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Fastest Normal Cruise Speed  
User currently offlineKuja From Bermuda, joined Aug 2013, 80 posts, RR: 0
Posted (1 year 2 weeks 6 days ago) and read 7642 times:

A topic that has fascinated me for a long time - excluding the supersonic superlatives (Concorde and the Tu-144), which airliner had the fastest in-service cruise speed? There have been various threads in the past about this, but all of them seemed to be largely anecdotal and focused on the Vmo / Mmo.

From previous topics, some seemed to suggest that the first and second generation jets cruised rather quicker than the modern day models, but from what I can find, the DC-8 and 707 seemed to top out at around Mach 0.88 and cruised around 0.85 - very similar to modern jets like the 777. It seems that the 727 could reach 0.90, but fuel burn at that speed was apparently prohibitive even in the early days.

The 747 has always been fast; it seems that the 747SP and, from past comments, the Rolls-Royce powered -200B were the quickest of them, and the SP was designed for a high cruise speed - apparently it cruised at 0.88 and could go up to its 0.92 limit without too much difficulty? The TriStar was also known as a quick ship, but, again, I don't know how fast they normally operated.

The Convair 880 and particularly the 990 seem to be likely candidates here, but I can't find reliable figures for how fast they actually operated.

I know that the VC10 still holds a few speed records as well, but, again, I can't find reliable figures for it. Depending on source, the Mmo is given as high as 0.94 or as low as 0.88, with cruise varying between 0.90 and 0.86.

So, what subsonic airliner had the fastest cruise speed in service? 747SP? CV-990? VC10? Or something completely different?

Thank you for any replies.

35 replies: All unread, showing first 25:
 
User currently offlinetimz From United States of America, joined Sep 1999, 6835 posts, RR: 6
Reply 1, posted (1 year 2 weeks 5 days 5 hours ago) and read 7411 times:

Quoting Kuja (Thread starter):
The Convair 880 and particularly the 990 seem to be likely candidates here, but I can't find reliable figures for how fast they actually operated.

Bet you never find any. People like to think Convairs were fast, but no one has actual data.

Mach is all you care about? If you want the fastest airspeed you'll need to stay below 25000 ft.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17040 posts, RR: 66
Reply 2, posted (1 year 2 weeks 5 days 4 hours ago) and read 7364 times:

Quoting timz (Reply 1):
If you want the fastest airspeed you'll need to stay below 25000 ft.

Quite. When Mike Lithgow broke the world speed record in a Supermarine Swift, he did it at low level in Lybia, flying along an oil road. High temperatures mean a but of an edge.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineKuja From Bermuda, joined Aug 2013, 80 posts, RR: 0
Reply 3, posted (1 year 2 weeks 5 days 4 hours ago) and read 7354 times:

Quoting timz (Reply 1):
Mach is all you care about? If you want the fastest airspeed you'll need to stay below 25000 ft.

No, not at all. I know that below 25000 ft speed is measured in knots; in my initial post I used Mach because it seemed to be easier to find approximate figures in Mach for the sake of comparison. Apologies for the poor original post.   

Quoting timz (Reply 1):
Bet you never find any. People like to think Convairs were fast, but no one has actual data.

I suspect that you are right, but I thought that it wouldn't hurt to ask. I assume a large part of the reason for their city pair records was the lack of the 250 kts restriction under 10000 ft when they operated?


User currently offlinetimz From United States of America, joined Sep 1999, 6835 posts, RR: 6
Reply 4, posted (1 year 2 weeks 5 days 1 hour ago) and read 7276 times:

Quoting Kuja (Reply 3):
I assume a large part of the reason for their city pair records

Offhand guess: 707/720s have more records than Convairs.


User currently offlineMrBuzzcut From United States of America, joined Jan 2008, 64 posts, RR: 0
Reply 5, posted (1 year 2 weeks 4 days 23 hours ago) and read 7205 times:

It wasn't normal cruise by any means, but the DC-8 is the only airliner I know of that has gone over Mach 1 and lived to tell the tale. Sure, it was a test flight, and they were in a dive, but cool nonetheless.

Read more: http://www.airspacemag.com/history-o...-Will-Never-Try-It.html?c=y&page=1


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17040 posts, RR: 66
Reply 6, posted (1 year 2 weeks 4 days 19 hours ago) and read 7138 times:

Quoting Kuja (Reply 3):
I know that below 25000 ft speed is measured in knots;

That's just a convention for practicality. Speed can always be measured in knots. Above the crossover altitude the convention (and regulation) is Mach number, but there certainly is a Mach number under the crossover altitude.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineFlyboyOz From Australia, joined Nov 2000, 1986 posts, RR: 25
Reply 7, posted (1 year 2 weeks 4 days 17 hours ago) and read 7100 times:

Aircraft Specifications
The CV-990 was built by the Convair Division of General Dynamics Corp., Ft. Worth, Tex., in 1962.

