7 ms·

Boeing has flown the 747-8 to Mach .98, within 7 knots of Mach 1

38 points by jlangenauer 16y ago

jacques_chester 16y ago
In fairness, that record was achieved with maximum thrust while descending.
- pkulak 16y ago
  And not even close to the point of the article.
  - sixtofour 16y ago
    But still cool, regardless of how.
- JshWright 16y ago
  They weren't going for a record... They were pushing the aircraft _well_ beyond what it will be experiencing during normal flight operations. It wasn't "Hey, look how fast we can make this thing go." It was "See how far outside the normal operating envelope we can push this before Bad Things® start to happen?"
  - jacques_chester 16y ago
    You're right. It still would have been a moment of diamond-making buttocks, though.
  - sokoloff 16y ago
    It's required by certification standards: 14 CFR 25.335(b) states: (b) Design dive speed, V D. V Dmust be selected so that V C/ M Cis not greater than 0.8 V D/ M D,or so that the minimum speed margin between V C/ M Cand V D/ M Dis the greater of the following values: (1) From an initial condition of stabilized flight at V C/ M C,the airplane is upset, flown for 20 seconds along a flight path 7.5° below the initial path, and then pulled up at a load factor of 1.5 g (0.5 g acceleration increment). The speed increase occurring in this maneuver may be calculated if reliable or conservative aerodynamic data is used. Power as specified in §25.175(b)(1)(iv) is assumed until the pullup is initiated, at which time power reduction and the use of pilot controlled drag devices may be assumed; (2) The minimum speed margin must be enough to provide for atmospheric variations (such as horizontal gusts, and penetration of jet streams and cold fronts) and for instrument errors and airframe production variations. These factors may be considered on a probability basis. The margin at altitude where MCis limited by compressibility effects must not less than 0.07M unless a lower margin is determined using a rational analysis that includes the effects of any automatic systems. In any case, the margin may not be reduced to less than 0.05M. Vc is the maximum operating airspeed and Mc is the maximum operating Mach number. Vd is the dive speed and Md is the dive Mach number. Vc and Mc are called out in an aircraft's Type Certificate Data Sheet. Vd and Md are usually not on the TCDS. So, it's not ham-fisted throttle-jockey joy-riding test pilots, but rather a certification requirement to demonstrate flutter resistance up to the design dive speed.
- byw 16y ago
  It's still impressive that the airframe held up.
ghshephard 16y ago
More interesting in the article was the detail surrounding how Boeing eliminates "Flutter" with an automatic fly-by-wire modal-suppression with a 'software law' - it commands an outboard aileron to basically counteract the flutter out of phase and dampen it out. I couldn't help but think "Autonomic Nervous System" :-)
- icegreentea 16y ago
  Then you'll love every 5th (and many 4th) generation fighter planes. If you watch a F-22 in straight level flight, you can sometimes see subtle twitches in the control surfaces. Makes you kinda warm and fuzzy. It's alive!
  - deleted 16y ago
    [deleted]
  - bl4k 16y ago
    They wouldn't be able to fly without it - they aren't aero stable
dotBen 16y ago
By launching the plane in red rather than blue, Boing clearly sees their future growth market (for this plane at least) as being the Asian countries --- where red is the sign of luck and prosperity. Also, this interested me: The two airlines with orders for the 747-8, Lufthansa and Korean Air, were in Seattle for the unveiling along with private customers for the of the business jet version A private business jet version of the 747-8 -- the world's longest passenger jet? I wonder what that looks like inside and who buys them?
- radicaldreamer 16y ago
  Oligarchs in Russia and the Middle East, perhaps.
- JimmyL 16y ago
  When you click to the second page, it includes "...a representative of Kuwait Airways at the event did confirm...have a 747-8 Intercontinental on order for 'head of state transportation.'"
- tastybites 16y ago
  Air Force One is also based on a 747.
- thematt 16y ago
  Boing clearly sees their future growth market (for this plane at least) as being the Asian countries I just talked to the CEO/President of Boeing the other night and you're absolutely right, that's exactly what their focus is. Not necessarily focused on Asia alone, but most of their sales are international now, particularly to the emerging markets -- and he had no qualms in saying the future of Boeing was outside the United States. A private business jet version of the 747-8 -- the world's longest passenger jet? I wonder what that looks like inside and who buys them? Saudi Princes and other royalty from the Middle East. Often times when they land at Boeing field in Seattle they show off and let people come on-board for tours.
  - bl4k 16y ago
    > Saudi Princes and other royalty from the Middle East. Getting their orders in before their governments fall We hope
RP_Joe 16y ago
Its a great plane. I have flown in all the big jets. The 747 is the best. In a 19 hour flight I would choose it over the new 777.
zck 16y ago
Look how they test the brakes (http://www.wired.com/autopia/2011/02/looking-inside-boeings-new-747/?utm_term=Farzand+Ali&pid=683 http://www.wired.com/autopia/2011/02/looking-inside-boeings-...): >One of the final tests still on the agenda for the 747-8 test pilots is a maximum braking tests. The pilots will abort a take off at approximately 184 knots (212 mph) and come to a stop by standing on the brakes without using thrust reverse devices. The brakes must be at their maximum allowable wear at the time of the test. The brakes are 'pre-worn' a bit in the shop, but most of the work comes down to the pilots to get them ready for the big day. >"We do repeated, abusive landings to wear down the brakes," says test pilot Mark Feuerstein. They slow down from over two hundred miles an hour by standing on the brakes.
- whatusername 16y ago
  Plenty of cars can do that. Of course -- I don't think there's too many vehicle's on land with the momentum of a 747 at 320km/h. And definately not many that can compare on a momentum:surface friction ratio.
otto 16y ago
Without altitude and temperature a Mach number is rather useless. (Depending on altitude the temperature and pressure changes which has an effect on the speed of sound.) Also was this just the Mach experienced at the leading edge?
- Nick_C 16y ago
  >Without altitude and temperature a Mach number is rather useless Actually, no, it's the most important number. See http://womanpilot.com/?p=61 http://womanpilot.com/?p=61 (near the end) for why.

