Here is the first run on our newly built engine dynamometer. There are many types of engine dynamometers.
One of the most simple and easily made measures the engine's torque reaction. Our own stand has a motor mount
which is free to pivot along the crankshaft axis. This is restrained from rotating by a hydraulic cylinder.
It is a simple calculation verified by a simple test, and you can ascertain the amount of torque the engine is
producing at any given instant by reading the hydraulic pressure. It is accurate, and if you have the capability
of measuring the rpm of the engine very accurately at the same moment, a simple calculation will give you the
exact horsepower that the engine is producing. Shown above is the very first run we did on the dynamometer.
Its details are still being finished, but it works very well.
Above is the view of the dynamometer with the engine removed. Its operation is very simple. Everything seen in
blue rotates on the crankshaft's axis. If you look closely, you can see that the bearing is the front spindle,
hub and wheel removed from a late model Corvair. The bed type mount is slung low so that the crankshaft
centerline lines up exactly with the spindle. The reinforcements below the engine contact a bearing at the bottom
of the stand for additional support. This is a Corvair blower bearing rolling sideways on a steel plate. It
effectively has no drag. Below the spindle is the mounting point for the hydraulic cylinder. The green oxygen
bottle has been converted to a gravity feed fuel tank on the test stand. It hold 2.5 gallons of fuel, and has a
very accurate sight gauge on it which allows precision measurement of fuel burn.
Another view of the first run is above. Just ahead and above the battery is the hydraulic cylinder. A stainless
braided line running out of the picture goes to the remote gauge. Our rpm measurement is by digital optical
tachometer. This is one of the few types of tachs accurate enough to give good test information. Many people
will recognize the chassis of the dynamometer as our previous engine run stand. The old stand served us well,
and broke in many famous Corvair engines, such as Mark Langford's 3100. Although we never kept count, I'm pretty
sure 50+ engines were run on it. The new dynamometer is capable of everything that the old run stand could do,
plus its obvious new function of measuring horsepower. In the coming year, we'd like to run as many engines as
possible and anyone converting a Corvair for flight reading this is certainly welcome to bring their engine for a run.
We took the time to manufacture a very special intake manifold for the dynamometer which is compatible with
any style of cylinder head used in Corvair flight motors. Details like this will make installing and running engines
a quick and simple process.
Gus monitors the engine run, above. Note the newly constructed heavy duty baffle box to provide cooling air to
test engines. I've said it many times, but it's worth repeating that you should not run your motor even briefly
without a cooling system in place. The carburetor in this run is an MA3-SPA from an O-200. This will be the
dedicated carburetor on the dynamometer, although we will be able to evaluate others.
The propeller is a 72" 2-blade Warp Drive. In the background in this photo is the Corvair Trimotor fuselage.
Above is another view of the running engine. The baffle box is made of 50/1000" aluminum, although 25/1000" would be
plenty for a box you're only going to run for a few hours. We plan on getting a lot of work out of this, so we
built it heavy duty. You'll notice that the 12-plate oil cooler is outside the baffle box. Engines run on the
test stand traditionally have very cool oil temperatures. I kept the cooler outside the baffle to give the oil
a chance to warm up. When set up for flight inside a cowl, the engine will have normal oil temperature and it
will be appropriate to have full air flow over the cooler.
Here is the same engine pictured running on this page. We built this engine specifically for the Corvair Personal Cruiser, a single seat aircraft designed for Corvair power. This engine will be installed on the prototype, now
under construction. In the photo above, the engine is sitting on the mount for the Cruiser. Shown in silver is the
intake manifold for the aircraft. We built this from mild steel tubing. The horizontal inlet is built specifically
to mate with an Ellison EFS-3A. Also of interest, note the layout of the sparkplug wires. When oriented like
this, the cap can be removed for inspection without removing the wires. Additionally, the distributor can be
rotated to set the timing without the wires becoming slack or taut. Doing dozens of engine installations over the
years has allowed me to perfect small details that allow the operation and maintenance on the motor to be done
far more easily.
Very shortly, we'll provide the next batch of photos sharing the test data and the calculations. Additionally,
we'll show you the calibration procedure, which allows everyone to understand how accurate this simple machine