Delta 4 Should Be Replaced by New Delta 5

[Steven Pietrobon]

I changed my mind. After re-reading the information available, I have come to believe that the RS-25D is just too complicated and thus too expensive. If it should turn out that they can simplify the design in the quest to make an expendable version, then find out it could still be reusable, I could reconsider.

RS-25E is the expendable version that is being developed right now for SLS. I'm not sure how reusable this engine is though.

[MATTBLAK]

Sadly, the RS-25 will never again be used on a reusable spacecraft.  It almost makes more sense to upgrade the RS-68 to a regenerative nozzle and more thrust. Combining that type of engine with a big cluster of GEM solids and a good upper stage would make for a formidable expendable launcher!

But not any cheaper than the Delta IV (which is VERY expensive), so I'm not sure I understand the point?

It was once suggested to me that it would be cheaper to upgrade and modify an in use and in production engine like the RS-68 than to modify and 'bring back from the dead' the RS-25, which is itself from a class of vehicle that is now a half-decade into museum life...

[Chasm]

In hindsight I'd skip the "fast and cheap" RS-68 for a reworked RS-25.
Switch to fabrication methods available in the 90s, integrate the improvements that were been developed at the time. Continue to improve over time.

Can't be much more expensive at the end of the day.

[Patchouli]

I changed my mind. After re-reading the information available, I have come to believe that the RS-25D is just too complicated and thus too expensive. If it should turn out that they can simplify the design in the quest to make an expendable version, then find out it could still be reusable, I could reconsider.

RS-25E is the expendable version that is being developed right now for SLS. I'm not sure how reusable this engine is though.

I figure the RS-25E should still be reusable since the main change is a switch to a lower cost but heavier channel wall construction.

Though the RL-10 was reused on the DC-X and they looked at reusing the H-1 on the Saturn I.

[edkyle99]

RS-25E is the expendable version that is being developed right now for SLS. I'm not sure how reusable this engine is though.

My understanding is that they did not go with a full RS-25E development program.  Instead, they are building more RS-25D engines with some incremental changes to reduce production cost.

 - Ed Kyle 

[Lars-J]

RS-25E is the expendable version that is being developed right now for SLS. I'm not sure how reusable this engine is though.

My understanding is that they did not go with a full RS-25E development program.  Instead, they are building more RS-25D engines with some incremental changes to reduce production cost.

 - Ed Kyle

That's my understanding as well, the RS-25E is right now a paper engine.

The RS-25 is tricky to start, and cannot be air-started. (nor re-started) So why would an *expendable* version of that engine be well suited for a reusable vehicle?  

[AncientU]

In hindsight I'd skip the "fast and cheap" RS-68 for a reworked RS-25.
Switch to fabrication methods available in the 90s, integrate the improvements that were been developed at the time. Continue to improve over time.

Can't be much more expensive at the end of the day.

How about designing and building a new engine?

And switch to fabrication methods from THIS century.
(The 1990s are 20 years dead and gone.)

[john smith 19]

RS-25E is the expendable version that is being developed right now for SLS. I'm not sure how reusable this engine is though.

My understanding is that they did not go with a full RS-25E development program.  Instead, they are building more RS-25D engines with some incremental changes to reduce production cost.

 - Ed Kyle

If I were of a cynical nature I would think this is excellent news. They've retained most of the performance and re-usability of the RS25 but with copies less than 30 years old (keeping in mind the issues when Orbital starting using refurbed NK33's on Antares).

That means a superb RLV engine will be available after the SLS is finally cancelled. IMHO SSME was the jewel in the crown of the STS programme. Unlike every other LRE (prior to SX and Blue's entry into the market) it was designed for reuse and had NASA implemented all the upgrades developed for it over the years (and a few obvious additions) it would have had a better T/W ratio while retaining the Isp (in fact perhaps with a bit better nozzle shape it might have even increased that).

But to the OP.

There will be a new Delta IV and Delta IV Heavy replacement.

