Posted on 11/16/2001 1:19:06 PM PST by The Magical Mischief Tour
This is Bull $h!t!!!
The NTSB is LYING like rugs!!!
NTSB dude just claimed that .3 to .8 g's encountered during the wake encounter caused the Airbus to break up in flight...
Even a male reported asked "is this even possible".
"Isn't this normal bumping encountered when flying?"
Even the media don't believe them!!!!!
No, you or the other poster have got the reported winds just backwards -- they were 11 kts @ 320, meaning out of the northwest, almost down the rwy centerline. Had they been from the southeast, then they would have been departing using rwy 13, into the wind.
Probably something like that, but that would be in the longitudnal plane, ie "up and down" in the aircraft's own axes. Lateral rating is probably somewhat less I would think, since one doesn't normal skid to turn, although it can be done.
Maybe if you stomped on the rudder at 450mph, maybe. However you don't turn an aircraft that way. You do turn most missles that way, it's called skid to turn. With an aircraft, and some missles, cruises for example, you bank the beast to turn it. That way you use the lift force from the wings, i.e. positive Gs in the Up direction of the aircraft, rather than side force, which is hard to generate with that little bitty rudder, and hard on that rudder too. When you bank to turn, you use the rudder to keep the turn "coordinated", that is to minimize those side forces, which just cause more drag, which you don't want. You must also pull back on the stick or yoke, to increase the angle of attack so as to produce the extra lift force that you need to drag yourself around the turn, while still retaining enough of a verticle (earth axis not aircraft axis) component to hold the airplane up against gravity. For example a 45 degree banked turn requires the aircraft to pull 1.414 (sqaure root of 2) G's parrallel to your spine, to keep the aircraft flying level, but turning. You'd get one "G" of "force" vertically and one horizontally. That one "G" of "force" would cause you to turn about 2.8 degrees per second at 450 mph. At a lower speed the same accelleration would be produce a faster turn rate, because the turn rate is inverserly proprotional to the speed and directly proportional to the horizontal accelleration.
psi-dot = 180/Pi * A / V
where psi-dot is the turn rate in degrees per second. A is the accelleratin and V is the speed. Speed and accelleration must be in compatible units, such as ft/sec/sec and ft/sec or meters/sec/sec and meters/second. The turn rate comes out in degrees per unit time, if you want to use some other measure of time, minutes, hours, days or fortnights. Leave off the 180/Pi if you want the rate in radians per second.
Never try to do engineering calculations with furlongs as the measure of length and fornights as the measure of time. You'd be sure to blow a gasket somewhere along the way, and your bridge would surely fall or your airplane crash. :).
Modern aircraft are equiped to measure both accellerations and angular rates. It's how they navigate, along with GPS, Loran or other external navaid, if available. The measurements are also used in the flight control system and/or the autopilot. The FDR merely records these measurements, often at a somewhat slower rate than the navigation systems generates and uses them. Accellerations are measured, not surprisingly, by accellerometers but angle rates are measured by rate gyros (gyroscopes). You need three of each (at least) so as to measure the accellerations in or turn rates about 3 mutual perpindicular directions.
All true, but your referents are usually pulled in the vertical direction, that is perpendicular to the wings, not sideways. If you pulled 0.5 g's sidewise, you'd likely fall over into the lap of the person in the next seat, you'd at least lean that way a signifigent amount.
those are measured normal to the wings, not sideways. I have no idea what the sideways values might be, but I'll be they are less. Wouldn't want to spill anybody's drinks you know.
First off, I build airplanes for Boeing. They are not bolts per say, but hilocks or hilites with collars, and yes the collars could be loosened a little bit, but I doubt that that would cause the tail section and both engines to fall off in such a short flight.
Second, the tail section seems to have fallen off first ahead of any other parts, this would lead me to believe 2 things, a. the flight would have continued on the path that it previously had taken (going up, not down) and b. the amount of time it would have taken to loosen that many bolts in that small of space and in that short of time would be impossible. (Try putting together a tail section of an airplane, there is barely room for one much less 2 or more people even on a jumbo jet.) And it takes a lot of time to loosen or tighten that many collars even with Pneumatic equipment and you would have to have all of the proper equipment at that. This would mean various Knar and the like guns for the location and difficulty and length of the collars.
That said, I wondered about something much simpler and faster, acid on the skins themselves. Other than that or a bomb, missle, etc, I simply can not see pure mechanical failure without some very, very, very, very, lacks maintenence, and AA is not known for that.
The NTSB's job is TO PROVE WHY ITS SAFE TO FLY.
