On July 4th, 2014, I photographed A-12 #06938, on display at the USS Alabama Museum in Mobile, Alabama. Even though I’ve photographed #06938 numerous times, I always attempt to create fresh, interesting photos. This time, I photographed the two the liquid nitrogen tanks in the nose gear bay, shown in the final photo. The liquid nitrogen was stored in these tanks, converted into gaseous nitrogen, and used to inert the atmosphere in the aircraft’s fuel tanks. This inert nitrogen atmosphere was required, because the fuel heated 350° Fahrenheit inside the tank during flight. At that temperature, an ambient air environment could have caused combustion inside the fuel tank. If the nitrogen environment could not be achieved during flight, there was a danger of combustion inside the fuel tank.

     The Blackbird aircraft has what we call “wet wings”, which means that the skin panels of the wings and fuselage double as a fuel tank. There is no bladder inside the aircraft to hold the fuel, and every joint and screw has to be sealed from the inside, to prevent fuel leakage. When the aircraft flew at full speed, Mach 3.2, the compression of the air against the surface of the aircraft would cause serious heating, up to 620° Fahrenheit in some places. This heating would cause the entire length of the aircraft to grow about five inches in flight.

     When the aircraft would constantly contract and expand, it would cause the sealant in the fuel tanks to wear out, and fuel leaks would take place. These leaks were monitored by maintenance crews, measuring them in drips per minute (DPM). If the DPM reached its tolerance in a certain area, maintenance crews would go inside the fuel tanks, and reseal the area, which was a nightmarish process.

     Nearly every time I photograph a Blackbird in a museum, I hear a museum guest mistakenly saying, “The Blackbird had to refuel mid-air immediately after takeoff, because it leaked so badly.” This is not true. The real reason they refueled after takeoff was, when the Blackbird was fueled on the ground, the atmosphere inside the tank was ambient air. This had to be replaced with gaseous nitrogen before they reached full speed. When the tanker aircraft topped off the Blackbird’s tanks, all of the ambient air would be expelled from the tanks through relief valves. Then, as the aircraft consumed fuel, the space created in the fuel tanks would be replaced with gaseous nitrogen. This created a safe, inert atmosphere in the fuel tanks. If the aircraft, for some reason, could not create this 100% nitrogen atmosphere, the flight could not exceed 2.6 Mach. 

     It was possible to fully fuel, then defuel the aircraft to a partial load on the ground, before flight, to create this inert nitrogen tank environment, but this was a maintenance nightmare. This procedure was called a “maintenance yo-yo.” When you put the gaseous nitrogen head pressure in the fuel tanks on the ground, it caused excessive leaking, so maintenance always preferred to perform this procedure in the air, after takeoff.


Fundamental Studies in Droplet Combustion and FLame EXtinguishment in Microgravity (FLEX-2)

The Flame Extinguishment - 2 (FLEX-2) experiment is the second experiment to fly on the ISS which uses small droplets of fuel to study the special spherical characteristics of burning fuel droplets in space. The FLEX-2 experiment studies how quickly fuel burns, the conditions required for soot to form, and how mixtures of fuels evaporate before burning. Understanding how fuels burn in microgravity could improve the efficiency of fuel mixtures used for interplanetary missions by reducing cost and weight. It could also lead to improved safety measures for manned spacecraft.

  • More information: here

Credit: Reid Wiseman/NASA

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► Apollo 4 was the first unmanned test of the Saturn V launch vehicle for Project Apollo. It was an “all up” test, all three stages S-IC, S-II, and S-IVB, were tested in the same flight. The mission was also known as SA-501, Apollo-Saturn 501, or AS-501. The J-2 engine of the S-IVB 3rd stage was shut down after the stage entered orbit, then restarted in flight to simulate trans-lunar injection. A Block I Command and Service Module (CSM) was carried, and the Command Module was accelerated to high speed to simulate re-entry from a lunar mission, and recovered.

NASA’s Apollo 4 Mission, Saturn V Test: Part 2 (1968)

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I had a dream about going on our first date and this is how it went

well it certainly was an accurate reaction

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     The Space Shuttle External Tank (ET) is a three-part system, including a liquid oxygen tank (LOX), liquid hydrogen (LH2) tank and an intertank which joins the two tanks. The component shown in these photos is the LOX tank. This tank sits at the top of the complete ET arrangement. The LOX tank is much smaller than the LH2 tank, which takes up most of the main body of the ET.

     The particular LOX tank shown in this photoset is the Ground Vibration Test Article (GVTA). The GVTA was manufactured at Michoud Assembly Facility in New Orleans, Louisiana, where it is stored today. Project Habu was honored to take a behind the scenes tour of the Michoud facility on June, 18, 2014. This tank was tested at Marshall Space Flight Center in Huntsville, Alabama, and was part of a series of early test articles that were never meant to fly, but proved the integrity of the ET system.

     The final photo in the set shows a LH2 tank aft dome. Both this dome, and the GVTA show residual foam left over from their construction decades ago.


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