Should SpaceX consider using SRBs on Falcon 9?

Oldfart1939 · 2017-08-01 12:52:48

The Falcon 9 has achieved a LOT as a 2 stage launch vehicle, both in the recoverable and expendable forms. But...many of the payloads they are now considering to GTO, there is a weight limit which has been reached for both forms of this system.

Elon Musk has made several statements recently regarding the long anticipated Falcon Heavy, and has been more cautionary than usual about the hoped-for success. GW has commented here that one of the major issues involved in the Falcon Heavy, is getting 27 engines to start in a reasonable amount of time without wrecking the whole thing. Yes, we've been hoping that this will be our ticket to Mars for the Red Dragon missions (now in jeopardy with the NASA complaint about the propulsive landings of Dragon 2, the man rated spacecraft).

I'm sure there has been other speculation about some sort of intermediate performance upgrade to enhance access to LEO, GTO, and beyond. SpaceX seems to have an institutional dislike and avoidance of using SRBs, which I believe is misguided.

I like to play with numbers and possibilities, so I am postulating how and what SpaceX could cobble together to improve the performance of their Falcon 9 which would enable heavier payloads to the desired orbits without expending 9 very pricey Merlin 1-D engines at some $3 million per copy, in addition to the airframe and associated avionics.

One obvious non-starter would be a collaboration between SpaceX and Orbital ATK, as they are competitors for the orbital resupply of the ISS. Additionally, Orbital is now providing the SRBs to ULA on the Atlas V series of boosters. This leaves just 2 other options: Aerojet General Rocketdyne, versus "in-house" construction.

My model uses the now abandoned AJ-60A, which could give a definite enhancement to the Falcon Full Thrust v.1.2.

Specifications (from Wikipedia):

Height: 17.0 meters (669 inches)
Diameter: 1.6 Meters (62 inches)

Gross mass: 46,697 kg (102,949 lb)
Thrust: 1,688.4 kN (379,600 lbf)
Burn time: 94 seconds

Approximate cost (each): $2.5 million

My proposal is based on the following reasoning: expenditure of 2 of these SRBs in order to recover a $40 million first stage of a Falcon 9 would certainly justify spending $5 million for them. Additionally, the additional thrust and burn time could be used advantageously to LEO for accumulation of components of a Mars spacecraft. But, why stop at 2 SRBs if getting to Mars is really on Elon's mind, or getting into the lunar return missions? The Falcon 9 is big enough to handle 4 strap-ons.

Performance numbers:

Falcon 9 v.1.2

Thrust: 7,607 kN (1,710,000 lbf)
Vehicle mass: 569,100 kg ( including payload to LEO, expendable form); Vehicle mass (dry): 50,700 kg (includes 22,800 kg payload).
Burn time for 1st stage: 162 seconds

Falcon 9 v.1.2 with 2 AJ-60A boosters

Thrust: 10,984 kN (2,469,200 lbf)
Vehicle mass: 662,494 kg (1,457,487 lb)

These numbers indicate the central core stage could be operated at ~80% thrust during the 93 seconds of SRB burn time, thus reserving sufficient fuel to allow the booster's recovery on the drone ship.

Another enhancement of this launch system would be an upgrade to the second stage through incoporation of the new Raptor engine burning LOX and CH4.

Just throwing this out for discussion...and more idle speculation.

Last edited by Oldfart1939 (2017-08-01 12:56:19)

RobertDyck · 2017-08-01 15:02:41

Better idea: restore propellant cross-feed. So that when side boosters drop off, the central core stage has full propellant tanks.

Oldfart1939 · 2017-08-01 15:35:32

Robert-

You misunderstand my basic thesis here; this is NOT a replacement for Falcon Heavy, but something of an upgrade for existing hardware. The Falcon Heavy has had issues, and I'm really hoping that it flies, and soon. What I'm suggesting is an upgrade which allows 100% opportunities for first stage recovery, instead of adding to the growing debris at the bottom of the Atlantic, as well as increased payload capacity to LEO.

Oldfart1939 wrote:

Elon Musk has made several statements recently regarding the long anticipated Falcon Heavy, and has been more cautionary than usual about the hoped-for success. GW has commented here that one of the major issues involved in the Falcon Heavy, is getting 27 engines to start in a reasonable amount of time without wrecking the whole thing. Yes, we've been hoping that this will be our ticket to Mars for the Red Dragon missions (now in jeopardy with the NASA complaint about the propulsive landings of Dragon 2, the man rated spacecraft).
I'm sure there has been other speculation about some sort of intermediate performance upgrade to enhance access to LEO, GTO, and beyond. SpaceX seems to have an institutional dislike and avoidance of using SRBs, which I believe is misguided.
I like to play with numbers and possibilities, so I am postulating how and what SpaceX could cobble together to improve the performance of their Falcon 9 which would enable heavier payloads to the desired orbits without expending 9 very pricey Merlin 1-D engines at some $3 million per copy, in addition to the airframe and associated avionics.

