4 ms·

It’s still a bit mind-blowing that they got rid of the SR-71 but kept the U-2.

by larrywright 6y ago

larrywright 6y ago
Also, these planes fly over the US Southwest pretty regularly. If you use a a site like OpenADSB.com you can see them.
khuey 6y ago
The SR-71 was crazy expensive to fly and maintain and the U-2 apparently is not.
- larrywright 6y ago
  The U-2 doesn’t fly nearly as high or as fast if I recall. But maybe we don’t need that any more.
justin66 6y ago
The reasons are straightforward enough, it's about cost: Now the 31 operational U-2s in the USAF fleet are about to undergo a $50m (£37.8m) update and acquire a new mission which could see them fly on for another 30 more years. $50 million would just get you a few flights of an SR-71 and its special fleet of dedicated tankers.
redis_mlc 6y ago
The SR-71 used a different jet fuel than normal, special engines, and likely required a lot of maintenance. The SR-71 program was cancelled because satellites were good enough, and the above maintenance plus over a dozen dedicated tanker airplanes (for the special fuel) made them a headache to operate. One of the most impressive things to me about the program was that after a certain date, all flights were done in radio silence, including multiple refuelings. A TLA told them that the radio calls were being tracked by Russian trawlers around the world.
- larrywright 6y ago
  I read the book about Lockheed’s Skunkworks recently, and it touched on this a bit. The big difference between a satellite and a spy plane like the U-2 and the SR-71 was that you can launch a spy plane on short notice and get the intel you need. Satellites aren’t nearly as agile. But things may have changed, perhaps we have enough satellites in enough places that we don’t have as big a problem as we once did.
  - redis_mlc 6y ago
    More headaches: Carrying film around, hypersonic missiles.
- beerandt 6y ago
  >The SR-71 used a different jet fuel than normal, special engines, and likely required a lot of maintenance. The bigger issue is refueling, which required an entire fleet of separate, dedicated tankers, so that fuel wasn't accidently mixed with the regular jet fuel. The special fuel was some sort of coal slurry, and would immediately do pretty bad things to normal jets. Additionally, the tankers needed special, segregated tanks that didn't to their own fuel supply. There was also a radioactive additive that could be used to reduce the radar cross section of the exhaust plume, although it's not clear if it was ever used. This supposedly would have been much more of a maintenance issue for engine wear and maintenance.
  - chipsa 6y ago
    The special fuel was specially distilled/blended oil. The problem with using it in normal jets is that it is so hard to light that you can't get the engines started without special ignition fluid. This poses the obvious problem for the tankers that you can't get their engines started without special engines, or segregated tanks.
golergka 6y ago
This website provides a detailed comparison: https://www.blackbirds.net/u2/c_bennett/bbird-08.html https://www.blackbirds.net/u2/c_bennett/bbird-08.html (Also, just gotta admire the "web 1.0" site that is still online after 23 years).
saberdancer 6y ago
I always felt US has to have a replacement that is currently secret. Lately I am wondering if it is truly the case, sure US does have some secret programs but with the mass proliferation of drones and with their spaceplane it's possible they don't need SR-71 replacement.
walrus01 6y ago
The SR-71 was apparently a maintenance and repair nightmare, the per hour fully calculated operating cost was quite ridiculous. The NRO obviously doesn't publish any useful unclassified info for radar or visual, infrared spectrum observation satellites newer than about 1965. But if I had to guess, a lot of its mission became obsolete when post-1980s era NRO satellites went into service.
- chokeartist 6y ago
  > But if I had to guess, a lot of its mission became obsolete when post-1980s era NRO satellites when into service. That is exactly what happened. Also it is a very politically charged event to blast a Satellite out of orbit (resulting shards). You can blast airplanes out of "your" airspace all day long and tell everyone to pound sand.

It’s still a bit mind-blowing that they got rid of the SR-71 but kept the U-2.

larrywright 6y ago

Also, these planes fly over the US Southwest pretty regularly. If you use a a site like OpenADSB.com you can see them.

khuey 6y ago

The SR-71 was crazy expensive to fly and maintain and the U-2 apparently is not.

larrywright 6y ago
The U-2 doesn’t fly nearly as high or as fast if I recall. But maybe we don’t need that any more.

justin66 6y ago

The reasons are straightforward enough, it's about cost: Now the 31 operational U-2s in the USAF fleet are about to undergo a $50m (£37.8m) update and acquire a new mission which could see them fly on for another 30 more years. $50 million would just get you a few flights of an SR-71 and its special fleet of dedicated tankers.

redis_mlc 6y ago

The SR-71 used a different jet fuel than normal, special engines, and likely required a lot of maintenance. The SR-71 program was cancelled because satellites were good enough, and the above maintenance plus over a dozen dedicated tanker airplanes (for the special fuel) made them a headache to operate. One of the most impressive things to me about the program was that after a certain date, all flights were done in radio silence, including multiple refuelings. A TLA told them that the radio calls were being tracked by Russian trawlers around the world.

larrywright 6y ago
I read the book about Lockheed’s Skunkworks recently, and it touched on this a bit. The big difference between a satellite and a spy plane like the U-2 and the SR-71 was that you can launch a spy plane on short notice and get the intel you need. Satellites aren’t nearly as agile. But things may have changed, perhaps we have enough satellites in enough places that we don’t have as big a problem as we once did.
- redis_mlc 6y ago
  More headaches: Carrying film around, hypersonic missiles.
beerandt 6y ago
>The SR-71 used a different jet fuel than normal, special engines, and likely required a lot of maintenance. The bigger issue is refueling, which required an entire fleet of separate, dedicated tankers, so that fuel wasn't accidently mixed with the regular jet fuel. The special fuel was some sort of coal slurry, and would immediately do pretty bad things to normal jets. Additionally, the tankers needed special, segregated tanks that didn't to their own fuel supply. There was also a radioactive additive that could be used to reduce the radar cross section of the exhaust plume, although it's not clear if it was ever used. This supposedly would have been much more of a maintenance issue for engine wear and maintenance.
- chipsa 6y ago
  The special fuel was specially distilled/blended oil. The problem with using it in normal jets is that it is so hard to light that you can't get the engines started without special ignition fluid. This poses the obvious problem for the tankers that you can't get their engines started without special engines, or segregated tanks.

golergka 6y ago

This website provides a detailed comparison: https://www.blackbirds.net/u2/c_bennett/bbird-08.html https://www.blackbirds.net/u2/c_bennett/bbird-08.html (Also, just gotta admire the "web 1.0" site that is still online after 23 years).

saberdancer 6y ago

I always felt US has to have a replacement that is currently secret. Lately I am wondering if it is truly the case, sure US does have some secret programs but with the mass proliferation of drones and with their spaceplane it's possible they don't need SR-71 replacement.

walrus01 6y ago

The SR-71 was apparently a maintenance and repair nightmare, the per hour fully calculated operating cost was quite ridiculous. The NRO obviously doesn't publish any useful unclassified info for radar or visual, infrared spectrum observation satellites newer than about 1965. But if I had to guess, a lot of its mission became obsolete when post-1980s era NRO satellites went into service.

chokeartist 6y ago
> But if I had to guess, a lot of its mission became obsolete when post-1980s era NRO satellites when into service. That is exactly what happened. Also it is a very politically charged event to blast a Satellite out of orbit (resulting shards). You can blast airplanes out of "your" airspace all day long and tell everyone to pound sand.