The aircraft was used for commercial passenger service by American Airlines and Modern Air Transport until acquired by NASA in 1975 for use as a research aircraft at the Ames Research Center, Moffett Field, Calif.

The aircraft, which has a cruise speed of 432 kph (496 mph), is 139 feet long and has a wing span of 120 feet. Landing speeds of the CV-990 duplicate those of the space shuttle orbiters - about 230 kph (256 mph).

It is powered by four General Electric CJ805-23 engines, each producing 16,000 pounds of thrust.

From the website:
http://www.nasa.gov/centers/dryden/news/FactSheets/FS-027-DFRC.html



The Spirit of AustraliAN - Longreach
User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2409 posts, RR: 13
Reply 8, posted (1 year 2 weeks 4 days 16 hours ago) and read 7089 times:

If operated commercially and called "airliners", would the Cessna Citation X or the Gulfstream G650 take the cake?


David



Keeping calm is terrorism against those who want to live in fear.
User currently offlineKuja From Bermuda, joined Aug 2013, 80 posts, RR: 0
Reply 9, posted (1 year 2 weeks 4 days 7 hours ago) and read 6942 times:

Quoting FlyboyOz (Reply 7):

Interesting, thanks for that.

Some figures I came across in a scan of an old 'book of airliners' from the '60s gives some speeds for the Convair jets:
CV-880-22
  Max Cruise: 535 kts at 22,500 ft (Mach 0.88)
CV-990A-30
  Max Cruise: 540 kts at 21,200 ft (Mach 0.88)
  Normal Cruise: 485 at 35,000 ft (Mach 0.84)

So if that is to be trusted, it seems that the Convairs were fast, but not as blisteringly quick as some had said. As to how fast they were operated in service, I guess unless a former Convair pilot with a good memory pops up, we won't know.

Some speeds given for the VC10:
Standard VC10
  Max Cruise: 502 kts at 25,000 ft (Mach 0.833)
  Regular Cruise: 480 kts at 25,000 ft (Mach 0.797)
Super VC10
  Max Cruise: 505 kts at 31,000 ft (Mach 0.859)
  Regular Cruise: 478 kts at 38,000 ft (Mach 0.832)

Quoting flyingturtle (Reply 8):
If operated commercially and called "airliners", would the Cessna Citation X or the Gulfstream G650 take the cake?

Yes, that was one of the things that sparked my curiosity on this subject - whether any airliners from the past could match the fastest business jets of today. It seems quite possibly not.


User currently offlinetimz From United States of America, joined Sep 1999, 6835 posts, RR: 6
Reply 10, posted (1 year 2 weeks 4 days 2 hours ago) and read 6756 times:

Quoting FlyboyOz (Reply 7):
From the website:
http://www.nasa.gov/centers/dryden/n....html

Sure nuff, you quoted it correctly. That site needs work.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25338 posts, RR: 22
Reply 11, posted (1 year 2 weeks 4 days ago) and read 6727 times:

Quoting FlyboyOz (Reply 7):
Landing speeds of the CV-990 duplicate those of the space shuttle orbiters - about 230 kph (256 mph).

That's only when it was used to simulate the space shuttle. The standard landing speed in airline use was in the same range as other competitive types.


User currently offlineMax Q From United States of America, joined May 2001, 4522 posts, RR: 18
Reply 12, posted (1 year 2 weeks 3 days 20 hours ago) and read 6658 times:

The question was 'normal cruise speed' not maximum.


In other words a cruise mach number that provides for the most economical operation, in that respect I think the B747 in all of its fantastic versions has to be the fastest.


.84 to .86 Mach is quite normal on the queen of the skies and economical, it can also go considerably faster if it needs to, up to .92 Mach.



