SpaceX Falcon Heavy Discussion (Thread 6)

[envy887]

Have to admit to some surprise that the Telstar 19 going up tonight is 7000 kg and larger than FH’s Arabsat 6. 

The FH seems to have less and less market, currently.  Which is a shame.

FH could give it a much better orbit for a not much higher price.

I've seen a few six hour 2nd stage coasts and firings now. Is the Falcon considered able to do direct GSO?

F9 can't with any reasonable payload, but FH likely could. Or it could at least provide a supersync insertion and more inclination reduction. F9 is probably going to sub-sync with a 7 tonne sat.

[Spudley]

Have to admit to some surprise that the Telstar 19 going up tonight is 7000 kg and larger than FH’s Arabsat 6. 

The FH seems to have less and less market, currently.  Which is a shame.

FH could give it a much better orbit for a not much higher price.

That may be true, but it would have delayed the launch by months.

[hkultala]

Have to admit to some surprise that the Telstar 19 going up tonight is 7000 kg and larger than FH’s Arabsat 6. 

The FH seems to have less and less market, currently.  Which is a shame.

FH could give it a much better orbit for a not much higher price.

I've seen a few six hour 2nd stage coasts and firings now. Is the Falcon considered able to do direct GSO?

F9 can't with any reasonable payload, but FH likely could. Or it could at least provide a supersync insertion and more inclination reduction. F9 is probably going to sub-sync with a 7 tonne sat.

Fully expendable F9 should be able to do about 5 tonnes to GSO, but with 1st stage barge landing only about 1.5 tonnes.

[speedevil]

I've seen a few six hour 2nd stage coasts and firings now. Is the Falcon considered able to do direct GSO?

Zeroth order analysis, if you have 55 tons to LEO, and a 5 ton second stage, with a ISP of 347s, going from 25N, you need around 2454+1761m/s to get from 200km to GEO.
Or 4215m/s.

Doing the rocket equation calculations leads to somewhere north of ten tons in GEO.

Some evaporation may happen, but this might be partially mitigated by timing the orbit so at least some of the ascent occurs in shadow, and perhaps even splitting up the burns into three parts at some efficiency cost, but not having to vent.
7 tons - very comfortably with a reasonable margin.

[daveklingler]

This article has been making the rounds.

https://www.teslarati.com/spacex-bfr-mars-landing-site-2020/

“A walk-on presentation was given by Paul Wooster of SpaceX which highlighted the recent successful test of the Falcon Heavy launch vehicle with its potentially very large payload capacity (100 metric tons).

I'm assuming that's a typo.

[QuantumG]

hehe, yeah. 140,700 lb to LEO!

[speedevil]

I'm assuming that's a typo.

FH is specified as 60 tons to LEO.
Nominal stage mass would be around 175 tons.
To get 100 tons to LEO would need a stage mass of around 300 tons, or a more or less doubling of S2s length.

Call it two and a half times.
This would give an initial acceleration of 3m/s^2, and a burn of six minutes or so.
I don't think this naively quite hits the atmosphere, but it will need the trajectory steepened so it won't.
Stretching S2 has been called 'the easiest thing' - but this is quite a stretch indeed.

[groundbound]

I'm assuming that's a typo.

FH is specified as 60 tons to LEO.
Nominal stage mass would be around 175 tons.
To get 100 tons to LEO would need a stage mass of around 300 tons, or a more or less doubling of S2s length.

Call it two and a half times.
This would give an initial acceleration of 3m/s^2, and a burn of six minutes or so.
I don't think this naively quite hits the atmosphere, but it will need the trajectory steepened so it won't.
Stretching S2 has been called 'the easiest thing' - but this is quite a stretch indeed.

Alternatively, the current FH can launch 100 tonnes to earth orbit for a large class of earth orbits that intersect the earth's surface not far downrange from the launch site.

[speedevil]

Alternatively, the current FH can launch 100 tonnes to earth orbit for a large class of earth orbits that intersect the earth's surface not far downrange from the launch site.

A great idea, then you just need to launch another FH, meet at 5km/s ballistically, ...

[envy887]

I'm assuming that's a typo.

FH is specified as 60 tons to LEO.
Nominal stage mass would be around 175 tons.
To get 100 tons to LEO would need a stage mass of around 300 tons, or a more or less doubling of S2s length.

Call it two and a half times.
This would give an initial acceleration of 3m/s^2, and a burn of six minutes or so.
I don't think this naively quite hits the atmosphere, but it will need the trajectory steepened so it won't.
Stretching S2 has been called 'the easiest thing' - but this is quite a stretch indeed.

Alternatively, the current FH can launch 100 tonnes to earth orbit for a large class of earth orbits that intersect the earth's surface not far downrange from the launch site.

Those types of "orbits" leave it in a condition similar to your username.

[Hominans Kosmos]

https://twitter.com/elonmusk/status/1023069021057380353

There have been some rumors that any Block 5 can be used as a Falcon Heavy center core? Is this true?

Replying to @nextspaceflight

Side boosters, yes, but too much load through center core

There was a bunch of rumors going on on reddit about the block 5 upgrade making F9 and Heavy side boosters interchangeable airframes with the center core, some even going so far as appealing to the authority of L2 knowledge. I would hope this journalist's curiosity and reconfirmation reply should put those misunderstandings at rest.

I wonder what the dry mass increase of the FH core booster would be like, and the resulting performance reduction if put to service as single stick or side booster. Considering that dry mass growth increases landing, re entry and boost back propellant budget.