If they need help, the FBI and CIA are there to assist. The real potential of a catastrophic economic collapse due to airliners falling from the sky is a matter of NATIONAL SECURITY.
Truth is always sacrificed in the name of National Security.
That's the answer to this and future airliner 'accidents'.
If you went water skiing behind a boat you'd have problems when passing over the wakes because they would make you jump up and tilt. That jump and tilt makes your legs bend and twist, so much so they can give in and you fall. This jump is a force, and a force is, grossly speaking, an acceleration, and we measure the acceleration in terms of gravity. When you stand up on your skis, your feet experience 1 g of earth gravity verticaly and 0gs latteraly. When you hit the wake and jump up you may get up to 1.3 or even 2 vertical gs. Since you hit the wake at an angle, you will tilt because of a latteral force. Hence you will get .3 to .8gs latteraly too.
So an airplane encountering another airplane's wake will get bumped around, much like when a boat or water skier encounters the wake of another boat ahead. Boats have jumped up and broken apart that way at high speed, and so can airplanes. But that is only if the airplane following comes in at really high speed. A latteral wake of .3 to .8gs is really minimal and should not break an airplane apart. In addition it's not the whole vertical tail section that fell, it is the hinged vertical steerring stabilator.
It's possible that flutter was a factor. Only violent flutter of the hinged section of the tail can cause it to fall. That happens when the airplane loses counterweights in the tail. Counterweights affect the mass distribution of the tail in such a way that it heavily dampens any flutter. But usualy flutter happens at higher speeds. So this is all a mystery to me.
Note that we cannot have evidence of wake turbulence except for circumstancial clues such as another airplane ahead and data recorders indicating accelerations. But vortices are invisible except in rain or snow. In this case you can see them a bit. Accelerations like these recorded in the airplane can be due to pilot input, violent flutter imitating nature and other factors. They could be things other than turbulence.
1. If tail fin fell off, big piece, why did nobody see it fall before engines explode. If you saw a wide bodied jet without a tail fin I guess you might notice.
2. Presumably the tail fin will drop slower and may even "fly" as it descends, a one ton engine would I guess go straight down. As would the fuselage.
How about this
Left engine explodes, plane lurches and down left, goes in spin, tail ripped off, engines fall followed by fuselage. Who says rudder / tail came off first?
Another puzzle, why no contact with Air Traffic Control, if only to scream Holy sheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeet on the way down. "Houston we have a problem"
Oh gawd... Don't tell me you are one of those bimbos zipping in and out of traffic I so very much love blocking with my Suburban and out accelerating with same. :)
Actually I spent many years (of fun and thrills) driving in excess of 1g. 'Blueflag' is a racing moniker.
For grins and information I used to drive around with a 2-axis accelerometer / g-force analyzer attached to my car to practice driving smoothly while driving quickly. It illustrated that even in, ahem, well-executed, spririted street driving, you seldom broke .8 Gs and usually were in the .3 - .5 range.
Truth is nowadays I am very calm in traffic-- got the juices out on the track.
Having stated that, if you cut me off in your Suburban, I'd roll over you in my F-350 ... (I'll see your 4 tons and raise you 2!!
Just kidding-- I drive a Lincoln LS 5 sp. 8-)
Again, not trying to flame, but the expression "force of 1 g" is not physically correct. In engineering, terms such as "force" and "acceleration" have rigorous definitions.
It's perfectly analogous to saying that a wire has a "resistance" of 0.3 Volts. Sure, with the known equation, V=IR, and given I, you can find R easy enough. Similarly, Newton tells us that F=MA. You're giving me A and calling it F.
For most engineering calculations, the space-based terms (position, velocity, accel) are given with respect to some "fixed" body. In this case, it's the ground, and my original statement is correct.
Why not "Blackflag?" :)
When I was in college, I spent a great deal of time at local autocrosses, which got me interested in vehicle dynamics. I was also a team member of the university's first Formula SAE design team, but alas, I had to graduate and get a real job. I miss those days.
For grins and information I used to drive around with a 2-axis accelerometer / g-force analyzer attached to my car to practice driving smoothly while driving quickly. It illustrated that even in, ahem, well-executed, spririted street driving, you seldom broke .8 Gs and usually were in the .3 - .5 range.
Yep. The only way most cars can exceed 0.8 g is under braking. Some good sports cars can exceed it under cornering, and few very powerful AWD cars (911 Turbo)can approach 1g under straight-line acceleration for a second or so.
Above about 0.5g would have most "normal" folks with white knuckles and tossing their cookies.
Just kidding-- I drive a Lincoln LS 5 sp. 8-)
Nice car...too bad they don't offer the V8 with the 5 spd. Maybe they will someday soon.
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