Author Topic: F9 - S2 reusable modification as evolution steps to BFS(ITS)  (Read 41725 times)

Offline Xentry

  • Full Member
  • *
  • Posts: 146
  • Lisbon, Portugal
  • Liked: 8
  • Likes Given: 8
Re: F9 - S2 reusable modification as evolution steps to BFS(ITS)
« Reply #220 on: 10/13/2017 03:01 PM »
The one thing that does make sense is putting a delta wing and BFS style heatshield on S2.
Or mount body flaps (Shuttle and IXV-like) plus heatshield.

Offline Xentry

  • Full Member
  • *
  • Posts: 146
  • Lisbon, Portugal
  • Liked: 8
  • Likes Given: 8
Re: F9 - S2 reusable modification as evolution steps to BFS(ITS)
« Reply #221 on: 10/13/2017 03:10 PM »
What they don't do: add delta wings or flaps or otherwise significantly alter the aerodynamics of the stage.

Edit: At least that's what KSP taught me. Once a rocket is stable and controllable to orbit, leave it alone.
They'll probably need some aerodynamic control surfaces to keep the stage stable during reentry (bring CoP behind c.g + provide pitch control), especially since BFS will reenter in much the same attitude. Easiest would be to add body flaps. Then they could even start testing how different shapes/configurations of body flaps could better thermally shield the S2 engine bell, as will be needed for BFS.

Online octavo

  • Member
  • Posts: 65
  • Liked: 24
  • Likes Given: 49
Re: F9 - S2 reusable modification as evolution steps to BFS(ITS)
« Reply #222 on: 10/13/2017 03:22 PM »
What they don't do: add delta wings or flaps or otherwise significantly alter the aerodynamics of the stage.

Edit: At least that's what KSP taught me. Once a rocket is stable and controllable to orbit, leave it alone.
They'll probably need some aerodynamic control surfaces to keep the stage stable during reentry (bring CoP behind c.g + provide pitch control), especially since BFS will reenter in much the same attitude. Easiest would be to add body flaps. Then they could even start testing how different shapes/configurations of body flaps could better thermally shield the S2 engine bell, as will be needed for BFS.
I must be wrong, because the delta wings seems to be a popular idea on this thread. I'm skeptical because I think it would require recalculating the ascent and is too risky to fly with a commercial payload.

Offline Xentry

  • Full Member
  • *
  • Posts: 146
  • Lisbon, Portugal
  • Liked: 8
  • Likes Given: 8
Re: F9 - S2 reusable modification as evolution steps to BFS(ITS)
« Reply #223 on: 10/13/2017 04:24 PM »
They'll probably need some aerodynamic control surfaces to keep the stage stable during reentry (bring CoP behind c.g + provide pitch control), especially since BFS will reenter in much the same attitude. Easiest would be to add body flaps. Then they could even start testing how different shapes/configurations of body flaps could better thermally shield the S2 engine bell, as will be needed for BFS.
I must be wrong, because the delta wings seems to be a popular idea on this thread. I'm skeptical because I think it would require recalculating the ascent and is too risky to fly with a commercial payload.
Body flaps would probably have a similar aerodynamically destabilizing effect as the grid fins at the top of S1, since they wouldn't need to be much bigger, would be flush with the surface of F9, and would be just a few metres further up along the rocket's surface. However, you may be right that the ascent profile need to be recalculated, and that the feasibility of using small wings, or fins, or something equivalent, is not guaranteed.

Offline obi-wan

  • Full Member
  • **
  • Posts: 261
  • Liked: 579
  • Likes Given: 5
Re: F9 - S2 reusable modification as evolution steps to BFS(ITS)
« Reply #224 on: 10/14/2017 03:28 PM »
Im not serious in this case but I think there is an interesting topic in how they look after the massive TPS surface on the future BFS. I imagine something highly automated that just scans every inch. (ps: also zero qualifications )
Various options were considered for Shuttle but never implemented.  The Shuttle TPS data base showed tile replacement costs of $12 000/m^2 and blanket replacement of $3 000 /m^2. Translated to BFS that's a lot of money. PICAX --> bigger tiles + cheaper (AFAIK) but still likely to be high if enough acreage needs to changed every flight.