The best contribution to safety is a competent Pilot.
User currently offlineC680 From United States of America, joined Apr 2005, 588 posts, RR: 0
Reply 13, posted (1 year 2 weeks 3 days 13 hours ago) and read 6542 times:

As of today, fastest certified, sub sonic, civil aircraft made is Cessna Citation X with a Mmo of 0.935

The gulfstream 650 Mmo is 0.93

All models of 747 Mmo is 0.92

787 Mmo is 0.90

L-1011 Mmo is 0.90

777 Mmo is 0.89

A380 Mmo is 0.89

DC-10 Mmo is 0.88

767 Mmo is 0.86

A330 Mmo is 0.86

A320 Mmo is 0.82



My happy place is FL470 - what's yours?
User currently offlineflylku From United States of America, joined Apr 2006, 808 posts, RR: 0
Reply 14, posted (1 year 2 weeks 3 days 13 hours ago) and read 6540 times:

Quoting Kuja (Reply 3):
It wasn't normal cruise by any means, but the DC-8 is the only airliner I know of that has gone over Mach 1 and lived to tell the tale. Sure, it was a test flight, and they were in a dive, but cool nonetheless.



It is all heresay but I have it on good authority (or maybe just an aviation legend) that the 747 has done it in level flight

1) A friend and Naval Aviator knew a guy who was a test pilot on the 747 and claims they did it. If you think about the shape of the fuselage conforms to he area rule. So then the big worry is flutter and control lock on he control surfaces.

... so I thought I would ask around.

2) An collegue was the FE on Air Force One when they transitioned to the 747 and flew some of the acceptance test flights. I told him the story and he said he had not heard it but believed it was plausible.

3) I was killing time during a delay and shooting the bull with a 737 captain who had been a 747 FO and told him the story and he said he believed it was possible. He said one night they had lots of extra pull and started bumping up the speed in the FMS. He said they got the airplane to mach .90 or .95 (I forget which but I really think he said .95) and he was confident the airplane easily could have gone faster but the computer would not accept anything higher.

I think a BA 747 captain told me their normal cruise is .83 and high speed cruise is .85 ... somehting like that? Its just fuel.



...are we there yet?
User currently offlineflyingturtle From Switzerland, joined Oct 2011, 2409 posts, RR: 13
Reply 15, posted (1 year 2 weeks 3 days 11 hours ago) and read 6505 times:

Quoting flylku (Reply 14):

And there is also a story about a supersonic CV 990 somewhere in the US. The pilots were sacked after that revenue flight. But I do not know when and where this happened...




David



Keeping calm is terrorism against those who want to live in fear.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17040 posts, RR: 66
Reply 16, posted (1 year 2 weeks 3 days 9 hours ago) and read 6471 times:

Quoting flylku (Reply 14):
1) A friend and Naval Aviator knew a guy who was a test pilot on the 747 and claims they did it. If you think about the shape of the fuselage conforms to he area rule. So then the big worry is flutter and control lock on he control surfaces.

All modern aircraft conform to the area rule to some extent.

If memory serves when an Isreali cargo conversion firm tested their 747, they dove it at M0.97.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineMax Q From United States of America, joined May 2001, 4522 posts, RR: 18
Reply 17, posted (1 year 2 weeks 3 days 5 hours ago) and read 6403 times:

During flight test the B747 was taken up to .99 Mach.


Bear in mind that at that speed the airflow over much of the airframe was already supersonic.


China Airlines did take their -SP supersonic when they did their inadvertent 'Air Display' over the Pacific.



The best contribution to safety is a competent Pilot.
User currently offlineKuja From Bermuda, joined Aug 2013, 80 posts, RR: 0
Reply 18, posted (1 year 2 weeks 3 days 4 hours ago) and read 6381 times:

Quoting Max Q (Reply 12):

  

Quoting flylku (Reply 14):
I think a BA 747 captain told me their normal cruise is .83 and high speed cruise is .85 ... somehting like that? Its just fuel.

The flight crew of a VS 744 told me that their regular cruise was 0.84 to save fuel, sometimes 0.83. Interestingly, they mentioned that the BA 747 flight from LHR to JNB was known as 'the bullet' and cruised at 0.86 most of the way. This may have since been slowed down to save fuel, of course.


So, as far as airliners are concerned, it seems that the fastest regular cruise was the 'hot rod' 747, the SP? That would apprently cruise at 0.88 regularly because of its lighter weight and the beneficial aerodynamic effect of the upper deck ending above the wing as opposed to ahead of it as on the Classics up to that point.
Judging from reports from Iran Air flights on the type, though, the ones still flying likely cruise closer to 0.84 now for economy.

A couple of wildcards would be the HS Trident (not quick to get off the ground but apparently plenty quick in flight) and the Tu-154B (which certainly was faster than the later -154M, but at the expense of what was described as 'alarming' fuel economy even in the days of cheap fuel    )


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25338 posts, RR: 22
Reply 19, posted (1 year 2 weeks 3 days 2 hours ago) and read 6345 times:

Quoting Max Q (Reply 17):
China Airlines did take their -SP supersonic when they did their inadvertent 'Air Display' over the Pacific.

