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.
Emissions
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.
Marie Brill says
There is already a UL94 fuel on the market produced and distributed by Swift Fuels
Dave Anderson says
That is interesting that new aircraft engines with new tech are able to used automotive oils. It would be good to get an aircraft engine like this and keep it properly maintained so it ran well. Getting aircraft engine overhaul is something I would want to look into if it were necessary.
Jeffrey Zwar says
I stand corrected. The testing was done with AGE-85.
In part, Cessna’s document also issues this warning: These tests and evaluations also suggest that operational safety may be compromised by the use of ethanol-based fuels.
Cessna recommends against the use of any levels of ethanol in fuels used in its aircraft, not only AGE-85. Its conclusions are in stark contrast to claims made by AGE-85 proponents, for instance at the American Coalition for Ethanol or at e85Tips.
Cessna Service bulletin SNL10-5 issued May 18, 2010
Jeffrey Zwar says
Your comment may leave readers confused about any role that ethonol may currently have in the general aviation fleet. There is no role for E10 in piston engines. Cessna made that absolutely clear years ago after their testing of it revealed that up to a 40 percent increase in fuel flow was required to control detonation. Some airframes do not have the capacity to accommodate that increase in capacity.
Henry K. Cooper says
Are you sure you’re not talking about 40 percent more fuel when using straight ethanol? That would make sense. A 40 percent fuel flow increase using E10 would result in a very rich mixture.
Maybe I’m confused.
Jeffrey Zwar says
My recollection is that Cessna’s testing was conducted using E10. One of the things that their testing indicates to me is that E10 has much less energy than pure gas measured by volume. Perhaps as much as 40%. Hence the increase in flow required to keep detonation from occurring. Cessna sent the results to all Cessna owners. I imagine you could get a copy of it. They found other objections to it’s use as well, such as corrosion and plugging of fuel filters.
Henry K. Cooper says
Now I think I understand. What they must have been testing is either pure ethanol, or E85, which is 85% ethanol mixed with 15% gasoline. E10 is what we currently pump into our vehicles…..10% ethanol and 90% gasoline.
West Virginia University tested pure ethanol in a Cessna 150 back in the mid 1990’s, and a fuel injector was installed in the intake manifold upstream of the carburetor in order to deliver approximately 40% more fuel when pure ethanol was used.
I had issued an experimental airworthiness certificate for the aircraft when I was with FAA.
Sandra Stahl, Executive Director of the Montgomery-Gibbs Environmental Coalition says
I agree with the two fuel system. Swift Fuel’s unleaded UL94 is FAA-certified for use in up to 65% of the US piston fleet; up to 100,000 aircraft are already certified to use the fuel, based upon existing Type Certificates and/or Autogas STC’s. An additional 25,000+ aircraft, those whose engines are rated for minimum Grade 91/96 Avgas, are eligible to purchase an FAA Supplemental Type Certificate (STC) to use unleaded UL94 Avgas.
The problem is getting GA airports to start offering it. Excuses include waiting until the 100 unleaded avgas program finds an alternative to leaded, but that could be years in the future.
Another excuse is that UL94 costs around a dollar higher per gallon than leaded. However, pilots would easily recover that cost because using UL94 results in increased spark plug life, overall decreased engine wear and tear, significantly decreased deposit build-up, and no acidic corrosion compared with 100LL. That results in nearly doubling maintenance intervals.
Joe Henry Gutierrez says
O.K. then, lets not forget the propane powered engines, that work just as well as gasoline, are 1/10 the expense of a gas engine and produce the same h.p., by the way, one gallon of liquid propane equals 155 gallons of gas !! that’s right, one gallon of liquid propane will make 155 gallons of gas !! Again I say its all about money,, If propane comes to the market just think of all the people not being able to continue to rip us off.. There has been aircraft made to run on Propane and were very successful and inexpensive, very quite and no omissions what so ever, now that would solve the omission problem having lead producing exhaust, wouldn’t it?? So why aren’t we running propane in our aircraft? You think there’s not enough green? I think so, everything is a big rip any more, nobody cares for doing the right thing, Its all about making a large profit and nothing more…I prefer propane over electric any time…
Henry K. Cooper says
The last I heard, a propane engine IS a gasoline engine fitted with a carburetor for gaseous fuel. I know, as I worked on them for a propane distributor. How these can be considered to be 1/10 the expense of as gasoline engine is beyond me. And any tank that holds liquid propane is very heavy.
