Mercury and Back

smol

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#1
"Mercury? Never been there."

"Mercury? That's the graveyard of the solar system!"

"Yeah I've been to Mercury... we arrived at that desolate anatmospheric stone and retroburned with our Kolibri. I think we made impact at 5,000m/s. Did I mention we had Unbreakable Parts set to ON?"

I've notice Mercury has a certain allure and foreboding the SFS crowd. How about a nice mission / challenge?

Rules:

a one DLC build and launch manned mission from earth to safe capsule landing on Mercury and then return the capsule safely to earth. No cheats. As ion engines are too OP in 1.5, do it with chemical engines only. Priority is lowest weight launched from earth. Splitting up and refueling with yourself permitted, if you think it would help.
 

smol

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#3
Working backwards, the Mercury orbit to Earth can be done with a kolibri, fuel, capsule, and parachutes. TWR is irrelevant here.

To get from mercury to orbit also requires only a Kolibri (assuming this requires 1,000m/s delta V) and a TWR of 0.4. Since these two stages only require a single Kolibri, I had a hunch and tried combining these two stages Mercury-LmO-Earth stage. It weighed less as one stage:

Code:
Stage Mercury-Earth Report:
  Bill Of Materials
    2 x parachute
    1 x capsule
    1 x Kolibri engines
    20.0 tons tanks
  total weight 25.30 tons; deltaV=3167m/s (>3103); thrust=15.0T; TWR(earth)=0.59 (>0.40); burn time=312s (>309)
Working backwards some more, we will need to travel from LEO to LmO (Trans-Mercury Injection). The deltaV for this is 644 + 17 + 59 + 436 + 1364 + 244, and theoretically could also be done with a Kolibri, but geez this is a deltaV of 6800 now and is getting absurd. The tank size required was also prohibitive, so I left the Trans-Mercury Injection as its own stage. Two stages, actually, as it was more efficient.

Code:
Stage TmI 2 Report:
  Bill Of Materials
    1 x (stage Mercury-Earth 25.30T)
    1 x separator-4w
    1 x Valiant engines
    35.0 tons tanks
  total weight 62.70 tons; deltaV=1915m/s (>1844); thrust=40.0T; TWR(earth)=0.64 (>0.01); burn time=220s (>215)

Stage TmI 1 Report:
  Bill Of Materials
    1 x (stage TmI 2 62.70T)
    1 x separator-4w
    1 x Valiant engines
    80.0 tons tanks
  total weight 145.10 tons; deltaV=1881m/s (>1849); thrust=40.0T; TWR(earth)=0.28 (>0.01); burn time=504s (>498)
The choice of Valiant here must have been a tight fit between the lower ISP of a Kolibri and the higher weight of a Frontier. Interesting.

Next up, a standard optimized two stage to LEO with a 145T payload, assuming deltaV for earth is 3,000, TWR 1.2 on the ground, and TWR 1.0 in the air.

Code:
Stage LEO 2 Report:
  Bill Of Materials
    1 x (stage TmI 1 145.10T)
    1 x separator-4w
    3 x Frontier engines
    135.0 tons tanks
  total weight 298.50 tons; deltaV=1485m/s (>1467); thrust=300.0T; TWR(earth)=1.01 (>1.00); burn time=117s (>116)

Stage LEO 1 Report:
  Bill Of Materials
    1 x separator-4w
    1 x (stage LEO 2 298.50T)
    8 x Frontier engines
    295.0 tons tanks
  total weight 641.90 tons; deltaV=1517m/s (>1515); thrust=800.0T; TWR(earth)=1.25 (>1.20); burn time=96s (>96)
Looks like 8 frontiers on the bottom, and three more on top. Okay, let's build it:

IMG_0100.png


Made it to LEO with some extra deltaV in stage 2 (8.4% in the tank). Great, always appreciate a boost to an injection. If I remember right, I used the rest of stage 2 to expand the ellipse a little (but staying in earth SOI), and on the next pass laid on the Valiant.

As luck would have it, I ran out of gas, dropped stage 3, and performed the landing on a Kolibri. Oops, not sure what went wrong there.

IMG_0099.png


Supposed to have 100% in that tank but only reading 72%. Bad piloting? Incorrect deltaV for deorbiting Mercury? Beats me.

Will I make it home? Well, I can always try making a low Mercury orbit to save some gas, and hope for the best! Orbiting Mercury with a periapsis of 2544 (has to be above 2500 to time warp!).

IMG_0095.png


Accelerate in that transfer window into earth's atmosphere...

IMG_0096.png


Had to try that a couple times because the moon got in way the first few tries. And... home, with a little retroburning.

IMG_0097.png


Woo burned all fuel except 3% in the last tank. I fly smol and TIGHT!!!

IMG_0098.png


These were all Hohmann transfers. I suppose a gravity assist could have saved me some fuel. Anybody else taken astronauts Mercury and back in 1.5?
 

Blazer Ayanami

Space Shuttle enthusiast // Retired Admin
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#5
Anyway, I completed the challenge. As I said, completely Base-Game, without bp editing and overlapping. In another words, this is a rocket any iOS Base-Game player can use.

