Kergarin
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Posts posted by Kergarin
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34 minutes ago, sevenperforce said:
Just tested and at 660 m over Dunian SL the Ant already has a higher Isp than the Spider, so there's no reason to use a Spider. Paradoxically, the Spider has a slightly higher TWR ratio at SL because it is closer to its maximum Isp than the Ant, but it's a negligible difference.
That's true, dunas thin atmosphere is almost like vacuom, even at the ground.
Besides from this, I think we are coming to that point where we have to figure out dunas highest equatorial mountain, to minimize the drag problems.
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2 minutes ago, sevenperforce said:
I tried clustering Ants because they have higher Isp than the Spiders but ended up with a really anemic TWR. That approach did allow for parallel mounting, though, which meant I could use the monoprop in parallel and add mono drop tanks. I may revisit.
I'm actually working on onion and asparagus staging using ants and spiders. Looks verry promising until now. Might squeeze out 0.1t
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37 minutes ago, sevenperforce said:
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Playing around with a Juno-based first stage but no luck so far.
The panther could also be interesting. That's still on my list.
I'm playing around with your monoprop idea on the pod, but still ending up heavier. (I won't post this as my entry, if it succeeds, since it's your idea)
The can always runs into some barrier around 200-240m/s in dunas atmosphere, where drag becomes bigger than thrust, while the pod blasts throug it with 500 and still accelerates.
Actually I'm trying smaller engines on the lander, the Spark is heavy and gives a twr >4 which is not really needed.
11 minutes ago, GRS said:@Kergarin, not bad for some
oldman with little tech time, wish i'm as good as you in small stuff like that...Thanks
actually I'm on holiday, so I can spend a little more time They key in small things is picking the right engines. Most just use too heavy ones. U usually have to pick an engine one diameter smaller than the ship for medium g landers and transfer stages.
For example the Terrier seems to be the right choice for 1,25m rockets, as it's the correct size and has a verry good ISP.
But that's wrong. It is 5 times as heavy as the Spark and 25 times heavier than the spider. Especially the Spark has a verry good twr and can lift much heavier payloads than expected.
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9 hours ago, sevenperforce said:
I'll have to go back to that model and look it up later. IIRC, though, it was:
- Lander can full of monoprop
- Single linear RCS thruster
- Two small solar panels
- Cubic strut and small chute
- Docking port jr
- Two tiny-sized decouplers
- Smallest 1.25m tank
- Spark
- Roundified prop tank
My pod lander is 1.705t wet and with chute, and 0.82t after decoupling chute, engine and fueltanks.
Your can seems to be around 1.6t. my cans also ended up in this area. But the problem I'm facing besides the fairings drag is the fairings weight. I need around 0.2t extra fairing to cover it, ending up actually heavier at launch.
We save a little xenon for the transfers and Ike landing, but that would be less than 0.01t.
But I'm still trying to optimize both.
Question: what about making history parts?
2 hours ago, jinnantonix said:Kergarin wrote
Too good. I spent 4 hours today testing designs. I kept coming back to your solution.
Thanks! Yes, also my other solutions all perform worse.
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1 hour ago, sevenperforce said:
I suppose I could loft the can without any monoprop in it, but it seems a waste to leave that capacity untapped.
I also converged to a Whiplash+Spark combo rather than a Rapier, but I managed to use the same spark for Duna ascent that I used for Kerbin. Gotta love those roundified tanks. I think my problem remains aerodynamics during Kerbin ascent.
That's also an interesting idea. What's your landers weight wenn starting the descend to dunas surface?
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That's what i got actually:
5.794 tonsthat Ike Landing was absolutely unintended.
I just realized how much dv i had left in Duna Orbit, and gave it a try.
Combining a Whiplash first stage with a Spark turned out to be more efficient than an rapier.
The solar panels are mounted asymetrical to always ensure all 4 can get into direct sunlight
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5 minutes ago, herbal space program said:
Once I changed intakes and made it all into one stack, all my problems pretty much went away. This is what it looks like now:
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As you can see, the wings and Sepratrons are long gone now, since it is now light and aerodynamic enough to scream into the sky without such help. Getting it to reach almost 1500 m/s on just the air-breathing Rapiers also allowed me to dispense with the extra Spark engine, reducing weight even more. This version has 4.2 km/s on orbit, with about 1300 of it on the Spark, so I believe it should be able to do Ike. A previous version with one less T100 tank still had enough to do Duna alone and came in around 5.8t. Anyway, I still don;t think I'll beat yours, but at least it's respectable!