GW Johnson · 2017-08-01 15:41:37

Well, thanks to the US government aiding and abetting all forms of monopolization since WW2, Orbital ATK owns all the big-motor solid propellant houses. Aerojet-Rocketdyne is a liquid propulsion house, originally Rocketdyne in Canoga Park, CA, where the F-1's that pushed Saturn 5 were developed and produced. They were tested at Rocketdyne Santa Susannah, CA, before going to the NASA facilities in Huntsville, AL. Rocketdyne's old solid division was the plant in McGregor where I worked, which was a small motor house. Rocketdyne never, ever had a big-motor solid propellant house.

Before the McGregor plant closed, it was sold to Hercules Powder, then ATK long before the Orbital ATK merger. There were only 3 big-motor houses in the entire country. Two were located near Salt Lake City: Thiokol, and Hercules Powder across the valley from it. I've been there many times in the 1980's and early 1990's. I don't know if both facilities are still there, but at least one is. Orbital ATK owns them (or it). The third big motor facility was on the Mississippi river, originally run by the CSD division of United Technologies (UTC). That is now also an Orbital ATK facility.

The other solid propellant facilities run by Hercules Powder, Atlantic Research, and Aerojet, are all now Orbital ATK facilities. These were all small-motor (tactical) houses, not big-motor (strategic) houses.

The SRB's you describe can only come from a big-motor house. Orbital ATK owns them all.

GW

Last edited by GW Johnson (2017-08-01 15:42:40)

RobertDyck · 2017-08-01 16:04:55

Oldfart1939,

I understand; I just disagree. Falcon Heavy performance could be improved by restoring cross-feed. And it would be interesting to see what performance they could get with a Falcon 9 v1.1 core, and v1.2 (full thrust) side boosters, together with cross-feed. That was the original configuration of Falcon Heavy.

For even greater thrust, they could replace the core with subscale Raptor engines using LCH4/LOX, and replace the upper stage engine with a subscale Raptor vacuum engine also using LCH4/LOX. But stick with Falcon 9 v1.2 side boosters using RP1/LOX. Note: they tested Raptor with subscale engines at McGregor Texas in 2016, each produced 1 MN thrust. Merlin 1D produces 420 kN thrust at sea level, 480 kN thrust in vacuum. So I'm suggesting the same engines they already tested. The core stage could use 9 subscale Raptor engines, or 3 full-size Raptor engines. The upper stage should definitely use a single subscale vacuum Raptor.

Oldfart1939 · 2017-08-01 16:52:44

Robert-

I agree that the cross-feed should be used, but not until we have a successful launch of a Falcon Heavy--or 3!

GW- I never went further with my suggestion, but the way in which SpaceX operates, maybe they could buy a license to produce the desired SRBs from Orbital? If not, Musk has never shied away from the ab initio approach on anything. Who knows? Maybe they could get the o-ring situation corrected as you have many times stated!

SpaceNut · 2017-08-01 17:24:16

I agree that a triple barrel rocket with reduced engine count that is cross fed is the way to go but usually from that design the central core is of a greater length to allow for the seperation issues of going with recovery modes for the side and center unit. Current only get the sizing and not the recovery by Boeing with lockheed still just a paper rocket for the design.

Families with the strap on SRB's used for more mass further from LEO.

http://www.ulalaunch.com/products_atlasv.aspx

Solid Rocket Boosters
When missions demand additional thrust at liftoff, Atlas integrates up to three solid rocket boosters (SRB) on the Atlas V 400 series launch vehicle and up to five SRBs on the Atlas V 500 series vehicles. The Atlas SRB, manufactured by Aerojet, uses the world’s largest monolithic filament-wound carbon composite case.
Peak Vacuum Thrust: 380,000 lbf
Specific Impulse: 279.3 seconds
Length: 787 in
Maximum Diameter: 62.2 in
Weight: 102,950 lbs
Nominal Burn Time: 88.3 seconds
Performance
401(0SR)    431(3SRB) 551(5SRB)
GTO    4,750 kg 7,700 kg 8,900 kg
10,470 lbs 16,970 lbs 19,620 lbs
LEO    9,800 kg 15,260 kg 18,850 kg
Reference 21,600 lbs 33,660 lbs 41,570 lbs
GTO (Geosynchronous Transfer Orbit)=35,756 km x 185 km at 27.0 deg LEO-Reference (Low Earth Orbit-Reference) =200 km circular at 28.7 deg

https://en.wikipedia.org/wiki/Delta_(rocket_family)

Delta IV (9000-series) Medium+ models have two or four GEM-60 60-inch diameter solid boosters.

