Author Topic: SpaceX Falcon Heavy Discussion (Thread 6) (Read 551535 times)

Johnnyhinbos · « **Reply #460 on:** 02/04/2018 03:03 pm »

And as far as I see it at least, with the restriction of fairing size (length / diameter) the large boost performance of FH to LEO is also marginalized. I feel FH, beyond the proof of concept flights, needs a change in some aspect to realize it’s true potential - and at this, uh, stage in SpaceX’s plans moving forward I don’t see that happening. Personally I see FH as the b*stard stepchild in the Falcon family (and I’ll use ‘Falcon’ in BFR in this context, even though that’s not the word Elon was thinking about).

However, it’s still amazing and a beast. My guess is even though it’ll never really be flown to its potential, it’ll STILL fly more times then the SLS...

Robotbeat · « **Reply #461 on:** 02/04/2018 03:05 pm »

For trans Mars insertion, c3=14km^2/s^2, FH beats Delta IV Heavy and Atlas V handily, all without a kick stage. And that's using elvperf.ksc.nasa.gov which is out of date for FH figures.

Robotbeat · « **Reply #462 on:** 02/04/2018 03:10 pm »

I checked again on elvperf.ksc.nasa.gov and the highest energy trajectory for which there is data for FH and Atlas V is c3=60 km2/s2, and FH still beats the heaviest configuration of Atlas V. And this website is using older performance figures for FH.

Jim is incorrect. Do I get a piece of candy? 😂

dglow · « **Reply #463 on:** 02/04/2018 03:13 pm »

Svetoslav · « **Reply #464 on:** 02/04/2018 03:17 pm »

As for lunar trajectories, can FH send a Dragon 2 directly to the Moon?

Ictogan · « **Reply #465 on:** 02/04/2018 04:23 pm »

Quote from: Svetoslav on 02/04/2018 03:17 pm

As for lunar trajectories, can FH send a Dragon 2 directly to the Moon?

FH has a listed payload capability to Mars of 16.8 tons, Dragon 2 is quite a bit lighter than that and going to the Moon requires some less delta-V than going to Mars, so that won't be a problem.

docmordrid · « **Reply #466 on:** 02/04/2018 05:32 pm »

Quote from: Svetoslav on 02/04/2018 03:17 pm

As for lunar trajectories, can FH send a Dragon 2 directly to the Moon?

https://forum.nasaspaceflight.com/index.php?topic=42421.0

AbuSimbel · « **Reply #467 on:** 02/04/2018 05:37 pm »

A question: based on the performance figures on the NLS-II website, wouldn't the 3500kg to Pluto listed on FH official page be impossible?

Lar · « **Reply #468 on:** 02/04/2018 05:55 pm »

Quote from: octavo on 02/04/2018 02:15 pm

Quote from: Svetoslav on 02/04/2018 02:06 pm
Never mind, I found a way to read the discussion.

Do I get it right? Falcon Heavy doesn't have an efficient upper stage and that's why the rocket is inferior to other expendable rockets when it comes to interplanetary missions?
Yep.

It's a valid criticism, as far as it goes. Requests for candy notwithstanding.

But it's mostly irrelevant, and can be mitigated. GSE can be changed. SpaceX does it all the time. Cuts into payload height as the fineness ratio can't be pushed much but a third stage doesn't have to be that tall. IMHO.

Also, I don't think Jim gives out candy. Someone could ask him monday night...

groundbound · « **Reply #469 on:** 02/04/2018 06:05 pm »

Quote from: Svetoslav on 02/04/2018 03:17 pm

As for lunar trajectories, can FH send a Dragon 2 directly to the Moon?

And before anyone asks, can also land on the moon using convenient lithobraking maneuvers.

Wolfram66 · « **Reply #470 on:** 02/04/2018 06:37 pm »

SpaceX should have some seismic recording devices for the FH Launch to get data to apply to BC construction. Vibrio-acoustic influence in saturated soils is very tricky. No one has done a from scratch launch site construction for a vehicle of the power of FH since LC-39A/B. By that time, construction on Cape Canaveral was well understood. BC is virgin territory and coastal soils are not logos [Snark implied]. More data is always helpful in initial geotechnical design.

Jim · « **Reply #471 on:** 02/04/2018 06:40 pm »

Not really, Delta IV, New Glenn

woods170 · « **Reply #472 on:** 02/04/2018 06:59 pm »

Quote from: Jim on 02/04/2018 02:58 pm

Quote from: Robotbeat on 02/04/2018 02:51 pm
Simply stretching the upper stage of FH would basically null out any performance difference. And adding a kick stage on top of *that* would allow FH to launch Europa Clipper direct to Jupiter like SLS.

There is no kick stage for Europa Clipper on FH. "Kick" stages are solid motors which have high thrust. Solid motors and Falcon are none starters.

There is no stretching of the upperstage. there is no more F9 development.

Europa Clipper on FH would use gravity assists.

Why are we even discussing this? Europa Clipper is mandated by law to fly on SLS. End of story.

woods170 · « **Reply #473 on:** 02/04/2018 07:04 pm »

Quote from: Jim on 02/04/2018 02:53 pm

Quote from: Robotbeat on 02/04/2018 02:44 pm
Doug was being disingenuous. You would not launch a large payload to such high energy trajectories on any EELV or Falcon without a kick stage. Atlas V with kick stage is cheaper & higher performance than D4H without one (which is partly why New Horizons did just that), and FH plus kick stage beats them both.

