SpaceX Starship : Texas Prototype(s) Thread 23 : Discussion

[robot_enthusiast]

My understanding, is that to save weight, the start-up hardware for the outer engines has been transferred to the OLM.  Therefore, is the static fire of an outer ring B7 engine a technical first?  I'm not sure I understand how the OLM to Booster transfer works. 

For a 20 second static fire, are initial propellants provided by the OLM and then propellant feed is transferred to the Booster?  Or does the OLM only provide pressurized gas to spin-up Raptor, but propellant is always provided by the Booster?

I don't know whether the startup software/controllers for the outer ring Raptors is on the booster, or the OLM...but in either event, has a previous rocket system technically proven this capability...or has this static fire been a first time demonstration?

I suspect that some sort of testing rig for this exists at McGregor, but I don't know its configuration or how it relates to the OLM configuration.

From my understanding, the controller for each engine is mounted directly to the side of the powerpack. The startup sequence would be performed by the engine controller using valves on the engine side. I would be willing to bet that the valves on the Raptor QD arms are just binary control, and would all close together right before the arms retract.

[rsdavis9]

My understanding, is that to save weight, the start-up hardware for the outer engines has been transferred to the OLM.  Therefore, is the static fire of an outer ring B7 engine a technical first?  I'm not sure I understand how the OLM to Booster transfer works. 

For a 20 second static fire, are initial propellants provided by the OLM and then propellant feed is transferred to the Booster?  Or does the OLM only provide pressurized gas to spin-up Raptor, but propellant is always provided by the Booster?

I don't know whether the startup software/controllers for the outer ring Raptors is on the booster, or the OLM...but in either event, has a previous rocket system technically proven this capability...or has this static fire been a first time demonstration?

I suspect that some sort of testing rig for this exists at McGregor, but I don't know its configuration or how it relates to the OLM configuration.

From my understanding, the controller for each engine is mounted directly to the side of the powerpack. The startup sequence would be performed by the engine controller using valves on the engine side. I would be willing to bet that the valves on the Raptor QD arms are just binary control, and would all close together right before the arms retract.

Yes! Keep as much as possible the same between outer raptors(no gimbal) and inner raptors.
The only difference is the supply of startup gases and electric. Either off or on.
Keep the same:
engine controller
main liquid propellant supply
etc.

[frith01]

My understanding, is that to save weight, the start-up hardware for the outer engines has been transferred to the OLM.  Therefore, is the static fire of an outer ring B7 engine a technical first?  I'm not sure I understand how the OLM to Booster transfer works. 

For a 20 second static fire, are initial propellants provided by the OLM and then propellant feed is transferred to the Booster?  Or does the OLM only provide pressurized gas to spin-up Raptor, but propellant is always provided by the Booster?

I don't know whether the startup software/controllers for the outer ring Raptors is on the booster, or the OLM...but in either event, has a previous rocket system technically proven this capability...or has this static fire been a first time demonstration?

I suspect that some sort of testing rig for this exists at McGregor, but I don't know its configuration or how it relates to the OLM configuration.

SpaceX already does a similar setup with Falcon 9 (just a lot less complicated.)   TEA/TEB for engine startup of outer engines is used only at the launch mount,  TEA/TEB for re-light of inner engines is carried aloft for orbital re-starts.

OLM provides different plumbing for the source of outer engine spin-up gases, so just the COPV & gas volume for startup of outer engines remains on the ground.

This was the first test of the new OLM plumbing for the raptor engine.  Each outer engine appears to have its own matching COPV in the mount, or maybe for each pair of engines.  Not sure if there is a good diagram for this yet.

 

[edkyle99]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

[livingjw]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

- Anything over halfway around the world is effectively orbital from a delta V point of view.

John

[meekGee]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

It's "orbital energy" and that was discussed often enough.

"Suborbital" is misleading since those arcs are low-energy and therefore short, usually nowadays not even accomplishing what a booster stage does on a regular flight - e.g. BO and VG.

[alugobi]

For a 20 second static fire, are initial propellants provided by the OLM and then propellant feed is transferred to the Booster?  Or does the OLM only provide pressurized gas to spin-up Raptor, but propellant is always provided by the Booster?

Since this was a test of autogenous pressurization, I think it's safe to assume that the propellants came from the booster tanks.

[edzieba]

For a 20 second static fire, are initial propellants provided by the OLM and then propellant feed is transferred to the Booster?  Or does the OLM only provide pressurized gas to spin-up Raptor, but propellant is always provided by the Booster?

Propellants are always from the Booster tanks, never from the OLM. The OLM provides support and startup gasses (purge, chill, and spinup) but not propellant.

[baking]

For a 20 second static fire, are initial propellants provided by the OLM and then propellant feed is transferred to the Booster?  Or does the OLM only provide pressurized gas to spin-up Raptor, but propellant is always provided by the Booster?

Propellants are always from the Booster tanks, never from the OLM. The OLM provides support and startup gasses (purge, chill, and spinup) but not propellant.

Just to clarify, the spinup gases are oxygen and methane, correct?  The explosion on July 11 was during a spinup test.

[edkyle99]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

- Anything over halfway around the world is effectively orbital from a delta V point of view.

John

If it doesn't complete an orbit, it can't be "orbital".  Close on delta-v, sure, but not an orbit.  It won't be officially tracked and listed as an orbital object.  See AS-202 etc. for example.  You won't find it in TRW Space Log, etc.  Same with VV04.

 - Ed Kyle

[Herb Schaltegger]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

- Anything over halfway around the world is effectively orbital from a delta V point of view.

