Jump to content

If I ever make it back from Eve

Reinhart Mk.1

By Reinhart Mk.1
in KSP1 Discussion

 Share

Recommended Posts

Foxster

Foxster

Posted
Posted (edited)
3 hours ago, Reinhart Mk.1 said:

Okay so I'm sorry for the bad mic quality/volume (and language... it's frustrating ;.;) but here's my NEW design which could've maybe worked with more reaction wheels IDK. Trying a new one with less vector engines but the aerospike ones don't seem to be cutting it. I KNOW I'm getting close...

 

https://www.youtube.com/watch?v=zNTjfkpSw_k

also uhhh idk how to embed either i'm sorry :(

That looked like it was Aerospikes only, right? If so then the reason it is falling over is that you want an engine with gimbal in there too. So a Vector in the middle and a bunch of Aerospikes around it. 

You also have to dump all the chutes, ladders, etc. before taking off and get a nosecone on the front, otherwise you are going to be losing huge amounts of dV to drag as well as making it even more unstable. 

Edited by Foxster
Link to comment
Share on other sites
HvP

HvP

Posted
Posted (edited)
3 hours ago, Reinhart Mk.1 said:

Okay so I'm sorry for the bad mic quality/volume (and language... it's frustrating ;.;) but here's my NEW design which could've maybe worked with more reaction wheels IDK. Trying a new one with less vector engines but the aerospike ones don't seem to be cutting it. I KNOW I'm getting close...

 

https://www.youtube.com/watch?v=zNTjfkpSw_k

also uhhh idk how to embed either i'm sorry :(

I'm not experienced with Eve ascent, but I can give some feedback on the design in general. The aerospike engines don't have any thrust vectoring, so you're only relying on your reaction wheels and tail fins to point you in the right direction. The problem is that because your thrust-to-weight ratio is so low (you're barely hovering on takeoff) not enough wind is passing over your fins to give you any control authority there. You could save weight by taking most of the reaction wheels off and replacing at least the middle aerospike with a vector engine to give you more control.

Edit: (ninja'd by @Foxster heh)

Edited by HvP
Link to comment
Share on other sites
KerikBalm

KerikBalm

Posted
Posted

Well, foxster's exploity craft do well here. Eve is a bit like the pre-1.0 ascents: you may actually have to throttle down to avoid excessive drag if you reach terminal velocity (cannot be reached if TWR < 2.0)... that said, a problem with many designs is excessive gravity drag. Eve's high gravity takes a design that would be about 2.5 on Kerbin down to less than 1.5 on Eve. On top of that, the thick atmosphere further reduces thrust of the engines (some more than others, most vacuum engines don't do anything, intermediate engines like the skipper are horrible on Eve). Even Mainsails don't do well. You basically want mastadons, vectors, and aerospikes.

Aerospikes are kind bad too for the lower stages. Even on Kerbin at 1 atm, they only have a 15:1 TWR... eve's gravity reduces that to only 9.2:1. Then the atmosphere reduces it even further.... Its worse than using spider engines or a rapier in closed cycle (the whole way) to launch a payload to kerbin orbit.

Even worse is the poor thrust per node/stack. The thrust to cross section ratio means that to get a decent TWR, your drag goes way up, and thus your terminal velocity comes way down. This is why you want the vector, its thrust/cross section size is by far the best in the game (at least it was, I'm not sure on how the MH engine variant switching factors into this now, but I think they can be quite draggy despite their appearances).

I play on a 3x rescaled game, and Eve is super punishing there. I further modified it to be more venus like... I dropped the gravity from 1.7 to 1.25 G, but then doubled the atmospheric pressure to 10 atms... big mistake... at that density, even Vectors and mammoths have Isp too low to be usable. Aerospikes were the only option... and... good lord did I need a lot of them because each one couldn't lift much fuel...

3x eve was ridonculous

Link to comment
Share on other sites
Foxster

Foxster

Posted
Posted (edited)

Just to confirm that your basic design is fine now and makes orbit no problems. 

I tweaked a couple of things then just to lower the mass a bit...

tk5H14b.png

Using a Vector in the centre means you have more than enough TWR so I lost the first couple of Aerospikes. 

This makes a 100km orbit comfortably for me but if you want a bit more margin then put the Aerospikes back and add some more fuel tankage above the Vector. 

...or to funk it up a bit...

B0PuxTu.png

 

 

 

Edited by Foxster
Link to comment
Share on other sites
StrandedonEarth

StrandedonEarth

Posted
Posted

Well, if you have Making History (which includes the extendable docking port) then the Wolfhound (even post-nerf) makes a fantastic upper stage engine 

Not sure why one would need fins and a Vector. That's just extra drag in the Evian soup.

I had a massive two-man Eve vehicle, that landed fully fueled. And yeah, ditch anything you don't need for the ascent.

Link to comment
Share on other sites
Laie

Laie

Posted
Posted
7 hours ago, KerikBalm said:

The thrust to cross section ratio means that to get a decent TWR, your drag goes way up, and thus your terminal velocity comes way down. This is why you want the vector, its thrust/cross section size is by far the best in the game (at least it was, I'm not sure on how the MH engine variant switching factors into this now, but I think they can be quite draggy despite their appearances).

Nah, the Vector can't be beat in that game. MH or not, no other engine comes even close in thrust-to-cross-section. And it's among the most efficient to boot. Hold on, I did a thing a while ago...

eve-isp-x4.png

  1. top left: ISP, simple enough.
  2. top right: burn time you get if you load down an engine with as much fuel as it can carry (TWR=1, includes mass of tanks)
  3. the impulse you get out of a maximally-fueled stack. That is, take engine X, load it up with fuel until TWR=1, burn it until empty. How many kN*s of thrust will come out?
  4. The same, but divided by engine thrust. The unit would be seconds, and while I don't quite know what it means, I take it as a kind of Eve-specific impulse that somehow mashes in TWR.

