Author Topic: F9 Block 5 Updates and Discussion  (Read 269357 times)

Offline Mader Levap

  • Full Member
  • ****
  • Posts: 962
  • Liked: 429
  • Likes Given: 468
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #480 on: 02/20/2018 03:09 PM »
Man, people are trying to read a lot from something that has simpler explanation. ::)

It is just package that is octagonal, not rocket itself.
Be successful.  Then tell the haters to (BLEEP) off. - deruch
...and if you have failure, tell it anyway.

Offline robert_d

  • Full Member
  • **
  • Posts: 290
  • Liked: 43
  • Likes Given: 106
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #481 on: 02/20/2018 04:02 PM »
Could the following images be the first one of Block 5?
IIRC there was a comment that B5 would be immediately recognizable. To me, these cores no longer look completely round. It that what was meant by that comment?

Doesn't look like a regular octagon to me. I would speculate a transport frame of some sort - but possibly protecting something new external to the main tanks. Wild speculative question - Since legs extend the the cross section anyway would there be any gain to place the COPV's in external cowlings? Gives additional internal volume in the tanks and removes the issue of contact with the LOX.

Offline Stan-1967

  • Full Member
  • ****
  • Posts: 529
  • Denver, Colorado
  • Liked: 275
  • Likes Given: 186
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #482 on: 02/20/2018 04:06 PM »

As to an octagon not being ideal for a pressurized container, this is obviously true, but I don't see that it would be a show stopper, & the core is not pressurized that high ( 40psi?  A COPV it is not).   


You are forgetting head pressure and acceleration.  An octagon is a non starter

Not going to work with composite interstages.
I'm not forgetting those considerations. I just listed the considerations that would favor an octagon formfactor. I think the 6 items listed was worth "speculating" on, as this is the speculation thread.

Those more in the know than myself can easily list the factors that make it a bad idea.  I'm sure there are those here that have seen & worked on block 5 & know for certain, but they evidently are not sharing the details.  How many of those non starter ideas can be fixed with a few $100M in engineering trades?


Having said that, I have seen very little in this block 5 speculation thread that explains how F9 will get to the performance specs that were being tossed out by SpaceX.  Uprated engine thrust, at the same ISP,  eats into gravity losses & therefore increases performance, but total prop & increased vehicle GLOW seems to need to be increased.  Weight savings on the legs doesn't leverage much increase in payload to GTO.   Where is the performance coming from?

Offline acsawdey

  • Full Member
  • ***
  • Posts: 371
  • Minnesota
  • Liked: 218
  • Likes Given: 389
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #483 on: 02/20/2018 04:12 PM »
Having said that, I have seen very little in this block 5 speculation thread that explains how F9 will get to the performance specs that were being tossed out by SpaceX.  Uprated engine thrust, at the same ISP,  eats into gravity losses & therefore increases performance, but total prop & increased vehicle GLOW seems to need to be increased.  Weight savings on the legs doesn't leverage much increase in payload to GTO.   Where is the performance coming from?

Fly at higher angle of attack to reduce boostback burn?
Better thermal protection so less reentry burn is needed?
Partial powered extension of legs to use as an air brake, reducing landing burn?
More reliable start and throttle control to reduce the length of the landing burn even further, shaving off gravity loss?

Offline Stan-1967

  • Full Member
  • ****
  • Posts: 529
  • Denver, Colorado
  • Liked: 275
  • Likes Given: 186
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #484 on: 02/20/2018 04:30 PM »

You are forgetting head pressure and acceleration.  An octagon is a non starter

Not going to work with composite interstages.

My deal killer for an octagon vehicle is not the engineering problems, I bet they could be solved, but I see zero chance you try something like this on the vehicle you are going to use for commercial crew.  ASAP would laugh SpaceX out of contention.

Again, my 6 points were just speculating on how an octagon has some theoretical advantages consistent with the statements from SpaceX.

Offline Basto

  • Full Member
  • *
  • Posts: 156
  • Salt Lake City, UT
  • Liked: 141
  • Likes Given: 201
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #485 on: 02/20/2018 05:41 PM »
Regarding the “octagonal” appearance. It is just how they wrap the cores. Here is an older core photo that has a similar shape.

https://twitter.com/ikluft/status/534266046920654848?s=12

Offline Rabidpanda

  • Full Member
  • ****
  • Posts: 500
  • Liked: 86
  • Likes Given: 568
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #486 on: 02/20/2018 09:13 PM »

You are forgetting head pressure and acceleration.  An octagon is a non starter

Not going to work with composite interstages.

