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Rocket Design Agency - A Playtesting Quest

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Cast and Characters
  • Informational
    • NASA
    Brad L. Whipple - Director, New Alleghany Space Administration

    Payload Design - +1
    Rocket Design - +2
    Engine Design - +3
    Mission Planning - +1
    Flight Control - +2
    Damage Control - +0
    Spacecraft Activity - +0
    Extravehicular Activity - +0
    Experimental Activity - +2

    Flight Objectives
    - Continue scientific launches, progressing to probes into the space beyond orbit by year end 1959.
    - Begin experiments which will allow a progression to human spaceflight before year end 1960.
    - Cooperate with the Armed Forces in developing their abilities through the application of spaceflight.

    Mission Schedule - Current Date: January 1960
    - Low Orbit 1 (Summer 1958) - Hope-2 (Partial failure)
    - Re-entry test 1 - Sub-orbital - Full Success, August 1958
    - Low Orbit 2 - Partial Failure, Hope-3 , October 1958
    - Re-entry test 2 - Failure, November 1958
    - Military Communications - Success, ARTS, December 1958
    - High Orbit 1 - Success, Hope-4, January 1959
    - Re-entry test 3 - Success, March 1959
    - Bio-sciences - Launch Failure, July 1959
    - Discovery 1, Success, September 1959
    - High Orbit 2 - Success, Hope-5, October 1959
    - Lunar Probe - Launch Failure, Artemis-Lunar, November 1959
    - Bio-sciences - Success, Astrocaphe-Chuck, December 1959
    - Discovery 2 - Failure, January 1960
    - Astrocathe test - Success, animal in space, February 1960
    - March lost due to Artemis redesign
    - NAN payload - April 1960 - First Hermes Flight
    - Crown 3 - Spring/Summer 1960
    - Commercial payload - Summer 1960
    - IRVOS 1 - Summer 1960
    - NAA Communications - Summer/Fall 1960
    - Space Camp test - Summer/Fall 1960
    - NAN payload - Fall/Winter 1960
    - Commercial payload -Winter 1960
    - Astrocathe test - Winter 1960
    - NAA Communications - Spring 1961

    - Astrocaphe phase 1 (3 crewed flights)
    - Astrocaphe phase 2 (3 crewed flights)

    Hardware
    - Prometheus (1M to LEO)
    - Hermes-L (6M to LEO)
    - Hermes-B (8M to LEO)

    Andre Larkin - Team Lead at EPL
    Rocket Design 0
    Engine Design +2


    EPL Design Team
    Antony Miratha, Aerodynamics
    Susan Stone, Astrophysics
    Michael Cole, Rocket Engineering
    Amy Mathews, Trajectory Planning
    Simon T. Harrison, Chemical Engineering

    +2 Rocket Design, +2 Payload Design +1 Engine Design, +1 Fuel Selection, +1 Flight Planning

    Side Characters
    Dr. Evan Hart - Research Director at EPL
    Arthur Ley, proponent of Lunar flight.
    Franz Haber, Doctor and researcher.
    Dieter von Markand, Pacifist and astrophysicist.

    EPL Facilities
    Design workshop
    Chemical research laboratory
    Launch analysis equipment
    (Please note that EPL has neither rocket nor engine manufacturing facilities)
     
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  • Informational
    • Rolling NA.

    E: Beginning to think I've lost the favor of the dice gods.

    Either that, or someone altered the dice roller.
    Shadows threw 6 10-faced dice. Reason: Spoilers Total: 28
    1 1 5 5 1 1 10 10 8 8 3 3
    Shadows threw 2 10-faced dice. Reason: The Real Roll Total: 7
    1 1 6 6
     
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    My apologies. Haven't gotten around to taking another look at this. I'm at a convention this weekend, so that's been a bit of a distraction. As I said earlier, I've got something, but it ended up comparing quite unfavorably to some historical ones of similar payload, so I'd like to figure out what is going wrong and how to fix it.
     
    brmj said:
    My apologies. Haven't gotten around to taking another look at this. I'm at a convention this weekend, so that's been a bit of a distraction. As I said earlier, I've got something, but it ended up comparing quite unfavorably to some historical ones of similar payload, so I'd like to figure out what is going wrong and how to fix it.
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    It's no worries. I've got to get off my arse and actually design the other three :p
     
    Next time can please please try not to start a global nuclear war? Especially not in a world that hasn't fully grasped how nukes make unrestricted warfare a likely mass extinction event.
     
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    [x] Mccall Corrosive
    [x] Unkown 14 ton
    [x] BRMJ's design

    -Who's BRMJ? What does that even stand for?
    -Apparently "Big Rockets are My Job".
    -Well... That's we want isn't it?
     
    Okay, going to call this good enough rather than messing with it any more for the moment.

