SpaceX (general discussion)

FighterJock said:
Fingers and Toes crossed that Starship Flight 9 does not explode this time Michel Van. Let's see if SpaceX has mannaged to sort the issues that plagued the last test launch.
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It is interesting that they seem to have got the "hard" part figured out (catching a booster) but Starship is taking longer. Then again, considering what it's being asked to do, it makes sense that it would. Once they get it figured out though, and they will, oh boy are things going to get interesting.
 
FighterJock said:
Fingers and Toes crossed that Starship Flight 9 does not explode this time Michel Van. Let's see if SpaceX has mannaged to sort the issues that plagued the last test launch.
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it depends if they get the POGO issue under control.
but i fear that those hardware modification happens from Starship 36 onwards,
and IFT-9 is launch in hope to get 35 close to Orbit.
 
Michel Van said:
it depends if they get the POGO issue under control.
but i fear that those hardware modification happens from Starship 36 onwards,
and IFT-9 is launch in hope to get 35 close to Orbit.
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Do we actually know it's a POGO issue? Has SpaceX said as much?
 
sferrin said:
Do we actually know it's a POGO issue? Has SpaceX said as much?
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They talk during countdown of IFT-8 about oscillation and Harmonic frequency in feed lines aka POGO

But it could also be ice that forms inside Methane feed line as pass true LOX tank.
and this methane Ice get into Turbopumps...
 
The name of the SpaceX capsule recovery vessel that pulled crew-9 out of the drink is "MV Megan," which was made in Alabama.

One of two, as per the wiki.

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On the Starship front...

Isar is to go with the Hank Hill favorite propane, somewhere between methane and RP (I have heard it described by Brian in the comments section at Space News' article on Isar):

"10% heavier than methane per BTU, but 3 times denser, so fuel tanks could be 1/3 smaller."

Any reason for Elon not to use that hydrocarbon? Less steel, less draggy surface area...
 
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publiusr said:
The name of the SpaceX capsule recovery vessel that pulled crew-9 out of the drink is "MV Megan," which was made in Alabama.

One of two, as per the wiki.
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And how is that relevant?
publiusr said:
Isar is to go with the Hank Hill favorite propane, somewhere between methane and RP (I have heard it described by Brian in the comments section at Space News' article on Isar):

"10% heavier than methane per BTU, but 3 times denser, so fuel tanks could be 1/3 smaller."

Any reason for Elon not to use that hydrocarbon? Less steel, less draggy surface area...
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Cost and easier to get. And propane can't be generated on Mars.
 
publiusr said:
Isar is to go with the Hank Hill favorite propane, somewhere between methane and RP (I have heard it described by Brian in the comments section at Space News' article on Isar):

"10% heavier than methane per BTU, but 3 times denser, so fuel tanks could be 1/3 smaller."

Any reason for Elon not to use that hydrocarbon? Less steel, less draggy surface area...
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pro-pain and pro-pain accessories.jpg

propane.jpg
 
publiusr said:
Any reason for Elon not to use that hydrocarbon? Less steel, less draggy surface area...
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There is no propane on Mars
SpaceX want to use the mars C02 and Water Ice to make Methane to fuel Starship return trip.

one question, if propane has so much advantage, why is not used by rocket companies ?
 
I am struggling to think of any rockets that USED propane.

And a quick google search finds me nothing beside a quote of it having a lower specific impulse then methane.

So that the likely reason if anything...
 
Firefinder said:
I am struggling to think of any rockets that USED propane.

And a quick google search finds me nothing beside a quote of it having a lower specific impulse then methane.

So that the likely reason if anything...
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And considering the stuff they've tried over the years, I'd think there must be something about propane that causes everybody to steer clear. Though I don't know what that might be off the top of my head.

From "Ignition!"

"Two space-storable systems have been investigated rather intensively. RMI and JPL, starting in 1963 or so, and continuing into 1969,
worked out the diborane-OF2 system, while Pratt and Whitney, Rocketdyne, and TRW, with NASA contracts, as well as NASA itself,
have concentrated their efforts on OF2 and the light hydrocarbons: methane, ethane, propane, 1-butene, and assorted mixtures of these.
(In most of their motor work, they used a mixture of oxygen and fluorine as a reasonably inexpensive surrogate for OF2.) AU the hydrocarbons were good fuels, but methane was in a class by itself as a coolant, transpiration or regenerative, besides having the best performance. The OF2-methane combination is an extremely promising one. (It took a long time for Winkler's fuel of 1930 to come into its
own!)"
 
Firefinder said:
I am struggling to think of any rockets that USED propane.

And a quick google search finds me nothing beside a quote of it having a lower specific impulse then methane.

So that the likely reason if anything...
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There was the CXV Quick reach 2 Booster proposed by T/Space in 2004.
it has to be a air launched propane pressure fed 2 stage rocket.
It do even subscale drop test together with Burt Rutan.
They offer the CVX capsule with 4 people to the ISS for 20 million If you must believe that.
 
Starship can keep the methane for ISRU.
If SuperHeavy used propane, might that reduce slosh? No ISRU considerations for first stages.