Not true. Only high speed missions like PNH and PSP need kick stages. Mars, Jupiter and Saturn missions don't and that is where FH falls short.

People here seem to forgetting that the main business for FH will be GTO/GEO missions.
All this nonsense of putting a high-energy upper stage on FH, for one-off NASA missions to the outer solar system, is exactly that: nonsense.

Space Ghost 1962 · « **Reply #474 on:** 02/04/2018 07:40 pm »

Quote from: woods170 on 02/04/2018 07:04 pm

Quote from: Jim on 02/04/2018 02:53 pm
Quote from: Robotbeat on 02/04/2018 02:44 pm
Doug was being disingenuous. You would not launch a large payload to such high energy trajectories on any EELV or Falcon without a kick stage. Atlas V with kick stage is cheaper & higher performance than D4H without one (which is partly why New Horizons did just that), and FH plus kick stage beats them both.

Not true. Only high speed missions like PNH and PSP need kick stages. Mars, Jupiter and Saturn missions don't and that is where FH falls short.

People here seem to forgetting that the main business for FH will be GTO/GEO missions.
All this nonsense of putting a high-energy upper stage on FH, for one-off NASA missions to the outer solar system, is exactly that: nonsense.

Exactly.

And that's an advantage, not a disadvantage. Means that FH, unlike DIVH (and more like Atlas VH if it had happened instead of DIVH), stands a good chance of high cadence use. We'll see three this cumulative year, it took five years to do that with DIVH).

A low cost kerolox platform has totally different economics, especially when a frequently flown and reused side boosters takes much of the additional cost away from the difference with a regular F9 launch. (DIVH was all about everything being specially built, Atlas VH would have been everything the same, even better in commonality than even F9/FH).

So what's it good for? Heavy GTO, NSS. Those need heavy payloads.

Any growth? Possibly lunar tourist via Dragon 2.

Anything more? Wait for 5-8 years and see what payloads get built to take into account.

But if you're looking for significant delta-v for interplanetary, you might get FH to work for you, ... but that's not what it was designed for. Atlas V and Vulcan were designed for it, and hold advantages. Look to BFR/BFS if you want more.

Stuck with FH and you still want more? Find a way to get a fully fueled F9US on parking/transfer orbit rather than a new stage, still a difficult thing, but at least you're reinvesting in the same architecture/US.

AncientU · « **Reply #475 on:** 02/04/2018 08:37 pm »

FH could deliver propellant to fill the Vulcan upper stages for BEO operations in the early 2020s. ULA was one time discussing $3M/tonne... 50tonnes ($150M) would make a great weekly payload.

And also recall the the EUS has not yet had its CDR -- it is still a PowerPoint. If you wanted a methlox upper stage refueling system like ACES, the hardware could be flying in a couple years, compared to the 2023-2025 for EUS. The combination could make a quite nice start on infrastructure needed for a COTS Lunar effort.

But maybe FH will just be used to launch commercial payloads that would require an expended F9. Nothing wrong with that.

envy887 · « **Reply #476 on:** 02/04/2018 08:57 pm »

Quote from: Jim on 02/04/2018 02:53 pm

Quote from: Robotbeat on 02/04/2018 02:44 pm
Doug was being disingenuous. You would not launch a large payload to such high energy trajectories on any EELV or Falcon without a kick stage. Atlas V with kick stage is cheaper & higher performance than D4H without one (which is partly why New Horizons did just that), and FH plus kick stage beats them both.

Not true. Only high speed missions like PNH and PSP need kick stages. Mars, Jupiter and Saturn missions don't and that is where FH falls short.

How does it fall short? FH can send more mass direct to Jupiter than DIVH can, and for far less money.

Nether can send anything direct to Saturn, all Saturn missions would have at least 1 gravity assist so the injection c3 is no higher than Jupiter transfer.

Lar · « **Reply #477 on:** 02/04/2018 10:20 pm »

Quote from: AncientU on 02/04/2018 08:37 pm

FH could deliver propellant to fill the Vulcan upper stages for BEO operations in the early 2020s. ULA was one time discussing $3M/tonne... 50tonnes ($150M) would make a great weekly payload.

SpaceX collecting money from ULA for delivered propellant is just too delicious....

su27k · « **Reply #478 on:** 02/05/2018 03:47 pm »

Quote from: Jim on 02/04/2018 02:58 pm

Quote from: Robotbeat on 02/04/2018 02:51 pm
Simply stretching the upper stage of FH would basically null out any performance difference. And adding a kick stage on top of *that* would allow FH to launch Europa Clipper direct to Jupiter like SLS.

There is no kick stage for Europa Clipper on FH. "Kick" stages are solid motors which have high thrust. Solid motors and Falcon are none starters.

What does this mean? SpaceX doesn't like solids, but I think they're open to use solid kick stages from someone else, didn't they submit a bid for Solar Probe Plus using 3rd party solid kick stage?

sghill · « **Reply #479 on:** 02/05/2018 04:11 pm »

Quote from: groundbound on 02/04/2018 06:05 pm

Quote from: Svetoslav on 02/04/2018 03:17 pm
As for lunar trajectories, can FH send a Dragon 2 directly to the Moon?

And before anyone asks, can also land on the moon using convenient lithobraking maneuvers.

"Lithobraking"

We need to add that new term to the NSF online space terminology dictionary.

Where is that thing these days anyhow?