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> Agreed, but sadly it's still a niche fuel. ... I think that unless a large number of GA airplanes can run on true automotive gas (which means gasohol now) in

by jabl 4y ago

> Agreed, but sadly it's still a niche fuel. ... I think that unless a large number of GA airplanes can run on true automotive gas (which means gasohol now) in the near future, GA is doomed. There are several problems with gasohol outside the core engine, from compatibility with fuel systems (bladders etc.), to phase separation, to vapor lock, to hygroscopicity. I'm sure that can be designed around, but it's not a drop-in replacement in planes designed for avgas. If you want an abundant and affordable fuel, in the aviation world that's Jet A(-1). There's some limited success with Jet A burning diesel engines for the GA market (Thielert (or whatever they're called today) and Austro mainly). Personally I think it would be cool if turbines suitable for GA would be developed. Currently turbines cost an arm and a leg, but I think partially that is an effect of development focused on power/weight and fuel efficiency, cost be damned. That might suit commercial and military use, but not GA. And yes, turbines don't scale down very well either. Still, a turbine that would have an upfront cost competitive with current GA engines would be very attractive, even if it would come at a cost in fuel efficiency. That would be, I think, more than compensated by the power/weight and safety advantages, as well as fuel availability and affordability. I think there are a couple of companies working in this space (TurbAero and Turbotech that I'm aware of, maybe others as well), we'll see if any of them ever come to fruition.

p_l 4y ago
A big problem with turbines is overhauls and how they are calculated. For piston engines, overhaul time is calculated from amount of hours operated. For turbine engines it is calculated from amount of hours and amount of start-stop cycles, whichever is reached first. And in GA, you have short flights and many cycles, which results in overhauls being much more common and expensive.
NonNefarious 4y ago
Yep, I wouldn't expect the transition to have occurred overnight. But after several decades of experience in automotive applications, I'd think the GA fleet could have been adapted by now if the industry had taken it seriously. I also realize that the regulatory regime has stifled progress. It seems a bit better now, but it may be too late.

by jabl 4y ago

p_l 4y ago

A big problem with turbines is overhauls and how they are calculated. For piston engines, overhaul time is calculated from amount of hours operated. For turbine engines it is calculated from amount of hours and amount of start-stop cycles, whichever is reached first. And in GA, you have short flights and many cycles, which results in overhauls being much more common and expensive.

NonNefarious 4y ago

Yep, I wouldn't expect the transition to have occurred overnight. But after several decades of experience in automotive applications, I'd think the GA fleet could have been adapted by now if the industry had taken it seriously. I also realize that the regulatory regime has stifled progress. It seems a bit better now, but it may be too late.