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Lots of innovation has happened in aircraft electronics. The powerplant? Not so much. Most light aircraft engine designs are four or more decades old, and the o

Lots of innovation has happened in aircraft electronics. The powerplant? Not so much. Most light aircraft engine designs are four or more decades old, and the only ones cheap enough for a moderately-priced aircraft have carburetors. I don't think you can even buy a car these days with a carburetor, but with airplanes they're still standard, even though fuel injection makes a lot more sense in an airplane than in a car. You can get airplanes with fuel-injected engines, but a fuel-injected Lycoming IO-390 engine (like you'd find in a Cirrus) will cost about $27,000. Used. Just for the engine. You can get a decent car for $27,000, and it will absolutely have a fuel-injected engine. Likely a turbocharger as well. And the car's engine will produce a lot more horsepower. Oh and you'll have to fuel the airplane with avgas which costs $5/gallon and contains lead, and you have to wonder WTF?? There's no technical reason aircraft engines cannot be turbocharged, fuel-injected, fueled with regular unleaded gas, and cheap. Aircraft engines should have followed the innovation advancements that have happened in car engines, but they haven't. This is probably because of regulation, monopoly power, liability, and a host of other reasons, but as an engineer I find the situation ridiculous.

NickNameNick 6y ago
Car horsepower and airplane horsepower are very different things. A car engine has to be able to maintain peak power output for a few seconds while accelerating. maybe a few seconds, unless you're towing a load up a hill or something. On level ground you're using a small but variable amount of your available power. An airplane engine has to maintain peak power for the entire climb-out, and a substantial fraction of that for cruising for hours at a time.
- userbinator 6y ago
  unless you're towing a load up a hill or something This reminds me of how a lot of people are surprised when they find out the engine of a typical semi-truck has "only" a few hundred HP but several times the displacement of a passenger car engine rated at almost the same power. The car engine will wear out quickly at continuous full load, whereas the semi engine is designed to run at full load continuously. Ditto for engines driving generators and pumps --- full load is normal load.
wpearse 6y ago
US$5/gallon is about the same price as our vanilla automobile juice here in NZ. We pick up avgas (half the price) from the small airport near us if we’re doing strictly off-road activities in our vehicles (no fuel tax).
- dreamcompiler 6y ago
  Interesting. I had assumed avgas was more expensive than auto gas everywhere but I guess not.
  - adwww 6y ago
    It might be before tax, but in most places on-road vehicle fuel is taxed significantly higher than avgas.
- LilBytes 6y ago
  Fuel in NZ is $5 NZD? Has Covid had an impact on that local price or is that standard? It's Less than $1.50 AUD across the ditch at the moment. And that's a bad day.
  - solraph 6y ago
    Per gallon. $1.30 / L => $5.85 / gallon. Petrol is/was always more expensive in NZ though, around ~70c/L from memory. On the flip side, registration and insurance is much cheaper.
    - LilBytes 6y ago
      Ah, thanks! I missed the measurement (per galling to a litre). That makes more sense.
- rimliu 6y ago
  And cheaper than car gas here in Europe (Lithuania).
- golem14 6y ago
Stevvo 6y ago
There's no technical reason light aircraft engines can't be a heck of a lot better than turbocharged, fuel-injected pistons. They could all be cheap turbojets designed for low altitude flight burning regular diesel at 10gph going 300 Knots, with far higher reliability than any piston. Unfortunately for the reasons you mentioned, and the myth that turbines can't be efficient at low altitudes, nobody is going to develop that engine.
- dreamcompiler 6y ago
  Eclipse tried it and went bankrupt. But it was a nice idea. https://en.m.wikipedia.org/wiki/Eclipse_400 https://en.m.wikipedia.org/wiki/Eclipse_400
s1dev 6y ago
The problem with the 100LL phase-out is that you have over 70 years of engines and fuel systems designed to work with leaded fuel. In order to complete the phase-out you either need to: force people to put a new $30K+ engine into a <$50K plane, totally replace the fuel system, and get a supplemental type certificate or: Require that the new fuel is a drop in replacement. One would have to show that the new fuel is 100% compatible with 100LL without modifications to the aircraft. The FAA has been attempting the second route for some years, but to date has not been terribly successful. The first route has been done successfully in other regions such as the EU, but I would suspect there is far less legacy general aviation aircraft. I personally look forward to the mainstream introduction of diesel engines into the US market that are able to run on Jet-A
- manquer 6y ago
  You have a sensible third option which is how automotive changed for the most part. Grandfather in current planes and mandate new models to use new fuel only. Over time, perhaps lot longer than cars(planes do have longer life) you will have changed all of them. Had they started it in 80's and 90's same time as auto-mobiles, most planes would have changed by now. Every industry faces the same challenges to transform technology, they are able to move forward without as much difficulty as aviation ?
  - TylerE 6y ago
    No they wouldn't. You're underestimating the age of the fleet. The average GA aircraft is 50 years old, and that is likely to increase in the near-medium term as production of GA aircraft is practically zero. Source: https://www.ainonline.com/aviation-news/business-aviation/2007-01-10/faa-examine-aging-ga-aircraft-fleet#:~:text=The%20General%20Aviation%20Manufacturers%20Association,2020%2C%E2%80%9D%20noted%20the%20FAA https://www.ainonline.com/aviation-news/business-aviation/20.... (Cirrus, mentioned above, produces about 300 aircraft a year - compare to the 100,000+ Ceessnas on GA fields, almost all of which are over 40 years old.
    - manquer 6y ago
drewm1980 6y ago
Wow, hearing that rich people are still allowed to dump lead into the atmosphere above our heads just ruined my morning. What things of non-entertainment value would we loose if we just banned leaded fuel overnight? Are crop dusters burning lead while spraying pesticides over our food crops?
- tjohns 6y ago
  You don't need to be rich to fly. You can buy a older used aircraft for the cost of a nice car. Sometimes cheaper. (Note: Not the Cirrus they're talking about upthread.) They're working on replacing leaded fuel. The challenge is mostly regulatory, since they won't certify any of the replacements until they're sure it's 100% safe. It's still a work in progress. As for what you'd lose: Search and rescue, medical transport (both commercial and volunteer), transport of blood samples for lab testing, high resolution aerial photography on your smartphone, powerline inspection to prevent forest fires, crop dusting. I could go on...
  - NikkiA 6y ago
    Search and rescue is almost soley helicopter traffic, and very rarely requires leaded fuel (a turbine doesn't need leaded, it can run on it, but it'll run just fine on unleaded too). The number of places still using non-turbine helicopters for anything other than training and very light sightseeing is very small, probably close to 0% worldwide. Same is true of Medical Transport except possibly for Australia where light aircraft are used more frequently than turbine helicopters. Same for powerline inspection, although there could be a couple of companies using Robinsons somewhere I guess.
    - dreamcompiler 6y ago
      Search and rescue in the USA is mostly done by the Civil Air Patrol, which almost solely uses fixed-wing aircraft.
- tr352 6y ago
  Doing so would bankrupt pretty much the entire general aviation industry. Also, training new pilots would become impossible.
cheerlessbog 6y ago
How do carburetors work when inverting the plane?
- looping__lui 6y ago
  Most GA planes are only permitted to fly “positive g” for reasons like this...
- bboreham 6y ago
  Solutions to this problem were developed in the early 1940s: German fighters had fuel-injected engines. https://en.wikipedia.org/wiki/Miss_Shilling%27s_orifice https://en.wikipedia.org/wiki/Miss_Shilling%27s_orifice https://en.wikipedia.org/wiki/Pressure_carburetor https://en.wikipedia.org/wiki/Pressure_carburetor

