Author Topic: Starship Single Stage Earth Point to Point  (Read 94889 times)

Offline cdebuhr

  • Full Member
  • ****
  • Posts: 834
  • Calgary, AB
  • Liked: 1408
  • Likes Given: 588
Re: Starship Single Stage Earth Point to Point
« Reply #240 on: 10/09/2020 10:57 pm »
It's not just a matter of Starship not being appropriate for contested airspace -- it also has huge logistical requirements. I very much doubt that it can effectively and safely land without a pad, as the plume would spray rock and sand everywhere, potentially damaging both itself and any equipment and personnel nearby. And once it is landed, how does it take off again? It needs liquid oxygen, liquid methane, and specialized ground support equipment.

To me it makes no more sense to think that a Starship would land in austere combat conditions than it would to expect a C-17 to land in a field. It may make sense for very time-sensitive cargo to remote prepared bases, but even those bases would have to have specialized gear to ensure the trip is not one-way.
While I agree for most of the reasons discussed that combat landings into a hot LZ are likely far-fetched at best.  I do have a couple quibbles with  this.  First is that Starship has, as a base requirement, the ability to land on unprepared surfaces.  Musk never mentions sending a swarm of small, robotic LZ-prep-bots to Mars.  Second quibble is with respect to taking off again.  We're talking about the military here, not commercial point-to-point.  If this thing can get anywhere near the per-unit price-points that Musk has discussed in the past, it's completely plausible that the these could be dispatched on one-way missions.

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 6301
  • Michigan
  • Liked: 4182
  • Likes Given: 2
Re: Starship Single Stage Earth Point to Point
« Reply #241 on: 10/09/2020 11:02 pm »
Test next year, 80 tonnes of cargo.

https://www.c4isrnet.com/space/2020/10/07/the-pentagon-wants-spacex-delivering-cargo-around-the-globe-and-a-live-test-could-come-next-year/

Quote
Pentagon wants SpaceX delivering cargo around the globe — and a live test could come next year

WASHINGTON — U.S. Transportation Command is taking the potential for cargo delivery via orbit seriously enough that it hopes to test the concept with SpaceX as soon as next year, the command’s head said Wednesday.
>
The dream, Lyons told the National Defense Transportation Association, is to be able to move 80 tons of cargo - the equivalent of a C-17 transport - via a space-based vehicle anywhere on the globe within one hour.
>
« Last Edit: 10/09/2020 11:03 pm by docmordrid »
DM

Offline cwr

Re: Starship Single Stage Earth Point to Point
« Reply #242 on: 10/10/2020 05:29 am »
I'd also add that, based on my experience overseas, the issue is less MANPADs being fired on descent, and more likely cheap disposable mortars aimed in the general vicinity of the tankfarm, from outside the base and on a timer so the attacker can get away.

I'd guess that returning the Starships is on the DoD's list of nice-to-have features, but I'm pretty sure that they'd be perfectly happy with expendables--just as long as they landed and discharged their payload before they were expended.

Having 1200t of LCH4 next to your ammo dump has to be the stuff of quartermasters' night terrors.
I have no expertise in this area, but it occurs to me that there are a number of possibilities
for mission design:
a) One scenario could be a SH boosts a SS with palletized loads plus parachutes for the pallets.
    SH does an RTLS after staging.
    Once the SS has entered atmosphere to heights akin to C-17 drop heights and the pallets
    are ejected then the SS reignites its engines to reach the nearest safe  landing site.
    There are some payloads that might need a crew to operate and this might mean
   a crew capsule to be ejected as well as the delivered H/W.
b) Another scenario could involve targeting a SS at a prepared landing site [landing pad, crane for unloading
    pallets (perhaps comes with the SS as we've seen in some renders) and fuel for SS return].
    Then the pallets have to be transported to the required location. After delivery the SS needs to be
    refueled so it can fly back to it's home base - possibly in multiple hops if a SH was used to boost
    the SS originally.

It seems there are multiple facets to the mission:
1) Where the vehicle is launched from - presumably the USA or a forward logistics base.
2) If boosted by SH then presumably RTLS would be required.
3) How is delivery targeted eg pallets parachuted to target or SS lands closer to target at prepared
    landing site with necessary items to deliver payload to the required site and to allow the SS
    to return to home base by one or more hops.
4) SS returns to home base.

There are other variants but this seems to cover a lot of possibiliies.

