk about planes and engines, but primarily I am there to do business and sell parts.
Will you be giving forums?
Yes, I have done so 19 our of the last 20 years. (see “on a ventilator” above). You can just check the program for the forum times and dates. Look under all titles, William Wynne, Flycorvair and Corvair engines. Compared to any other airshow, Oshkosh has excellent forums run by their chairman Mark Forss. Over the years I have given more than 75 forums at Airventure, they are well attended and lively.
Will you look at my core engine? Can I drop of core parts with you?
Yes, I do after hours parking lot tours, and we have a hand truck and a cart you can borrow to move any part or engine. Bring it, we will make it happen, I llok at 20 engines during Oshkosh. It is a good way to confirm you are on the right track, or make a plan for the next college.
Can people come to your booth and say negative, pessimistic things about politics, America, the world and the future?
Yes, but they will not get to the end of their first sentence. For people who watch too much tv news, I gently remind them that being at the greatest airshow in the world, among friends. on a sunny day in a free country makes ‘the sky is falling’ a tough sell, and it makes them sound like Eeyore the negative donkey from Winnie the Pooh. We have too many good things to cover to waste time on negative talk.
In 10 years I have had 4 people test the theory that they paid to be at Airventure and they can stand any place, say anything they like and be as offensive as they like. What they all learned is that I am leasing the spot, and I didn’t drive 1,300 miles and spend $750 a day to be tolerant of very poorly behaved people. I know that real builders didn’t drive to Oshkosh to hear it either. Other business tolerate poorly behaved people, I have limits. Count on our booth to be an oasis of positive ideas and attitudes.
Is it really true that you made 3 young men apologize for talking during the National Anthem?
Yes, but they were not just speaking by accident, they were jerks standing just outside my booth in 2005, loudly yammering in four letter words on their cell phones during the Anthem. Each of them were bigger than me, but they were smug, about 20, very well dressed, and had evidently never been called on the carpet to answer for stupid behavior. They quickly understood that the choice was to offer a genuine apology to people within earshot, or suffer the embarrassment of having a middle aged guy with a ponytail kick their ass in front of their girlfriends. I have since been through mildly successful voluntary anger management training, but I would probably still fail under the same conditions. I know some of my old friends thought the moment was ‘classic’, but I not really proud of it.
Read about last year at this link:
comments from Corvair builders:
Tammy Duckworth, above center, and her husband Bryan Bowlsbey, left, with the Corvair All Stars at our booth at AirVenture 2009. From the right, Mark Petniunas from Falcon Machine, Dan Weseman from Fly5thBearing.com, my wife Grace Ellen, myself, and Roy Szarafinski from Roy’s Garage. Tammy and Bryan are old friends. Tammy had recently accepted a post as Assistant Secretary of Veterans Affairs in Washington, D.C.