Sleekjet From United States of America, joined Jul 2001, 2048 posts, RR: 22 Posted (10 years 5 months 4 weeks 1 day 22 hours ago) and read 2291 times:
Is there some overriding reason why all of our passenger jets have top cruising speed in the 500's? It seems that since it has been this way since the advent of jet engines, there must be a really good reason why they are locked in there.
CitationJet From United States of America, joined Mar 2003, 2457 posts, RR: 3
Reply 2, posted (10 years 5 months 4 weeks 1 day 21 hours ago) and read 2263 times:
I don't think it is a structural issue as much as it the increased in drag as you approach Mach 1. To overcome the drag, it takes much larger engines. Look at the size of the engines on the Citation X, which flies Mach 0.92
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
Pelican From Germany, joined Apr 2004, 2531 posts, RR: 8
Reply 3, posted (10 years 5 months 4 weeks 1 day 20 hours ago) and read 2200 times:
Jets are approaching the sound barrier. The sound barrier is called barrier because a plane needs much force, hence much energy to overcome it. Passenger jets fly as close to the sound barrier as economics allow.
Okie From United States of America, joined Jul 2003, 3144 posts, RR: 3
Reply 5, posted (10 years 5 months 4 weeks 1 day 18 hours ago) and read 2153 times:
Largely an economic plateau.
The non bypass or low bypass turbine engines of the 707, 727, 737-100,200 DC-8,9 880,990's tridents etc etc would cruise about .1mach higher than today's aircraft, but were fuel hogs compared to today's high bypass engine and airframe designs.
So today's high bypass designs traded off about 60 knot's for about 30-40% gain in fuel efficiency. Along with that came different wing designs to operate at the slower speeds with less drag and more lift and more efficiency as well.
Its about $$$
When a propulsion system is developed that can economically propel and aircraft at economical cost and an airframe designed that can do away with the tremendous drag at high mach number then there will be another attempt at higher mach numbers for commercial aircraft.
QantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 25
Reply 8, posted (10 years 5 months 4 weeks 1 day 16 hours ago) and read 2068 times:
It's the same reason all plans for new high-subsonic/sonic/supersonic have been dropped for now, and the reason everyone has mentioned above - economics. More specifically, it's primarily the very high (wave) drag present as an aircraft approaches M 1.0 that drives the economic considerations. Obviously, high-enough power engines and huge amounts of fuel are necessary to overcome that drag. With aviation the way it is at the moment, most operators aren't clamouring for fuel-thirstier aircraft (to say the least!). Accordingly, cruising speeds haven't plateaued due to the impossibility of going any faster (i.e. it is certainly possible to go faster!), but rather due to the impractibility given the current state of aviation, as I said. As our planet is slowly drained of oil, things could very well worsen if alternatives aren't looked into...