Musk Mission to Duna

[Kurtstudent]

Hi all,

 Hi,

I've been away from the space program for a couple of months.   I had a complete working almost identical shuttle program.   Unfortunately due to an issue I completely uninstalled  including my saved games. 

 I have been unable to  recreate my shuttle in the latest patch .   So it's got me thinking and  Since I've also lost my  Mars ascent  vehicle, again  an almost  identical re-creation of  the ship in the Martian.  

 I decided to copy Musks ships.  

 I can't get them to work,   As there is an incomplete parts list on the standard game.

 

 Has anybody yet had the opportunity to recreate this and what parts did they use, as it appears we need items that are non-stock 

 

 Thanks in advance 

[B-STRK]

Haven't had the opportunity to BFR, but seen some in action, and these are my observations of them. So the tl;dr is yes it can be done stock, but you'll have to decide first exaxtly what size in KSP you'd consider a BFR: Mk3, or larger?

About the only non-stock item I could think of, based on all I've seen here, in the KSP reddit, and Youtube are the landing legs, because there's none that are big enough--although you could use structural parts or tanks to extend them past the ship's butt end and extend past the engines (for example, use the cargo bays as engine fairings and mount the legs onto that), and if you're scaling the ship up to the intended BFR scale the stock legs alone won't be able to take the weight--you'd be spamming legs otherwise. In that case though, nothing wrong with landing very gently on the engines if you can manage it.

Anyway there have been, at the very least functional recreations, and eben those that capture the BFR profile as well, most I've seen on YT and reddit. For those pursuing the Mk3 profile as the BFR size, the cargo ramp makes a nice BFR beak/cargo door. Larger in stock, I've seen clustering of fuselages and tanks to achieve BFR-type profiles. To get larger cargo bays than Mk3, one could try combinations of stock fairings and hinges to create a larger-than-stock cargo bay with a swing-out nose door. (Don't know how to do hinges, sorry, but I think there's a tutorial somewhere here).

Simplest Mk3-type profile for the BFR would be the ramp and cargo bay (or the ramp, Mk3 passenger and clipping a Mk2 cockpit for the pax model), fuel tankage (all Mk3 or Mk3 + adapter to 3.75 and tanks), and whatever engines gets you there (usually the larger Size 2s, the Rhino (probably overkill though) and the Vectors, add wing parts on the ventral aft surface. One can probably play with that, adding more tanks or clustering, to get the desired performance (dV= LKO-->Duna surface) out of the ship.

[Rune]

I've got a couple of takes on it, but I've yet to test them thoroughly:

The thing is, I don't really like that cocodrile bay door, it doesn't fit the outline of the crewed version, just the one shot of the thing lunching satellites. So I made a crewed version, and it kinda works better because of the tank/weight distribution being much more sensible than in the real thing. That made the whole aerodynamic balancing act to reenter it belly-first and then flipping it close to the ground, well, much easier with much less wasted weight in wings. In the end, it has the same payload, but it has a crew capsule with abort capability on top, and a lower total weight:

They are a bit tricky to launch in pure stock, but it is possible to recover the booster without resorting to quicksave-quickload in the same flight, I've done it several times now. It just takes a 'slightly' inefficient 4.5km/s launch (meaning I'm wasting around 1km/s), and a lot of switching around at the appropiate time, but hey, fully reusable TSTO ~20mT launcher. Not that I don't have lighter chemical SSTOs that can do the same thing...

It is obviously scaled quite a bit down, but you know, KSP scale. I couldn't fit 31 engines in the first stage, six in the second, and make the staging make sense in kerbal scale, so I took out the outer ring of 12 on the booster, and scaled it to something that fit under the biggest stock tanks, turned out to fit the launch requirements (TSTO) quite well using the humble LV-T45 and 30 as Raptor analogs. The spaceship has the proper number of engines, at least, and the whole thing looks like the BFR if you squint, right?

 

Rune. Coming Soon™.

Edited October 11, 2017 by Rune

[NSEP]

I tried it once, but landing it is just hard, i dont know how its exactly done but when i try, its way too nose heavy and hard to turn upright, almost like a Space Shuttle loaded with bricks on the front.

[Kurtstudent]

Rune. That's awesome.  What about using mechjeb and switching to aid landing and also orbit fine tuning?

[Rune]

On 15/10/2017 at 10:12 PM, Kurtstudent said:

Rune. That's awesome.  What about using mechjeb and switching to aid landing and also orbit fine tuning?

Well, I guess that would make things easier and more repeatable. But, you totally don't need it. The only trick really is to leave the booster with the same-ish apoapsis every time, so you have the same time to put the spaceship on a long (>2min) coast to apoapsis that gives you time to switch back to the booster to land it while that is going on. Basically you just have to remember at which point to stage (I use '500m/s left on that stage' thanks to KER, I'll have to work out the fuel level for that in order to give the stock flight manual), then do a bunch of steps mechanically each time, with a nail-biting suicide burn required to land the booster. I think I can condense all that into a 'simple' flight manual of no more than ten discrete steps, using stock instrumentation. Note that I've never been able to do it without KER's suicide burn indicator, that is true, but I guess if you are Scott Manley and/or I work out the exact height to start it...

 

Rune. Chutes would also probably help, but they wouldn't be accurate.