In my past two columns I put forward the idea that for the future of general aviation, we need to update technology to meet the demands of a changing world. I would like to further that discussion and answer a few of the comments from readers.
The first step is to forget the 100 unleaded avgas program and go to a two fuel system. The two fuels would be very similar, with one being the present 100LL and the other being the same fuel only without the lead. It would have an octane of around 94 lean rating (call it 94UL) and would meet all of the other properties of 100LL.
Now I know there is the problem of FBOs needing two fuel systems. But many of them presently have two systems or sell mogas.
The advantages of the two fuels are very significant.
One of the big advantages for 94UL would be that it meets the ASTM D-910 specification for 80/87. The spec only calls for a maximum of 0.5 g/gal of lead. This means that all 80/87 engined aircraft could legally use the fuel without an STC or any other changes. The fuel would be completely compatible with 100LL and pilots could go back and forth with no concern, for example, during break-in of a new engine.
It would be compatible with all fuel systems with no concerns about vapor lock or any other fuel problems such as ethanol.
The storage stability would also be similar to 100LL, which would create a new market for FBOs, including antique and classic cars and low usage engines or vehicles.
If the fuel could be made widely available, just about every classic car owner would buy the fuel to keep his vehicle from becoming gummed up by normal mogas during extended storage.
Also, since the fuel would be unleaded, it could be shipped by pipeline. That could possibly lead more refineries to consider producing it.
New Technology Aircraft Engines
Back to why we need newer technology engines.
Just image what it would be like to go flying on a cool fall day in a Piper Archer with a four-cylinder turbocharged auto engine. You would go out to the airport, remove the tie-downs, do your airframe checks, and maybe check the oil, just for the heck of it.
Then you would get into the aircraft, turn the key, start the engine and taxi off.
No need for pre-heat, no hitting the primer and wondering if you over-primed and flooded the engine, no setting the mixture strength, no mag checks, nothing. Just get in and fly.
Then once in the air, no mixture adjustment or anything, just enjoy the thrill of flight and the scenery.
Several years ago, I had the pleasure of flying in a 172 with a Porsche engine. Once airborne, I was at first a little nervous because it was so quiet and smooth. We removed our head phones and could talk in a normal voice and even talk on the mike without raising our voices. The lack of vibration was also very noticeable.
The reason for the smoothness is that with an O-360, there are only two power pulses per revolution of the prop, and each pulse hits for about 45 hp at full power at 2,200 rpm.
With a new technology engine running at, say, 4,400 rpm, there would be four pulses per revolution and each one would be only about 22 hp. This quietness and smoothness would greatly increase the pleasure of flight and reduce airframe problems and pilot fatigue.
Another big advantage for the new tech engines is that they could use automotive oils. This may not sound like a huge thing, but it is.
Other than the cost, the big deal is that automotive oils are ash containing. The zinc additive will greatly reduce wear, but the best thing is that the ash containing detergent will keep the engines much cleaner and fight rust.
These additives cannot be used in aircraft oils because the aircraft engine burns too much oil and the additives would lead to pre-ignition. Not a problem with a new technology engine.
This means that cylinder rust and, more importantly, cam and lifter pitting would be eliminated.
When you finish your flight, you just tie the plane down and walk away. No heaters, blankets, or anything.
Then on your next flight — whether it is next week, next month or even next year — the 94UL fuel will be good and the ash containing oil will protect your engine.
The auto engine would be liquid cooled, so a tighter cowl could be built to reduce drag in flight. And the cooling liquid could be used for a more effective and safer cabin heating system.
Then there is the emissions thing. By going to 94UL we will reduce the lead emissions and not risk the problems associated with unleaded fuels in bigger engines.
In addition, the CO emissions from the auto engine would be reduced about 90% from the current aviation engine, again a safety concern.
There would also be a very significant reduction in unburned hydrocarbon and oxides of nitrogen emissions.
Plus the fuel economy of the auto engine would be greatly improved over the current engine, which would mean a similar reduction in CO2 emissions.
Stopping the Downward Spiral
There are many more advantages for a new technology engine, from improved performance and reduced maintenance.
Also, since Corporate Average Fuel Economy (CAFE) regulations for new car fuel economy have been implemented, car companies have reduced the weight of auto engines to the point that for a similar horsepower engine they should be very close to that of an aircraft engine.
There are many engine options from the many auto companies that could be used.
This may not be a perfect solution, but it beats sitting here and watching the general aviation business continue its downward spiral.