Henry K. Cooper says
One gallon of propane makes 155 gallons if gasoline? In what sense?
A gallon of gasoline contains approx. 115,000 BTUs of energy. A gallon of LPG contains about 91,330 BTUs of energy.
Not sure where your figures come from, but check it again.
Bob Martilla says
I would like to point out that there is no sub-200 hp non-turboed Lycoming or Continental out that won’t run on 92UL with no ethanol in it. That’s 70 percent of all of the GA fleet. That means that the majority of owners are indirectly subsidizing the rest of the users. I have an old 82 octane E-225 Continental that I have to lean during taxi with 100 ‘LL and I would use 92UL from the marina in a second if I could get it at the airport.
All of us bought into the myth that we had to have a single drop-in replacement for 100LL or the sky would fall and we would all be grounded. Well folks by doing what we were told to do we actually made things worse. It’s been over 15 years now and we are at the point where two of the makers have abandoned the effort out of frustration only to go to the STC route which will be even more expensive to the end users. US! It would have been far cheaper to use the development money to change every airplane engine to electronic ignition and use 92UL with no ethanol in it from a gas station. This would have opened the door to innovation to modifying old engines and a whole new generation of new designs. Now we will have neither and no fuel to go in them. Brilliant. I suspect that the leadership of the aviation groups and manufacturers along with the oil companies knew there was no chemically or economically viable solution here but didn’t want to go with technology for the engines that would work in the long run. We chose the wrong path and the damage may already too great for the piston engine market to survive in the long term. Thank God for the emerging electrical technology in the future as you will NEVER see a Connie or a Lycoming in any of the flying cars in ten years.
Marcel says
Ben, can you tell me more about the 172 with the Porsche Engine? I have a Cessna 175 and interested in any options. Running great now, but would like to learn about the 172 option.
Manny Puerta says
A Lycon built IO-360 would be my choice for a 175.
Kurt Goodfellow says
I’ve been flying your “dream” for almost 5 years and over 600 hours. I built a Glasair Sportsman (Two Weeks to Taxi program) with a Continental CD155 diesel. It meets all of the criteria you discuss in your article. It is certainly modern. It is ultra smooth. No worries with pre-heating, priming, carb heat, icing, mixture control, prop control, shock cooling, etc. And it runs on Jet A, which will be readily and plentifully available for decades to come, usually at a lesser cost than 100LL. It’s a more stable, safer fuel, and can be stored long term. It is a derivative of a Mercedes Benz auto engine.
As you indicate, when it’s time to fly, you just get in, start it up, and fly it. Set the single power lever to the percentage of power you want, and you’re done. Nothing could be simpler. The Sportsman cruises all day at 125-130KTAS at 75% power, burning 6.1 gph. It’s pretty hard to beat. I’m sure the engine would be even more efficient if it were mated to a cleaner airframe. I’ve been flying for over 35 years, and I have never enjoyed an aircraft more than the diesel Sportsman.
Yes, it was expensive to buy initially. But just imagine how the cost would come down if more GA operators recognized the benefits of diesel aircraft engines and switched to diesel power. Even at today’s prices, the fuel savings more than covers the extra initial cost over the life of the engine…
Kudos to Piper and Diamond for offering diesel options. Why Cessna gave up on it so quickly is a mystery to me.
Even the Diamond Hybrid aircraft uses a diesel generator. As far as electric aircraft go, I’ll agree with the C185 owner. We’ve got a LONG way to go before cross country electric flight is even possible, let alone practical.
Joe Henry Gutierrez says
It’s all about “money” and of course “greed”. Technology is good and it’s there for anyone that wants to improve on it, but the real truth is, if there’s not a lot of money to be taken from this, it will never fly…..Everything is based on profit, (money) don’t be fooled by all the hoop la that it’s the FAA or the EAA or whatever you choose. Money money money that’s the goal. Remembering back to the 2nd. world war the need for high octane fuel was needed for the heavy bombers etc. like 130 – 150 octane for these aircraft, the formulas were delt with in just a very few months. This was in the 1940’s technology and presto no problem, we have high octane fuel for what ever aircraft we have and need. So all this BS about having to invent a new engine to meet the fuel is malarkey pure and simple. To come up with a new fuel is cheap, there just is-ant enough profit to satisfy the greedy..
