The SR71

On a tour of the Blackbird I learned some astounding facts. The Blackbird, of which one model is the SR71, gets hot when flying at

2100 MPH. But how hot is really mind boggling. Especially when the age of this aircraft is considered. The first one flew in 1961, I believe. The skin around the cockpit heats to 600 degrees F! But that's nothing. The leading edges went up to 1100. And behind the engines the skin was over 3000!!! The planes would take off with 1/2 full tanks. Once airborne they would fill up from air tankers which had been aloft for quite a while at fairly high altitude to cool the fuel down. This fuel was pumped around inside the plane to cool the fuselage. You can imagine how the pilot would have cooked with the skin around him at 600 degrees. After the fuel did it's cooling job it was used in the hydraulics as the working fluid. By this time it was ready for the engines and was burned. The plane did leak fuel when on the ground. When the skin got hot the leaks were sealed. This seems to me that the outer skin must have also been the tank wall. The tanks were pressurised with nitrogen as the fuel was drawn out to prevent collapse when the plane was at lower altitude. This seems to me that what was really being prevented was the collapse of the plane itself! A truly amazing piece of engineering and still, after 45 years, the fastest plane ever built. ERS
Reply to
Eric R Snow
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Yes, it is (was) an amazing piece of engineering, but I really doubt it's still the fastest.

Reply to
Dave Lyon

Reply to
David Billington

"Eric R Snow" wrote in message news: snipped-for-privacy@4ax.com... | On a tour of the Blackbird I learned some astounding facts. The | Blackbird, of which one model is the SR71, gets hot when flying at | 2100 MPH. But how hot is really mind boggling. Especially when the age | of this aircraft is considered. The first one flew in 1961, I believe. | The skin around the cockpit heats to 600 degrees F! But that's | nothing. The leading edges went up to 1100. And behind the engines the | skin was over 3000!!!

Ah, you missed a few cool facts about another job of the fuel. For takeoff, standard JP is used, and once it reaches some point, it's refueled with a really thick fuel, something like grease or jelly, I don't recall. This fuel is circulated through the leading edges and prevents that part from overheating and thins it enough for burning in the engine. Once it gets to cruising altitude, it's refuel again and this time with an even thicker fuel, performing the same purpose. The speed of the SR-71 was only to avoid missiles that would have been able to reach it at altitudes it loitered. For those record runs across the states, I doubt it reached altitude or refueled, since I think a full tank of regular JP was all it needed for that run.

It's been awhile since I learned this, and obviously forgot a lot, so anyone feel free to correct me.

Reply to
carl mciver

I know that temp seems way too high. But I think that they must have used the same nickel alloys that were in the engine. It looks like the engine sort of just turns into the wing at the rear. So there certainly could have been the same high temp alloys made into skin in that relatively small area. By the way, the engine gets 6 inches longer when up to temp. And 2 1/2 inches wider. They didn't say how much longer the plane grew. ERS

Reply to
Eric R Snow

Well, it's the fastest JET plane. The X-15 was a rocket plane and traveled well over 4000 MPH. Tha's nothing though. The fastest land speed recorded is over 6000 MPH. To achieve this the rocket is attatched to a sled which rides on tracks which are surrounded by a thin plastic tube filled with helium. The tube is destroyed as the sled passes.Of course, these are not piloted. ERS

Reply to
Eric R Snow

... The Discovery channel had a show or two on the SR71. They said that the fuel was created specifically for it and it cost $8 a QUART! I read that when the SR71 was taken out of active service, cost was a big part of the decision. That it cost $million per flight! At $8 a quart, the fuel must have been a part part of that cost.

Yeah, me too. I've probably got it all wrong 8-)

Bob

Reply to
Bob Engelhardt

Reply to
Bradford Chaucer

There is a for real, free online SR-71 flight manual up on this site.

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Just click on the 'SR-71 Flight Manual' link... note they will try to sell you a printed copy first, but if you scroll down a little, you can read it all free right from the site. Lots of interesting stuff, over a thousand pages they say, IIRC.

Reply to
Erik

Cooled by the fuel to keep it below melting temp.

Richard

Reply to
Richard Lamb

How about the 'Aurora'?

Best regards, Spehro Pefhany

Reply to
Spehro Pefhany

What flying gas station can get to SR-71 cruising altitude to refuel it??

Nor was the fuel used in the hydraulics system. They developed a special hydraulics fluid for use in the SR-71.

Nor have I ever read of them using standard JP or standard military JP for takeoff. Everthing I have ever read it was always loaded with the special fuel (JP-5) IIRC.

Hugh

carl mciver wrote:

Reply to
Hugh Prescott

I know this is getting pretty far off topic, but I've been wondering about this for a while. The SR-71 has been retired for a few years now. As far as I can gather it may be expensive, but it is still basically invulnerable. SOMETHING has to have taken it's place, right? Why give up such a valuable tool if we don't already have something better? There's really only so much you can do to improve resolution of orbiting cameras, so I'm thinking we've got some unmanned drones that are more advanced than what we've seen in Iraq... Obviously anyone who knows the answer to this isn't going to be posting it here, but I'm curious to hear other thoughts...

Maybe it's the other way around. Maybe it's the new generation of $500, hypersonic, Taiwanese surface to air missiles we haven't heard about yet... :)

Reply to
Larry Fishel

Mostly it was replaced in function by sattelites

Reply to
Brent Philion

Satellites have their place. My problem with them is that position and orbit data is most easy to come by, allowing leisurely cover up's and work arounds. Also, if one isn't positioned correctly, it might take hours or even days to get a good look at something.

The SR-71, and even stealthy drones can sneak up on most anyone, pretty much anywhere, anytime.

One advantage of drones is most can easily 'sucker punch' juicy targets of opportunity in real time, if one should arise. The ability to loiter for long periods is another big plus.

Erik

Reply to
Erik

Hugh Prescott wrote in news:43d9a9d2_2 @newsfeed.slurp.net:

The fuel used by the Blackbird was designated "JP-7" and is unique to that aircraft.

Reply to
Eregon

UAVs. Relatively cheap and expendable. No crew to show up on TV in Pipelinistan to embarrass us. loiter time measured in days and flyable from the facilities on US soil by guys and girls that can work in shifts and go home for dinner each day. Steathly so as to be very hard to shoot down, even if the Bad Guys know they are up there, somewhere.

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Reply to
Al Dykes

Well, it's the fastest JET plane. The X-15 was a rocket plane and traveled well over 4000 MPH. Tha's nothing though. The fastest land speed recorded is over 6000 MPH. To achieve this the rocket is attatched to a sled which rides on tracks which are surrounded by a thin plastic tube filled with helium. The tube is destroyed as the sled passes.Of course, these are not piloted. ERS ====================================== I take it, you're probably speaking of the Test Sleds, and High Speed Test Track they have out at Holloman AFB in New Mexico? Mark

Reply to
Mark D

Hugh, I can't say for sure because I never flew the thing. But the tour guide was very specific about the use of the fuel (JP7 I think) as the hydraulic fluid. He stressed this. Because it was so far from the usual. However, the plane we saw was built before the SR71. It carried a drone. Maybe they changed the system after this earlier model was built. ERS

Reply to
Eric R Snow

I don't buy that. Satellites are in a fixed orbit. Often, surveillance needs to be in a different spot, or at a different time than what satellites can provide. I'm with Brian. The military doesn't declassify something unless it's so outdated that it serves no useful military purpose. We obviously have filled that need with something more sophisticated.

Reply to
Dave Lyon

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