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allforspace OP t1_j813qys wrote

If that was only half of the booster's thrust, imagine what full thrust will look like!

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collegefurtrader t1_j815zzt wrote

Nearly twice as much I guess

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__Osiris__ t1_j819zbj wrote

More than, since it will have 2 more engines.

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glhope t1_j81xig6 wrote

It’s trivia of course, but I’m curious to know if that amount of thrust is merely calculated or if there is a way to measure it. Is there a “rocket dynamometer”?

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Reliable_Redundancy t1_j828dmh wrote

There could be strain gauges on the pad, but I would imagine it's hard to calibrate them in situ.

More likely, they have lots of sensors on each engine including pressure transducers. They know from single engine tests that pressures in an engine are correlated to the amount of thrust it is producing. A little bit of math later they get the total thrust of the rocket

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amitym t1_j83vdkt wrote

Tbf you don't need to calibrate them very carefully to get an imprecise (though presumably accurate) figure like "7.9 million."

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Disastrous_Elk_6375 t1_j836fxc wrote

They're testing engines separately at the factory. They've ran hours of tests and most likely have a pretty solid understanding of what thrust each engine gives at a certain "throttle" level. So they'll have precise measurements of things like flow for each engine, and they'll know what each flow setting would translate into thrust. From there it's simple math and some approximation.

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Feggy_JVS t1_j82bsmv wrote

How much more thrust did it create compared to the next most powerful rocket?

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Borg8401 t1_j82dvri wrote

The most powerful currently active rocket design is the Space Launch System (SLS), operated by NASA (USA). The Block 1 model of the SLS, which generates a peak thrust of 36,786 kN (8.27 million lbf).-Guinness World Records, 2022

This test at 50% produced nearly equivalent thrust metrics.

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stevedonie t1_j81g75q wrote

So they used nearly all of the engines, but only achieved half of max thrust. Is that because they didn't throttle the engines to 100%, or is there some other reason?

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Anthony_Pelchat t1_j81gog3 wrote

Correct. Engines throttled down to around 50%.

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acksed t1_j81xss1 wrote

I thought it was a little too sedate for full thrust.

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Trifusi0n t1_j83j526 wrote

Me and you have different definitions of sedate…

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amitym t1_j83w12a wrote

Ah a thrust connoisseur I see.

Well spotted, I say, well spotted.

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RedditorFor8Years t1_j81zds5 wrote

Will they be doing 100% thrust, full mission duration test in the future?

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Shrike99 t1_j82bang wrote

I doubt the launch pad would survive such a test. I'm not sure there's a facility in the world that could.

The test stand at NASA's Marshall Center was able to handle the Saturn V first stage static firing for a similar duration to Superheavy (~2.5 minutes), but Superheavy's energy output is about 2.7 times greater.

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b-Lox t1_j83odv2 wrote

For such a test the limitation is not the thrust level, but the facility where it happens yes.

The Marshall test stand is specifically built for handling these kind of tests, with a huge flame diverter, and hold-down systems that are specific for the task.

It will not happen because they don't want to risk the launch table if there is a problem, but you can build the facility to handle the force, no problem. Just a question of funds, location and schedule, not thrust.

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amitym t1_j83wj5k wrote

Yeah right on.

To understand why it's no problem as this commenter said, remember that the thrust itself is comparable to forces easily within the usual realm of civil engineering tasks.

We don't use rockets to get to space because they generate cosmically far-fetched amounts of thrust, but rather because they can generate thrust reliably and continuously over an extended period, largely indifferently to the environment around them.

It's a similar principle as how a jet liner with engines capable of transporting hundreds of people at Mach 0.9 can be held in place by a couple of wooden chocks.

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actfatcat t1_j83r4fn wrote

2.5 minutes? My watch must be slow.

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rdhatt t1_j84x9rs wrote

~2.5 minutes is the total burn time of the Saturn V first stage engines after liftoff.

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Shrike99 t1_j860j84 wrote

S-IC nominal burn time is 150 seconds, or exactly 2.5 minutes.

Superheavy nominal burn time is 169 seconds, or 2.8 minutes.

Though that figure may have been for the 29 engine version, the 33 engine version might be a bit less since it burns fuel quicker.

Either way, it's close enough to the Saturn V that I think it's fair to call it a 'similar' duration.

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Anthony_Pelchat t1_j8234dd wrote

Not on the ground. Remember, even at this low amount of thrust, it was still more than the Saturn V produced when it sent humans to the Moon. Full mission duration isn't needed as each engine is already tested that way individually.

