Wow!
A Carbon Cub is right about the same size as a Piper Super Cub. The lightness comes from the use of composites.
it is not a free turbine.
"If you want a turbine, pal, you gotta pay for it."
I didn’t say it was a free turbine. I was responding to another poster that said it was a free turbine and then specifically referred to how fast those can spool which is incorrect.
Whoosh…
The sound of that joke going overhead.
I got that part. Still don’t get the joke. Whoosh
Turbotech is probably one of the leading developers of these new micro-turbines and is backed by Safran. However, micro-turbines have been around for decades but were notoriously not fuel efficient until Turbotech came up with their version. There are also a number of other micro-turbo developers out there, but they are concentrating more on turbo-generators for hybrid propulsion units in the e-aircraft industry vs installing on small GA airplanes. However, I think given where the industry is going, you may see more hybrid electrical retrofit kits for small airplanes in the future than direct turbine retrofits as this technology matures at a fairly fast rate.
Thanks for the background, this is exciting technology, and I look forward to seeing how it matures.
Nitpick. Regenerative turbines have been around for many decades.
True. But those were very heavy. Turbotech found a way to dramatically lighten the regenerative aspect which made it useable for aircraft applications. Regardless, there is zero comparison on several levels between recip and turbines in a direct drive scenario. Now use a that Turbotech for electrical power generation in a hybrid propulsion setup and an avgas recip comes nowhere close to those efficiency numbers. And Turbotechs main priority is on the hybrid side with these direct drive installations simply an attempt to expand their market.
That's the best summary on this product I've seen. Yeah, they will sell a bunch of planes to folks that have way too much money and want the latest toy on the market. No cub pilots making a living with their planes will buy one, and they won't appear in the average pilot's hangar. I'm assuming the tubotech CFO and marketing director looked at the potential sales and decided there's enough of a niche market to go for it. I'll be happy to look at them when they land at the same airport I'm parked at, but I will never be a customer. I just don't have the disposable income to make it work for me. Besides, my mission calls for a plane that can easily haul my bicycle and my camping gear and get into backcountry strips. The turbine cub isn't that plane.
No part of that statement is correct. A direct drive turbine converts expansion energy to rotating energy with energy loss in the form of heat. A recip does the same but a little more efficiently. A Hybrid converts the rotation to electricity wasting more on heat, then back to rotation, again loosing energy to heat. In an average car around town it works because energy is recovered during deceleration. A direct drive car will get better economy than an equal weight hybrid at the same highway speed.
Except the current flying aircraft with hybrid-electrical propulsion don’t agree with that statement. So much so, most legacy turbine OEMs are designing/building their own versions of turbo-generators to power the next generation of eVTOL, eSTOLs, and eCTOLs. For example, Safran’s TG600 turbo-gen is one such new, purpose-built hybrid unit and will be installed in the production version of the Electra EL-9, 9 pax, eSTOL aircraft. Plus the actual data I’ve seen of their ops does not match your narrative at all. Is what it is.
Toyota announced a few years ago the Renaissance engines; the basic premise is an engine tuned for a single speed connected as a range extender (e.g. serial hybrid) is more efficient.
This. And increasing the combustion cycle temps also lead better efficiency which is what the regenerative systems do. Most turbogenerators, like APUs in airliners, even bypass the idle stage and run at a governed power level with minimal variation. So when efficiencies are compared, the average ICE runs at about 20-40% efficiency, turbo-gens at 50%, and on the electric side a typical e-motor will be greater than 90% efficiency. And with the new turbo-gens like the TG600 above which will offer a 15% increase in fuel economy plus the new e-motors being closer to 97% it will be interesting how all that comes togather in the near future.