Starship needs methane to also serve as a coolant.
 
publiusr said:
Starship can keep the methane for ISRU.
If SuperHeavy used propane, might that reduce slosh?
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No. Then the vehicle will have to have two different engines, additional GSE and tanks, different loading processes, etc
Propane will have more slosh issues since it is more dense
 
9 days Turnaround for Falcon Booster:
A Falcon 9 rocket lifted off from California's Vandenberg Space Force Base Friday at 2:49 a.m. EDT (0649 GMT; 11:49 p.m. on March 20 local California time), on the NROL-57 mission for the U.S. National Reconnaissance Office (NRO).

This rocket's first stage also lofted the SPHEREx space telescope and PUNCH solar probes for NASA on March 11, according to a SpaceX mission description. NROL-57 was therefore the booster's second launch in a little over nine days, besting the previous Falcon 9 turnaround record of 14 days.
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www.space.com

SpaceX sets new rocket-reuse record on launch of US spy satellites (video)

A Falcon 9 first stage flew for the second time in just nine days early Friday morning (March 21).
www.space.com www.space.com
 
Byeman said:
No. Then the vehicle will have to have two different engines, additional GSE and tanks, different loading processes, etc
Propane will have more slosh issues since it is more dense
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Do you know why propane doesn't appear to have been used as a rocket fuel?
 
Far well Highbay
it's demolition began
GmhOKsfW0AEpIi9
 
Until recently, the high-altitude destruction of satellites was not a concern. The amount of spacecraft debris was relatively small compared to debris from naturally occurring meteorites.
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But by 2030, the global satellite population is expected to exceed 60,000, and thousands of spacecraft will be re-entering the atmosphere and burning up each year. With each satellite weighing as much as a small car, it all adds up. We are conducting research on the problem, and our early estimates are that around 3,500 tonnes of aerosols will be added to the atmosphere each year by 2033.
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Aerosols are tiny particles suspended in the air. They can play an important role in Earth’s climate, either cooling or warming it depending on their type and colour. Light-coloured particles generally reflect incoming sunlight and cause cooling, while darker particles, usually containing soot, absorb sunlight and make the atmosphere warmer.

Some of these aerosols are particularly worrying. In 2023, US scientists discovered particles containing various metals, including aluminium and lithium, in the stratosphere. These particles originated from spacecraft and debris such as the disposable rocket boosters attached to them. When spacecraft burn up during re-entry, they release chemicals such as metal oxides and nitrogen oxides.
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theconversation.com

Thousands of satellites are due to burn up in the atmosphere every year – damaging the ozone layer and changing the climate

The number of satellites is exploding, and we still don’t have a fully safe way to dispose of them.
theconversation.com theconversation.com
 
ALPHA TECH is speculating that back-pressure from hot staging might be the culprit.

Maybe solid ullage rockets could be affixed to the ring and discarded with it? Just for the time being.

I seem to remember talking about how a first stage helped support heavy Atlas payloads that would crush Centaurs.

Maybe stand this concept on its head?

Thrust ring stiffens Starship's tail--ring has solids for staging.

Ring falls away from Starship with an even lighter tail section--since pins for recovery are well forward. Hot staging ring has film around vent slots to keep sea level pressure--that pop/melts when ullage ignites for a gentler cork-sep.

Thoughts?
 
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publiusr said:
Maybe solid ullage rockets could be affixed to the ring and discarded with it? Just for the time being.


Thrust ring stiffens Starship's tail--ring has solids for staging.
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Again, throwing crap at the wall to see what sticks, but missing the wall,.
Any solution, even temporary, has to been within Spacex's mantra and hence no solids.
they don't have SRM engineers, facilities, siting or processes. It wouldn't be a quick fix anyways.
 
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Have the hot staging ring be part of Starship.
Solids are a long the outside of the ring.

The ring might help reduce weight in Starship's aft section--since standard Starship cannot land on its tail... perhaps weight savings can be had.

Shuttle SRB 's were load bearing right?
 
publiusr said:
Have the hot staging ring be part of Starship.
Solids are a long the outside of the ring.

The ring might help reduce weight in Starship's aft section--since standard Starship cannot land on its tail... perhaps weight savings can be had.

Shuttle SRB 's were load bearing right?
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Solids? Keep staging ring attached to Starship?

jRm8q5.gif
 
David from Space News I presume.

The ring would be dropped after staging...the ring would have ullage solids meaning the SS Raptors have a more benign environment.

SuperHeavy would have some distance such that it doesn't hit Starship with exhaust and vice versa.

Maybe the ring can slide to the side in segments.
The Gemini Titans staged in a nasty way--maybe panels can fly off similarly.

The Saturn V interstage ring was similar to what I described...but what did those guys know about LV development as compared to Elon the Great and Terrible?
 
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publiusr said:
The Saturn V interstage ring was similar to what I described...but what did those guys know about LV development as compared to Elon the Great and Terrible?
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they knew nothing about reuse or cost much like your comments.
Why can't you understand no solids and no expendable hardware
 

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