Could a new F-1x Engine open the door for an 8.4m kerolox core for SLS?

[Jim]

No reason in the world that PWR can't do an Inexpensive F-1 upgrade to “modern manufacturing technology”.   Sure any manufacturing SpaceX is doing could also be done by PWR, only issue for PWR is their overhead.

Today's premier U.S. kerosene rocket engine expertise resides in Hawthorne, not Canoga Park.

 - Ed Kyle

You give them too much credit Ed.   This will point you back in the right direction.

Nope, he is right

[Lars_J]

same thing. Some abbreviate AJ-26-500 to AJ-500.

Pardon me for not believing in the AJ-26-500 when they're still using NK-33s and changing the name.

You are not the only skeptic.

[baldusi]

You'd be wrong there Ed.  PWR still makes the RS-27A, which has higher performance than the Merlin.

Rocketdyne completed and test fired its last RS-27A in March 2006, more than six years ago.  It was the last engine tested at Santa Susana, a test site now deactivated.  A handful of surplus engines remain in storage. 

Merlin 1D beats RS-27A in specific impulse, thrust to weight ratio, and cost.  It should, because it is a modern design whereas RS-27A was derived from Rocketdyne's 1950's era "150K" engine.

 - Ed Kyle

And let me add, Merlin 1D also throttles AND (on some versions) can be restarted. Save for thrust, it's an absolutely superior engine. And in the worst case a dual Merlin 1D would give more thrust, higher isp, throttle capability AND weight less total. How can you say it's a higher performance engine?

[Downix]

You'd be wrong there Ed.  PWR still makes the RS-27A, which has higher performance than the Merlin.

Rocketdyne completed and test fired its last RS-27A in March 2006, more than six years ago.  It was the last engine tested at Santa Susana, a test site now deactivated.  A handful of surplus engines remain in storage. 

Merlin 1D beats RS-27A in specific impulse, thrust to weight ratio, and cost.  It should, because it is a modern design whereas RS-27A was derived from Rocketdyne's 1950's era "150K" engine.

 - Ed Kyle

And let me add, Merlin 1D also throttles AND (on some versions) can be restarted. Save for thrust, it's an absolutely superior engine. And in the worst case a dual Merlin 1D would give more thrust, higher isp, throttle capability AND weight less total. How can you say it's a higher performance engine?

Because you used two of them.

[ugordan]

You'd be wrong there Ed.  PWR still makes the RS-27A, which has higher performance than the Merlin.

Rocketdyne completed and test fired its last RS-27A in March 2006, more than six years ago.  It was the last engine tested at Santa Susana, a test site now deactivated.  A handful of surplus engines remain in storage. 

Merlin 1D beats RS-27A in specific impulse, thrust to weight ratio, and cost.  It should, because it is a modern design whereas RS-27A was derived from Rocketdyne's 1950's era "150K" engine.

 - Ed Kyle

And let me add, Merlin 1D also throttles AND (on some versions) can be restarted. Save for thrust, it's an absolutely superior engine. And in the worst case a dual Merlin 1D would give more thrust, higher isp, throttle capability AND weight less total. How can you say it's a higher performance engine?

Because you used two of them.

So... by that reasoning, an RS-68 is a "higher performance" engine because you can use one of them in place of two SSMEs.

[edkyle99]

Because you used two of them.

Two of them together weigh less than one RS-27A, but make nearly 300,000 pounds of sea-level thrust, half-again as much as RS-27A. 

Or consider an equal thrust comparison, roughly, of three RS-27A type engines versus four Merlin 1D engines.  The Merlin cluster would weigh less than 2/3rds as much as the RS-27 cluster, saving over a tonne of dry mass.

The wisdom of smaller engines becomes clearer to me over time.  Smaller engines can have bigger expansion ratios, for better specific impulse, for example.  They take up less vertical space, saving structural mass.  And so on.  Russia has efficient engines created by clustering smaller, but more efficient, chambers. 

 - Ed Kyle

[Downix]

You'd be wrong there Ed.  PWR still makes the RS-27A, which has higher performance than the Merlin.

Rocketdyne completed and test fired its last RS-27A in March 2006, more than six years ago.  It was the last engine tested at Santa Susana, a test site now deactivated.  A handful of surplus engines remain in storage. 

Merlin 1D beats RS-27A in specific impulse, thrust to weight ratio, and cost.  It should, because it is a modern design whereas RS-27A was derived from Rocketdyne's 1950's era "150K" engine.

