National 747 crash
05-17-2013, 05:21 AM
#128
RE: National 747 crash
Dave,
Once past V1 you take your troubles airborn because most likely you can no longer stop without launching off the end of the runway.
Take off power settings are calculated on just enough for you to either lose an engine at V1 and stop or be at 35' at the end of the runway. It's called balanced field. Past V1 and abort and you over run. I think the percentage of high speed RTOs past V1 that end up off the runway is in the neighborhood of 90 percent. Typically in a training environment if you abort past V1 on a check ride it's a bust.
Beave
Once past V1 you take your troubles airborn because most likely you can no longer stop without launching off the end of the runway.
Take off power settings are calculated on just enough for you to either lose an engine at V1 and stop or be at 35' at the end of the runway. It's called balanced field. Past V1 and abort and you over run. I think the percentage of high speed RTOs past V1 that end up off the runway is in the neighborhood of 90 percent. Typically in a training environment if you abort past V1 on a check ride it's a bust.
Beave
ORIGINAL: FalconWings
Boli what happens if V2 is called on takeoff roll and then **** hits the fan......do you commit to takeoff or is aborting the takeoff even an option at that point?
Boli what happens if V2 is called on takeoff roll and then **** hits the fan......do you commit to takeoff or is aborting the takeoff even an option at that point?
05-17-2013, 06:22 AM
#129
RE: National 747 crash
ORIGINAL: alasdair
The only jet transport I have come across with a stick push was the HS Trident.
ORIGINAL: bevar
Glenn,
FYI...a stick shaker just shakes the yoke...it does not move it. You are thinking of a stick pusher which most large and heavy jets do not have. That being said, I don't have any time in the -400 so maybe it does have one.
Beave
Glenn,
FYI...a stick shaker just shakes the yoke...it does not move it. You are thinking of a stick pusher which most large and heavy jets do not have. That being said, I don't have any time in the -400 so maybe it does have one.
Beave
But, they are not "heavy" jets, in the regulations-defined sense of the word...just a little light-twin flying, as major airliners go
Sluggo
05-17-2013, 06:49 AM
#133
RE: National 747 crash
ORIGINAL: rhklenke
Computers... [:-]
ORIGINAL: VF84sluggo
...LOL!
Hey, don't knock it...Boeing might build airplanes, but McDonnell-Douglas builds character!! (and Lockheed builds systems
)
Still haven't quite figured out what Airbus builds...
Sluggo
...LOL!Hey, don't knock it...Boeing might build airplanes, but McDonnell-Douglas builds character!! (and Lockheed builds systems
)Still haven't quite figured out what Airbus builds...
Sluggo
Computers... [:-]
05-17-2013, 07:25 AM
#134
RE: National 747 crash
ORIGINAL: David Gladwin
Alasdair, as well as the Trident the VC10 also had a pusher, T-tail being the common aspect, but all three Boeing types I have flown were shakers only. After the Trident and 1-11 deep stall accidents I was a little anxious when on BOAC VC10 stall training we went as far as the pusher, and in the aircraft, not the sim. !
Alasdair, as well as the Trident the VC10 also had a pusher, T-tail being the common aspect, but all three Boeing types I have flown were shakers only. After the Trident and 1-11 deep stall accidents I was a little anxious when on BOAC VC10 stall training we went as far as the pusher, and in the aircraft, not the sim. !
I do not remember whether we took the Trident to the stick-push, or just the shaker, on base training.
from what Sluggo says the Douglas T-tail had a pusher too.
Anyone know about the Boeing 727? pusher or just shaker?
Has anyone built a model of a T-tail jet transporter? Do they suffer deep stall like th full size?
05-17-2013, 07:46 AM
#136
RE: National 747 crash
It is most likely a "T-tail" device, as a deep stall is to be avoided at all costs. It's possible for the disrupted wake of the wing in a fully developed stall to blank the horizontal stab/elevator, making recovery impossible.
Sluggo
Sluggo
05-17-2013, 08:54 AM
#139
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RE: National 747 crash
Not transport category, but the Merlins were nicknamed 'death tube' due in part to their poor low-speed handling characteristics. Cruciform tail, full-flying stab with no mechanical trim wheel, just dual electric jackscrew actuators. SAS (stability augmentation system) with a stick pusher consisting of a fixed (25 lb IIRC) weight ahead of the yoke that is electronically 'removed' near the stall, pulling the yoke forward.
My old ride.
Very clean stall, very little/no buffet, airplane just drops. Unusual single-engine behavior, to say the least.
My old ride.
05-17-2013, 06:08 PM
#142
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RE: National 747 crash
ORIGINAL: willig10
You would be correct if this was a pure jet. The engine is a split spool engine and the 3rd stage wheel drives the compressor. The compressors 1st stage is the fan. It is the fan that provides around 90% of the thrust. The other 10% come out of the exhaust cone. Another way of determining a high bypass engine is in it,s thrust reversing system. A pure jet will have clam shell doors that are mounted on the aft end of the engine and when activated they cover the exhaust and divert the exhaust/thrust forward. On a high bypass engine the thrust reversed is mounted on the aft end of the inlet. This is called a cascade reversed and it diverts the fans thrust forward. This is because,smoke? the majority of
the thrust is in the 1st stage fan/compressor.