It will be called Vulcan/ACES.  I'd say that's going to happen. Nothing short of having ULA shut down will stop Tory Bruno from pushing it forward.

[GWH]

How many firings is a SSME or Rs25 capable of before refurb? If less than 10 its not designed for real reuse.

[Lars-J]

How many firings is a SSME or Rs25 capable of before refurb? If less than 10 its not designed for real reuse.

And if it can't air-start or re-start (without lots of development), it's use for a reusable launch vehicle is even further limited.

Just let it die. Why are you hanging on to 40 year old engines (RS-25) or 20 year old engines (RS-68)? Yes it has great isp, but that is not everything.

[Chasm]

In hindsight I'd skip the "fast and cheap" RS-68 for a reworked RS-25.
Switch to fabrication methods available in the 90s, integrate the improvements that were been developed at the time. Continue to improve over time.

Can't be much more expensive at the end of the day.

How about designing and building a new engine?

And switch to fabrication methods from THIS century.
(The 1990s are 20 years dead and gone.)

My alternate history is skipping the RS68 in the 90s. Using production methods from 2010s to build an entirely different engine is a bit more complicated at that time. 


Today I would do a new engine.
That said buying a new engine in the US is something that needs a whole lot of thinking. Engine development does not have a stellar track record when it comes to questions like on time or on budget.
History is littered with 90 and 95% completed projects. Once you add more qualifiers into the mix there are very few engines left. "Flown at least once" seems to be a great acid test.

If there will be a new engine one of the first questions must be: Why hydrolox in a first stage?
Does not make much sense unless you do something like Ariane 5/6 and using solids does not really help in a reusable world.

[russianhalo117]

DELTA V

Six GEM-60 SRBs

Common Booster Core first stage with one RS-25D engine at 104.5%

5-meter Delta Cryogenic Second Stage with one MB-60 engine

5-meter composite payload fairing



DELTA V+

Eight GEM-60 SRBs

Common Booster Core first stage with one RS-25D engine at 104.5%

5-meter Delta Cryogenic Second Stage with one MB-60 engine

5-meter composite payload fairing



The dry masses of the CBC and DCSS are different because I subtracted the mass of the RS-68 and RL-10 by the dry mass of each stage respectively and to each of those numbers, I added the mass of the RS-25D and MB-60 engines.

I apologize if this does not make sense, but I did try my hardest to explain everything, envy887.

Strap-on version of GEM-60 SRM is nearing completion on its final-ever production run and its production line will be handed over to the GEM-63XL team. GEM-40/GEM-46 lines were updated and are currently being used for the standard version of GEM-63.

[envy887]

...
Today I would do a new engine.
That said buying a new engine in the US is something that needs a whole lot of thinking. Engine development does not have a stellar track record when it comes to questions like on time or on budget.
History is littered with 90 and 95% completed projects. Once you add more qualifiers into the mix there are very few engines left. "Flown at least once" seems to be a great acid test.

If there will be a new engine one of the first questions must be: Why hydrolox in a first stage?
Does not make much sense unless you do something like Ariane 5/6 and using solids does not really help in a reusable world.

Exactly. Hydrolox first stage only makes sense if the boosters rapidly reuseable (e.g. liquid with flyback or barge landing) and the main stage goes all the way to orbit AND BACK.

I don't think there's any reasonable argument to be made that an expendable hydrolox main stage with solid boosters will be commercially competitive.

[primer_black]

Boy and howdy!

It's a wonderfully compact ground start engine, perfect for a spaceplane! If you wanted to do a 1/3 scale carbon composite Shuttle variant, it would be the perfect technology base to start from.

And despite its great efficiency, it is not well suited for a reusable vehicle.

Stage you mean. As in powered landing meaning restart. Agreed. Would work great for reuse on a flyback where you don't restart.

Newer engines that are built with reusability in mind - M1D, BE-4, Raptor - are better choices for new rocket stages.  Can't we just let the RS-25 retire with honor instead of trying to use it where it doesn't make sense?

Agree with the highlight I've done.