It comes really close, only a few details in stages and so are different.
I will be releasing a preview of mine in a few minutes.
There is still some small margin in my desing, by using less batteries and solar panels and tweaking fuel even more. But this would be pain to execute.26 minutes ago, sevenperforce said:I used monoprop and a single linear thruster for circularization of the module, since it contains its own monoprop reserves.
I'm using the mk1 can rather than the pod for mass reasons but aero problems are keeping me right around 6 tonnes.
Is using nonprop efficient on your design? In most of my designs, the weight of just one linear thruster and nonoprop took more dv than it gave.
I also did not give up the can version. Still working on both to see how low we can push this.
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32 minutes ago, herbal space program said:
I'm currently at just under 6.4t with something that should be able to do both Duna and Ike, landing the pod on both bodies and then Kerbin in the end. For me the breakthrough was twofold: 1) remembering that you can mount the ion engine directly behind another engine, and it still works the same. and 2) Figuring out that the Diverterless Supersonic Intake is total bunk. Not sure now why anybody would ever want to use that part.
Yes, this intake is bad at high speeds and worse at static. A better intake should give the rapier the power to launch without those sepratrons.
An inline mounted ion engine works indeed and makes things easier. But I personally don't do this, as it feels wrong to me.
You could also think about getting rid of the wings, and go for a flat ballistic trajectory as I do.
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7 minutes ago, Johnster_Space_Program said:
for the command seat section, yes you can bail out and land with the kerbal parachute, that's what your supposed to do.
But I'm using a mk1 pod for the tour. Is bailing out for the touchdown at Kerbin ok too?
I have to say, I didn't think about this, as it felt legit, as the Kerbal is well protected and comfortably travelling in the command pod during the entire trip.H e just jumps out at Kerbin in a height of around 1200m, where it is save and close to home
If you say it's not legit, I will start over again
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13 minutes ago, sevenperforce said:
My current version, that lands a capsule on Duna and then returns it to Kerbin by chute, is 6.004 tonnes. I have a version at 5.21 tonnes but can't quite make orbit at Kerbin. I found that using a chute-assisted propulsive landing at Duna took less mass than going pure propulsive, and since I had the chute anyway I might as well repack and use it at Kerbin. I suppose I could attach the chute to one of my ascender's drop tanks and thus save a bit of weight for the Duna LV and transfer stage, but I don't know it would save that much.
I assume you are, like me, using an ion transfer stage and leaving it in low Duna orbit, while using (primarily) biprop for the Duna ascent?
Yes exactly. Ion transfer stage and lf/ox lander. I do a chute assisted landing too, but then drop it before taking of from duna.
Keeping the chute would just require some more xenon, which does not weight that much. But it would be a hell of work to redo it.
the video is cut since days... I'm just waiting for a friend to compose some music. Maybe I should do a preview without it until then.
Also: are wo allowed to repack chutes with pilots in sandbox?
I also tried landing a single stage with biprop and xenon, hoping I would require less heavy biprop and circularize on ions. Also saving some docking ports and maneuvering But this turned always out to be heavier.
Actually I'm using the mk1 pod, which is rather heavy but more aerodynamic (why in the world is Dunas thin atmosphere that draggy?). I had some concepts using the mk1 can at around theoretical 5.2t too, but it has horrible aerodynamics at launch on kerbin due to a massive fairing.
By leaving the pod in duna orbit, going down on a seat, I guess less than 5t would be possible.
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4 hours ago, sevenperforce said:
Question -- if one chooses the command pod version rather than the command seat version, must the pod itself land on Duna, or can you simply use a command seat for the landing and use a pod for the return?
Also, if you use a pod, is there a requirement that the pod itself land on Kerbin or can you bail out and chute down?
I hope at least the second is allowed
Else I would have to adjust it a little...
Edit: Also if the first is allowed, I would have to start over again to get an even lower weight.
I land the pod on Duna, return and reenter in the pod on kerbin, and bail out a few hundred meters above the ground to glide down on the personal chute
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Recorded, surprised myself with something unexpected
, cutted...
and now comes the hardest and most exhausting part of all... Finding music for the video
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Starting now at 5.794t
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This one does Duna and back using a pod with 5.988t wet
Will do the video this weekend
Someone more patient than me could lower this to 5.8xxt using a lot of burns
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Interesting challenge.