38 points by jlangenauer 16y ago

jacques_chester 16y ago

In fairness, that record was achieved with maximum thrust while descending.

pkulak 16y ago
And not even close to the point of the article.
- sixtofour 16y ago
  But still cool, regardless of how.
JshWright 16y ago
They weren't going for a record... They were pushing the aircraft _well_ beyond what it will be experiencing during normal flight operations. It wasn't "Hey, look how fast we can make this thing go." It was "See how far outside the normal operating envelope we can push this before Bad Things® start to happen?"
- jacques_chester 16y ago
  You're right. It still would have been a moment of diamond-making buttocks, though.
- sokoloff 16y ago
  It's required by certification standards: 14 CFR 25.335(b) states: (b) Design dive speed, V D. V Dmust be selected so that V C/ M Cis not greater than 0.8 V D/ M D,or so that the minimum speed margin between V C/ M Cand V D/ M Dis the greater of the following values: (1) From an initial condition of stabilized flight at V C/ M C,the airplane is upset, flown for 20 seconds along a flight path 7.5° below the initial path, and then pulled up at a load factor of 1.5 g (0.5 g acceleration increment). The speed increase occurring in this maneuver may be calculated if reliable or conservative aerodynamic data is used. Power as specified in §25.175(b)(1)(iv) is assumed until the pullup is initiated, at which time power reduction and the use of pilot controlled drag devices may be assumed; (2) The minimum speed margin must be enough to provide for atmospheric variations (such as horizontal gusts, and penetration of jet streams and cold fronts) and for instrument errors and airframe production variations. These factors may be considered on a probability basis. The margin at altitude where MCis limited by compressibility effects must not less than 0.07M unless a lower margin is determined using a rational analysis that includes the effects of any automatic systems. In any case, the margin may not be reduced to less than 0.05M. Vc is the maximum operating airspeed and Mc is the maximum operating Mach number. Vd is the dive speed and Md is the dive Mach number. Vc and Mc are called out in an aircraft's Type Certificate Data Sheet. Vd and Md are usually not on the TCDS. So, it's not ham-fisted throttle-jockey joy-riding test pilots, but rather a certification requirement to demonstrate flutter resistance up to the design dive speed.
byw 16y ago
It's still impressive that the airframe held up.

