Questions, Falcon Heavy

Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


Alain Fournier

In article , says...

Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

Separately. The landing facility that SpaceX has built at Cape
Canaveral Air Force Base has multiple landing pads to support this.

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


I believe that the landing pads are all at former SLC-13. So I'd guess
fairly close, as in perhaps hundreds of yards apart.

https://en.wikipedia.org/wiki/Landing_Zone_1

This article has some drawings and artist's renditions.

http://www.universetoday.com/124013/spacex-launch-2/

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

Alain Fournier wrote:
Does anyone know how the two boosters of the Falcon Heavy are
supposed to come back and land? Are they to land separately or are
they to be attached and land together?

The two boosters are on either side of the core stage. To "attach"
them mid-flight for purposes of landing would seem extraordinarily
complicated. If they were attached to one another from the beginning,
perhaps they might be landed together, but that isn't the
configuration.

rick jones
--
Don't anthropomorphize computers. They hate that. - Anonymous
these opinions are mine, all mine; HPE might not want them anyway...
feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH...

On Feb/28/2016 5:10 PM, Jeff Findley wrote :
In article , says...

Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

Separately. The landing facility that SpaceX has built at Cape
Canaveral Air Force Base has multiple landing pads to support this.

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


I believe that the landing pads are all at former SLC-13. So I'd guess
fairly close, as in perhaps hundreds of yards apart.

Two of them landing at the same time few hundred meters apart will be
quite a thing to see.


Alain Fournier

In article , says...

On Feb/28/2016 5:10 PM, Jeff Findley wrote :
In article , says...

Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

Separately. The landing facility that SpaceX has built at Cape
Canaveral Air Force Base has multiple landing pads to support this.

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


I believe that the landing pads are all at former SLC-13. So I'd guess
fairly close, as in perhaps hundreds of yards apart.

Two of them landing at the same time few hundred meters apart will be
quite a thing to see.

I believe this happens from time to time at airports that have parallel
runways. A quick web search says:

"For simultaneous landings and takeoffs using VFR, the minimum
separation between centerlines of parallel runways is 700 feet
(213 m)."

So, there shouldn't be a huge problem doing this with a vertical landing
vehicle given enough distance between the landing pads.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On Mar/4/2016 10:57 PM, Jeff Findley wrote:
In article , says...

On Feb/28/2016 5:10 PM, Jeff Findley wrote :
In article , says...

Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

Separately. The landing facility that SpaceX has built at Cape
Canaveral Air Force Base has multiple landing pads to support this.

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


I believe that the landing pads are all at former SLC-13. So I'd guess
fairly close, as in perhaps hundreds of yards apart.

Two of them landing at the same time few hundred meters apart will be
quite a thing to see.

I believe this happens from time to time at airports that have parallel
runways. A quick web search says:

"For simultaneous landings and takeoffs using VFR, the minimum
separation between centerlines of parallel runways is 700 feet
(213 m)."

So, there shouldn't be a huge problem doing this with a vertical landing
vehicle given enough distance between the landing pads.

I agree. There shouldn't be any problem with that. I think it is cool to
see two planes land in parallel. I also think it is very cool to see
even a single SpaceX booster land vertically. When two of them will land
simultaneously, I will watch the video.


Alain Fournier

On Monday, February 29, 2016 at 10:23:40 AM UTC+13, Alain Fournier wrote:
Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


Alain Fournier

http://www.spacex.com/falcon-heavy

The Outboard Boosters separate and land separately when they are depleted of most of their propellant. They are equipped with a cross-feed feature that allows the central core to operate as a second stage, even though the engines are up and running at lift off!

The two boosters will land separately at nearly the same time.

This technology permits a Falcon-Super to be considered! This has FOUR ADDITIONAL Boosters with a cross feed similar to this layout;

https://www.scribd.com/doc/38432542/...lement-Staging

That could provide further benefit and increased payload. This would involve four boosters landing simultaneously downrange, in Florida, and two additional boosters landing further downrange in Australia. The core booster would land at the launch center.

On Sunday, March 6, 2016 at 1:38:35 PM UTC+13, William Mook wrote:
On Monday, February 29, 2016 at 10:23:40 AM UTC+13, Alain Fournier wrote:
Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


Alain Fournier

http://www.spacex.com/falcon-heavy

The Outboard Boosters separate and land separately when they are depleted of most of their propellant. They are equipped with a cross-feed feature that allows the central core to operate as a second stage, even though the engines are up and running at lift off!

The two boosters will land separately at nearly the same time.

This technology permits a Falcon-Super to be considered! This has FOUR ADDITIONAL Boosters with a cross feed similar to this layout;

https://www.scribd.com/doc/38432542/...lement-Staging

That could provide further benefit and increased payload. This would involve four boosters landing simultaneously downrange, in Florida, and two additional boosters landing further downrange in Australia. The core booster would land at the launch center after orbiting the Earth.

https://www.spaceflightnow.com/falcon9/001/f9guide.pdf

FALCON

TOW: 505,846 kg

Prop: 402,286 kg
Struc: 22,000 kg
u: 0.795
d-Vee: 4.330 km/sec

S2-TOW: 81,560 kg
Prop: 64,867 kg
Struc: 3,543 kg
u: 0.795
d-Vee: 4.870 km/sec

**Payload: 13,150 kg LEO** NOMINAL

GEO Maneuver

TOW: 16,693 kg
Propellant: 8,300 kg

**Payload 4,850 kg GEO** NOMINAL

u: 0.497
d-Vee 1.06 km/sec

FALCON HEAVY

Adding two outboard boosters with 3.5% densified propellant;