NickNameNick 6y ago

Car horsepower and airplane horsepower are very different things. A car engine has to be able to maintain peak power output for a few seconds while accelerating. maybe a few seconds, unless you're towing a load up a hill or something. On level ground you're using a small but variable amount of your available power. An airplane engine has to maintain peak power for the entire climb-out, and a substantial fraction of that for cruising for hours at a time.

userbinator 6y ago
unless you're towing a load up a hill or something This reminds me of how a lot of people are surprised when they find out the engine of a typical semi-truck has "only" a few hundred HP but several times the displacement of a passenger car engine rated at almost the same power. The car engine will wear out quickly at continuous full load, whereas the semi engine is designed to run at full load continuously. Ditto for engines driving generators and pumps --- full load is normal load.

wpearse 6y ago

US$5/gallon is about the same price as our vanilla automobile juice here in NZ. We pick up avgas (half the price) from the small airport near us if we’re doing strictly off-road activities in our vehicles (no fuel tax).

dreamcompiler 6y ago
Interesting. I had assumed avgas was more expensive than auto gas everywhere but I guess not.
- adwww 6y ago
  It might be before tax, but in most places on-road vehicle fuel is taxed significantly higher than avgas.
LilBytes 6y ago
Fuel in NZ is $5 NZD? Has Covid had an impact on that local price or is that standard? It's Less than $1.50 AUD across the ditch at the moment. And that's a bad day.
- solraph 6y ago
  Per gallon. $1.30 / L => $5.85 / gallon. Petrol is/was always more expensive in NZ though, around ~70c/L from memory. On the flip side, registration and insurance is much cheaper.
  - LilBytes 6y ago
    Ah, thanks! I missed the measurement (per galling to a litre). That makes more sense.
rimliu 6y ago
And cheaper than car gas here in Europe (Lithuania).
golem14 6y ago

