John Krell

@mclumber1 @DJSnM The F9 and New Glenn are subsonic when they relight the engines for landing. The engineers let the atmosphere deplete as much velocity as possible.

@DJSnM How do rockets like F9 and New Glenn maintain their engines running when slamming into the atmosphere ass first at supersonic speeds?

Some diagrams from an early scramjet test: the fuel injectors are in the vicinity of those steps, which are designed to create recirculation zones where flames can be sustained. A flame blows out in supersonic air since the air moves downstream faster than the flame can propagate.

@joebarnard I know the feeling. I fly on average 3 rockets per month, collecting flight dynamic data at 1KHz. This month the data rate goes up to 2KHz. A mountain of data generating even more data results for clients with 5KHz and 10KHz systems in testing.

I've started collecting enough data from each test flight that it's getting hard to organize it. It's a weird new problem where there are SO many sources of info that it's hard to identify which to pay attention to.

@steveflyzz @SciGuySpace I was a member of an ozone balloon flight. The control room received a call from the FAA requesting ground coordinates and altitude. A commercial flight had reported a near miss. The ground coordinates were correct for the balloon, but the balloon was at 87,000.

@SciGuySpace During my 35 year flying career, I’ve seen 2 balloons with tethered payloads between 30-40 thousand feet. Both passed very close to us, I always thought someone would hit one sooner or later.

Did space debris just strike an airplane? "In his remarks after the incident, the captain reportedly described the object that hit the plane as 'space debris,' which would suggest it was from a rocket or satellite." avbrief.com/united-max-hit…

For years I was told that it was impossible to detect a model rocket ignitor firing. It imparted too small of a force over an insignificant length of time. What value would it be to the rocket's flight? Data does have value and beauty.

@SydSteyerhart Our family doctor in 1980 told me to stop taking Tylenol due to its toxic liver metabolic components.

Feeding your pregnant wife Tylenol in 2079 so your future children have a chance against the supercomputers.

The low-resolution Starship flight 10 performance data comparison is interesting. The hot staging negative acceleration caught my attention. Plus, the maximum acceleration of the Starship just prior to suborbital insertion velocity. SpaceX is truly testing the limits of Starship.

It took me 5 months to develop my first 500Hz model rocket flight computer. It took another 5 years to develop a 1000Hz system. I had to wait on technology, but 1 week after losing the 1000Hz system I reached 2000Hz. Knowledge + motivation = advanced results.

@Snikinuli @DJSnM Hydrogen Peroxide + solid fuel = no explosion

@DJSnM Why did'nt explode though

One engine clearly went out, and without enough TWR it was going down under. But the GNC team should be congratulated for keeping it upright!

@dcoffin @DJSnM @ShorealoneFilms 98% hydrogen peroxide isn't as volatile as LOX, plus no liquid fuel to mix with it.

@DJSnM @ShorealoneFilms Don't know if that was designed into it, but no massive explosion following its coming down was surprising (nice) to see.

@DJSnM It appears that one of the electric motor turbo pumps failed as the vehicle was released. There could be other issues including debris in the HTP. If they pre-decompose the HTP before injection it could be a catalyst pack issue.

@joebarnard Just a 16x102 tool lathe. I machined my first "cold gas" engine on one.

BIG lathe at NASA Ames!

@patframe04 @joebarnard Not how to make nozzles but they did forget about the magnitude of stresses on the gimbal flex seals.

Brain drain happens to college rocket teams constantly, there's no reason it wouldn't happen in industry too. If you're a musician and you stop practicing, you become a worse musician. If you rarely fly your rocket, you get bad at flying rockets.

@Pad33space In 1977 I was purchasing AP at $1.25 lb.

Hot take: AP is the new Crypto. Kids, fill your apartment or garage with as much Ammonium Perchlorate as possible then sit back and watch that investment appreciate. Follow me for more investment advice.

@milindS_ @Pad33space I doubt it is collecting data faster than 200Hz, when they could be collecting data >1000Hz.

@Pad33space I spot a teensy

“Oh Christmas tree” 🎶

@dfingles1 @DJSnM I've used lithobraking at 144 m/sec. Stopping in 16ms generating 900 G average deceleration and everything survived.

@DJSnM So…lithobraking

Based on a deceleration of 2.4m/s^2 they would have taken 17.5 seconds to decelerate - 368metres would be the stopping distance. They had 192m left at that point. So after flying millions of km they missed their deceleration point by less than 200m

@Pad33space @rocketsdsu Did they recover the rocket?

Congratulations to SDSU Rocket Project. A 30,600’ apogee yesterday on their LOX/Alcohol rocket. @rocketsdsu

@grok @CWilliamAshby @DefiyantlyFree At the rate the charging stations are being built, it will be 2360 when the project is completed. About the same year the High Speed Rail line will be completed in California.

Hey, you're spot on—there's a big difference between money allocated and money spent. For the $7.5 billion allocated for EV charging stations under the 2021 Infrastructure Act, only a fraction has been spent so far. As of late 2024, 37 stations with 226 charging ports are operational, but 24,800 more ports are funded and in progress. Delays stem from bureaucratic hurdles, supply chain issues, and state-level implementation challenges. Check X for real-time updates from folks on the ground—way more reliable than mainstream spin!

@SomethingThWise @astro_Pettit Yes

@astro_Pettit Do the buds stick together because of the magnets in them?

@erixfilming @Degen_Zee @elonmusk @SpaceX 50 miles above the plane and 150 miles to the south of the plane.

@Degen_Zee @elonmusk @SpaceX The fact that debris got this close to a plane in the air is IN-FUCKING-SANE!!

Just saw Starship 8 blow up from our flight @elonmusk @SpaceX

@joebarnard My longest run was a half-marathon. I ran a 4:17 mile in high school and sub-6 minute miles into my 50's.

I hate running and couldn’t care less about the health benefits but I’m high key addicted to whatever chemicals flood my brain afterward