I didn't include the Vector, but it's ISP is identical to the Mammoth and the TWR a little worse. You can expect it to be slightly below the Mammoth in 2) and 4).

3) gives you an idea of the importance of TWR. Notice how the Twin-Boar outperforms the Mainsail at any altitude, even though it's ISP is slightly worse? That's simply because it can carry more fuel to burn. Even more pronounced between Rhino and Poodle. And do you notice how the Aerospike sticks to the bottom of the plot?

4) manages to represent my personal idea of an engine's worth quite well, even though I cannot express it's meaning in scientific terms. The Aerospike simply fails to deliver, while the humble Mainsail isn't all that bad. Still worse than the Vector, of course, and once you start to think about the number and size of stacks, it becomes Vector, Vector, Vector.

The one downside of the Vector is it's high cost. If you care about money, you should bring an ISRU kit and don't fret too much about building the smallest possible rocket. When fuel is free, cheap gas-guzzlers become interesting.

Link to comment
Share on other sites
Laie

Laie

Posted
Posted
1 hour ago, StrandedonEarth said:

Well, if you have Making History (which includes the extendable docking port) then the Wolfhound (even post-nerf) makes a fantastic upper stage engine 

Interestingly, it doesn't. The WH is quite heavy itself, and on a last stage, it can easily make up the bulk of the (dry) mass. That's a delta-V killer. If your payload is nothing more than a command pod, or, even worse, a service bay with command chair, you should look for more lightweight engines.

 

Link to comment
Share on other sites
StrandedonEarth

StrandedonEarth

Posted
Posted
35 minutes ago, Laie said:

Interestingly, it doesn't. The WH is quite heavy itself, and on a last stage, it can easily make up the bulk of the (dry) mass. That's a delta-V killer. If your payload is nothing more than a command pod, or, even worse, a service bay with command chair, you should look for more lightweight engines.

 

Well, my upper stage was big and heavy enough that it was able to head back to Kerbin from Eve. It helped that the LV started from about 2km

Link to comment
Share on other sites
purpleivan

purpleivan

Posted
Posted

This beastie made it to a 120km orbit, with about 2000dv to spare. The part making it to orbit was the ship dangling from the docking port in the centre (requirements for a challenge) that weighed 20 tons.

DZCv4Oq.png

Clearly it's all a bit on the big side and is only a theoretical vehicle, given that it wasn't actually flown to the purple planet (Hyperedit) but I'm confident that I could have got it there, based on past experience. But it's fun to club physics into submission :)

Link to comment
Share on other sites
StrandedonEarth

StrandedonEarth

Posted
Posted
29 minutes ago, Reinhart Mk.1 said:

Yeah! My bad, I just use jumpshare for music snippets and stuff so it's just the first one that i used. Can I embed images without it though?

imgur works great, that's what I and a lot of others here use. But the lighting on that screenshot makes it almost impossible to see anything.

Link to comment
Share on other sites
GRS

GRS

Posted
Posted (edited)

GDrXZHy.png

Here's a big one, does direct ascent with over 3400 m/s in 95 km orbit from that altitude, it has a stowed orbital stage with 1 Terrier and asparagus of 6 Sparks for 1 Kerbal.

Edited by GRS
Link to comment
Share on other sites
Superfluous J

Superfluous J

Posted
Posted

Oh and while we're showing off Eve landers, I don't have a pic but below is my video for Evepollo. I land on Gilly, fill my tanks with ISRU, then land on Eve without any heat shields by slowing down with all the fuel I'd gotten from Gilly. Then I fill with ISRU again at Eve and launch back to space.

Eventually.

After many failed attempts.

 

Link to comment
Share on other sites
GRS

GRS

Posted
Posted (edited)

One day, i'll be making a bigger one to get a Kerbal to Eve and back, with 3000 5000 ore units from Eve to Gilly in Direct Ascent style, a hopefully good way to make Big rockets (i'm interested in big rockets and that'll be another installment of Centurion Rockets, that large Eve lander is an installment of Centurion Rockets, 3rd largest by now with nearly 6000 total mass, only 2 tons below the 2nd), i'll be doing that after my Ultimate Challenge, the Smaller Eve Lander (Name : Grizzly Reaper) will take part in my Ultimate Challenge, also just saying, @Reinhart Mk.1, looks like you're older than me (i'm 17).

Edited by GRS
Link to comment
Share on other sites
Reinhart Mk.1

Reinhart Mk.1

Posted
  • Author
Posted
17 minutes ago, GRS said:

looks like you're older than me

yessur 27, brain functions like a 9 year old still

1 minute ago, I_Killed_Jeb said:

land vertical rocket landers on Eve without cheesing reloads

9 times out of ten i cannot even reload a save inside the atmosphere on landing or below it, SOMETHING will explode ;.;

Link to comment
Share on other sites
GRS

GRS

Posted
Posted (edited)
1 hour ago, Reinhart Mk.1 said:

You've made me waste both this weekend and last weekend but tomorrow I WILL land and return from the violet HELL that you call a surface, Eve. Feel free to share any of your failed Eve missions here. ;.;

Hyperedit is your best friend for testing Landers, i lost 3 months of useful KSP advantage just to make that direct ascent lander safe from copyright issues, use some advices like "1 FL T400 for upper stage" if you rely in Dockable Landers, you may start to love Eve once you're used with it, even mess up with it, like Eve SSTO Lander things, i know you can do it. :):):)

Edited by GRS
Link to comment
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.

×
 Share
Go to topic listing
×
×
  • Create New...