Henry K. Cooper says
With AvGas being way less than 1/2 of 1 percent of the total gasoline consumption in the US, messing with its formulation sure isn’t worth the effort or the cost. Hard to tell how many millions ($$$) has already been pissed away for no good concrete reason!
JimH in CA says
Henry,
Very true.! and 90% of the GA aircraft can use 93 octane ‘auto gas’, but it cannot have any ethanol, so we can’t use gasoline from any gas station.
If we could use 93 E0, it would save me $1.00 to $1.50 per gallon. I burn 8 gph and in 1,500 hours I would save enough to pay for an engine overhaul….$18,000.!
Only the high compression engines, [ 9:1 cr ] and turbocharged engines require the 100 LL.
The rest of the engines have 7:1 compression ratios and were certified to use 87 octane gas.
Henry K. Cooper says
Ethanol-free MoGas is available at certain gas stations. You may have to Google to find one. Test kits are available for not much $$ to test for ethanol so you know what you’re getting. Certain engines can use 87 and 91 octane MoGas. Bear in mind auto gas octane is calculated by the R plus M /2 formula (research number plus motor number /2), whereas AvGas octane numbers are by the Motor (M) method. There is no direct correlation between MoGas and AvGas octane numbers. Check the Peterson autogas STC specs for more info. Peterson is not the only autogas STC holder, either.
Regards
JimH in CA says
Henry,
thanks. But there are no gas stations in California that sell E0 fuel, not counting ‘race gas’ and it costs more than 100LL.
There aren’t any within the 700 miles flying range of my old Cessna…
We have the Peterson STC for 87 octane mogas…
Henry K. Cooper says
Didn’t realize you were in CA. That’s a whole ‘nother country!
JimH in CA says
Ben, all,
I’ll copy my comments from Oct 22.
GA aircraft engines are best suited for aviation use. However they can be made more efficient without reducing their reliability by adding electronic fuel injection the electronic ignition. These are available now for experimental use and are well proven to improve power and fuel efficiency.
There are a number of auto engine conversions; VW, Sabaru, and Corvair. These work well for low power needs, 100 HP. But the current, modern auto engines normally run at 10-20 % power and and rarely run near 75% power for any duration. The turbo engines I drove had a max. time running at max boost pressure of 10 psi., 10 seconds.
I don’t think an auto engine, running at 65- 75% power would run for long without overheating or mechanical failure.
Most cars will run to 200k miles. but they average about 30 mph, [ low power levels ] ., or about 6,000+ hours. Running these engines at 75% power would probably shorten their life to 1,000 hrs, or less.
The low GA aircraft production volumes do not lend their manufacture to any automation, other than CNC of parts, as the RV series is so successful in doing.
GA aircraft are in the same category as exotic super cars; low volume, high cost, and hand crafted.
Adding electric motors, controller and batteries can assist on takeoff, but are ‘dead weight’ in cruise flight, and reduce the useful load, like additional fuel and passengers.
Francis Soltis says
I have been flying a modern fuel injected ROTAX 912iS Sport with dual fuel injectors, alternators, A/B Computers for 3 years in my superstol. It starts up an runs like my 2016 Jeep using no oil or water. I still love my old steam gage Sedan with Lyc 360AIA engine using twice as much gas and a quart of oil every couple hours.
Klaus says
Lycoming TEO-540-A1A TYPE CERTIFICATE DATA SHEET NO. E00009NY is a modern electronic single lever power-plant that recommends Avgas 100VLL.
Lycoming Service Instruction No. 1070S – Specified Fuels for Spark Ignited Gasoline Aircraft Engine Models. S.I. no. 1070S list automotive fuels and qualified engines.
If the FAA would do their job, the FBO’s can sell non-ethanol high grade automotive fuel and 100VLL (Very Low Lead). I guess like every other aviation regulation change, until congress has a vote on changing aviation fuel we just keep slugging along talking about it.