John

If it doesn't complete an orbit, it can't be "orbital".  Close on delta-v, sure, but not an orbit.  It won't be officially tracked and listed as an orbital object.  See AS-202 etc. for examples.  You won't find them in TRW Space Log, etc.

 - Ed Kyle

Call it whatever you want, then. How ‘bout Almost But Not Quite Orbital But Could Be Orbital If We Wanted To Risk Uncontrolled Reentry Test Flight? Sadly, ABNQOBCBOIWWTRURTF doesn’t just flow off the tongue. 🙄

[ThatOldJanxSpirit]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

- Anything over halfway around the world is effectively orbital from a delta V point of view.

John

If it doesn't complete an orbit, it can't be "orbital".  Close on delta-v, sure, but not an orbit.  It won't be officially tracked and listed as an orbital object.  See AS-202 etc. for examples.  You won't find them in TRW Space Log, etc.

 - Ed Kyle

Call it whatever you want, then. How ‘bout Almost But Not Quite Orbital But Could Be Orbital If We Wanted To Risk Uncontrolled Reentry Test Flight? Sadly, ABNQOBCBOIWWTRURTF doesn’t just flow off the tongue. 🙄

Why does this matter? It’s a test flight that will generate data near equivalent to an orbital flight. The rest is semantics.

[Herb Schaltegger]

Why does this matter? It’s a test flight that will generate data near equivalent to an orbital flight. The rest is semantics.

Thank you for underscoring my point.

And please trim your quotes. If nothing else, people trying to read on mobile devices will thank you.

[Robotbeat]

Ed can be forgiven because he runs (well, used to run) a website that includes orbital or suborbital categorization so he needs an objective definition (I think orbital energy is appropriate actually, but whatever).

I’d pitch in $20 to help keep it running. Was a fantastic resource.

[hoku]

<snip>
If it doesn't complete an orbit, it can't be "orbital".  Close on delta-v, sure, but not an orbit.  It won't be officially tracked and listed as an orbital object.  See AS-202 etc. for example.  You won't find it in TRW Space Log, etc.  Same with VV04.

 - Ed Kyle

Vostok 1: launch at 63.342 deg East, landing at 45.997 deg East ... just saying ... 

(admittedly, Gagarin was at orbital velocity, and used retrorockets to slow down)

[meekGee]

Whoa there.  The one up there now may not be, and probably isn't, the flight article.  "Close" might be a tad bit optimistic. 

For both sides of the argument they haven't reached the stage to declare either way. B7/S24 is still, per all official parties, the current assigned serials for OTF-1.

"OTF"?  It isn't an "orbital" test.  It's more like Apollo Saturn 202, a suborbital trajectory aiming for the Pacific Ocean.

 - Ed Kyle

- Anything over halfway around the world is effectively orbital from a delta V point of view.

John

If it doesn't complete an orbit, it can't be "orbital".  Close on delta-v, sure, but not an orbit.  It won't be officially tracked and listed as an orbital object.  See AS-202 etc. for example.  You won't find it in TRW Space Log, etc.  Same with VV04.

 - Ed Kyle

I didn't say it was officially "orbital".  I said it's orbital energy, which is a perfectly clear and meaningful distinction.

I also said that "suborbital" is misleading, not that it was technically false.

You can mince words all you want, but from an engineering perspective, the planned SS flight profile is equivalent to being orbital. It is intentionally cut short for logistical reasons.

You can have a flight profile that shoots straight up past the moon and comes back without completing a single orbit and yet far exceeds orbital velocity, reentry speed, and therefore difficulty.  Still "suborbital"?  Technically, yes. Practically?  No.

[menomos]

<snip>
If it doesn't complete an orbit, it can't be "orbital".  Close on delta-v, sure, but not an orbit.  It won't be officially tracked and listed as an orbital object.  See AS-202 etc. for example.  You won't find it in TRW Space Log, etc.  Same with VV04.

 - Ed Kyle

Vostok 1: launch at 63.342 deg East, landing at 45.997 deg East ... just saying ... 

(admittedly, Gagarin was at orbital velocity, and used retrorockets to slow down)

Do we have any guess what the Delta-V difference is between something like Vostok 1 (with 181km perigee according to wikipedia's source doc) and the "Almost but not-quite orbital so we know it will re-enter over the Pacific" flight of Starship?

Just curious how close in Delta-V is being discussed.

[wannamoonbase]

Let me do something crazy and bring this back to a discussion of the Starship Prototypes in Texas.

The new flatter forward domes made up of gores look fantastic.  They just look better, smoother, less weld lines, likely easier to manufacturer.

The rapid iteration and flight testing of the SN's really move things along.

Having the freedom to break things really opens up a world of possibilities.

[Nomadd]

Call it whatever you want, then. How ‘bout Almost But Not Quite Orbital But Could Be Orbital If We Wanted To Risk Uncontrolled Reentry Test Flight? Sadly, ABNQOBCBOIWWTRURTF doesn’t just flow off the tongue. 🙄

 I like it. But I think it's already taken by a village in Wales.

[edkyle99]

You can mince words all you want, but from an engineering perspective, the planned SS flight profile is equivalent to being orbital. It is intentionally cut short for logistical reasons.

You can have a flight profile that shoots straight up past the moon and comes back without completing a single orbit and yet far exceeds orbital velocity, reentry speed, and therefore difficulty.  Still "suborbital"?  Technically, yes. Practically?  No.

Not mincing words, or making the choice myself.  These suborbital flights are important, and sometimes historic, but they are either given a COSPAR orbital designation or they aren't.   If so, they are on the orbital list.  If not, they aren't.

 - Ed Kyle