4 ms·

Why are diesels so uncommon among piston aircraft, it's almost always avgas? Is it just "because that's how it's always been" or are there actual engineering re

by kortex 3y ago

Why are diesels so uncommon among piston aircraft, it's almost always avgas? Is it just "because that's how it's always been" or are there actual engineering reasons diesel are inferior? Cursory searching suggests it's mostly this inertia. It'd be especially useful if they could run on regular jet fuel, then turboprops/jets and pistons could use the same fuel infra.

russdill 3y ago
There's a number of difficult engineering tradeoffs. Engines that can run on diesel typically need to be heavier.
PumpkinSpice 3y ago
Diesel engines operate at higher pressures and must be considerably heavier to achieve the same performance & efficiency. Not a huge issue for ships, trains, or cars. Huge issue for flying stuff.
jacquesm 3y ago
Power to weight ratio. Diesel engines tend to be cast iron rather than aluminum.
jabl 3y ago
As others mentioned, diesels tend to have worse performance/weight due to heavier construction. In the early days of aviation (like 1930's or such) there was some effort to introduce diesels for long-range aircraft, the idea being that the heavier powerplant would be offset by the lower required fuel load due to better fuel economy. But they weren't successful. More recently there has been something of a renewed interest in aviation diesel engines, the motivation being they can run on Jet A-1 in addition to diesel fuel. Jet A-1 is what jet (and turboprop) aircraft use, and is available at basically every airport worldwide, is much cheaper than avgas, and no risk of being phased out like the leaded avgas being discussed in this article.
papa-whisky 3y ago
As the sibling comments have pointed out, power-to-weight is the main reason, but it doesn't make diesel engines completely unfeasible for light aircraft. Diamond Aircraft have had success selling planes with diesel engines recently, and even started a subsidiary company to manufacture them: https://en.wikipedia.org/wiki/Austro_Engine https://en.wikipedia.org/wiki/Austro_Engine
mchid 3y ago
People in the united states don't like diesel. It's mainly a cultural thing.

by kortex 3y ago

russdill 3y ago

There's a number of difficult engineering tradeoffs. Engines that can run on diesel typically need to be heavier.

PumpkinSpice 3y ago

Diesel engines operate at higher pressures and must be considerably heavier to achieve the same performance & efficiency. Not a huge issue for ships, trains, or cars. Huge issue for flying stuff.

jacquesm 3y ago

Power to weight ratio. Diesel engines tend to be cast iron rather than aluminum.

jabl 3y ago

As others mentioned, diesels tend to have worse performance/weight due to heavier construction. In the early days of aviation (like 1930's or such) there was some effort to introduce diesels for long-range aircraft, the idea being that the heavier powerplant would be offset by the lower required fuel load due to better fuel economy. But they weren't successful. More recently there has been something of a renewed interest in aviation diesel engines, the motivation being they can run on Jet A-1 in addition to diesel fuel. Jet A-1 is what jet (and turboprop) aircraft use, and is available at basically every airport worldwide, is much cheaper than avgas, and no risk of being phased out like the leaded avgas being discussed in this article.

papa-whisky 3y ago

As the sibling comments have pointed out, power-to-weight is the main reason, but it doesn't make diesel engines completely unfeasible for light aircraft. Diamond Aircraft have had success selling planes with diesel engines recently, and even started a subsidiary company to manufacture them: https://en.wikipedia.org/wiki/Austro_Engine https://en.wikipedia.org/wiki/Austro_Engine

mchid 3y ago

People in the united states don't like diesel. It's mainly a cultural thing.