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Jun 27, 2013, 04:31 PM
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Merlin 1D notes





The turbopump is made by Barber-Nichols, not SpaceX. Barber-Nichols acquired the tooling in 1996 with NASA funding. They made 2 turbopumps for NASA before building the Merlin turbopumps. The NASA engines made 60,000lb thrust. The Merlin turbopump has undergone several enhancements.

The Merlin 1A spun at 20,000rpm & the engine made 77,000lb thrust. The 1B spun at 22,000 rpm & the engine made 85,000lb thrust. The 1C made 94,000lb thrust. The 1D made 147,000lb thrust. Changes in the turbopump to achieve those massive improvements were not released.

They could have used the same tooling up to 94,000lb thrust, then received a massive investment to make 147,000lb thrust possible.

Despite successful testing as individual engines, the 1st tests of all 9 engines of the Falcon 9 together in June met problems with numerous temperature sensors getting too hot. There is thermal amplification from running that many engines next to each other on a test stand, in addition to accoustic stress. Modeling thermal effects remanes a great challenge.

An amazing amount of designing goes into managing standing waves & vibration in rocket engine plumbing. The fluid lines act like musical instruments. The contained explosion creates not a constant force but an oscillating force in the plumbing, which interacts with the pressures induced by the turbopumps & creates standing waves. Not simulating the acoustic effects can cause cavitation & breakage.

Lengths of pipe have to be adjusted based on acoustic wavelength. Pipe has to be bent based on sound propagation & corrugated when flexing is required. Every change must be simulated to test for acoustic effects.





Rocket engine turbopumps are amazingly hard to manufacture. Unfortunately, they still can't be 3D printed. The space shuttle impellers needed 12 hours of machining to achieve the required precision. It would be surprising if the Merlin 1D turbopumps were actually made in Colorado.
Last edited by Jack Crossfire; Jun 27, 2013 at 04:53 PM.
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Jun 27, 2013, 08:14 PM
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Hmm... I thought I heard the pumps were the next item to be manufactured in house. There was a link somewhere in a forum in spaceflight.com

I know they are on their way to being 100% in house.


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