787-9 video of stunts
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787-9 video of stunts
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Haven't done a side by side comparison, but it seems like a recycle of their 2015 Paris Airshow demonstration.
https://youtu.be/KYbM-3E11Qo
https://youtu.be/KYbM-3E11Qo
I've talked to the pilots in question - a lot of that is tricks with camera angle. While is was a very light airplane at full thrust, he said they never got more than ~45 degrees from straight and level.
Whoopy doo. A few wing waggles. Next!
Tell him he's dreaming. With a thrust-to-weight of what, 0.4 tops? There isn't going to be much verticality unless it's doing 350 knots...
Great head-on videos though.
when you see the ac go vertical
Great head-on videos though.
Last edited by Capn Bloggs; 8th Jul 2016 at 07:01. Reason: I A
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Boeing releases video of 787 stunts not allowed at Farnborough
Not too sure many pilots will watch the video and then lean over to their mate on the next sector and say "Strap in and hold on to your coffee, I saw this awesome video on youtube I want to try and copy."
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Tell him he's dreaming.
https://www.youtube.com/watch?v=EWTK9phKoaE
I actually was at the airshow, and it was far more than 45 degrees.
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NSEU, when I saw the 787, it wasnt the initial rotation, although that was steep, it was when they rolled into the turn, the nose was far more than 30 degrees!
A350 followed suit... https://youtu.be/MPoCPq6mEhk
A350 followed suit... https://youtu.be/MPoCPq6mEhk
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This was photographed from a helicopter on a normal revenue flight.
Boeing 747-446 - Japan Airlines - JAL | Aviation Photo #0640853 | Airliners.net
It's just an optical effect.
For information, that photograph of the 747-400 "ISFD" (3 posts above) was taken with the instrument removed from the instrument panel during maintenance, but not electrically disconnected and gently left hanging down. The symbology is quite interesting at extreme angles.
Boeing 747-446 - Japan Airlines - JAL | Aviation Photo #0640853 | Airliners.net
It's just an optical effect.
For information, that photograph of the 747-400 "ISFD" (3 posts above) was taken with the instrument removed from the instrument panel during maintenance, but not electrically disconnected and gently left hanging down. The symbology is quite interesting at extreme angles.
was taken with the instrument removed from the instrument panel during maintenance
This was photographed from a helicopter on a normal revenue flight.
A350 followed suit...
As I said before: rotate at a high V2, pull the nose up, speed bleeds off then nose starts coming down. Nowhere near vertical.
Boeing stated, after the reaction to the 787-9's display at Farnborough two years ago, that the pitch angle on takeoff was "almost 30 degrees".
Only the most desperate, geometrically-challenged journalist could describe that as "near-vertical".
https://www.youtube.com/watch?v=9oXc08rBy2g
Only the most desperate, geometrically-challenged journalist could describe that as "near-vertical".
https://www.youtube.com/watch?v=9oXc08rBy2g
Folks,
Long time since I have done it, but a light B767-300 (two crew, 15,000 kg fuel) with CF6-80C2 rated at 61,500, using rated thrust followed by full climb thrust needs about 28 degrees pitch up to hold the speed down for the slow flap retraction, and wasn't it good fun.
If you ask most people on the ground, they will tell you 60 degrees of bank is "vertical".
At an airshow, all this it looks a lot more spectacular from the ground than it really is from the picture windows at seats L1 or R1.
Tootle pip!!
Long time since I have done it, but a light B767-300 (two crew, 15,000 kg fuel) with CF6-80C2 rated at 61,500, using rated thrust followed by full climb thrust needs about 28 degrees pitch up to hold the speed down for the slow flap retraction, and wasn't it good fun.
If you ask most people on the ground, they will tell you 60 degrees of bank is "vertical".
At an airshow, all this it looks a lot more spectacular from the ground than it really is from the picture windows at seats L1 or R1.
Tootle pip!!
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Only the most desperate, geometrically-challenged journalist could describe that as "near-vertical".
As the Vietnam Airlines crew kept close tabs on the climb rate, airliner vehicle speed, and "glass cockpit" command bars, the near "S-vertical" takeoff momentarily shifts the Boeing 787-9 in an aggressive flight takeoff performance mode akin to a rocket propulsive system.
