suggestions/critics needed

[nascarlaser1]

Hi guys!

 

After lots of times where I'd start this project and never finish it, I have decided that I will go interplanetary no matter what happens. To start I am going to go to Duna. Canyou guys take a look at my ship and give suggestions/critic it so I know what to change on it? I currently have a big interplanetary ship that will take 4-5 kerbals and a 3-4 kerbal lander to Duna. The lander is docked to the side of the ship and I will be using mechjeb to set up the transfer and to do any required docking.

https://imgur.com/a/1koLm

 

Mods in use:

USI core

USI LS

Deepfreeze

Mechjeb

 

 

Thanks!

[Harry Rhodan]

You use nukes yet your tanks are full with oxidizer. I don't think you'll need rcs and monoprop on the main ship if you also have it on the lander. You will only dock with one of them anyways. Doesn't Deepfreeze make them consume no suppies? Then you don't need all those large cans full of supplies.

Those girders between the main ship and the engine pods will be extremely wobbly. Building it that wide will also make it hard to get into space. And having a large mass only on one side on a long thin lever will not only introduce a lot of wobble but also torque you would have to fight against.

[nascarlaser1]

15 minutes ago, Harry Rhodan said:

You use nukes yet your tanks are full with oxidizer. I don't think you'll need rcs and monoprop on the main ship if you also have it on the lander. You will only dock with one of them anyways. Doesn't Deepfreeze make them consume no suppies? Then you don't need all those large cans full of supplies.

Those girders between the main ship and the engine pods will be extremely wobbly. Building it that wide will also make it hard to get into space. And having a large mass only on one side on a long thin lever will not only introduce a lot of wobble but also torque you would have to fight against.

Thxs! I only had enough space to strap enough deepfreeze resources for a 1 way trip, so the supplies are for the return trip, and for any time spent in orbit. I'm also going to leave 1 Kerbal awake at all times to help drive my ship because I don't have a coms network working that far out so probes wont work. I am going to use the rcs on the main ship to help mechjeb not use as much LF (I think I have enough to get to where I am going but I'm not going to take chances),as well as fueling EVA packs (I use an eva fuel mod). The big tanks are emptied of oxidizer, but I could not find any round fuel tanks with just LF in them. As for the getting to orbit part I plan on just hyperediting it into a stable orbit around Kerbin to save time and the need to go through the atmosphere.

[Zeiss Ikon]

@Harry Rhodan said everything that came to mind immediately when I looked at your images.  Other question I have is why you're building this in the SPH when it's pretty clearly intended to be launched vertically?  Click launch from there, the game will put the craft on the runway, at which point it'll break from its own weight.

You'll have the launch that lander separately; there's no way it'll stay docked through max-Q or with more than 1 G trying to disconnect the docking port.  Once its mounted, I don't know how you'd keep the ship in line during maneuvers.

FWIW, I haven't ever played with life support, but the two missions I've sent interplanetary (one Duna flyby, and one Gilly landing) were done with ordinary chemical rockets, single launch, and had I waited for a good return window from Eve, I could have completed that mission in less than two years.  Same for the Duna flyby, except I only had enough fuel (in two orange tanks) to get back to Kerbin by using a gravity assist at Duna to get an orbit that would intercept after two or three circuits.

[nascarlaser1]

36 minutes ago, Zeiss Ikon said:

@Harry Rhodan said everything that came to mind immediately when I looked at your images.  Other question I have is why you're building this in the SPH when it's pretty clearly intended to be launched vertically?  Click launch from there, the game will put the craft on the runway, at which point it'll break from its own weight.

You'll have the launch that lander separately; there's no way it'll stay docked through max-Q or with more than 1 G trying to disconnect the docking port.  Once its mounted, I don't know how you'd keep the ship in line during maneuvers.