Total Weight: 442 tons.
Screenshot_20200705-053221.png

The only thing you can point me is that I'm burning the second stage engine, despite Its nozzle is covered, but the challenge didn't required to be realistic.
Screenshot_20200705-053345.png


Anyway, reached LEO
Screenshot_20200705-054002.png


Used a Gravity Assistance from Venus to reach Mercury:
Screenshot_20200705-054426.png


Mercury capture burn:
Screenshot_20200705-054919.png


Landed on the surface of Mercury:
Screenshot_20200705-055354.png


Once again I used a Gravity Assistance from Venus, this time to reach Earth:
Screenshot_20200705-055831.png

(Ignore the debris in Solar Orbit :p)

And back to Earth:
Screenshot_20200705-060349.png

Screenshot_20200705-060558.png


Okay, the rest of the ship broke up, but the capsule and the astronaut survived!

I'll call this a Mission Completed.
 

AstroThis

«★» Dronid «★» // PT
Registered
#7
I never try a land on Mercury because I'm playing on Eternia 1. I'll try, it will be a good experience for me, my first time !!
 
T

TtTOtW

Guest
#9
My "skedonk" refuses to screenshot... Still, I'm nearly back at Earth. Just one more assist...
 
#10
I’d just got my return ready with 41% fuel but managed to blow up my engine ejecting an empty module, hadda back up bit but need to sleep, so tomorrow...if I can make it on 41%
 
T

TtTOtW

Guest
#11
Right. Screenshots are near impossible to get with this Jalopy. But:
Screenshot_2020-07-13-20-47-05.png

So I reached orbit with the core at 14%. S2 almost saw me swing by Venus. 98℅ on S3 at that point. It did all the Graveyard flybys and then was discarded with 140m/s left between a landing and a new grave. The last stage kissed the charred soil ever so gently, and so, the astronaut got tf outta there. Another Venus assist saw him look for a cheap return to Terra with 7.4% hope remaining. A 3% drain got him a gentle re-entry and landing back home.
Screenshot_2020-07-13-19-57-15.png
 

Blazer Ayanami

Space Shuttle enthusiast // Retired Admin
Registered
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#12
Right. Screenshots are near impossible to get with this Jalopy. But:
View attachment 41700
So I reached orbit with the core at 14%. S2 almost saw me swing by Venus. 98℅ on S3 at that point. It did all the Graveyard flybys and then was discarded with 140m/s left between a landing and a new grave. The last stage kissed the charred soil ever so gently, and so, the astronaut got tf outta there. Another Venus assist saw him look for a cheap return to Terra with 7.4% hope remaining. A 3% drain got him a gentle re-entry and landing back home.
View attachment 41699
You used multiple Mercury flybys to reduce your apoapsis?
 

Altaïr

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#15
Going to Mercury using fly-bys has become incredibly difficult with the update... o_O
Venus orbit has been raised in 1.5, so now it's closer to the Earth (if we forget the increased scale factor), but further from Mercury. This and the fact that the Sun is heavier makes it way more difficult to reduce the orbit that way.
I managed to do it, but I needed 7 slingshots overall o_O
That paid off though, I managed to reduce the delta-V requirements by a half compared to a direct burn. If I can design a return trajectory I should be able to design a light mission to Mercury.
 

AstroThis

«★» Dronid «★» // PT
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#16
Personnaly, I don't calculate nothing and doing just like this. No orbit slingshot pr wathever. I go straight away and that's all ;).
I don'r want to past time in calculating complicate things, if I fail, I do another version with little difference and try it. I do that over and over to have just fun and no calculator near to me :p.
I'm just having fun without numbers lol
 

Altaïr

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#17
Personnaly, I don't calculate nothing and doing just like this. No orbit slingshot pr wathever. I go straight away and that's all ;).
I don'r want to past time in calculating complicate things, if I fail, I do another version with little difference and try it. I do that over and over to have just fun and no calculator near to me :p.
I'm just having fun without numbers lol
That's your right and I perfectly understand that! That's the best way to improve at first.
That's how I started, then I tried to do better: I tried different trajectories to see if I could save fuel, if I ended a mission with fuel remaining in the tank I tried to redo it with less fuel, and so on... Until I find the limit.
And that pays off, an optimized mission means I can do it with a smaller launcher, or that I can bring a bigger payload to my destination with the same launcher.
That's a win-win in all cases. :cool:
Now the drawback is that if you really want to optimize you'll have to go into numbers at some point. But you don't have to worry too much about that, some people on the forum made the ugly maths for you, and made some useful tools, so it's not that hard in the end :)
 

AstroThis

«★» Dronid «★» // PT
Registered
#19
That's your right and I perfectly understand that! That's the best way to improve at first.
That's how I started, then I tried to do better: I tried different trajectories to see if I could save fuel, if I ended a mission with fuel remaining in the tank I tried to redo it with less fuel, and so on... Until I find the limit.
And that pays off, an optimized mission means I can do it with a smaller launcher, or that I can bring a bigger payload to my destination with the same launcher.
That's a win-win in all cases. :cool:
Now the drawback is that if you really want to optimize you'll have to go into numbers at some point. But you don't have to worry too much about that, some people on the forum made the ugly maths for you, and made some useful tools, so it's not that hard in the end :)
Thx for this explanation ! When I'll feel that I can't do it better without numbers, I'll lool for that and try to understand that !
 
