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New FDR Decode

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posted on Dec, 10 2009 @ 05:43 PM
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off-topic post removed to prevent thread-drift


 




posted on Dec, 10 2009 @ 07:16 PM
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Originally posted by thomk
I disagree. I am sure that the vert/lat/long acceleration data is pure data pulled out of the accelerometers that are simply mounted on orthogonal axes that match the planes major axes.

I found some evidence for that in the FDR data itself.

There were two extended stretches of level cruise on
autopilot, at 35,000 and 25,000 feet. The average
pitch angles for those two stretches imply about
1.0 ft/sec of longitudinal acceleration from gravity,
provided the longitudinal accelerometer is mounted in
line with the plane's major axis and is not corrected
for pitch. The average longitudinal acceleration
recorded during those two stretches was about 1.28
ft/sec. Although there was a slight increase in
airspeed during both stretches, there was nowhere
near as much increase as implied by the extra 0.3
ft/sec.

It looks to me like a small error in alignment
(less than one degree) combined with the effect of
gravity. I can't yet tell how much of the error is
in the pitch angle versus the error in the alignment
of the longitudinal accelerometer.

I can easily believe that these (and other) small
errors in the pitch angle and accelerometer alignment
are the real reason I'm getting a better fit to the
altitude data for the final seconds when I assume
accelerations were measured with respect to the
direction of motion instead of the aircraft's axes.

I'm going to estimate the systematic errors as best
I can from calculations such as the above, and see
what the calculations look like when correcting for
those errors. The fit will never be perfect, and
I think I'm getting close to over-interpreting the
noise.

Will



posted on Dec, 10 2009 @ 07:26 PM
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reply to post by JFrickenK
 


Of course they don`t, and they never will match. The calculator in question assumes a coordinated turn, made smoothly. As well as not taking into account atmospheric conditions. The turn in real life was horribly uncoordinated, and anything but smooth.



posted on Dec, 10 2009 @ 07:45 PM
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Originally posted by Zaphod58
reply to post by JFrickenK
 


Of course they don`t, and they never will match. The calculator in question assumes a coordinated turn, made smoothly. As well as not taking into account atmospheric conditions. The turn in real life was horribly uncoordinated, and anything but smooth.


OK, But can you get from point 7 to 15 on my plot using that calculator disregarding the actual jerks and bumps and still fit within the time parameter ?

I can not.

If it can not be done with a coordinated turn, how can it be done with an uncoordinated turn ?

Do you understand my question ?

Edit to add - Start at point 7, disregard all real world points from there until point 15, and assume a coordinated turn between points 7 and 15 which is roughly 180 degrees.

The calculator says that can not be done.


[edit on 10-12-2009 by JFrickenK]



posted on Dec, 10 2009 @ 08:16 PM
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9/11 MADNESS
post removed because of personal attacks

Click here to learn more about this warning.



posted on Dec, 10 2009 @ 08:24 PM
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I graphed that final turn a while back from the csv file and came up with an average airspeed 284 knots, average bank angle 26.4 degrees, turn diameter around 5-6 statute miles (it's not a perfect circle) and the elapsed time about 3 minutes.



The units are in statute miles referenced to the Pentagon point of impact.

When I plug the entry airspeed of 286 knots and average bank angle into the calculator I get virtually identical results. It also tells me the stall speed is increased by a factor of only 1.1 plus the G load is only 1.1G (quite comfortable).

The calculator confirms the FDR data quite well doesn't it?

[edit on 10/12/2009 by Pilgrum]



posted on Dec, 10 2009 @ 08:25 PM
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reply to post by Reheat
 


I asked you 18 months ago and you decided to hinder my every move.

It is too late for you to be replying to my question.

Bye reheat.

< add to ignore list >



posted on Dec, 10 2009 @ 08:28 PM
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Originally posted by JFrickenK
Edit to add - Start at point 7, disregard all real world points from there until point 15, and assume a coordinated turn between points 7 and 15 which is roughly 180 degrees.

The calculator says that can not be done.


If you think this turn can not be accomplished then how in the HADES do you support your children that have posted truly impossible turns (over and over again) that are of infinitely greater speed, bank angle, and turn radius than this rather gentle easy turn?

Have you reached the bottom of your hole yet?



posted on Dec, 10 2009 @ 08:35 PM
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Originally posted by JFrickenK
reply to post by Reheat
 


I asked you 18 months ago and you decided to hinder my every move.

