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Post by JayUtah on Sept 26, 2005 23:36:10 GMT -4
LOL, pretty predictable. I've seen nothing from Costella and Fetzer except hiding behind their academics, probably to hide the likelihood that neither of them has ever investigated a crash before nor been within ten miles of where airplanes are actually designed and built. My background happens to be in mechanical engineering and computer science, the latter being extremely pertinent to the digital fly-by-wire engineering in his examples. In any case I have given my specific statements. If Costella is just going to wave his diplomas and ignore the counterclaims, then it's clear what little good all those degrees do. Remember, this is the guy who -- on the basis of those same credentials -- pronounced my photographs "impossible". If he wants to talk facts then I'm available. If he's just going to play I.Q. bully without any real discussion, then he's welcome to keep teaching high school while I build the next generation of airliners (and, if I'm lucky, moon-capable spaceships).
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Post by JayUtah on Sept 26, 2005 23:55:33 GMT -4
I am impressed with all of the discussion so far on this thread, but I need to point out that some of it is getting off topic as a result of not knowing exactly what Fetzer, et al, have claimed.
I feared this. Although I said I was speaking only generally, I said this only once. And since then I have been probably a bit too specific. As I said, my interest in Wellstone's case is only casual, although my interest in aerospace design is considerable.
The switches, governors or actuators (whatever they call them,) are responsible for setting the pitch of the propellers.
Ah, that puts some of the other quotes in context. I think I was misled by claims of audibly faltering engines and references to "overspeed". In a turboprop the rotation of the engine can be controlled in part by the propeller blade pitch. Increasing the propeller angle of attack produces more drag on the propeller and slows it down.
The propeller also adds overspeed constraints. Over-rotating the prop can cause it to throw a blade, a catastrophe from which no airplane of that size would be expected to recover. But again, there are frequently purely hydromechanical control systems to mitigate and back up any purely electrical system that might be installed. And again, studying the actual design would be required in order to give a fully authoritative answer.
Switches, governors, and actuators are all different things, as I'm sure you know. As an engineer I can't afford to hand-wave when I conduct failure investigations. I have to know exactly how the various components are expected to interact, and exactly what mechanism led from initiation event to the final failure. Postulating some sort of magic ray gun that affects the prop pitch adversely from a distance is not science, no matter what letters appear after the proponents' names.
My credentials are in analysis in general, and specifically in electronic signals and intelligence analysis of weapons systems radars.
Impressive expertise to have. Well done.
...they [Fetzer and Costella] most often misinterpret what they read...
That is unfortunately to be expected even from well-educated, sincere people who simply lack the appropriate domain knowledge.
I caution all of you against basing YOUR arguments on what you THINK he is implying.
A well-considered and important warning. When speaking in general, responding to excerpts and quotes, red-herring arguments are likely unavoidable, the worst case being a completely straw man.
One question for JayUtah: Are you the James M that is a member of the Education Forum?
No, sorry.
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Post by craiglamson on Sept 27, 2005 0:00:24 GMT -4
Yes it is.. And remember that Fetzer has declared that Costella is also an expert on the properties of light...LOL! John Costella, Ph.D., a physicist with specialization in light and the properties of moving objects. www.spartacus.schoolnet.co.uk/JFKfetzer.htmJohn Costella, PhD, is a physicist and engineer with a background in optics, the properties of light, and the mechanics of moving objects. He has recently begun to apply his expertise to the analysis of the film with significant results. For additional information, go to www.ph.unimelb.edu.au/~jpc. www.d.umn.edu/~pnuhring/JFKSymposium.html#Presenters
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lenbrazil
Saturn
Now there's a man with an open mind - you can feel the breeze from here!
Posts: 1,045
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Post by lenbrazil on Sept 27, 2005 0:26:06 GMT -4
I missed thay Jay fill me in, do you have a link?
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golfhobo
Venus
DAMN! That woulda gone in the hole IF....
Posts: 86
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Post by golfhobo on Sept 27, 2005 0:44:56 GMT -4
How about this line from Fetzer. Is there any truth to it? "the NTSB said they lost track of their airspeed, that cannot occur without a commensurate loss in altitude" This doesn't make sense to me so if they speed up they automatically gain altitude? Len No, Len, not true. Altitude can be maintained through input and changes in pitch control as was done during the simulations. As you reduce airspeed, you must pitch the nose down just a bit to maintain, or indeed increase, lift over the wings and thereby your altitude. If you couldn't reduce airspeed without losing altitude, you'd have to time everything perfectly (including head or tailwinds) in order to reach the runway threshold before crashing into the terrain. Speeding up does not increase altitude unless you likewise change the pitch.
