Author Topic: Blue Moon Lunar Lander  (Read 5212 times)

Offline sanman

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Re: Blue Moon Lunar Lander
« Reply #20 on: 03/10/2017 04:24 AM »
I was just wondering why methalox in particular for those landing thrusters. You guys have said it's the easiest cryoprop, and that it may be a spinoff of BE-4.

What about LH2-Fluorine? It's got superior Isp, and the Moon has no ozone layer or atmosphere to contaminate, and the mass savings it provides could be significant when lugging it all the way to the Moon.

A 1-way lander that isn't reused wouldn't have to worry so much about the higher reactivity of fluorine posing greater corrosion risk over time.

Offline Steven Pietrobon

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Re: Blue Moon Lunar Lander
« Reply #21 on: 03/10/2017 06:01 AM »
What about LH2-Fluorine? It's got superior Isp, and the Moon has no ozone layer or atmosphere to contaminate, and the mass savings it provides could be significant when lugging it all the way to the Moon.

Unfortunately, LF2 is extremely toxic and corrosive. It would be a nightmare if something went wrong on the ground. Being cryogenic, you'd need to take extreme care with the boil-off. Its so powerful, that it will burn with water, with an Isp similar to that of solid motors!

Propellants  MR   dp (kg/L)  ve (m/s) Id (Ns/L)
F2/H2       14.6   0.6553     4704     3083
F2/H2O       2.1   1.2942     2876     3722
F2/HTP       0.88  1.4689     2966     4357
F2/NH3       3.4   1.1770     4115     4843
F2/B2H6      6.4   1.1314     4416     4996
F2/N2H4      2.3   1.3073     4212     5506
« Last Edit: 03/10/2017 06:07 AM by Steven Pietrobon »
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Offline sanman

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Re: Blue Moon Lunar Lander
« Reply #22 on: 03/10/2017 12:42 PM »
Yeah, I know Fluorine is famously toxic, but would that matter so much on the Moon? Okay, you wouldn't want any mishaps on Earth, but in the lunar environment the toxicity wouldn't be terribly relevant. Meanwhile there's a fair amount of Fluorine in some of the lunar rocks:


http://www.sciencedirect.com/science/article/pii/S0016703711003450

Offline savuporo

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Re: Blue Moon Lunar Lander
« Reply #23 on: 03/10/2017 12:59 PM »
Yeah, I know Fluorine is famously toxic, but would that matter so much on the Moon?..
It's not about the target operational environment. The problem is that someone would have to spend a good decade doing development with it, and then shift to operations with fueling and spacecraft integration issues etc.

There is a good reason why a reasonable part of industry is searching for other alternatives to hydrazine as well. Going fluorine would be a step backwards, not forward.
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Online brickmack

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Re: Blue Moon Lunar Lander
« Reply #24 on: 03/10/2017 03:08 PM »
Because going pump fed from no deep space flight heritage is simply infeasible, considering it hasn't been done before.
State of the art of deep space main engines is still hypergolic, pressure fed.

Theres no such thing as a "deep space main engine", the statement is meaningless. Any engine becomes a deep space main engine once you take it to deep space and use it. The only functional difference between this application and a standard upper stage is time on-orbit, and theres plenty of examples of pump fed engines lasting far longer in space than is necessary for this

Online Robotbeat

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Re: Blue Moon Lunar Lander
« Reply #25 on: 03/11/2017 04:19 AM »
What propulsion will it use?
Not a pump-fed engine. Or an electric pump, perhaps.
And why NOT pump-fed? Smaller pumpfed engines have been developed. The Fregat stage is pumpfed but half the thrust. Do you have any evidence that it's not pump-fed? If it's just your opinion, say so. Don't state it as if it's a fact.

Because going pump fed from no deep space flight heritage is simply infeasible, considering it hasn't been done before.
State of the art of deep space main engines is still hypergolic, pressure fed.
Fregat, which is the small pump-fed example I used, is as deep space as anything. I believe it can last for days in orbit in between burns, which is enough to go all the way to the Moon.

Blue Origin hasn't even done anything orbital yet, but that doesn't seem to be stopping their ambitions, so don't let that count as evidence it wouldn't be pumpfed.
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Online Kryten

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Re: Blue Moon Lunar Lander
« Reply #26 on: 03/11/2017 09:21 AM »
Fregat, which is the small pump-fed example I used, is as deep space as anything. I believe it can last for days in orbit in between burns, which is enough to go all the way to the Moon.
Fregat's ancestor, the Phobos probes' ADU propulsion unit, used the same engine for Mars orbit insertion after a six month cruise.

Offline Dante80

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Re: Blue Moon Lunar Lander
« Reply #27 on: 03/13/2017 01:49 AM »
I don't think that the lander will utilize BE-3. Bezos never said that explicitly (he talked about the system using the BE-3U, not the lander itself), and he also talked about the lander having multiple descent engines.

BE-2 comes to mind. I might be wrong on this of course.

Edit: Saw the quote above about methalox thrusters. My bad.
« Last Edit: 03/13/2017 08:09 AM by Dante80 »

Offline Norm38

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Re: Blue Moon Lunar Lander
« Reply #28 on: 03/13/2017 01:49 PM »
But of course more recent experience with vertical rocket landings on Earth (F9, New Shepard) suggest a different approach might be possible on the Moon as well, i.le. don't bother with hovering, just hoverslam onto the surface.

Hoverslam landings  are probably fine once a base is operational and a nice big landing field has been cleared.  But for early missions, how much imaging resolution will they have before hand to know they're not coming down on top of a big boulder, or other terrain they can't land on?  They may need to be able to hover and translate. 

Offline savuporo

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Re: Blue Moon Lunar Lander
« Reply #29 on: 03/13/2017 03:26 PM »
Because going pump fed from no deep space flight heritage is simply infeasible, considering it hasn't been done before.
State of the art of deep space main engines is still hypergolic, pressure fed.

Theres no such thing as a "deep space main engine", the statement is meaningless. ..
Yes  there is.

BT-4, Leros variants, AJ10 derivatives and so on. Common characteristics are low complexity, high redundancy, extensive flight heritage.

Indeed it appears KTDU-425A/KRD-425A/11D425A flew to Mars and fired - i wasn't aware at all. And according to sources, some predecessors from the S5 engine series, 11D417/KRD-417 flown on Luna 15-24 were already pump-fed as well. ( I'm now really interested in obtaining a copy of Bolonkin A. A. The Development of Soviet Rocket Engines, Delphic Ass., 1991, 134 p. ISBN 1-55831-130-0 that would probably be the authoritative source documenting the evolution of it )

Note that this engine series underwent extensive development iterations and multiple spaceflights before it became part of Ye-8-5, Ye-8-5M, ADU and eventually Fregat.

Fregat has also had a spectacular series of malfunctions, but more often than not they have been control systems related than engine/plumbing.

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Offline sdsds

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Re: Blue Moon Lunar Lander
« Reply #30 on: 03/14/2017 07:36 AM »
how much imaging resolution will they have before hand to know they're not coming down on top of a big boulder, or other terrain they can't land on?

Maybe they could locate a landing site with synthetic aperture radar?

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a miniSAR-equipped aircraft flying within 10 kilometers over a golf course "could resolve the fact that there were two golf balls 4 inches apart"
http://www.aviationtoday.com/2006/09/01/product-focus-sar-antennas-increased-abilities-smaller-size/
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Offline sanman

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Re: Blue Moon Lunar Lander
« Reply #31 on: 03/15/2017 05:38 PM »
Or maybe even just LIDAR?

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