Fun & Curios

Stuff That’s Hard to Do (20-26 JUL)

Major US Launches this Week:

★ TUE FL Falcon9 / O3b mPower (nice vids)
★ WED CA Falcon9 / Tracers (RTLS @SLC-4W, me ol' stompin' grounds)
(cool vids of satellite deployments: two @ T+54m, T+1h35m, T+1h39m, four @ T+1h43m)
• SAT FL Falcon9 / Starlink 
• SUN CA Falcon9 / Starlink 
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Updated: 27 JUL / 0030 (times US Eastern)
Last week

Engineering Fun:

If you pay attention to the gauges on the lower RH and LH corners during Tuesday’s launch, you’ll see some interesting basic physics play out.

Acceleration goes from about 1.4g at launch to almost 4g at separation, due to the nearly constant thrust of the nine engines having less-and-less mass to push around as propellant is expended (F=ma or a=F/m so a~1/m) and less aero drag after maxQ.
When the single Stg2 engine lights, acceleration is even higher. Sure, the single Stg2 engine is optimized for vacuum operation, so it has a slightly higher thrust than any of the nine individual Stg1 engines; but the actual difference in acceleration is due to tossing-away all that Stg1 mass (see: rocket staging).

Next Episodes: Throttling back near maxQ, number of engines used, plus Stg1 return speed/altitude as gravity and drag have their way.

Homework Assignment: Watch the Stg1 speed and altitude gauges a few times and see if you can figure out what’s going on after separation.
(Yeah, I knowww… engineers get to do this all the time!)

Rocket PrOn: