SpaceX, rapid reuse, and vertical rocket stacking (integration)

[Jcc]

I don't see a need to integrate the first and second stages vertically, if only the payload can't be rotated in gravity. Build a tower and swing arm gantry next to the pad, bring up the rocket on the TE and raise it, then integrate the encapsulated payload onto it. The tower is also needed for manned missions.

If you are thinking in terms of gas and go reusability, that will not happen with the current designs.

[meekGee]

1. That's about as far away from proof as can be.  It's a sort-of conjecture based on how EELVs are wired.

  EELVs are not reusable.  They don't have a fully capable avionics suit in the first stage, so are irrelevant.


For a reusable:

2.  Why would you pass all the high-bandwidth sense and control of 9 engines across the stage boundary, (complicating integration, adding failure modes) when there's a perfectly capable avionics package right there on the state, that is (wait for it) ALREADY CONNECTED to all 9 engines and can drive them on the way back home?

1.  wrong.  Titan Centaur had two guidance systems.  So did other ELV'

2.  I never said that, I said trajectory control.   Anyways, even in the booster that engine control and info doesn't go the guidance system, that is the job of an engine controller.  It just passes on engine health, thrust and  steering commands to and from the guidance system.

Info that is passed between stages.  engine status, stage status, avionics status, power status, range safety interconnects, stage breakwires, stage breakup indicators.

Doesn't matter.  You were saying that it's impossible to simplify stage integration because all of the high-bandwidth signals between them.

I'm telling if you have a reusable fly-back booster, you can treat it like a carrier vehicle, and only need very low bandwidth (status) communication between the two stages.

So you tell me about Titan?    In an expendable, the motivation to simplify all of this was secondary, since yeah, it's driven from the top.  It's a single rocket shedding parts.

Not so with a reusable rocket - there's a lot that can modified if you change your point of view, but you keep going back to how it works on Titans and such.

[llanitedave]

Another point to consider is that if SpaceX were planning for vertical integration, they'd be planning a VAB to support it.  I see no sign of that.  Even their proposed facilities at Brownsville show only a horizontal hanger.

Maybe you forgot, that they are trying to lease one of the shuttle pads. Where the rocket & payload, probably will be vertically installed. That is, unless the transporter platform, is not there. Then the rocket can be rolled to the pad & payload installed vertically, as needed. This pad could also, be used for crewed Dragon.

Why would they have different processing modes for different locations?  If they're horizontal at one, what good does it do them to go vertical at another?  They're trying to set up a single, predictable, repeatable system.

[Jcc]

What does it take to send "high bandwidth" data signals. A single fiber optic cable will give all the bandwidth you need, so make it 3 of them for redundancy.

[411rocket]

Why would they have different processing modes for different locations?  If they're horizontal at one, what good does it do them to go vertical at another?  They're trying to set up a single, predictable, repeatable system.

Apparently, some Govt payloads need to be installed vertically & it would also make sense, for crewed Dragon ops. In my view, the former Appolo / Shuttle pad, would be most likely, be their only vertical ops pad. But for now it is wait & see, if they get the 5 year lease, to that pad.

[Lobo]

Another point to consider is that if SpaceX were planning for vertical integration, they'd be planning a VAB to support it.  I see no sign of that.  Even their proposed facilities at Brownsville show only a horizontal hanger.

Maybe you forgot, that they are trying to lease one of the shuttle pads. Where the rocket & payload, probably will be vertically installed. That is, unless the transporter platform, is not there. Then the rocket can be rolled to the pad & payload installed vertically, as needed. This pad could also, be used for crewed Dragon.

Why would they have different processing modes for different locations?  If they're horizontal at one, what good does it do them to go vertical at another?  They're trying to set up a single, predictable, repeatable system.

If they were using pad 39A, they might -not- be able to do it the same as the old Titan pads because the old Titan pads are flat with a flame trench below the deck.  Where 39A has a raised pad with the flame trench on the deck.  So I'm not quite sure they could do it at 39A exactly like they have ad LC-40 and SLC-4.
And the only way I think they could try would be to build a HIV down on the deck, and then have an erector/transporter take the stack around a corner and into the bottom of the flame trench and erect it there.  Since the plume would come back out that side, the HIV couldn't be inline with it.  So there's a few issues there.
And as 411Rocket said, there appears to be DoD payloads that need to be integraded vertically.  That could be done with a crane or some sort of mobile gantry, but there's already hardware at 39A which could be used in the RSS and FSS.  I don't necessarily know if a crew Dragon would be beneficial to integrate vertically or not.  Cargo dragon doesn't need to be.  But, since it would be a -manned- spacecraft, I could see there being a need to access it on the pad for various checkouts and such prior to putting the crew on it.  This is where I could see the RSS being modified to make a LC-37 like MSS out of it.  D4 cores are loaded horizontally into the LC-37 MSS, and then rotated up vertically.  Once the single or 3 cores are vertical and the upper stage stacked on, the payload processing room closes around the top of the upper stage and the payload is integrated vertically.  When done, the doors open up and the MSS rolls back.
But on 39A, there already is a build RSS that does basically the same thing. It'd need to be rebuilt for a rocket instead of an orbiter, but the basical structure that rotates back and forth could be used I would think.
The FSS could be used for crew access.