Just speculating

Carl
« Last Edit: 10/10/2020 05:38 am by cwr »

Online catdlr

  • Member
  • Senior Member
  • *****
  • Posts: 6737
  • Enthusiast since the Redstones
  • Marina del Rey, California, USA
  • Liked: 3348
  • Likes Given: 2676
Re: Starship Single Stage Earth Point to Point
« Reply #243 on: 10/10/2020 07:35 am »
The US military and Elon Musk are planning a 7,500-mph rocket that can deliver weapons anywhere in the world in an hour

Source:

Quote
The US military is teaming up with Elon Musk's SpaceX to build a rocket capable of delivering weapons around the world at 7,500 mph.
The plans call for a rocket that can carry 80 metric tons of cargo into space and land anywhere in the world in about an hour.
SpaceX will now assess the costs and technical challenges of the project, while initial tests are expected in 2021.


Tony De La Rosa

Offline DreamyPickle

  • Full Member
  • ****
  • Posts: 912
  • Home
  • Liked: 879
  • Likes Given: 196
Re: Starship Single Stage Earth Point to Point
« Reply #244 on: 10/10/2020 08:18 am »
There has been a lot of speculation around this but I'm still surprised the military is actually interested.

There are severe limitations because if you want the rocket to come back you need a launch mount and Super Heavy and thousands of tons of methane at every location, and you need to clear a few KM around the pad for every flight.

Is this really worth the reduced flight time for cargo?

Offline Star One

  • Senior Member
  • *****
  • Posts: 13084
  • UK
  • Liked: 3537
  • Likes Given: 220
Re: Starship Single Stage Earth Point to Point
« Reply #245 on: 10/10/2020 09:28 am »
I believe this is the original article unfortunately most of it is behind a paywall.

https://www.flightglobal.com/defence/pentagon-spacex-may-demo-rocket-delivery-of-cargo-in-2021/140514.article

Online Cheapchips

  • Full Member
  • ****
  • Posts: 955
  • UK
  • Liked: 758
  • Likes Given: 1670
Re: Starship Single Stage Earth Point to Point
« Reply #246 on: 10/10/2020 09:51 am »
There has been a lot of speculation around this but I'm still surprised the military is actually interested.

There are severe limitations because if you want the rocket to come back you need a launch mount and Super Heavy and thousands of tons of methane at every location, and you need to clear a few KM around the pad for every flight.

Is this really worth the reduced flight time for cargo?

Speed of delivery clearly is important to them.  Army's march on their stomachs and all that.   :)

"Around the world" can really be taken as bases around the world.  These will already have a significant secure perimeter and fuel logistics. They don't need SH for the return leg. A Starship with no cargo can make its own way back. This reduces the infrastructure significantly.  You only need a few hundred of tons of methane. LOX has various options.

Long term, SS isn't the only way to get things down to the ground. They could use more disposable reentry methods for emergency logistic to hotter conflict zones.

Offline aero

  • Senior Member
  • *****
  • Posts: 3614
  • 92129
  • Liked: 1135
  • Likes Given: 358
Re: Starship Single Stage Earth Point to Point
« Reply #247 on: 10/10/2020 02:17 pm »
Quote
So it's either going to be considered expendable or it's going to land at a prepared LZ with some plan for later refueling.

In some situations their may be a prepared landing field within reachable range of the remaining prop, especially after point-to-point becomes a thing. The mission might require some trajectory shaping to take advantage but they won't want to expend a Starship. Its not the $cost so much as it is mission capability. You can't fly a mission next week with a Starship that you expended last week!

I guess the build numbers have to be based on the utilization plan. Normal mission recovery - build a number, expendable mission expectation - build and inventory a large number of Starships.
Retired, working interesting problems

Offline CuddlyRocket

Re: Starship Single Stage Earth Point to Point
« Reply #248 on: 10/10/2020 04:03 pm »
There are severe limitations because if you want the rocket to come back you need a launch mount and Super Heavy and thousands of tons of methane at every location, and you need to clear a few KM around the pad for every flight.

Is this really worth the reduced flight time for cargo?

Elon has said that Starship when operating on point-to-point mode on Earth does not need the super-heavy 'which simplifies things tremendously'. It does not need a launch mount as it is designed to launch from unprepared surfaces, such as on Mars or the Moon. How much propellant it needs to reserve for the return trip, empty, is unclear. It depends on how far the return trip is - is it going back to its departure point or just somewhere else closer that's safe? Whether it has enough propellant depends on how much cargo it's taking and how far. They're talking about a 7,500 mile here whereas SpaceX is talking about a 10,000 mile range, so there's obviously somethhing in reserve.

