Alpha 360

Dres Spacecraft - Is it enough?

Recommended Posts

Alright. I have a Dres spacecraft which I want to go to Dres. Since I am using a mod that rearranges the planets, I can't us a delta-v map. But with TWP, I have calculated the transfer windows and stuff. 

I have USI life-support, so that means life-support is in the picture. 

Here are some of the numbers to run. 

With my current recycling abilities, I can reduce supplies per kerbal to 2.3 daily. 

There are 4 kerbals on-board the spacecraft. 

That means 12.8 supplies daily. 

The mission is set to be  about 700 days long, and therefore I want 50 extra day's worth of supplies for margin's sake. That is a total 750 days of supplies. 

750 days worth of supplies at 12.8 supplies daily is 9,600 supplies. 

I'll bump that up to 10,000 supplies so now I have an ample margin of error. 

For the delta-v side of things, I need 3,000 m/s to arrive from Kerbin orbit to Dres orbit. It then takes another 3,000 m/s back to Kerbin. But the ejection burn from Dres to Kerbin is half of the delta-v meaning that if I throw away the spacecraft, I could use a smaller one. Or just do a bunch or areo-braking, which I am fine with. 

I will be coming out with new numbers as soon as I can. The reason I am doing this is so people can see my work and critic it so I could have a better spacecraft to visit Dres with, and to prevent my kerbs from dying. 

Also here is a pic of it so far. The transfer stage is missing presently. I do have a poodle for orbital maneuvers, but that will go soon. 

pmv2BO22p

pmYw1k8Bp

pmW8bWpAp

Happy Explosions!

Share this post


Link to post
Share on other sites

Save then try. Fail? Accept failure or reload. Success? Smile.

Since we can't see exactly what you're doing it gets very difficult to give you a yes or no. The only way to be sure is just go for it and find out.

And if, for RP reasons, you don't want to reload; test it in a separate sandbox game. And call it a 'simulation' by the boys in mission control.

Edited by Tex_NL

Share this post


Link to post
Share on other sites

I'm playing on a no quicksave career mode. Also, with the mod I'm playing with, I have to wait for a new sandbox game to be fully visualized. I know I could suck it up and wait, but I think it would be interesting to do the mission with math instead of luck. :wink:

Share this post


Link to post
Share on other sites
8 minutes ago, Alpha 360 said:

I'm playing on a no quicksave career mode. Also, with the mod I'm playing with, I have to wait for a new sandbox game to be fully visualized. I know I could suck it up and wait, but I think it would be interesting to do the mission with math instead of luck. :wink:

You have enough Delta-vee.  Go for it!  Do you have a detachable lander?

(And if you get stranded, thats a good plot point.(Or you could get someone else to rescue you.))

Share this post


Link to post
Share on other sites

The point is that that delta-v number is estimated. As well as the fact I need to finish designing the transfer stage. Funnily enough, my story about Mr. Kerman is a little bit ahead for its time.... That was not intended.

Share this post


Link to post
Share on other sites

I don't know how helpful this is, but I realized that for many trips, most of the time is coasting. So if life support supplies (and their containers) are heavy, you want to stage them. Ideally you are never burning with any empty containers.

So I have three LS container stages. The first one gets dumped before I burn for capture. The second gets dumped before I burn to go home, the last gets dumped before capture at home. I typically also have a couple of weeks on LS in on the Kerbin capture stage, in case I need to do a two-pass capture. This is using Snacks!, which mostly just adds a mass penalty for LS.

 

Share this post


Link to post
Share on other sites
26 minutes ago, Alpha 360 said:

The point is that that delta-v number is estimated. As well as the fact I need to finish designing the transfer stage. Funnily enough, my story about Mr. Kerman is a little bit ahead for its time.... That was not intended.

You don't have to estimate.  Dv=9.8 * isp * ln(drymass/wetmass)

Edited by DAL59

Share this post


Link to post
Share on other sites

@Alpha 360 - Er, exactly what do you need help with?   It seems like you have everything covered -- TransferWindowPlanner will tell you both the flight time and required delta-v, very precisely.  The only thing you'd need to add in there is how long you plan to be at Dres - you'll need to cover that too.  That 750 is covering the round trip, right?

If you want a smaller ship, one thing you could do is send the life support for the RETURN trip on ahead with a probe-driven craft, and then only send the kerbs with a one-way LS load, dock at Dres, transfer the return LS, and then head back.

Here's a checklist of things that could go wrong, depending on various factors:

  • Is Dres still an outer planet in this scenario?  will those solar panels provide enough power for LS and to cover the recharge after being in Dres' shadow in that case?
  • Is it an inner planet?  Will heat be an issue?
  • Will you need fuel for landing modules?
  • Is radiation modeled in USI?  Do you have enough shielding in that case?
  • Will the Kerbals get cabin fever? 
  • Are there supplies aside from LS and fuel that need to be addressed (monoprop/reactor fuel/etc?)
  • Does IPS4 suck totally and completely?