Now, they could level the FSS, and RSS, and stick more with their conventional HIV, but I don't know if there's room for a HIV on the ramp side of the pad...and there's a flame trench on that side too.  So how do you get the horizontal stack over to the pad form that side?  You can put a flame divider off to that size so no flame actually comes out it and blows up the HIV, but there's still the big hole there you have to get over.  Saturn and Shuttle did it with a really big and side CT and MLP.    How would SpaceX do it?
And if they do do it, how do they integrate vertical payloads for DoD contracts?  They'd still need cranes and/or gantries. 

So it's a little different than the Titan pads they've used thus far.  So maybe they want to try to utilize the existing hardware as much as possible and integrate vertically with a payload integration room on a rebuilt RSS.  If they set the rocket down in the flame trench (as Jim suggested one time), they could then load the cores in through the trench side opposite the ramp.  Then the existing tower will be about the right height to access the upper stage and paylaod. 

[sugmullun]

It would seem to this layman:
  Vastly cheaper launches would be a watershed event, in a lot, if not most of the disciplines of the space industry. What is considered financially or technically necessary at the present time may well not be if the cost or difficulty of mitigating some issue could well be moved to another part of the "integration" of the package...even hardware-to-software or vice verse.
  While in the short term present engineering rules are rock solid. They are based very much on present technology and practicality.
  I think if one had to bet his/her life savings on which system, vertical or horizontal integration, past that watershed point, the best bet would be based purely on the financial considerations of the physical plant.  It almost seems impossible to predict whether it will be cheaper to have two independent entities cooperating in flight, or a master-slave relationship, or even if that consideration will have much effect on the cost. I only presume to have an opinion about this because in all of history, discovery or rapid technical advancement only fails to trump engineering discipline when the laws of nature are encountered.
  So...in my inexpert opinion, for at least the next couple of decades; 12 foot cores will be horizontal and larger ones will be vertical.
  Added: Trump is a poor choice of words, since engineering enables...., but it makes the point.
 

[AJW]

There are a number of crawler-cranes that with a 200' boom and counterweights could travel to a landing site, raise the core while the legs are stowed, and then lower the core onto a transport.  The cranes can't extend too far with significant weight, but many can carry twice the weight of an empty first stage which is a reasonable margin. 

What I don't know is whether a stage could be moved by the crawler while vertical, or if this can only be done with outriggers extended.  This might allow the crane to return the core to the strongback for lowering or reintegration & launching.

Another photo from McGregor and this one appears to show a mobile crane raising the core.

KISS

[Lobo]

There are a number of crawler-cranes that with a 200' boom and counterweights could travel to a landing site, raise the core while the legs are stowed, and then lower the core onto a transport.  The cranes can't extend too far with significant weight, but many can carry twice the weight of an empty first stage which is a reasonable margin. 

What I don't know is whether a stage could be moved by the crawler while vertical, or if this can only be done with outriggers extended.  This might allow the crane to return the core to the strongback for lowering or reintegration & launching.

Another photo from McGregor and this one appears to show a mobile crane raising the core.

KISS

Agreed.

As I worked through it in this thread, trying to helicopter it...even if there was a skycrane chopper that could do it...seems unnecessarily complicated compared to just having a crane pick it up slightly off the ground.  Retract the landing gear to the up postition, and then have some sort of carrier semi trailer to set it in horizontally for a nice slow drive back to LC-40 where it would slide horizontally back into the HIV (or perhaps a new building specifically for cores being reused prior to going into the HIV) and be ready to go again.
Assuming the F9 cores land at another pad not in use at the Cape like LC-36 or LC-46, it's not like they have to drive through any populated areas to get back to LC-40.

[RocketmanUS]

If on a MLP with a service tower could there be an elevator on the side of the service tower with an arm to lift up a fairing with the payload in it up to the top of the 2nd stage to be integrated to it?

[AJW]

There are a number of crawler-cranes that with a 200' boom and counterweights could travel to a landing site, raise the core while the legs are stowed, and then lower the core onto a transport.  The cranes can't extend too far with significant weight, but many can carry twice the weight of an empty first stage which is a reasonable margin. 

