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Holy Moly! sr-71 top speed is Mach 14 (leaked document)

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posted on Dec, 13 2008 @ 08:37 AM
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Originally posted by SwordDancer
Already while accelerating the pilots and the entire plane would be crushed to the size of a pizza ( and i know this is an unrealistic example but it shows what i mean). They would have to get the crew out of the plane looking like mud (litteraly)

Huh? What does acceleration have to do with top speed?
Nothing, that's what.
Your conclusion is therefore based on a false premise.

The original post is based on a link to a post on another forum. That post was a steaming pile of crap from start to finish.
(forgive my non-lady-like description, been hanging around air force personnel too long I suppose).

Like ATSers RichardPrice and Canada_EH, I too find myself weary of the outlandish claims and assumptions embraced by some; weary too of those who are correected with sound logic and science and sill stubornly cling to their claims. If I have been instrumental in perpetuating some of these myths I apologize.




posted on Dec, 13 2008 @ 08:49 AM
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Originally posted by Travellar
I did once hear that one of the blackbird pilots commented that if anyone ever broke thier speed record, they'd have to go back up and take it again. That boast aside though, Mach 4-5 is a much more believeable number.

(oh, and that's an A-12 in that picture, Fighter Master, not an SR-71)


Not to mention it was "retired" quite a long time ago.
Rumor was they were working on a next generation SR-72 right after it had retired.

The question though is this.

First of all at take off they have to re-fuel as soon as it's airborne because it uses all the fuel just to take off and they have an air re-fuel'er in air waiting when it takes off.

Secondly at higher altitudes with the air being less dense could it increase the speed or would it cause it to actually slow down depending on what type of engine they used in it.

Just asking I was never privy to the actual engines they used as I didn't have a need to know. Most I ever got out of anyone was a crew chief saying it had 4 fighter jet engines but wouldn't elaborate past that assuming he was being serious.



posted on Dec, 13 2008 @ 12:06 PM
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Originally posted by Darthorious
First of all at take off they have to re-fuel as soon as it's airborne because it uses all the fuel just to take off and they have an air re-fuel'er in air waiting when it takes off.

Secondly at higher altitudes with the air being less dense could it increase the speed or would it cause it to actually slow down depending on what type of engine they used in it.

Just asking I was never privy to the actual engines they used as I didn't have a need to know. Most I ever got out of anyone was a crew chief saying it had 4 fighter jet engines but wouldn't elaborate past that assuming he was being serious.


Your first point about fuel was done because the plane leaked so badly on the ground. It leaked like a sieve when it wasn't flying, so that when it flew it could expand from heat. Once it was at speed, it expanded a few inches and locked all that off. So instead of filling it all the way up on the ground, they put enough onboard to get airborne and to a tanker. That way it didn't dump tons of fuel overboard.

The engines used were J-58s (only 2 of them though). They were the first engines to be certified for extended high speed flight, and to use continuous afterburner. The interesting thing about them is that they had to use JP-7 fuel, which has such a high flash point that it can put out fires without igniting. They had to use TEB (Triethylborane) to ignite the fuel. If you watch a video of the engine ignition, you'll see a green flame first. That's the TEB igniting the fuel.



posted on Dec, 13 2008 @ 01:02 PM
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Originally posted by Darthorious

First of all at take off they have to re-fuel as soon as it's airborne because it uses all the fuel just to take off and they have an air re-fuel'er in air waiting when it takes off.




Originally posted by Zaphod58

Your first point about fuel was done because the plane leaked so badly on the ground. It leaked like a sieve when it wasn't flying, so that when it flew it could expand from heat. Once it was at speed, it expanded a few inches and locked all that off. So instead of filling it all the way up on the ground, they put enough onboard to get airborne and to a tanker. That way it didn't dump tons of fuel overboard.


This is a common myth that even I fell foul of until recently.

The SR-71 did not have to refuel immediately afterward because of either of these reasons - it did not burn significant amounts of fuel during takeoff, and it did not leak to the point where it needed immediate refueling after takeoff and tank sealing.

This is a myth that is perpetuated by many many documentary makers.

The real reason is two fold:

1. The single engine performance of the SR-71 at low altitudes is terrible, so a heavily loaded aircraft experiencing an engine failure at takeoff would end up in a crater. So they took off with a reduced fuel load on most missions.

