SpaceX Falcon Heavy Discussion (Thread 6)

[Krankenhausen]

But if you think about it, they do have to have some confidence that it'd work to some extent right? I mean, it wouldn't be good if it went boom since 39A is sort off vital to commercial crew. Would they seriously risk that?

Have you ever heard of the concept of "managing expectations"? This is what Elon does. He routinely low-balls the chances of success whenever something new is tried for the first time. (and even after that too)

FH won't launch until SpaceX is very confident it will hold together enough to clear 39A and beyond.

Fair enough, than we have both come to more or less the same conclusion that they expect the launch to be successful at least to some extent. I was just a little concerned about them gambling 39A, but I'm sure they'll make an informed decision.

Thinking about it some more, the pad is likely not the most uncertain part of the flight (except it will just not launch if not all 27 engines start equally.) The most uncertain part is likely somewhat later in flight when significant aero forces start to come into play.

[Proponent]

But if you think about it, they do have to have some confidence that it'd work to some extent right? I mean, it wouldn't be good if it went boom since 39A is sort off vital to commercial crew. Would they seriously risk that?

Have you ever heard of the concept of "managing expectations"? This is what Elon does. He routinely low-balls the chances of success whenever something new is tried for the first time. (and even after that too)

FH won't launch until SpaceX is very confident it will hold together enough to clear 39A and beyond.

In the past, there's been a lot of nonsensical, in my view, commentary to the effect that the N-1, with its 30 first-stage engines was a disaster, and Falcon Heavy, with 27, isn't much better.  Though I still expect SpaceX to make a success of Falcon Heavy, reading that the nearly simultaneous ignition of all 27 engines will not be attempted until the first flight vehicle is on the pad does send a bit of a shiver down my spine.  It has often been said that the N-1's problems lay not in the sheer number of engines but in the lack of ground testing of the full engine cluster.

[Jet Black]

But if you think about it, they do have to have some confidence that it'd work to some extent right? I mean, it wouldn't be good if it went boom since 39A is sort off vital to commercial crew. Would they seriously risk that?

Have you ever heard of the concept of "managing expectations"? This is what Elon does. He routinely low-balls the chances of success whenever something new is tried for the first time. (and even after that too)

FH won't launch until SpaceX is very confident it will hold together enough to clear 39A and beyond.

Fair enough, than we have both have come to more or less the same conclusion that they expect the launch to be successful at least to some extent. I was just a little concerned about them gambling 39A, but I'm sure they'll make an informed decision.

Thinking about it some more, the pad is likely not the most uncertain part of the flight (except it will just not launch if not all 27 engines start equally.) The most uncertain part is likely somewhat later in flight when significant aero forces start to come into play.

tbh I doubt they would be gambling the pad since it's the same one that their commercial crew relies on and certainly I'd expect the FAA to not grant a licence to anything with as much doubt as he is expressing. I think he's just playing to the crowd to whip up a bit of excitement.

[old_sellsword]

So can anyone share a little bit about the development of Delta IV Heavy?

One thing we know about Delta IV is that it has, IIRC, four different versions of core:  single-stick medium core, heavy core, left booster core and right booster core.  That makes it more expensive than it ought to be.  The plan was for just three cores, with the heavy core flying as the medium core, but performance shortfalls meant that the medium core had to be lightened, making it a separate variant.  It sounds like the Falcon family has at most three cores, because the left and right heavy boosters are identical.

Eventually, the Falcon family will consist of only two booster types: Falcon Heavy center cores and Falcon Heavy side boosters that double as regular Falcon 9s.

These upcoming Block upgrades are putting a lot of work into increasing the commonality between F9 and FH, including things like the bolted octaweb.

[Jim]

So can anyone share a little bit about the development of Delta IV Heavy?

One thing we know about Delta IV is that it has, IIRC, four different versions of core:  single-stick medium core, heavy core, left booster core and right booster core.  That makes it more expensive than it ought to be.  The plan was for just three cores, with the heavy core flying as the medium core, but performance shortfalls meant that the medium core had to be lightened, making it a separate variant.  It sounds like the Falcon family has at most three cores, because the left and right heavy boosters are identical.

Atlas V Heavy would have had one type of core

[Jim]

tbh I doubt they would be gambling the pad since it's the same one that their commercial crew relies on and certainly I'd expect the FAA to not grant a licence to anything with as much doubt as he is expressing. I think he's just playing to the crowd to whip up a bit of excitement.