As usual, Fetzer is blowing smoke, the color of which he has no friggin idea. There is much more to flying a plane than just acceleration and angle of attack. The best analogy I could give is that the two dimensional angles of glide path and acceleration are affected by a THIRD dimension and that is the physical orientation of the plane and its associated 'control surfaces' in space (and plane.)
In fact, the plane was probably maintaining altitude fine until the airspeed bled off to the point that the airflow over the wings was "spoiled" because they DIDN'T make the control adjustments necessary, at which moment - immediately and without warning - the plane stalled.
Now, don't go quoting me until Obviousman has had a chance to "polish me" the way Rees did.
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golfhobo
Venus
DAMN! That woulda gone in the hole IF....
Posts: 86
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Post by golfhobo on Sept 27, 2005 0:58:20 GMT -4
RE: ...they [Fetzer and Costella] most often misinterpret what they read...
"That is unfortunately to be expected even from well-educated, sincere people who simply lack the appropriate domain knowledge."
It's actually worse than that. Not only do they lack domain knowledge, they just seem to lack English comprehension skills. Did you take a look at that scientific notation I asked about? The translation of the number itself is not really important. It equates to Costella's initial claim (which I believe was correct) of a catastrophic crash once in 500,000. The problem was in the way they then "extrapolated" that and the part about larger probabilities into a claim of a crash every 33 flights. It's clear to me that the author was intending to say that the probabilities of a crash became less with newer shielded avionics (like the Wellstone plane was retrofitted with) and was likewise less with older planes that would not be affected simply because they didn't HAVE them.
With no prior knowledge of this Costella fella, I immediately lost all respect for his credentials AND his analytical skills.
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Post by craiglamson on Sept 27, 2005 1:00:15 GMT -4
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Post by JayUtah on Sept 27, 2005 1:08:59 GMT -4
www.clavius.org/a11rear.htmlSpecifically figures 4 and 5. I don't remember exactly what his comment was, but I do remember he said they were somehow physically impossible. What kind of a scientist ignores empirical evidence and relies instead on abstract theory? Education is a good thing, but if all one ever does is sit in a university office and pontificate, then one very quickly loses touch with the real world. I wonder how well Fetzer would fare at my job, where there's no such thing as tenure and with dozens of eager youngsters nipping at his heels.
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Post by craiglamson on Sept 27, 2005 1:34:18 GMT -4
To paraphrase Costella he said he would not trust any photographs to prove this ponit, since they are just too easy to manipulate. He requested detailed maths to prove it was possible, and he even said he had his students try to replicate the experiment and failed. How I don't know. He was given detailed instructions on how to take a similar photograph but I guess its just not within his area of expertise to do so. He must not have a PhD in using a point and shoot digital camera....
It is interesting that everyone else who has tried has be able to replicate the results.
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golfhobo
Venus
DAMN! That woulda gone in the hole IF....
Posts: 86
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Post by golfhobo on Sept 27, 2005 1:38:48 GMT -4
JayUtah, your dissection of the Costella piece which this thread is based on was absolutely devastating. I wish I'd have thought of some of that.
".....Second, the F-111 was an older design aircraft, not intended to fly in the radio-rich battlefield of the late 20th century.
In fact the EMI implicated in these crashes were actually powerful, modern U.S. jamming signals specifically designed to interfere with and disrupt certain kinds of avionics. This can include simple radio interference that can spoof simple things such as radar altimeters and direction-finders. The crashes actually occurred in 1986 during the bombing of Libya ..."
I hadn't thought about the design window of these F-111's when he first made the claim. It just so happens that I was "on duty" from my satellite intercept ground station during this little "war." There was, indeed, a rare mix of anti radar technologies at play in this battle. Our most modern jamming techniques were being used against their SAM 2 radar sites to keep them from launching against the 111's, AND the Libyans had next generation MIG 25's that were the first to use Markham which is a flight and fire control system that allowed their MIGs to "take off, seek, acquire, and fire" at us without the pilot or ground controller EVER saying a word! In fact, this little slap on the wrist was delayed until we had developed effective jamming systems to counter Markham. Apparently, the F-111 design and modification teams didn't "get the memo."
