Soyuz Lunar Mission

[N_Molson]

I have no idea where is the research on the on-orbit propellants transfers... It works between the ProgressM and the ISS tanks, but only for N2O4/UDMH (which is not cryogenic). The BlockDM uses LOX/Kerosene (cryogenic).

Also that would mean more dead mass : pumps, solar panels/fuel cells (for the pumps), a complex docking system to allow propellant transfer, electronics to monitor & regulate the process, hydraulics...

 

[N_Molson]

That "lunar train" should be able to do it

A ProgressM (that can be filled with propellant, if needed) could be used to dock the DM2s together. Then the manned TMA arrives and dock.

2 ProtonMs and 2 R7s are required. More Proton launches allow to dock more BlockDMs together.

Defined as a "fairing" like in the Zond exemple in Proton_LV, the rear docking adapter of the central BlockDM2 can be jettisoned, revealing the nozzle.

Attitude control requires patience, but it's possible to control the thing.

 

[Wishbone]

And this stack is why I need to write down a more efficient attitude autopilot (of the bang-wait-bang variety). Otherwise one push of a square bracket button will suck dry one's TEI...

 

[N_Molson]

Well, the key is to use the Soyuz RCS in translation mode. Once the DM engine ignites, the attitude control is easy, thanks to the nozzle gimbal.

It would be indeed very cool to be able to reprogram the prograde/retrograde autopilots, and to assign the thrusters you need to use for pitch up, down, etc...

For exemple, I noticed that the Soyuz in translation mode fires a small thruster in the inverse direction of the two others. This is to avoid spinning, but becomes a nuisance in a "stack" configuration.

After that the possibilities would be endless : imagine docking a huge train of DMs, with a Zarya module and a Soyuz, and send the whole thing to Mars (where a lander would be waiting in orbit)

 

[Thorton]

Here is what i have


A special tug DM-L (lunar version of DM-03) is able to provide TLI and partially LOI with orbit 100*3200 km above moon.
So we need to optimize something to be able to get on the circular lunar orbit.

Also i've never heard even about possibility of docking DMs to each other, so i highly doubt that such "lunar train" is possible at all.

 

[Wishbone]

With larger stacks, in RL there are significant problems with non-rigid oscillations and structural integrity. Of course Orbiter doesn't model those now but who knows where we can land...

 

[N_Molson]

Found an interesting quote here :

The Space Review : Soyuz to the Moon ? (2004)

The Soyuz spacecraft used for Lunar Express missions would have to carry the heavier heat shields developed for the Zond program, incurring a 300-kilogram mass penalty.

Edit : what are the specifications of that BlockDM3-L ? I'd like to know them for calculation purposes.

On russianspaceflight.com :

Scenario 2: Lunar orbital mission

In order to deliver Soyuz into orbit around the Moon, four rockets would be required. Two Protons would place a pair of Block DM orbital tugs and two Soyuz rockets would launch one manned spacecraft and one Fregat orbital tugs. All four vehicles would have to dock in the Earth orbit, from which one Block DM's would be used to send the Soyuz toward the Moon and another to insert the spacecraft into lunar orbit. The Fregat stage would then send the spacecraft from lunar orbit toward Earth.

The question is : how to dock all those spacecraft together ?

What about adding a docking mechanism to the rear of the TMA Service Module ? Attitude thrusters could still be used to perform the rendez-vous manoeuvers. The docking system could be jettisoned in order to use the main engine (once the first BlockDM is spent).

 

[Thorton]

Originally it was DM-03, DM3 is commercial version of DM-2M.
M0 = 2668 kg (including docking port and supplementary systems)
Mfuel = 18700 kg
M0_SOZ = 112 kg
Mfuel_SOZ = 128 kg
Thrust = 86.3 kN
Isp = 361 s (syntin)

The question is : how to dock all those spacecraft together ?

It seems wrong for me. According to my estimation 2 Protons and 1 Soyuz rocket would be enough.
1st launch: Flagman tug (DM+Fregat) by Proton, waiting for Soyuz
2nd launch: Flagman tug (DM+Fregat) by Proton, should bring partially fuelled Fregat (>50%) to LLO, which should provide TEI and MCC.
3rd launch: Soyuz TML docks to Flagmat (1st launch) and perform TLI. MCC and LOI - by Fregat

 

[N_Molson]

Then we have, for the BlockDM3+SoyuzTMA configuration :

Dv = 361*9.81 * ln(18700+2668+7550)
Dv = 3684.18 m/s

Not bad at all, we are over 4000 m/s if we spend the TMA fuel !