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Decronym t1_j836ti8 wrote

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

|Fewer Letters|More Letters| |-------|---------|---| |BFR|Big Falcon Rocket (2018 rebiggened edition)| | |Yes, the F stands for something else; no, you're not the first to notice| |ITS|Interplanetary Transport System (2016 oversized edition) (see MCT)| | |Integrated Truss Structure| |MCT|Mars Colonial Transporter (see ITS)| |SLS|Space Launch System heavy-lift|

|Jargon|Definition| |-------|---------|---| |Raptor|Methane-fueled rocket engine under development by SpaceX|

^(3 acronyms in this thread; )^(the most compressed thread commented on today)^( has 36 acronyms.)
^([Thread #8544 for this sub, first seen 11th Feb 2023, 07:55]) ^[FAQ] ^([Full list]) ^[Contact] ^([Source code])

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SwiftTime00 t1_j833kvv wrote

Somewhat out of the loop on current spacex news. What rocket is this for, it doesn’t look like the first stage of starship unless the design has changed? Or is it like an upgraded falcon heavy?

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synmotopompy t1_j8363v2 wrote

It's the Super Heavy - the first stage of the Starship which is the second stage.

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SwiftTime00 t1_j836ige wrote

Ok, that makes allot of sense, thought there was a new ship called super heavy that I had no clue about and was very confused lol. Didn’t realize they gave the first stage a different name than starship, thought the whole thing was just called starship and it would be stage 1 of starship and stage 2 of starship rather than separate names for both. Thanks for clearing it up for me.

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jamesbideaux t1_j838pqx wrote

the naming scheme is a bit odd, the full stack is called starship and the upper stage is also called starship.

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sosaudio t1_j85vhl1 wrote

They should call the full stack Jefferson’s Starship.

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butterbal1 t1_j834av0 wrote

First stage of the super heavy.

That cool thing that they were flying on 3 engines and bellow flopping before standing up and landing goes on top of this behemoth.

It is going to be VERY large.

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SwiftTime00 t1_j835tu0 wrote

So is super heavy a “new” (new to me) rocket separate to starship and falcon heavy?

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ilfulo t1_j836shr wrote

Super Heavy is the name of the first stage of the launch system called "Starship", which evolved in its design from the 2016 ITS and 2018 BFR. The second stage is also called "Starship" (hence the confusion, sometimes) which is stacked on top of super heavy.

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Barrrrrrnd t1_j81hkq7 wrote

I feel like they should do a full throttle hold down test for at least a few seconds to make sure they aren’t going to blow the pad apart while it’s fully stacked.

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dkf295 t1_j8248dt wrote

A 5 second test is already longer than the rocket will remain on the stand, and damage (thermal and otherwise) decreases exponentially as distance to the pad increases. Which is to say, by a couple seconds into the burn the rocket will be taking off, and by 5 seconds the rocket will be far enough from the mount for the thermal stresses and shockwaves will be less than the 50% intensity, 5 second burn.

Between this and the 10 second, 14 engine test back in November (which was done with inferior concrete that held up dramatically less well than the current 'crete they're using) it's safe to say they're fairly confident there will be no showstopping problems. It is also extremely likely they will have the water deluge system in place for the full launch which will further reduce any damage.

Finally even if they did completely wreck the pad, it's no biggie. Sure, it's not sustainable but this is a test campaign, and they've already re-done the pad several times.

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Loggerdon t1_j83r51s wrote

My friend Glen does driveways. He could be there tomorrow to bid them a new concrete launchpad. He would be there today but he has a hangover.

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sosaudio t1_j85w2z3 wrote

Glen is an animal. Just a fucking legend.

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ackermann t1_j82q45i wrote

Huh, it’s a new type of concrete since the 14 engine test fire? That’s reassuring

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Reddit-runner t1_j83yht1 wrote

Apparently not.

The "special concert" was spotted still in its bags a few days ago.

The new hypothesis is that SpaceX will completely remodel the area under the launch table after the frist flight. This will include a proper deluge system and the special concert.

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Reddit-runner t1_j83yxxg wrote

In addition to what others have already said: I suspect during a proper launch SpaceX will not give 100% throttle until the rocket has at least cleared to tower.

The super heavy booster with the ship on top has a thrust to weight ratio of about 1.6. This means they can throttle down to 75% and still get the rocket off the launch table.

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[deleted] t1_j81722i wrote

[deleted]

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New_Poet_338 t1_j8190qi wrote

That is what a full duration static test is. An aborted static test is not full duration.

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SteveMcQwark t1_j81a1m4 wrote

There's also full (launch) duration testing. Doing a full duration test with an engine is often about essentially simulating a launch, ensuring that you can sustain the performance you need for the requisite amount of time.

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New_Poet_338 t1_j81ar6v wrote

They did that for SLS but the first flight of SLS was a mock production flight. The first flight of SS will be a test flight. There is no chance the infrastructure at Boca Chica would survive that.

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Ryermeke t1_j817uo4 wrote

You sure it doesn't reach stage sep in 5 seconds?

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yahbluez t1_j81algl wrote

You really think that something that has minus 3.600 tons of weight will not go to orbit?

That will not only go to orbit, that will leave the earth gravity.

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