Good idea making this a separate thread.One small correction: according to Tom Mueller (source: http://hobbyspace.com/nucleus/?itemid=31499 ) the chamber pressure is 1410 psi (not 1420).
My guesstimate is that your way off on the weight of the Merlin. It should be closer to 1700-2000 pounds IMHO.
Since the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified. VAC Thrust / T/W = engine weight155,000lbf / 160:1 = 968.75lb or 440kgThe one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed.
Quote from: oldAtlas_Eguy on 08/10/2011 09:02 pmSince the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified. VAC Thrust / T/W = engine weight155,000lbf / 160:1 = 968.75lb or 440kgThe one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed. The Fastrac engine was just shy of 2000lbs. Sorry don't see that many published weight savings.
Quote from: Prober on 08/10/2011 09:29 pmQuote from: oldAtlas_Eguy on 08/10/2011 09:02 pmSince the weight value shown is a calculated value and was not a stated value attributed to Mueller but was calculated from two values that were stated it is listed as a reasonable value but unverified. VAC Thrust / T/W = engine weight155,000lbf / 160:1 = 968.75lb or 440kgThe one item of unknown here is it is not known whether the T/W is referencing SL or VAC. VAC being the worst case and one normally used so that was assumed. The Fastrac engine was just shy of 2000lbs. Sorry don't see that many published weight savings.FastacThrust (v): 60klbfisp (v): 315sWeight: < 2000lbT/W > 30:1Merlin 1DThrust (v): 155klbfisp (v): 310sWeight: 970lbT/W: 160:1Not much improvement, eh? I would trade 1.6% isp for that T/W difference.
Revealing several new details of the 1D, Tom Mueller, propulsion engineering vice president, says the engine is designed to produce 155,000 lb. vacuum thrust and have a chamber pressure at “the sweet spot” of roughly 1,410 psia. “We’ve also increased the nozzle expansion ratio to 16 [compared with 14.5 on the Merlin 1C],” says Mueller, who adds that the initial engine “is doing better than we hoped.” The engine is designed for an Isp (specific impulse) of 310 sec. and has a thrust-to-weight ratio of 160:1. “We took structure off the engine to make it lighter. The engine we shipped [for test] to Texas was a development engine and hopefully the production engines will be even better,” he says.The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We’ve added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It’s going to be a 1D with the same turbopump.”
This in an avleak article: http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2011/08/08/AW_08_08_2011_p27-354586.xml&headline=SpaceX%20Plans%20To%20Be%20Top%20World%20Rocket%20Maker&channel=defenseQuoteRevealing several new details of the 1D, Tom Mueller, propulsion engineering vice president, says the engine is designed to produce 155,000 lb. vacuum thrust and have a chamber pressure at “the sweet spot” of roughly 1,410 psia. “We’ve also increased the nozzle expansion ratio to 16 [compared with 14.5 on the Merlin 1C],” says Mueller, who adds that the initial engine “is doing better than we hoped.” The engine is designed for an Isp (specific impulse) of 310 sec. and has a thrust-to-weight ratio of 160:1. “We took structure off the engine to make it lighter. The engine we shipped [for test] to Texas was a development engine and hopefully the production engines will be even better,” he says.The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We’ve added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It’s going to be a 1D with the same turbopump.”
Gwynne said SpaceX will make 100 engines total in 2011. I'm quite at a loss here, considering the COTS-2 mission will consume only 10 engines, what will they do with the remaining 90 units? They're producing almost an order of magnitude more engines than they are consuming.So that leads to a big question, has there been any indication Spacex is planning to sell rocket engines to any other entities?
I'd want more context for that to know what she meant. If she's counting Dracos, then each Dragon mission uses 28.
There is very little public information that I am aware of, but I'm curious about the performance we might expect of a MVac 1D.My speculation is that the expansion nozzle probably can't grow that much, when the improved expansion ratio is the source of some of the 1D's improved ISP.How much of the ISP improvement comes from the higher chamber pressure versus greater expansion?