I do feel that a quick upgrade for payload for the Falcon 9 would be to add boosters as needed.

RobertDyck · 2017-08-01 22:24:24

SpaceNut wrote:

I agree that a triple barrel rocket with reduced engine count that is cross fed is the way to go but usually from that design the central core is of a greater length to allow for the seperation issues of going with recovery modes for the side and center unit.

The original design used a shorter central core stage, but the upper stage stacked on top. Total height of the centre was greater.
SpaceX: Falcon Heavy
Scroll down, you can click "INSIDE THE INTERSTAGE". Before the announcement...

After the announcement that all core stages will be the same...

Of course my suggestion for an upgrade would use LCH4 in the central core stage, RP1 in side boosters. That means cross-feed would not work. Of course an even greater upgrade would use LCH4 in all core stages.

SpaceX needs more flexibility to suit customer needs. Every time their engineers come up with options, their president Gwynne Shotwell wants to cut it down to just one. She's the one who decided to use v1.2 for all core stages. My suggestion would have 2 models of core stage, and 2 upper stages. You could mix-and-match for various configurations. But Gwynne would have to accept having that many models.

Oldfart1939 · 2017-08-02 07:44:34

This Shotwell approach is for economic rationalization. It's sort of high-tech "one size fits all." Except that it doesn't. As I've said in the past, there needs be an intermediate development rocket built, and my choice for such would be the Falcon X. What I've suggested in this thread is something of a stop-gap program which keeps pushing heavier and yet heavier loads to LEO. It would also serve as a backup plan, should the Falcon Heavy encounter yet more teething issues and subsequent delays. There's just so much space on the assembly lines in Hawthorne, and limited technicians to do the construction. Given the launch manifest, SpaceX needs to keep on building the Falcon v.1.2s for a long time to come.
This was obviously a "bean-counter" decision, not the best scientific/engineering solution, but...was also reality based.

GW Johnson · 2017-08-04 10:08:09

One of the very practical problems Spacex faced at its factory in California was too many different items on the production line. Keeping track of all this was eating up too much time and effort, which translated directly into schedule slips. That is why Shotwell simplified the list of configurations to be produced. Without this, they would not have gotten to where they are this soon. Simple as that.

This does have definite impacts on how things fit together, such as propellant cross-feed on Falcon-Heavy, or the lack of it. This is inevitable. It's part of the trade-off. Calendar schedule was more important overall, which is why they went the way they went.

Troubles with the capsule (such as not doing the propulsive landings) trace to bungling interference from a stodgy NASA. If Musk were developing crew Dragon on his own nickel, it would already be flying with men, and it would be landing propulsively. But Musk got this funded through NASA so he would not have to spend his own nickel. THAT is why crew Dragon has yet to fly.

Stodgy old NASA simply cannot bring itself to believe that "Not-ULA" can fly men safely, and cannot bring itself to believe in propulsive landings, despite what is in front of them from both Spacex and Blue Origin. Plus, they desperately do not want Boeing and Lockheed publicly embarrassed by "Not-ULA" flying first. That would also embarrass NASA itself, since these are its favorite go-to contractors. Even when it is so obvious there are better suppliers up-and-coming now.

Saving face is not exclusively a peculiar oriental culture item.

GW

Last edited by GW Johnson (2017-08-04 10:10:39)

Oldfart1939 · 2017-08-04 11:39:30

GW-

Thanks for the very good summary of "why things are the way they are." My basic thesis in starting this topic was an economic boost to "Getting Our Asses to Mars."

My observation of recent SpaceX missions, wherein the first stage boosters were determined to be "expendable," mainly as a consequence of consuming all onboard propellants to achieve the desired satellite in orbit, triggered my thinking about a cheaper albeit less elegant solution to the problem. If 2 SRBs cost $5 million, and the value of a recovered first stage is $40 million, (I've seen different numbers bandied about), then "expending" $5 million in order to recover $40 million hardware simply makes bean-counter sense. The reinforced central cores being developed for Falcon Heavy are probably even pricier than $40 million, but would be compatible with my suggested "Falcon Intermediate" concept.

