Author Topic: FH to the moon? (Read 42701 times)

Xspace_engineerX · « **on:** 12/22/2013 09:09 pm »

Hey guys,

Question about possibility here:

Assuming that FH gets the performance that spaceX has been claiming, and that spaceX develops a crewed dragon with propulsive landing capabilities to 2016, could they theoretically do a moon mission with FH/dragon?

I have no idea if we have the information to do the math here, but I assume that some of you guys are a lot better informed

M129K · « **Reply #1 on:** 12/22/2013 09:15 pm »

Quote from: Xspace_engineerX on 12/22/2013 09:09 pm

Hey guys,

Question about possibility here:

Assuming that FH gets the performance that spaceX has been claiming, and that spaceX develops a crewed dragon with propulsive landing capabilities to 2016, could they theoretically do a moon mission with FH/dragon?

I have no idea if we have the information to do the math here, but I assume that some of you guys are a lot better informed

They could, with a dual launch scenario. Dragon is short on Delta V though, so a lunar lander possibly based on the Kestrel or Superdraco engine would be necessery. I'll draw up something that makes use of Falcon Heavy later.

Kaputnik · « **Reply #2 on:** 12/22/2013 09:21 pm »

We don't know the isp of the super-draco, the prop loading of the Dragon, and therefore the delta-v of the spacecraft as a whole. but I think it's a very safe bet to say that it is far, far short of what's needed to de-orbit and land on the moon, let alone take off again.

Oh and there are probably a lot of issues around communications and thermal environment flying a Dragon beyond the ISS.

Orbiter · « **Reply #3 on:** 12/22/2013 09:31 pm »

FH could probably easily do a circumlunar mission with a Dragon however. But for a full-up landing and return? You'd need a Falcon X at least.

meekGee · « **Reply #4 on:** 12/22/2013 10:29 pm »

Dragon is short on dV, but definitely not on thrust.

So at a basic level, with some sort of extended trunk, it might be possible.

All hypothetical though, since I don't think SpaceX cares to invest the time and energy towards that, even if they got paid for it. "Not on the way to Mars".

Jim · « **Reply #5 on:** 12/22/2013 11:00 pm »

It would be a one way trip. Dragon doesn't have the DV for lunar launch and TEI. Nor does the FH have the capability to lift the necessary propellant to enable it to.

Rhyshaelkan · « **Reply #6 on:** 12/22/2013 11:25 pm »

thanks for the link manboy

llanitedave · « **Reply #7 on:** 12/22/2013 11:31 pm »

I'm sure that three Falcon Heavies could do an Apollo-scale mission. Just because the launch vehicles would be relatively inexpensive, though, doesn't mean the mission hardware would be.

TrevorMonty · « **Reply #8 on:** 12/22/2013 11:54 pm »

I was wondering if a reusable 2nd stage (LOX-LH2 fueled version) for FH could deliver a Dragon to L1 or LLO, partially refuel using lunar supplied fuel and return to earth.
Trip scenario would be
1) Earth to L1or LLO, passenger transfer to lunar lander.
2) 2nd stage with Dragon still attached would partially refuel using lunar supplied fuel.
3) Return passengers would transfer from lander to Dragon
4) Dragon would separate from 2nd stage just before earth re entry. 2nd stage may have to do a burn to slow its re entry speed.

PS: I mentioned this in another thread thought this would be better place for it.

savuporo · « **Reply #9 on:** 12/23/2013 12:04 am »

Quote from: manboy on 12/22/2013 11:07 pm

http://images.spaceref.com/news/2011/21.jul2011.vxs.pdf

Isnt Rohrabacher still waiting for an answer on this one, or did he give up ?

ClaytonBirchenough · « **Reply #10 on:** 12/23/2013 12:53 am »

First, I doubt FH will have the performance claimed by SpaceX for sometime.

"to the moon"...

Circumlunar? possibly

LLO? possibly

Lunar landing? no

cleonard · « **Reply #11 on:** 12/23/2013 01:29 am »

Lunar landing, sure. Soft lunar landing, no.

How about a so called free return trajectory around the moon and recover the Dragon. Is there enough deltaV in a stock dragon fro that?

sdsds · « **Reply #12 on:** 12/23/2013 01:35 am »

I guess the interesting mission mode would involve two launches and a lunar orbit rendezvous. The first launch would put an uncrewed Dragon into lunar orbit, to be used for the trans-Earth return and landing. The crew would then launch directly to the lunar surface in a second Dragon, then lift off from the Moon and rendezvous with the Earth-return vehicle in lunar orbit.