    The rocket I am building is designed to be as safe as is reasonably possible, since I for one am entirely tired of launch failures and there is no way this doesn't turn into a manned launcher at some point. In the case of the first stage, where most of the really serious risk usually seems to be and where the rocket equation is at its least tyrannical, going for robust, dead-simple, heavy and cheap design choices is a good way to do this. This adds cost because of how much bigger it gets, but fortunately those exact same design choices are the ones you'd realistically want for something that can survive an uncontrolled splashdown in the ocean without much damage. The end result should be a very low cost per launch if each first stage is reused enough, and coming out ahead relative to something more conventional so long as they are used maybe 3 times each on average. Exactly how cheap it can get is up in the air since I don't know the refurbishment and recovery costs or how many uses we can expect out of each stage, but it I would be shocked if these rules support an expendable rocket that would be competitive with the numbers we end up seeing in practice.

    @4WheelSword, before I go to the trouble of copying all this info over, I need a ruling.

    Do we have access to early refurbishment?

    Edit: other question removed; turns out it matters less than I had thought. Also, have some clarifications on the situation to help make my case. This is talking about a first stage with pressure fed hypergolic engines and a heavy duty tank, and it is only boosting things high enough to get past enough of the atmosphere for vacuum engines to work. The forces on it should be about as low as you could ask for, it is overbuilt relative to most rockets, and the engines are as simple and robust as you can get.
     
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    4WheelSword said:
    Yes you have access to early refurb
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    Wonderful.

    Oh, by the way, I think I've figured out why the rockets I was getting were turning out too large. The trust to weight ratio of the engines this system produces are wrong, at least for large engines. For example, a Rocketdyne F-1 ought to be around 33.6M and produce 6,770 kN at sea level. Trying to build one in this system, an engine of that mass produces only 2,564 KN at sea level. So, if my design's first stage engines are absurdly big, this (plus being pressure fed) is why.
     
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    brmj said:
    Wonderful.

    Oh, by the way, I think I've figured out why the rockets I was getting were turning out too large. The trust to weight ratio of the engines this system produces are wrong, at least for large engines. For example, a Rocketdyne F-1 out to be around 33.6M and produce 6,770 kN at sea level. Trying to build one in this system, an engine of that mass produces only 2,564 KN at sea level. So, if my design's first stage engines are absurdly big, this (plus being pressure fed) is why.
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    Hmm... That's frustrating. I wonder if there's a way to introduce size efficiency into the system.
     
    4WheelSword said:
    Hmm... That's frustrating. I wonder if there's a way to introduce size efficiency into the system.
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    Shouldn't be too hard, I would think, but doing it right will probably involve some number crunching. Fitting a line to the mass and thrust of otherwise comparable engines, probably. If that isn't enough alone to get better numbers out of it, it might be worth looking at modeling chamber pressure and different qualities of metallurgy.

    For the moment, I can either go with what I have or apply an ad-hoc correction based on the ratios with my fake F-1.
     
    Not a fan of corrosive fuels now that they have a significant reliability penalty.
    [X] O'Connel SRB
    [X] Unkown 14 ton
    [X] BRMJ's design
     
    brmj said:
    Shouldn't be too hard, I would think, but doing it right will probably involve some number crunching. Fitting a line to the mass and thrust of otherwise comparable engines, probably. If that isn't enough alone to get better numbers out of it, it might be worth looking at modeling chamber pressure and different qualities of metallurgy.

    For the moment, I can either go with what I have or apply an ad-hoc correction based on the ratios with my fake F-1.
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    Yeah I'll need to look at some sort of graph to think about how a multiplier should work.
     
    BRMJ LE-21A
    Fuel type: Aerozine/RFNA (toxic)
    Cycle: Pressure fed (21M, 3.15M mass flow, +1 safety)
    Injector: Centripetal
    Nozzle: Atmospheric (12.6M)
    Upgrades: Single Axis Vernier (+1 control)
    ISP: 288
    Thrust: 2453.79456kN
    Mass: 34.23
    Cost: 47.8815
    Though perhaps the largest and most powerful engine ever seriously proposed, the LE-23A is a simple and robust design, with hypergolic fuel for simple and reliable ignition and pressure fed operation for reliability. Some argue that the design is overbuilt to the point of absurdity, and that an engine of the same intended performance, even a pressure fed one, ought to be under half the size.

