Author Topic: SpaceX McGregor Testing Updates and Discussion (Thread 4)  (Read 531538 times)

Online Herb Schaltegger

https://twitter.com/jswartzphoto/status/1565513892679372800

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An interesting end to this Raptor 2.? test
@SpaceX
 McGregor yesterday.  Whatever is was, it sure ended with a BANG!  SpaceX loves testing the Raptor to the extreme on the tripod stand.  🚀🔥
See it in 4K and subscribe at http://tinyurl.com/jswartzYT

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@FelixSchlang

The black smoke streaming down after the hard shutdown/failure/whatever were almost delightfully anticlimactic. I’d love to see the remains of that engine.
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Offline Okie_Steve

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #741 on: 09/02/2022 02:15 pm »
The shock diamonds are clearly visible for the first 5 seconds or so then seem to suddenly "stretch" as I assume they throttle the Raptor up. My impression is the stretching continues very slowly for the next 30 seconds but what I think are the diamonds seem very blurry. What's up with that?

Online Herb Schaltegger

The shock diamonds are clearly visible for the first 5 seconds or so then seem to suddenly "stretch" as I assume they throttle the Raptor up. My impression is the stretching continues very slowly for the next 30 seconds but what I think are the diamonds seem very blurry. What's up with that?

Mach diamonds are a visible artifact that basically demonstrate “correct” fully-expanded flow. That is to say, the engine operating at pressure conditions that provide mass-flow rate and operating pressure through the throat that expands smoothly along the nozzle profile to the exit plane. The nozzle profile for a specific engine is optimized to produce those conditions based on ambient pressure. A vacuum-optimized nozzle is therefore generally larger (wider, longer) than one optimized for sea-level operation. Since first stages of rockets start at sea-level or thereabouts but climb into the upper atmosphere before staging, they usually have nozzles that lean toward the sea-level end of the optimization spectrum but still a bit wider/longer than might otherwise be required at sea-level in order to gain a bit more efficiency through the entire flight regime. Space shuttle SSME’s are a good example of this. By contrast, RaptorVacs that we’ve seen installed on Starship are rather shorter and less-wide than might be expected for a fully vacuum-optimized engine, but that’s because they have to fit under a skirt in a clustered configuration alongside sea-level optimized gimbaling Raptor engines.

So anyway. in a test where the shock diamonds start off well-defined but then fade, stretch or dissipate, we can infer that SpaceX are stating the engine at its optimized, baseline conditions for the nozzle, but then the engine begins operating outside of those parameters: pressure is changing, either due to throttle or mixture settings, perhaps both. I didn’t see a bright flash of green, so probably not oxygen-rich, or not too much so to cause combustion chamber oxidation and burning.
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Offline Robotbeat

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #743 on: 09/02/2022 04:05 pm »
Technically, you won’t have shock diamonds if the exit pressure is identical to atmospheric pressure.
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Online Herb Schaltegger

Technically, you won’t have shock diamonds if the exit pressure is identical to atmospheric pressure.

A forum post isn’t a substitute for a college-level class in the thermodynamics and compressible flow mechanics of a rocket engine operating at steady-state, let alone one (intentionally, I gather) operated dynamically to induced destruction. :)
« Last Edit: 09/02/2022 04:08 pm by Herb Schaltegger »
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Offline Okie_Steve

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #745 on: 09/02/2022 05:41 pm »
On the topic of intentional test to destruction, what are the likely candidate methods to cause such?

No obvious green flash so probably not running lean/oxygen rich

I would not expect running fuel rich to be much of a problem unless it somehow caused stability issues?

Slow pressure boost of the turbo pump(s)? The perceived 30 second creeping stretch until BOOM might support that.

Holding tongue wrong  ::)

Something else?

Offline edzieba

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #746 on: 09/02/2022 06:18 pm »
Technically, you won’t have shock diamonds if the exit pressure is identical to atmospheric pressure.
You'll still have shock diamonds even then because you'll still have shockwaves in the exhaust flow, because regardless of static pressure your flow is still supersonic (regardless of static pressure dynamic pressure will be enormous). Both underexpansion and overexpansion will produce shocks and mach discs, just with a different initial distance from the lip of the nozzle bell (distance and spacing will also vary with exhaust velocity). Unless your rocket engine is so spectacularly awful it underperforms a plastic bottle rocket and cannot achieve supersonic exhaust flow at all:

On the topic of intentional test to destruction, what are the likely candidate methods to cause such?

No obvious green flash so probably not running lean/oxygen rich

I would not expect running fuel rich to be much of a problem unless it somehow caused stability issues?

Slow pressure boost of the turbo pump(s)? The perceived 30 second creeping stretch until BOOM might support that.

