747400sp
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Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 11:21 am

I was told, that when a Boeing 747 is pushed to it's full compacity of speed in flight, it make for a ruff and uncomfortable ride. I just wanted to know have anybody ever flown on a 747 during a full power run in flight to confirm this.

Thank You
 
SPREE34
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 12:16 pm

Nope.

I rode an L1011 at mach.88 and it was perfectly smooth.
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DLKAPA
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 12:19 pm

During the 747 test program, they did high power dives, the airspeed indicators read mach .99, it can be said that parts of the plane (the top of the wing where air moves faster) probably exceeded the sound barrier for a brief period.
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spacecadet
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 1:05 pm

I was told, that when a Boeing 747 is pushed to it's full compacity of speed in flight, it make for a ruff and uncomfortable ride. I just wanted to know have anybody ever flown on a 747 during a full power run in flight to confirm this.

Not really sure what you mean by this. I have flown on a 747 at Mach 0.92, which is its maximum cruising speed. We had left the gate late and were making up time. The flight was fine.

No airplane ever cruises at "full power". Leave the engines running at full power after takeoff and either the engines or the airplane will eventually rip themselves apart, depending on where the stress points are. All commercial airplanes are powerful enough to speed themselves well beyond their maximum cruising speed. (Edit: I realize this is an extreme over-simplification of what happens in an overspeed condition - there are all sorts of things that happen to an airplane in extreme and prolonged overspeed.)

If you were in *any* airplane that was cruising at full power for very long, you'd be in for a pretty rough and uncomfortable ride. And you'd more than likely end up dead.

[Edited 2005-08-07 06:11:57]

[Edited 2005-08-07 06:12:49]
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pwm2txlhopper
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 1:06 pm

Quoting 747400sp (Thread starter):

I'm sure there have been hundreds of thousands of HR's transported on 747s that reach full speed during the cruise portion of their flight home to their final resting place.
 
HT
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 8:13 pm

Quoting PWM2TXLHopper (Reply 4):
I'm sure there have been hundreds of thousands of HR's transported on 747s that reach full speed during the cruise portion of their flight home to their final resting place.

Sorry, I´m not getting the sense of this statement  Confused
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cxsjr
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 9:04 pm

I've still never gotten to grips with the difference between ground speed, air speed, knots, mph etc etc.

If you watch the flight programme on IFE, what does that show your speed in?

I flew back from BOS-LHR on a BA 772 - we flew at FL410 with tail winds of 150+ mph and completed the journey in 5h 40 mins - I'm sure I remember the speed thing on the telly showing 703 mph??!! (BTW, the outward journey on a BA 742 took 8h 15 mins because of the same winds!)

Comments?
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scott0305
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 9:25 pm

Cxsjr - The IFE shows ground speed so the tail (or head) wind component is added to the airspeed to show the actual speed across the ground.
 
eadc8
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 9:30 pm

I once flew LAX - JFK on a FF 747 in 4h 2m. At one point the display showed our ground speed at 718mph. I don't know how that would translate into mach speed, but I would imagine it had to be way up there. Just for the record, the flight was perfectly smooth.
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ikramerica
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 11:01 pm

Quoting EADC8 (Reply 8):

probably just a strong winter wind there. you can get really amazing times in winter to MIA from LAX, too.

But remember, ground speed doesn't equal "mach" speed. Mach speed is the speed of the jet through the air you are in, varies with air density, altitude and wind speed etc. Even if you have a ground speed over still air mach speed at 0 elevation, you are still not traveling faster than the speed of sound in the air around you at 41,000 feet with a 150knot wind, and that's all that matters.
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DLKAPA
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RE: Has Any Body Flown On A 747 At Full Speed?

Sun Aug 07, 2005 11:13 pm

Quoting Cxsjr (Reply 6):
I've still never gotten to grips with the difference between ground speed, air speed, knots, mph etc etc.

Ground Speed: The speed of the aircraft across the earth, the most literal form of "Speed" in that if you were to bounce a radar gun from a stationary object to an aircraft in flight the speed registered would be the aircrafts ground speed.

Air Speed: The actual measurement of speed in flight, measured by the pitot tubes (I think, that or static ports, but I really think its the pitot tubes), actually it measures Ram Air pressure, which is most literally the force of the air molecules as they hit the airplane. If you have a 250 KIAS but a 150kt tail wind, your ground speed will be 400 kts, which brings me to

Knots: A "Knot" is basically One Nautical Mile per hour, and a Nautical Mile is 1 and 1/8th of a statute mile (The form we use).
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UAcsOKC
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 12:50 am

Quoting HT (Reply 5):
Quoting PWM2TXLHopper (Reply 4):
I'm sure there have been hundreds of thousands of HR's transported on 747s that reach full speed during the cruise portion of their flight home to their final resting place.

Sorry, I´m not getting the sense of this statement

Meaning if they cruised at full speed, they'd be dead.
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kc135topboom
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 1:04 am

Cruising in any airplane at it's maximum cruise speed will not ever be noticed by the passengers. The airplane is designed to do that. BTW, ground speed has nothing to do with max mach number. That is a function of the combination of airspeed (even less that max.) and the winds at altitude.

I have flown the KC-135A a lot at maximum mach number (.95M). but most of the time we fly high speed, it is KIAS, as flying mach number means altitude changes. You cannot tell the difference between max cruise and any other cruise speed.

There is something called "high speed buffet" that all airplanes will encounter at or above their designed max airspeed.
 
dstefanc
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 1:13 am

Quoting EADC8 (Reply 8):
At one point the display showed our ground speed at 718mph. I don't know how that would translate into Mach speed, but I would imagine it had to be way up there.

