"ROh : The Martians" : live designing of a 6 manned mission to mars [day 6, 35 hours spent]

[Pro7ech]

[Day 6 : 08.11.2015]

Hours spent on the project : 35

CURRENTLY : designing a series of launchers that will allow me to send stuff in LEO with various capability (based on the SLS).

Some updates about the launchers :

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Hi everyone, this is my first ever serious post in here. My native language is french.

My goal is to bring 6 Kerbals from Earth surface to Mars surface, make them stay here 90 days, do some experiments, and bring them back safely. When the whole story will be done, I'll make a short video of the trip.

I have been playing with Realism Overhaul for more than one year, and I wanted to make something meaningful now that I'm used to its difficulty.

I will keep track of the project here, posting everyday (or nearly) updates and pictures of it.

For the addons used, see the spoiler at the end of the post.

1) The first goal is to design everything on paper : how I will do it and what I need to do.

Firsts launchs [unmaned] :

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1x Establish a communication network around LEO, LMO and bewteen Earth and Mars

First thing to do is put a GEO (more or less equatorial) communication network (~40'000km orbit) made of 3 satellites allowing 100% uptime comms in LEO : DeltaV budget : ~14000m/s

I designed a rocket able to put ~500kg in a GEO orbit. Total deltaV : 14460m/s (+1086 in the satellite). I will launch 3 of them this afternoon. With my first sat I ended up with 300m/s of DV. So for the second, I removed those 300m/s, except that this time I also ended up with some DV left, around 700. So for the last satellite, I made a much smaller rocket (50% less mass for only a little less DV ~13600m/s). I worked very well, I even had 450m/s of DV left.

Sucess! I made a video, hand piloting from a-z without using the map (only looking at numbers from the mechjeb). With my last rocket (the most optimised one), I ended up using a DeltaV that was really near the theorical needed. I was surprised of my launcher performance (nice T/W ratio for all the stages) and my hand piloting.

About the album, the rocket with the 4 SRB is the first design. The rocket with the 2 SRB is the second design, and it is much less heavy (from 658 tonnes to ~330 tonnes = ~50% less) for the same payload delivery with a much better balance in T/W ratio among all the stages.

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1x Vessel capable of bringing 6 Kerbals from Mars surface to LMO + 2000kg of stuff

Currently designing this vessel. It needs to land on Mars without local control, and be able to bring back 6 kerbals + various stuff into LMO and dock with the interstellar ship.

Mars atmosphere being very thin, the vast majority of the deceleration must be done by burning properllant if you are bringing a heavy load. But it also has the advantage of not heating a lot the vessel, so over heating will not be a problem (except maybe for parachutes).

It will have 3 stages. One main stage for the descent, a second stage for the ascent and partial orbit insertion and the last stage for the final kick and orbital manœuvre.

The first two stages (the ones designed to leave mars) are in there final design and they work pretty well. The main problem I encounter is the lack of reignitable engines for the descent stage, the first stage. I can not find powerful enough engines using hypergolic propellants that are reignitables.

My plan is to decelerate under 1000m/s (from a ~4000m/s initial speed) using hypergolic properlant (I can only use hypergolic props for all the stages, they need to be stored for a long time), cut engines and use chuts to control the speed of the decent and keep it at a reasonable speed, and reignite for the last few hundred meters and land it safely.

Update : I found how to change the number of ignitions. See this thread if you are interested. This allows me to use engines that I could previously not use (I need 2 ignitions for the descent). Back to the design lab.

I am asking myself if it would be realistic to have a "light" vessel, and fuel it on Mars (bringing fuel from an other transport). I already know I will have to launch it empty and fuel it in LEO, but what about saving fuel by only leaving what is needed to land on mars and send the rest with parachutes, Kerbals using pipes to fuel it before the launch. Hmm... I might consider this if the DeltaV of the first two stage is not high enough.

Finaly, with the new design, I can get it fully fueled on mars. But I will still send it empty in LOE, and fuel it in orbit.

With the new engines, I'm saving 60 tonnes, going from 300 to 240 (fully fueled).

