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In the photo above, right, is Ivan Carlson, Corvair/Super Pulsar builder from Louisiana, and myself, standing in front of his running 2,900cc Corvair. Ivan started this engine at our shop during Corvair College #8, and returned last week to finish it off and give it a test run on the dyno. This engine was particularly challenging to build. Kevin worked directly with Ivan, and had a lot of days in bringing it all together. The engine is based on 90.5mm VW cylinders. It has roller rockers, which required modifying the valve covers and getting custom pushrods made. It has 140 exhaust stacks in 95 heads. This modification required extensive reworking of the stud holes in the heads, the exhaust stacks and the pushrod tubes, which additionally had to be ceramic coated. For those with sharp eyes, you'll notice that the engine is also reverse rotation. It has one of our Front Starter Kits installed with a special starter. The prop it is turning is the 72x48 Sensenich from Grace's Taylorcraft. (This is an extreme cruise prop for Grace's C-85 engine.) The Corvair turned it substantially more RPM static, despite the fact that this prop is designed to operate well below the Corvair's torque peak. The main reason why I do not recommend highly modified engines like this is that they are much harder to build than standard engines and offer only modest power increases over standard engines. Ivan's a very determined builder who's willing to travel to our shop and do what it takes to resolve technical issues in a first class manner. (At times, this means being patient while spending money.) His unique position allows him to have one of the nicest Corvair engines we've built in our shop lately.
John Locke, above right, flew in from Texas to work on his Corvair engine for his own Super Pulsar. John made some really good progress, and got a preview of how his own engine will run. Gus flew both builders in the 601 on long familiarization flights. This way, they'll be well acquainted with normal, smooth Corvair operation when their own airplanes are ready to take flight. His friend Linda, in the foreground, came along to lend a hand with the engine. She got along great with the hangar gang and did some flying with Gus in the 601.
|Subj: Dual Alternators|
Have you thought at all about how to install dual alternators on the Corvair engine? This would seem to be a useful option (with dual batteries and regulators) in an all-electric, non-magneto system.
My engines are all torn apart but it would seem to be possible to install your new front alternator brackets on both the right and (flipped over) on the left side of the engine and run a single belt over all three pulleys. This would not be the optimal set-up as the belt would be a potential single point of failure and might not have enough contact with the pulley on the crank. Instead it would appear that there is plenty of room between the existing Pulley and the Prop Hub to install another Pulley. This would allow the use of two independent belts.
|Craig Payne, Utah, Manual #6154|
|Reply from WW:|
|With the existing single alternator, battery, ignition system we have, you could start the engine,
take the generator offline, and operate the ignition system and the electric fuel pump for hours off battery
power alone. This is one of the great advantages of a points-based ignition system. They have very low power
consumption, and will operate at greatly reduced voltages. Conversely, electronic ignitions are big power
consumers, and many of them refuse to operate below 10 volts. In all of our years of flying John Deere
generators, we've never had any type of a failure, including losing a belt or regulator. If we were ever to
experience such a failure, our current system would provide a great amount of time to select an airport, fly to
it and repair the problem. Additionally, if you had some type of problem with the battery, we have test flown
our ignition system operating straight off the John Deere without the battery in the circuit.
Many homebuilders go through a phase where they want to incorporate complex redundant systems. Keep in mind that your plane only has one set of control cables, one main wing spar, one prop, etc. Many homebuilders forget that redundant systems on military aircraft serve an entirely different philosophy than sport airplanes: The redundant systems on military aircraft are there to increase the chances that the aircraft can get through to its target. With their philosophy, the mission will continue no matter what damage is suffered or which systems fail. The target is the goal, and the plane and crew are expendable. Conversely, our goal is to simply have fun and enjoy ourselves. This means simple, reliable, proven systems, and in the highly unlikely event of a failure, simply flying to the nearest airport and fixing it.
What was the name & type of tach that counted flywheel teeth?
Tim, Manual # 6113, East Central Ohio
|Reply from WW:|
|We use a Stewart Warner tach. The one we have installed in our 601 is a 0-3,500rpm unit, which has a full sweep, allowing you to clearly see a 25rpm difference. Because it works by counting flywheel teeth, it is entirely divorced from the ignition system. The Stewart Warner part no. is 82636. If you look at our 601 Web Page, you'll see the tooth counter attached to the front alternator bracket. I've used this tach in many Corvair powered airplanes over the years. I like it because it has very smooth operation, and it is extremely accurate when checked against our digital optical tachometer.|
|Subj: Corvair and Sport Aerobatics|
You have made several statements regarding your considering the Corvair to be unsuitable for aerobatics, citing crankshaft design and inverted system complexity. If aerobatics are limited to positive 4.5 and momentary 0 to negative G loadings, do you still consider the engine to be unsuitable for this use? Considering installation for Cassutt. Engine would be built with no electrics or starter for weight and simplicity. I don't mind being restricted from outside and sharp snap manuevers.
Thank you. Your web site is very professional and informative.
|Regards, Thomas A. Berthe|
|Reply from WW:|
|Thank you for the nice comments about the Web site. Grace Ellen puts a lot of hard work into it. The two most popular engines of all time in the Cassutt would certainly be the C-85 and the O-200. Neither of these engines in their common forms are considered aerobatic. The Continentals use a wet sump oil system, just like the Corvair, and any time you subject these systems to negative G, they're going to suck air instead of oil. I suspect in routine flight that a lot of Cassutt guys did this, but technically, you can understand why it's a bad idea with any wet sump engine. As you understand, aerobatic maneuvers put enormous loads on the crankshaft, far beyond what most people estimate. While the Corvair has a very strong forged steel crankshaft, I'd be reluctant to encourage anyone to fly aerobatics because the long history of flying Corvair engines was done in normal maneuvers. There isn't a lot of flight time done using them for aerobatic applications. I strongly suspect that Rotax, Jabbiru, and the VW suppliers would give you the same perspective on their engines.|
|Subj: Engine Assembly|
I have a couple of questions. First, what are your thoughts on builders who want to build the engine but are not able to attend a Corvair College, do you advise against this? Second, is there any type of package for someone wanting to order all the Assembly Videos?
