I was incredibly fortunate to have enjoyed Allan Acosta as a teacher, a friend, and as a mentor. When I was a young post-doc back in 1969, I was lucky enough to be assigned an office in the von Karman building next to an office occupied by Allan. From the start our interests and personalities drew us naturally together and so began 50 years of friendship and the most fruitful collaboration of my time. I recognized early that Allan was a truly remarkable engineer, one of those rare individuals as talented in synthesizing machines and experiments as he was in analyzing phenomena. I remember vividly the first time we flew back to Huntsville, Alabama in the 1970s to talk to NASA about a possible research program. The aura of von Braun and the Peenemunde kids still hung heavy around the Marshall Space Flight Center and the Redstone Arsenal and the huge test facilities gave the place a futuristic dimension. The Space Shuttle was then just a paper idea and the planned power density of the main engines were scary with all kinds of possible consequences.
That visit was the beginning of a long and very productive period in Allan’s career as well as my own – the beginning of a long sponsorship by NASA and a marvelous collaboration between Allan and I. Together we created a number of remarkable experimental facilities – facilities that in later years spawned copies in many institutions around the world – from Osaka, Japan, to Pisa, Italy, and many other places. But none that equaled the originality and productivity of our “pump lab” in terms of the quality of data, new information and new concepts. That data and information are now used worldwide throughout the rocket and pump design industries.
Several generations of graduate students as well as numerous undergraduates contributed to and were witness to those events. Allan was an inspirational teacher and along with all those students I learnt from him both the art and science of teaching. He made a fundamental contribution to whatever later success I enjoyed in the classroom. At the end of my teaching career, the students in my fluid mechanics class videotaped my lectures and, when I look at those tapes, I see Allan’s technique and even his gestures unwittingly reproduced.
But we also had great fun away from campus for we were both adventurers at heart. Allan taught me how to endure being hoisted to the top of a mast on a sailing boat in the middle of a gale and how to disentangle the jib hoist prior to the start of a sailing race. How to swim/snorkle under the same boat to clean off the barnacles that allegedly were preventing us winning the race. How to dive down to the bottom of a kelp bed to pry abalone off the rocks with a tire iron and then to tenderize the meat with a piece of driftwood. And many more invaluable skills.
May the force be with you, my friend.
Christopher Earls Brennen, July 2019.