Comment by phillc73 | Hacker News Reader

Comment by phillc73 | Hacker News Reader

Parent Full thread

And that is the problem. These old Avgas burning carburetored dinosaurs are hugely inefficient. However, the effort required to certify new engine designs for light aviation is prohibitive, because they're never going to sell in numbers high enough to recoup the development/certification costs.

Diamond Aircraft in Austria are producing single and twin engine light aeroplanes with diesel engines, oriignally based on an automotive design. However, they've been through a bankruptcy event and are frankly lucky to still be manufacturing.

There are options to retro-fit diesel engines to the single Cessna range, but if I recall correctly, a deal for a new factory build with that option fell through a couple of years ago. Buy a new Cessna 182, still fill it with Avgas.

Aircraft piston engine efficiency is actually quite similar (measured in brake specific fuel consumption) to modern auto engines. The Lycoming O-320 in a Cessna 172 burns 280 g/kWh. Modern auto engines like the EcoBoost burn not much less -- ~250 g/kWh. See https://en.wikipedia.org/wiki/Brake_specific_fuel_consumptio....

Moreover, aircraft engines like the O-320 can run for hours at continuous max power output. Good luck doing that with a car engine.

Car engines absolutely demolish aircraft engines on emissions, though. They have O2 sensors, computer-controlled ignition systems, and catalytic converters, whereas aircraft piston engines have fixed ignition timing and burn extremely rich of peak (meaning massive emissions) at takeoff power. And on top of that, while little engines like the O-320 can burn ethanol-free autogas, the big piston engines like a Continental IO-550 require leaded fuel, adding another pollutant to the mix.

The diesel engines that Diamond sells now (from Austro Engine) are unrelated to the the old troubled Thielert diesel engines they initially used, IIRC.

And the Thielert Centurion diesels were based on Mercedes Benz car diesels, by the way!

Yes, but I'm pretty sure at least some of them are based on automotive diesel technology, such as those in the DA62

https://en.wikipedia.org/wiki/Diamond_DA62

https://en.wikipedia.org/wiki/Austro_Engine_E4

Reply on news.ycombinator.com