FWIW, I haven't ever played with life support, but the two missions I've sent interplanetary (one Duna flyby, and one Gilly landing) were done with ordinary chemical rockets, single launch, and had I waited for a good return window from Eve, I could have completed that mission in less than two years.  Same for the Duna flyby, except I only had enough fuel (in two orange tanks) to get back to Kerbin by using a gravity assist at Duna to get an orbit that would intercept after two or three circuits.

Thxs! I am not even going to try to fly that thing to orbit. I am using hyperedit to teleport it up to a stable orbit and fly it from there. Tomorrow I'll add some struts to the girder to try and keep it stable. I will spawn it on launch pad however to keep it from breaking apart (didn't realize that could happen.

[Zhetaan]

I suggest either making better use of DeepFreeze or using more of what USI-LS as to offer by adding either a cupola or a Hitchhiker.  I don't know why you say you don't have space for DeepFreeze resources; you seem to have plenty of space on that giant fuel tank.

If USI-LS (and not MKS) has the 60% strap-on recyclers, then take those, too.  They'll save you more than their mass in supplies even if you only keep your Kerbals awake at Duna.

Definitely put that lander somewhere in-line with the rest of the craft.  Look at the centre of mass and centre of thrust indicators to get an idea of what I mean; if the vector for centre of thrust does not point in line with the centre of mass, then you will spin out of control.

You ought not to need more than one hundred units of monopropellant for every docking manoeuvre you will ever do with this craft.  Put it all on the lander and ditch the lander in orbit when you're done; then you won't have to carry it home.  The same holds for oxidiser; the lander is the only thing using it, so put it all on the lander, and any extra can remain with it.

You don't need the nuclear waste containers unless you intend to reprocess it or need to recover it for some reason.  I can't think of one; consider losing the dead weight.

Edited November 24, 2017 by Zhetaan

[nascarlaser1]

22 minutes ago, Zhetaan said:

I suggest either making better use of DeepFreeze or using more of what USI-LS as to offer by adding either a cupola or a Hitchhiker.  I don't know why you say you don't have space for DeepFreeze resources; you seem to have plenty of space on that giant fuel tank.

If USI-LS (and not MKS) has the 60% strap-on recyclers, then take those, too.  They'll save you more than their mass in supplies even if you only keep your Kerbals awake at Duna.

Definitely put that lander somewhere in-line with the rest of the craft.  Look at the centre of mass and centre of thrust indicators to get an idea of what I mean; if the vector for centre of thrust does not point in line with the centre of mass, then you will spin out of control.

You ought not to need more than one hundred units of monopropellant for every docking manoeuvre you will ever do with this craft.  Put it all on the lander and ditch the lander in orbit when you're done; then you won't have to carry it home.  The same holds for oxidiser; the lander is the only thing using it, so put it all on the lander, and any extra can remain with it.

You don't need the nuclear waste containers unless you intend to reprocess it or need to recover it for some reason.  I can't think of one; consider losing the dead weight.

Thank you! I completely forgot that I could attach them to the engines fuel tanks. I am using the smaller of the inline recyclers. I have 1 behind each engine. I will try and rearrange the lander so that it is more inline with the rest of my ship. perhaps I will strap it to the nose and move the greenhouse somewhere else. I have already dumped all oxidizer off the ship except for what's in the lander, I mostly use the big tanks because I liked how they looked. I will ditch some of the oxidizer on the main craft, but I plan on leaving some so mechjeb can use RCS for any minor corrections without burning my LF. I did not realize that I would not need the nuclear waste containers (I've never used the nuclear reactors before, only the containers) so I will ditch those as well.

[Aegolius13]

17 hours ago, nascarlaser1 said:

The big tanks are emptied of oxidizer, but I could not find any round fuel tanks with just LF in them. As for the getting to orbit part I plan on just hyperediting it into a stable orbit around Kerbin to save time and the need to go through the atmosphere.

I would  consider either changing your design to make use of the stock LF tanks (e.g, Mk 1 or Mk 3), or pick up a mod that lets you switch fuel contents or includes LF tanks in your desired form factor.  Nukes give up a decent chuck of their efficiency if you have to drag around the dry weight of empty oxidizer tankage.  It's a big pet peeve of mine that stock KSP gives you a LF-only engine designed for space, and then does not provide any space-oriented parts to actually use it.

