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I guess it depends. I understand some ultralights and new airplanes may be efficient. But it is my understanding that a Cessna 172 lycoming is basically 50-70 y

I guess it depends. I understand some ultralights and new airplanes may be efficient. But it is my understanding that a Cessna 172 lycoming is basically 50-70 years old, depending on how you count, and horribly inefficient, and completely prevalent. Faa certification for new engines is such that innovation is stifled. I mean it took the industry what, 3-4 decades and counting, to phase out leaded fuel which we all agree is God awful :-0

sokoloff 4y ago
The C172 (most common small airplane) has a Lycoming 4-cylinder engine of various sizes throughout the years. A representative engine, the O-320, is around 89% as efficient as traditional (non-hybrid, non-Atkinson) ICE automobile at turning gasoline into productive work. I don’t view an 11% spread as “horribly inefficient” given the need for many redundant systems, air-cooling, high diameter pistons, and relatively low RPM. 0-https://michaelsoroka.com/2014/03/26/are-airplane-engines-inefficient/ https://michaelsoroka.com/2014/03/26/are-airplane-engines-in...
- nimish 4y ago
  They lack a bunch of emissions control equipment like fuel injection, catalytic converters, and the like. They are 60's or maybe 80's car engines that are still made since nobody in GA wants to pay for better ones.
  - laverya 4y ago
    > since nobody in GA wants to pay for better ones. Since nobody wants to pay to certify better ones. The engine in a Cessna 172 is going to run you $20-40k (20k rebuilt, 40k new afaict - check out [0]) - far more expensive than an automobile engine with 'equivalent' performance. The difference is that the Lycoming is certified by the FAA for use with your airframe. (And it'll work in whatever conditions you care to name, and with a car engine that's only a 'probably') 0: https://www.coronaengines.com/In-Stock https://www.coronaengines.com/In-Stock
  - jcoby 4y ago
    > They lack a bunch of emissions control equipment like fuel injection, catalytic converters, and the like. Yeah unfortunately the weight and size of those systems is prohibitive for most light aircraft. Plus catalytic converters and oxygen sensors for closed loop efi can’t be used with leaded fuel. > They are 60's or maybe 80's car engines that are still made since nobody in GA wants to pay for better ones. The Lycoming and continental engines in most of the fleet were certified in the early 50s. A few were in the early 60s. That means they were designed in the 40s and 50s!
avalys 4y ago
That's my point, the Lycoming (while an old design) is not all that inefficient. A Cessna 172 burns about 8 gallons per hour and travels at 125 knots, or about 140 mph. That's the equivalent of about 18 mpg. There's been an enormous improvement in automobile engine efficiency in the past 30 years, and most of that has come from optimizing engines and transmissions to minimize their fuel consumption under light load, while still giving them enough peak power capacity to accelerate quickly, tow a heavy load up a hill when needed, etc. In comparison, an aircraft engine spends very little time "idling" and sees very little change in load over the course of a flight. It just runs at a fixed speed and power setting for most of the time. There isn't that much to optimize or improve.
- maximilianburke 4y ago
  There's tons to optimize! Timing is a big one; magento fired engines have fixed timing. The engines can't remove or add timing to get more power. Fuel ratios are determined by the pilot with current Lycoming and Continentals. Why should the pilot need to worry about this? EFI has been around for 40 years now and would help decrease the cognitive load on the pilot. Like, how many engines have cooked valves because the pilot (or student) forgot to richen the mixture before descending? Cooling is a huge one. There are a few liquid cooled aircraft engines and they just make everything easier. The engines are more reliable, and it also removes a carbon monoxide poisoning risk due to corrosion in the exhaust cuff. Yeah, a Cessna can get better fuel economy than a car traveling at 140mph but it could be _so much better_ than what it is. And not just better fuel economy, but better all around experience for the pilots (lower cognitive load), and owners (lower cost of living, more reliable engines).
  - sokoloff 4y ago
    Many racecars and boats also run fixed timing. Variable timing is needed when the load is variable. If the load is constant, the timing can be fixed. Modern engine monitors have given us more insight than ever into engine operation and I don’t find the engine management particularly taxing. After initial takeoff, I’m likely to set the power (throttle, RPM, and fuel mixture) at 1000’ above the ground and not touch it again for 4 hours (when it’s time to transition to landing).

