Falcon Heavy - General Discussion

[chickensevil]

Ah yes, that was it. I knew I saw it somewhere. I just couldn't remember where.

The reason for the Falcon X or whatever they are going to call the Mars Transport Ship... BFR I think is the current term... will use the Raptor engine that is in development. The biggest reason toward going this route is it is a methane based rocket and guess what is readily available and easy to get on mars? It certainly ain't RP-1 (Kerosene). Know of any dead dinosaurs on Mars?

With reuse being a key goal, they will likely leave the Falcon Heavy for either expendable long range missions or mostly things going as far as the moon. The BFR will be able to re-fuel (ideally) on Mars and then lift off for the return trip. Obviously there is a LOT of logistics that will need to happen to get there, but there are other good reasons beyond that to switch to methane.

Anyway, that is why I think they won't go the route of adding more to the Falcon Heavy. The other bit is that it is likely going to be tough enough to get the two outboard boosters to properly move its fuel into the central booster so they get 100% fuel use while also burning 100% of the engines. This is why they are able to get such crazy amount of thrust on the FH in such a small package (the other bit being very well designed Merlin engines )

 

[rolosrevenge]

Know of any dead dinosaurs on Mars?

You may be surprised what we find when we get heavy equipment over there and start excavating.

 

[rabar10]

On a side note, SpaceX just used their 100th core. The FH will use 28 at a time. That's a whole lot all at once. It won't take them long to get to hundreds more at that rate...

You mean 100th Merlin 1D engine. Yes, they are going though them pretty quickly now "Core" usually means the entire first-stage piece with all it's engines, i.e. Falcon Heavy will have 3 cores.

View attachment 73262

"Asparagus staging" works well in theory, and in Kerbal Space Program, but it leaves out the complexity/cost/weight/reliability issues with implementing a very complex cross-feed system, where large amounts of fuel/oxidizer from one booster or core is transferred to another core, in-flight, so that the first/outer cores are emptied first and can be quickly jettisoned.

I believe SpaceX has stated that their first launch(es) of Falcon Heavy will be without cross-feed. They can throttle the center core engines down until the outer cores are jettisoned, which provides some but not all of the advantages of cross-feed. Then they can incrementally test/add the functionality over time, the same way they are incrementally adding first-stage reliability to Falcon 9.

 

[VolkerP]

I see problems of assembling,rolling out and putting vertical an "Aspargus" configuration.

 

[doug]

Anyone know how tall the hanger that they're building for it is?

Falcon Heavy rocket hangar rises at launch pad 39A | Spaceflight Now

 

[Rheazombi]

Someone on the SpaceX reddit claims 50-55 ft.

 

[doug]

I was wondering if it might have the option to come out vertical like the Shuttle did.

 

[rabar10]

I was wondering if it might have the option to come out vertical like the Shuttle did.

SpaceX has stuck with horizontal integration for everything thus far, where it rolls out to the pad on its side and is then rotated into place.

I can think of a few reasons to make this building taller than the one at LC-40 (existing SpaceX pad):
1. room for larger-diameter payload fairings for Heavy launches
2. room for heavier cranes to handle heavier payloads, or for potentially moving all 3 first-stage cores at once (?)
3. to account for the base of the rocket starting up the incline to the pad while the top of the rocket and payload are still inside the building -- don't know if it's that close to the start of the incline, but it looks like it from the pics...

 

[doug]

You mean 100th Merlin 1D engine. Yes, they are going though them pretty quickly now

SpaceX put out this Vine vid with the 100th Merlin:
Watch SpaceX's Vine "The 100th Merlin 1D rocket engine..."
[vine]OQTB6FK7ADV[/vine]

 

[HVM]

I would also say that they only use horizontal integration, and I would be wrong, it seems:

http://spaceflightnow.com/2015/02/25/falcon-heavy-rocket-hangar-rises-at-pad-39a/

"SpaceX plans to add payloads to the Falcon 9 and Falcon Heavy rockets at pad 39A while they stand upright, a shift in the company’s operations concept at other launch facilities."

 

[chickensevil]

It might be better in this case, depending on how the three cores are actually connected together. The current connection of stage 1 and stage 2 is quite strong because of how they are pieced together. I would imagine that there will be about 4 release points for the side cores and depending on other complexities they may not have the structural handling to withstand shifting frequently from horizontal to vertical.

That would, at least, be my very unscientific data on the subject.

 

[rabar10]

I would also say that they only use horizontal integration, and I would be wrong, it seems:

http://spaceflightnow.com/2015/02/25/falcon-heavy-rocket-hangar-rises-at-pad-39a/

"SpaceX plans to add payloads to the Falcon 9 and Falcon Heavy rockets at pad 39A while they stand upright, a shift in the company’s operations concept at other launch facilities."

