In 1985 when this got kicked off, materials science was talking about making turbine cores from ceramics to allow higher temps. There was some promising prototype data at the time. Not sure whether cost or durability kept ceramics out of mainstream applications.

Maybe but no manufacturer wants to put a Garrett on a new SETP aircraft.






It's called a Garrett TPE Marc.

Mike-

Yes, and No.

The "Yes:" I agree with your numerical assessment on your own aircraft's propulsion system. 27% isn't awesome as a raw number, but you're also not doing too poorly!

The "No:" You're saying "I'm 27% efficient" and then implying you should be closer to 70/80/90+%. That's not remotely reasonable IMHO, as you need to look at that Carnot equation you quoted. If the temperature of heat rejection is ~600 Klevin (~330 Celsius) then you would have to have heat addition at ~1500 Kelvin (~1200 Celsius) just to reach 60% efficiency of the PERFECT engine. Throw in there irreversibilities (not present in Carnot, but present in real-life) and you're easily down in the 50% range.

BTW, my swag of 600K for heat rejection seems like a low temp to me. It's probably higher, so the engine would need to withstand 1600-2000 Kelvin on the hot side. As humans we've been working with metals/materials for thousands of years. If it was so easy to develop a turbine wheel that could withstand an additional 200 degrees C (or 200K, same thing) we would have done it already.

Again with my example: If 60% is the upper limit of the power cycle, and the engine has a propulsive efficiency of 95% (again, swag) then the Turbofan itself is around 57% efficient in terms of turning heat into thrust. If P&W was at 40%, and is now at 46.4% (up +16% from the 40% before) they've just closed a "gap" of 38% from where they were before (40%) and a reasonable upper limit of 57%.

I think your wire delay example makes my point for me. If those "little" (1-3%?) improvements in delays make the difference between their chips being OK and being highly competitive in the market, then who cares how much they spent and in how long? As Ricky Bobby's dad famously said "If you're not first, you're last." It's a stupid saying, unless being runner-up gets you almost no return/business/benefit. Those "little" gains got them the competitive edge they needed, whether through besting a competitor directly or by opening up other technological possibilities with the lower delays, then they were worth it. *Note: E.E./Comp Sci is not my wheelhouse, I'm just trying to work with your example.*

All that being said, I'm not trying to turn this into a cage match. I'd *also* like to see better performance and "sexier" breakthroughs . However, I just don't think we should totally dismiss this improvement. Sure, the P&W GTF might not make Vlad Putin crap himself with fear, or cause ISIS to close their twitter account. However, when you look at the science, it's actually pretty impressive (and a bargain @ *only* $10-Billion!)

Kestrel was. Project stalled.

TPE331 not as well suited to singles due to straight back exhaust.

I'm not aware of many *new* SETP projects to being with. When was the last one certified? 20+ years ago with the PC-12?

Mike C.

I'm not aware of any twin engine turbo prop projects either.

You could say the SETP and TETP markets are saturated. Pilatus sells 50 planes a year. Is that market someone else should try and get into?

That said, I don't really see why Pilatus built the PC24. The jet market is ridiculously saturated.

Not quite, for the 737 Max they kept the main gear the same length but raised the nose gear something like 6" or 7".

I don't know anything about the A320 NEO except it looks better with the bigger jugs on those long skinny legs.

I felt the need to re-read that 10 times.

I feel better, and I don't know why.

Thank you.

So, less pollution and quieter. This is what we call innovation and technology in 2015?

45 years ago we had a supersonic transport aircraft flying passengers, we had the SR-71 running around at Mach 3 and 80,000 feet, we had spacecraft capable of landing on the moon, we had the first business jets with climb performance better than their modern competitors ...

I'm sorry, but this is NOT groundbreaking or innovative. This just furthers the proof that we have become a society of spineless pansies.[/quote]

I felt the need to re-read that 10 times.

I feel better, and I don't know why.

Thank you.[/quote]
We also had pilots that could ace NDB approaches in icing conditions without synthetic vision and FLIR.... and not even an RMI in most cases.