My deal killer for an octagon vehicle is not the engineering problems, I bet they could be solved, but I see zero chance you try something like this on the vehicle you are going to use for commercial crew.  ASAP would laugh SpaceX out of contention.

Again, my 6 points were just speculating on how an octagon has some theoretical advantages consistent with the statements from SpaceX.

An octagonal pressure vessel would to be significantly heavier than a cylindrical pressure vessel, all else being equal. That is the deal breaker. It could be made safe, it could be qualified to fly crew, it would just be extremely inefficient and the extra weight would far outweigh any small packaging advantages.

Offline gregpet

  • Member
  • Posts: 49
  • Liked: 14
  • Likes Given: 42
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #487 on: 02/24/2018 06:54 PM »
SpaceX has stated that Block 5 will be "the final version" of F9, and clearly SpaceX wants to move on to the BFR.

There were comments (from Spacex) about a new leg design, changes for rapid reusability, an update to the Merlin engines to address known issues, and I believe a thrust increase.

What we don't know is what they're planning to include with F9B5

Will F9B5 have features that will help with BFR development (e.g. an option for cradle landing?)
Will there be provisions for barge fly-back? (as per an isolated comment from Musk a while back?)

Also in-scope: FHB5

Stay tuned!

Can you truly have the kind of rapid re-usability that Elon talks about without a cradle style landing?  Just lifting the S1 and resetting legs (regardless of design) would seem like a non-trivial, time consuming procedure.

If they move towards cradle landings for S1, I would assume that we would see it first on barge landing attempts (for obvious reasons).

Online speedevil

  • Senior Member
  • *****
  • Posts: 2059
  • Fife
  • Liked: 1009
  • Likes Given: 1132
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #488 on: 02/24/2018 07:03 PM »
Can you truly have the kind of rapid re-usability that Elon talks about without a cradle style landing?  Just lifting the S1 and resetting legs (regardless of design) would seem like a non-trivial, time consuming procedure.

Why?
Container cranes - some of the larger ones - routinely carry payloads of similar masses around at high speed.
The 'octograbber' type idea in principle could also rapidly and quickly position a stage.
Even if you look at actual current manual procedures of getting the S1 off the barge, they're remarkably faster than they were.

In principle there seems little stopping the F9 landing very near the launchpad, being rapidly checked out, and relaunched well within a week - at least - the 'get the empty stage to a known consistent position' is not a limiter.

No, you're not going to do passenger launches of it ten times a day. (probably)
« Last Edit: 02/24/2018 07:07 PM by speedevil »

Offline gregpet

  • Member
  • Posts: 49
  • Liked: 14
  • Likes Given: 42
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #489 on: 02/25/2018 05:51 PM »
If you are talking about weeks or even a week I think you are right, but Elon uses words like "rapid" re-usability. To get to rapid I still think the use of legs are going to be awkward and slow.  Not to mention a cradle saves  weight (no legs) and better fault tolerance (malfunctioning leg).

Clearly SpaceX is moving to cradles since this is how the BFR will be landing.  The only question is whether the Falcon 9 will eventually land on a cradle.  It would also seem reasonable to learn cradle landings with the Falcon 9 instead of the much larger BFR.  The landing accuracy of the current Falcon 9 is already pretty amazing...


   

Can you truly have the kind of rapid re-usability that Elon talks about without a cradle style landing?  Just lifting the S1 and resetting legs (regardless of design) would seem like a non-trivial, time consuming procedure.

Why?
Container cranes - some of the larger ones - routinely carry payloads of similar masses around at high speed.
The 'octograbber' type idea in principle could also rapidly and quickly position a stage.
Even if you look at actual current manual procedures of getting the S1 off the barge, they're remarkably faster than they were.

In principle there seems little stopping the F9 landing very near the launchpad, being rapidly checked out, and relaunched well within a week - at least - the 'get the empty stage to a known consistent position' is not a limiter.

No, you're not going to do passenger launches of it ten times a day. (probably)

Offline rsdavis9

Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #490 on: 02/26/2018 01:27 PM »
I think the addition of thrusters top and bottom on the BFR make a cradle landing a lot easier. For the f9 to do a horizontal adjustment it needs to tip to change the thrust vector from vertical. With BFR a small horizontal adjustment can be done with thrusters top and bottom moving it sideways with out the need to tip. Almost the same problem as with boats. The addition of thrusters allows a boat to move to a dock sideways without changing the boats heading.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline Eerie

  • Member
  • Full Member
  • ****
  • Posts: 771
  • Liked: 123
  • Likes Given: 7
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #491 on: 02/26/2018 03:43 PM »
Octagon rockets are not crazy enough. Triangular prism is clearly the best shape.