Andrew A says
The experimental community has been using a number of engine alternatives including auto diesel that can easily use Jet fuels with very little modifications. Greater torque and even lower engine rpm than auto engines. Even that is very likely to become a transitional powerplant until electrics take over. And the hybrid solution is also out there that Diamond recently flew using a standard IC engine running generators to charge batteries and run Siemens electric motors. Much quieter than a normal air cooled aircraft engine, smaller displacement running at a slower constant speed. Pipistrel is also looking at a hybrid system using a Rotax engine in their setup. The future could be very interesting indeed. I think the new crop of pilots will demand these new technologies as the electric trainers come into service very soon and the FAA and European agencies see electrics are reliable and can be certified for normal operations.
Miami Mike says
I think the real answer here is electricity.
Electric cars have made great advances in the past few years. The US Military has a 5 by 5 by 5 program for EV batteries (five times the capacity, five times the recharge rate, one fifth the cost) and has unlimited money (ours) to pursue these goals. There is also a tremendous amount of non-military research going on. The automakers are doing this too, VW has been thoroughly stung by dieselgate and is looking towards electric vehicles to clean up their act (pun intended).
Electric airplanes have huge advantages over internal combustion airplanes. No noise, no vibration, no local pollution (and if the power to recharge the batteries comes from hydro/wind/solar, no source pollution either), There’s along list of finicky, undependable, expensive parts which are needed for IC engines and are totally un-needed for electric motors. No mufflers, no fuel pumps, no carburetors, no baffles (air cooled) or heavy, leaky radiators and hoses (water cooled), no fuel tanks, no flammable gasoline to splash around in an accident, and no used oil to dispose of or leak out (or buy new).
Further, no weight and balance issues, a charged battery and a discharged battery weigh the same, no loss of power at altitude (other than loss of propeller efficiency), so no turbo or superchargers needed, no mixture control, no carb heat, no fuel odors or dangerous fuel leaks (want to get nervous in an airplane? “I smell gasoline.”), no warmup or cool down, no shock cooling, instant power NOW when you need it, no reduction gears needed, and best of all, exactly ONE moving part in the motor. A major overhaul consists of changing a pair of large ball bearings, and you’re good for another 10,000 hours or so.
There are only two missing pieces – better batteries, which are coming, and the FAA’s blessing, which may take somewhat longer. EAA will be on the front lines of this, certificated GA manufacturers will have no choice but to follow.
Henry K. COOPER says
Song…..
“I’m gonna jump into
My electric 402!
Don’t know when I will see ya!”
Manny Puerta says
How do I get my 185 to Alaska with an electric motor? Have enough batteries to reduce my useful load to an unusable level? WA state to Ketchikan is 4+30, no wind.
Maybe in some kid’s lifetime, but not mine. Meanwhile, I can take solace knowing that my 185 has not been transformed into a Prius or Tesla. Blasphemy.
Internal combustion in aviation put a lot of food on the table for my family. Hopefully, the sound won’t go away too soon. The IO-520 is doing very well nearing TBO with original cylinders running LOP with a CamGuard cocktail. Electricity beyond electronic ignition and avionics? Phooey.
Miami Mike says
Well, at the moment, you can’t . . .
Technology advances in unexpected ways, sometimes incrementally, sometimes in big jumps. Look at cars – incrementally, automatic spark advance, fuel injection, self-starters, big jumps, automatic transmissions. Very, very few people want to go back to hand cranking their cars, a few of us still like standard shift even though we admit that the newer automatics do a better job than we can (most of the time, anyway).
In 2012, that was six years ago, a long time in the age of the i-thing du jour, I was at the first electric motorcycle grand prix race at the Daytona Speedway. They were doing laps at 186 miles an hour . . . almost silently. The only thing holding them back was the batteries, the race was five laps long. Remember, that was six years ago.
If I could buy a reasonably priced electric airplane with equivalent range, performance and payload to my gasoline powered airplane, I’d do so in an instant. I really don’t care WHAT makes it fly, the point is to be flying. We like gasoline engines because we are used to them. People used to like steam engines for the same reason, but nobody seriously suggests we convert all our gas engines in cars, motorcycles, boats, tractors, airplanes, weed wackers and so on to steam. In twenty years, people will look at gasoline engines and be amazed that people actually rode around in vehicles powered by those things.