Thank you for your accessibility.
|Chris Barrow, NC, Christavia MKI|
|Reply from WW:|
|Over the years, we've sold several thousand Conversion Manuals. In the first eight
Corvair Colleges, we've had perhaps 400 builders attend to learn and work on their engines. In between Colleges,
we've hosted perhaps 400-500 more builders who came to do the same. These visits vary from a builder stopping by to
have us inspect his core engine before he started the rebuilding process, straight through people who purchased a
complete engine from us but wished to spend several days in the shop while it was assembled so they'd know the engine far
better than most homebuilders know their powerplants. Even with all these visitors added up, the great majority of
our active customers have never been to a College or visited our hangar in person. Our Manual, Videos and instruction
style assume no prior experience with engines, nor do we assume that most builders will have the opportunity to
attend a College. I purposely selected the Corvair as one of the few engines that met the flight requirements, but
additionally had the characteristics of simplicity and ruggedness that would allow us to teach builders in remote
locations how to complete and operate their own engines.
During the year, we offer special deals on products to active builders through our newsletter, The Corvair Flyer. Subscriptions to the Flyer cost $20 a year for U.S. builders, $25 for international builders. Over the year, we offer multiple opportunities to recoup the subscription price. In The Flyer, we occassionally offer discounts on video purchases.
I ran across this information on the MA* - SPA carburetors. You already know all this information but I thought you might want to pass it along to your customers: http://www.kellyaerospace.com/articles/Accessory_AMT.pdf
Also I was looking at the Ellison site and they recommend that you install a priming system when using the EFS-3A. Is this needed on the Corvair engine, and if so do you recommend the manual primer or the electric one?
|Larry Kyle, New Palestine, IN (I met you at Casey, IL)|
|Reply from WW:|
|Thank you for the link. Kelly Aerospace makes a lot of parts for certified aircraft.
An Ellison is an excellent carburetor, but you're correct, it does require a primer for clean starting. An MA3-SPA with an accelerator pump does not.
The two options on primers are the traditional hand pump or an electric primer. We've flown and used both types. If I were installing an Ellison in a 601, which would use our dual electric fuel pump system, I'd opt for the electric primer because you already have the rest of the system to run it.
|Subj: Engine Cleaning|
This is a really dumb question, but could you provide a step by step on how you get the case and heads so clean? With all the parts you sell, the Vair engine is almost an "assembly kit" with the exception of teardown and cleaning the core (future video maybe?). So far this has been the most time consuming/hardest part of the conversion. I'm ready to assemble the lower end but I'm not convinced the case is really clean enough to hold paint. I'm working on the heads now. They have been degreased but now what? Glass bead, walnut, plastic? I know you've said don't glass bead, but then it seems like a lot of people are glass beading and all of the shops I've talked to glass bead their aluminum parts. I want them as shiny as those on the fantastic looking engines you just delivered on your Midwest Tour, so if glass beading is definitely out, it looks like I'll have to get them cleaned up myself before I take them in for the valve job.
Also I have a set of the grooved rocker balls from Clark's. I noticed Clark's sells mated pairs of rocker arms and balls. I'm planning to use my original rocker arms with these new grooved balls. Do I need to "mate these up" or just let them "mate up" in operation?
Thanks, Gunther Zion, Manual 5086, Greenfield, IN
|Reply from WW:|
|While automotive shops may use glass beads on aluminum parts, you will not find a practice like this in
the aviation industry. Every now and then, somebody will bring a case by our shop that has clearly been glass beaded.
It takes but a few moments to show people a little corner or a passageway that has half a thimble full of beads waiting
to destroy the engine upon startup. Even if the case is really clean, the lifter bores and bearing seats are ruined by this
type of procedure. The heads are less critical, but still intolerant of glass beading. While we now own an environmentally
friendly high pressure wash tank, we traditionally cleaned cases with bristle brushes and a regular wash tank, filled
with mineral spirits. We used to figure about 2-3 man hours to clean a case with a stiff bristle brush and fresh
mineral spirits. You will not be able to remove all the stains in the cases, but you should be able to have it clean
enough that a regular white piece of paper, when pinched against any surface on the case, will not pick up any dirt.
We finish off heads in our walnut blaster. Both heads and cases are cleaned to the point where they may have stains or discolorations, but they are completely free from any type of dirt particles. In our shop, all the cases are painted to improve their looks. The Plastikote paint we use is impervious to flight temperatures, and will stick tenaciously without primer on the cases. It has the additional plus of drying in half an hour. The heads on the engine you saw on the trip were very lightly painted on their exterior surfaces only with a color called Cast Alumninum. Under absolutely no circumstances should any interior surface of the engine have paint on it. It all takes time, but there are no special tricks or shortcuts to a good looking and clean engine.
Engines built in our shop utilize reconditioned GM rocker arms with grooved balls from Clark's. If the rocker arm is not damaged in the pivot area, I've found that they will work with new balls and mate in operation.