Fluidic momentum suggests the near vertical thrust needed to achieve the rapid climb equals a large air intake mass flow through the engines multiplied by an even larger engines' exhaust jet velocity, due to the high vehicle speed of the Boeing 787-9 vertically upward, as seen on the company video.
According to Boeing, the following facts are the conditions for the Boeing 787-9 Dreamliner's near vertical takeoff using either General Electric GEnx-1B or Rolls-Royce Trent 1000 engines: Bypass ratio = 10; Fan diameter = 111-112 inches; Overall pressure ratio = 50; Thrust = 53,000-74,000 pound-feet;
Hence, the near vertical thrust readings on the "glass cockpit" command bar of the Boeing 787-9 airliner is essentially a non-dimensional ratio of two characteristic velocities — one, which is an exhaust jet dependent on how well the engine flow stream is designed, over another, which is a characteristic velocity about 40 percent higher than the speed of sound inside the combustion chambers of the engines.
However, we can also define another figure of merit, called the specific impulse, as directly related to the overall efficiency of the engines of the Boeing 787-9 Dreamliner in performing the near "S-vertical" takeoff. The specific impulse in performing this takeoff is a ratio of the near vertical thrust divided by the temporal rate of change of the Boeing 787-9 weight.
The overall (propulsion system) efficiency may be approximated as a product of the propulsive efficiency and the thermal efficiency. (Note: an engine's overall efficiency measures a ratio of the engine's thrust power (or "useful propulsive work") to available fuel burn energy).
When we take the Boeing 787-9 near vertical takeoff speed, Uo, multiplied by the specific impulse, Isp, we get a measure of the engines' thrust power. The available fuel burn energy is a ratio of the heating value of the fuel, H, to the gravitational constant, g.
Thus, the overall efficiency, Neff, of the Boeing 787-9 Dreamliner, performing as a near vertical takeoff rocket propulsive system, is Neff = (Uo)(Isp) / (H/g).
In summary, these seven (7) performance figures of merit — (1) fuel burn energy, (H/g), (2) specific fuel consumption (SFC) (which measures engine fuel burn efficiency), (3) specific impulse, Isp, (4) engine thermal efficiency, (5) overall (propulsion system) efficiency, Neff, (which is highly dependent upon the closely-monitored airliner's takeoff flight speed and near vertical flight speed, Uo), (6) engine thrust power, (Uo)(Isp), and (7) nitrogen oxide (NOx) emissions (for aero-environmental propulsion engineering design considerations) — are altogether central to the Boeing 787-9 aviation achievements exhibited at the 2015 Paris Air Show on June 15-21, 2015 at Le Bourget Exhibition Centre outside of Paris.
Not a trick, on the ground looked closer to 80 degrees than 30 degrees..everyone around thought something had gone wrong...
Its a simple thrust to weight ratio balance, taking took some queues from the technique of tail walking a fighter jet.
Sorry to disappoint, but really, I did see this aircraft at the airshow, and the initial climb with the nose rolling over was about straight up at that point. The report references screen shots on the glass cockpit from the manoeuvre from Boeing website (these are no longer available)
Bloggs, the 21 degrees that you show was after the roll, and really, 20 degrees is normal, so that is typical.
and the A400 roll? Camera tricks?
https://www.youtube.com/watch?v=fRtOGJTqjkQ
Last edited by underfire; 15th Jul 2016 at 04:34.
I recall reading that at the time it was published in June 2015. It's still as hilarious a year later.
It would be hard to better one of the comments made at the time:
"I'm afraid I have to concur. It's an undecipherable pile of word salad that profoundly obfuscates the salient details. I'm afraid it does not serve as a usable "primer" for the general public to increase their understanding. My conundrum is that this writing was produced by an educator who apparently teaches a class in aviation engineering. I'm curious what the peers in his department think about this piece."
https://www.linkedin.com/pulse/anato...takeoff-oliver
It would be hard to better one of the comments made at the time:
"I'm afraid I have to concur. It's an undecipherable pile of word salad that profoundly obfuscates the salient details. I'm afraid it does not serve as a usable "primer" for the general public to increase their understanding. My conundrum is that this writing was produced by an educator who apparently teaches a class in aviation engineering. I'm curious what the peers in his department think about this piece."
https://www.linkedin.com/pulse/anato...takeoff-oliver