2. The fuel tanks are filled with inert nitrogen gas so as to remove the possibility of a fuel tank explosion while at high mach (the maximum allowed threshold for flight without the nitrogen inert system in operation is mach 2.6). The only way to ensure the inerting system worked correctly was to fill the tanks 100% and then allow the tanks to empty, allowing the nitrogen gas to naturally fill the void left. This could either be done on the ground (via a process called the 'yo yo') but it was a maintenance nightmare, or they could top the tanks off to 100% after takeoff (and thus after the engine out danger).

All from 'Flying the SR-71 Blackbird' by Col Richard Graham - Page 110.



posted on Dec, 13 2008 @ 01:14 PM
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Brian Shul has said in his books that they were at about Mach 4.3 over Libya in 1986. That's the fastest that I've ever heard of one flying. I just found what I had been looking for before.

He never says the speed, but doing a little math can help you figure it out. He says after they made the turn towards the Med, they were traveling a mile every 1.6 seconds. By my math that comes out to about Mach 4.3 or so.


In April 1986, following an attack on American soldiers in a Berlin disco, President Reagan ordered the bombing of Muammar Qaddafi's terrorist camps in Libya. My duty was to fly over Libya and take photos recording the damage our F-111's had inflicted. Qaddafi had established a 'line of death,' a territorial marking across the Gulf of Sidra, swearing to shoot down any intruder that crossed the boundary. On the morning of April 15, I rocketed past the line at 2,125 mph.

I was piloting the SR-71 spy plane, the world's fastest jet, accompanied by Maj Walter Watson, the aircraft's reconnaissance systems officer (RSO). We had crossed into Libya and were approaching our final turn over the bleak desert landscape when Walter informed me that he was receiving missile launch signals. I quickly increased our speed, calculating the time it would take for the weapons-most likely SA-2 and SA-4 surface-to-air missiles capable of Mach 5 - to reach our altitude. I estimated that we could beat the rocket-powered missiles to the turn and stayed our course, betting our lives on the plane's performance.

After several agonizingly long seconds, we made the turn and blasted toward the Mediterranean. 'You might want to pull it back,' Walter suggested. It was then that I noticed I still had the throttles full forward. The plane was flying a mile every 1.6 seconds, well above our Mach 3.2 limit. It was the fastest we would ever fly. I pulled the throttles to idle just south of Sicily, but we still overran the refueling tanker awaiting us over Gibraltar.

maggiesfarm.anotherdotcom.com...



posted on Dec, 13 2008 @ 09:59 PM
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reply to post by Zaphod58
 




My rough math was Mach 3.4 which is still pretty fast.



posted on Dec, 13 2008 @ 10:03 PM
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reply to post by _Del_
 


They were doing 3.5 when they went past Tripoli, and were going faster when they got out of the country. If you read the whole story he mentions mach numbers a little later, but never gives the actual top end mach number.



posted on Dec, 13 2008 @ 10:24 PM
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I just read the entire article.

A mile every 1.6 seconds is 2250mph.

He mentions they reached Mach 3.5 at 80,000' which is a touch over 2300mph. Then he says they went even faster (enough to be concerning) without giving any particulars.

Still way short of Mach 14, at anyrate



posted on Dec, 15 2008 @ 05:27 AM
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Originally posted by _Del_
I just read the entire article.

A mile every 1.6 seconds is 2250mph.

He mentions they reached Mach 3.5 at 80,000' which is a touch over 2300mph. Then he says they went even faster (enough to be concerning) without giving any particulars.

Still way short of Mach 14, at anyrate




The TRIPLE DISPLAY INDICATOR (TDI) shows the TRUE Mach Number and the indication Mach range is 0-3.99 and although this is the range on the gauge the MAXIMUM LIMIT OF THE DAFICS Signal to the instrument is Mach 3.5. So even if Mach 3.5 IS EXCEEDED it will not be shown on the TDI.

The TDI also displays the Pressure Alitude and Airspeed in Knots Equivanlent Air Speed, (KEAS) both computed by the DAFICS


There is also a Combination Airspeed/Mach Number meter operating Directly from the pitot-static pressure. The values shown on this display are INDICATED values as opposed to equivalent and TRUE Mach displayed on the TDI. This gauge reads in Knots Indicated Air Speed (KIAS) Not Mach numbers as some people seam to think.



posted on Dec, 20 2008 @ 03:00 PM
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]reply to post by ajsr71
 


I think I must be one of the very few people who believe that even Mach 3.5 has not been reached or exceeded.