The FAA doesn't care as long as nobody will get hurt or no 3rd party property gets damaged.

[spacenut]

It seems to me, there are stresses, the outside cores have to put all their lift capability to the center core.  Center core has to take more stress, like 3 times as much.  Then after liftoff, the outer cores go full thrust while the center core throttles down.  Then there is the separation event.  Soyuz basically just falls out by gravity, and maybe a thruster to get the side boosters out of the way of the center.  No so with FH.  Then the side boosters have to come back and land without getting in each others way.  What they are doing is not easy. 

Seems to me if they are far enough along with BFR and ITS or BFS, they should put all their effort into those and get them going in a few years.  They will put FH out of business.  Single core, single big reusable spacecraft.  Anything can be launched to deep space or GSO with it. 

[Helodriver]

So can anyone share a little bit about the development of Delta IV Heavy?

One thing we know about Delta IV is that it has, IIRC, four different versions of core:  single-stick medium core, heavy core, left booster core and right booster core.  That makes it more expensive than it ought to be.  The plan was for just three cores, with the heavy core flying as the medium core, but performance shortfalls meant that the medium core had to be lightened, making it a separate variant.  It sounds like the Falcon family has at most three cores, because the left and right heavy boosters are identical.

Eventually, the Falcon family will consist of only two booster types: Falcon Heavy center cores and Falcon Heavy side boosters that double as regular Falcon 9s.

These upcoming Block upgrades are putting a lot of work into increasing the commonality between F9 and FH, including things like the bolted octaweb.

With the continuous improvement in thrust and efficiency of the Merlin engines, and given the opportunity to examine landed FH cores to see where the actual stress points are, its conceivable that a future FH iteration could be made of three near identical boosters, the only difference being the reconfigurable mounts. Side boosters and single stick F9s would be heavier but that could be offset by the enhanced engines and the structural robustness might translate into longer service lives.

This may be particularly attractive if BFR/ITS - mini is delayed in development.

[clongton]

It has often been said that the N-1's problems lay not in the sheer number of engines but in the lack of ground testing of the full engine cluster.

That and FOD. All four launches were a failure and it is know for certain that two of them were FOD related. Soviet Quality Control was practically nonexistent in their rocket manufacturing processes.

[wannamoonbase]

It has often been said that the N-1's problems lay not in the sheer number of engines but in the lack of ground testing of the full engine cluster.

That and FOD. All four launches were a failure and it is know for certain that two of them were FOD related. Soviet Quality Control was practically nonexistent in their rocket manufacturing processes.

There's an excellent book "The Secret of Apollo: Systems Management in American and European Space Programs" that explains systems management and how western cultures of being open and working together is just easier.  Because we think that way.

I wouldn't want to be Quality Control in the Soviet Union.  Being the person that raises your hand to say there is a problem is a great way to get a 1 way ticket to Siberia.

Regarding Musk's comments about the inaugural FH launch, I think a significant target audience for him is the SpaceX staff working on it.  Keep them motivated and fearful of failure.  I think they will be successful, but nothing is certain until the payload is in orbit (the boosters are on the ground and ASDS)

[abaddon]

With the continuous improvement in thrust and efficiency of the Merlin engines, and given the opportunity to examine landed FH cores to see where the actual stress points are, its conceivable that a future FH iteration could be made of three near identical boosters, the only difference being the reconfigurable mounts. Side boosters and single stick F9s would be heavier but that could be offset by the enhanced engines and the structural robustness might translate into longer service lives.

This may be particularly attractive if BFR/ITS - mini is delayed in development.

If reuse pans out as well as they hope it does, I don't really see how this makes sense.  It'd be better to focus on the second stage, either optimizing for production cost or getting them back, since that's what they will be making in job lots.  First stages will only be put out occasionally so having two types shouldn't be that big of a deal.  Given the projected low flight rate, SpaceX might only make a handful of FH cores during its entire run.

[gospacex]

It seems to me, there are stresses, the outside cores have to put all their lift capability to the center core.  Center core has to take more stress, like 3 times as much.  Then after liftoff, the outer cores go full thrust while the center core throttles down.  Then there is the separation event.  Soyuz basically just falls out by gravity, and maybe a thruster to get the side boosters out of the way of the center.  No so with FH.  Then the side boosters have to come back and land without getting in each others way.  What they are doing is not easy. 