ghshephard 16y ago

More interesting in the article was the detail surrounding how Boeing eliminates "Flutter" with an automatic fly-by-wire modal-suppression with a 'software law' - it commands an outboard aileron to basically counteract the flutter out of phase and dampen it out. I couldn't help but think "Autonomic Nervous System" :-)

icegreentea 16y ago
Then you'll love every 5th (and many 4th) generation fighter planes. If you watch a F-22 in straight level flight, you can sometimes see subtle twitches in the control surfaces. Makes you kinda warm and fuzzy. It's alive!
- deleted 16y ago
  [deleted]
- bl4k 16y ago
  They wouldn't be able to fly without it - they aren't aero stable

dotBen 16y ago

By launching the plane in red rather than blue, Boing clearly sees their future growth market (for this plane at least) as being the Asian countries --- where red is the sign of luck and prosperity. Also, this interested me: The two airlines with orders for the 747-8, Lufthansa and Korean Air, were in Seattle for the unveiling along with private customers for the of the business jet version A private business jet version of the 747-8 -- the world's longest passenger jet? I wonder what that looks like inside and who buys them?

radicaldreamer 16y ago
Oligarchs in Russia and the Middle East, perhaps.
JimmyL 16y ago
When you click to the second page, it includes "...a representative of Kuwait Airways at the event did confirm...have a 747-8 Intercontinental on order for 'head of state transportation.'"
tastybites 16y ago
Air Force One is also based on a 747.
thematt 16y ago
Boing clearly sees their future growth market (for this plane at least) as being the Asian countries I just talked to the CEO/President of Boeing the other night and you're absolutely right, that's exactly what their focus is. Not necessarily focused on Asia alone, but most of their sales are international now, particularly to the emerging markets -- and he had no qualms in saying the future of Boeing was outside the United States. A private business jet version of the 747-8 -- the world's longest passenger jet? I wonder what that looks like inside and who buys them? Saudi Princes and other royalty from the Middle East. Often times when they land at Boeing field in Seattle they show off and let people come on-board for tours.
- bl4k 16y ago
  > Saudi Princes and other royalty from the Middle East. Getting their orders in before their governments fall We hope

RP_Joe 16y ago

Its a great plane. I have flown in all the big jets. The 747 is the best. In a 19 hour flight I would choose it over the new 777.

zck 16y ago

Look how they test the brakes (http://www.wired.com/autopia/2011/02/looking-inside-boeings-new-747/?utm_term=Farzand+Ali&pid=683 http://www.wired.com/autopia/2011/02/looking-inside-boeings-...): >One of the final tests still on the agenda for the 747-8 test pilots is a maximum braking tests. The pilots will abort a take off at approximately 184 knots (212 mph) and come to a stop by standing on the brakes without using thrust reverse devices. The brakes must be at their maximum allowable wear at the time of the test. The brakes are 'pre-worn' a bit in the shop, but most of the work comes down to the pilots to get them ready for the big day. >"We do repeated, abusive landings to wear down the brakes," says test pilot Mark Feuerstein. They slow down from over two hundred miles an hour by standing on the brakes.

whatusername 16y ago
Plenty of cars can do that. Of course -- I don't think there's too many vehicle's on land with the momentum of a 747 at 320km/h. And definately not many that can compare on a momentum:surface friction ratio.

otto 16y ago

Without altitude and temperature a Mach number is rather useless. (Depending on altitude the temperature and pressure changes which has an effect on the speed of sound.) Also was this just the Mach experienced at the leading edge?

Nick_C 16y ago
>Without altitude and temperature a Mach number is rather useless Actually, no, it's the most important number. See http://womanpilot.com/?p=61 http://womanpilot.com/?p=61 (near the end) for why.