No need for depots. No need for propellant transfer.

jketch · « **Reply #13 on:** 12/23/2013 01:51 am »

The problem is that a dragon doesn't have nearly enough delta-V to land on the moon and then get back to LLO. Delta-v from LLO to the surface is 1.87km/s, so even if you had a fully fueled vehicle in LLO, you'd need 3.75km/s of delta-v to do it, which Dragon isn't anywhere near having. A direct descent from EML-1 to the moon and back is even more costly, you'd need 4.3km/s to do the round trip. All of this is per wiki, so take it with a grain of salt, but I doubt their delta-v numbers are too far off.

http://en.wikipedia.org/wiki/Delta-v_budget

Xspace_engineerX · « **Reply #14 on:** 12/23/2013 01:55 am »

Anyone have a number as to what delta-v crew dragon is going to be capable of

Avron · « **Reply #15 on:** 12/23/2013 02:09 am »

I for one would be thrilled with a FH free return and even more happy with a circumlunar trip in the next three years. I think this is a distinct possibility, based on existing technology and some that may be hiding at Vandenberg (FH)

Lars_J · « **Reply #16 on:** 12/23/2013 02:51 am »

Quote from: Xspace_engineerX on 12/23/2013 01:55 am

Anyone have a number as to what delta-v crew dragon is going to be capable of

It will be difficult to get a full handle on, since the amount of delta-v in low thrust mode (Draco) is going to be significantly higher than in high thrust mode (inefficient non-vacuum-optimized super Draco). To land on the moon, you will need much more thrust than just the Draco thrusters can provide.

ArbitraryConstant · « **Reply #17 on:** 12/23/2013 02:54 am »

Quote from: Jim on 12/22/2013 11:00 pm

It would be a one way trip. Dragon doesn't have the DV for lunar launch and TEI. Nor does the FH have the capability to lift the necessary propellant to enable it to.

Seems like it would require 2+ launches, an EDS, replace Dragon's trunk with an actual service module, and build a new lander from scratch.

heinkel174 · « **Reply #18 on:** 12/23/2013 02:55 am »

Quote from: Xspace_engineerX on 12/23/2013 01:55 am

Anyone have a number as to what delta-v crew dragon is going to be capable of

Likely a few hundred m/s. IIRC Soyuz has around 400m/s.

By contrast the Apollo CSM can do 2800m/s but more than 60% of its mass is propellant. So you need a massively boosted Dragon.

Lobo · « **Reply #19 on:** 12/23/2013 03:12 am »

Quote from: ArbitraryConstant on 12/23/2013 02:54 am

Quote from: Jim on 12/22/2013 11:00 pm
It would be a one way trip. Dragon doesn't have the DV for lunar launch and TEI. Nor does the FH have the capability to lift the necessary propellant to enable it to.
Seems like it would require 2+ launches, an EDS, replace Dragon's trunk with an actual service module, and build a new lander from scratch.

Really depends how what scale of mission you are looking for.

As has been pointed out, Dragon doesn't have the dV to get down and back up.
However, you could do a few things.
1) Lunar Direct. Land Dragon on it's superdracos, with a disposable propellant stage under it. As the superdracos are angled, if the prop stage isn't wider than Dragon, there shouldn't be a plume impingement problem. you -might- get such a mission in a single launch. it would be pretty limited though. Probably about as capable as the Russian LK missions would have been. And the dragon capsule isn't the best for staging EVA's out of obviously.
The angled Superdracos also mean you loose efficiency. But, they are powerful enough, you might get away with it if you can carry enough extra prop in the prop stage.

2) Apollo-light. Two FH launches. one launches Dragon to LLO (would need additional prop in a service module.). Another launches an unmanned lander to LOR with Dragon. The lander could use superdracos for it too. This would probably be less capable than Apollo, unless an additional hydrolox stage was used to boost FH's TLI capacity.

3) Apollo+. Launch Dragon with a service module on one launch to LEO on the first FH. Launch a lander on another FH to LEO. And then launch a dedicated hydrolox CPS to LEO for EOR of the 3 elements before doing the TLI burn. I would think you could get something a little more capable than Apollo with that. The limitation would be the size of the hydrolox EDS you could get up. The first two FH launch might put more mass into LEO than the 3rd FH's EDS could get through TLI. Although, you might be able to do a two stage burn. The FH upper stage doing the first part of EDS burn if it gets to LEO with residuals. Then it's discarded and the hydrolox CPS does the rest. A Dragon with a large SM would brake itself and the lander into LLO just like the Apollo CSM did.
You'd need three pads at the Cape that could launch the 3 elements in rapid succession though. You might be able to do it with just two though. Launch a hypergolic lander into LEO to loiter. Then prep the crew on the dragon CSM and the hydrolox CPS at LC-40 and LC-39A. Launch the CPS first to mate with the bottom of the lander, and once that operation was successful, quickly launch the crew on dragon to dock with the lander like Apollo did with the LEM. Burn for TLI before there's too much boiloff.