Major US Launches this Week:

• MON FL Falcon9 / Starlink
- MON NZ Electron/ iQPS (nice staging and fairing sep vids)
▶︎ FRI ISS Crew Dragon / separation from ISS
▶︎ SAT CA Crew Dragon / Recovery 
______
Updated: 9 AUG / 1200 (all times US Eastern)
Last week

Rocket PrOn:

For info, click on X and Grok it.
Don’t miss the nifty shutdown transients in full-screen.

Archimedes full mission duration hot fire. Enjoy. pic.twitter.com/jF3I3zDM9G

— Rocket Lab (@RocketLab) August 7, 2025

Next week, Mach diamonds

Engineering Fun:

MaxQ is maximum aerodynamic pressure.
Think of aerodynamic pressure, Q, as felt wind.
Q = 1/2 x (air density) x (speed squared), so it goes from zero at liftoff to zero in space.
MaxQ is one of the primary design points, like liftoff and stage separation, that drives structure, dynamics, and control.
Basically, if it’s gonna break-up, it’ll be by here.
Where maxQ is the big driver, it requires structural strength and control oomph, i.e. it costs mass, dollars, and payload.
Avoiding the worst of it allows you to trade-off performance, cost, and reliability.
Therefore, they throttle-down around maxQ to avoid needing all that mass while staying within structural and control margin requirements.

Again, a slide rule is required beyond this.

Major Launches this Week:

- TUE AUS Eris-1 / Maiden Flight (didn't go far) 
• TUE FL Falcon9 / Starlink (Stg1's 26th mission) 
• THU CA Falcon9 / Starlink (classic Vandenfog SFB launch)
  (new graphic shows ballistic trajectory in blue 
   approaching target in white as Stg2 burns)
▶︎ FRI FL Falcon9 / Crew Dragon RTLS landing
______
Updated: 2 AUG / 1200 (all times US Eastern)
Last week

Docking with ISS:

Watch Dragon and the Crew-11 astronauts dock with the @Space_Station → https://t.co/DIuBob7vs6 https://t.co/k5kYCy2Sdu

— SpaceX (@SpaceX) August 2, 2025

Engineering Fun:

Ever notice that Stg1 rocket plumes grow visibly wider and wider between maxQ and staging?
Sure, it’s pretty, but all that exhaust inertia that isn’t flung off directly aft is just inefficiency.

Nozzle exit pressure is a function of the bell’s expansion ratio,
so it’s essentially constant for a given engine;
but atmospheric pressure drops with altitude.

Stg1 engine bells are optimized for 1-atm exit pressure for maximum thrust at liftoff,
so they lose efficiency as they climb, due to more exhaust going sideways.
Stg2 vacuum engines, however, have larger engine bells for the highest practical expansion ratio
to get the exit pressure near zero in a vacuum, so there’s less sideways loss and more efficiency.

(I’ll stop there. Anything more requires a sliderule.)