Originally Posted By: Cujet
Originally Posted By: Surestick
That makes more sense. I'd guess the same could be said for recip powered prop planes (and probably with a slightly higher efficiency "limit" for turboprops (which would benefit more from thrust generated by exhaust gasses)).
Taking a casual look at today's piston powered aircraft, the new 550 cubic inch, twin turbocharged Mooney Acclaim can reach 242Kts top speed, and has an economy cruise of 175Kts. While incredible for a single engine piston 4 seater, it only achieves over 220Kts well into the flight levels.
Yes, some experimental aircraft and warbirds can go much faster. But from a practical standpoint, piston powered aircraft do remain firmly affixed to the bottom of the speed chart. Interestingly, turbocharged piston engines can make rated HP at very high altitudes!
Today's high performance turboprops regularly cruise over 300Kts. The TBM 930 for example reaches 330Kts in normal cruise, and the Piaggio Avanti can reach 400Kts at FL310, but typical long range cruise is 320Kts and as altitudes high as FL410. Impressive, but not "jet" fast.
Our G650ER normal cruise is M.90, or about 515Kts.
Conclusion: Heat is involved in speed.
Disagree, I don't think you've proved heat has anything to do with it, for propellers at least (but that's what the discussion was about initially). Leaving batteries aside put a 280 hp electric motor in the nose of the Mooney in your example, and all else being equal, you should see similar performance.
Jets are a different story since the heated exhaust gasses are such an integral part of the way they produce thrust. The waters get muddier with turbofans but a non-negligible portion of their thrust still comes from exhaust gasses.
Originally Posted By: Surestick
That makes more sense. I'd guess the same could be said for recip powered prop planes (and probably with a slightly higher efficiency "limit" for turboprops (which would benefit more from thrust generated by exhaust gasses)).
Taking a casual look at today's piston powered aircraft, the new 550 cubic inch, twin turbocharged Mooney Acclaim can reach 242Kts top speed, and has an economy cruise of 175Kts. While incredible for a single engine piston 4 seater, it only achieves over 220Kts well into the flight levels.
Yes, some experimental aircraft and warbirds can go much faster. But from a practical standpoint, piston powered aircraft do remain firmly affixed to the bottom of the speed chart. Interestingly, turbocharged piston engines can make rated HP at very high altitudes!
Today's high performance turboprops regularly cruise over 300Kts. The TBM 930 for example reaches 330Kts in normal cruise, and the Piaggio Avanti can reach 400Kts at FL310, but typical long range cruise is 320Kts and as altitudes high as FL410. Impressive, but not "jet" fast.
Our G650ER normal cruise is M.90, or about 515Kts.
Conclusion: Heat is involved in speed.
Disagree, I don't think you've proved heat has anything to do with it, for propellers at least (but that's what the discussion was about initially). Leaving batteries aside put a 280 hp electric motor in the nose of the Mooney in your example, and all else being equal, you should see similar performance.
Jets are a different story since the heated exhaust gasses are such an integral part of the way they produce thrust. The waters get muddier with turbofans but a non-negligible portion of their thrust still comes from exhaust gasses.