sokoloff 4y ago

The C172 (most common small airplane) has a Lycoming 4-cylinder engine of various sizes throughout the years. A representative engine, the O-320, is around 89% as efficient as traditional (non-hybrid, non-Atkinson) ICE automobile at turning gasoline into productive work. I don’t view an 11% spread as “horribly inefficient” given the need for many redundant systems, air-cooling, high diameter pistons, and relatively low RPM. 0-https://michaelsoroka.com/2014/03/26/are-airplane-engines-inefficient/ https://michaelsoroka.com/2014/03/26/are-airplane-engines-in...

nimish 4y ago
They lack a bunch of emissions control equipment like fuel injection, catalytic converters, and the like. They are 60's or maybe 80's car engines that are still made since nobody in GA wants to pay for better ones.
- laverya 4y ago
  > since nobody in GA wants to pay for better ones. Since nobody wants to pay to certify better ones. The engine in a Cessna 172 is going to run you $20-40k (20k rebuilt, 40k new afaict - check out [0]) - far more expensive than an automobile engine with 'equivalent' performance. The difference is that the Lycoming is certified by the FAA for use with your airframe. (And it'll work in whatever conditions you care to name, and with a car engine that's only a 'probably') 0: https://www.coronaengines.com/In-Stock https://www.coronaengines.com/In-Stock
- jcoby 4y ago
  > They lack a bunch of emissions control equipment like fuel injection, catalytic converters, and the like. Yeah unfortunately the weight and size of those systems is prohibitive for most light aircraft. Plus catalytic converters and oxygen sensors for closed loop efi can’t be used with leaded fuel. > They are 60's or maybe 80's car engines that are still made since nobody in GA wants to pay for better ones. The Lycoming and continental engines in most of the fleet were certified in the early 50s. A few were in the early 60s. That means they were designed in the 40s and 50s!

avalys 4y ago

That's my point, the Lycoming (while an old design) is not all that inefficient. A Cessna 172 burns about 8 gallons per hour and travels at 125 knots, or about 140 mph. That's the equivalent of about 18 mpg. There's been an enormous improvement in automobile engine efficiency in the past 30 years, and most of that has come from optimizing engines and transmissions to minimize their fuel consumption under light load, while still giving them enough peak power capacity to accelerate quickly, tow a heavy load up a hill when needed, etc. In comparison, an aircraft engine spends very little time "idling" and sees very little change in load over the course of a flight. It just runs at a fixed speed and power setting for most of the time. There isn't that much to optimize or improve.

maximilianburke 4y ago
There's tons to optimize! Timing is a big one; magento fired engines have fixed timing. The engines can't remove or add timing to get more power. Fuel ratios are determined by the pilot with current Lycoming and Continentals. Why should the pilot need to worry about this? EFI has been around for 40 years now and would help decrease the cognitive load on the pilot. Like, how many engines have cooked valves because the pilot (or student) forgot to richen the mixture before descending? Cooling is a huge one. There are a few liquid cooled aircraft engines and they just make everything easier. The engines are more reliable, and it also removes a carbon monoxide poisoning risk due to corrosion in the exhaust cuff. Yeah, a Cessna can get better fuel economy than a car traveling at 140mph but it could be _so much better_ than what it is. And not just better fuel economy, but better all around experience for the pilots (lower cognitive load), and owners (lower cost of living, more reliable engines).
- sokoloff 4y ago
  Many racecars and boats also run fixed timing. Variable timing is needed when the load is variable. If the load is constant, the timing can be fixed. Modern engine monitors have given us more insight than ever into engine operation and I don’t find the engine management particularly taxing. After initial takeoff, I’m likely to set the power (throttle, RPM, and fuel mixture) at 1000’ above the ground and not touch it again for 4 hours (when it’s time to transition to landing).