Amid all the 787 hoopla....

[Chairboy]

I've also heard that the 747-400 was taken supersonic at least once in level flight during the test regime as part of an effort to document the flutter approaching mach.  

The 400 has a lot more power than the original shipping revision, so this was apparently possible, and the severely swept wing of the 747 resulted in surpring stability.  No interest in certifying it as such, just documenting possible failure modes for dives without getting into trouble that pulling the throttle couldn't fix.

[Viking]

The Concorde needs four afterburners to break through the sound barrier. If you think a 747 can manage that you're delusional. A 727 or 747 would be hard pressed to reach supersonic speeds in a vertical dive, and they would break up from the aerodynamic stresses involved.

[Golfer]

Originally posted by Viking
How many parts fell off?

What makes you think they would?

The 727 is suprisingly fast.  It's no slowpoke and will cruise at M0.88  Here's a pic a good friend of mine took when he flew the 727 at Capital Cargo...



It'll hold together.

[Golfer]

Originally posted by Viking
The Concorde needs four afterburners to break through the sound barrier. If you thing a 747 can manage that you're delusional. A 727 or 747 would be hard pressed to reach supersonic speeds in a vertical dive, and they would break up from the aerodynamic stresses involved.

If you're not going to learn what the capabilities of either of the airplane are then don't bother spouting off shooting from the hip about something you clearly know nothing about.

The Concorde uses the afterburner (or reheat if you're a bloke) to accelerate and maintain Mach 2+  It also does have 4 afterburning engines but doesn't always have to use them at all time.

The Citation X cruises at .92M and has gone supersonic more than a few times in (and out of) flight test.  That's a business jet.

The 727 HAS and the 747-400 probably would but I know even less about it and its stories.  The 747 is also surprisingly fast but I'll let you learn that for yourself.

In case you didn't learn from "The Right Stuff" the sound barrier isn't a brick wall in the sky anymore.

[Viking]

Originally posted by Golfer
The Concorde uses the afterburner (or reheat if you're a bloke) to accelerate and maintain Mach 2+

Don't talk to me about spouting off. The Concorde uses afterburners for take-off and to push through the sound barrier and transonic speed range. Once it is supersonic the Concord continues to accelerate on dry thrust alone to Mach 2 and super-cruise. Do you really think the Concorde could fly on afterburners and still have enough fuel to cross the Atlantic? Are you dimwitted?

Originally posted by Golfer
The 727 HAS and the 747-400 probably would but I know even less about it and its stories.  The 747 is also surprisingly fast but I'll let you learn that for yourself.

Well, then show me something that corroborates these wild stories. The turbo-fan engines would compressor stall from eating supersonic airflow. The engine nacelles would be ripped off from the hugely increased drag at Mach 1. The plane would fall apart.

[wooley]

Originally posted by Viking
Don't talk to me about spouting off...

What he said...

[Golfer]

First part should have read:

The Concorde uses afterburners to accerate to Mach2+ and it maintains that speed.  Maintaining mach 2 is a far cry from simply making it to Mach 1 and it is not a fair statement to say that the Concorde requires the 4 Olympus motors just to get to Mach 1.

I don't need to provide anything.  How about you show us where and how the aircraft would break apart just.

It shouldn't be too hard for you to school this simple dimwit if you're right.

[Mark Luper]

Originally posted by Viking
Don't talk to me about spouting off. The Concorde uses afterburners for take-off and to push through the sound barrier and transonic speed range. Once it is supersonic the Concord continues to accelerate on dry thrust alone to Mach 2 and super-cruise. Do you really think the Concorde could fly on afterburners and still have enough fuel to cross the Atlantic? Are you dimwitted?




 

Well, then show me something that corroborates these wild stories. The turbo-fan engines would compressor stall from eating supersonic airflow. The engine nacelles would be ripped off from the hugely increased drag at Mach 1. The plane would fall apart.

Yup, Viking really doesn't know much about going supersonic. BTW you did know that supersonic speed changes with altitude didn't you?

Mark

[Toad]

Hoot Gibson went momentarily supersonic in a TWA 727 (as shown on flight recorder) and only lost the #7 slat.

Had the slats been retracted he

a) probably wouldn't have been in that situation to begin with

b) but the slat probably would have stayed on had he dove to that momentary speed with them in.

I've seen .89 many times in a 727 in cruise and descent, a few in the .9's in descent with one particular Captain who shall remain nameless. Nothing fell off.

[WilldCrd]

She canna take de strain cappin!
me bairns me por poor bairns!!

[Golfer]

Originally posted by Toad
Hoot Gibson went momentarily supersonic in a TWA 727 (as shown on flight recorder) and only lost the #7 slat.
 

I just went through school on a new airplane.  The instructors at this FSI were almost all ex TWA or furloughed American (usually one and the same) guys.  I head that story and many others that all seemed to revolve around JFK and St. Louis.  Who knew so much went on in the Gateway city?

[Toad]

Originally posted by Golfer
ex TWA or furloughed American (usually one and the same) guys.

