Mighty Moon Engines Pt. 1
The development of the Saturn V rocket entailed incredible challenges, but perhaps none so daunting as the creation of the F1 rocket engine, the first-stage powerplant for the mighty booster. Approved for development in the 1950's by the US Army (because, if for no other reason, the Soviets were developing big rockets), the F1 project migrated to NASA when the agency was created. The contract went to Rocketdyne in Canoga Park, California, a division of North American Aviation. This was a huge leap in rocket engine design, and while some of the notions involved were in effect a scaling-up of existing designs, much of the work was well beyond anyone's experience. At this time, large rocket engines were producing on the order of 100,000 or (later) 200,000 pounds of thrust... the F1 would create 1,500,000 pounds! And while cryogenic engines were the trend of the future (supercool mixtures of liquid hydrogen and liquid oxygen), the F1 would produce this power from a mix of liquid oxygen and plain old kerosene.
But early on, the project exhibited growing pains. One major area of concern was combustion instability. When a combustion chamber is scaled up to these dimensions, and the mixed fuels are ignited inside, acoustic waves begin slamming around the chamber and can cause big problems. And in those days, before CAD programs and when computers, such as they were, used that modern innovation- the punch card- engine designs were tested by building and firing. As often as not, they exploded, and the fragments were gathered for a failure analysis. The F1 exploded a lot. And the reason, in most cases, was the gremlin of combustion instability. But the Rocketdyne engineers had a solution in mind, straight out of their collective WWII experience with that simplest of argument solvers, high explosives...
[TO BE CONTINUED]