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Lightest Eve lander in 1.2

tseitsei89
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tseitsei89

tseitsei89

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Okay so I know there have been some Lightweight Eve lander challenges before but I haven't seen one in a long time so here goes.

 

Rules that apply for both categories:

 Only allowed mods are informative and visual mods. (And pilot assistant mods for "Anything goes" -category)

No altering physics!

No cheating otherwise also!

No kraken drives or and of that nonsense.

Use of hyperedit is allowed for transfering your craft to Eve and moving the craft to a launching location of your choice. (You can land anywhere you want on Eve's surface and then hyperedit the same ship to a location that you want to launch from.)

You must provide screenshots that show your crafts decent and ascent as well. 

Must be manned. (Kerbal doesn't have to plant a flag or visit the surface so no need for ladders though).

You will start from an unstable Eve orbit so that your starting Ap is >90km and your starting Pe is >0km. You can use any means you want to get the craft there and then whatever mass you have left is your entry score. (I for example used hyperedit to get to 100x100km eve orbit and a small extra stage for deorbit burn that I then decoupled.)

You must reach stable orbit. (Pe >90km).

There will be 2 categories with different rules: A) "Robust and actually usable lander" B) "Anything goes"

Category A) rules:

1. A proper crew pod must be used. So NO lawn chairs.

2. You must take off from <1000m elevation from sea level.

3. No using kerbal's EVA pack for the final circularization. Kerbal must get back to orbit in the pod.

Category B) rules:

1. Land anywhere on Eve and take-off from anywhere on Eve.

2. Other than that do whatever. Use lawn chairs and EVA's and whatever you want.

 

And here is my entry for the A) category to kick things off:

Sub 30t Eve lander

EDIT: Sorry the pics are in a weird order and imgur shuffles them again even if I rearrange them. I dunno why. But you can still see what is going on by reading the descriptions :)

Edited by tseitsei89
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Foxster

Foxster

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I've remade your craft and I've failed miserably at reaching orbit with it. 

There doesn't seem to be nearly enough dV.

Also the dV numbers seem to change oddly between screenshots. And the total dV available when you land it with HE is just around 2000m/s - presumably you used a lot for re-entry and landing - where did the fuel to get to orbit come from?

What's the flight profile like? What altitude did you start your gravity turn etc? How did you de-orbit it with just one engine and with a heatshield attached to that?

I have tried very similar craft to this lots of times and could never pull it off - so well done if you have. 

Edited by Foxster
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tseitsei89

tseitsei89

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20 minutes ago, Foxster said:

I've remade your craft and I've failed miserably at reaching orbit with it. 

There doesn't seem to be nearly enough dV.

Also the dV numbers seem to change oddly between screenshots. And the total dV available when you land it with HE is just 2045m/s - presumably you used a lot for re-entry and landing - where did the fuel to get to orbit come from?

What's the flight profile like? What altitude did you start your gravity turn etc?

I have tried very similar craft to this lots of times and could never pull it off - so well done if you have. 

The pics are in a retarded order and I don't know why and I don't know how to fix it. So that might be confusing...

 

But I'll try to answer your questions:

I used absolutely zero fuel to land. Just atmosphere to slow me down until it's safe to open the chutes and throw away the heatshield.

The reason why dV numbers are changing is (I think) that KER calculates dV for current ISP (or maybe otherwise weirdly too?) and my ISP on Eve sealevel is definitely quite low. And as you can see on the VAB picture the craft has ~6km/s dV while fully packed and that is exactly the same craft that landed minus the heatshield and 1 decoupler.

Flight profile was straight up with full throttle until your speed is ~180m/s and then start to control the throttle to keep the speed increasing slowly. At somewhere around 8km (and 270-300m/s) start turning until you get your prograde vector to something like 10-15degrees away from vertical and then follow prograde and use your throttle to control how much you tilt. If your time to Ap is about 45-50s when you drop the vector and start the terrier you should be fine.

 

I will try it on another computer with the same version of KSP when I get the chance to see if my install is somehow broken :) 

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Foxster

Foxster

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I'll try to see if I can emulate your flight profile from your description. Around 6kdV still seems pretty low for a <1km launch. I've not achieved it since 1.2 with less than 7kdV, so it looks like you have come up with something new here, which would be great. 

I know that before 1.2 you had to go pretty high (25km+) before turning to avoid heatplosion but things are little less thermally intensive with 1.2, so could be we do need to look at turning earlier now and get away with less dV.

Still curious how you de-orbited. I'm guessing you either used HE or had another stage not shown? That's OK for the challenge you have set but other Eve challenges have required that you start at a circular orbit and that is the mass counted, including all you need to de-orbit, re-enter, land and get back to a circular orbit. Don't know if you want to consider that for parity?

Not sure about KER's dV reading. I don't use it these days as MJ has all the readings I need now. Could be it is showing SL dV as you say or something else. 

Edited by Foxster
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tseitsei89

tseitsei89

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9 minutes ago, Foxster said:

I'll try to see if I can emulate your flight profile from your description. Around 6kdV still seems pretty low for a <1km launch. I've not achieved it since 1.2 with less than 7kdV, so it looks like you have come up with something new here, which would be great. 

I know that before 1.2 you had to go pretty high (25km+) before turning to avoid heatplosion but things are little less thermally intensive with 1.2, so could be we do need to look at turning earlier now and get away with less dV.