TOW: 1,432,965
Propellant: 832,732
Structu 44,000
u: 0.581
d-Vee: 2.463 kps

S2-TOW: 545,696
Propellant: 416,366
Structu 22,000
u: 0.763
d-Vee 4.420 kps (6.883 total)

S3-TOW: 121,410
Propellant: 64,867
u: 0.534
d-Vee: 2.346 kps (9.228 total)

Payload: 53,000 kg

FALCON SUPER (estimated performance)

TOW: 3,151,412 kg
Propellant: 1,609,144 kg
Structu 88,000 kg
u: 0.5106
d-Vee: 2.022

2-TOW: 1,454,268
Propellant: 804,572
Structu 44,000
u: 0.5532
d-Vee: 2.474 kps (4.496 total)

3-TOW: 605,696
Propellant: 402,286
Structu 22,000
u: 0.6642
d-Vee: 3.3500 kps (7.846 total)

4-TOW 181,410
Propellant: 64,867
u: 0.3575
d-Vee: 1.3584 kps (9.2042 total)

Payload: 113,000 kg

Adding another upper stage to the stack permits placing 41,000 kg into a Lunar Free Return Trajectory, or land 31,000 kg on Mars!

In article ,
says...

On Monday, February 29, 2016 at 10:23:40 AM UTC+13, Alain Fournier wrote:
Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


Alain Fournier

http://www.spacex.com/falcon-heavy

The Outboard Boosters separate and land separately when they are depleted of most of their propellant. They are equipped with a cross-feed feature that allows the central core to operate as a second stage, even though the engines are up and running at lift off!

The two boosters will land separately at nearly the same time.

This technology permits a Falcon-Super to be considered! This has FOUR ADDITIONAL Boosters with a cross feed similar to this layout;

https://www.scribd.com/doc/38432542/...lement-Staging

That could provide further benefit and increased payload. This would involve four boosters landing simultaneously downrange, in Florida, and two additional boosters landing further downrange in Australia. The core booster would land at the launch center.

Last I heard, SpaceX is dropping cross-feeding, at least in the short
term. Part of the reason for this is densifying propellant will give
them some of the performance that cross-feeding would have. But the
complexity of sub-cooling propellant is less than adding cross-feeding
to the stages.

On of the downsides to arbitrarily adding more boosters to the core is
that eventually you have to strengthen the core, which means you lose
commonality with the boosters, which drives up costs a bit.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On Monday, March 7, 2016 at 9:03:15 AM UTC+13, Jeff Findley wrote:
In article ,
says...

On Monday, February 29, 2016 at 10:23:40 AM UTC+13, Alain Fournier wrote:
Does anyone know how the two boosters of the Falcon Heavy are supposed
to come back and land? Are they to land separately or are they to be
attached and land together?

I thought it was to be separately but after thinking about it, I don't
know why I thought that and I can see several things that would favour
landing them together. Though I still think landing them separately is
the best option, it isn't so obvious.

If they are to be landed separately, how far apart will they land?


Alain Fournier

http://www.spacex.com/falcon-heavy

The Outboard Boosters separate and land separately when they are depleted of most of their propellant. They are equipped with a cross-feed feature that allows the central core to operate as a second stage, even though the engines are up and running at lift off!

The two boosters will land separately at nearly the same time.

This technology permits a Falcon-Super to be considered! This has FOUR ADDITIONAL Boosters with a cross feed similar to this layout;

https://www.scribd.com/doc/38432542/...lement-Staging

That could provide further benefit and increased payload. This would involve four boosters landing simultaneously downrange, in Florida, and two additional boosters landing further downrange in Australia. The core booster would land at the launch center.

Last I heard, SpaceX is dropping cross-feeding,

cite? reference? I looked for one and couldn't find it.


at least in the short
term. Part of the reason for this is densifying propellant will give
them some of the performance that cross-feeding would have. But the
complexity of sub-cooling propellant is less than adding cross-feeding
to the stages.

Here's a simplified description of 'asparagus staging' done in KSP

https://www.reddit.com/r/spacex/comm...uel_crossfeed/

While this is very simplified modelling, it does show the advantages of the concept. Real analysis involving calculus of variations analysis, come up with specific values for the cross-feed rates, thrusts, structures and so forth. The result is that the plumbing that the Falcon Heavy has uses propellant crossfeed which leaves the core booster two-thirds full of propellant at staging while enabling it to run all engines at full power during the initial ascent. This appears best for their configuration.

Compare this design to the Delta IV Heavy design. The Delta IV must throttle back its central engine after liftoff in order to conserve the central core's fuel for use after staging.

Compared to a traditional inline-stage design, the propellant crossfeed eliminates the "dead weight" of carrying inactive second-stage engines from launch to the first staging event, as well as removing the risk of those engines failing to ignite in flight. The added complexity of plumbing is nil compared to these other factors.

On of the downsides to arbitrarily adding more boosters to the core is
that eventually you have to strengthen the core,

If you'd care to famliarise yourself with the design SpaceX is using, you'd find that the core must carry the upper stages and payload anyway, while the strap-on boosters are lengthened, and carry extra fuel and hardware for recovery.

which means you lose
commonality with the boosters, which drives up costs a bit.

Yes, each strapon is custom designed to do its job well. You can't get away from that. This does drive up costs, but only marginally in a well designed system. Sort of like ordering your Ford Galaxy with the guage pack, air conditioning and FM radio and a four speed, instead of stock.

https://www.youtube.com/watch?v=V-BL7G5m98M

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.