Mach Number Versus Ground Speed, Cannot infer airspeed Options

[amazed!]

TTT has converted groundspeed, which is what radar reads, into a Mach number, and that is not a valid suggestion or conversion.

What the radar data shows is actually the ground speed because radar is groundbased. It can measure only the speed of the target over the ground. One cannot convert a groundspeed into an airspeed.

The indicated airspeed is controlled by air conditions and temperature, as is the speed of sound.

This post has been edited by amazed!: Nov 11 2007, 04:07 PM

[tumetuestumefais...]

TTT has converted groundspeed, which is what radar reads, into a Mach number, and that is not a valid suggestion or conversion.

What the radar data shows is actually the ground speed because radar is groundbased.  It can measure only the speed of the target over the ground.  One cannot convert a groundspeed into an airspeed.

The indicated airspeed is controlled by air conditions and temperature, as is the speed of sound.

The TAS will always be higher than the ground speed derived from the radar returns. It is a principle. The estimation of the speed from the radar returns mean, that it is the lowest possible speed the object was moving in the space. In fact it would move always faster, than the ground speed indicates, because the trajectory it travels due to the conservation of momentum issues (no object can move in thin air having a trajectory of sharp angles - the overfreight would be immense) would be always longer - than the simple connection of the radar return positions - travelled in same time. So if there some object would have a ground speed of 739.45mph and the same time would be at the height 33600ft, its TAS would be >=1.107Mach, also because the speed of sound significantly descends with the altitude - the function is known - and can be quite exactly computed - more exactly, than on 2 decimal places - and the speed computed exceeded Mach 1 on the first.

Tou argument is a bit a strawman one...to say at least... (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/blahblah1.gif)

And moreover, you are not saying the whole truth, because the radar is besides of the exact measuring of the position able also to measure the height of the object. Not so exactly as the position, but exactly enough to make the estimations for testing the hypothesis here even to the point we not only consider the ground speed, but also the angular speed in the space in cases of a steep descend or climb.

This thread also should be locked or the posts moved back to the FFG thread.

This post has been edited by tumetuestumefaisdubien: Nov 11 2007, 04:53 PM

[Factfinder Gener...]

This thread also should be locked or the posts moved back to the FFG thread.

In fairness, similarly to Tume's newly started thread that got locked and moved back, this does seem more like a response to the info presented in my Mach 1 thread than a separate topic.
(IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/dunno.gif)

Having said that my response, copied from the relevant thread, is as follows:

amazed! the wind was light and in any case, for the section of flight that Tume is discussing, I believe it was a crosswind. I think it thus true to say that there will not be a significant disparity between groundspeed and true airspeed.

It is TAS that is directly used for Mach calculations not IAS or CAS as you appear to be suggesting. As far as I know, temperature has nothing to do with the relationship between groundspeed and TAS (true airspeed) as groundspeed is a combination of TAS plus or minus wind speeds, i.e. plus for assisting tailwinds or minus for resisting headwinds.

Furthermore: with regards to Mach being a calculation dependent on the values of true airspeed relative to sound speed, I would say that, with his use of Mach calculators, Tume's calculations have approximately but reasonably accounted for the necessary value of sound's velocity through the air at that altitude.

Personally speaking, I would appreciate any further responses going to what I see as "the relevant thread" hyper-linked above (underlined text.) (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/salute.gif)

This post has been edited by Factfinder General: Nov 11 2007, 08:18 PM

[amazed!]

TTT

You don't understand the terminology you're using.

You don't understand the relationship between TAS, IAS, GS, and you fail to account for what wind might be present.

ALL the radar records is GS. Because of headwind/tailwind considerations, GS and IAS or TAS can be very different. That is the principle, and if you had a private pilot's license you should know that.

[Factfinder Gener...]

TTT

You don't understand the terminology you're using.

You don't understand the relationship between TAS, IAS, GS, and you fail to account for what wind might be present.

ALL the radar records is GS.  Because of headwind/tailwind considerations, GS and IAS or TAS can be very different.  That is the principle, and if you had a private pilot's license you should know that.

amazed, did you not read my post? I dealt with this I believe and Tume is not claiming to be a pilot so maybe (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/dunno.gif) cut him some slack here. (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/salute.gif)

P.S. I can only politely ask, but as I mentioned in my post above, I would personally appreciate further comments being directed towards what I see as the more relevant OP. It is going to get messy and confusing otherwise, no?

This post has been edited by Factfinder General: Nov 11 2007, 08:17 PM

[amazed!]

It's only words, FFG, so don't take it personally.

IAS is what the airspeed indicator shows.

CAS is basically the same thing, very finely tuned and not appreciably different than IAS.

TAS is IAS corrected for pressure and temperature.

Mach becomes a factor only in certain situations.

GS is the TAS corrected for the effect of wind on the aircraft's track over the ground.

Radar provides the latter, not the former.