Isn't that just speculation? If memory correct the accident report only refers to "high speed" but doesn't specifically say it exceeded Mach 1.


User currently offlinePellegrine From United States of America, joined Mar 2007, 2447 posts, RR: 8
Reply 20, posted (1 year 2 weeks 2 days 21 hours ago) and read 6300 times:

I've read that the CV-990 cruised at M0.90-M0.92. I've also read that a lot of airlines slowed them down to save fuel.

I'd love to bring a CV-990 back in the air if a serviceable one existed anymore...too bad they've all been chopped to hell.



oh boy!!!
User currently offlineBoeingGuy From United States of America, joined Dec 2010, 3076 posts, RR: 7
Reply 21, posted (1 year 2 weeks 2 days 5 hours ago) and read 6130 times:

Quoting MrBuzzcut (Reply 5):
It wasn't normal cruise by any means, but the DC-8 is the only airliner I know of that has gone over Mach 1 and lived to tell the tale. Sure, it was a test flight, and they were in a dive, but cool nonetheless.

Didn't the TWA 727 that rolled over Michigan exceed Mach 1?

Tragically PSA 1771 broke the sound barrier also.

For mainline commercial jets today, the 747-8 is the fastest.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25338 posts, RR: 22
Reply 22, posted (1 year 2 weeks 1 day 23 hours ago) and read 6053 times:

Quoting BoeingGuy (Reply 21):
Tragically PSA 1771 broke the sound barrier also.

Do you have a source for that? I can't find any official reference to that (NTSB etc.)


User currently offlineMax Q From United States of America, joined May 2001, 4522 posts, RR: 18
Reply 23, posted (1 year 2 weeks 1 day 21 hours ago) and read 6004 times:

Quoting Kuja (Reply 18):

Judging from reports from Iran Air flights on the type, though, the ones still flying likely cruise closer to 0.84 now for economy.

There's a common misconception that slower always saves fuel and / or is more economical.
Quite often you can save fuel by flying faster into a headwind (less time spent flying into the wind means less fuel burnt)


Not to mention, less time in the air is less time wearing out all Aircraft components, less pay for crews, etc..


It's just not that simple and many Aircraft are designed to be most economical at higher Mach, flying slower can actually increase drag.



The best contribution to safety is a competent Pilot.
User currently offlinegeorgiaame From United States of America, joined Aug 2005, 980 posts, RR: 6
Reply 24, posted (1 year 2 weeks 1 day 10 hours ago) and read 5927 times:

Quoting Starlionblue (Reply 6):
Above the crossover altitude the convention (and regulation) is Mach numbe

For a non pilot and a non engineer, my question is why?



"Trust, but verify!" An old Russian proverb, quoted often by a modern American hero
25 Starlionblue : I'll try to explain it simply but this will take a while. I also may make some mistakes which no doubt the experts will jump on. Down here on the sur
26 YQBexYHZBGM : I've read through this thread, and read about speed in dives and at maximum thrust. But, in answer to the original question, I have always been led to
27 georgiaame : Starlionblue, thank you very much! As a non engineer, supersonic has fascinated me, especially bad things that begin t ohappen in the transonic range.
28 Post contains images vikkyvik : To be perfectly clear, since you mentioned IAS a lot in your post, Mach = TAS (true airspeed) / LSS. I would assume (and correct me if I'm wrong), th
29 Post contains links and images Starlionblue : Indeed. I just didn't want to overcomplicate things. Here is an ECTM graph. The easiest way to visualize the relationship between Equivalent Airspeed
30 timz : A 707 could perhaps maintain 600 mph at 22000? ft altitude, burning 50%? more fuel per mile than it would at Mach 0.82 at 35000 ft. So if a 707-120 i
31 Trijetsonly : I was always tought that the second fastest commercial jetliner in service during the 1990s was the Tupolev Tu-154. Unfortunately I have no data to re
32 Post contains images Kuja : Indeed, I did consider the Soviet jets. The Il-62, Il-86 and Il-96 were not particularly quick planes, from what I can tell; the Tu-134 appears to ha
33 Trijetsonly : In my bookshelf I've just found a German ATC (DFS) training book by the "DFS Air Navigation Services Academy" with technical data of many aircraft, t
34 Max Q : Those numbers are inaccurate, B727 Max Mach is .9 B747 Max Mach is .92
35 Fabo : There is one thing to consider when discussing this - older aircraft usually flew lower than their current counterparts... and that means flying faste
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