It is too late for you to be replying to my question.

Bye reheat.

< add to ignore list >


You used your BAN hammer before I had a chance to reply. I corrected your wrong stall speed. What else do you expect from a JREF "clown"? Correct answers?


ETA: Do you feel powerless without your arbitrary BAN hammer, JFK?


[edit on 10-12-2009 by Reheat]



posted on Dec, 10 2009 @ 09:23 PM
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Will,


Originally posted by thomk
I disagree. I am sure that the vert/lat/long acceleration data is pure data pulled out of the accelerometers that are simply mounted on orthogonal axes that match the planes major axes.



Originally posted by cesura
That was my original opinion too, but it looks as though I was wrong. I could be wrong about having been wrong, however.


LoL. Yeah, we all get onto that roller coaster periodically.

___


Originally posted by thomk
You'll see that each time the plane climbs, the longitudinal accel shows an increase that is proportional to the steepness of the climb. You're simply getting a "sensor weight" component that is adding into its recorded value. (Obviously it's not a real long. accel, since the plane linear velocity will slow down with constant thrust in a climb.)



Originally posted by cesura
That will happen if the accelerations are aligned with respect to the plane's direction of motion, and it will also happen if the accelerations are aligned with the plane's axes. (The only plausible way it wouldn't happen is if the accelerations are aligned with the earth, which clearly isn't what was done. I suspect you thought I was arguing for that interpretation.)


True. But the reality is that they simply bolt the accelerometers onto the plane.


Originally posted by cesura
Recall that, to a first approximation, fixed wing aircraft tend to fly in the direction they're pointed. That means the differences between alignment with the direction of motion and alignment with respect to the aircraft's axes are pretty small.


As you know, planes skid thru the air, so that can be a poor approximation. Especially if the pilot is jerking around on the yoke & ignoring the rudders (as Hanjour appeared to be doing). The thing working in your favor was his speed & the fact that the plane was clean (no flaps, gear, etc.)

The military does exactly what you are trying to do for its fighter jets. It takes all the plane's state data (velocities, accelerations in all axes) plus all control inputs, plus a huge database of empirical performance in all flight envelopes, and calculates a "velocity vector" that it displays on the HUD. As I understand it, it ain't a trivial problem.

Depending on how deep you want to go, you might want to look up a "physics based" flight sim program called X-Planes. [www.x-plane.org] They've got 757-200 models already built. If you really want to get into looking at flight paths, accelerations, roll, pitch & yaw, etc. It might be informative to input the controls & watch the flight path. It ain't a full up validated sim, of course, but it could probably give you a "reality check" on your own modeling.

I know the software has been used by several companies (including, IIRC, Scaled Composites) to help with the development of prototype aircraft. It won't be exact, but it ought to be close. And you ought to be able to independently confirm your flight path data by inputting control. I wouldn't be surprised if someone hasn't already done this for AA77.

Just a thought...

tom



posted on Dec, 10 2009 @ 09:34 PM
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reply to post by Pilgrum
 


OK I see what I did wrong...

For some reason I was trying to keep increased stall speed below rated stall speed.
( have no clue why )

Even with "my error" which reheat quickly jumped upon ( perhaps that is why ? ) 18 months ago without telling me what it actually was ( I had the rated stall speed in the MPH column instead of the KTS column ) It would still be able to do it with with 109+ KTS to spare...

I Redact the claim.



posted on Dec, 10 2009 @ 09:50 PM
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Originally posted by JFrickenK

Edit to add - I also guess you missed what I posted in THIS post regarding your "square corners" 18 months ago.


[edit on 10-12-2009 by JFrickenK]



LMFAO...

Thanks for posting that, JFK. Best laugh I've had in awhile.

Are you really, REALLY proud of those tables of numbers, JFK?

32 significant figures, eh...??? WHILE calculating the chord length instead of the arc length...??

You did your "calculations" (nah, just plug in stupidly & grind) "assuming a level flight path", didja?

Thanks for proving that you haven't the SLIGHTEST fluency with numbers or calculations.

There is not one competent engineer or physicist in the world who would not take one look at that page and start laughing.

Thanks. I needed that.

TomK



posted on Dec, 10 2009 @ 10:17 PM
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Originally posted by JFrickenK

And no, the angle of the radii between the 12 second sweeps does not precisely fit the calculator options of 90, 180, and 360 degrees.. It doesn't even come close.