My only point is that if we convert the radar data into a Mach speed it is a bit misleading. The GS could be a value greater than Mach 1, but that does not mean the aircraft is flying exactly that fast.

[Factfinder Gener...]

It's only words, FFG, so don't take it personally.

IAS is what the airspeed indicator shows.

CAS is basically the same thing, very finely tuned and not appreciably different than IAS.

TAS is IAS corrected for pressure and temperature.

Mach becomes a factor only in certain situations.

GS is the TAS corrected for the effect of wind on the aircraft's track over the ground.

Radar provides the latter, not the former.

My only point is that if we convert the radar data into a Mach speed it is a bit misleading.  The GS could be a value greater than Mach 1, but that does not mean the aircraft is flying exactly that fast.

OK, amazed!, I know all that good stuff (see my previous post) but seriously: the wind speed in PA on September 11 2001 at 9:00 AM was approximately 5 mph, and its direction was Northerly. If, being generous here, we call this a tailwind and subtract that 5mph from the Groundspeed to get the TAS of 734 mph: that still leaves us with an approximate estimate of Mach 1.098.

I respect you and your opinion immensely but honestly, amazed!, in this instance was it really worth setting up a counter thread over? You could have just made a post on the relevant thread (as I keep hoping you would do (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/rolleyes.gif) )

Never mind, what is done is done, but can we please continue this over at my place now? (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/yes1.gif) (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/thumbsup.gif)
WELCOME!

This post has been edited by Factfinder General: Nov 12 2007, 12:15 AM

[tumetuestumefais...]

TTT

You don't understand the terminology you're using.

You don't understand the relationship between TAS, IAS, GS, and you fail to account for what wind might be present.

ALL the radar records is GS.  Because of headwind/tailwind considerations, GS and IAS or TAS can be very different.  That is the principle, and if you had a private pilot's license you should know that.

1. The IAS we could rule out, we don't know the IAS of that flying object, we don't have FDR's.
2. We know the GS. And the GS is almost always lower (sometimes considerably - when the plane steeply ascends or descends) or equal to TAS - if there is not a considerable wind present(which wasn't - the wind that day was about 5mph nord, if I remember it well) - not: being "very different" - it is a considerable blurring of the concepts.
If you are writing "You don't understand the terminology you're using" and you had a private pilot's license, you should know that.

This post has been edited by tumetuestumefaisdubien: Nov 12 2007, 06:01 AM

[rob balsamo]

2. We know the GS. And the GS is almost always lower (sometimes considerably) or equal to TAS  - if there is not a considerable wind present(which wasn't - the wind that day was about 5mph nord, if I remember it well) - not: being "very different" - it is a considerable blurring of the concepts.

GS=TAS plus or minus wind correction.

Therefore, if there is no wind.. GS is equal to TAS.

Pull out your E6B... (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/wink.gif)

[tumetuestumefais...]

2. We know the GS. And the GS is almost always lower (sometimes considerably) or equal to TAS  - if there is not a considerable wind present(which wasn't - the wind that day was about 5mph nord, if I remember it well) - not: being "very different" - it is a considerable blurring of the concepts.

GS=TAS plus or minus wind correction.

Therefore, if there is no wind.. GS is equal to TAS.

Pull out your E6B... (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/wink.gif)

yes, I just corrected it in the post to make it more clear - with the note that the GS is lower than TAS in cases when the plane steeply ascends or descends, otherwise of course the GS~=TAS if there is no wind. But never GS>TAS when no wind, Correct?

This post has been edited by tumetuestumefaisdubien: Nov 12 2007, 06:10 AM

[amazed!]

We know the surface winds were whatever you want to assign--5 to 10 seems to be reasonable. Do we know the winds aloft? I doubt it, but I doubt they were significant in September.

We don't know the IAS and we don't know the air temp at the various altitudes involved, so it seems rather difficult if not impossible to work backwards from a known groundspeed from radar data, assuming that data is accurate.

As far as I'm concerned the system was spoofed, and all bets are off. Trying to find a value and pretending it is extremely meaningful is an exercise in futility, IMO

[tumetuestumefais...]

We know the surface winds were whatever you want to assign--5 to 10 seems to be reasonable.  Do we know the winds aloft?  I doubt it, but I doubt they were significant in September.

We don't know the IAS and we don't know the air temp at the various altitudes involved, so it seems rather difficult if not impossible to work backwards from a known groundspeed from radar data, assuming that data is accurate.

As far as I'm concerned the system was spoofed, and all bets are off.  Trying to find a value and pretending it is extremely meaningful is an exercise in futility, IMO

If we know the ground temperature and if we know there were no significant winds, we can quite exactly predict the temperature aloft and thus also the speed of sound.

We dont need a exact value. To find the possible range would be enough.

What about the spoofing or injecting read please my notes in the original thread.

This post has been edited by tumetuestumefaisdubien: Nov 13 2007, 07:03 AM

[amazed!]