None of us have an inkling to what goes on behind the closed doors of SpaceX headquarters, but since Aerojet had a SRB facility at McGregor, TX, and SpaceX has their live-fire testing facility there, perhaps they should consider acquisition of the old Aerojet facility?

Last edited by Oldfart1939 (2017-08-04 11:47:34)

SpaceNut · 2017-08-04 16:30:39

Not sure what buying the srb facility would really gain when its the mix of assemblies that seem to be the issue as that while not being in the same location buiding line does mean management must spread out to be able to keep all parts of build working. Just modify the attachment location and buy what you need would seem to be the way to go to keep it simple for build and launch use.

The ULA monopoly of boeing and lockheed was a means to drive costs down and not so much to simplify production.

GW maybe it is time for some egg on the faces of the not from ula and even a manned dreamchaser would do that....

Oldfart1939 · 2017-08-04 17:26:43

SpaceNut. In the case of Falcon Heavy, the 3 booster cores will of necessity be assembled at KSC. I was speculating that the individual SRBs could be developed and a lot sample test fired in Texas. A test integration could be done there as well.

GW Johnson · 2017-08-04 19:23:01

Actually, I quite agree with Oldfart1939 that adding SRB's to a Falcon-9 core could make feasible recovery and reuse when otherwise the choices would be fully-expendible or the next bigger launcher.

The problem is that it is competitor Orbital ATK that owns all the still-existing big-motor facilities for making SRB's. A part of Spacex's low price strategy is making stuff in-house to the greatest extent possible. To do this SRB thing, they would need to build such a facility, and learn the solid rocket engineering art.

The old McGregor plant where Spacex tests liquids now never belonged to Aerojet and never made SRB-sized motors. All the old solid propellant equipment was scrapped when it closed in 1996. Most of the people who knew the art have either died are are retired so long now as to be no longer useful.

Spacex cannot build such a facility in Hawthorne, where the public is all around them. They cannot fire a liquid there, for safety reasons, and solids are much more dangerous. The only real choices for them would be to build a facility from scratch at either McGregor or Brownsville. Actually, the public is too close at Brownsville, and that will "bite" them when they fly something larger than Falcon-Heavy from that site. It'll cause an international incident, too, since about half the proximate public is in Mexico.

To do it at McGregor, they would need the entire 10,000 acres of the old plant (of which they have a tiny fraction). And the test stands are quite different. Solids destroy the kind of flame tunnel installations they are using for noise control, and also the kind of steel tower stand they inherited from Andy Beal.

But I don't see them turning to competitor Orbital ATK to buy what they need. That's rather a hostile situation. And not conducive to lower prices.

GW

PS - the sequence of owners at McGregor was US gov't, then Phillips Petroleum, then on its own as Astrodyne, then the solid division of Rocketdyne/Rockwell International, then Hercules Powder, then ATK as Alliant Techsystems briefly, long before the merger with Orbital, then it was closed and given to the City of McGregor. After a long struggle cleaning up the various environmental messes.

Last edited by GW Johnson (2017-08-04 19:31:41)

Oldfart1939 · 2017-08-05 12:45:27

SpaceX seems to have in one sense, boxed themselves in by taking over the old Northrup plant in Hawthorne? The statements from the management about transportation of vehicles larger than 3.7 meters diameter (12 feet) due to bridge and tunnel sizes is undoubtedly valid. Maybe they should consider doing what Blue Origin has begun, and build a manufacturing facility closer to KSC? In Texas, there are few tunnels to worry about. Getting somewhere where barge transportation is possible would work.

For a business, buying up the entire 10,000 acres in Texas would certainly be a lot less expensive than trying to build a new plant in any metropolitan area. Even at $1,000 an acre, that's still only $10 million. The Aerojet AJ60-A hasn't been that long out of production, and I'd venture there are still a few engineers around that could either reproduce it or build a modernized and improved version thereof.

This idle speculation raises another question: where is the ITS going to be built--if ever? Certainly not in Hawthorne, CA!

RobertDyck · 2017-08-05 14:51:30

I still disagree. If SpaceX is willing to consider a different model stage, they could build a stage the same size as Falcon 9 core stage but with LCH4/LOX and Raptor engines. They already tested subscale engines, so this is not a radical step for them. And since Elon intends to build MCT/ITS using Raptors, this would be an intermediate step between what they have now and MCT/ITS.