One was a (more or less) repurposed pets RFID tag with a fusible link that was small enough to drop into the gaps between the tiles. Area overheats, link melts and circuit broken. Best of all no batteries to replace and it's management by exception.

Carnegie Mellon wanted to do a robot inspection frame (like a car wash)  with a set of sensors on a scanner head checking for both surface damage (visible light) and sub surface damage. NASA feared damaging the orbiters (and I think the cost).

[clipped]
CMU _did_ build a robot for tile work on the orbiter under the support of the NASA robotics technology program, which was capable of measuring "step and gap" (how far apart the tiles are, and what's the difference in surface heights at adjacent points) and injecting waterproofing compound so the tile wouldn't absorb water on the pad. To give you an idea of the complexity of this problem, after each flight NASA measured step and gap at three places between each set of adjacent tiles, and due to the installation pattern most tiles had six adjacent tiles. That's 36 measurements for 20,922 tiles on Columbia (but there were somewhat fewer on later vehicles.) There was a small ~3/4in circle somewhere on each tile denoting a hole for injecting the waterproofing fluid. Each tile was identified by a serial number which had to be verified for each inspection; however, with multiple flights, the lettering wore/burned off; frequently the identity of a tile had to be inferred by finding tiles 5-6 tiles away with readable numbers, then counting off tiles on a map of the surface.

The CMU robot did both the step-and-gap measurements and the waterproofing on a test panel in a KSC lab, but NASA was totally paranoid about the potential of a large robot accidentally damaging tiles when it took three people a day to replace one, so it was never allowed near the actual vehicles.

Moral of the story: don't use silica tiles for TPS.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 6180
  • Everyplaceelse
  • Liked: 822
  • Likes Given: 5137
Re: F9 - S2 reusable modification as evolution steps to BFS(ITS)
« Reply #225 on: 10/15/2017 11:26 AM »
CMU _did_ build a robot for tile work on the orbiter under the support of the NASA robotics technology program, which was capable of measuring "step and gap" (how far apart the tiles are, and what's the difference in surface heights at adjacent points) and injecting waterproofing compound so the tile wouldn't absorb water on the pad. To give you an idea of the complexity of this problem, after each flight NASA measured step and gap at three places between each set of adjacent tiles, and due to the installation pattern most tiles had six adjacent tiles. That's 36 measurements for 20,922 tiles on Columbia (but there were somewhat fewer on later vehicles.) There was a small ~3/4in circle somewhere on each tile denoting a hole for injecting the waterproofing fluid. Each tile was identified by a serial number which had to be verified for each inspection; however, with multiple flights, the lettering wore/burned off; frequently the identity of a tile had to be inferred by finding tiles 5-6 tiles away with readable numbers, then counting off tiles on a map of the surface.
I was not sure quite how far they had got in developing this. I was sure it had never been actually deployed.
Quote from: obi-wan
The CMU robot did both the step-and-gap measurements and the waterproofing on a test panel in a KSC lab, but NASA was totally paranoid about the potential of a large robot accidentally damaging tiles when it took three people a day to replace one, so it was never allowed near the actual vehicles.
[EDIT Odd. In industry SOP is to fit AGV with "bumper switches" that cut power if they hit something. I find it very hard to believe it would impossible to find a design that won't cut the power fast enough. I find it even harder to believe the moving sensor package would have so much inertia that it would still hit the tile. When you realize 3 employees are $450K a  year to fully support you can put a lot of effort into doing this, if you care about costs. ]


Indeed. Very much a case of "supporting a design" (after all the key choices had been made) rather than "designing the support."  :(



Quote from: obi-wan
Moral of the story: don't use silica tiles for TPS.
Indeed.  It looks like SX have avoided any such use.
« Last Edit: 10/16/2017 04:57 PM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Tags: