July 24, 2013
The Glenn interns met in front of Building 49 to load up onto the buses headed for the Plum Brook Test Facilities in Sandusky. The hour-long ride was full of mirth and laughter as the interns played games and held interesting conversations. The roads grew more deserted as we got closer to Plum Brook and after entering the front gate, it was hard to tell that we were on NASA property. Forestry and shrubs went on for miles and miles on the 6400-acre facility. The first stop for our bus was the Spacecraft Propulsion Research Control Center. There were small mock-ups of engine parts in the entrance and the main attraction was the control room. The facility has been undergoing a tech overhaul since 1998 and has since replaced all the 60’s style screens and infrastructure. The first rocket to be fired in the B2 test facility was the Centaur rocket back in 1972.
The B2 rocket test facility is built 200 feet into the ground and has the 3rd largest chamber at Plum Brook. It uses liquid nitrogen cooling, high capacity vacuum pumps, and solar lamps to simulate the space environment. Typically the chamber reaches temperatures of -320 F at pressures of 10-6 torr. The rocket fires into a 2 million-gallon water chamber where the exhaust is cooled and extracted with steam pumps. The exhaust is fully combusted with natural gas such that the final product released to the atmosphere is steam.
Once the buses left B2, the interns all were shuttled to the Space Power Facility (SPF), which houses the largest test chambers at Plum Brook. The facility conducts tests for nuclear engines, fairing separation, and vibration and acoustic stresses. SPF was also used as the set for the first scene in the Avengers movie- a fact that was much lauded and made the facility all the better. The facility was absolutely daunting in size. The chamber is built out of aluminum so that radiation isn’t easily absorbed. This in turn is encased with concrete so it can support the pressure changes. In order to simulate space, the chamber pumps down 60 tons of air using cryogenic and mechanical pumps.
The vibrational and acoustic test stands reside in another part of the facility. The vibrational test stand has 16 actuators that can exert 30,000 lbs of force each. It is used to test instrumentation for rockets and simulates the intense vibrations that occur during the launch. The acoustics chamber has 36 horns lined symmetrically along one wall. All were of varying size, shape, and material and can produce sound levels of up to 163 dB. Special precautions are taken to try to maintain the acoustic energy within the chamber, including filling it with the inert gas, N2.
The test facilities were all impressive and led to plenty of dropped-jaws, ooh’s and ah’s, as well as photographs. Not to mention all the interns can now say they were on one of the sets for the movie, “The Avengers”!