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on Dec 29, 2017

Re CROR: How about CRoP - Counter-Rotating Propellers (a now "ancient" term) as an alternative acronym?

on Dec 30, 2017

At one time, i owned enough year-old 'cell phones' to cover your entire house 2 feet deep. 'Fashion' drives every industry (and politics), not practical considerations:(
GE and P&W built 'open rotors' for three or four decades, no takers.
Enjoy your tax bill.

on Dec 31, 2017

Rolls-Royce, Allison, P&W and GE all developed contra-rotating open rotors in the 1980’s. The Allison (now Rolls-Royce) and GE engines actually flew. They demonstrated fuel savings of more than 15% at a time when oil had reached $30 a barrel and everyone thought the world was going to end. BUT they were incredibly noisy.

In the Clean Sky programme, both Rolls-Royce and Safran worked on novel Open Rotor designs, driven now by environmental considerations. They demonstrated the same 15%+ fuel saving, even against the latest enclosed fan technology, BUT with ability to meet latest airport noise restrictions with a 10dB margin.
Tax payers’ and Company money well-spent!
Ric Parker - Chairman Clean Sky

on Jan 1, 2018

The spent part is what comes out of the core.

Open rotors themselves cannot be asses in a vacuum.

In short it has to be mounted and it has to be based on the issue and structural impact.

As no two are the same, you are stuck with one mfg when you spend your 10 billion or so developing an aircraft.

In short all your advantages disappear in the real world (we have yet to see one actually on an aircraft have we?)

on Dec 31, 2017

Does Pratt's three stream engine remind anyone but me of the J58 with the big pipes from somewhere forward (perhaps somewhere on the compressor) to what appears to be the afterburner?

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