(I really don't know what USI entails and have heard of all sorts of complex mods that handle things like radiation and cabin fever and such)

By the way, as another alternative to sending a probe with life support, send an absolutely minimal probe without life support, and see how long it takes/how much delta-v it burns.  That'll safeguard your kerbs against unpleasant surprises, although TWP gives you EVERYTHING you need with a very high degree of accuracy.

Share this post


Link to post
Share on other sites

I have USI life-support, so that means life-support is in the picture. 

Ok.  So at a 700 day (or more) travel time, you probably want to look at Agroponics rather than recycling.  10k supplies plus recycling facilities will weigh a significant amount - I assume around 13ish tons.

What agroponics can do for you instead is you take a small amount of supplies, a big chunk of fertiliser, and an agroponics module.  The rule you need is:

1 Fertiliser + 10 Mulch = 11 supplies.

So Kerbals eat supplies, turning them into Mulch.  Agroponics module takes a pinch of fertiliser, adds it to the mulch - and you have supplies again.  (Don't forget a mulch container, doesn't have to be a big one).

What this effectively means is that fertiliser = 11*supplies.  Typically for a mission of this sort I would start with supplying them with a couple of thousand supplies, a full 5k tub of fertiliser, and that is sufficient to keep them going for at least 15 years (I've not had a longer mission but I suspect it would be fine).  My interplanetary crew transports are more limited by habitation time than supplies at this point.

Here's my example around Dres.  Approx 30 tons for the payload (much more for the Shunt!)

FnAcn0i.png

It should be noted that you will need some machinery (500 will last for at least 6 years), and you will likely need a Scientist aboard - so if either is a no-go then stick with recycling.  I think you should be able to manage an agroponics setup that will actually give you less mass than if you plan to go down the recycling route  - and give you much longer supplies time.

 

Edited by bigcalm
clarification.

Share this post


Link to post
Share on other sites

Surprised no one pointed out that any mission to Dres is to much ship for Dres.  No one goes to Dres.

I have done Duna missions with TAC and the life support is so light that packing on 3-4 years of supplies is easier then doing high energy transfers.  However the further out you go the more high energy transfers make sense.

Personally when it comes to life support I like 2x supplies as it is generally needed if you want to mount a rescue mission in time if needed.  You can also always to a 2 phase mission.  Phase 1 Holman transfer station and supplies.  Phase 2 high energy transfer crew.

Share this post


Link to post
Share on other sites

Are you considering asteroid/surface ISRU?

Can you mine for water and crack to oxygen to save yourself a third of the tonnage?

Share this post


Link to post
Share on other sites
1 hour ago, suicidejunkie said:

Can you mine for water and crack to oxygen to save yourself a third of the tonnage?

Actually, I'm doing this in career mode, as I might have mentioned before. In this career mode game, I haven't unlocked any fancy stuff yet, not even Twin=Boar Engines or Recycling, or Mining. Zilch. 

This mission is very low tech, so that is why it is so large. I need quantity, not quality. 

On ‎2‎/‎14‎/‎2018 at 2:47 PM, Nicias said:

don't know how helpful this is, but I realized that for many trips, most of the time is coasting. So if life support supplies (and their containers) are heavy, you want to stage them. Ideally you are never burning with any empty containers.

That's for that! That is an amazing idea that I should try.....later. The main body of the spacecraft has already been determined so I can't make any major changes. What I can change is the transfer stage which hasn't been launched, even now. 

15 hours ago, Renegrade said:
  • Is it an inner planet?  Will heat be an issue?
  • Will you need fuel for landing modules?

It is an inner planet, but I have included  couple of radiators just in case. Yes, I will need fuel for landing on Dres. I think I will simply just send it up full of fuel, isolate it, then when we arrive at Dres, detach and land. 

Thanks for all of this feedback! It is really nice of all of y'all!

Happy Explosions!

Share this post


Link to post
Share on other sites
7 hours ago, Alpha 360 said:

That's for that! That is an amazing idea that I should try.....later. The main body of the spacecraft has already been determined so I can't make any major changes. What I can change is the transfer stage which hasn't been launched, even now. 

There's also my favorite option:  DeepFreeze Continued. Why pack food for years and years when you can just stuff the crew in the freezer except for the brief period when you let them out to plant a flag at the destination?  Failing that, growing your own food is by far better for long trips than recycling, as @bigcalm says.

NOTE:  Any and all rumors that freezing Kerbals always results in severe psychological issues and/or zombie outbreaks are just that:  rumors :)   Certain regrettable incidents where such things are rumored to have happened were entirely caused by the intervention of the D100 of Destiny outside the game and had nothing at all to do with the functionality of this great mod.

Share this post


Link to post
Share on other sites

Thanks for reminding me of that mod, @Geschosskopf. That is a very usual mod that I should download.......Actually I'll do that soon. Thanks!

Happy Explosions!

Share this post


Link to post
Share on other sites

If you have KIS/KAS, you can stage radial LS tanks off with minimal mass penalties by having an engineer EVA to unbolt them.

Share this post


Link to post
Share on other sites
This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.