Your lander looks like it has a lot of... stuff attached to the skin. Not sure what all of it is, e.g., the green stuff must be from a mod.  You can get away with this to some extent on Duna since the atmosphere is thinner, but drag does add up.  If you can cut down on drag, you might be able to lose the fins on the lander and save a little more mass.

The Poodle seems like it might be a bigger engine than you need for the lander  - do you know what its local TWR is?  My standard Duna lander is a little lighter than that (uses the Mk 2 lander can), but it uses one Terrier.  Other options might be 2 Terriers, a cluster of Sparks, or a Dart.

[nascarlaser1]

38 minutes ago, Aegolius13 said:

I would  consider either changing your design to make use of the stock LF tanks (e.g, Mk 1 or Mk 3), or pick up a mod that lets you switch fuel contents or includes LF tanks in your desired form factor.  Nukes give up a decent chuck of their efficiency if you have to drag around the dry weight of empty oxidizer tankage.  It's a big pet peeve of mine that stock KSP gives you a LF-only engine designed for space, and then does not provide any space-oriented parts to actually use it.

Your lander looks like it has a lot of... stuff attached to the skin. Not sure what all of it is, e.g., the green stuff must be from a mod.  You can get away with this to some extent on Duna since the atmosphere is thinner, but drag does add up.  If you can cut down on drag, you might be able to lose the fins on the lander and save a little more mass.

The Poodle seems like it might be a bigger engine than you need for the lander  - do you know what its local TWR is?  My standard Duna lander is a little lighter than that (uses the Mk 2 lander can), but it uses one Terrier.  Other options might be 2 Terriers, a cluster of Sparks, or a Dart.

thanks! I am right now working on my ship using everyone's suggestions. The little green bags on the lander are from my life support mod. They are mostly there incase I mess up the landing and my kerbals have to stay for longer then 2 days on the surface (the current planned time on Duna's surface). I don't know the TWR of the lander right now because my game is still loading, but I will find out as soon as possible*. I will also remove some of the fins and perhaps only have 2 (they are there for the return to orbit trip, not the actual landing.

 

* Edit: the landers current TWR without modifications is 1.28 (2.13). Lander's TWR with 2 of the fins removed is 1.28 (2.14). readouts are from KER

Edited November 25, 2017 by nascarlaser1

[nascarlaser1]

Here is my new and improved version of the ship!

Thank  you for your help guys!

https://imgur.com/a/9gZGd

[Harry Rhodan]

1 hour ago, nascarlaser1 said:

I will also remove some of the fins and perhaps only have 2 (they are there for the return to orbit trip, not the actual landing.

Two fins are absolutely useless because they can only stabilize you in one axis.

I don't want to sound too judgemental but this and your other threads pretty much look like you want to achieve something with a whole lot of mods while never having mastered or learned most of the basics like stability or manouvers beforehand.

[nascarlaser1]

52 minutes ago, Harry Rhodan said:

Two fins are absolutely useless because they can only stabilize you in one axis.

I don't want to sound too judgemental but this and your other threads pretty much look like you want to achieve something with a whole lot of mods while never having mastered or learned most of the basics like stability or manouvers beforehand.

thxs for explaining fins to me., I will make sure to remove them later (not playing ksp right now) .  You are right. I have gone to the Mun and minimus in pure stock and modded, but I have never gone farther then that (stock craft or modded) without using hyperedit to get me into orbit around duna (I've been testing the lander using hyperedit to make sure it doesn't explode 100% of the time, only 10% of the time.

[Rocket In My Pocket]

Some honest criticism:

It's very large for what it's doing, especially considering you are going to hyperedit it into space, so there isn't a lifter section. A 5 Kerbal ship + 3 person lander is going to be on the big side sure, but you've built a monster! I think if you lose a lot of the fuel tanks, and switch to lighter engines you'll see that while it get's smaller and lighter, your Dv will most likely actually go up.