It is very easy for You to check the Mach You were flying at as long as You know what altitude You were flying at. The equation is

M = V / a

where M = Mach,
V = Velocity (in this case 718 mph), and
a = speed of sound

To calculate the speed of sound You can use the following equation:

a = sqrt(gamma * R * T),

where gamma = ratio of specific heats = 1.4 for air
**it's a thermodynamics property
R = universal gas constant
T = surrounding temperature (this value is easy to obtain, because there are published tables of air temperature at each altitude: this is where Your knowledge of the flight level would come in handy). If You know what altitude You were flying at, then that could be translated to what temperature You were flying at. Use this as a source:



So to sum up, the equation is as follows:

M = V / sqrt(gamma * R * T)

**make sure You pay attention to the units, otherwise Your answer won't make sense - by the way, the units have to cancel out, since M is unitless.

Damian
 
dan2002
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 1:15 am

Quoting HT (Reply 5):

Sorry, I´m not getting the sense of this statement Confused

The title of the thread was Any Body Flown on a 747 at full speed. He is talking about human remains, ie bodies being transported below deck. It was a pun.

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CORULEZ05
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 2:11 am

Quoting Dan2002 (Reply 14):
The title of the thread was Any Body Flown on a 747 at full speed. He is talking about human remains, ie bodies being transported below deck. It was a pun.

no he's not.....look at the thread starter:

Quoting 747400sp (Thread starter):
I just wanted to know have anybody ever flown on a 747 during a full power run in flight to confirm this.

He just put a space in the thread topic line but later fixed it in the thread starter.......pretty obvious.
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aeroweanie
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 2:14 am

Quoting DLKAPA (Reply 2):
During the 747 test program, they did high power dives, the airspeed indicators read mach .99, it can be said that parts of the plane (the top of the wing where air moves faster) probably exceeded the sound barrier for a brief period.

In cruise, some regions of a 747 have air traveling faster than the speed of sound (as do most jet airliners). This flow is terminated in shock waves. There is a shock on the wing of the 747 in cruise, a small shock between the nacelle and wing and another in the junction of the horizontal and vertical tail. I have actually seen the first two while traveling on a 747 (I know about the third from CFD work I have done). If the sun is in the right position, you will notice that what you are looking at is split, kind of like looking at something through a clear glass of water, right at the water's edge. This is because you are looking through the shock wave.
 
HT
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 2:55 am

Quoting UAcsOKC (Reply 11):
Meaning if they cruised at full speed, they'd be dead.

&

Quoting Dan2002 (Reply 14):
Quoting HT (Reply 5):
Sorry, I´m not getting the sense of this statement {Confused}

The title of the thread was Any Body Flown on a 747 at full speed. He is talking about human remains, ie bodies being transported below deck. It was a pun.

Tnx for updating me !
I didn´t catch the typing error in "any body" and the subsequent pun built around it by PWM2TXLHopper ...
-HT
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vikkyvik
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 2:58 am

Quoting DLKAPA (Reply 10):
If you have a 250 KIAS but a 150kt tail wind, your ground speed will be 400 kts, which brings me to

Careful there. Ground speed = wind + KTAS (true airspeed), not KIAS (indicated airpseed)

Indicated Airspeed is not the actual speed of the aircraft through the air.

~Vik
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4holer
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 3:08 am

OK, so we've figured out "any body", now lets work on "ruff" and "compacity"!  Wink

My question is if the 747 is the only airliner still flying that you can see the shock wave. I know its cruise speed can be higher than the newer models and maybe the newer jets don't go fast enough for the shock waves?
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IL96M
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 4:02 am

Quoting AeroWeanie (Reply 16):
I have actually seen the first two while traveling on a 747

I have seen this also! So that's what it is...

I also heard that areas around the flight deck windows of the 747 are supesonic too.
 
USAF757300
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 4:20 am

My dad was flying IAD-MUC on a UA T7 and he said that they got up to 692 MPH. It said on the IFE.
 
VS11
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 4:22 am

Quoting 4holer (Reply 19):
OK, so we've figured out "any body", now lets work on "ruff" and "compacity"!

That is hilarious!!!  Smile
 
bhmbaglock
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 6:47 am

Quoting Dstefanc (Reply 13):
Quoting EADC8 (Reply 8):
At one point the display showed our ground speed at 718mph. I don't know how that would translate into Mach speed, but I would imagine it had to be way up there.

It is very easy for You to check the Mach You were flying at as long as You know what altitude You were flying at. The equation is

M = V / a

where M = Mach,

It might also be useful to know the wind at altitude. I'm betting more on high tailwind than high Mach for 718 mph particularly for a W-E route like LAX-JFK.
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Starlionblue
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RE: Has Any Body Flown On A 747 At Full Speed?

Mon Aug 08, 2005 6:51 am

Quoting DLKAPA (Reply 10):

Knots: A "Knot" is basically One Nautical Mile per hour, and a Nautical Mile is 1 and 1/8th of a statute mile (The form we use).

I'm pretty sure the International Nautical Mile is used by all aviation. This is defined as 1852 metres exactly, which converts to 1.150 779 45 statute miles (exactly) or 6 076.115 49 feet (exactly).

For more: http://en.wikipedia.org/wiki/Nautical_mile
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eadc8
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RE: Has Any Body Flown On A 747 At Full Speed?

Tue Aug 09, 2005 8:49 am

Quoting Ikramerica (Reply 9):
probably just a strong winter wind there. you can get really amazing times in winter to MIA from LAX, too.

Yes. It most certainly was. The flight date was 1/29/1996. I should have been a little clearer in my post. I wasn't trying to insinuate that we were flying "balls to the wall". Our ground speed was definitely the result of a very strong tail wind.
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