IF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?
Quote from: spacenut on 05/12/2015 02:15 pmIF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?Please see Hyperion5's post here.
Quote from: baldusi on 05/11/2015 01:52 amPlease review this pictures of the Angara-3 cross-feed preliminary design.Well I disagree with your comments about shortcomings with my design, I am glad you posted the Angara pictures. Without understanding Russian, it is clear that tank-to-tank cross flow is viable (which I didn't think it was). Clearly by pressurizing the outboard booster tanks and not the central ones, sufficient fuel will flow from the outboard tanks to the central ones to power the central engine. The diagram shows the central tanks remaining completely full.
Please review this pictures of the Angara-3 cross-feed preliminary design.
Quote from: Ben the Space Brit on 05/12/2015 02:47 pmQuote from: spacenut on 05/12/2015 02:15 pmIF, big if, they did make a Methane Merlin and directly replaced the kerosene on the Falcon 9, (of course they would have to adjust tank size via the common bulkhead), what kind of performance would the Falcon 9 and Falcon H have?Please see Hyperion5's post here.That assumes replacing the gas generator Merlin with a "mini Raptor" methane staged combustion engine that has equal thrust to Merlin. Replacing the current Merlin with an equivalent gas generator methane engine would probably give you a small decrease in performance, since methane's ~20% lower bulk density will have a slightly larger impact than the ~4% increase in ISP you get. There are some advantages to switching to methane, but you really need an entirely new high performance engine to make a big difference.
Quote from: spacenut on 04/16/2015 01:53 pmDo you guys think they will develop a methane Merlin? If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?They might, though if you're going to go "all-methalox", you generally want a big increase in performance to compensate for the rocket's increased dry mass and production costs. That's why I would suggest something like the following: Detailed figures on both Falcon 9-M & Falcon Heavy-M below: RocketFalcon 9-MFalcon Heavy-M (cross-feed)Payload to LEO24.93 mt78.16 mtGross Mass446 mt1262.99 mtDiameter3.66 m3.66 m x 3SI Gross Mass358.47 mt763.77 mtSI Propellant Mass 335.06 mt716.94 mtSI Engines9xMini-Raptor27xMini-RaptorSI SL Thrust576 tf1728 tfSI Vac Thrust651.4 tf1954.2 tfSI Engine Isp321/363321/363SII Gross Mass60.90 mt358.47 mtSII Propellant Mass56.80 mt335.06 mtSII SL ThrustN/A576 tfSII Vac Thrust70 tf651.4 tfSII Engine Isp380321/363SIII Gross MassN/A60.90 mtSIII Propellant MassN/A56.80 mtSIII Vac ThrustN/A70 tfSIII IspN/A380PLF Mass1.70 mt1.70 mtPLF separation time (sec.)220220
Do you guys think they will develop a methane Merlin? If so, what performance increase to GTO would that bring to Falcon Heavy with a properly sized upper stage, (stretched if need be)?
Quote from: Roy_H on 05/11/2015 04:38 amQuote from: baldusi on 05/11/2015 01:52 amPlease review this pictures of the Angara-3 cross-feed preliminary design.Well I disagree with your comments about shortcomings with my design, I am glad you posted the Angara pictures. Without understanding Russian, it is clear that tank-to-tank cross flow is viable (which I didn't think it was). Clearly by pressurizing the outboard booster tanks and not the central ones, sufficient fuel will flow from the outboard tanks to the central ones to power the central engine. The diagram shows the central tanks remaining completely full.Instead of a spool 3-way valve, you should use two on/off valves (one for in-core tank, one for booster incoming flow), a one way valve after the booster incoming flow valve to close the circuit after separation. And another one-way valve before the in core flow valve to avoid back flow. And somehow design the piping in such a way that it leaves no bubbles (or ad a heavy gas trap). Also, you should make sure that the process of opening one valve and close the other can comply with two requirements: no head pressure drop below the minimum engine specified AND generates no turbulence that may end up in cavitation.I don't know what's your experience with cryo liquids, but it's not that easy (but totally doable). Just not possible with a 3-way valve (which are specially heavy for big diameter piping.
In this video from the Planetary Society ...Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?
Quote from: Graham on 05/13/2015 08:21 pmIn this video from the Planetary Society ...Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?FWIW, references to FH start at about the 3:30 mark, and include CG video. More details on the mission are at the kickstarter page:https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraftwhich mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.One presumes that these are secondary payloads; nothing here says much specific about the primary, though.
Quote from: rst on 05/13/2015 09:21 pmQuote from: Graham on 05/13/2015 08:21 pmIn this video from the Planetary Society ...Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?FWIW, references to FH start at about the 3:30 mark, and include CG video. More details on the mission are at the kickstarter page:https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraftwhich mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.One presumes that these are secondary payloads; nothing here says much specific about the primary, though.During the Light Sail reveal event last year it was stated that PROX- 1 would be a secondary payload. I was under the impression that SpaceX was still aiming to fly the demo mission by the end of 2015, but Mr. Nye states that Light Sail will fly on the first flight of the FH in 2016. I'm just wondering if anyone here has heard if the demo mission has shifted to the right or if Mr. Nye mispoke.
Quote from: Graham on 05/13/2015 11:07 pmQuote from: rst on 05/13/2015 09:21 pmQuote from: Graham on 05/13/2015 08:21 pmIn this video from the Planetary Society ...Bill Nye and others are discussing the launch of Light Sail on the Falcon Heavy, Bill Nye states that it will be the first flight of the FH. Does TPS know something we don't, given that they are customers (i.e. the first flight is now 2016) or is Mr. Nye mistaken?FWIW, references to FH start at about the 3:30 mark, and include CG video. More details on the mission are at the kickstarter page:https://www.kickstarter.com/projects/theplanetarysociety/lightsail-a-revolutionary-solar-sailing-spacecraftwhich mentions that the sail will be carried by yet another experimental spacecraft (PROX-1 from Georgia Tech); all are pretty specific about FH being the launch vehicle.One presumes that these are secondary payloads; nothing here says much specific about the primary, though.During the Light Sail reveal event last year it was stated that PROX- 1 would be a secondary payload. I was under the impression that SpaceX was still aiming to fly the demo mission by the end of 2015, but Mr. Nye states that Light Sail will fly on the first flight of the FH in 2016. I'm just wondering if anyone here has heard if the demo mission has shifted to the right or if Mr. Nye mispoke.He didn't misspeak, he just left out "operational" (as stated in the Kickstarter campaign description and likely elsewhere).
Love Bill Nye, but I don't hang on every word he says when it's about something very technical.
The recent F9H video showed black legs and leg nacelles...Is this extra thermal protection than we have had to date?Does anyone know when we might see this leg configuration for the first time? Perhaps on a "regular" F9 launch soon?Thanks,Paul.
Quote from: paulcpaulc on 05/31/2015 10:21 pmThe recent F9H video showed black legs and leg nacelles...Is this extra thermal protection than we have had to date?Does anyone know when we might see this leg configuration for the first time? Perhaps on a "regular" F9 launch soon?Thanks,Paul.I always assumed that SpaceX intentionally used this "irregular" coloring scheme to easily differentiate between actual pictures and renderings/models. Though I like cscott's notion that it might represent composites, too.