ULA Releases Photo of Blue Origin BE-4 Flight Engine #1 for Vulcan Rocket

Tory Bruno, CEO of United Launch Alliance, posted on Twitter:

OK. You guys have all asked so nicely. Here is a picture of the freshly COMPLETED BE-4 Flight Engine #1 for Vulcan’s first flight, in the stand at @blueorigin 's factory.

The powerhead of the Blue Origin BE-4 rocket engine looks very complicated. Below is a photo comparing the SpaceX Raptor 1 (left) and Raptor 2 (right) engines, which use the same liquid oxygen and methane propellants and have similar sea level thrust (Raptor 2: 230 tonnes, possible 250 tonnes in future; BE-4: 240 tonnes).

BE-4’s powerhead resembles that of Raptor 1 in complexity, while Raptor 2 has been dramatically simplified, with much less plumbing and “spaghetti” adorning it. In February 2022, Elon Musk said that the production cost of Raptor 2 was around half that of Raptor 1 due to the simplifications in design and manufacturing techniques.

The apparent difference in complexity is particularly striking since Raptor 2 uses a full-flow staged combustion power cycle, while BE-4 uses oxygen-rich staged combustion with a single preburner and turbine as opposed to the dual units employed in Raptor, with a correspondingly more complicated start sequence.

We’ll probably never know the numbers, but it would be interesting to compare the cost of BE-4 and Raptor 2.


The multiple parties involved in BE-4 mean it will be much more difficult to simplify BE-4.


On one of the Musk videos, there was a comment that much of the simplification of the “spaghetti” on Raptor-1 going to Raptor-2 was related to the elimination of a significant number of sensors, which had been necessary on Raptor-1 to provide the data used to improve its performance but could be eliminated from the now-optimized Raptor-2.

Perhaps there will be a similar dynamic with the BE-4.