You might want to specify if command seats are allowed or only closed pods. This changes minimum weight a lot
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When you try 5 different search phrases for Israels Mun lander, wonder why you can't find anything, and then you realise... That thing is still called moon
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8 hours ago, 4x4cheesecake said:
Uhm...I'm confused now: the title says MK3, your description says MK2
There is a confirmed bug with drag on the MK2 cargo bays, but actually the other way around...less draggy while opened:
It's also on the bug tracker: https://bugs.kerbalspaceprogram.com/issues/20997
Not sure if there is something similar with the MK3 cargo bays...I just know about a difference in buoyancy, depening on the state of the bay.
Sorry, have corrected it. It's mk3
8 hours ago, The_Cat_In_Space said:Have you tried putting a test payload in the bays to see if it makes it better or worse?
Yes. Same issue. Even unstable if the payload moves the com way forward.
1 hour ago, OHara said:You will need to search the bug-tracker for 'cargo drag' and see if anything matches.
They restored its visibility, whether you registered yourself to make reports or not.Some possibilities are #13366 (similar problem on reloading, if the cargo bay is the root part) and maybe #16993 (drag from parts that span cargo bays). Often the bug report tells you an easy way to avoid the problem.
Thanks I will check those out and do some further investigations later.
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Hello,
Stock ksp 1.6.1 with mh.
I have a plane, which is well balanced and flies stable in wet and dry. No matter how hard you try, it won't get out of control.
It's body mainly consists of 2 mk3 cargo bays (one medium, one short).
After I open and close the cargo bays, the planes body creates massive drag, causing the plane to stall, spin, fly backwards.
While this is normal while they are open, the higher drag seems to stay after closing.
Is this a know issue? Could not find anything about this.
The bays are set to opening limits. I would need to check if this occurs without limits too.
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18 hours ago, GRS said:
Up there is a good entry, he didn't get the spot from previous thread like what happened to @Kergarin earlier, but that entry right above me is in fact...above 1.4.
Are you referring to my old attempt for this challenge in 1.0.4? Sorry for the bad video, was my first ever
Burn times of several hours realtime due to the high part count and slow performance back then.
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I gave my litte lowtech Duna plane ist own Video:
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No problem
I guess the hardest part is planning all the transfers between planets and the needed fuel for this in advance.
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39 minutes ago, GRS said:
Any advice for Non ISRU Grand Tours ???
Non ISRU Grand Tour recipe:
Design a lightweight refuelable lander that can get from moho orbit to surface and back. This can do at least everything but Eve, Tylo and Laythe.
Build a disposable Eve lander.
Check if your Eve lander can get from orbit to surface and back on Laythe and Tylo in one piece and then be refuelled. And if this is more efficient than a separate lander.
If yes, you are done. If not build a lander for laythe and Tylo. You could build one that gets to surface and back in one piece at laythe, but which is staged and disposed at Tylo. Laythe is easier, as you can land almost for free due to its atmosphere.
At least one of the above crafts should be able to do duna. This could at best be the lightweight lander, depending on your design. Due to its atmosphere, you can land here also almost for free, while Dunas atmosphere is so thin and gravity so weak, that even small engines can get you back to orbit.
Now you will need something to travel between planets. It's probably a bad idea to take all the needed fuel and the heavy landers with you from planet to planet. You could split your rocket in kerbin orbit into several refuelling pods, sending them directly to where you will need them.
The order also matters. Try to get rid of heavy things early.
Now strip all this together in a big rocket, and you are done
To fullfill the Ultimate Challenge in game contract, I think you will need to do all this using a pod that's dockable to all your landers instead of some command seats. As this contract requires to land the same vessel everywhere.
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I have tested where ese my little rocket can go
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This one is around 0.2 tons in LKO.
Will have to check for the exact weight.
Edit: 0.18t in 75km orbit
actually I'm on holiday, so I can spend a little more time 
Lowest Mass To Duna and Back Challenge
in KSP1 Challenges & Mission ideas
Posted
Would have to measure that. It really feels extremely draggy for such a thin atmosphere, but has almost no impact on vacuum optimized engines.