|Quoting ArniePie (Reply 4):|
If you take a good look at the picture you can clearly see where the wetspots originate from, namely the refueling point.
Besides I highly doubt the leakage would be so intense and certainly not upwards.
Not quite, most of the fuel leaking from the receptacle to the upper rotating beacon is from the receptacle, indicating it refueled from a KC
-135. But the fuel behind that on the spine is leaking out of the 715 split line (A/C station 715). The fuel spray on the wings doesn't match the spray patterns of the receptacle (fuel won't spray 15 or 20 feet to the side and not hit anything else on the way). But it certainly does leak upwards, look at the cover of the book "Sled Driver" by former SR
-71 pilot Brian Shul. And the fuel leak is alot more intense than you think: look at a picture of the bottom of one. Fuel EVERYWHERE as shown here if you look close:
And here's some words of a former SR
-71 pro-sup who was involved in the reactivation of how they made their choice of which aircraft to reactivate based on the condition of their fuel tank sealant:
"The first order of business was to perform fuel leak evaluations on the four SR
-71's, and to select the best two. This was accomplished at Site 2 at Palmdale, by completely filling all aircraft fuel tanks, pressurizing the system with Liquid Nitrogen (LN2), and allowing it to sit for about two hours. A hand full of previous SR
-71 mechanics were borrowed from the LM
U-2 operation to perform the tests. At completion, we would defuel the aircraft, and head to the next one. Fuel and LN2 was trucked in from NASA, and the first evaluation was performed on January 5th on 967. It had significant leaks in the nose wheel well, forward mission bays, forward bottom wing areas, top wing areas, with a severe leak (a real gusher folks) coming from tank 3 at the fuselage split line. We checked out 968 five days later. It showed significant leaks from the right main wheel well, the entire bottom fuselage, right upper fillet areas, drag chute compartment, mixer area, and two extremely severe gushers coming from the tank 3 splitline and the left aft wing beam areas. On January 12th, 971 was flown in from EAFB by NASA's Ed Schneider. The flight lasted about 10 minutes, afterburners were used for takeoff, with only 20,000 pounds of fuel onboard, and with the landing gear locked in the down position. On the 13th, we performed the evaluation of 962. This proved to be disastrous, with severe leaks just about everywhere. It leaked so bad, LN2 pressure would not build up, and we had to obtain more fuel from NASA to perform the leak test on 971, which was done three days later. 971 was in great shaped compared to the first three, with no gushers, and only five areas of concern. So the aircraft were ordered 971, 967, 968, and lastly 962. Of course, we still wouldn't have a feel for the repairs needed until the fuel cells could be opened and evaluated. Let's just say, 962 was parked and forgotten again. That was kind of sad, as it was my favorite aircraft, and Terry and I used to crew it together at BAFB."
|Quoting Drewfly (Reply 2):|
Thus, when the aircraft expands length-wise, the skin and tanks contract.
True, spirit wise. But the SR
doesn't have actual fuel tanks; the skin of the aircraft is what seals the fuel inwards. I don't know if Arniepie is right about the leaking being completely unintentional. I think Kelly Johnson and company were too smart to not know what would happen given the prep work to make the fuselage stretchable and along the same lines knowing the fuselage/aircraft skin would be the fuel tank.
|Quoting Drewfly (Reply 2):|
That is why the SR-71 had to be refueled right after takeoff, because it leaked so much on the ground.
No, that's just an urban myth. In actuality, the mx limits of fuel leakage per tank (6 fuel tanks IIRC) was 2 gallons per hour. Here's the real scoop, from one of the maintainers on an SR
takes off with almost dry tanks
Well not exactly empty, the SRs tanks hold 80,000 lbs. of fuel, the SR
-71 usually takes off with 45,000 lbs. of fuel on board. Not what I call almost dry! The SR
takes off with either 45,000 lbs., 55,000 lbs., or 65,000 lbs. of fuel. Almost all flights are refueled by KC
-135Q's (now "T"), there are a few exceptions though... one was called the "Rocket Ride", which were flown from Kadena AB
, Okinawa and then on to Northern Korea, on 65,000 lbs of fuel. The only SRs that launched with a full fuel load were the test flights from Palmdale, CA