Holding tongue wrong  ::)

Something else?
Overspeed a pump, limit coolant, close a propellant valve too much or too fast, open a propellant valve too much or too fast, limit crossover flow between the preburners (unbalanced operation), cut ignition in one or both preburners, poke it with a sharp stick, look at it at a funny angle, etc. The bottled inferno you're squeezing out the nozzle would very much like to squeeze out through the rest of the engine too, and will do so the moment you stop carefully and actively controlling the engine to prevent that.
Pump overspeed is probably the most preferable option, as it is the best way to ensure the highest energy RUD by adding the most energy to the system beforehand, and gains you valuable "what do the sensor outputs look like immediately before it gets melty" data.

Offline alugobi

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #747 on: 09/02/2022 06:19 pm »
Maybe a different metal mix in one of the spinny parts.

Offline su27k

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #748 on: 09/03/2022 03:48 am »
https://twitter.com/jswartzphoto/status/1565513892679372800

Quote
An interesting end to this Raptor 2.? test
@SpaceX
 McGregor yesterday.  Whatever is was, it sure ended with a BANG!  SpaceX loves testing the Raptor to the extreme on the tripod stand.  🚀🔥
See it in 4K and subscribe at http://tinyurl.com/jswartzYT

🎦 Me for WAI Media
@FelixSchlang

Interesting reply to this:

https://twitter.com/DutchSatellites/status/1565808908161228800

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That was one very nicely contained kaboom. No secondaries coming from the stand. No leaks. Looks like the new containment cans are doing their jobs.

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #749 on: 09/11/2022 09:14 am »


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The cows of McGregor have nearly become oblivious to the daily barrage of explosions, firings, other projects SpaceX's test facility is known for. Watch as multiple Raptor engines are tested to failure while these adorable creatures continue to graze the Texas fields.

Video and Pictures from Adam (@AdamCuker) and McGregor Live. Edited by Brady (@TheFavoritist).

All content copyright to NSF. Not to be used elsewhere without explicit permission from NSF.

Offline catdlr

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #750 on: 09/11/2022 09:44 am »
Those cows really settled down from the Hopper Days

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Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #751 on: 09/14/2022 05:05 am »
https://twitter.com/AdamCuker/status/1569868780670488578

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SpaceX in McGregor, TX tested 10 different static engine fires today for a total of 875 seconds. This included Raptor 2, Merlin, M/Vac, Stage 2, and SuperDraco engines.

Watch LIVE or Recorded at:
http://nsf.live/mcgregor

#Raptor #Merlin #SuperDraco
@NASASpaceflight

What’s McGregir going to be like if SpaceX get near 100 launches next year?!

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #752 on: 09/18/2022 09:34 am »

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #753 on: 09/25/2022 09:29 am »


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SpaceX's Vertical Raptor Stand Enables Rapid Test Firings

NASASpaceflight
25 Sept 2022

SpaceX test fires every single engine they produce in order to ensure a safe mission for its many payloads. For Raptor 2s, a commonly used stand is the vertical Raptor test stand. With two seperate testing bays, engines can be fired and swapped out in rapid succession for eventual fitment onto a Booster or Starship. Stands like these are crucial to getting Starship orbital as soon as possible.

Video and Pictures from Adam (@AdamCuker), Gary Blair, and McGregor Live. Edited by Brady (@TheFavoritist).

All content copyright to NSF. Not to be used elsewhere without explicit permission from NSF.

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #754 on: 09/27/2022 08:27 pm »
https://twitter.com/nextspaceflight/status/1574857580190396417

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Falcon static fire coming up at McGregor.

nsf.live/mcgregor

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #755 on: 09/27/2022 09:19 pm »
twitter.com/alexphysics13/status/1574868679803674634

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SpaceX completed today a 77 second static fire test of B1076, a Falcon booster, at their McGregor Test and Development Facility in Texas. If data looks good, it'll be transported to Florida for its first flight.

Replay with commentary: nsf.live/mcgregor

https://twitter.com/alexphysics13/status/1574868992904265730

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This booster will begin its career in November as a Falcon 9 booster but will eventually fly as a Falcon Heavy side booster on the Echostar XXIV mission currently scheduled for launch in Q1 2023.

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #756 on: 09/29/2022 03:27 pm »

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #757 on: 10/02/2022 09:19 am »
New F9 booster tested


Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #758 on: 10/09/2022 09:08 am »

Offline FutureSpaceTourist

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Re: SpaceX McGregor Testing Updates and Discussion (Thread 4)
« Reply #759 on: 10/12/2022 02:57 pm »
https://twitter.com/jswartzphoto/status/1580206358552793088

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Raptor roars at sunrise!  Beautiful early morning test from vertical stand with wind pushing exhaust back.   Nice little surprise at the end 😉   Go checkout the replay on the pano cam for full effect at nsf.live/mcgregor

@NASASpaceflight

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