Author Topic: F9 Block 5 Updates and Discussion  (Read 277037 times)

Offline livingjw

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #280 on: 05/07/2017 08:58 PM »
Grid fins will most likely be forged to near net shape then CNC'd. Similar to this hip joint, but much larger forge.
They probably will start with a plate rather than the bar you see in the video.
« Last Edit: 05/07/2017 09:01 PM by livingjw »

Online LouScheffer

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #281 on: 05/08/2017 01:31 AM »
F9 Block 5 is turning into quite a capable machine...

Quote
In terms of trends, Shotwell sees a trend of a bifurcation in the market. She says there are a couple of satellite providers making their satellites bigger. “Some of that is basically putting a giant satellite on Falcon 9 with a lot of propellant, which would normally be a very heavy satellite, even potentially hard for Falcon 9 to throw. But when you put so much propellant on that satellite, they can get themselves to orbit even from a sub-synch. A couple of manufacturers are doing that … [sending] an over 7-ton satellite on Falcon 9 to GTO. We are seeing a number of satellite manufacturers come around and do that just because of the value proposition presented by Falcon 9.”

http://interactive.satellitetoday.com/via/april-2017/shotwell-ambitious-targets-achievable-this-year/
Here's a numerical example to explain how this might work.  With the current incarnation of the Falcon 9, it looks like the heaviest payload it can get to a normal apogee GTO is about 6 tonnes.  This based on the observed orbit of the 5.5t Echostar 23.  The observed inclination reduction took about 200 m/s over a minimal GTO.  Raising the mass to 6t will use up this margin, so let's guess 6t to a normal apogee GTO.

Now examine the consequences of going up to 7.5 tonnes.  Assume the second stage masses 4.5t, fuel 11.5t, plus payload.  Then going from 6t to  7.5t will cost you 348*9.8*(ln(122/10.5) - ln(123.5/12) ), or about 414m/s.  The extra mass also loses about 22 m/s from the first stage, for a total deficit of roughly 438 m/s short of GTO.  Now how much fuel to you need to burn to get this back?  Bi-propellant liquid apogee motors have an ISP of about 320.  So you need to burn 1 tonne of fuel to get 320*9.8*ln(7.5/6.5) = 448 m/s.  Voila!  You now have a 6.5 tonne satellite in a normal apogee GTO.  You've gained 500 kg of performance.  (Note that this maneuver involves using the apogee motor at perigee.  Except for name confusion this is not a problem.)


Offline gospacex

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #282 on: 05/08/2017 12:48 PM »
Basically you are saying that it makes sense to develop a kick stage (small third stage) for F9.

Offline ChrML

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #283 on: 05/08/2017 12:51 PM »
I'm pretty certain B5 will only focus on: Fly reliably and often.

No new features, no changes in performance (except to counter eventually added weight due to fairing reuse mm..).

SpaceX has good rockets, but have yet to prove they can fly as often as they say they will. Whatever is preventing them from flying that often, is what will be improved in B5.

- Less refurbish before reuse
- Parts that are easier to produce or easier to assemble
- Production and asaembly optimizations
- Fairing reuse
- Bugs and mishaps from B4

Then they need to fly that same design atleart 50 times the next 2 years to earn some money for ITS and be allowed to do manned missions.

Online Robotbeat

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #284 on: 05/08/2017 12:57 PM »
B5 will absolutely add performance. Block 5 figures are on the website now, and SpaceX has not approached those, yet. Thrust increases for certain.
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Offline Celestar

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #285 on: 05/08/2017 01:27 PM »
Basically you are saying that it makes sense to develop a kick stage (small third stage) for F9.

That'd be fun. We could then be discussing how to land the kick stage ;)

Celestar

EDIT: Typo
« Last Edit: 05/08/2017 01:39 PM by Celestar »

Offline AncientU

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #286 on: 05/08/2017 01:38 PM »
B5 will absolutely add performance. Block 5 figures are on the website now, and SpaceX has not approached those, yet. Thrust increases for certain.

Website thrust figures are still 171,000lbf -- Block 5 was 190,000lbf, right?
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Online abaddon

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #287 on: 05/08/2017 02:15 PM »
Basically you are saying that it makes sense to develop a kick stage (small third stage) for F9.
AIUI making the fuel tank bigger isn't particularly expensive, it's just something you need to plan for that's different from other LVs.  I guess as a downside it might make it harder to move off to another LV, but the practical difference between 6 and 7 tonnes doesn't seem to change the equation in that respect, you'd need to go to a Proton or Ariane V upper berth in either case.

What it means is some operators/manufacturers are aligning at least some of their designs with what Falcon 9 can provide.  The dual all-electric Boeing satellites (F9 has launched two) were an early example of that but haven't really made much headway.  This is another example.  Will be interesting to see if others follow suit.

Online abaddon

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #288 on: 05/08/2017 02:17 PM »
B5 will absolutely add performance. Block 5 figures are on the website now, and SpaceX has not approached those, yet. Thrust increases for certain.
Aren't those speculated to be Block 4 changes?  Meaning, the actual "full thrust" will come before the "finalized" Block 5 design flies.

