Jump to content

SpaceX Discussion Thread


Skylon

Recommended Posts

On 18/10/2017 at 1:50 PM, MatterBeam said:

With its 375s Isp Raptor engines, it has 9693m/s of deltaV. RSS players know you can reach orbit with about 9400m/s of deltaV

Im a RSS player and i barely can even get to orbit with 10km/s :P

USAF found another launch vehicle to launch their spysats on?

Link to comment
Share on other sites

38 minutes ago, Exoscientist said:

 

 The SpaceX BFR tanker can serve as a reusable SSTO by switching to a winged, horizontal landing mode:

SpaceX BFR tanker as an SSTO.

https://exoscientist.blogspot.com/2017/10/spacex-bfr-tanker-as-ssto.html

 

  Bob Clark

Two issues, first is ISP and trust will not be vacuum with atmospheric engines, yes you can add two vacuum engines you fire up then high enough and then shut down the atmospheric ones as you get lighter and don't need the trust anymore, the data looks pretty good as in 25 ton payload to 400 km with 360 in ISP and 50 ton dry mass.

An winged option is interesting, yes you save fuel, also larger surface area for reentry making heat shield thinner. Downside is an unique craft but the ssto will be an new craft anyway, you want spare fuel for an escape to orbit option if problems like loosing engine at launch, not sure how much fuel it will need to land as its suposed to use drag until subsonic. 

Link to comment
Share on other sites

11 hours ago, CatastrophicFailure said:

Announced right after BO’s engine update, hmm... :sealed:

A good thing! It just goes to show how much SpaceX has shaken up the market by moving it back into the competitive industry it should have always been. It means that there are multiple players and the US Government is not the sole source of money - in other words, spending your R&D budget on lobbyists is no longer a winning move. 

9 hours ago, Exoscientist said:

Perhaps they see the advantage of such a BFR point-to-point transport.   

http://www.astronautix.com/i/ithacus.html 

  Bob Clark

Maybe the BFR won't be allowed to carry civilians for a long time or even land near cities, but rapid transport of 100 tons of cargo is very valuable. Imagine shortening the supply chain on valuable items to 30 minutes! Troops will accept risks civilians won't, so good idea. 

1 hour ago, Exoscientist said:

 

 The SpaceX BFR tanker can serve as a reusable SSTO by switching to a winged, horizontal landing mode:

SpaceX BFR tanker as an SSTO.

https://exoscientist.blogspot.com/2017/10/spacex-bfr-tanker-as-ssto.html

 

  Bob Clark

Reading that. Will comment.

Link to comment
Share on other sites

2 hours ago, MatterBeam said:

Maybe the BFR won't be allowed to carry civilians for a long time or even land near cities, but rapid transport of 100 tons of cargo is very valuable. Imagine shortening the supply chain on valuable items to 30 minutes!

This. This is where I think the initial market for rapid point-to-point transportation is. The first such BFS’s will be painted brown, blue & orange, not airline white. My wife works in the industry, and she agrees there’s definitely a niche waiting to be filled there. There are lots of times when goods need to be there now and cost is really no object. Ie, right now there’s really no such thing as overnight cargo from Seattle to Singapore. 

Link to comment
Share on other sites

11 minutes ago, Ultimate Steve said:

I just want a T-shirt that truthfully says "THIS T-SHIRT HAS BEEN IN SPACE." I'd pay $1000 for it, no joke.

I want a shirt that is covered in moon regolith, or a packet of moon dust that i can throw on people wich gives me the ability easily rip open their skin.

Edited by NSEP
Link to comment
Share on other sites

20 hours ago, CatastrophicFailure said:

This. This is where I think the initial market for rapid point-to-point transportation is. The first such BFS’s will be painted brown, blue & orange, not airline white. My wife works in the industry, and she agrees there’s definitely a niche waiting to be filled there. There are lots of times when goods need to be there now and cost is really no object. Ie, right now there’s really no such thing as overnight cargo from Seattle to Singapore. 

This happens from time to time in automotive. Like, it's cheaper to fill up the corporate jet with tail light assemblies and fly it to Mexico than to have the assembly line stop due to a parts shortage. So yes, literally chartering a jet to get parts on time is cheaper than having an assembly line stoppage.

Link to comment
Share on other sites

I think so, yeah. But the goal of effectively no refurb is what I was expecting given a "24 hour turn around" that they say they are going for. So a team of XX people, working 3 man-days each (8 hr days) is the total cost to refly a 1st stage. That's not a lot of money, even at ridiculously high rates.

Link to comment
Share on other sites

On 10/22/2017 at 10:19 AM, Exoscientist said:

SSTO

Elon Musk has confirmed that the BFR is an SSTO without the booster, no need for winged landing.  It can't carry any cargo though.  The spaceship will be launched by itself as the worlds second(ARCA will launch next year) SSTO before the booster is finished.  

Link to comment
Share on other sites

5 hours ago, DAL59 said:

Elon Musk has confirmed that the BFR is an SSTO without the booster, no need for winged landing.  It can't carry any cargo though.  The spaceship will be launched by itself as the worlds second(ARCA will launch next year) SSTO before the booster is finished.  

 

 Actually what he said in the video presentation is that the BFR upper stage can be SSTO but the full two-stage BFR can carry more than an order of magnitude more payload. Since the payload for the reusable two-stage BFR is 150 tons, the payload for the BFR upper stage as a reusable SSTO might be, say, 10 to 15 tons.

 Part of the calculation in my blog post was to suggest using winged landing for the SSTO you might lose less of the payload in the reusable case. I estimate less than 10% loss with winged landing, as opposed to 70% to 80% loss with the vertical, propulsive landing approach. 

 If this is true you might want to make also the lower stage do a winged landing. For instance if the 10% loss using winged landing also holds for the two-stage BFR, then instead of losing 40% payload from 250 tons to 150 tons for reusability, it would be only 10% loss from 250 tons to 225 tons. So it is important to do such trades between the different landing modes to see which would result in the smallest loss in payload for reusability.

 

  Bob Clark

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...