Keep the engine small enough such that the components can be fabricating using common CnC mills ...
Merlin 2 has probably been mostly abandoned for the time being.
There have been talks about a "Merlin II" engine in the 1.2~1.7 million lbs thrust class. The only justification for such an engine is to reduce the recurring cost of launching F9s and FHs, as well as reduce the total number of engines used in possible Super HEavy Lift vehicles to some sane number.However, to this regard a 330,000 lbs class engine might actually be an optimal compromise. Let's call this (hypothetical) engine the "Griffon" and look at what it does:-Griffon 1AFuel: RP-1/LOXIsp (SL): 278 secsIsp (Vac): 312 SecsDry Mass: 2,200 lbsThrust-to-Weight Ratio: 150:1Thrust (SL): 313,000 lbsThrust (Vac): 330,000 lbs* A F1.1 core will need 4 engines instead of 9 (56% reduction in engine count)* A FH will need 12 engines instead of 27* In a cross fed FH you can have 100% cross feed via adjacent feeding* A 110 ton class LV will need 27 engines (no more than the current FH)* All the above configurations will have reasonable engine out capability which a single engine core will lack* The engine will still be small enough that the components can be made on standard CnC mills like the Merlin 1* The engine is a good match for an enlarged FH upper stage whereas an F1 class engine is notThe idea achieves three ends while offering a greater than 50% reduction in engine count. Keep the engine small enough such that the components can be fabricating using common CnC mills and be compatible human muscle handling -- preferably the same equipment and procedures used for Merlin 1s. Concentrating on efficient mass production may actually be cheaper than building a smaller number of very big engines which may be difficult to construct because of special machinery and handling requirements. Also, because will still have a quartet of engines on the Falcon 9 and twelve on an FH a good degree of engine out capability is maintained. Finally, the FH can really use an expanded upper stage 2~3 times heavier than the F9. An engine with about 2.3 times the Merlin 1D's thrust is a good match for such an upper stage.
Quote from: Idiomatic on 06/28/2012 01:13 amMerlin 2 has probably been mostly abandoned for the time being.It was never in the cards.One maverick, who has now left the company, gave one presentation about his personal ideas once, and then got publicly disavowed, get over it.
I was trying to play nice.
Quote from: Idiomatic on 06/28/2012 01:27 amI was trying to play nice.Oh, sorry.
Quote from: dwightlooi on 06/28/2012 01:02 amKeep the engine small enough such that the components can be fabricating using common CnC mills ...Since I've seen CnCs as small as my microwave and as big as my house, I'm wondering on what this statement is based.
Out of curiosity are you referring to Vozhoff or Tom Markusic?
Quote from: Idiomatic on 06/28/2012 01:13 amMerlin 2 has probably been mostly abandoned for the time being.It was never in the cards.
Quote from: QuantumG on 06/28/2012 01:17 amQuote from: Idiomatic on 06/28/2012 01:13 amMerlin 2 has probably been mostly abandoned for the time being.It was never in the cards.I do believe it was in the cards - but only as a part of a SpaceX bid for SLS contract(s).
F9 works. F9v1.1 will probably work better. FH is probably going to work as well. No need to muck with any of that unless you are Elon Musk and want to retire on Mars. To me the best hypothetical engine development thread around is the Methane staged combustion engine. It makes a ton more sense to me than a Griffon concept.
Quote from: Lars_J on 06/28/2012 02:27 amQuote from: QuantumG on 06/28/2012 01:17 amQuote from: Idiomatic on 06/28/2012 01:13 amMerlin 2 has probably been mostly abandoned for the time being.It was never in the cards.I do believe it was in the cards - but only as a part of a SpaceX bid for SLS contract(s).Yes, except SpaceX had roughly zero chance of winning those contracts, as was quickly made apparent to them. "Never in the cards" thus was a true statement before SpaceX even realized it.
Merlin 2 and BFR seem like they would be pretty useful for taking thousands and thousands of colonists and/or vacationers to Mars.
The NK-33 would seem to meet most of those requirements. I'm not sure how many of them are in existence, or if SpaceX could find a way to manufacture them in house.
Quote from: Brian Copp on 06/29/2012 02:11 amThe NK-33 would seem to meet most of those requirements. I'm not sure how many of them are in existence, or if SpaceX could find a way to manufacture them in house.Kuznetsov built about 200, of which Aerojet has 40. SpaceX would develop its own staged-combustion engine rather than use old Russian ones, I'm sure.