The problem is that, if we stack a DM3+Fregat, we have a total mass of 29 tons. Which exceeds the ProtonM LEO payload capacity (21.3 tons, exactly the total mass of the BlockDM3).

 

[Thorton]

Then we have, for the BlockDM3+SoyuzTMA configuration :

Dv = 361*9.81 * ln(18700+2668+7550)
Dv = 3684.18 m/s

Not bad at all, we are over 4000 m/s if we spend the TMA fuel !

Hm, something wrong here, where did you find 4000 m/s? I'm asking because it's possible to put TMA+DM-L+500 kg on escape trajectory, which is require more Dv than TLI.

Also, from my Apollo flights i remember that free-return trajectory require ~3100 m/s.

The problem is that, if we stack a DM3+Fregat, we have a total mass of 29 tons. Which exceeds the ProtonM LEO payload capacity (21.3 tons, exactly the total mass of the BlockDM3).

Well, we'll need in this case additional circularization burn. I'm not 100% sure, but seems there will be still enough fuel left to perform TLI and LOI.

BTW, don forget in your calculations that at the moment of TLI Soyuz won't have full tanks, docking with Flagman takes at least 30% fuel. I believe we shouldn't count on Soyuz fuel in calculations, because this fuel will be needed for the LLO operations.

 

[N_Molson]

Yep, looks like the needed Dv for TLI is more around 3200 m/s :

For the Apollo lunar missions, the restartable J-2 engine in the third (S-IVB) stage of the Saturn V rocket performed TLI. This particular TLI burn lasted approximately 350 seconds, providing 3.05 to 3.25 km/s (10,000 to 10,600 ft/s) of delta-v, at which point the spacecraft was traveling at approximately 10.4 km/s (34150 ft/s) relative to the Earth.

Concerning the Soyuz fuel, we can assume it takes 300 kgs to dock the BlockDM3. Which is the extra mass needed for the heat shield, so we can consider the two things annihilate themselves.

Notice I don't include a Fregat in the below calculation (I forgot to type the division in the upper equation, but the result was correct), it's just the TMA docked to the DM3 :

Dv = 361*9.81 * ln(18700+2668+7250/2668+7250)
Dv = 3541.41 * ln(28618/9918)
Dv ~= 3752.78 m/s

Nevertheless, I think that launching 29 tons on the ProtonM will drain a significant quantity of the DM3 propellant. But we have to try there.

 

[Wishbone]

Folks, are you discarding any mass after emptying? Just wondering...

 

[Thorton]

Nevertheless, I think that launching 29 tons on the ProtonM will drain a significant quantity of the DM3 propellant. But we have to try there.

Yep, I've checked and after TLI Fregat doesn't have enough fuel to form circular lunar orbit.
Seems Soyuz+Tug is our bottleneck

Folks, are you discarding any mass after emptying? Just wondering...

I jettisoned SOZ (~180 kg) right after last DM ullage burn.

 

[N_Molson]

What is the SOZ ?

 

[Thorton]

2 spherical fuel tanks and 16 attitude thrusters. SOZ provide attitude control and ullage burn for DM.

 

[N_Molson]

I managed to put a Fregat in a circular LLO, using the "super-Block-DM2" with 18000 kgs of fuel. The mass of the stack at launch was around 26,5 tons.

The key to optimize the fuel consumption is to fly very low in LEO, no more than 130 kms. Anyway we're not supposed to spend more than a few orbits there.

 

[Thorton]

Yep, i did that too, but how could we put Soyuz to the circular LLO?
I believe only KVRB or KVTK could solve this problem.
Besides there is no lander and seems nobody interested in its development.

 

[Urwumpe]

Yep, i did that too, but how could we put Soyuz to the circular LLO?
I believe only KVRB or KVTK could solve this problem.
Besides there is no lander and seems nobody interested in its development.

Interested yes, but no time... I still work on the newest panel for SSU.

Otherwise, I would have no problem getting you a lander... I doubt that I am the only one who can do that. It takes just some imagination and only basic C++ skills for the start.

 

[N_Molson]

The lander seems the easy part to me (it doesn't have to be heavy). I could work on that if necessary, provided I get advice on the technical part (mass of the subsystems, etc...).

But it seems to me that we need to find a way to send the 7,2 tons TMA in lunar orbit first.

 

[Urwumpe]

But it seems to me that we need to find a way to send the 7,2 tons TMA in lunar orbit first.

The large Russian cryogen upper stage will do that. Just get the lander done...