[su27k]

SpaceX’s Falcon Heavy eyed by Europe/Japan as ULA nails spectacular Delta Heavy launch

The first payload considering Falcon Heavy for launch services is the Japanese Space Agency’s (JAXA) HTV-X, and upgraded version of a spacecraft the country developed to assist in resupplying the International Space Station (ISS). HTV-X is primarily being designed with an ISS-resupply role still at the forefront, but Russianspaceweb recently reported that JAXA is seriously considering the development of a variant of the robotic spacecraft dedicated to resupplying the Lunar Orbital Platform-Gateway (LOPG)

That impressive performance would also be needed for another LOPG payload, this time for ESA’s 5-6 ton European System Providing Refueling Infrastructure and Telecommunications (ESPRIT) lunar station module. That component is unlikely to reach launch readiness before 2024, but ESA is already considering Falcon Heavy (over its own Ariane 6 rocket) in order to save some of the module’s propellant. Weighing 6 metric tons at most, Falcon Heavy could most likely launch ESPRIT while still recovering all three of its booster stages.

[wannamoonbase]

I saw that story.  Wouldn’t that be an amazing launch, side boosters landing on the ASDS and expendable core.

That would be such a big win for SpaceX and help validate the expense of it’s development.

[envy887]

I don't see how Falcon Heavy would save propellant on the module compared to a Ariane 64. Either can easily send 6 t to TLI, and Falcon Heavy can do it with side boosters RTLS and core ASDS landings like the FH demo. But neither would be able to maneuver usefully after TLI to save any additional propellant - DHRO insertion will be done by the module with either launcher.

Unless they are only considering Ariane 62? That would put a 6 tonne payload in subsync GTO where it would need an additional ~800 m/s for TLI. That might make sense since FH is supposed to be priced between A62 and A64.

[speedevil]

I don't see how Falcon Heavy would save propellant on the module compared to a Ariane 64. Either can easily send 6 t to TLI, and Falcon Heavy can do it with side boosters RTLS and core ASDS landings like the FH demo. But neither would be able to maneuver usefully after TLI to save any additional propellant - DHRO insertion will be done by the module with either launcher.

At least the PPE element of the US module was supposed to launch with partially empty tanks.
If the module in question was also to launch with partially empty tanks for mass reasons on other launchers, but can launch full on FH, that could reasonably, with some reporting confusion end up as 'save some of the modules propellant'.

[Rik ISS-fan]

If ESA and JAXA was like the USAF or NASA they wouldn't be allowed to even consider launching payloads on Falcon Heavy. (Just so you realize how stupid US legislation is.)

[envy887]

If ESA and JAXA was like the USAF or NASA they wouldn't be allowed to even consider launching payloads on Falcon Heavy. (Just so you realize how stupid US legislation is.)

NASA launches payloads on European and Japanese and Russian rockets all the time.

ESA is not like the USAF. They don't have to consider national security at all.

[UKobserver]

It occurs to me that an elegant way to use the extra dV that FH provides, is to offer to launch even the heaviest GTO payloads into highly supersynchronous orbits, with quite a bit of inclination reduction included within the insertion burn, and then have S2 conduct it's deorbit burn as it hits apogee on that first orbit. The high apogee means that the absolute minimum propellant is required by S2 for that burn to lower perigee into the atmosphere and deorbit the stage.

The amount of inclination reduction chosen for the initial GTO insertion burn could be decided based upon where it was desired that S2 re-enter, to either hit a remote spot of ocean for safe disposal, or to target a designated landing zone for some sort of recovery. If different inclinations for the payload and S2 re-entry were desired, then a further inclination change could be conducted as part of the de-orbit burn at apogee.

That feels like a more elegant use of the dV to me, rather than expending it in circularising the orbit for a direct insertion of the payload into GEO, which would leave S2 either in a graveyard orbit, which isn't brilliant from a long-term stewardship perspective, or with a lot of work remaining if they desired it to be deorbited.

Is that how others envisage FH will be used, vis-a-vis GEO payloads? Or do you think we will start to see many direct GEO insertions? Or alternatively do you expect to see more and more of the dV difference between LEO and GEO being offloaded to the payload over time, as per recent launches, with FH simply delivering lots of fuel-laden payloads to LEO, for them to make their own way from there?

[speedevil]

That feels like a more elegant use of the dV to me, rather than expending it in circularising the orbit for a direct insertion of the payload into GEO, which would leave S2 either in a graveyard orbit, which isn't brilliant from a long-term stewardship perspective, or with a lot of work remaining if they desired it to be deorbited.

Direct deorbit from GEO needs some 1500m/s.
Near lunar impact takes 1km/s. (which may be delayed waiting for the moon to come around and the inclinations to line up).

Getting into an orbit where the perigee is raised over time by near encounters with the moon takes a hair less.

[Ekramer]

Is that how others envisage FH will be used, vis-a-vis GEO payloads? Or do you think we will start to see many direct GEO insertions? Or alternatively do you expect to see more and more of the dV difference between LEO and GEO being offloaded to the payload over time, as per recent launches, with FH simply delivering lots of fuel-laden payloads to LEO, for them to make their own way from there?

I have wondered about this also.  It seems satellite manufacturers have designed based on the capability/track record/cost of available launchers.  For whatever reasons, they are saying "thanks, but we will get from LEO to GEO ourselves".  Falcon Heavy changes the design parameters to allow the design of satellites which are more robust/redundant with more fuel for station keeping, and so have a longer service life.

If I am right, we should start seeing larger satellites with more fuel, but being launched by FH direct to GEO.  I am not sure the satellite operators gain anything from launch to supersynchronous orbit.  If the launch vehicle is capable and the risk/cost is similar, they would want the launcher to put the satellite exactly where it can start making money as soon as possible.  I think that is how FH will capture that market, getting a GEO satellite direct to its operating orbit immediately without the satellite expending time and fuel to get there itself.  And allowing the satellite manufacturers to build more robustly for a longer service life.