Exciting progress in Boca! Hopper almost ready to hover. Based on tonight’s test, looks like 600 Hz Raptor vibration problem is fixed. pic.twitter.com/9bLWOHG0sV
— Elon Musk (@elonmusk) July 7, 2019
Great video. Couple notes: Raptor designed for subcooled CH4/O2, so propellant density & thrust increase up to ~8%, as needed for mission. 380 Isp & up to 50% thrust/weight improvement over time. Merlin thrust/weight doubled from V1, but Raptor is closer to optimum.
— Elon Musk (@elonmusk) May 25, 2019