Seems to me if they are far enough along with BFR and ITS or BFS, they should put all their effort into those and get them going in a few years.  They will put FH out of business.

Even if FH will no longer be needed, the knowledge how to do Heavy can be very useful in the future. BFR-H, anyone?

[BeamRider]

"What do we think the odds are that, doing it all over again, SpaceX would not attempt a tri-core launch vehicle?"

Very low. Shotwell is poo-pooing the market size too. At one time it probably looked safer to build upon F9 technology than to redesign completely. Probably would have to me too.

[wannamoonbase]

Even if FH will no longer be needed, the knowledge how to do Heavy can be very useful in the future. BFR-H, anyone?

Not me.

I think EM will prefer to go with oversized single stick boosters.  Way less operations and steps needed.  Likely easier to design and build too.

The lesson of FH maybe to avoid more than a single body.

The lessons of FH design and analysis and sharpening those skills may help the BFR.

I agree with abaddon above, that the number of FH's ever built could be quite low.  1-2, maybe 3 missions a year with reuseable cores for the next 5-10 years until a new gen vehicle is ready. 

I could see the amount of FH ever built being in the 5-10 range.

[guckyfan]

It seems to me, people are overvaluing the statements by Elon Musk about FH difficulties. I see them similar to what Tom Mueller said about developing the Merlin engine. Very hard to do, with lots of failures in the development phase. But the result is a cheap, reliable, robust engine.

So will FH be as well. Assuming the first flight goes well, they will have a reliable easy to stack cost efficient heavy lift vehicle.  I hope they will not have a failure on the first flight. But in any case they will learn a lot and do some adjustments and optimization, if only in control software.

It may go quite soon. But when it goes so will F9. A new generation will replace them both. Possibly FH first but F9 not much later.

[Kenp51d]

Even if FH will no longer be needed, the knowledge how to do Heavy can be very useful in the future. BFR-H, anyone?

Not me.

I think EM will prefer to go with oversized single stick boosters.  Way less operations and steps needed.  Likely easier to design and build too.

The lesson of FH maybe to avoid more than a single body.

The lessons of FH design and analysis and sharpening those skills may help the BFR.

I agree with abaddon above, that the number of FH's ever built could be quite low.  1-2, maybe 3 missions a year with reuseable cores for the next 5-10 years until a new gen vehicle is ready. 

I could see the amount of FH ever built being in the 5-10 range.

Particularly good bet for block 5 cores. Just don't see much need to make many more than 5-10 heavy cores.
Unless heavy becomes the go to for constellation launches. That could change the betting odds.

Sent from my XT1565 using Tapatalk

[Space Ghost 1962]

The advantage of the triple booster is largely to lower the cost of an interim payload size growth in the market.

The disadvantage is that it can amplify costs, as it does for DIVH.

Which then defeats the point of growing payload size.

In this case, should it evade the "DIVH cost trap", it's an interim vehicle that *might* allow payload growth, assuming adequate reliability/frequency/cost (which is assuming a lot).

(Note - DIVH *did achieve payload size growth*, because Vulcan/ACES is sized to cover DIVH payloads. It just didn't do so in a way that allowed anything beyond DIV/HU.)

So should FH be a fantastic success, it would likely accelerate the need for a non-clustered LV, as we see with Vulcan.

A clustered vehicle is always an interim approach.

And once you exceed certain SHLV sizes, it's far easier to just make the larger vehicle to avoid clusters.

[Jim Davis]

A clustered vehicle is always an interim approach.

The Soyuz and Proton launchers were surely more than interim approaches?

[sunbingfa]

So can anyone share a little bit about the development of Delta IV Heavy?

One thing we know about Delta IV is that it has, IIRC, four different versions of core:  single-stick medium core, heavy core, left booster core and right booster core.  That makes it more expensive than it ought to be.  The plan was for just three cores, with the heavy core flying as the medium core, but performance shortfalls meant that the medium core had to be lightened, making it a separate variant.  It sounds like the Falcon family has at most three cores, because the left and right heavy boosters are identical.

For Delta IV Heavy, even Left and Right booster are not the same?

[Lars-J]

A clustered vehicle is always an interim approach.

The Soyuz and Proton launchers were surely more than interim approaches?

Soyuz is clustered, Proton is not.

And Soyuz does not use identical 'cores', the center one is very different.