Update : new design is 201 tonnes fully fueled! And 70.5 tonnes when landing on Mars.

Update : final design validated. Now I need to tweak some fuel quantity and calculate the smart config for the automated landing. Smart part will work like this : at x altitude activate timer + engine + arm parachutes. When timer expire cut off engines (I want to cut off when I get to ~10'000m above the surface). Then I let chutes do the job and use a second smart part to activate engines at x altitude + timer to make it land at only a few m/s from the ground.

I made a spread sheet to calculate :

Chute speed : using parachute number, parachute diameter, atmosphere density, gravity, vessel mass and drag coefficient : number found : 65.7 m/s

Burn time to compensate for the chute speed : using engine thrust, vessel mass, gravity, and chute speed : number found : 3.82 sec

Altitude to start burning : using the vessel initial chute speed, the burn time calculated from the previous formulas and the deceleration speed : number found : 125.6m (I will add 10m for safety).

I managed, after hours of reloading (and awhhh... I had to factor the height of my vessel haha xD ~15m from the ground to the control unit), retuning, to get a my settings perfect landing (less than 2 m/s) on mars with the return vessel. I tried it a few times, it works every times \o/ First stage allows me to land with 150 m/s of DV left. Second stage allows me in one burn to get at 3200 m/s and an apoapsis of 346km. Third stage allows me to circularize and meet the interstellar return vessel.

Most of the hard job is done about this vessel. Now I need to find a way to get it to Mars. Will do an other day Its only 31 tonnes when empty, so should not be super hard.

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1x Habitat capable of sustaining 6 kerbals for 90 days

1x Other stuff (rovers, comms, solar pannels, etc...)

Second launchs [manned]

1x Vessel able to bring 6 kerbals from LMO to Mars surface

1x Interstellar vessel able to do two times the trip from LEO to LMO and sustain 6 kerbals for 4 years

Other launchs [manned]

2x Vessel able to bring 3 Kerbals from Earth surface to LOE

2x Vessel able to bring 3 Kerbals from LOW to Earth surface.

- AJE

- Active Texture Management

- AIES

- B9 Procedural Wings

- Better Atmosphere

- Better Buoyancy

- BobCats Soviet Engines

- CrossFeed Enabler

- Community Ressource Pack

- Deadly Reentry

- Distant Object Enhancement

- EVE

- FAR

- Filter Extension

- Habitat Pack

- Hangar Extended

- Kerbal Attachement System

- Kerbal Joint Renforcement

- Addon version checker

- KW Rocketry

- MechJeb

- ModuleRCSFX

- Near Future Propulsion

- Near Future Electrical

- Near Future Solar

- HyperEdit

- Procedural Fairings for Everything

- Procedural Parts

- RCS Build Aid

- Real Chute

- Real Fuels

- Real Heat

- Realism Overhaul

- Real Plume

- Real Solar System

- Remote Tech

- Renaissance Compilation

- RLA Stockalike

- Saturable RW

- Smart Parts

- Smoke Screen

- Stock Revamp

- SXT

- TAC life support

- Texture Replacer

- Tweak Scale

Edited November 8, 2015 by Pro7ech

[TheAurora]

Cool project! I hope to hear how this goes. I have been getting into RSS myself lately. How is your RAM situation? That's a lot of mods. Mine would crash with that many. Are you running 64 bit Linux?

[Pro7ech]

Cool project! I hope to hear how this goes. I have been getting into RSS myself lately. How is your RAM situation? That's a lot of mods. Mine would crash with that many. Are you running 64 bit Linux?

Atm I run 32bit windows 10, with a base of 2.9gb, but this is without cleaning a lot of parts I do not need (all fuel tanks, a lot of command modules, some egines, all of the tails, etc...), leaving me with only what I need. I will try to make it as much beautiful as I can. I use mostly procedural parts. Since that at the moment I am only designing my vessels, I can manage running with a high memory, if it crashes after 5-6 reload, its fine. After cleaning, I guess I can get to 2.4 gb, allowing me a safe distance.

Edited October 23, 2015 by Pro7ech