747........Supersonic.....?

First of all is the 747 structually sound, to go supersonic?
We know how powerful the engines are!

I, obviously am aware that it was not designed to do this, but can anyone tell me if it is actually structually capable?

Or if it has ever been achieved unintentionally, i.e, forced to dive, weather etc etc...!?

I await your replies on this topic, cheers!...

[edit on 7-6-2005 by John bull 1]

ANYONE!?
Sorry i know i`m impatient!......

There is some commentary about it here: www.airdisaster.com...

and here:

yarchive.net...

But it doesn't seem like the 747 has every managed to break Mach 1 from my search.

If in need, Google it!

Actually I've heard (via TV shows) that the 747 regularly goes supersonic during Boeing presale flight tests.

edit:

I should add, just barely

[edit on 6/7/2005 by djohnsto77]

im no expert, but the 747 seems, to me, to large to reach the speed of sound with the engines it has. and in my research ive never heard anything about it

I think it was just in dives done during structural flight-worthiness tests.

Have google`d it myself, but to no avail.

Hence why i put it out to you guy`s!

Would be interesting to know more about, whether, this can be achieved, safely and the whole feasability of it all.

From what I remember I saw on TV, if it's accurate, the 747 has briefly gone supersonic in flight tests, but it's certainly not designed to travel at that speed in regular service.

Hope that helps.

I spoke with several structures engineers; they all say that there is no way the 747 could even reach supesonic speeds before being destroyed by shockwave buffeting

"Off_the_Street"

Duncan Kunz
[email protected]

Army Programs
Rotorcraft Division
Intgrated Defense Systems
The Boeing Company
480-891-2525

Well thanks for that, OFF_THE STREET. I think most of us thought that.

But i am sure i read somewhere, that the B52 had surpassed MACH 1, only slightly, mind you, but nevertheless, achieved.

So, this being accurate, then i would of thought, that MACH1 would of been harder to achieve than in the 747.

I don`t know, but i will google it and try and find.
If anyone else could also, cheers!

Not really, I don't know if its true that the B-52 has exceeded mach 1 but I would find that more believable than a 747 doing it. The B-52 is much slimmer and with a much thinner wing. The HP Victor managed to go supersonic in a shallow dive but was the only V-bomber type to do it. The 747 is just too fat and blunt to be propelled through the sound barrier IMHO even if it was structurally safe to do so.

I am curious, what would make you think a 747 was more likely to go supersonic than a B-52?

I know that I have flown in a 767 and in a slipstream is said we were at 1000kph or very close to it, OtS is right though, those aircraft shouldn't survive supersonic flight so I guess the speed reading was off on the jet I flew in...

Having, many years ago, worked on creating the skins that go into creating the 747, I can say, without hesitation... I don't want to be on one when it goes supersonic for any length of time...

Putting it into perspective for you... Side to engineered scale, what you have is, essentially, a flying aluminum beer can with some ribbing... Quite comfortable to ride in as it is designed to do, but probably scarier than all get out at a mach or near mach range.... But then, again, I used to like jumping from perfectly good airplanes, and now get nose bleeds at heights in excess fo 10 feet.

Originally posted by GrOuNd_ZeRo
I know that I have flown in a 767 and in a slipstream is said we were at 1000kph or very close to it, OtS is right though, those aircraft shouldn't survive supersonic flight so I guess the speed reading was off on the jet I flew in...

The speed you saw was GROUND SPEED, which has nothing to do with Mach number. Mach is based on AIRSPEED. You can read about the distinction here.

www.aerospaceweb.org...

Most commercial airliners are capable of reaching reaching very low supersonic speeds in a shallow dive from high altitude where the pressure is low. The first plane to do so was a DC-8 that reached Mach 1 during a test flight in 1961 over Edwards AFB.

www.dc8.org...

However, the plane did so during a dive from over 52,000 ft and pulled out at 41,000 ft. Most airliners today have a service ceiling around 40,000 ft, so they probably wouldn't even be able to climb that high in the first place. Even so, the structure of an airliner ought to be able to withstand a brief excursion into supersonic flight so long as it was at high enough altitude. It is not recommended, of course, since these planes were not intended to be flown in the harsh aerodynamic environment near Mach 1.

What the hell is the difference between ground speed and airspeed? ground speed is when the vehicle is traveling ON the ground, and airspeed, well you get what I mean.

And by the way, it clearly said Airspeed on the console, i'm not that dumb

However I do agree with your analogy that an aircraft is basically a flying beer can with ribs and that's completely true.

And btw, Mach speed is when an object passes the 1000kph treshhold, a Mr. Mach invented this term, and it's faster than sound (super-sonic), so don't lecture me on this.

Actually 1000kph is strictly subsonic, and is definitely not the threshold for mach 1 at any altitude. so your passenger jet might well have reached that speed. The speed of sound varies between 1,062 and 1,225 kph depending on altitude. The transonic regime is around 1,100kph at 20-30,000ft so to have truly gone supersonic you would have needed to go about 150-200kph faster. Sorry for the lecture

[edit on 8-6-2005 by waynos]

Originally posted by GrOuNd_ZeRo
What the hell is the difference between ground speed and airspeed? ground speed is when the vehicle is traveling ON the ground, and airspeed, well you get what I mean.

And by the way, it clearly said Airspeed on the console, i'm not that dumb

Airspeed is not a true speed indication, it must be calculated, check the link below, it’s based on temperature, altitude, and humidity read from the petit tubes and static pressure port.

So they might have been just pulling your leg. Sounds like a pilot's sense of humor....lol

Indicated airspeed
Aircraft display an Indicated Airspeed (abbreviated IAS) on an instrument called an airspeed indicator. Indicated airspeed will differ from true airspeed ("TAS") at air densities other than some reference density. Air density is affected by temperature, atmospheric moisture content (humidity), and pressure altitude.

As far as going Mach goes, when I worked on the ramp, one mechanic was telling me that the MD-80’s had something called Mach Trim, which would trim down the nose of the plane if it should break the sound barrier. The sound barrier as was already stated tends to change with the pressure and density as well.

Originally posted by waynos
Actually 1000kph is strictly subsonic, and is definitely not the threshold for mach 1 at any altitude. so your passenger jet might well have reached that speed. The speed of sound varies between 1,062 and 1,225 kph depending on altitude. The transonic regime is around 1,100kph at 20-30,000ft so to have truly gone supersonic you would have needed to go about 150-200kph faster. Sorry for the lecture

[edit on 8-6-2005 by waynos]

Crap the speed of sound is over 1000Mph? Well you better call NASA and correct them on that then. They seem to think its around 761Mph at sea level static conditions....

www.grc.nasa.gov..." target="_blank" class="postlink">speed of sound

If we consider the atmosphere on a standard day at sea level static conditions, the speed of sound is about 761 mph, or 1100 feet/second. We can use this knowledge to approximately determine how far away a lightning strike has occurred.

Defcon, a mile is not the same as a kilometer so don't be too smug, hey? NASA knows what its talking about but do you?