As others have suggested I think it would benefit you to "get back to basics"  and work on your fundamental rocket building skills a bit; not judging you or your play-style though, if you like em' big that's all fine and well. If it works, it works after all.

[nascarlaser1]

30 minutes ago, Rocket In My Pocket said:

Some honest criticism:

It's very large for what it's doing, especially considering you are going to hyperedit it into space, so there isn't a lifter section. A 5 Kerbal ship + 3 person lander is going to be on the big side sure, but you've built a monster! I think if you lose a lot of the fuel tanks, and switch to lighter engines you'll see that while it get's smaller and lighter, your Dv will most likely actually go up.

As others have suggested I think it would benefit you to "get back to basics"  and work on your fundamental rocket building skills a bit; not judging you or your play-style though, if you like em' big that's all fine and well. If it works, it works after all.

ok thanks! I built big because I'm never sure what will actually get the job done... to get to the mun I need a mk2 booster and transfer stage, and an mk1 lander/return craft so.... yeah... I tend to over compensate where possible . I will make a second version of the ship (for easier comparison)  and change some of the engines and fuel tanks. What would be your recommendation for a smaller engine/fuel tank combo on the main shuttle?

[Rocket In My Pocket]

7 minutes ago, nascarlaser1 said:

ok thanks! I built big because I'm never sure what will actually get the job done... to get to the mun I need a mk2 booster and transfer stage, and an mk1 lander/return craft so.... yeah... I tend to over compensate where possible . I will make a second version of the ship (for easier comparison)  and change some of the engines and fuel tanks. What would be your recommendation for a smaller engine/fuel tank combo on the main shuttle?

Hard to say without re-designing the whole craft but nukes are fairly heavy engines all by themselves, maybe just try cutting back on the number of nukes and the fuel you are carrying first. Use a bi-coupler or a tri-coupler to make a cluster of them at the rear instead of having those huge out board pods.

[Aegolius13]

7 hours ago, nascarlaser1 said:

* Edit: the landers current TWR without modifications is 1.28 (2.13). Lander's TWR with 2 of the fins removed is 1.28 (2.14). readouts are from KER

Is that with the default Kerbin reference on KER?  Since Duna's gravity is lower, your TWR will be correspondingly higher - you can use the button at the top that says "Body" to check on other planets/moons.

If 1.28 is your starting TWR on Kerbin, it's probably almost 4 on Duna owing to the lower gravity.  You can generally launch at higher TWRs on Duna than on Kerbin since the air is thinner.  But you could likely get by on a smaller engine if you're looking to trim down weight.

(Note also that engines like the Poodle take a tiny ISP hit when on Duna's surface since there's an atmosphere.  But it's thin enough they still outperform atmospheric engines). 
 

Edited November 25, 2017 by Aegolius13

[Laie]

18 hours ago, nascarlaser1 said:

Here is my new and improved version of the ship!

Much better.

Something noone has bothered to mention so far, your departure TWR of 0.16 is a bit on the low side. Not overly problematic for going to Duna, but as you say that this will be your first interplanetary mission, I'd like to ask: do you know about periapsis-kicking?

[nascarlaser1]

2 hours ago, Laie said:

Much better.

Something noone has bothered to mention so far, your departure TWR of 0.16 is a bit on the low side. Not overly problematic for going to Duna, but as you say that this will be your first interplanetary mission, I'd like to ask: do you know about periapsis-kicking?

no, I don't. My current plan for hitting duna includes letting mechjeb set up the route and executing it by hand, and if mechjeb somehow manges to mess that up (which it does quite often when bringing large payloads to the Mun) I will just burn till my orbit intersects with duna, put my Kerbals to sleep  with deepfreeze, and wait the years until I get an intercept (my biggest issues in the past of doing this was my Kerbals would run out of snacks while waiting for an intercept, but now that I can freeze them that's not a problem for me).

Edited November 26, 2017 by nascarlaser1