HISTORIAN'S CORNER - July 2006
BY: Matt Grogan
I received several comments on my Titan II article in the Iast MARS STAR and will attempt to summarize these responses in this article. I appreciate the time spent preparing these comments and contacting me as these stories help provide some of the human side to the Titan II success story.
I received an e-mail from Keith Wanklin with additional information on solutions to the Titan 11 oxidizer seal problem that had prompted the 1963 Operation Wrap Up that I reported on in the last MARS STAR article. Keith said that Dam Tushar, John MacDonald and he had collaborated on the e-mail, and they recalled that there was a later study funded by the Air Force to find a new seal to replace the butyl rubber Gask-O-Seals that had been developed by Joe Marcus and his team after Operation Wrap Up in 1963. This study was initiated due to troublesome leaks in the airborne oxidizer systems that eventually developed and continued to be a problem after installation of the butyl rubber Gask-O-Seals in 1963. The leaks were attributed to the long-term degradation of the butyl rubber elastomer in the Gask-0-Seals caused by the Nitrogen Tetroxide oxidizer. John MacDonald was part of a Martin Marietta team that worked with the Air Force Research Lab in Ohio and TRW to develop and test a new elastomer that could withstand long-term oxidizer immersion and nitric acid attack. The team came up with an material called Kalrez. Kalrez is a Teflon based elastomer with excellent chemical resistance to acids/oxidizers and with physical properties (softness) equal to butyl. During 1975, the new Kalrez based seals were extensively tested in oxidizer against the butyl rubber Gask-0-Seals in identical test set-ups. Leaks occurred with the Gask-O-Seals similar to those in the airborne systems, but the new Kalrez seals experienced no leaks. Starting in late 1975, the airborne oxidizer butyl seals were replaced with the new Kalrez seals on all missiles whenever they were recycled for oxidizer leaks or for other reasons. (To recycle a missile meant taking the missile out of the silo, returning it to the base for repair, and then replacing it with a refurbished spare missile. ) In 1978, during the extensive Titan 11 Missile Silo Systems Upgrade Program, Kalrez seals were selected to replace all seals in the oxidizer silo and propellant loading systems and that change eliminated any further oxidizer leak problems. The Kalrez seals remained in the missile oxidizer systems until the last missile was deactivated at Little Rock Air Force Base in 1986. Today Kalrez is the accepted seal compound for long-term oxidizer and acid applications the world over. Keith's e-mail also pointed out that the earlier butyl rubber Gask-0-Seal concept was used on all Titan III and Titan IV launch vehicles, as Kalrez was deemed too costly and not necessary for a system that did not require long-term oxidizer immersion. His e-mail also had two interesting stories about a fuel vapor incineration system developed during Titan 11 deactivation and footprints on the Titan 11 tank interior walls.
I also received a phone call from Fred Jaeger who had worked in Engineering Propulsion during the time of the Operation Wrap Up. Fred remembers working long hours with Marty Koshar at the start of Operation Wrap Up to develop a process and criteria for leak testing the Titan II fuel and oxidizer tanks after they had been repaired. As Fred remembers, they zeroed in on the concept of pressurizing the TII tanks with Helium (He) after they were repaired and using a He "sniffer" to detect leaks. They found an off-the-shelf He leak detector (mass spectrometer) made by CEC and experimented with Helium (He) and Nitrogen Tetroxide (N204) to determine the He leak rate criteria that could be used to inspect the tanks after repairs were completed. Fred and Marty used glass pipettes and small quantities of He and the very toxic N204 in the Cold Row Lab to calibrate He leak rates against N204 leak rates and decide on acceptable He leak rates. The results of Fred and Marly's engineering efforts were turned over to Manufacturing and Quality Control who developed the specific procedures used for the tank inspections prior to returning the missiles to operational status. Fred remembers that a lot of high-level 'folks' were very interested in the results of their activities! He also recalls the construction and use of the Y-Lot facility, which was a separate building built near a Y in the road up the hill at Waterton, to process the tanks during Wrap Up.
Jim Greichen sent me several recollections of other important Titan II activities that occurred after the initial deployment of the missiles in 1962-1963. One was the development of the Coded Switch, which stuck in Jim's mind as a key issue during his watch. The Coded Switch development was a task from Ogden Material Center at Hill AFB to develop, manufacture and deploy a system to prevent unauthorized launch of aTitan ll. Jack Cousins was the electrical engineering lead on the development. Jack and his team developed a box that would prevent one of the Stage I prevalves from opening without a proper code being entered into the ground equipment, thus preventing engine ignition. (The prevalves allowed fuel and oxidizer to flow into the engines). SAC required that the switch permanently lock the prevalve in the closed posiiion'd a terrorist tried to disable the switch using a shaped charge or other ordnance. It that happened, the only way to return the missile to operational status was to de-fuel the missile, remove it from the silo, and replace the prevalve. In addition, the switch had to be safe from accidental or EMI activation. Jim remembers this entire development as being a significant technical challenge. When the task fell behind schedule, he received a phone call from a Hill AFB Colonel requesting that Jim set up an immediate meeting with then Denver President Larry Adams, which Jim did. At the meeting, the Colonel emphatically stated the importance of the Coded Switch to the Air Force and Larry Adams asked Jim if he needed any more resources. Jim replied that the technical problems would not be helped with additional resources and the problems were eventually solved with minimal delays. The Coded Switch system was installed on all 54 operational missiles.
Again, thanks to Keith/Dan/John, Fred and Jim for their inputs. Please keep the cards and letters (and emails) coming!