I agree that an exact number is unnecessary, and impossible to arrive at in the first place.

If the radar data is authentic, it simply means the aircraft, if a Boeing, was operating above its limitations. Whether such speeds are possible is another matter.

[Factfinder Gener...]

If the radar data is authentic, it simply means the aircraft, if a Boeing, was operating above its limitations.

This, to put it mildly, is quite an understatement, amazed!

In light of Tume's analysis, it is reasonable to assume the object, if the data is authentic, was flying above Mach 1 speed for a portion of the flight.

This post has been edited by Factfinder General: Nov 14 2007, 01:37 AM

[tumetuestumefais...]

This, to put it mildly, is quite an understatement, amazed!

In light of Tume's analysis, it is reasonable to assume the object, if the data is authentic, was flying above Mach 1 speed for a portion of the flight.

In this I would stand much more on the side of amazed, because we don't know, if the object realy surpassed the speed of sound. Some data indicate something like, but in fact that are just isolate anomalies, nothing realy substantial. And I must say as deep and deeper I dig to the data I'm becoming more an more sceptical there could be realy found proven Mach 1 exceeded in the data. Some periods of fly above 600mph yes, but that would be probably maximum, what could be prooven realy without a serious doubt.

[Factfinder Gener...]

This, to put it mildly, is quite an understatement, amazed!

In light of Tume's analysis, it is reasonable to assume the object, if the data is authentic, was flying above Mach 1 speed for a portion of the flight.

In this I would stand much more on the side of amazed, because we don't know, if the object realy surpassed the speed of sound. Some data indicate something like, but in fact that are just isolate anomalies, nothing realy substantial. And I must say as deep and deeper I dig to the data I'm becoming more an more sceptical there could be realy found proven Mach 1 exceeded in the data. Some periods of fly above 600mph yes, but that would be probably maximum, what could be prooven realy without a serious doubt.

Huh? Did I miss something? This wouldn't be suprising seeing as I'm having to follow the discussion as it is being played out on THREE separate threads. (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/doh1.gif)

The radar data that you analysed showed above Mach speeds, no? The wind would have to have been excessive to lower the speed below Mach 1, and this was clearly not the case. The air temperature is reasonably well accounted for by the Mach calculator you used.

What is the problem, exactly? (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/dunno.gif)

My statement is regarding the NTSB collated radar data. If it is authentic it shows a flight profile that is radically inconsistent with a BOEING 767.

amazed!'s reply where he says that the Boeing was "operating above its limitations" was surely an understatement. If the data is authentic it could not have been operating.

This post has been edited by Factfinder General: Nov 14 2007, 03:10 AM

[dMz]

In retrospect, Mach number may have been a red herring (of whale-sized proportions perhaps?). One of the better technical papers that I've found so far on mach vs. altitude/temperature is located at:

http://www.tscm.com/mach-as.pdf

The relevant (IMHO) section states:

"The data on this graph can be obtained directly from the following formula for use at altitudes of 36,000 ft and below:

Speed of Sound (KTAS) = 29.06 * SQRT (518.7 - 3.57A), Where A = altitude (in K*ft, or thousand-feet)

This equation uses the standard sea level temperature of 59 deg_F and a lapse rate of -3.57 deg_F /1000 ft altitude. Temperature stabilizes at -69.7 deg_F at 36,000 ft so the speed of sound stabilizes there at 573 knots."

On Sept. 11, 2001, JFK airport was around 70 deg_F at approximately 09:00 EDT, so the speed of sound should have actually been slightly higher (due to lower air density at slightly higher temperature).

http://en.wikipedia.org/wiki/Speed_of_sound

[4nsicdoc]

2. We know the GS. And the GS is almost always lower (sometimes considerably) or equal to TAS - if there is not a considerable wind present(which wasn't - the wind that day was about 5mph nord, if I remember it well) - not: being "very different" - it is a considerable blurring of the concepts.

GS=TAS plus or minus wind correction.

Therefore, if there is no wind.. GS is equal to TAS.

Pull out your E6B... (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/wink.gif)
yes, I just corrected it in the post to make it more clear - with the note that the GS is lower than TAS in cases when the plane steeply ascends or descends, otherwise of course the GS~=TAS if there is no wind.

But never GS>TAS when no wind, Correct?

I suspect that the Shuttle at apogee has a GS of 20,000 knots with a TAS of 0. I tell my students to be careful of "never." Every time I see the word, I feel this atavistic urge to posit an absurd exception to the proposed "rule" Another small nit; people are talking about a 5 knot wind. Maybe at the surface, like they are now here at SRQ. However at 767 cruise altitude, they are 9 times that here. Often, in the winter I have seen an indicated airspeed of 210 knots, a TAS of 450 knots and a groundspeed going west to east of 600 knots at .82 Mach CAS. That would be the precurser to a big black smoking hole in the ground if Mach Number was based on Ground Speed. (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/cheers.gif)