FWIW, the only way I could see RS-25E derivative used would be with either an air launched/started or ground launched/started (with side boost) spaceplane concept (unlike Shuttle by having integral LH/LOX tanks).

add:
For a rapid deploy & recovery spaceplane single engine use *only*, there are some redesign/additive mfr/materials changes that could exploit hydrolox propulsion as originally intended for a vehicle in the capability class of the HL20. You could push it then well beyond the 108% thrust level.

The only advantage for such a vehicle might be a more rapidly reusable crew transport to LEO turnaround than Dreamchaser/Dragon/Starliner/derivative NS capsule.

This observation suddenly looks a lot more prescient in light of the announcement of the XS-1 award; Boeing will be partnering with AJR and flying an SSME-legacy main engine designated the AR-22:

http://forum.nasaspaceflight.com/index.php?topic=32829.msg1682477#msg1682477

Aerojet Rocketdyne, a subsidiary of Aerojet Rocketdyne Holdings, Inc. (NYSE:AJRD), was selected to provide the main propulsion for the Boeing and the U.S. Defense Advanced Research Projects Agency (DARPA) reusable Experimental Spaceplane (XS-1). Aerojet Rocketdyne is a member of the Boeing team that recently announced an agreement to collaborate with DARPA to design, build and test a technology demonstrator for the agency's XS-1 program.

The reusable experimental spaceplane is designed to deliver small satellites into orbit with high launch responsiveness. The main propulsion is based on the legacy space shuttle main engines (SSME).

"As one of the world's most reliable rocket engines, the SSME is a smart choice to power the XS-1 launch vehicle," said Aerojet Rocketdyne CEO and President Eileen Drake. "This engine has a demonstrated track record of solid performance and proven reusability."

For the XS-1 program, Aerojet Rocketdyne is providing two engines with legacy shuttle flight experience to demonstrate reusability, a wide operating range and rapid turnarounds. These engines will be designated as AR-22 engines and will be assembled from parts that remained in both Aerojet Rocketdyne and NASA inventories from early versions of the SSME engines. Assembly and ground testing will take place at NASA's Stennis Space Center in Mississippi.
http://spaceref.com/news/viewpr.html?pid=50920

[oldAtlas_Eguy]

The other engine Boeing was looking at was the BE-3. The now designated AR-22 was the only other plausible rapid reusable hydrolox engine available.

But the weight range of this vehicle to LEO puts it at the very low end (actually about half that of a DIV without solids) as a replacement and starts Boeing into a competition with a subsidiary that they 50% own.

If Boeing could scale this vehicle up into a larger Medium class vehicle by factor of 5. Then it could become that highly competitive LV to SpaceX and also if partnered with Dreamchaser could represent a very cheap personnel transport to LEO. Also a scale up by factor of 5 puts it into direct competition with Vulcan (and SpaceX for which it would be a peer in probably Price) for the the lower end payloads which actually outnumber the larger payloads.

Could Boeing if successful with this vehicle be contemplating selling their interest in ULA. This vehicle if successful could kill ULA unless ULA goes with creating a rapid reusable 1st stage vehicle.

[Dante80]

XS-1 would not be competing with Delta IV. Delta IV is finished, at least as far as he -M LVs are concerned. Also, it is a different beast, for a different application.

Regarding the program itself, it is an X- program. This means experimental and a technology demonstrator. Whether Boeing will decide to move on with the concept (a la X-33/Venture Star) will depend on a lot of things. And one of those is the fact that by the time you add 2-3 more SSMEs and a significant upper stage, the cost balloons to a territory they might not be comfortable with (at least as far as the commercial market is concerned).

Lets not get ahead of ourselves here.

[Patchouli]

The other engine Boeing was looking at was the BE-3. The now designated AR-22 was the only other plausible rapid reusable hydrolox engine available.

But the weight range of this vehicle to LEO puts it at the very low end (actually about half that of a DIV without solids) as a replacement and starts Boeing into a competition with a subsidiary that they 50% own.

