I am not an expert on rockets or foreign policy, but I think the fact that these engines are Russian is over-blown. It certainly makes some sense to have an all US fall-back for DoD payloads, but the fact of the matter is that the Russians make some good engines.I personally prefer to have some mutually beneficial economic ties for lower impact vehicles like Antares. It may give governments leverage but it also serves to add some pressure to play nice.
Quote from: DanielW on 11/05/2014 01:17 amI am not an expert on rockets or foreign policy, but I think the fact that these engines are Russian is over-blown. It certainly makes some sense to have an all US fall-back for DoD payloads, but the fact of the matter is that the Russians make some good engines.I personally prefer to have some mutually beneficial economic ties for lower impact vehicles like Antares. It may give governments leverage but it also serves to add some pressure to play nice.If (heaven forbid) we were to have a major invasion overseas, or a war, precipitated by Russia then the sanctions we have seen so far will ultimately lead to a total ban by one side, then the other, on imports & exports. That's a worst case scenario, and leverage would not be the biggest factor on the world stage. In this case, the spaceflight companies (and American Government/military) have the most to lose by not gaining access to a necessary part to their rocket or putting a payload to orbit. For Russia, it's only money that they can disperse for compensation.
I think he means Oxidiser/Fuel ratio, i.e. the AJ-26 runs oxidiser-rich, while the Merlin 1D runs fuel-rich. As a result, they'd have to move the bulkhead so as to carry more fuel and less oxidiser.
Quote from: Prober on 11/04/2014 01:10 pmGuyz we are drifting off the topic of a changeover to another engine "On October 19, 2012, NPO Energomash announced that three days earlier, an experimental RD-193 engine completed its fifth live firing without leaving test bench No. 2 at the company's NIK-751 test facility. During five tests, the engine burned for a total of 678 seconds. Following the tests, the engine was to be disassembled and checked for any defects to clear it for further tests, NPO Energomash said."http://www.russianspaceweb.com/rd193.htmlmaybe someone can focus on the history and see if this engine has a flight history?RD-193 is the youngest sibling from the RD-191 Subfamily. RD-191 is gimbaled variant and RD-193,intended for Soyuz core stage, is fixed variant and is surround by the four nozzles of the Soyuz core stage steering engine. RD-193 has not been flown to date as it was in development cycles.
Guyz we are drifting off the topic of a changeover to another engine "On October 19, 2012, NPO Energomash announced that three days earlier, an experimental RD-193 engine completed its fifth live firing without leaving test bench No. 2 at the company's NIK-751 test facility. During five tests, the engine burned for a total of 678 seconds. Following the tests, the engine was to be disassembled and checked for any defects to clear it for further tests, NPO Energomash said."http://www.russianspaceweb.com/rd193.htmlmaybe someone can focus on the history and see if this engine has a flight history?
Dont' the 4 steering nozzles share the same turbopump with the main nozzles, which means the steering nozzles are part of the main engine?
Quote from: nimbostratus on 11/05/2014 03:00 amDont' the 4 steering nozzles share the same turbopump with the main nozzles, which means the steering nozzles are part of the main engine?No. It's a separate engine with four nozzles, RD-0110IIRC Soyuz-2-1v doesn't even have enough thrust to leave the ground without it (using NK-33)
Are you sure?
Cygnus is also meant to supply the ISS. If the state of affairs with Russia deteriorates to a degree where Russia no longer supplies engines for this purpose me somehow thinks the purpose itself will fall away, too.If it happened now, after all, the US could not even send astronauts to ISS anymore, after all.This is an international project depending heavily on Russia. You no longer want to play with Russia? No need for CRS/Cygnus anymore so no need to secure any "all US" (nonsense anyway, you always have _some_ stuff coming from abroad) supply of engines.
And it occurs to me that RD-0110 was an upper stage engine for early soyuz LV. Perhas some modification has been made for use in atmosphere.
RD151 is developed for Naro use only?Why bother develope so many new engines?
Quote from: nimbostratus on 11/05/2014 05:24 amRD151 is developed for Naro use only?Why bother develope so many new engines?AIUI, RD-151 was developed in such a way as to comply with MTCR.For info on KSLV/Naro, see:http://russianspaceweb.com/kslv.html
Quote from: baldusi on 11/04/2014 08:21 pmQuote from: Coastal Ron on 11/04/2014 07:37 pmDon't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.Different O/F, different isp, different cycle (you have to deal with the gas generator output), different TVC, different diameters... etc. Save for the thrust nothing similar.Same oxidizer and fuel - LOX/RP-1 - otherwise I wouldn't have mentioned it as a possibility.
Quote from: Coastal Ron on 11/04/2014 07:37 pmDon't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.Different O/F, different isp, different cycle (you have to deal with the gas generator output), different TVC, different diameters... etc. Save for the thrust nothing similar.
Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Quote from: mr. mark on 11/01/2014 06:41 pmWouldn't it just be easier to go with a solid ATK first stage? They are already using or will use a ATK 30XL for the second. ATK has a good track record.The launch safety criteria for solids violate overpressure in case of failure at the MARS pad IIRC, and would most likely never be given a waiver by FAA, NASA or anyone else. That means a new pad, probably not at MARS.
Wouldn't it just be easier to go with a solid ATK first stage? They are already using or will use a ATK 30XL for the second. ATK has a good track record.
-snips-Athena 2cS with six boosters would lift 4.19 tonnes to a 500 km x 28.5 deg LEO ...It is a number that bumps up close to Delta 2 and Antares capability. ...
Quote from: a_langwich on 11/01/2014 07:03 pmQuote from: mr. mark on 11/01/2014 06:41 pmWouldn't it just be easier to go with a solid ATK first stage? They are already using or will use a ATK 30XL for the second. ATK has a good track record.The launch safety criteria for solids violate overpressure in case of failure at the MARS pad IIRC, and would most likely never be given a waiver by FAA, NASA or anyone else. That means a new pad, probably not at MARS.Minotaur V already launches next to the Antares pad. What makes you think a Castor 120-based rocket, like AthernaII or an Orbital/ATK equivalent, wouldn't be allowed? If a RSRM Castor 900 or single-segment Dark Knight was proposed (AthenaIII) I could see an argument, but not these.Quote from: edkyle99 on 10/27/2013 04:12 am -snips-Athena 2cS with six boosters would lift 4.19 tonnes to a 500 km x 28.5 deg LEO ...It is a number that bumps up close to Delta 2 and Antares capability. ...