Welcome back to The MECO Newsletter! After over a year-long hiatus, we're thrilled to reignite the conversation on all things rocketry. In this special comeback issue, we dive into a recap of our recent posts on X (@RocketSimulator), highlighting exciting advancements in rocket engine development from the past three months. These updates showcase the ingenuity pushing propulsion technology forward, from historic Soviet legends to cutting-edge modern designs. Let's geek out together!
RD-107 and RD-108: Soviet Legends Still Powering Missions
We're totally geeking out over the RD-107 and RD-108 engines, the workhorses behind the R-7 family—from Sputnik in 1957 to Soyuz ISS missions in 2025. Developed by Glushko at OKB-456 (now Energomash), these kerosene-LOX gas-generator cycle engines boast over 2,000 flights with 99%+ reliability. RD-107 (for boosters): 810 kN sea-level thrust, 256 s ISP SL. RD-108 (core): 745 kN SL, up to 290 s burn time. These icons have outlasted empires!
Aquila Vac: Propane Power for Isar Aerospace's Spectrum
Let's talk about Isar Aerospace's Aquila Vac engine, delivering 94 kN vacuum thrust with propane and LOX. With an ISP around 340 s, its real strength is density ISP—propane's 0.58 g/cm³ density (vs. methane's 0.42) allows more impulse in smaller tanks, making rockets lighter and cheaper. It's like a punchy hatchback in the world of propulsion!
Feast your eyes on PLD Space's TEPREL-C engine, Europe's most powerful private rocket engine at 190 kN sea-level thrust (vacuum version: 75 kN). Using bio-kerosene and LOX in a gas-generator cycle, it's built for reusability with Europe's largest private turbopumps. Five on Miura 5's first stage deliver 950 kN liftoff, aiming for orbital flights in 2026. A decade of evolution from pressure-fed roots!
The BE-7 is a marvel: LH2/LOX dual-expander cycle with 44.5 kN vacuum thrust, throttling to 20%, ~450 s ISP, and additive manufacturing for efficiency. It's powering Blue Moon landers for Artemis. Compared to Raptor's brute force, BE-7 shines in precision for soft landings and ISRU. Competition is fueling progress!
The RD-170 flexes with 7.9 MN thrust from four chambers and one turbopump—oxygen-rich staged combustion at 245-250 bar, 337 s vacuum ISP, and 257,000 HP turbopumps. Ancestor to RD-180 and RD-191, it's proof of pushing physics to the limit.
Booster 18 Cryo Insights: Plumbing and Propellant Power
Diving into Booster 18's internals: 3,650 t propellant (2,925 t LOX, 725 t CH4), 1,374 t/min flow at liftoff, 3.6:1 O/F ratio, and pogo-tuned plumbing. The Nov 2025 rupture highlighted testing needs, but it's all about optimizing for scale.
Launcher’s E-2 set a 222 s endurance record with LOX/kerosene, ox-rich staged combustion, 101 bar pressure, and 2.75 mixture ratio. Cumulative run time: 1,128 s across 13 starts. Thrust: 10 tf, ISP up to 365 s vac. Impressive progress!