If Boeing could scale this vehicle up into a larger Medium class vehicle by factor of 5. Then it could become that highly competitive LV to SpaceX and also if partnered with Dreamchaser could represent a very cheap personnel transport to LEO. Also a scale up by factor of 5 puts it into direct competition with Vulcan (and SpaceX for which it would be a peer in probably Price) for the the lower end payloads which actually outnumber the larger payloads.

Could Boeing if successful with this vehicle be contemplating selling their interest in ULA. This vehicle if successful could kill ULA unless ULA goes with creating a rapid reusable 1st stage vehicle.

I'm surprised Boeing didn't ask Northrop to dust off the TR-106 or TR-107 since it's not trying to be a SSTO and doesn't need an engine with as high of an ISP as the SSME.

The latter plus an expendable upper stage would be a near F9 v1.0 class LV.

[CaptainScarlett]

My "Lego Rocket" would be a Delta IV core with either an RS-25 or RS-68 main engine, 2 4 segment Space Shuttle SRB's, and a J-2X third stage (or ACES if that would be better). It would be for NSS and NASA use only.
Possibility of being built?  negative zero... 😆

[edkyle99]

What about 5-7 BE-3's on the Delta 5m core, with a BE-3 vacuum upper stage ACES?  That would be an all hydrolox vehicle, 1st stage may be able to land. 

Would need 6 or 7 BE-3 engines to match RS-68A liftoff thrust.  Nothing is known about BE-3 specific impulse or dry mass outside the halls of Blue Origin to my knowledge.  As a starting point, lets assume it could be configured to match RS-68A's ISP (360 sec SL/414 sec Vac).  An RS-68A weighs ~6,600 kg, so each BE-3 would have to weigh less than 940 kg (if seven were used) to match current Delta 4 CBC performance.  For comparison, Merlin 1D is believed to weigh 470 kg.  The BE-3U would have a bigger challenge matching RL10B-2, since the latter engine has ISP = 465 sec and only weighs ~300 kg including nozzle extension.

The primary benefit to this approach would be cost, rather than performance, although some performance gain might be possible.  Would seven BE-3 engines cost less than one RS-68A?  Would one BE-3U cost less than one RL10?  Would CBC stage recovery be possible?  Etc.

Fun to consider, but won't happen.  That said, it does make me wonder if a BE-3 boosted launch vehicle might be worth considering for small payload applications.

 - Ed Kyle

[envy887]

What about 5-7 BE-3's on the Delta 5m core, with a BE-3 vacuum upper stage ACES?  That would be an all hydrolox vehicle, 1st stage may be able to land. 

Would need 6 or 7 BE-3 engines to match RS-68A liftoff thrust.  Nothing is known about BE-3 specific impulse or dry mass outside the halls of Blue Origin to my knowledge.  As a starting point, lets assume it could be configured to match RS-68A's ISP (360 sec SL/414 sec Vac).  An RS-68A weighs ~6,600 kg, so each BE-3 would have to weigh less than 940 kg (if seven were used) to match current Delta 4 CBC performance.  For comparison, Merlin 1D is believed to weigh 470 kg.  The BE-3U would have a bigger challenge matching RL10B-2, since the latter engine has ISP = 465 sec and only weighs ~300 kg including nozzle extension.

The primary benefit to this approach would be cost, rather than performance, although some performance gain might be possible.  Would seven BE-3 engines cost less than one RS-68A?  Would one BE-3U cost less than one RL10?  Would CBC stage recovery be possible?  Etc.

Fun to consider, but won't happen.  That said, it does make me wonder if a BE-3 boosted launch vehicle might be worth considering for small payload applications.

 - Ed Kyle

Bezos has speculated about using New Shepard as a "BE-3 boosted launch vehicle" "for small payload applications". Making a multi-engine version could make sense for medium payloads.

BE-3U would have the advantage (in a potentially reusable system) of having about 6x the thrust of RL-10, which allows a much larger upper stage with lower staging and easier recovery of the core.