Corvair College #23, 2700cc Engine, Spencer Gould, SP-500
In the above photo, from left to right, Spencer Gould, Dan Weseman and Mark “Petz” from Falcon Machine at work on Spencer’s engine at Corvair College #23. Dan is covering the installation of his 5th bearing onto Spencer’s engine. Originally built as a plain 4 bearing engine, Spencer elected to add Dan’s bearing, a fairly easy upgrade that does not require the engine to be disassembled. Dan’s presentation on how to do the process complemented the clear directions that come with his bearing.
Above is the same process from a different angle. Here the prop end of the engine with the Safety Shaft is sticking straight up. Installation is easier on the bench, and it is easiest if the pistons and rods are not yet installed, but Dan has demonstrated many times that the upgrade to his bearing can be done without ever removing the engine from the airframe. He now has well over 200 bearings in the field, and they have been proven over 5 years of service. Upgrading an engine requires a shorter hubto keep the same length of Studs, Shaftand cowling. The Wesemans offer this machine service to builders who already have one of our Black Hubs or a Standard length Gold Hub. Builders that are planning on using a Dan bearing from the start order a Short Gold Hub from us.
Above, is a good look at the clean lines of an engine equipped with a Front Starter and alternator. Note that the engine has just one oil line on it, running from the Gold Housing to a Weseman Bearing. In its final installation, the engine will have a Gold Sandwich between the Filter Housing and the filter, and two short lines feeding a large cooler mounted on the engine baffling. This is another view of our new Starter Bracket. The outboard side of the triangular bracket is slotted allowing the adjustment of the starter engagement. This eliminates the previous system that had a drilled link plate. Spencer’s engine has the oil fill in the top cover because it is going on his single seat design, and he is planning on a form fitted cowling that would come too close to the right hand valve cover to have room for our standard oil fill location. The left hand valve cover has our standard crankcase vent line and oil return. The engine uses our Short Gold Hubbecause it has a 5th bearing. The bearing is one of the Weseman’s original cast housings, before they went to billet CNC production.
Another view of the engine. The welded on intakes were welded on the heads by Mark Petz at Falcon Machine. Like most flying Corvairs, Spencer’s engine has one of our E/P Distributors. Oil filter is a K&N 1008, the plugs are AC-R44Fs, my first choice for both of these. The dip stick is an aftermarket one for a 289-302 Ford, with the tube shortened 5″. The engine hardly needs more than a set of ignition wires and a baffle set to be installed on an airframe. None of the engine systems need to be mounted on the firewall: The engine is largely a self-contained, neat package. The engine will be flown with a HD oil cooler because the airframe is designed for strong maneuvers and solid acrobatic work, and excess oil cooing makes sense on a plane that will be flown at full power and slow climb speeds. On the run stand, engines can be operated without oil coolers because the oil comes up to temp very slowly with the engine uncowled.
Above, Spencer’s engine at power on the stand. Note the size of the cooling baffle we use on any engine we are running on the ground. We recently had a builder extensively damage the engine he built by running it on the ground without any type of cooling baffle or cowling. In every photo we have of running engines at the Colleges, especially brand new ones being broken in, they have a generous amount of cooling air being pumped through them by the baffle. Prop wash over an uncowled engine does not work, period. Without a cowl or a cooling baffle box, none of the air has any reason to flow down through the cooling fins on the head. How long does it take to hurt the engine? How much running is OK? Answer the question for yourself this way: If you just spent $5,000 and a lot of time to rebuild the V-8 in your classic muscle car, how long would you run it without a radiator?
Actually this isn’t a fair comparison. A v-8 in neutral turning 2,000 rpm is only making 10 or 15 hp, it is not pulling any load. It has a several hundred pound mass and lots of oil to heat up. Conversely, a Corvair with a flight prop turning 2,000 rpm has to be at half throttle and may be making as many as 60 horses. It doesn’t have the mass to heat soak either. You could run the V-8 longer without damage.