Which is because their brother Airmen at AA just couldn't resist giving them a jolly good rogering when they had the chance.

I know I just missed the best years of the industry but my years were pretty good. That said, I am damn glad to be out of it now.

[Ripsnort]

I just checked Tex's book when I got home, found no mention of the 727 testing so I think I confused it with the high speed stall tendency of the B-47.

I did find a 727 that broke mach 1 by accident though, here is the story:

Apparently this  flight was known as TWA-841. 1979. The plane was under the command of Captain (Hank?) Gibson. He was 44 years old at the time. The crew found that the plane performed better with 2-degrees flaps selected at high altitude. They were at either FL390 or FL410. To prevent the slats from extending at high-speeds, which could cause an upset, they pulled the circuit-breaker to the leading edge devices, then extended the flaps 2 degrees.

In this time the Flight Engineer had left the cockpit to drain his lizzard, when he came back, he noticed the breaker had popped. So, logically, he assumed it had popped on its own. So he reset it...

Oh ****!

Slats 2,3,6 and 7 deployed. 2 3 and 6 tore off, leaving 7 on. The crew probably tried to bring the flaps up. Either way it caused the plane to roll sharply. The autopilot didn't disconnect as it should have and the plane started to lose altitude as the nose went below the horizon. The Autopilot eventually did disconnect though. The planes speed began to rise, and Gibson began desperately trying to regain control. With the slat extended the roll wouldn't stop. The plane was picking up speed, windscreen noise was getting deafening, and the plane was starting to rattle like crazy. The plane went vertical, the slat finally tore off. The plane started shredding parts as well. A spoiler panel came off and small pieces of the aircraft came off. The slat coming off stopped the roll and enabled them to regain control. They pulled over 4g's trying to pull up and the plane is now supersonic. They can't slow her down, the lights on the ground below seem to explode towards them, and she's falling like a rock. The Captain yanked the throttles to idle, and then extended the landing gears in a desperate effort to slow down. He probably lost his gear-doors right there, and heavily damaged the landing gear. They were now only at 5,000 feet when they pulled up. They fell like 34,000 to 36,000 feet in 62 seconds. That is the largest amount of altitude an airliner has ever lost without actually hitting the ground.

Captain Gibson re-diverted 841 to Detroit (the upset occured over Saginaw Michigan). They declared an emergency, and headed over to Detroit, touched-down uneventfully. Once they came to a stop, the nose-gear collapsed from all the damage it sustained from being extended at high-speed. I assume they did an emergency evacuation.

I don't know what happened to Captain Gibson exactly, but I do know he got into some deep ****!

Another story on the incident:
http://www.flightglobal.com/articles/1995/02/01/27971/saginaw-ghost.html

[Viking]

Originally posted by Golfer
First part should have read:

The Concorde uses afterburners to accerate to Mach2+ and it maintains that speed.  Maintaining mach 2 is a far cry from simply making it to Mach 1 and it is not a fair statement to say that the Concorde requires the 4 Olympus motors just to get to Mach 1.

From http://www.concordesst.com

“Concorde is the only civil airliner in service with a 'military style' afterburner system installed to produce more power at key stages of the flight. The reheat system, as it is officially known, injects fuel into the exhaust, and provides 6,000Lb of the total available thrust per engine at take off. This hotter faster exhaust that is used on take off and is what is mainly responsible for the additional noise that Concorde makes. The reheats are turned off shortly after take off when Concorde reaches the noise abatement area. The reheats are turned back on, by the piano switches behind the thrust leavers, for around 10 minutes once the aircraft is clear of land, to push the aircraft through Mach1 and on to Mach1.7 where they are no longer required.”

Originally posted by Mark Luper
Yup, Viking really doesn't know much about going supersonic. BTW you did know that supersonic speed changes with altitude didn't you?

Mark

Not directly, it changes with the density and temperature of the air (which changes with altitude), but that doesn’t change the effects of hitting Mach 1 with a plane not designed for transonic flight. The drag increase is tremendous, and if any common airliner has ever hit Mach 1 (as Toad suggests) the plane will start to fall apart rapidly.

In a strong tail wind situation a subsonic airliner can still have a ground speed of beyond Mach one, but not the air speed. So even if radar or gps tells you you’re going supersonic, you’re not.

And as Ripsnort’s post explains Gibson’s 727 started to fall apart long before he allegedly went supersonic, and the plane lost a lot more than one slat. However I’m a lot more willing to believe that the 727 went transonic very close to supersonic and was just experiencing local supersonic airflow that rendered the elevators useless (just like on a P-38 for example). That the aircraft itself went supersonic I find highly unlikely … seeing how it survived.


Btw. Golfer, it's pretty scary that you are allowed to fly an aircraft. One would think it would require a modicum of intelligence and knowledge of the physics involved.


Last post for tonight. Good night Gentlemen.

[RAIDER14]

The 727s maximum speed is .90 Mach and the 747-400 maximum speed is Mach 0.92(630mph) so they could probably break the sound barrier in a dive or level flight.


If you flew on the Concorde you would receive more radiation due to the higher altitude