#20
Super cool comrades, question do you do gravity manoevrous near the moon? 2 good moon gravity manevrous send the vehicle to orbit the sun, fuck it
I’ve been trying to find a moon brake which looks good inside the Earth well but winds up a bit wide of Earth orbit no matter what I do, not sure it can help going to Mercury but I got a couple more options to try later
 
#21
Ok, found my error...

I was thoughtlessly making my Moon encounter on the ‘outside’ of the Earth well, away from the Sun which doesn’t make sense I came to notice;
So I let my craft orbit a ‘couple weeks’ putting the Moon on the Sun side for the encounter
C1FA75F7-3A85-46D7-B546-EAE7F4540230.png
0161E942-DBE7-4A3E-8928-13F7A2D71DB3.png
Making a nice close ‘boost’ from the backside gave me rather a sizable brake instead relative to the Sun
B7AC82E4-2C0B-4417-ADBA-82EF86A0DB49.png
The craft orbit is actually further in from the Earth orbit this way than it was out the other way when I did an intentional boost assist as a control which seems rather odd but I’ll take it
 

Blazer Ayanami

Space Shuttle enthusiast // Retired Admin
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#22
Super cool comrades, question do you do gravity manoevrous near the moon? 2 good moon gravity manevrous send the vehicle to orbit the sun, fuck it
Believe it or not by that's actually unefficient, comrade. What happens is that the Sun is now super heavy (Well, it actually has Its weight in real life), so, to get to Venus using the Moon, you have to power-up the assistance by accelerating near the Moon, which in the end makes you spend the fuel you pretended to save.

Personally, when I go to Venus, I always use direct burn from LEO.
 
#23
Merc5:
D8B61EEB-8B86-4C51-AC1D-610384E081C0.png
B383BF6E-EAB2-4341-B890-7AF35801F1CF.png
45C9DFF8-77E1-4D78-9D5A-15A55F15EA62.png
So I did a Moon assist, seemed to work unless I’m missing something;
Then Venus and Mercury x4 and a 5th maybe pointless for the actual orbital injection

I think this was #2:
F40603A2-56A1-419D-8AAE-53A940B57D5E.png
Terrifying to be sure :D
3EEBDC76-4D47-4FFE-B202-463CA5448067.png
3rd stage didn’t quite make orbit, but close enough, got a spare fuel mod
DAEFEAEA-6130-466F-92AA-99D071672B78.png
341E28EC-EB1A-47F8-A69D-30CBC8D2E57B.png
My finest landing ever, I must have remembered to save;
I made a total first shot suicide burn, just a new mass test, no sweat...but landed like an autonomous program, wow
815E16F3-7604-4F30-8ABF-901A7A8B9A18.png
Refueled, well close enough to make Venus to almost LEO without a mad burn aero brake, should of done Venus twice maybe
7A3FA01B-7EB4-40FC-A3D2-400DC5C70105.png
04C0C7AA-DFA5-46F5-BB43-1A8BC8131881.png
And my fantastic Mercury landing didn’t even register:rolleyes:
 
T

TtTOtW

Guest
#24
Merc5:
View attachment 41768 View attachment 41769 View attachment 41760 So I did a Moon assist, seemed to work unless I’m missing something;
Then Venus and Mercury x4 and a 5th maybe pointless for the actual orbital injection

I think this was #2: View attachment 41762 Terrifying to be sure :D View attachment 41761 3rd stage didn’t quite make orbit, but close enough, got a spare fuel mod View attachment 41763 View attachment 41764 My finest landing ever, I must have remembered to save;
I made a total first shot suicide burn, just a new mass test, no sweat...but landed like an autonomous program, wow View attachment 41765 Refueled, well close enough to make Venus to almost LEO without a mad burn aero brake, should of done Venus twice maybe View attachment 41767 View attachment 41766 And my fantastic Mercury landing didn’t even register:rolleyes:
Lol neither did mine.
 

Altaïr

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#25
Believe it or not by that's actually unefficient, comrade. What happens is that the Sun is now super heavy (Well, it actually has Its weight in real life), so, to get to Venus using the Moon, you have to power-up the assistance by accelerating near the Moon, which in the end makes you spend the fuel you pretended to save.

Personally, when I go to Venus, I always use direct burn from LEO.
I confirm, there's even a strong possibility that you spend more than what you would have saved. From the delta-V map, the difference between an injection towards the Moon and Venus is about 76 m/s. That's really few, and you have to substract from this all maneuvers, corrections, and the boost at Moon level. You'd already be lucky that the benefit is 0 :rolleyes: