AJ-1E6 (Now AR-1) Progress Known?

[TomH]

We have heard a little bit re. the test firings of the F-1 powerpack, and earlier this week Dynetics released a press report claiming "outstanding" progress on the F-1B: http://www.dynetics.com/news/347 including the fact that they are currently building propellant tanks at Marshall using friction stir welding.

Not much has been released about Aerojet's AJ-1E6 proposal (unofficially designated by some as AJ-1000). Does anyone have any information at all about the progress of this engine proposal? Obviously its heritage, which includes staged combustion, suggests a higher Isp than F-1B, though NASA could prefer the simplicity of the gas generator.

I do not know if the recent news out of ATK could portend ominously toward the destiny of their advanced solid proposal. Obviously both the casing and propellant differ, however successive de-bonding instances might raise doubts regarding systemic problems.

I also have to wonder whether Rocketdyne and Aerojet both will be allowed entries into the actual advanced booster competition now that AJ owns RD. The limited initial contracts regarding proposals were let when RD was part of PWR. I wonder whether the fact that Dynetics is the lead on the F-1B proposal will allow both to proceed in the actual competition, or whether AJ itself will decide that one engine has such an edge over the other that it decides to enter only one of them.  (Edit: F-1B is so big it likely has no other applications, while AJ-1E6 is sized such that it might actually be usable on an upgraded or Phase II EELV. With that and the higher iSP in mind, it could make sense to enter only that engine. OTOH, F-1B seems to be further along in development and perhaps less expensive and less risky to complete.)

On all these points, opinions are welcome, although facts are even better.

[Lobo]

I've heard nothing recently.  But would very much like to know too.

My -guess- is that since it's likely the AJ-1E6/AJ-1000 is a dual thrust chamber version of the AJ-500, and the AJ-500 is probably still only in development, that the AJ-1E6 is little more than a concept engine. Aerojet need to get 500klbs out of a single thrust chamber of the NK-33/AJ26 first.  I've not heard any thing recently on either of those fronts, but my guess is they are focusing mainly on making sure AJ26 gets some launches under it's belt on Antares before they do too much or talk too much about futer variants. 

They basically have a plan to increase the thrust of AJ26 from 394klbs thrust (vac) to 500klbs thrust (vac) (I'm assuming they are talking the vacuum thrust rather than the seal level thrust), and then a plan to put two thrust chambers together on a single turbopump like the RD-180.
They've probably studied the design of the NK-33 enough to know it was designed with a good margin and could handle an increase in thrust from 394k to 500k lbs with just some minor tweaking. And then two could be put together like the RD family. They feel it's within their capability to do to the basic engine.  But probably haven't done a whole lot towards that end just yet.  And there's no immediate need for it as the only LV to use the enigne has only one test flight under it's belt, and is designed to take two NK-33/AJ26's as they are. Going to two AJ-500's or one AJ-1E6 is probably an option OSC can look at for Antares, but they aren't looking to upgrade their fledgling rocket any time soon.

So, AJ-500 and AJ-1E6 are really probably just, "Yea, we can do that if there's a need...like the advanced booster competition".  But not too much more than that until there is said need for them.

That's just my wild speculation.

[MP99]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

cheers, Martin

[Downix]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

cheers, Martin

Ask ULA, which are using the twin-chamber RD-180 instead of twin RD-150's or 190's.

[MP99]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

Ask ULA, which are using the twin-chamber RD-180 instead of twin RD-150's or 190's.

But, RD-180 existed when ULA signed up for it.

If AJ26-500 is an "easy" upgrade from the Orbital variant, why then bother to make such a huge upgrade to a dual-thrust-chamber config?

Cheers, Martin

[Lobo]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

Ask ULA, which are using the twin-chamber RD-180 instead of twin RD-150's or 190's.

But, RD-180 existed when ULA signed up for it.

If AJ26-500 is an "easy" upgrade from the Orbital variant, why then bother to make such a huge upgrade to a dual-thrust-chamber config?

Cheers, Martin

Here's a possibility.

What will use the AJ-500 by itself?  As a stand alone engine (like the RD-191)?  Nothing that I'm aware of.

What could use two or more AJ-500's?
1) An ugraded Antares
2) An SLS Advanced liquid booster.

However, Antares would use 2 AJ-500's (one is not enough power), and one would use probably eight AJ-500's.
So is there much need for the AJ-500 by itself?  I don't know of any (although there could be and I just haven't heard about it).

But, is there a need for the AJ-1E6?
One of them on an upbraded Antares with a single gimbal, like RD-180 on Atlas.
Four of them on an SLS Advanced boosters, where they may not need to gimbal at all of attidute control is done with the RD-25's on the core.
Or four gimbals for the advanced booster if someone wanted to make a medium lift booster out of it.

Perhaps, Aerojet said, "Hey, this NK-33 has enough margin that we could up it's thrust to 500klbs pretty easily...cool!" Then shortly thereafter, "Hey, the only applications we see for a 500klb version of this is in pairs...why not simplify it by making an RD-180 like dual thrust chamber single engine out of it once we use up our existing stock of NK-33/AJ26 and start making them ourselves?  Two common thrust chambers and nozzles, and we just make a larger common turbopump (Aerojet has to make a new one anyway once their existing Russian hardware runs out). We have a 1000klb dual chamber engine that's lighter and cheaper than two separate 500klb single chamber engines."

Just a thought.  Perhaps it's wrong.  But if they didn't see a specific need for the single chamber 500klb engine, they might have thought to bypass it and go right to the dual chamber 1000klb one.

But I'm sure this is all evaluations going into whatever new production facility Aerojet will set up to make new ones when the Russian stock is out, and they are deciding if they want to make a single chamber AJ-500 or a dual chamber AJ-1000.

I don't know, but is a single larger turbopump cheaper to build that two smaller ones?  I'm guessing the cost of making a turbopump isn't much different between the two, so if you only need to make half as many, that could be a cost savings.  But that guess could be wrong.  :-)
Maybe there's just other advantages in going with the two chamber single engine rather than two separate engines.

[baldusi]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

Ask ULA, which are using the twin-chamber RD-180 instead of twin RD-150's or 190's.

But, RD-180 existed when ULA signed up for it.

If AJ26-500 is an "easy" upgrade from the Orbital variant, why then bother to make such a huge upgrade to a dual-thrust-chamber config?

Cheers, Martin

Yeah, but LM asked for the RD-180, doing half an RD-170, not one forth. The advantage is one of reliability, specially on th TP side. If you look at reliability numbers the difference between a small and a big turbopump is about the same. Thus, you almost halve your tp and start up failure modes (given that TP and turbo system start up are the main failure risk). Given that two engines have (basically) no engine out, you get better reliability overall.
Also, turbo machinery likes to be big. The NK-33 thrust chamber can do 135% easily. So, it's not strange that if they intended to redo the TP they would rather only do the big one. Let's look at the potential clients:
1) The original AJ-500 project was done to compete on the Air Force RLV project. Since it's cancelled, the original client is not there.
2) Antares. Could use the dual AJ-500, but an AJ-1E6 is probably preferred.
3) Atlas V. An AJ-1E6 is the only reasonable replacement for the RD-180.
4) SLS Advanced Booster. Look at the trades NASA did on ESAS and on replacing the SSRB with new solids vs one or two RD-170 per booster. The dual RD-170 gave a far better performance, but the risk was "unacceptable". Given the weight on risk than NASA has, the difference between three 1E6 and six 500 might be the deciding factor on the risk issue of their bid.
Thus, given that as far as we know it, both are still paper rocket, I wouldn's be surprised at ll that the AJ-500 is cancelled and they only advance on the AJ-1E6.

[TomH]

Given the weight on risk than NASA has, the difference between three 1E6 and six 500 might be the deciding factor on the risk issue of their bid.

I thought that AJ's proposal was to use 4 AJ-1E6 on each booster, which would be more thrust than Dynetics' Pyrios with 2 x F-1B. It would take 8 of the 500s to match 4 AJ-1E6, but 7 of them would be just shy of 2 F-1Bs. How many AJ-500s could fit on a 5.5m dia. base anyway: 6, 7, 8? Seems to be stretching things.

AJ could well have plenty of time, but unless AJ is keeping their work quiet and under wraps, Dynetics surely seems to be taking a lot more initiative.

[gospacex]

I thought that AJ's proposal was to use 4 AJ-1E6 on each booster, which would be more thrust than Dynetics' Pyrios with 2 x F-1B. It would take 8 of the 500s to match 4 AJ-1E6, but 7 of them would be just shy of 2 F-1Bs. How many AJ-500s could fit on a 5.5m dia. base anyway: 6, 7, 8? Seems to be stretching things.

I know a company which seems to have no probs launching a LV with 9 rocket engines on a 3.66 meter wide first stage. (ducks and runs)

[Prober]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

Ask ULA, which are using the twin-chamber RD-180 instead of twin RD-150's or 190's.

But, RD-180 existed when ULA signed up for it.

If AJ26-500 is an "easy" upgrade from the Orbital variant, why then bother to make such a huge upgrade to a dual-thrust-chamber config?

Cheers, Martin

may not be that huge an upgrade.   Take a look see at the early Titan engine, then look a the AJ26.    You can almost see Aerojet thinking using two thrust chambers off one shaft. 

[Prober]

So what would be the benefit of twin-thrust-chamber AJ-1E6 over just fitting 2x AJ26-500?

A little simpler? But at the expense of higher capacity components up-stream of thrust chambers.

T/W? But that's almost irrelevant for a booster.

Ask ULA, which are using the twin-chamber RD-180 instead of twin RD-150's or 190's.

But, RD-180 existed when ULA signed up for it.

If AJ26-500 is an "easy" upgrade from the Orbital variant, why then bother to make such a huge upgrade to a dual-thrust-chamber config?

Cheers, Martin

Also, turbo machinery likes to be big. The NK-33 thrust chamber can do 135% easily. So, it's not strange that if they intended to redo the TP they would rather only do the big one. Let's look at the potential clients:
1) The original AJ-500 project was done to compete on the Air Force RLV project. Since it's cancelled, the original client is not there.

What RLV project was this, and do you have a link to a pdf?
 

[newpylong]

I know a company which seems to have no probs launching a LV with 9 rocket engines on a 3.66 meter wide first stage. (ducks and runs)

Irrelevant really. Merlins are small enough physically and low enough thrust to cluster like that. They would be useless on a LRB.

[baldusi]

What RLV project was this, and do you have a link to a pdf?

The title of the RFI was "Reusable Booster System High Thrust Main Engine".

[gospacex]

I know a company which seems to have no probs launching a LV with 9 rocket engines on a 3.66 meter wide first stage. (ducks and runs)

Irrelevant really. Merlins are small enough physically and low enough thrust to cluster like that. They would be useless on a LRB.

Who said to put Merlins on LRBs?
I said if Merlins can be clustered x9, then AJ-500s can be clustered x9 too (on a wider stage, of course).

[newpylong]

I don't think you're getting it. Just because 9 150K lb, extremely light, and very small engines can fit close together - does not mean that a similar amount of 300-500K lb thrust engines can be clustered like that. There are weight issues, heat issues, among others. 5.5 M is not enough.

[gospacex]

I don't think you're getting it. Just because 9 150K lb, extremely light, and very small engines can fit close together - does not mean that a similar amount of 300-500K lb thrust engines can be clustered like that. There are weight issues, heat issues, among others. 5.5 M is not enough.

I don't see significant heat issues for regen cooled chambers and nozzles. It's not RS-68

F9 is 3.66 meter diameter.
Merlin's nozzle is 1.676 m diameter.
NK-33's nozzle is 2 m diameter (1.193 times wider than Merlin).

If NK-33s are to be mounted exactly the same way as Merlins on F9 but with all dimensions scaled by 1.2, the stage needs to be about 4.4 meters in diameter for them to fit under it.

Why do you think 5.5 m stage wouldn't be enough?