Still curious how you de-orbited. I'm guessing you either used HE or had another stage not shown? That's OK for the challenge you have set but other Eve challenges have required that you start at a circular orbit and that is the mass counted, including all you need to de-orbit, re-enter, land and get back to a circular orbit. Don't know if you want to consider that for parity?

Not sure about KER's dV reading. I don't use it these days as MJ has all the readings I need now. Could be it is showing SL dV as you say or something else. 

Ok I did it again with a completely different computer and got to 100x100km orbit from 700m elevation launch site with 64m/s dV left.

New and more precise flight profile:

1. Full throttle until speed is 220-230m/s

2. Throttle down so that you will be at around 270-280m/s when at 6km.

3. At 6.5km start turning so that you are about 10-15degrees from vertical once you reach 7.5-8km and click prograde on SAS.

4. Now control the throttle so that your speed is just being maintained or only slowly increasing.

5. When you are around 40 degrees from vertical increase throttle significantly to gain speed. This way you should get your time to Ap to be about 46-50s when the vector runs out of fuel.

6. Immediately start the terrier and burn to prograde with full throttle until your Ap is above 90km.

7. Coast to Ap and circularize.

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Foxster

Foxster

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I've tried a few more times but keep coming up 200-300 dV short, which is not huge. I'll keep trying. 

My feeling is that the difference with 1.2 is not down to changes to engines or tanks etc but that Eve is a tad more forgiving and we can fly a profile to orbit that would have seen the craft burn up before 1.2. Might also be a bit less drag at mid/high altitudes. 

Edited by Foxster
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tseitsei89

tseitsei89

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14 minutes ago, Foxster said:

I've tried a few more times but keep coming up 200-300 dV short, which is not huge. I'll keep trying. 

My feeling is that the difference with 1.2 is not down to changes to engines or tanks etc but that Eve is a tad more forgiving and we can fly a profile to orbit that would have seen the craft burn up before 1.2. Might also be a bit less drag at mid/high altitudes. 

Yes I think you are correct because I got very close to blowing up at one point and had to ease the throttle (while on terrier stage) to keep the nosecone and pod from exploding. The nosecone temperature was something like 30-50K below the critical temperature according to KER at hottest point.

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tseitsei89

tseitsei89

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@Foxster

I downloaded a screencapturing software and got the ascent on video just to show that it is possible. :)

https://www.youtube.com/watch?v=onABiPxvs-o&feature=youtu.be

103x100km orbit from 690m starting point

Here I just edited the same craft (with no heatshield) to eve surface and got off from there.

And as to how I deorbited was I just slapped a decoupler FL-100 tank and a terrier on the back of the craft, did the deorbit burn and decoupled those parts. ANd IMO it is quite stupid to count those as part of your lander for 2 reasons:

1. You could easily deorbit the lander with your transfer stage decouple and then accelerate the transfer stage back to stable orbit.

2. If you count the deorbit stage in it becomes a game of patience since you can just start from 90 001x90 001m orbit, burn 2m/s and then just wait a long time and your craft will land :P Doesn't sound that fun to me...

EDIT: I actually realized that I probably need to add one more rule since now it would be allowed to just drop landers straight down to Eve from 90km with 0m/s orbital velocity and that would probably make heatshields unnecessary and I still want to see crafts that can actually survive proper re-entry...

Maybe something like "Your starting point (where the mass of your entry is calculated) must have an Ap of >90km and Pe >0km". That would simulate the situation after a normal deorbit burn.

Edited by tseitsei89
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Superfluous J

Superfluous J

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13 hours ago, Signo said:

So now my fiery mistress is just "kerbin on steroids"?

No she's still the nastiest planet to land on and return. I've had plenty of deathsplosions coming down and plenty more failed launches by a few scant hundred m/s, just like in earlier versions :D

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tseitsei89

tseitsei89

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1 hour ago, Signo said:

I did not have the chance to try yet in 1.2.1, however that possible profile ascent smells SSTOish.

I'm pretty sure it is impossible from that altitude. Just did some quick tests and I can't even get 5km/s dV while still keeping atmospheric TWR over 1...

But from higher point probably quite doable.

BTW does anyone know the coordinates for Eve's highest point?

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IncongruousGoat

IncongruousGoat

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2 hours ago, tseitsei89 said:

BTW does anyone know the coordinates for Eve's highest point?

No, but here's a map with a red dot on the approximate location of the mountain in question:

LeETrWB.png

Also, I'm going to have to throw together an Eve lander for this. Haven't been to Eve since 1.0.5, and for reasons beyond me I miss the purple rock.

Edited by IncongruousGoat
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Ragingdonut

Ragingdonut

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20 hours ago, Foxster said:

I've remade your craft and I've failed miserably at reaching orbit with it. 

There doesn't seem to be nearly enough dV.

Also the dV numbers seem to change oddly between screenshots. And the total dV available when you land it with HE is just around 2000m/s - presumably you used a lot for re-entry and landing - where did the fuel to get to orbit come from?

What's the flight profile like? What altitude did you start your gravity turn etc? How did you de-orbit it with just one engine and with a heatshield attached to that?

I have tried very similar craft to this lots of times and could never pull it off - so well done if you have. 

Oh dear god... It's you from the Suicide Scientist mission...

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