Offline Norm38

  • Full Member
  • ****
  • Posts: 1104
  • Liked: 467
  • Likes Given: 656
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #492 on: 02/28/2018 05:36 PM »
https://www.nasaspaceflight.com/2018/02/first-falcon-9-block-5-readying-static-fire-mcgregor-rapid-reuse/
Quote
NASA is requiring SpaceX to fly a “frozen” configuration of the Block 5 – meaning every vehicle is built the same way – successfully for at least 7 flights.

This seems to be an arbitrary requirement.  Based on what?  Certainly not based on any practice NASA itself followed.
And is it truly that SpaceX must build and fly 7 separate cores?  Or can some of those 7 be re-flights?

Online speedevil

  • Senior Member
  • *****
  • Posts: 2059
  • Fife
  • Liked: 1009
  • Likes Given: 1132
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #493 on: 02/28/2018 06:12 PM »
And is it truly that SpaceX must build and fly 7 separate cores?  Or can some of those 7 be re-flights?

This is not a particularly onerous requirement.
They have 25 or so (I have not checked) launches till the end of the year, before crew is supposed to fly, even a third of those being new cores would work.

Especially as they're building up a stock of block 5s, that they want to use till the BFS (and maybe BFR) is ready.

Offline matthewkantar

  • Full Member
  • ****
  • Posts: 785
  • Liked: 505
  • Likes Given: 579
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #494 on: 03/10/2018 03:24 PM »
Just a little bit of speculation here, I bet SpaceX is going to want to turn around and reuse the first Block 5 booster ASAP, putting the new capability on display. With the launch tempo they are getting into there will be plenty of opportunities. Relaunching a booster a week after its first flight would turn heads.

Online AncientU

  • Senior Member
  • *****
  • Posts: 6120
  • Liked: 3916
  • Likes Given: 5402
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #495 on: 03/10/2018 04:15 PM »
The quick turn-around may follow a few flights/reflights of Block 5.
Should take the time to check that your design is performing as planned.
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline IanThePineapple

Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #496 on: 03/10/2018 04:18 PM »
The quick turn-around may follow a few flights/reflights of Block 5.
Should take the time to check that your design is performing as planned.

Yeah, I owuldn't be surprised if they did a teardown of the first one or two cores post-landing, similar to what is done with the FT cores for refurb.

Check every little spot for issues.

Online guckyfan

  • Senior Member
  • *****
  • Posts: 6653
  • Germany
  • Liked: 1721
  • Likes Given: 1666
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #497 on: 03/10/2018 05:00 PM »
The quick turn-around may follow a few flights/reflights of Block 5.
Should take the time to check that your design is performing as planned.

Yeah, I owuldn't be surprised if they did a teardown of the first one or two cores post-landing, similar to what is done with the FT cores for refurb.

Check every little spot for issues.

They have done that very thoroughly on the landed boosters already. They have identified spots that don't hold up very well and/or are not easily refurbished. They have upgraded those spots. They now need to check how the upgrades hold up to expectations. That does not need redoing the full inspection of the vehicle. That will come after 3 or 4 flights probably.

Offline wannamoonbase

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 2983
  • Denver, CO
    • U.S. Metric Association
  • Liked: 684
  • Likes Given: 1125
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #498 on: 03/10/2018 07:07 PM »
The quick turn-around may follow a few flights/reflights of Block 5.
Should take the time to check that your design is performing as planned.

Yeah, I owuldn't be surprised if they did a teardown of the first one or two cores post-landing, similar to what is done with the FT cores for refurb.

Check every little spot for issues.

They have done that very thoroughly on the landed boosters already. They have identified spots that don't hold up very well and/or are not easily refurbished. They have upgraded those spots. They now need to check how the upgrades hold up to expectations. That does not need redoing the full inspection of the vehicle. That will come after 3 or 4 flights probably.

I think you're being optimistic.  These are rockets after all.  They have experience people now and will have things they specifically want to check.  I think they will be very thorough on the first ones.  At a minimum to confirm their expectations and establish baselines for the new vehicles.
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 10068
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 6895
  • Likes Given: 4681
Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #499 on: 03/10/2018 11:28 PM »
Maybe they will put some clear coat on the CF, like car manufacturers do...
But why, when the whole point of using that material is to reduce weight?
The point is to find the right balance between weight and cost. Carbon fiber with a clear coat may weigh less than carbon fiber with regular paint, and outperform (durabilitywise) uncoated.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Tags: