Quote:
Originally Posted by DGthe3
That assumes that the SR-71 doesn't need to refuel. It needs to refuel every 3000 miles or so. So it would need to refuel 8 times to go around the world. I don't know how quick that can happen, but it would add a couple hours to the time for sure.
Also, when I found the range from wiki I read this little tidbit: "The SR-71's Pratt & Whitney J58 engines never exceeded test bench values above Mach 3.6 in unclassified tests." They didn't exceed 3.6 in unclassified tests. Wonder what they got them up to in the classified ones . . .
Also, the stealthyness was compromised by its exhaust which had its own radar signature. Can't win 'em all. |
All excellent points DG. I forgot about the range issue. Gotta burn a ton of fuel to haul that much ass. About 8000 gal/hr at cruise in fact.
Those test bench values...I'm not sure how to take those. I'm guessing they took the effective exhaust velocity value and thats the 3.6M they are quoting. In an ideal ramjet engine, in laymans terms, the speed the air goes in is the same speed that its coming out, so that IS how fast you are going. All you are doing is dumping fuel into the ramjet to ignite it and keep yourself going. However the J58 is a ramjet/turbojet hybrid (I think I said turbofan before which is WAY off, my bad, stupid mistake I know) so actual speed will vary a lot from an ideal ramjet and with also vary some from bench values at ideal conditions.
When they tested those engines, they had to leave the hangar doors open to let more air in. It was so powerful that it started slowly sucking things like tool chests full of tools towards the intake.
Hahaha, I like the exhaust comment. Yeah, those contrails were kind of unavoidable. 50+ inch diameter columns of boiling air coming out of those engines are pretty hard to hide.