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Max Cruising Speeds - Have They Plateaued?  
User currently offlineSleekjet From United States of America, joined Jul 2001, 2054 posts, RR: 20
Posted (12 years 1 day ago) and read 3095 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.

II Cor. 4:17-18
8 replies: All unread, jump to last
User currently offlineNWB757300 From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 23 hours ago) and read 3077 times:

It has to do with the structural limits of the aircraft. Most cannot handle more than that due to the forms and design of the aircraft.

All max cruising speeds are based on the ability of the airframe to withstand the forces of that speed.

[Edited 2004-05-29 19:33:40]

User currently offlineCitationJet From United States of America, joined Mar 2003, 2627 posts, RR: 3
Reply 2, posted (12 years 23 hours ago) and read 3067 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.
User currently offlinePelican From Germany, joined Apr 2004, 2533 posts, RR: 7
Reply 3, posted (12 years 22 hours ago) and read 3004 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.


User currently offlineMITaero From United States of America, joined Jul 2003, 497 posts, RR: 7
Reply 4, posted (12 years 21 hours ago) and read 2969 times:

As stated above, it's not a structural issue or an engine issue. Drag rise is unbearable very close to Mach 1, so too much fuel is needed to go supersonic. As usual, it comes down to economics.

User currently offlineOkie From United States of America, joined Jul 2003, 3809 posts, RR: 3
Reply 5, posted (12 years 20 hours ago) and read 2957 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.


User currently offlineOly720man From United Kingdom, joined May 2004, 7154 posts, RR: 11
Reply 6, posted (12 years 20 hours ago) and read 2932 times:

With most commercial aircraft following air corridors they all have to go at much the same speed to maintain separation.


wheat and dairy can screw up your brain
User currently offlineAirplay From , joined Dec 1969, posts, RR:
Reply 7, posted (12 years 20 hours ago) and read 2925 times:

Its all about the Benjamin's baby....I mean the "Bordens"!

User currently offlineQantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 22
Reply 8, posted (12 years 18 hours ago) and read 2872 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...


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