Offline Rebel44

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #289 on: 05/08/2017 02:18 PM »
B5 will absolutely add performance. Block 5 figures are on the website now, and SpaceX has not approached those, yet. Thrust increases for certain.

Website thrust figures are still 171,000lbf -- Block 5 was 190,000lbf, right?

You missed a 0 (number is for 1st stage)
Thrust at sea level: 7 607kN / 1 710000 lbf
1 710 000 / 9 = 190 000

Offline Toast

Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #290 on: 05/08/2017 06:59 PM »
Website thrust figures are still 171,000lbf -- Block 5 was 190,000lbf, right?

AFAIK Block 5 thrust numbers are still unknown.

Offline Norm38

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #291 on: 05/10/2017 04:18 PM »
- Parts that are easier to produce or easier to assemble
- Production and asaembly optimizations

Actually, reuse makes these factors less important than for an expendable.  Expendable rockets need to be produced as cheaply as possible, as they can only be sold once.  A reusable rocket can be harder to assemble with parts that are more difficult/expensive to make.  Because that cost is amortized over many launches.

For example the new titanium grid fins are probably harder to make than the aluminum ones.  But since they won't slag on reentry, it's worth it.

Offline AncientU

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #292 on: 05/10/2017 05:43 PM »
- Parts that are easier to produce or easier to assemble
- Production and asaembly optimizations

Actually, reuse makes these factors less important than for an expendable.  Expendable rockets need to be produced as cheaply as possible, as they can only be sold once.  A reusable rocket can be harder to assemble with parts that are more difficult/expensive to make.  Because that cost is amortized over many launches.

For example the new titanium grid fins are probably harder to make than the aluminum ones.  But since they won't slag on reentry, it's worth it.

Especially if they save time during post-launch turnaround.  Inspecting grid fins and determining if they needed to be replaced each launch adds time... as does replacing them.  Forged titanium could be an install once and forget item.
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Offline Dante2121

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #293 on: 05/12/2017 03:03 AM »
- Parts that are easier to produce or easier to assemble
- Production and asaembly optimizations

Actually, reuse makes these factors less important than for an expendable.  Expendable rockets need to be produced as cheaply as possible, as they can only be sold once.  A reusable rocket can be harder to assemble with parts that are more difficult/expensive to make.  Because that cost is amortized over many launches.

For example the new titanium grid fins are probably harder to make than the aluminum ones.  But since they won't slag on reentry, it's worth it.

Especially if they save time during post-launch turnaround.  Inspecting grid fins and determining if they needed to be replaced each launch adds time... as does replacing them.  Forged titanium could be an install once and forget item.

Or even detach after x uses and put on a new rocket

Offline RDMM2081

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #294 on: 05/12/2017 06:02 PM »
My burning question about refurbished boosters is along the lines of "once it is refurbished once, does it require the same level of refurbishment again for its third flight?".  My completely uninformed speculation is that refurbishing a block 3 makes it into something else entirely, not block 3 anymore, and not block 4, and I don't want to muddy the waters any further so I'll leave it at that, "something else".  Once it is a "something else" version, could it be that the refurb is now down near the fabled "gas-n-go" levels?  I think they will still not be there until the first block 5.3 (the .3 is intended to indicate the third flight of a true block 5-off-the-assembly-line booster, not a revision within the block), but that we may be seeing the first hints of that in the reflown boosters.  I will be watching 1029.2/BulgariaSat with great interest, 1029.3 could be very informative.  It's almost a shame that 1021.2/SES-10 got to retire (visiting this core wherever it ends up is now officially on my bucket list, however). 

I also think that the FH side boosters are intended to fly several times in their current configs ("something else"), and I suspect that we will see some very fast turnaround times on those, and higher flight counts than the other reflown block 3 cores.

To keep this all more closely related to the block 5 OP, one thing I haven't heard much about is that block 5 could be the lightest core yet.  They have launched enough times, and assumingly kept the stages heavily instrumented, and overbuilt in some ways.  Wouldn't block 5 be the perfect time to finally strip out some of the excess and cut down to "fighting weight" so to speak?  The data has been gathered, the results are in, the design is more or less "locked" in block 5 right?  I'm not proposing drastic cuts to structural margins, but there must be something they can trim to eke a little more pmf rather than just relying on thrust increases or prop densification.

I think what I'm proposing here is that similar to Intel, block 4 may be a "tick" cycle (increase performance/capability) and block 5 may be the "tock" (refinement/streamline) cycle.  Did we already see this with 1.1 -> 1.2 and didn't realize it? Or were there simply too many changes all at once to put labels like that on those revisions?

Offline gospacex

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #295 on: 05/12/2017 06:12 PM »
You are over-analyzing it.

Offline RDMM2081

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #296 on: 05/12/2017 06:26 PM »
Isn't that what we do here?

Online Kansan52

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #297 on: 05/12/2017 06:45 PM »
My burning question ...