If it's a military operation they don't need to clear a few km. It's nice, but if push come to shove the military tends to do what it needs to do. As for whether this is all worth the reduced flight time etc, then that's for military planners to decide. They're very alive to the requirements of logistics, which are the prerequisite for successful military operations.

Edit: Sorry, misread 7,500 mph for 7,500 range! But the point still stands. If they're prepared to accept a shorter range, they may well be able to reserve propellant for a return trip.
« Last Edit: 10/10/2020 04:06 pm by CuddlyRocket »

Offline spacenut

  • Senior Member
  • *****
  • Posts: 4668
  • East Alabama
  • Liked: 2280
  • Likes Given: 2331
Re: Starship Single Stage Earth Point to Point
« Reply #249 on: 10/10/2020 04:54 pm »
My son did two tours in Afghanistan.  Both times he was stationed at an air base.  He said helped guard the perimeter.  He also said this air base took large planes like C-5's, helicopters, etc.  Anyway, the base was plenty large to quickly deliver supplies, fuel up and return.  Yes a base would have to be established first, usually in a nearby friendly country, like Kuwait before the Iraqi invasion.  Rockets would be faster to deliver goods than a large plane needing 12 or more hours of time to get there, especially when speed is needed. 

I have seen rocket ideas for delivery of troops and supplies going around for 60 years or more.  First one being Bono's Rombus large reusable rockets.  Once a base is established somewhere, fuel and lox can be manufactured at the base on a continuous basis so rockets can refuel and return. 

The 7,500 mile range also could use European bases to get stuff into a Middle Eastern hot spot or even Korea from Japanese bases quickly. 

Online niwax

  • Full Member
  • ****
  • Posts: 1290
  • Germany
    • SpaceX Booster List
  • Liked: 1823
  • Likes Given: 154
Re: Starship Single Stage Earth Point to Point
« Reply #250 on: 10/10/2020 06:47 pm »
Some interesting calculations using the spreadsheet from https://hopsblog-hop.blogspot.com/2014/06/travel-on-airless-worlds.html:

If we assume a Starship has 7500m/s and EDL takes 300m/s, there are 3450m/s available per leg. This is enough for just over 12°, or 1350km range. Total flight time: 2m:45s, not regarding slowdown due to the atmosphere.

With 8000m/s / 250m/s, for example because of less weight or one empty leg, this goes up to 14.5° / 1611km in 3m:09s.

It's not enough range to be practical for regular use, but there is a certain cyberpunk charm to ferrying stuff with a shiny silver rocket that can go there and back in under ten minutes.
Which booster has the most soot? SpaceX booster launch history! (discussion)

Offline aero

  • Senior Member
  • *****
  • Posts: 3614
  • 92129
  • Liked: 1135
  • Likes Given: 358
Re: Starship Single Stage Earth Point to Point
« Reply #251 on: 10/10/2020 10:41 pm »
Having 1200t of LCH4 next to your ammo dump has to be the stuff of quartermasters' night terrors.

Only ~250 tonnes of LCH4 per refill, but of course you might hold multiple re-fills in the tank farm...

If you liquified the CH4 on-demand from a pipeline, you wouldn't have to store LCH4 in the tank farm, instead storing LN2. Playing with the online pipeline calculator, it looks like a ~22 inch natural gas pipeline should supply enough flow rate to fill Starship in 30 minutes.

Well - I don't think that idea is economically feasible. Liquification plants are expensive and this idea assumes a plant sited at every potential trouble spot where use of Starship might be some day required. The cost of liquification is driven down by economies of scale, that is huge plants. The idea of a plant sized to fuel a Starship misses on economies of scale, though it would not be a small plant either, to process a tank load of LNG in 30 minutes.

Better to plan to leave the Starships and build new ones. The Raptors can be ferried out by aircraft and the tanks demolished where they sit.
Retired, working interesting problems

Offline Twark_Main

  • Senior Member
  • *****
  • Posts: 2301
  • Technically, we ALL live in space...
  • Liked: 1341
  • Likes Given: 885
Re: Starship Single Stage Earth Point to Point
« Reply #252 on: 10/10/2020 10:55 pm »
it would not be a small plant either, to process a tank load of LNG in 30 minutes.

AFAIK currently SpaceX sub-chills the LCH4 on-demand during prop loading, using a LCH4-to-LN2 heat exchanger. I presume they'd use a similar approach here.

Modest size air liquefaction plant provides a "slow drip" into LOX and LN2 tanks. I don't know what type of facility you were picturing, but I think this addresses (at least in part) your concerns about economic feasibility. Obviously the cost can't be zero, but the facility need only be sized for the expected flight rate + boiloff, not massively oversized in order to fuel a Starship every 30 minutes.

I find it surprising that you only need a modest diameter pipeline and you can completely eliminate the on-site LCH4 tanks.

Better to plan to leave the Starships and build new ones. The Raptors can be ferried out by aircraft and the tanks demolished where they sit.

Certainly this will always be the best option in certain cases. But the cheaper you can make the refueling hardware, the fewer situation you'll be forced to do this in.
« Last Edit: 10/10/2020 11:07 pm by Twark_Main »
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline aero

  • Senior Member
  • *****
  • Posts: 3614
  • 92129
  • Liked: 1135
  • Likes Given: 358
Re: Starship Single Stage Earth Point to Point
« Reply #253 on: 10/10/2020 11:08 pm »
it would not be a small plant either, to process a tank load of LNG in 30 minutes.

AFAIK currently SpaceX sub-chills the LCH4 on-demand during prop loading, using a LCH4-to-LN2 heat exchanger. I presume they'd use a similar approach here.

Modest size air liquefaction plant provides a "slow drip" into LOX and LN2 tanks. I don't know what type of facility you were picturing, but I think this addresses (at least in part) your concerns about economic feasibility. Obviously the cost can't be zero, but the facility need only be sized for the expected flight rate + boiloff, not massively oversized in order to fuel a Starship every 30 minutes.

I find it surprising that you only need a modest diameter pipeline and you can completely eliminate the on-site LCH4 tanks.

Note that the desired end product of liquification is not LNG but rather LCH4. The natural gas has to be cleaned/purified either before or after liquification. That or else the Raptors need to be certified to burn dirty fuel.
Retired, working interesting problems

Online oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 4923
  • Florida
  • Liked: 4391
  • Likes Given: 783
Re: Starship Single Stage Earth Point to Point
« Reply #254 on: 10/10/2020 11:20 pm »
it would not be a small plant either, to process a tank load of LNG in 30 minutes.

AFAIK currently SpaceX sub-chills the LCH4 on-demand during prop loading, using a LCH4-to-LN2 heat exchanger. I presume they'd use a similar approach here.

Modest size air liquefaction plant provides a "slow drip" into LOX and LN2 tanks. I find it surprising that you only need a modest size pipeline and you can completely eliminate the on-site LCH4 tanks.
With a sufficient source of CH4 (gas). You can use it to manufacture the LOX and LN2 prior to the manufacture step for LNG to then do a full prop load of an SS.

The basic question is just how much equipment is needed and if it is worthwhile vs just trucking in enough prop to then fly the SS far enough that it can get to a facility that has LOX and LNG. A quick estimate calculation such that an SS without payload and loaded with ~300mt of prop could go as far as several 100km.  So after a couple of days of flying in the prop on C-130's you get the SS back to a regular large source of LOX and LNG. There it would be fully fueled and the go back to a full service P2P platform. Most cases would not need delivery of infrastructure to the SS location but just enough prop ~6 C-130 flights over a couple of days to get it back somewhere that there is easy access to lots of LOX and LNG. If not then a stable situation where enough tankage could be brought in that enables storage for enough LOX/ LNG to then fully fuel the SS or enough to get it to a P2P platform. There is a lot of planning and contingencies that would be ironed out ahead of time for the rapid deployment cases. Practically a computer program the then tells you the steps needed to get the SS to the destination and what steps needed to get it back.

Offline Twark_Main

  • Senior Member
  • *****
  • Posts: 2301
  • Technically, we ALL live in space...
  • Liked: 1341
  • Likes Given: 885
Re: Starship Single Stage Earth Point to Point
« Reply #255 on: 10/11/2020 12:10 am »
[snip]

Note that the desired end product of liquification is not LNG but rather LCH4. The natural gas has to be cleaned/purified either before or after liquification. That or else the Raptors need to be certified to burn dirty fuel.

Yes, thank you. I meant to say that but it slipped my mind.

it would not be a small plant either, to process a tank load of LNG in 30 minutes.

AFAIK currently SpaceX sub-chills the LCH4 on-demand during prop loading, using a LCH4-to-LN2 heat exchanger. I presume they'd use a similar approach here.