I have been working on a web page to explain why and this is on my web site at


SR-71 BLACKBIRD PERFORMANCE



posted on Dec, 20 2008 @ 03:04 PM
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reply to post by ajsr71
 


A lot of people believe that Mach 3.5 has been exceeded because AN SR-71 PILOT talks about being faster than Mach 3.5. I think that's a pretty good reason to believe it. Or are you of the "all pilots are full of BS to make their planes and themselves look better" crowd.



posted on Dec, 20 2008 @ 06:02 PM
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reply to post by Browno
 


we had the avro arrow but deifenbaker had to be an ass



posted on Dec, 20 2008 @ 10:53 PM
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Please correct me if I am wrong , but aren't jet's speed measured by airflow through an external sensor? If this is the case then operating at 60-100k feet isn't the air thinner and actual speed measurements a little off? Not saying mach 14 is the proper measurement by ANY means , but doesn't that skew facts or have they calculated for that....and if THAT is the case the SR is actually slower than thought because not as much friction?



posted on Dec, 20 2008 @ 11:02 PM
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Airflow is airflow, regardless of altitude. Pressure doesn't affect the speed reading, but it might the altitude reading. At altitude, they could go faster because there was less air resistance. And air speed indicator doesn't read the pressure going into it, just how fast the air is flowing through it.



posted on Dec, 20 2008 @ 11:13 PM
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I'm not trying to be smart-ass or anything...but if the air is less dense at those altitudes wouldn't fewer air particles enter a probe?



posted on Dec, 20 2008 @ 11:44 PM
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It all depends on which airspeed you're talking about. Are you talking calibrated? If you're talking calibrated then yes, altitude does make a difference, but they correct for that.


Calibration Error
An airspeed sensor features a static vent to maintain its internal pressure equal to atmospheric pressure. Position and placement of the static vent with respect to the angle of attack and velocity of the aircraft determines the pressure inside the airspeed sensor and therefore the calibration error. Thus, a calibration error is specific to an aircraft's design.

An airspeed calibration table, which is usually included in the pilot operating handbook or other aircraft documentation, helps pilots convert the indicated airspeed to the calibrated airspeed.

Compressibility Error
The density of air is not constant, and the compressibility of air increases with altitude and airspeed, or when contained in a restricted volume. A pitot-static airspeed sensor contains a restricted volume of air. At high altitudes and high airspeeds, calibrated airspeed is always higher than equivalent airspeed. Equivalent airspeed can be derived by adjusting the calibrated airspeed for compressibility error.

Density Error
At high altitudes, airspeed indicators read lower than true airspeed because the air density is lower. True airspeed represents the compensation of equivalent airspeed for the density error, the difference in air density at altitude from the air density at sea level, in a standard atmosphere.

www.mathworks.com.../access/helpdesk/help/toolbox/aeroblks/f4-49514.html&www.google.com... earch?hl=en&q=airspeed+sensor+%2B+altitude&start=10&sa=N



posted on Dec, 20 2008 @ 11:46 PM
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Airspeed indicators work by measuring the difference between static pressure, captured through one or more static ports; and stagnation pressure due to "ram air", captured through a pitot tube. This difference in pressure due to ram air is called impact pressure which gives us KIAS, or Knots Indicated Air Speed. It DOES indeed decrease with altitude. For example, the SR-71 cruised at about 300 KIAS while is was truely going at over one thousand knots. Errors can be corrected.

[edit on 20/12/2008 by C0bzz]



posted on Dec, 20 2008 @ 11:47 PM
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That's what the INDICATOR said, but you correct for true airspeed. Some aircraft even have a true airspeed indicator on them, which gives your actual speed.



posted on Dec, 21 2008 @ 05:40 AM
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Originally posted by Zaphod58
And air speed indicator doesn't read the pressure going into it, just how fast the air is flowing through it.



Google pitot-static tube.


Pressure is exactly what the probe reads.



posted on Dec, 21 2008 @ 05:43 AM
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Originally posted by Zaphod58
A lot of people believe that Mach 3.5 has been exceeded because AN SR-71 PILOT talks about being faster than Mach 3.5. I think that's a pretty good reason to believe it.


I don't.


A greater reason to believe it isn't capable of Mach 3.5 is the work NASA did examining the feasibility of extending the performance envelope to around Mach 3.5...

The conclusion was that the reward was not worth the effort/cost.


edit: I'm not sure if thats completely in the public domain or not, a search might turn up something on the ntrs.




Originally posted by Zaphod58
Or are you of the "all pilots are full of BS to make their planes and themselves look better" crowd.


Firmly.

Do you not talk to pilots?


Half the conversation revolves around them, the other half around their planes!

[edit on 21/12/08 by kilcoo316]





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