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Honda conducts successful launch and landing of experimental reusable rocket

(global.honda)
1355 points LorenDB | 1 comments | 17 Jun 25 15:02 UTC | HN request time: 0.202s | source
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whatever1 ◴[17 Jun 25 16:02 UTC] No.44300677[source]▶
Question why is it so easy today to build reusable rockets? Is it because the onboard cpu speed of the chips can solve more granular control problems with low latency?
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roshdodd ◴[17 Jun 25 16:41 UTC] No.44301068[source]▶
As someone who actively works in the field, it was a culmination of:

- Advances in rocket engine design & tech to enable deep throttling

- Control algorithms for propulsive landing maturing (Google "Lars Blackmore", "GFOLD", "Mars Landing", and work through the references)

- Forward thinking and risk-taking by SpaceX to further develop tech demonstrated by earlier efforts (DC-X, Mars Landing, etc.)

Modern simulation and sensor capabilities helped, but were not the major enabling factors.

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bumby ◴[17 Jun 25 16:50 UTC] No.44301152[source]▶
Can you elaborate on the advances in deep throttling?
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1. briandw ◴[17 Jun 25 17:30 UTC] No.44301563[source]▶
Rocket engines struggle to throttle down to low levels due to combustion instability, injector dynamics, and turbopump limitations. Here are some stats on minimum throttle levels:

SpaceX Merlin 1D: ~40% Rocketdyne F-1 (Saturn V): ~70% Space Shuttle Main Engine (RS-25): ~67% Blue Origin BE-4: ~20–25%

Falcon 9 does the "hover slam" where they have to turn off the engine exactly at touch down, or the rocket starts to go back up again. Throttle is too high for the weight of the booster at that point in flight.