3 ms·

> the Europeans had a supersonic airliner and the US didn't Technically no, but the 747 is fast, almost too fast in these days of fuel economy. The 747 was d

> the Europeans had a supersonic airliner and the US didn't Technically no, but the 747 is fast, almost too fast in these days of fuel economy. The 747 was designed by Boeing to do M.87 (Pan Am wanted M.9) , though it now sits around M.855 (913 km/h) [1] due mainly to the requirement of fuel efficiency over raw speed. Almost Mach 1. How did Boeing designers get this speed? Hint: The hump and area rule (min drag > M.8) [2] Now a DC8 was pushed to M1.012 under special conditions. [3] And as a point of interest, Air Force One (VC-25A) is rated at M0.92 (1015 km/h). [4] [1] http://www.boeing.com/boeing/commercial/747family/pf/pf_400er_prod.page http://www.boeing.com/boeing/commercial/747family/pf/pf_400e...? [2] http://www.aerospaceweb.org/question/performance/q0150a.shtml http://www.aerospaceweb.org/question/performance/q0150a.shtm... [3] https://en.wikipedia.org/wiki/Douglas_DC-8#Production_and_testing https://en.wikipedia.org/wiki/Douglas_DC-8#Production_and_te... [4] https://en.wikipedia.org/wiki/Boeing_VC-25#Specifications_.28VC-25A.29 https://en.wikipedia.org/wiki/Boeing_VC-25#Specifications_.2...

idlewords 12y ago
The high speed of the 747 is a function of its wing sweep. The hump and area rule have nothing to do with it.
- bootload 12y ago
  "... The fastest airplane out there today is the 747. Not one of them has been able to match the cruise speed of the 747. That indicates to me that it’s a high-technology airplane ..." Joe Sutter [0] wing sweep alone doesn't explain why the 747 is the fastest subsonic transport to date. If it did, competitors would have copied the idea. I'm curious why? Boeing describe it as a combination of wing design, engine, electro-mechanical systems. Maybe I should ask Boeing. [0] http://www.boeingblogs.com/randy/archives/2006/08/father_knows_best.html http://www.boeingblogs.com/randy/archives/2006/08/father_kno...
  - idlewords 12y ago
    Because the penalty for that speed is higher fuel burn. That's why Boeing is having trouble selling the 747-8, and why four-engine airliners in general are getting phased out. My source for the wing sweep thing is also Joe Sutter, in his wonderful book. Also highly recommend Widebody, by Clive Irving, which is sadly out of print.

idlewords 12y ago

The high speed of the 747 is a function of its wing sweep. The hump and area rule have nothing to do with it.

bootload 12y ago
"... The fastest airplane out there today is the 747. Not one of them has been able to match the cruise speed of the 747. That indicates to me that it’s a high-technology airplane ..." Joe Sutter [0] wing sweep alone doesn't explain why the 747 is the fastest subsonic transport to date. If it did, competitors would have copied the idea. I'm curious why? Boeing describe it as a combination of wing design, engine, electro-mechanical systems. Maybe I should ask Boeing. [0] http://www.boeingblogs.com/randy/archives/2006/08/father_knows_best.html http://www.boeingblogs.com/randy/archives/2006/08/father_kno...
- idlewords 12y ago
  Because the penalty for that speed is higher fuel burn. That's why Boeing is having trouble selling the 747-8, and why four-engine airliners in general are getting phased out. My source for the wing sweep thing is also Joe Sutter, in his wonderful book. Also highly recommend Widebody, by Clive Irving, which is sadly out of print.