 - Ed Kyle

And let me add, Merlin 1D also throttles AND (on some versions) can be restarted. Save for thrust, it's an absolutely superior engine. And in the worst case a dual Merlin 1D would give more thrust, higher isp, throttle capability AND weight less total. How can you say it's a higher performance engine?

Because you used two of them.

So... by that reasoning, an RS-68 is a "higher performance" engine because you can use one of them in place of two SSMEs.

I'm just pointing out that it is not an equal assertion.

And regardless, it is against the original assertion that *only* SpaceX can produce an RP-1 engine. PWR does make one, which has higher thrust, lower impulse, and lower T/W. It still is there, however.

[edkyle99]

PWR does make one, which has higher thrust, lower impulse, and lower T/W. It still is there, however.

PWR made one.  It still catalogs the engine, has some built and tested that could be shipped if the final Delta 2 rockets are ever built, but it no longer makes RS-27A or any other RP engine. 

 - Ed Kyle

[MP99]

The wisdom of smaller engines becomes clearer to me over time.  Smaller engines can have bigger expansion ratios, for better specific impulse, for example.  They take up less vertical space, saving structural mass.  And so on.  Russia has efficient engines created by clustering smaller, but more efficient, chambers.

However, SLS boosters (2x F-1A) or 8.4m core (4x F-1A??) would need 6x or 12x engines each.

Is there enough space to fit these within the diameter of the stages and constraints of LC-39's flame trench?

cheers, Martin

[Downix]

PWR does make one, which has higher thrust, lower impulse, and lower T/W. It still is there, however.

PWR made one.  It still catalogs the engine, has some built and tested that could be shipped if the final Delta 2 rockets are ever built, but it no longer makes RS-27A or any other RP engine. 

 - Ed Kyle

By that argument, they no longer make the RS-68 or RL-10 families either, as they only built them *when needed*. You are claiming that because they are not producing them right now, they no longer make them at all. This is not the case, as their other engines demonstrate. They produce the engines as-needed. Just because they are not producing them today does not mean they cannot produce them if a company were to order them.

So, your argument is still invalid.

[Lars_J]

Nonsense, Downix. Not the same situation. You are really going to compare an engine they haven't built for years (RS-27A) with an engine in active production (RS-68), not to mention the RS-68A in active development? I'm not sure when the last RL-10 rolled off the line - but with it being used by both EELV's -  I'm sure the last one wasn't delivered that long ago.

So just because one isn't coming off the production line *right now* (last month vs years ago) they are all in the same situation? C'mon, you know better. Don't dig deeper.

[Downix]

Nonsense, Downix. Not the same situation. You are really going to compare an engine they haven't built for years (RS-27A) with an engine in active production (RS-68), not to mention the RS-68A in active development? I'm not sure when the last RL-10 rolled off the line - but with it being used by both EELV's -  I'm sure the last one wasn't delivered that long ago.

So just because one isn't coming off the production line *right now* (last month vs years ago) they are all in the same situation? C'mon, you know better. Don't dig deeper.

The RS-68 engines being flown were delivered in '08, the RL-10's in '09. They purchase a large, known quantity in a bulk order. The Atlas has used up almost all of its backstock of RL-10's, hence the program to modify the Delta's RL-10's to work on the Atlas.

[Lars_J]

The engines being flown *now*, sure. But can you tell us when ULA received its newest RS-68 or RL-10? How many of each does PwR have on the order book that have yet to be delivered?

[Downix]

The engines being flown *now*, sure. But can you tell us when ULA received its newest RS-68 or RL-10? How many of each does PwR have on the order book that have yet to be delivered?

They are warehoused, just like the RS-27A's are for Delta II. No difference there. I do not have the figures on the due date for delivery, that is company confidential. But they are in an identical state, a pre-built number of units waiting for use.

[Prober]

PWR does make one, which has higher thrust, lower impulse, and lower T/W. It still is there, however.

PWR made one.  It still catalogs the engine, has some built and tested that could be shipped if the final Delta 2 rockets are ever built, but it no longer makes RS-27A or any other RP engine. 

 - Ed Kyle

By that argument, they no longer make the RS-68 or RL-10 families either, as they only built them *when needed*. You are claiming that because they are not producing them right now, they no longer make them at all. This is not the case, as their other engines demonstrate. They produce the engines as-needed. Just because they are not producing them today does not mean they cannot produce them if a company were to order them.

So, your argument is still invalid.

you and I are thinking alike on this.....replace "when needed" with per cutomer order.