[edit on 10-12-2009 by JFrickenK]



You've got absolutely NO IDEA what this calculator is for, or how to use it properly, do you, JFK.

LoL.


TomK



posted on Dec, 10 2009 @ 10:21 PM
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Originally posted by JFrickenK
reply to post by Pilgrum
 


OK I see what I did wrong...

For some reason I was trying to keep increased stall speed below rated stall speed.
( have no clue why )


This doesn't make sense and you still don't get it.


Originally posted by JFrickenK
Even with "my error" which reheat quickly jumped upon ( perhaps that is why ? ) 18 months ago without telling me what it actually was ( I had the rated stall speed in the MPH column instead of the KTS column ) It would still be able to do it with with 109+ KTS to spare...


I told you *specifically* about that error 18 months ago. AND that's not your only mistake as you read Tom's post below. I seriously doubt you'll understand even after reading that.


Originally posted by JFrickenK
I Redact the claim.


Not good enough.



posted on Dec, 10 2009 @ 11:09 PM
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Originally posted by JFrickenK
reply to post by Pilgrum
 


OK I see what I did wrong...

...

I Redact the claim.

Gee, are we going to have to wait another 18 months for you to retract your other stupid claims?

And how many times have you boldly asserted that the plane would fall out of the sky in that entire length of time?

Oh that's rich, it's Reheat's fault for failing to teach you how to perform a calculation correctly, yet you wear no fault for being so confident in your own abilities that you didn't bother to have someone of authority peer review your work before making repeated bold assertions that the physics were impossible!

You're hilarious, JFK, and much more fun when you can't pull out the ban hammer as you so frequently do elsewhere.



posted on Dec, 10 2009 @ 11:16 PM
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Originally posted by JFrickenK
reply to post by Pilgrum
 

I Redact the claim.

Ooh he's going to redact, not retract, his woefully informed claim.

Freudian slip, JFK?



posted on Dec, 10 2009 @ 11:33 PM
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reply to post by JFrickenK
 


Unless the increased stall speed is somewhere north of 250 knots it's not likely that the plane will stall in that turn. The calculator predicts stall speed will be 10% higher in that turn.

Just to save me looking it up, what is the rated stall speed for a 757?



posted on Dec, 10 2009 @ 11:43 PM
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Originally posted by Pilgrum
reply to post by JFrickenK
 


Unless the increased stall speed is somewhere north of 250 knots it's not likely that the plane will stall in that turn. The calculator predicts stall speed will be 10% higher in that turn.

Just to save me looking it up, what is the rated stall speed for a 757?



Okay, seeing as how there are written statements by the IAD controllers, and DCA audio describing the turn as it happened, a C-130 pilot who saw the plane during the turn and decribed the bank angle, I'm not sure what the point of this discussion is. Is JFK asserting that not only the RADES and ASR data is wrong, but that the FDR is impossible for the turn, and all of the eyewitnesses are lying no good for nothing government operatives?

Cause if I am understanding this correctly, JFK is asserting a 330 degree turn that did happen, was impossible. Or did I miss something?



posted on Dec, 10 2009 @ 11:47 PM
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767doctor

I'll post the schematic for our DFDAU and FQIS for you. I'm only doing it as educational tool for you though. When you see how different two 757's can be in a given system of the same ATA chapter and section(ie DFDAU inputs 31-31-01 and Fuel Quantity 28-41-01), maybe some of what I've been telling you will sink in.



JFRickenK

Also my 757 manuals show port 29 NOWHERE... although the 747 manual I have does show 3 instances of port 29 being referenced in the EFIS





As promised.

DFDAU Input Ports.

Note all the port number assignments in the schematic against the 757-3B Data Frame Layout Ports. For example:

FCC L-A-4 -> Port 3
IRU L-A-3 -> Port 15
LRRA L-A-2 -> Port 20
EICAS L/R-A-1 -> Port 14
FQMS -> Port 29

If your 757 manual doesn't match, it probably has a different(older) FDAU/FDR installation and would need to be decoded with the applicable DFL. I'm guessing probably 757-1 or 757-2, which don't seem to go higher than Port 28, so fuel parameters wouldn't be polled on those aircraft.

The mystery is solved.

Back to our regularly scheduled debunking...



posted on Dec, 11 2009 @ 12:51 AM
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I did my own poking around and came up with a rated stall speed (flaps up, gear retracted) of somewhere less than 150 knots making that final turn very possible to achieve with a large margin of safety.




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