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golfhobo
Venus
DAMN! That woulda gone in the hole IF....
Posts: 86
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Post by golfhobo on Sept 27, 2005 2:04:15 GMT -4
"The most disastrous times for electromagnetic interference to the control system is during takeoff and landing, when there is little room for error nor time to correct it. This is why you are told not to use cell phones, computers, or any other electronic device when an aircraft is taking off or landing."
Costella finally gets one thing right. The takeoff and landing phases are, indeed, the most dangerous moments of flight, and he admits that there is little room for error or time to correct it. It only took ONE small error to bring down the Wellstone flight, and those pilots committed MANY errors.
"Anyone who could not conceive of an aircraft being brought down by even a relatively small-sized EM emitter, therefore, ought to pause the next time they continue to use their laptop computers or cell phones when their planes are about to take off. It might turn out to be their final flight.
...This is why you are told not to use cell phones, computers, or any other electronic device when an aircraft is taking off or landing."
This claim ALMOST worked for him. Until about 2 weeks ago when CNN aired a brief news flash that said after years of study, the FAA has found that these small electronic devices have NO EFFECT WHATSOEVER on avionics during these two phases of flight.
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Al Johnston
"Cheer up!" they said, "It could be worse!" So I did, and it was.
Posts: 1,453
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Post by Al Johnston on Sept 27, 2005 3:06:43 GMT -4
There was an interesting article in New Scientist a few weeks back, suggesting that the systems that could be affected by cellphone transmissions were secondary ones like GPS navigation. Which is still potentially very dangerous: most cases of Controlled Flight Into Terrain occur because the pilots have the wrong impression of where the plane actually is.
A minor quibble from further up this thread: if airspeed reduces, surely the nose must be pitched up to increase the angle of attack of the wing and so increase lift to maintain altitude?
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Post by JayUtah on Sept 27, 2005 9:21:13 GMT -4
Apparently, the F-111 design and modification teams didn't "get the memo."
And they weren't the only ones. Some guided munitions went astray too during those missions, thought also to be the effects of friendly jamming. There was collateral damage. I was in Sicily when that attack occurred, living among people of Libyan extraction. It took a long time for the U.S. to admit that some of its weapons landed off-target, and even longer for them to admit that it was because of their own ECM.
I don't know what was the precise mechanism of disruption in the F-111 in those cases. But I believe that Costella has misrepresented the account in order to make the F-111 seem more sensitive to EMI than it really was.
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Post by JayUtah on Sept 27, 2005 9:37:42 GMT -4
...suggesting that the systems that could be affected by cellphone transmissions were secondary ones like GPS navigation.
I've heard that too, but I haven't seen any of the science. And, like all EM effects, I suppose it would vary with one's distance from the equipment. If one is seated in row 35, he is unlikey to disrupt anything in the avionics bay. If one is in the avionics bay...
...most cases of Controlled Flight Into Terrain occur because the pilots have the wrong impression of where the plane actually is.
Well, to be precise, it's because they have the wrong impression of where the terrain is. :-) The plane is under and behind the pilot at all times.
if airspeed reduces, surely the nose must be pitched up to increase the angle of attack of the wing and so increase lift to maintain altitude?
Well, it depends. You have to stay above stall speed. If your airspeed is dropping and you don't know why, you must lower the nose in order not to stall. If you reduce power by throttling down your engine(s) and wish to maintain altitude, you must raise the nose in order to achieve a higher angle of attack, always avoiding the stall of course. Lowering thrust and raising the nose (increasing drag) will lead to a significant drop in airspeed.
Most airplanes have a "sweet spot" in terms of cruise flight. That is a combination of thrust and attitude that maintains altitude with a minimum of fuel. For most airplanes that attitude is slightly nose-up.
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Al Johnston
"Cheer up!" they said, "It could be worse!" So I did, and it was.
Posts: 1,453
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Post by Al Johnston on Sept 27, 2005 10:13:25 GMT -4
Well, to be precise, it's because they have the wrong impression of where the terrain is. :-) The plane is under and behind the pilot at all times. As in the legendary Aer Lingus pilot asked for his height and position: "I'm six foot two, sitting in the front..." ;D
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