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Why Not Make The 747X Go M.95?  
User currently offlineDelta777-XXX From United States of America, joined Jun 2000, 1017 posts, RR: 7
Posted (13 years 5 months 3 weeks 6 days 15 hours ago) and read 1852 times:

Lately there have been a lot of rumors about Boeing dropping the 747X for the "M.95 200 seater".

Why can't Boeing just make it's 747X go M.95??

All of the 747s are pretty fast and fuel efficient. Why not add some new technology or something and make them faster and more efficient??

I understand that the airlines may want something smaller, but if Boeing wants something to compete with the A380, that seems to be great.

Any comments??

8 replies: All unread, jump to last
 
User currently offlineJuul From , joined Dec 1969, posts, RR:
Reply 1, posted (13 years 5 months 3 weeks 6 days 15 hours ago) and read 1830 times:

Developing this new technology is quite expensive. Since Boeing doesn't think there's a big market for A380 / 747X-sized planes, it probably won't be worth the cost to them, and they'd rather try it on a somewhat smaller aircraft, 757/767-size. Besides, incorporating this technology into the aircraft now would probably mean they'd have to delay it by a couple of years.

User currently offlineWidebody From Ireland, joined Aug 2000, 1152 posts, RR: 8
Reply 2, posted (13 years 5 months 3 weeks 6 days 13 hours ago) and read 1809 times:

Aerodynamically, with the aircraft travelling at M0.95, the air flow around some parts of the aircraft will go supersonic.....this has to be designed for.......

User currently offlineBostonBeau From United States of America, joined Sep 2000, 463 posts, RR: 0
Reply 3, posted (13 years 5 months 3 weeks 6 days 12 hours ago) and read 1791 times:

Isn't there effectively a "speed limit" on the oceanic tracks, dictated by the slowest aircraft on the track? I remember the B747 originally flew faster when first introduced, but was slowed down, both to be considerably more economical, and because some of the other aircraft couldn't keep up. I guess they could dedicate tracks to faster/slower aircraft, but it would seem easier if everyone flew at the same speed I guess.

User currently offlineGOT From Sweden, joined Dec 2000, 1912 posts, RR: 1
Reply 4, posted (13 years 5 months 3 weeks 6 days 11 hours ago) and read 1783 times:

It's so expensive to develop and it's very hard for the aerodynamics. I don't think it would work.

GOT



Just like birdwatching - without having to be so damned quiet!
User currently offlineTurbulence From Spain, joined Nov 1999, 963 posts, RR: 20
Reply 5, posted (13 years 5 months 3 weeks 6 days 10 hours ago) and read 1774 times:

The reason is what Widebody said. Some parts of the airplane (specially wing edges) would be going supersonic, and the bigger the wings the worse the effect, mainly structural.

Best turbulences.


User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6451 posts, RR: 54
Reply 6, posted (13 years 5 months 3 weeks 6 days 8 hours ago) and read 1756 times:

Widebody and Turbulence, I think your assumptions are a little wrong. To make a M.95 plane and have supersonic flow around it would be quite stupid. If you have supersonic flow, then better go the full way and make a real supersonic plane.
But it may be just about possible to reach M.95 and still keep the fastest air flow at no more than M.99. I am pretty sure that it's what Boeing is talking about.
But it would be a plane with a dramatically different view compared to ordinary M.8x airliners.
It is a little strange that Boeing hasn't released any information about the plane. But it is quite obvious for aerodynamic people how the poperties of a M.95 plane with max. M.99 airflow must be:
The fuselage must be long, narrow and pointed in both ends, something not very dissimilar to the Concorde.
The pax would call it cramped. The main cabin section of the fuselage would probably not be a straight tube, but instead gradually increase diameter until its thickest point from where it would gradually decrease diameter all way to the tail.
Ordinary windscreens, which the pilots could look out of, would be a difficult subject. To give the pilots some forward view during take-off and landing an artificial view system (TV) would be more likely than the Concorde's drooping nose.
The wing would also have to be different. A wide cord delta wing could be likely.
The only thing, which could come almost off the shelves, would be the engines. Unlike a real supersonic plane a M.95 plane could fly with today's high bypass ratio fan engines without much modification. And since it would not generate a sonic boom, then it can, unlike the supersonic plane, be operated over populated land.
As you see, to make a M.95 airliner is a completely different sort of animal, and it is nothing like putting some more power and some "new technology" on an old 747.

But the main point is that it is so totally unnecessary. If only ground service, baggage handling and traffic imposed delays could be made a lot more efficient, then most of us would gladly travel on a M.50 or M.60 plane instead.

Best regards, Preben Norholm



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineWidebody From Ireland, joined Aug 2000, 1152 posts, RR: 8
Reply 7, posted (13 years 5 months 3 weeks 6 days 8 hours ago) and read 1743 times:

Preben,

All of what you said was correct, the question was whether the 747 speed could be ramped up to M0.95, and the answer to that is no.......Boeing could develop a M0.95 plane with no supersonic flow around it, but you'd have that design consideration in mind when desiging it......

Regards,
WB.....


User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6451 posts, RR: 54
Reply 8, posted (13 years 5 months 3 weeks 6 days 7 hours ago) and read 1733 times:

Exactly, Widebody!
And your last sentence - you'd have that design consideration in mind when desiging it...... means a lot more than most people would normally assume.
Nobody should think about this as just a 10-15% increase in speed. They should rather think about it as 3 times closer to the sound barrier. THREE TIMES CLOSER!!!
Best regards, Preben Norholm



Always keep your number of landings equal to your number of take-offs, Preben Norholm
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