    BRMJ LE-17V
    Fuel type: RP-1/LOX
    Cycle: Gas generator (1.7M, .51M mass flow)
    Injector: Centripetal
    Nozzle: Vacuum (2.04M)
    Upgrades: Single Axis Vernier (+1 control)
    ISP: 364.6075
    Thrust: 419.1309056kN
    Mass: 3.842
    Cost: 5.8155
    BRMJ LE-18V
    Fuel type: RP-1/LOX
    Cycle: Gas generator (1.7M, .51M mass flow)
    Injector: Centripetal
    Nozzle: Vacuum (2.04M)
    Upgrades: Restartable, Multiple Axis Vernier (+1 control)
    ISP: 364.6075
    Thrust: 419.1309056kN
    Mass: 3.9202
    Cost: 6.2555
    The LE-17V is a fairly standard modern RP-1 engine with a vacuum nozzle and a pair of vernier engines, designed to be mounted in small clusters in a second stage. The LE-18V is a derivative with restart capability and a full set of verniers intended for use alone as an upper stage engine.

    BRMJ Partially reusable launch vehicle proposal
    Payload - 40 Mass (10 tons)
    Stage 3 Mass - 112.6432 Mass (28.16 tons)
    Stage 2 Mass - 1000.00743 Mass (250 tons)
    Stage 1 Mass - 1763.440219 Mass (440.860 tons)
    Total Mass - 2876.090854 Mass (719 tons)
    Stage 3 Cost- 7.7688 Cost
    Stage 2 Cost - 53.1551 Cost
    Stage 1 Cost - 814.5596 Cost
    Total Cost- 875.4835 initial, 60.9239 + refurb for each additional launch
    Stage 3 Thrust - 419kN
    Stage 2 Thrust - 2934kN
    Stage 1 Thrust - 14723kN
    Stage 1 Delta-V - 1526.2m/s
    Stage 2 Delta-V - 5423.4m/s
    Stage 3 Delta-V - 3803.9m/s
    Total Delta-V - At least 10753m/s (Over 1000 after DMR penalty)

    Stage 1 Design
    Engine - 6 x LE-21A, ISP: 288 (205.38M/287.289C, +1 safety, +1 control)
    Stage - 127M (2.54C) Heavy Duty, 1270M fuel (+1 safety)
    Avionics: Basic gyroscopic guidance (+2 control)
    Control: Small fins (+1 stability)
    Suborbital heat-shield
    Parachute
    Separator: Explosive Bolt
    Launch TMR >2 (+1 stability)
    DMR 1.5/1 (+1 stability)
    Totals: +2 safety, +3 control, +3 stability

    Stage 2 Design
    Engine - 7 x LE-17V, ISP: 364.6075 (26.894M/40.7085C, +1 control)
    Stage - 45M (4.5C) Structural Steel, 900M fuel
    Avionics: Basic gyroscopic guidance (+2 control)
    Separator: Explosive Bolt

    Stage 3 Design
    Engine - 1 x LE-18V, ISP: 364.6075 (3.9202M/6.2555C, +1 control)
    Stage - 5M (.5C) Structural Steel, 100M fuel
    Avionics: Basic gyroscopic guidance (+2 control)
    Separator: Explosive Bolt
    The second and third stages are fairly conventional in design, aside from their size and the choice to use derivatives of the same engine for both to reduce development and manufacturing costs. RP-1 was selected primarily to maximize ISP. The first stage, however, is a little weirder. Six enormous pressure fed hypergolic engines propel it, while the tank is of unusually heavy but simple, robust and cheap construction, and reinforced to withstand the forces it will experience during reentry and landing. After stage separation, the first stage is intended to continue through its ballistic flight, deploy parachutes during descent and splash down uncontrolled. Following landing, residual pressurant is used to purge excess seawater from the engines, and the stage may be recovered either with a crane ship or by ballasting it to float horizontally and and towing it to shore for refurbishment. It is difficult to convincingly estimate refurbishment costs at this stage, but even with a fairly conservative estimate of 25% of the cost of a new stage, it should be cost effective relative to a similar non-reusable stage starting on the third flight and promises very substantial eventual savings.

    Though the current design is not well suited to stage-stretching and the like, new, larger, perhaps hydrogen fueled second and third stages could likely add considerable launch capacity in the future. As it stands, this design is capable of putting 15.65 mass into geosynchronous transfer orbit, and should be capable of sending very useful payloads on interplanetary trajectories.

    Spreadsheet

    Edit: One other note. A non-explosive engine failure in the first stage should be survivable by the simple expedient of shutting down the opposite engine to match. Likewise on the second stage, once it has burnt enough fuel for a TWR of greater than 1 on 5 engines. The game doesn't currently model this, but it is neat and is the sort of thing that can be useful for safety.
     
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    brmj said:
    Edit: One other note. A non-explosive engine failure in the first stage should be survivable by the simple expedient of shutting down the opposite engine to match. Likewise on the second stage, once it has burnt enough fuel for a TWR of greater than 1 on 5 engines. The game doesn't currently model this, but it is neat and is the sort of thing that can be useful for safety.
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    Heck, the second stage could survive a center engine failure even more easily - because it's a center engine, shutting it down ahead of the others doesn't necessitate shutting down an opposing engine to avoid loss of balance.
     
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