What I don't know is whether a stage could be moved by the crawler while vertical, or if this can only be done with outriggers extended.  This might allow the crane to return the core to the strongback for lowering or reintegration & launching.

https://twitter.com/elonmusk/status/413772104786780160/photo/1

Thanks, Elon.  Would you mind answering my question about what altitude the legs will be deployed at and if they are extended in one step or two?

[RanulfC]

2,  Yes, it would be very easy. .  The stage will be lighter.   A  strongback would be used for retrieval and break over.   It would be similar to the weapons systems TEL's, which handle heavier vehicles loaded with solid propellant.

The TEL's I've seen don't pick up a free-standing rocket. They just raise/lower between launch and transport positions.

TEL: Transporter/Erector/Launcher vehicle correct? They operate almost totally in the horizontal positon for several reasons most having to do with ease of access and storage of the weapon. However there are also TE trailers (Transport/Erectors) which are used to place and remove ICBMs from silos. An internal crane pulls the missile into the trailer where it is secured and then lowered to a horizontal position for transportation.

You're towing idea isn't very likely for several (mostly safety related) reasons but I'll give you the biggie right up front: Any "wind" at all (and there is a reason I put that in quotes) is going to cause increased stess' on the "down-wind" legs and through them to the dollies. Take your "example" tow concept, the "front" dolly/leg is going to be subjected to a "lifting" moment by the stage drag while under tow, meanwhile the "aft" (in your scenerio "free-wheeling) is going to be under increased "down-force" loads at the same time. This "assumes" a realtively "mild" tow speed of 15mph, your more likely tow speed of a high object like this is going to be 5mph or less. There is a very good REASON why anyone tries to avoid moving a vertical tall object if they can at all avoid it

And just and FYI you'd want to use a "Y" bar in any case and spread the "tow" load over two landing legs/dollies to increase control authority and distribute the stress in any case but again "towing" a "high" light objet with a low CG is asking for the majority of the "control" authority to be on the rear support wheels and not on the front/tow vehicle where it should be. Towing a booster around in a vertical position is just asking for an accident.

But the logic I'm following is:

First determine which orientation is preferred for first stage processing, since that's the majority of the work, and we're looking for RAPID reusabiilty.  From the reasons stated upthread, I think vertical is it.

I've read the whole thread and I think I "see" your reasoning but it is based on some false assumptions and what seems to me to be a lack of actual maintenance experiance for "rapid-reuse" items.

Vertical is used when you really have no other choice, it is much safer and easier to work on a "tall" object in a horizontal position because all of your work positions are then spead out instead of stacked on top of each other. Similarly "draining" becomes easier as all fluids are gravity fed to "one-side" where simple raising of the TE trailer gravity drains the fluids out the drain lines. Engine access is easy as a rolling "stand" system can give "level" access to each engine without having to "roll" the vehicle. (Your comment on the "RCS-crew" having to wait on the engine crew is an example of why I don't think your looking at this from a "maintenance" viewpoint. In a vertical position if an engine needs to be pulled or replaced or the engine bay opened up THEN the RCS crew along with every one else has to back off and wait on that operation to be finished because the rocket will have to be jacked up far enough to drop the engine and/or work ABOVE the inspection team will have to cease until they clear the area)

That last part is another reason NOT to work vertically "stacked": dropped tools and parts. If the RCS-crew drops a wrench in the vertical processing position everyone BELOW them is in danger as is the rocket itself from the wrench. (Falling further means more momentum and more impact energy at any point along the drop. We lost a Titan-II this way) Meanwhile in the horizontal position the furthest the tool/part can fall is a little over the stage diameter and the wrench dropped hits the floor sooner and not the engine inspection crew 70 some feet below.

Then look at the transport from the pad.  It will be IMO about 1 km, and the vehicle is already vertical. So I think it will travel that way.  Not having to handle tilt/untilit is an extra bonus here.

Travelling vertically calls for much lower speeds EVEN if the rocket is supported and stabilized on and in all axis'. A rocket on a TE trailer on the other hand is already supported in along all axis' and can be moved at much higher speeds from one point to another. The "extra" time for erection to vertical is trivial.

Distance from pads to processing: The main reason for distance is safety. An explosion on the pad can throw debris a long way, exploding in the air is worse and the debris travels farther. In the case of an RTLS reusable vehicle it will be "better" if the returning vehicle does not fly over any vehicle pads with ready or being prepared for launch vehicles. So there will be a seperation of landing and take off pads. (You'd want a pretty much "clear" flat pad to land on anyway) So your processing facility will be located between the two sets of pads. Since "berms" (earthwalls) only protect against debris/pressure from ground explosions the processing facility will also be located out from under any of the normal launch/return flight paths which will probably add some distance as well.