[Lars_J]

I don't think you're getting it. Just because 9 150K lb, extremely light, and very small engines can fit close together - does not mean that a similar amount of 300-500K lb thrust engines can be clustered like that. There are weight issues, heat issues, among others. 5.5 M is not enough.

F9 is 3.66 meter diameter.
Merlin's nozzle is 1.676 m diameter.
NK-33's nozzle is 2 m diameter (1.193 times wider than Merlin).

If NK-33s are to be mounted exactly the same way as Merlins on F9 but with all dimensions scaled by 1.2, the stage needs to be about 4.4 meters in diameter for them to fit under it.

Why do you think 5.5 m stage wouldn't be enough?

The Merlin nozzle diameter figure of 1.676m has to wrong. There would be no way of fitting 9 of them in a 3.66 diameter cylinder. The M1D nozzle diameter appears to be ~1.1m. (my estimate based on F9v1.1 photos)

[Lobo]

I don't think you're getting it. Just because 9 150K lb, extremely light, and very small engines can fit close together - does not mean that a similar amount of 300-500K lb thrust engines can be clustered like that. There are weight issues, heat issues, among others. 5.5 M is not enough.

I don't see significant heat issues for regen cooled chambers and nozzles. It's not RS-68

F9 is 3.66 meter diameter.
Merlin's nozzle is 1.676 m diameter.
NK-33's nozzle is 2 m diameter (1.193 times wider than Merlin).

If NK-33s are to be mounted exactly the same way as Merlins on F9 but with all dimensions scaled by 1.2, the stage needs to be about 4.4 meters in diameter for them to fit under it.

Why do you think 5.5 m stage wouldn't be enough?

If Aerojet proposes a 5.5m wide LRB for SLS that uses four AJ-1E6's, then that's 8 nozzles in 4 pairs.  Dunno if 9 would fit, but 8 will have to fit unless Aerojet goes with only 3 engines for 6 nozzles.

But it doesn't have to necessarily fit under the core.  The 5 F-1's didn't fit under the S-1C, which is why it had the nacels over the outter four engines (not sure if nacel is the right word, maybe "shroud")
The Dynetics booster will have that too as the two F-1B's won't fit under the 5.5m core either.  They will protrude out from the core on each side.

So if Aerojet needs to put four dual chamber AJ-1E6's at the four corners of the core with each protruding out somewhat, I'm sure they can.  As long as where it protrudes doesn't interfere with the SLS core.  THe Dynetics booster engines are at 90 degrees to the core interfaces.  With four engines, you migth have to basically make two pairs of them in a similar arrangement so they don't protrude in towards the core.  Then again it might not be a problem at the four corners.  Depends on how far they might protrude.

[newpylong]

I don't think you're getting it. Just because 9 150K lb, extremely light, and very small engines can fit close together - does not mean that a similar amount of 300-500K lb thrust engines can be clustered like that. There are weight issues, heat issues, among others. 5.5 M is not enough.

I don't see significant heat issues for regen cooled chambers and nozzles. It's not RS-68

F9 is 3.66 meter diameter.
Merlin's nozzle is 1.676 m diameter.
NK-33's nozzle is 2 m diameter (1.193 times wider than Merlin).

If NK-33s are to be mounted exactly the same way as Merlins on F9 but with all dimensions scaled by 1.2, the stage needs to be about 4.4 meters in diameter for them to fit under it.

Why do you think 5.5 m stage wouldn't be enough?

If the Merlin 1D's nozzles were 1.6 m diameter they would not come close to fitting underneath the F9 core. They are much closer to 1 m in size, about waist height on a person in pictures, and they fit under the core.

[baldusi]

Let me remind you that two F-1B would mean about 16MN and 270s/310s or so of isp. Three AJ-1e6 would be 13.35MN but with 297s/331s. It works better at three. When NASA did a trade between 1 x F1A, 2xF1A, 1xRD-170 and 2xRD-170 boosters to replace the SSRB, the RD-170 gave something like 15% extra performance to the F-1A. So, 20% extra thrust but 10% less isp means about equal performance (or better for highly elliptic).