3 ms·

> So that’s a minimum of 4 airliner sized support aircraft, including all of their parts, fuel use, and crew, flying out of a minimum of 2 different bases just

> So that’s a minimum of 4 airliner sized support aircraft, including all of their parts, fuel use, and crew, flying out of a minimum of 2 different bases just to make a single SR-71 operational mission happen. Why can't it be 2 support aircraft? Is the SR-71 mission too long for the tanker to stay in the air? The tankers can also service other aircraft so they aren't necessarily put in the air exclusively for the SR-71. It's still an expensive plane though.

qbrass 3y ago
The SR-71 won't be anywhere near the first tanker when it needs fuel again. The fuel itself isn't common to most aircraft, which means the tanker has to carry fuel specifically for it so it.
- bradknowles 3y ago
  Correct. The SR-71 uses JP-7 fuel, and is the only aircraft in the fleet known to do so. So, the USAF has to have custom KC-135Q tankers just for SR-71s. They can't be used for any other fuel. The thing that made it obvious to me that there was a replacement for the SR-71 was that when they retired the aircraft, they didn't retire any of the tankers. That meant there was now some other unknown aircraft flying that also used JP-7, and it must therefore be the replacement for the SR-71. Note that JP-7 is so hard to light on fire that if you throw a match into a bucket filled with JP-7, the match will get snuffed out. You've got to be a lot hotter than a match to light that stuff.
  - satiric 3y ago
    Your anecdote about JP7 being hard to light in fire is also true for pump gas. The liquid gas is not flammable, only the aerosolized gas is.
    - bradknowles 3y ago
      But if you did the same experiment with 87-93 octane gasoline, you would set the fumes on fire as the match went into the bucket. And those fumes would continue to burn. The same is not true of JP-7.
z303 3y ago
The SR-71 used a different high flashpoint fuel (JP-7) to most aircraft, which require separate tankers (KC-135Q) with segregated storage.
- Phrenzy 3y ago
  No. The Q's ran on JP-7. They had the turbojet engines, while most other tankers had turbofans.
  - z303 3y ago
    The Q like most early KC-135 used used Turbojets(J57) later upgraded to Turbofans (CFM56) as the T J57: https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57 https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57 CFM56: https://en.wikipedia.org/wiki/CFM_International_CFM56 https://en.wikipedia.org/wiki/CFM_International_CFM56 As far as I know only the A-12 family and the X-51 used JP-7 given it needed Triethylborane (TEB) to ignite. https://en.wikipedia.org/wiki/JP-7 https://en.wikipedia.org/wiki/JP-7 https://en.wikipedia.org/wiki/Triethylborane https://en.wikipedia.org/wiki/Triethylborane More on the KC-135Q/T https://www.blackbirds.net/tankers/kc135q.html https://www.blackbirds.net/tankers/kc135q.html http://www.habu.org/kc-135q/kc135q.html http://www.habu.org/kc-135q/kc135q.html
Phrenzy 3y ago
When they were still flying, I worked on them at Beale AFB. You always knew when an SR was going to take off. About an hour prior, 2 KC-135Q's would take off like a bat out of hell. They would always use water injection and you could see their black smoke trails. An hour later, you would hear a giant rumbling coming from the flight line. It would get louder and louder until it was all you could hear. As the SR shot off into the distance, you could slowly make out the din of all the car alarms on base. They would sometimes need 4 tankers and they would shoot off in pairs. I was told they always had two tankers per fill up. They would grab some from one and then some more from the other. Back in the 90's it was estimated that each SR flight had a cost of at least a million dollars with fuel costs, wages, etc.

qbrass 3y ago

The SR-71 won't be anywhere near the first tanker when it needs fuel again. The fuel itself isn't common to most aircraft, which means the tanker has to carry fuel specifically for it so it.

bradknowles 3y ago
Correct. The SR-71 uses JP-7 fuel, and is the only aircraft in the fleet known to do so. So, the USAF has to have custom KC-135Q tankers just for SR-71s. They can't be used for any other fuel. The thing that made it obvious to me that there was a replacement for the SR-71 was that when they retired the aircraft, they didn't retire any of the tankers. That meant there was now some other unknown aircraft flying that also used JP-7, and it must therefore be the replacement for the SR-71. Note that JP-7 is so hard to light on fire that if you throw a match into a bucket filled with JP-7, the match will get snuffed out. You've got to be a lot hotter than a match to light that stuff.
- satiric 3y ago
  Your anecdote about JP7 being hard to light in fire is also true for pump gas. The liquid gas is not flammable, only the aerosolized gas is.
  - bradknowles 3y ago
    But if you did the same experiment with 87-93 octane gasoline, you would set the fumes on fire as the match went into the bucket. And those fumes would continue to burn. The same is not true of JP-7.

z303 3y ago

The SR-71 used a different high flashpoint fuel (JP-7) to most aircraft, which require separate tankers (KC-135Q) with segregated storage.

Phrenzy 3y ago
No. The Q's ran on JP-7. They had the turbojet engines, while most other tankers had turbofans.
- z303 3y ago
  The Q like most early KC-135 used used Turbojets(J57) later upgraded to Turbofans (CFM56) as the T J57: https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57 https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57 CFM56: https://en.wikipedia.org/wiki/CFM_International_CFM56 https://en.wikipedia.org/wiki/CFM_International_CFM56 As far as I know only the A-12 family and the X-51 used JP-7 given it needed Triethylborane (TEB) to ignite. https://en.wikipedia.org/wiki/JP-7 https://en.wikipedia.org/wiki/JP-7 https://en.wikipedia.org/wiki/Triethylborane https://en.wikipedia.org/wiki/Triethylborane More on the KC-135Q/T https://www.blackbirds.net/tankers/kc135q.html https://www.blackbirds.net/tankers/kc135q.html http://www.habu.org/kc-135q/kc135q.html http://www.habu.org/kc-135q/kc135q.html

Phrenzy 3y ago

When they were still flying, I worked on them at Beale AFB. You always knew when an SR was going to take off. About an hour prior, 2 KC-135Q's would take off like a bat out of hell. They would always use water injection and you could see their black smoke trails. An hour later, you would hear a giant rumbling coming from the flight line. It would get louder and louder until it was all you could hear. As the SR shot off into the distance, you could slowly make out the din of all the car alarms on base. They would sometimes need 4 tankers and they would shoot off in pairs. I was told they always had two tankers per fill up. They would grab some from one and then some more from the other. Back in the 90's it was estimated that each SR flight had a cost of at least a million dollars with fuel costs, wages, etc.