So my questions remains. If this fan that is in effect nothing more than a shrouded propeller (fixed pitch, at that), providing about 80% of the thrust and regularly manages to get these aircraft to cruise at almost sonic speeds - then why aren't all aircraft designed with this ingenious high speed device?
I suspect it's very simple - the sheer excess in horsepower is providing these numbers. The abandoned propfan experiments showed that it did not suffer in speed compared to the shrouded fan, so it's certainly not the case that a prop can't be just as fast or effective.
I have a sneaking suspicion that if you designed an aircraft with exactly the same amount of horsepower powering either a shrouded fanjet, or an unshrouded fan/prop, they would probably be exactly as fast and fly as high.
Hi Adam,
At a quick glance, the mathematics do not appear to support your suspicion. You may wish to check:
Turbofan Thrust
Turboprop Thrust Propeller Thrust
Propeller Analysis
rgds