Stevvo 6y ago

There's no technical reason light aircraft engines can't be a heck of a lot better than turbocharged, fuel-injected pistons. They could all be cheap turbojets designed for low altitude flight burning regular diesel at 10gph going 300 Knots, with far higher reliability than any piston. Unfortunately for the reasons you mentioned, and the myth that turbines can't be efficient at low altitudes, nobody is going to develop that engine.

dreamcompiler 6y ago
Eclipse tried it and went bankrupt. But it was a nice idea. https://en.m.wikipedia.org/wiki/Eclipse_400 https://en.m.wikipedia.org/wiki/Eclipse_400

s1dev 6y ago

The problem with the 100LL phase-out is that you have over 70 years of engines and fuel systems designed to work with leaded fuel. In order to complete the phase-out you either need to: force people to put a new $30K+ engine into a <$50K plane, totally replace the fuel system, and get a supplemental type certificate or: Require that the new fuel is a drop in replacement. One would have to show that the new fuel is 100% compatible with 100LL without modifications to the aircraft. The FAA has been attempting the second route for some years, but to date has not been terribly successful. The first route has been done successfully in other regions such as the EU, but I would suspect there is far less legacy general aviation aircraft. I personally look forward to the mainstream introduction of diesel engines into the US market that are able to run on Jet-A

manquer 6y ago
You have a sensible third option which is how automotive changed for the most part. Grandfather in current planes and mandate new models to use new fuel only. Over time, perhaps lot longer than cars(planes do have longer life) you will have changed all of them. Had they started it in 80's and 90's same time as auto-mobiles, most planes would have changed by now. Every industry faces the same challenges to transform technology, they are able to move forward without as much difficulty as aviation ?
- TylerE 6y ago
  No they wouldn't. You're underestimating the age of the fleet. The average GA aircraft is 50 years old, and that is likely to increase in the near-medium term as production of GA aircraft is practically zero. Source: https://www.ainonline.com/aviation-news/business-aviation/2007-01-10/faa-examine-aging-ga-aircraft-fleet#:~:text=The%20General%20Aviation%20Manufacturers%20Association,2020%2C%E2%80%9D%20noted%20the%20FAA https://www.ainonline.com/aviation-news/business-aviation/20.... (Cirrus, mentioned above, produces about 300 aircraft a year - compare to the 100,000+ Ceessnas on GA fields, almost all of which are over 40 years old.
  - manquer 6y ago

drewm1980 6y ago

Wow, hearing that rich people are still allowed to dump lead into the atmosphere above our heads just ruined my morning. What things of non-entertainment value would we loose if we just banned leaded fuel overnight? Are crop dusters burning lead while spraying pesticides over our food crops?

tjohns 6y ago
You don't need to be rich to fly. You can buy a older used aircraft for the cost of a nice car. Sometimes cheaper. (Note: Not the Cirrus they're talking about upthread.) They're working on replacing leaded fuel. The challenge is mostly regulatory, since they won't certify any of the replacements until they're sure it's 100% safe. It's still a work in progress. As for what you'd lose: Search and rescue, medical transport (both commercial and volunteer), transport of blood samples for lab testing, high resolution aerial photography on your smartphone, powerline inspection to prevent forest fires, crop dusting. I could go on...
- NikkiA 6y ago
  Search and rescue is almost soley helicopter traffic, and very rarely requires leaded fuel (a turbine doesn't need leaded, it can run on it, but it'll run just fine on unleaded too). The number of places still using non-turbine helicopters for anything other than training and very light sightseeing is very small, probably close to 0% worldwide. Same is true of Medical Transport except possibly for Australia where light aircraft are used more frequently than turbine helicopters. Same for powerline inspection, although there could be a couple of companies using Robinsons somewhere I guess.
  - dreamcompiler 6y ago
    Search and rescue in the USA is mostly done by the Civil Air Patrol, which almost solely uses fixed-wing aircraft.
tr352 6y ago
Doing so would bankrupt pretty much the entire general aviation industry. Also, training new pilots would become impossible.

cheerlessbog 6y ago

How do carburetors work when inverting the plane?

looping__lui 6y ago
Most GA planes are only permitted to fly “positive g” for reasons like this...
bboreham 6y ago
Solutions to this problem were developed in the early 1940s: German fighters had fuel-injected engines. https://en.wikipedia.org/wiki/Miss_Shilling%27s_orifice https://en.wikipedia.org/wiki/Miss_Shilling%27s_orifice https://en.wikipedia.org/wiki/Pressure_carburetor https://en.wikipedia.org/wiki/Pressure_carburetor