I really like my gasoline powered sporty German convertible, but if I could get the same or better performance and utility from powering it with electricity, I would. Same for my gasoline powered airplane, gasoline powered antique motorcycles (which I’d keep anyway) and so on. I could care less what my tractor runs on as long as it works.
Remember, the stone age didn’t end because we ran out of rocks. We found something better. Same for the gasoline age.
Manny Puerta says
All true, but I like my IO-520, Cummins and BMW GS twin. All good sounds. Imagine an AD Skyraider or Mustang with an electric engine. Gaak! Where’s the joy of flight without the sound, adjusting the prop and tweaking the mixture to LOP until all is well and in harmony? Electric has no soul.
Manny Puerta says
Someone sent me this about electric cars. Imagine electric airplanes. We have a long way to go with electric cars, let alone electric airplanes.
We use copper in a lot of things and for a lot of things. The following infographic talks about the copper going into an electric car, but that is only one aspect of having an electric car or a country filled with them. The real big issue will turn out to not be the cars themselves but the power grid needed to support them. Think of all the energy that gasoline and diesel provide and then think about all the gas stations you see in your area. Think of two scenarios, one a car at your house, and the second a car in a city, parked on the street like in Queens NY.
At your house, you just have to run a heavy copper wire to a charging station, the heavier, the faster the charge. In a domestic setting, 8 Gauge wire can deliver 55 Amps at 240 Volts and just the copper alone for four conductors is .2 pounds per foot (four conductors, two hot, one neutral and one ground). This will give you a pretty good charge and say you have to run 50 feet of wire for your circuit thus you are using 10 pounds of copper for your new electric car charging circuit or about 1/8 of the weight of the car’s copper. But what about increasing other aspects of the utility grid to support your car and the hundred million more we will see someday?
Now if you think about electric cars parked on the streets of a major city, how are you going to charge them? Today and for the years I have been alive, the cars ran on gasoline and the owners would fill them at the gas station, park them on the street and drive them as they wished. When the tank was low, they would refill them, but with electric cars, the recharging is going to have to happen at curbside and since parking is random, how is that going to happen? Obviously, the city or utility is going to have to install charging stations all along all the streets and run the cables underground. The charging issue can be solved but the device recognizing the appropriate car and billing the owner, no matter where he or she parks. This is going to be a huge undertaking and the installation is going to be ungodly expensive. Thus the cost of the refilling of the car has changed from private business to government or at least government regulated businesses (utilities) and the cost is going to be high even for a private enterprise, let alone an inefficient governmental agency. Do you hear anybody talking about this when they are selling electric cars?
Copper in a car:
http://www.visualcapitalist.com/how-much-copper-is-in-an-electric-vehicle/
Henry K. Cooper says
I agree. These are good proposals. Leaving 100 LL fuel in place will, or should, allow time for some “real world” testing of 94 UL. And using 94 UL may alleviate burned intake valves in small TCM engines, as well as lead and carbon choking in others.
Using small converted auto engines is a good idea also. Electronic fuel injection and ignition will be an improvement. Trouble is, the fellows in Mobile and Williamsport, at Unison and Bendix, at Facet and other places may soon be looking for jobs.
Rollin Olson says
All very sensible proposals. What’s holding GA back from adopting these and similar proposals, is not the FAA, not costs, but inertia in the pilot community.
Entrepreneurial business will make investments if they perceive that there’s a profitable market for new products. Light Sport airframes and Rotax engines have shown this to be true.
It’s up to us pilots to let go of 1940s-70s technology and accept – even demand – technological improvements.
J. E. Goodbrake says
Great article! I applaud your research and forward looking insights. The REAL problem stopping such progress is the FAA and BIG Bureaucracy. The time it takes and the money it costs to bring even the smallest invention to the market is unacceptable. The regulatory burden has driven up the costs of General Aviation to the point where most pilots cannot even afford a Cessna 172. Lighten the regulatory load, throw the bureaucrats out of the plane and General Aviation will soar once again. Great Article Sir