Neat, thanks. Continuing from your quote above:

"At SpaceX’s current launch pads, technicians attach satellites and payload shrouds to rockets inside their hangars in a horizontal configuration.

The U.S. Air Force requires vertical payload integration for its most critical communications, navigation and spy satellites, a capability SpaceX will support once pad 39A is operational."

So it would seem to be a requirement of the payloads (satellites) that they not be mounted/transported horizontally. They must be planning on adding a crane to the fixed service structure out at the pad, then, to place the must-stay-vertically-aligned payload on top of the rocket once it's been rotated to vertical on the pad.

 

[bxr140]

So it would seem to be a requirement of the payloads (satellites) that they not be mounted/transported horizontally. They must be planning on adding a crane to the fixed service structure out at the pad, then, to place the must-stay-vertically-aligned payload on top of the rocket once it's been rotated to vertical on the pad.

Virtually if not every large space payload is integrated vertically to the flight adapter regardless of location. Some tilt before or after encapsulation for transportation to the launch vehicle while others stay vertical during that transport event. The tilting restriction could be structural (a wet spacecraft going to GTO can be twice the weight of a dry spacecraft), but the restriction can also be geometrical limits on the spacecraft's propulsion system. Prop guys can get uber paranoid about bubbles collecting in corners...

On the other topic, I'd guess that even the asparagus configuration will be assembled horizontal and verticalized on the pad. Angara 5 just did a something similar a few months ago, though they admittedly have a bit more room between their cores.

 

[glhs272]

Although the asparagus staging falcon rocket may be technically possible, by the time there are any payloads that would need it the BFR can be made ready. I believe spacex has made the determination that since the BFR is the rocket they ultimately need for their Mars ambitions "let's just get on with it" and go straight to BFR. Hence there decision to forgo a reusable upper stage for the F9R and FH.

 

[freds]

The vertical requirement can be simpler than that since the spacecraft has to have strength to launched. However not designed to be horizontal for long periods of time where it would bend/stretch/droop get out of alignment, etc.

 

[Ben W]

I believe SpaceX has stated that their first launch(es) of Falcon Heavy will be without cross-feed. They can throttle the center core engines down until the outer cores are jettisoned, which provides some but not all of the advantages of cross-feed. Then they can incrementally test/add the functionality over time, the same way they are incrementally adding first-stage reliability to Falcon 9.

The reason this works is that the rocket needs to be throttled down significantly to pass through Max-Q anyway, so they throttle down the center core and continuing to fire the outer cores at 100%. This also reduces the amount of fuel that will need to be cross-fed when that functionality is enabled. The 6-booster configuration doesn't benefit as much from this, and has its own trade-offs. The complexity of the cross-feed and aerodynamics may be showstopping. Apparently SpaceX has figured out that the 2-booster "Heavy" configuration is the sweet spot, and if you need more payload to LEO/GTO/Mars, just make the whole thing bigger. Can't wait for the Falcon XX Heavy!

 

[glhs272]

Apparently SpaceX has figured out that the 2-booster "Heavy" configuration is the sweet spot, and if you need more payload to LEO/GTO/Mars, just make the whole thing bigger. Can't wait for the Falcon XX Heavy!

The noises I hear from the spaceflight community are that the 2-Booster "heavy" configuration is a kludge, not a sweet spot when taking reusability into account. Considering the center core is seriously hauling a** by the time is done burning. Pretty much have to have the down range ocean barge to get any useful payload improvement over a standard F9. Far simpler to have a single core 2 stage rocket. Just scale up as needed, land at launch site. The only reason the heavy exists is because of the road transportation size limit from factory to launch facility limiting core size. Thus, until they can create the new combined manufacturing and launch facility, they heavy is the only way to lift more than the standard F9. Expect that all future rockets beyond the 3.6 meter diameter core will be of the single core variety.

 

[HVM]

The Falcon Heavy Test stand is finally ready, although it's first used for the Full Thrust F9 testing.

nasaspaceflight.com/2015/09/full-thrust-falcon-9-stage-testing-mcgregor/

 

[aronth5]

SpaceX Signs New Falcon Heavy Commercial Launch Contracts

http://www.spacex.com/press/2015/09/14/spacex-signs-new-commercial-launch-contracts

 

[Grendal]

The Falcon Heavy SpaceX page was updated yesterday. No more talk of a cross-feed.

At the bottom of the page it reflects payloads to certain places in the solar system: 30,000 lbs. to Mars. For fun they even have a payload to Pluto: 6400 lbs.