Keep in mind, if you hurt your newly overhauled v-8, it may leave you by the side of road later. If your flight engine is wounded by cooking it during break in, it may choose to get even with you later, and it is much more likely to do so on a full power climb out than it is idling on the ground. In the end, what exactly was to be gained by running the engine on the ground without cooling? Building a box too much work? Few scraps of sheet metal cost too much? Building the most elaborate cooling box will never take 10% of the time nor 5% of the cost of rebuilding your engine. The longest time I ever run an engine without a cowl or cooling box (once it is fully broken in) is 45-60 seconds, and only 5-10 seconds of this are much above idle. I would do this while setting the timing on an engine after maintenance. On many of our cowling designs like the Zenith cowls, you can just pull the top hinge pin on the passenger side and remove the top access panel. The cooling system will stay in place with the exception of a 4″ square hole. You will have full access to work with the Distributorand set the timing. Our cowling design took factors like this into consideration, and that is why it makes a lot more sense than trying to scab together a cowl from leftovers of some other engine.
Above, Spencer enjoys the finest form of air-conditioning on the planet, prop blast from an aircraft engine created by your own hands. A close look at the exhaust on the run stand shows that I have oxygen sensors on both sides to run an air/fuel meter (lean-rich gauge). Initially, I liked the idea, and a number of well-known Corvair pilots like this instrumentation as well. Here is the turn off for me: The sensor works on a tiny signal difference, and it is very prone to any type of grounding issue. This is a pain, but not too hard to overcome. My real objection it that when the device loses its signal, its default position is reading perfectly in the green arc. I find the very concept annoying. Would you use an oil pressure gauge that indicated 45 pounds every time the wire was disconnected? How about a fuel gauge that always read 1/3 full when it was having an issue? To me, I want instrumentation that when it fails, it clearly indicates that it is dead, it doesn’t provide misleading info. There is probably some electrical reason why the air-fuel meter reads green when it is dead that makes sense to an engineer at a computer, but if I put it in a plane, it has to make operational sense to me. Lest you think I am making a mountain out of a molehill, than consider that the airliner hitting the 14th street bridge in D.C. was primarily caused by an instrument error on the EPR gauge; the airliner that went into the Everglades 30 years ago had the crew fixated on a failed instrument light; there are enough stories about professionals being undone by faulty instrument data that homebuilders should consider this issue with attention. In my personal opinion, almost any Corvair engine can be well served by 2 simple EGT probes in the exhaust. EGT systems are stupid reliable, and when they are disconnected they don’t read.
Above four of the major contributors to the modern Corvair movement: From left, Mark from FalconMachine.net, Dan Weseman from SPA.com, myself, and Spencer Gould.
Today, Spencer’s day job is aeronautical engineering for the world’s greatest aircraft powerplant company, Pratt-Whitney. Contrary to the popular image of serious engineers being challenged by practicality, Spencer is a multi-faceted renaissance man of aviation. He is a very skilled pilot of complex aircraft, he is the master of CAD drawing and machining, he can fly any RC aircraft with skill, he has designed and flown dozens of them. He designed and has built 98% of his own composite acrobatic aircraft, the SP-500, and has a broad array of practical knowledge in the world of aviation. If you need a technical solution to a structures issue, a finite element analysis, or a process, Spencer always has valid input. In the years between his graduation from Embry-Riddle Aeronautical University and Pratt, he worked as a powerplants engineer for Piper in Vero Beach. During that time, Spencer was an adjunct member of The Hangar Gang, and covered a lot of our CAD work. Designs that I had for the Gold Oil System, the modern Hubsand our 5th bearing were refined by Spencer’s CAD ability, and they went directly to CNC production from code we e-mailed to the machine shop. He was and remains a very important force multiplier in our efforts, an asset that few other engine programs could claim to match.
If you are new to homebuilding, stop and think about this: The Corvair not only has appeal to people whose day job is far from aviation, but it also has great appeal to builders like Spencer who are immersed in aviation, men who understand all the issues involved in powerplants. Spencer could afford any piston engine he wanted for the front of his aircraft. Yet he selects the Corvair because after careful evaluation, it all adds up to the right choice for him. The engine isn’t for everyone, but no builder new to aviation need worry that the engine isn’t capable of meeting the demands of educated professionals and amateurs alike.-ww