Oldfart1939 · 2017-08-05 15:32:14

Robert-

You and I have separately made the suggestion for an "Improved Falcon 9," using a single Raptor in the second stage. Maybe that's what Elon has up his sleeve for us mere mortals? The vacuum Isp has been stated at 383 seconds, which is about 20% better than RP-1 and LOX.

Getting the highest mass into orbit is the "name of the game." Yes, I have great hopes for Falcon Heavy v.1.0, but there's a lot of development still needed before it becomes man-rated.

Recent announcements from Orbital ATK seem to indicate that SpaceX has cornered the market for commercial satellite launches, and they (Orbital) are focusing on feeding at the government trough.

Oldfart1939 · 2017-08-06 09:30:57

Even with the Falcon Heavy, exists the possibility of adding SRBs to upgrade performance. The core stage has two stations available for a couple big SRBs, and both the booster stages could accommodate 1,2, or even 3 apiece. This could become overly complicated and unwieldy, however. Getting everything to ignite in milliseconds--or not--could be catastrophic.

I would state that the successes of the ULA Atlas V can be attributed to using the SRBs. Any disputation there, or other comments?

Based on my comments in post #17 above, and the fact that Orbital may be facing "leaner times," wondering out loud as to whether they would consider selling SpaceX a license to manufacture the AJ60-A boosters? That, or sell the technology outright?

SpaceNut · 2017-08-06 10:36:12

The AJ60-A booster motor is configured with a thrust profile that reduces aerodynamic loads during max-Q and thrust-differential during tail-off. It can be configured for other applications that require a different case length and/or attach interface requirement. It could also be used as an in-line stage for small launch vehicles or strategic missiles. Orbital ATK beats out Aerojet in ULA booster selection

United Launch Alliance has selected Orbital ATK to provide solid rocket boosters for the company’s next-generation Vulcan launcher, and will switch the workhorse Atlas 5 to the new booster supplier by the end of 2018, officials said Tuesday. Boeing officials confirmed reports earlier this month that Aerojet Rocketdyne attempted to buy ULA. A Boeing spokesperson said Sept. 16 the unsolicited bid, reportedly worth $2 billion, was “not something we seriously entertained for a number of reasons.” The new Orbital ATK-made boosters are 63 inches in diameter and approximately the same 67-foot height as the Aerojet motors, according to Jason Meredith, the GEM-63 and GEM-63XL program manager at Orbital ATK.
The boosters are slightly wider than the 60-inch diameter motors Orbital ATK produces for ULA’s Delta 4 rocket line. Earlier motors in Orbital ATK’s graphite epoxy motor, or GEM, series include smaller boosters for the Delta 2 rocket.
The Atlas 5 rocket has flown with 72 of the Aerojet-made AJ-60A motors in its 56 flights since 2002. The AJ-60A motors generate an average 280,000 pounds of thrust during their 90-second burn.

Oldfart1939 · 2017-08-07 08:20:02

After a visit to the Aerojet-Rocketdyne web page, it appears that they still are willing to sell the AJ60-A motors. It could be that they could conceivably be persuaded to enter into a joint venture with SpaceX? Just some speculativel thoughts.

Last edited by Oldfart1939 (2017-08-07 08:20:54)

elderflower · 2017-08-07 08:33:30

Does Musk do joint ventures? I wouldn't if I were in his position.

Oldfart1939 · 2017-08-07 09:04:49

I don't think he does, either. He could conceivably buy the SRB segment of AJ-Rocketdyne. He certainly has the $$$. Net worth $21.3 Billion.

elderflower · 2017-08-07 09:17:10

And sub-contracted or in house jobs are much easier to manage. JVs always seem to get political.

GW Johnson · 2017-08-08 10:12:26

Well, let's arbitrarily say it takes 8 AJ60's to do what two liquid boosters could do on Falcon-Heavy. These solids are around $5-6 M each as expendable items. They also contain less total impulse than the liquid boosters: burn time 90 versus 200+ sec. Just wild-guess numbers here.

Now suppose you can refurbish and refly the side boosters (and core) for, say, $20-30M for the pair. Let's also say arbitrarily you can do this 5 times before you have to buy new ones for about $80 M for the pair.

In both cases, there's another $20-30M for the second stage and launch costs.

What do 10 flights cost? For the liquids, two new sets for $160M and 8 refurbishments for $160-240M. Plus $200-300M for the second stages and launch costs. That's $520-$700M for 10 flights, or $52-70M per flight. The all-expendible price is about $100-120M. Not too bad a crude estimate.

Now for the solids: $40-48M per flight for solids, plus $20-30M per flight for second stages and launch costs, plus two $40M new cores and eight $10-15M core refurbishments. That totals up $400-480M for solids, $200-300M for second stages, $80M for the two new cores, and $80-120M for core refurbishments. That's $760-960M for 10 flights, or $76-96M per flight.

You can save money with expendible solid boosters and refurbished cores, but not quite as much as if you re-flew and refurbished liquid boosters as well.

So, what that really says, if you want to fly a payload heavy enough to preclude booster and core recovery, then adding a couple of solids to enable recovery would be a smart move. It costs more, but less than all-expendible.

The enabler to do this is structural: is the core strong enough to hang onto all this added thrust? It probably isn't right now.

In a related thought: if I were Musk, I would be asking Shotwell to consider a new second stage using the Raptor engine. Longer, but about the same weight, and much more thrust at higher Isp. A crude intuitive guess is that it might double payload. How about 100 tons instead of 50 tons to LEO? Beat SLS to the punch?

GW

Oldfart1939 · 2017-08-08 14:41:13

GW Johnson wrote:

In a related thought: if I were Musk, I would be asking Shotwell to consider a new second stage using the Raptor engine. Longer, but about the same weight, and much more thrust at higher Isp. A crude intuitive guess is that it might double payload. How about 100 tons instead of 50 tons to LEO? Beat SLS to the punch?
GW

Well, this makes it unanimous! I made this suggestion in post #1, and Robert reiterated it in post #5.

To me this also allows SpaceX the opportunity to fly the new hardware at a lower risk of failure; launch one of the new upper stages with CH4 and LOX using a previously flown first stage, and make it a throwaway or even a first stage recovery.

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#1 2017-08-01 12:52:48

Should SpaceX consider using SRBs on Falcon 9?

#2 2017-08-01 15:02:41

Re: Should SpaceX consider using SRBs on Falcon 9?

#3 2017-08-01 15:35:32

Re: Should SpaceX consider using SRBs on Falcon 9?

#4 2017-08-01 15:41:37

Re: Should SpaceX consider using SRBs on Falcon 9?

#5 2017-08-01 16:04:55

Re: Should SpaceX consider using SRBs on Falcon 9?

#6 2017-08-01 16:52:44

Re: Should SpaceX consider using SRBs on Falcon 9?

#7 2017-08-01 17:24:16

Re: Should SpaceX consider using SRBs on Falcon 9?

#8 2017-08-01 22:24:24

Re: Should SpaceX consider using SRBs on Falcon 9?

#9 2017-08-02 07:44:34

Re: Should SpaceX consider using SRBs on Falcon 9?

#10 2017-08-04 10:08:09

Re: Should SpaceX consider using SRBs on Falcon 9?

#11 2017-08-04 11:39:30

Re: Should SpaceX consider using SRBs on Falcon 9?

#12 2017-08-04 16:30:39

Re: Should SpaceX consider using SRBs on Falcon 9?

#13 2017-08-04 17:26:43

Re: Should SpaceX consider using SRBs on Falcon 9?

#14 2017-08-04 19:23:01

Re: Should SpaceX consider using SRBs on Falcon 9?

#15 2017-08-05 12:45:27

Re: Should SpaceX consider using SRBs on Falcon 9?

#16 2017-08-05 14:51:30

Re: Should SpaceX consider using SRBs on Falcon 9?

#17 2017-08-05 15:32:14

Re: Should SpaceX consider using SRBs on Falcon 9?

#18 2017-08-06 09:30:57

Re: Should SpaceX consider using SRBs on Falcon 9?

#19 2017-08-06 10:36:12

Re: Should SpaceX consider using SRBs on Falcon 9?

#20 2017-08-07 08:20:02

Re: Should SpaceX consider using SRBs on Falcon 9?

#21 2017-08-07 08:33:30

Re: Should SpaceX consider using SRBs on Falcon 9?

#22 2017-08-07 09:04:49

Re: Should SpaceX consider using SRBs on Falcon 9?

#23 2017-08-07 09:17:10

Re: Should SpaceX consider using SRBs on Falcon 9?

#24 2017-08-08 10:12:26

Re: Should SpaceX consider using SRBs on Falcon 9?

#25 2017-08-08 14:41:13

Re: Should SpaceX consider using SRBs on Falcon 9?

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