My uninformed opinion, they do what they need for a successful refurb while applying lessons learned. No block numbering.

Block 5 likely is applying weight reduction but we may never know.

Offline macpacheco

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #298 on: 05/12/2017 06:46 PM »
My burning question about refurbished boosters is along the lines of "once it is refurbished once, does it require the same level of refurbishment again for its third flight?".  My completely uninformed speculation is that refurbishing a block 3 makes it into something else entirely, not block 3 anymore, and not block 4, and I don't want to muddy the waters any further so I'll leave it at that, "something else".  Once it is a "something else" version, could it be that the refurb is now down near the fabled "gas-n-go" levels?  I think they will still not be there until the first block 5.3 (the .3 is intended to indicate the third flight of a true block 5-off-the-assembly-line booster, not a revision within the block), but that we may be seeing the first hints of that in the reflown boosters.  I will be watching 1029.2/BulgariaSat with great interest, 1029.3 could be very informative.  It's almost a shame that 1021.2/SES-10 got to retire (visiting this core wherever it ends up is now officially on my bucket list, however). 

I also think that the FH side boosters are intended to fly several times in their current configs ("something else"), and I suspect that we will see some very fast turnaround times on those, and higher flight counts than the other reflown block 3 cores.

To keep this all more closely related to the block 5 OP, one thing I haven't heard much about is that block 5 could be the lightest core yet.  They have launched enough times, and assumingly kept the stages heavily instrumented, and overbuilt in some ways.  Wouldn't block 5 be the perfect time to finally strip out some of the excess and cut down to "fighting weight" so to speak?  The data has been gathered, the results are in, the design is more or less "locked" in block 5 right?  I'm not proposing drastic cuts to structural margins, but there must be something they can trim to eke a little more pmf rather than just relying on thrust increases or prop densification.

I think what I'm proposing here is that similar to Intel, block 4 may be a "tick" cycle (increase performance/capability) and block 5 may be the "tock" (refinement/streamline) cycle.  Did we already see this with 1.1 -> 1.2 and didn't realize it? Or were there simply too many changes all at once to put labels like that on those revisions?

This is just educated speculation, nothing more. I won't even put hedging words since all conclusions are clearly my (rocket chair engineer) own.

There's a huge gap between what SpaceX knows a Block III strictly needs in refurb vs what they did on the SES10 booster and what they're doing for the next few ones. They're playing it ultra safe. They replaced everything that was cheap or somewhat cheap just in case.
They will gradually reduce blind replacement of more expensive items where margins are big enough towards a more economical process.
There's also the learning curve where the people doing the refurb work just need less time to get the same work done with practice.
If refurb costs <20% of a new booster, its an awesome return for SpaceX on the first few ones.
Since Block IV aren't flying yet (to the best of our knowledge), we can probably forget about such changes in current refurb efforts.
Block IV redesigns are likely the lowest hanging fruits that was easiest to complete in shorter time, while Block V the more complex changes that requires more verification and testing.
So far the word on the M1D thrust is that SpaceX is just sandbagging the performance and Block IV and V thrust upgrades are not the result of changes, but just that so far there's enough performance and they don't want to risk in flight failures regardless of the engines being able to handle Block V thrust in testing.

The number of recovered boosters that are safe to refurb and fly is higher than the number of reflights signed up.
The BulSat launch asked for the Iridium booster cause it had a fairly gentle recovery, which makes the customer more comfortable.
Do not discount customer psychology, specially when it comes to the customers that don't have expert rocket engineers in their payroll.
Its likely customers will ask for boosters launched into LEO, specially the ones launched onto an ASDS (even more gentle re-entry and landing).
Once enough successful reflights, customers will be increasingly confident in just taking SpaceX's words for it.
Insurance money is never the same as the payload in orbit producing its full revenue, and satellite operators aren't known for being as adventurous as SpaceX.

So I am predicting SpaceX will only fly the same boosters 3 or more times with Block IV, even then the goal of 10 flights will likely only be achieved with Block V.
Lots of boosters landed in hot GTO launches will be remanufactured into FH boosters.

The tick / tock thing doesn't make much sense if the deal is simply SpaceX gradually opening up the throttle rather than having to make changes for the higher thrust.
« Last Edit: 05/12/2017 06:54 PM by macpacheco »
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Offline wannamoonbase

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Re: F9 Block 5 Updates, Discussions, and Speculations
« Reply #299 on: 05/12/2017 07:26 PM »
Isn't that what we do here?

Yes it is.

Many of the known Block 5 changes seem to be in the category of bolt or engine changes.  I've wondered could a Block 3 or 4 essentially become a Block 5 with an engine change and the other bits added on?  (For example the FH side boosters.)

If not then I can see a limited life for any recovered Block 3 and 4 vehicles.  If Block 5's are significantly easier to refurbish it will likely be to expensive to do anything but re-fly the Block 5's.

As for Block 4, how many flights is that version going to have, 1 or 2?  Either the window for Block 4 is shrinking or the Block 5's are further away than we think.
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

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