Glenn Williams
You would be correct if this was a pure jet. The engine is a split spool engine and the 3rd stage wheel drives the compressor. The compressors 1st stage is the fan. It is the fan that provides around 90% of the thrust. The other 10% come out of the exhaust cone. Another way of determining a high bypass engine is in it,s thrust reversing system. A pure jet will have clam shell doors that are mounted on the aft end of the engine and when activated they cover the exhaust and divert the exhaust/thrust forward. On a high bypass engine the thrust reversed is mounted on the aft end of the inlet. This is called a cascade reversed and it diverts the fans thrust forward. This is because,smoke? the majority of
the thrust is in the 1st stage fan/compressor.
Glenn Williams
So the thrust reverser system determines whether it's a high or low bypass engine................. Uh, never mind, not worth it.
05-17-2013, 08:30 PM
#143
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RE: National 747 crash
So the thrust reverser system determines whether it's a high or low bypass engine................. Uh, never mind, not worth it.
Uhh, ..., its actually just the opposite. Just so you know...,
05-17-2013, 09:39 PM
#144
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RE: National 747 crash
stupid question as I am only guessing but could the fuel have been pumped to the wrong tanks, like the back ones? IDK? someone said the plane was at the base to re-fuel only. Isn't the fuel a calculation in the balance of the plane?
Chad
Chad
05-17-2013, 10:40 PM
#145
RE: National 747 crash
The MadDog and Diesel 9 are born of Douglas so they don't truly follow Boeing design lineage.
More to the point, rumor has it that the CVR and FDR lost signal input during takeoff. Unfortunately it's likely that one of the 40,000 to 70,000 pound vehicles they were taking to DXB broke through the aft pressure bulkhead and took out all kinds of stuff.
Unfortunately we may never know what really happened. A high price for a lesson not learned.
BTW, Boeing's recovery from nose high unusual attitude is a roll toward knife edge, letting the nose fall to the horizon then to pull out from the slight dive with wings level.
The Vapor I suspect was fuel dump.
The gear being extended in their last moments was a last ditch effort to try and absorb some energy from the impact.
And for the record, none of the four Swept wing Boeing types I've flown ever pitched up on the way to a full stall as was mentioned earlier. Some airplanes do have that issue but not Boeing. They simply wouldn't pass part 25 certification for transport category aircraft.
More to the point, rumor has it that the CVR and FDR lost signal input during takeoff. Unfortunately it's likely that one of the 40,000 to 70,000 pound vehicles they were taking to DXB broke through the aft pressure bulkhead and took out all kinds of stuff.
Unfortunately we may never know what really happened. A high price for a lesson not learned.
BTW, Boeing's recovery from nose high unusual attitude is a roll toward knife edge, letting the nose fall to the horizon then to pull out from the slight dive with wings level.
The Vapor I suspect was fuel dump.
The gear being extended in their last moments was a last ditch effort to try and absorb some energy from the impact.
And for the record, none of the four Swept wing Boeing types I've flown ever pitched up on the way to a full stall as was mentioned earlier. Some airplanes do have that issue but not Boeing. They simply wouldn't pass part 25 certification for transport category aircraft.
05-18-2013, 01:26 AM
#148
RE: National 747 crash
ORIGINAL: chadxp1
stupid question as I am only guessing but could the fuel have been pumped to the wrong tanks, like the back ones? IDK? someone said the plane was at the base to re-fuel only. Isn't the fuel a calculation in the balance of the plane?
Chad
stupid question as I am only guessing but could the fuel have been pumped to the wrong tanks, like the back ones? IDK? someone said the plane was at the base to re-fuel only. Isn't the fuel a calculation in the balance of the plane?
Chad
Only used as a last resort, last to get filled and first to empty IIRC.
If they filled that one by mistake on a short or medium haul flightit could spoil your day, but would be bound to be noticed.
05-18-2013, 02:10 AM
#149
RE: National 747 crash
Apparently not, but I am well aware of it when flying!
This is what happens Alasdair, this idiot attempted a loop with the gear down-WRONG!!!!
http://www.youtube.com/watch?v=c4Yl8jUut2k
This is what happens Alasdair, this idiot attempted a loop with the gear down-WRONG!!!!
http://www.youtube.com/watch?v=c4Yl8jUut2k
05-18-2013, 10:36 AM
#150
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RE: National 747 crash
Yep, San Antonio Sewer Pipe lol.
I believe the gear was deployed throughout. The last thing I'd be doing is jerkin' the gear during an emergency.
Accident investigators do amazing reconstruction forensics. Let's see what they say. It will take several months.