Modest size air liquefaction plant provides a "slow drip" into LOX and LN2 tanks. I find it surprising that you only need a modest size pipeline and you can completely eliminate the on-site LCH4 tanks.
With a sufficient source of CH4 (gas). You can use it to manufacture the LOX and LN2 prior to the manufacture step for LNG to then do a full prop load of an SS.

The basic question is just how much equipment is needed and if it is worthwhile vs just trucking in enough prop to then fly the SS far enough that it can get to a facility that has LOX and LNG. A quick estimate calculation such that an SS without payload and loaded with ~300mt of prop could go as far as several 100km.  So after a couple of days of flying in the prop on C-130's you get the SS back to a regular large source of LOX and LNG. There it would be fully fueled and the go back to a full service P2P platform. Most cases would not need delivery of infrastructure to the SS location but just enough prop ~6 C-130 flights over a couple of days to get it back somewhere that there is easy access to lots of LOX and LNG. If not then a stable situation where enough tankage could be brought in that enables storage for enough LOX/ LNG to then fully fuel the SS or enough to get it to a P2P platform. There is a lot of planning and contingencies that would be ironed out ahead of time for the rapid deployment cases. Practically a computer program the then tells you the steps needed to get the SS to the destination and what steps needed to get it back.

I believe I recall calculating that 1 tonne of LNG, fed into generators, can make 10 tonnes of LOX. So if you import 350 tonnes of LCH4 + a transportable air liquefaction rig, the numbers should work out.

As long as the air liquefaction rig masses less than ~400 tonnes, the transport economics should work out. Note that I'm assuming that the rig will need to be transported there-and-back (notionally doubling the transport costs), while the fuel only needs to be transported one-way.
« Last Edit: 10/11/2020 12:11 am by Twark_Main »
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Online oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 4923
  • Florida
  • Liked: 4391
  • Likes Given: 783
Re: Starship Single Stage Earth Point to Point
« Reply #256 on: 10/11/2020 12:48 am »
There are a lot of possibilities. But the first Domino is to get P2P to work. Either as a single stage SS (intermediate range) or a two stage SH+SS (intercontinental range).

Online TheRadicalModerate

  • Senior Member
  • *****
  • Posts: 2724
  • Tampa, FL
  • Liked: 2010
  • Likes Given: 392
Re: Starship Single Stage Earth Point to Point
« Reply #257 on: 10/11/2020 10:22 pm »
There are a lot of possibilities. But the first Domino is to get P2P to work. Either as a single stage SS (intermediate range) or a two stage SH+SS (intercontinental range).

I was going to say that there's little doubt that the two-stage version will work P2P military applications, but then I started wondering if there's a minimum distance that Starship can fly.  As the distance gets shorter, the angle of entry gets steeper.  On the other hand, you need less energy.

There doesn't seem to be much doubt that longer flights can use hypersonic skip, which not only extends the range but affords a lot of leeway in terms of energy management.  But that won't work for short hops.

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9224
  • Australia
  • Liked: 4461
  • Likes Given: 1101
Re: Starship Single Stage Earth Point to Point
« Reply #258 on: 10/11/2020 10:28 pm »
I hope they spin off a company to operate these vehicles for the military, and the missile-detection Starlink system, etc.

Call it Stark Industries.

Human spaceflight is basically just LARPing now.

Offline RonM

  • Senior Member
  • *****
  • Posts: 3340
  • Atlanta, Georgia USA
  • Liked: 2222
  • Likes Given: 1584
Re: Starship Single Stage Earth Point to Point
« Reply #259 on: 10/12/2020 04:53 am »
There are a lot of possibilities. But the first Domino is to get P2P to work. Either as a single stage SS (intermediate range) or a two stage SH+SS (intercontinental range).

I was going to say that there's little doubt that the two-stage version will work P2P military applications, but then I started wondering if there's a minimum distance that Starship can fly.  As the distance gets shorter, the angle of entry gets steeper.  On the other hand, you need less energy.

There doesn't seem to be much doubt that longer flights can use hypersonic skip, which not only extends the range but affords a lot of leeway in terms of energy management.  But that won't work for short hops.

You don't need a suborbital vehicle for a short hop. Just send a C-17. Cruise speed is 830 km/h. Use the right tool for the job.

Tags:
 

Advertisement NovaTech
Advertisement SkyTale Software GmbH
Advertisement Northrop Grumman
Advertisement
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1