Lastly, look at 1st/2nd stage stacking.  Since I think inter-stage connections will be minimal-to-none, I don't see the difficulty in lift the 2nd stage on top, and then off to payload integration.

When "stacking" stages horizontally you only have to deal with left/right+forward/aft (4 direction but only two axis' of movement) as long as your assembly trailers are capable of fine up/down adjustment. All of these factors are easily done with minimum effort in a controlled environment such as an HIV. In a vertical (lifted) operation you have to worry about N/S/E/W+Up/Down (6 directions and at least 4 axis of direction) all at once during close operations. In addition you have to have a very high building unless you want to have to deal with complications due to wind activity, and high-bays are usually more expensive to build and maintain than low ones.

Even if the interstage connections were nothing but simple mechanical "locks" it is easier and faster to connect them horizontally rather than vertically.

As for picking up the landed stage at the pad, you'd back the TE into close position, raise the strongback and attach stabilizing cables to the booster. Raise the booster with a crane or jacks, fold the legs and then ease the booster into the TE cradle arms. Clamp and then lower to horizontal and off to the "barn" for processing.

I really can't stress the safety and operations factors that favor horizontal over vertical operations for high throughput enough. The main fact that several "crews" can be working at the same time on different parts of the vehicle without interference and in a safer manner than being "stacked" on top of each other is really a "killer" against vertical intergration. As long as rockets are going to be "tall-and-thin" horizontal is much safer and easier in every aspect and the "downside" of having to lower and then erect the vehicle is so small an effort it is simply a non-factor.

Now if we ever go to "shorter/squater" reusable first stages (always a possibility) then vertical servicing begins to make more "sense" in a lot of ways, but that does not seem to be the way SpaceX is going.

Randy

[Jim]

The TEL's I've seen don't pick up a free-standing rocket. They just raise/lower between launch and transport positions.

Free standing or sitting on the pad, no difference.
No different than picking up a rocket from the launch pad and returning it to a hangar for repair after a scrub

[meekGee]

The TEL's I've seen don't pick up a free-standing rocket. They just raise/lower between launch and transport positions.

Free standing or sitting on the pad, no difference.
No different than picking up a rocket from the launch pad and returning it to a hangar for repair after a scrub

That's a very inefficient way to design things.

The launch pad is holding the rocket using precision fiduciary points, and the TEL should register (dock) with them so that there's good alignment between the TEL and the rocket.   If that's not how it's done, that's too bad, but it still should be done that way.   (BTW do you know that there's no registration between the TEL and the pad at SpaceX?)

[Jim]

  (BTW do you know that there's no registration between the TEL and the pad at SpaceX?)

Spacex isn't the only TEL user, there is Antares and Delta IV.  The stage will be empty and light with no upperstage.   Backing up a TEL to the vehicle would be easy.  It would just have to engage one of the hold on points and have a similar gripper at the top like the current launcher.  After it engages the holdon and the gripper is in place, then it just has to take the load while the legs are retracted.  Once that is done, it can break over the vehicle for transport.  One hold down point should be adequate since the loads would be many times less without propellant and upperstage.

[Jim]

The launch pad is holding the rocket using precision fiduciary points,

No, it is not.  It is using the 4 holddown points, simple brackets with holes in it.

[meekGee]

That's what I mean.

There should be another set of mount points, whose relation to the "rocket brackets" is known, and to which the TEL docks.  Once you have that, there are no alignment issues between the TEL and the rocket, so you can haul it between the pad and the hanger quickly.

[llanitedave]

...snip great explanations...
I really can't stress the safety and operations factors that favor horizontal over vertical operations for high throughput enough. The main fact that several "crews" can be working at the same time on different parts of the vehicle without interference and in a safer manner than being "stacked" on top of each other is really a "killer" against vertical intergration. As long as rockets are going to be "tall-and-thin" horizontal is much safer and easier in every aspect and the "downside" of having to lower and then erect the vehicle is so small an effort it is simply a non-factor.

Now if we ever go to "shorter/squater" reusable first stages (always a possibility) then vertical servicing begins to make more "sense" in a lot of ways, but that does not seem to be the way SpaceX is going.

Randy

Best post in this thread so far.  Thanks!

[Jim]

Those were a given and obvious to most in the business

[Robotbeat]

If you could somehow eliminate (via automation) basically all the little tasks that workers need to do while integrating stages, it might make sense to do vertical stacking if you have a gas-and-go first stage (with pre-integrated upper stage and payload... perhaps themselves integrated horizontally).

A big question is when the launch rate will be high enough to support such a decision at all. Certainly not in the next five years and probably not in this decade, either.