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Suborbital Missions / Re: The suborbital thread!
« Last post by Steven Pietrobon on Today at 04:10 AM »
Poland's Centre of Space Technologies of Institute of Aviation launched a hybrid sounding rocket on 22 October 2017 called ILR-33 Amber (Bursztyn). It used 98% HTP, the first rocket to use that high a concentration. Altitude was 15 km with a partial propellant load. With a full load, they claim they can get 100 km.

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NK-forum:
23 июня – Космос-2519 (14Ф150 "Напряжение" ), Космос-2521 (спутник инспектор), Космос-2523 (ПО) – Союз-2-1В/Волга – Плесецк 43/4 – 21:04:33

 (ПО) apparently analogous "TBD"

Russian friends can help ?
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SpaceX Mars / Re: Elon The Boring Company
« Last post by Robotbeat on Today at 04:00 AM »
Is there a better way?  I sure darn hope so!!!

Monorails!

But for whatever reason Musk is not interested in them, so we have tunnels instead - which could prove useful on Mars...

Whilst promising much, monorails have their problems also.  For a case study in point:

The Sydney Monorail system was installed in Sydney, Australia, following a brief stint shuttling folks around at Brisbane's Expo '88 and ran (at a government-funded loss) until 2013.  It seems that, being more expensive to operate, it's installation in preference to a light-rail system was mostly political and that in ~25 years of operation it was "never truly embraced by the community".

https://en.wikipedia.org/wiki/Sydney_Monorail

I'm sure that with proper planning, selection and a fair bit of compulsory acquisition, a Monorail system could be made to work, but there's no doubt constructing a tunnel system within the confines of a modern city is far less disruptive and far more politically digestible than a monorail.
I like Musk and all, but...
I can't help but think of this song when the Hyperloop comes up. (And I kind of think the Hyperloop would work.)
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w in 2025).
2) perform "solar fry-by" Oberth boost at distance current thermal technologies can handle:
         - calculated that "fry by" at 3 solar radii would give sufficient kick to achieve rendezvous by itself.
         - perhaps "fry by" is possible with current tech at 30 or 300 solar radii (how close can we go safely?).
3) Deploy solar sail technology to make up the difference in delta-V.*
In short - no.
To get any meaningful benefit for this mission, it needs to be very, very close to the sun.

*Firstly I've added point 3 back into the quote.  Even a "lightsail" style (32m2) solar sail could add a decent dV to a New Horizon's sized probe.

But I guess I'm confused by your answer.  I've always understood the size of the Oberth effect to be proportional to the velocity of the spacecraft when the burn is made (at perihelion in this instance).  In order to get to the "fry-by"  transfer orbit in the first place you've given your spacecraft a Jupiter gravity assist, so the semi-major axis of that transfer orbit has to be about 2.6 AU.  Given this large semi-major axis, how big a difference does a perihelion distance is 0.014 AU (3 solar radii), versus 0.14 AU (30 solar radii), really make? especially when it can make such a difference to the mass/complexity of your shielding apparatus?

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My vote also goes for Boca Chica to launch the BFR it is proposed site
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Tweet from Matt Desch:
Quote
My schedule, provided by SpaceX shows it as 5:27:23 PST...
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SpaceX Mars / Re: Elon The Boring Company
« Last post by Lar on Today at 03:30 AM »
Having said that, I want to go back to flying bridges...

...

Relevance?  Well to show some of the underground complexity and simply tunneling is not perhaps the best solution, since there is so many things to build.

With mature cities like Los Angeles cut & fill is not an option.

As for comparisons of the tunnels The Boring Company is making vs subway tunnels, I think there will be a number of factors that make them different.

For instance subways are built for people to be moving around and about, where what Musk is building will only have automated skates. That will allow for small off-ramps and more efficiency.

Quote
Is there a better way?  I sure darn hope so!!!

Monorails!

But for whatever reason Musk is not interested in them, so we have tunnels instead - which could prove useful on Mars...

But the issue is, the complexity of interchanges required, once you go beyond a single tube, gets, well, complicated.  So this is a hard issue to deal with, In the past, cut and cover was used, and obviously will not be an option.  So how does the Boring Company plan to deal with that?

Discuss...  Like butter.

But again, point is in bringing up the hard issues to discuss.

As for simpler ramps, this is less about on/off ramps as it is aboout interchanges.  There will be interchanges, that is a certainty.  Or maybe their innovation will be direct paths to everything, since tunnelling will become so cheap.  Who knows?

TBC’s plan so far has a lot of secondary tunnels and forks since that’s how access works. It’s implied that there will be interchanges. For this to be handled without cut and fill with no surface disruption it would certainly be helpful if a TBM could travel forwards and backwards through a tunnel it made. This would allow tunnels to be forked at any point even after initial construction. It would allow easy recovery of any TBM since it could just return to its start point. It would make it much less likely TBMs would get stuck. It would allow TBMs to change cutting shields (or whatever you call those) which would be useful if the geology changes. It would allow any part of the TBM to be replaced extending their useful life.

Now that we hit on it, it sure seems like an obvious enhancement that saves a lot once implemented...
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SpaceX Mars / Re: Elon The Boring Company
« Last post by Ludus on Today at 03:19 AM »
Having said that, I want to go back to flying bridges...

...

Relevance?  Well to show some of the underground complexity and simply tunneling is not perhaps the best solution, since there is so many things to build.

With mature cities like Los Angeles cut & fill is not an option.

As for comparisons of the tunnels The Boring Company is making vs subway tunnels, I think there will be a number of factors that make them different.

For instance subways are built for people to be moving around and about, where what Musk is building will only have automated skates. That will allow for small off-ramps and more efficiency.

Quote
Is there a better way?  I sure darn hope so!!!

Monorails!

But for whatever reason Musk is not interested in them, so we have tunnels instead - which could prove useful on Mars...

But the issue is, the complexity of interchanges required, once you go beyond a single tube, gets, well, complicated.  So this is a hard issue to deal with, In the past, cut and cover was used, and obviously will not be an option.  So how does the Boring Company plan to deal with that?

Discuss...  Like butter.

But again, point is in bringing up the hard issues to discuss.

As for simpler ramps, this is less about on/off ramps as it is aboout interchanges.  There will be interchanges, that is a certainty.  Or maybe their innovation will be direct paths to everything, since tunnelling will become so cheap.  Who knows?

TBC’s plan so far has a lot of secondary tunnels and forks since that’s how access works. It’s implied that there will be interchanges. For this to be handled without cut and fill with no surface disruption it would certainly be helpful if a TBM could travel forwards and backwards through a tunnel it made. This would allow tunnels to be forked at any point even after initial construction. It would allow easy recovery of any TBM since it could just return to its start point. It would make it much less likely TBMs would get stuck. It would allow TBMs to change cutting shields (or whatever you call those) which would be useful if the geology changes. It would allow any part of the TBM to be replaced extending their useful life.
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Based on this engine, I assume Landspace is developing a 90 ton reusable rocket just like mini-Falcon 9
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Landspace has successfully conducted first preburner testing of its 10 ton methane engine named Fenghuang(Phoenix)
http://mp.weixin.qq.com/s/8lwwLOZE12yuZ0-Xjt8dTg
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