Optimal Architecture Comparison Challenge I: Mun

[Death Engineering]

So, by the definition of the 'no-clipping not even what the editor allows' rule, this would be illegal? Not a fan of that rule. I'm out.

edit: As would this S1B-style first stage? Was planning on doing entries across all mission profiles, but ....

It's a pity, as the concept of comparing each mission is a fascinating idea.

Edited February 2, 2014 by Death Engineering

[MarvinKitFox]

No, not on this challenge. The point here is to evaluate the strategic values of each architecture, not maneuver node production skill. Cool as free-return trajectories are, the real Apollo only used them on Apollos 8, 10, and 11. Okay, and then 13 once everything went to hell

So, only 4 of the 8 moon missions? Very rare event, that!

[Headhunter09]

So, only 4 of the 8 moon missions? Very rare event, that!

Ah yes, good old sarcasm. Witty!

[PLAD]

Hello, I just joined and can't seem to post pictures until I've got three posts but I have really enjoyed comparing the different architectures for Munar land and return mission. Here's my take:

The direct mission is far superior to the MOR mission for the delta-V's involved. Numerobis looked this a few pages back. My first two entries use the one-man capsule, with one direct mission (requiring about 2800 m/s from LKO to Mun and back to Kerbal) and one using the same capsule with a 1-man probe for landing, which takes about 1380 m/s from the carrier. The mass of my direct capsule and stage in the LKO parking orbit is 3.44 tons. The mass of my MOR mission at the same point is 4.53 tons. Why so much more? the lander has to have a 1-man pod (.6 tons), docking port .02), motor (.1) and the fuel for a dv of 1380 ( I used the .5625 ton tank since for the dv needed a bit more 4 of the little toroidal tanks) for a total mass of not less than about 1.3 tons. Not having to land saves the carrier one .5625 tank, but you have to add a docking port, 3x of the attitude rockets (total .15t), and one monopropellant tank (.235) so you only save about .1 ton. Weight increase at LKO: about 1.2 tons, MOR can't win.

For chuckles I ran the numbers and I think the MRO would break even if the lander weighed 430Kg dry +220Kg fuel=650Kg. Lighter than this and MRO wins. Or if the carrier capsule weighed about 800Kg more. Or the lander dv was more than around 3500 m/s instead of the actual 1380.

I hope I'm not too wordy here. I'm itching to attach pictures. Now for my third post...

[PLAD]

Also, I think the winning entry will have 2 Kerbals since you can just add another pod and double the multiplier, but you don't double the mass since things like the motor(s), decouplers, etc. do not have to be doubled. So I did a third design that aims for points.

Hey, I might be able to post now. Let's see:

Did that show? 24.79 tons, 2 Kerbals no aparagus. 16.1?

Tavert's entry is spectacular and I cannot see a way to beat it.

If this shows I'll post the comparison missions. I have screenshots of each mission step, next I have to figure out how to post an album.

[Bilfr3d]

I do not understand the scoring system. I'd like to have a go (and I'll probably try), but the scoring system is confusing for me. Someone care to explain in simple English please?

[Jasonden]

Sorry about my absence here for awhile!

Clearly this was the heaviest mission, as it required an additional 1.3t of mass for the return craft.

Donfede -- these are awesome!!! I love that you did all 3 so as to allow an apples-to-apples comparison. By the scores it does seem that KOR was better, but only by about exactly the 4th-root-of-2 factor. So possibly an artifact of the scoring system.

[Jasonden]

Since the stock Mun requires so little delta-v to land on and return from, Mun orbit rendezvous is probably never going to be more efficient. I think a closer analogue in terms of delta-v would be a Kerbin-Tylo mission, for which a Tylo orbit rendezvous might make more sense (a mission launching from Eve going to Tylo would be even better).

That's certainly the way that it's turning out. That direct shot in RSS is crazy -- I'll bet you could get to Tylo and back in that thing in stock

[Jasonden]

I'd like to participate, but I'm lost without NovaPunch. Can that mod be allowed?

So, by the definition of the 'no-clipping not even what the editor allows' rule, this would be illegal? Not a fan of that rule. I'm out.

Okay -- I'll change the rules. The point is to be able to compare architectures, though, not mods. So if you get a chance, please try out a couple of the architectures so that we can compare them to each other under each of your design styles. I look forward to seeing what you come up with!

[Jasonden]

So, only 4 of the 8 moon missions? Very rare event, that!

The point was not to say that they were rare, but rather to note that they were not a mission requirement because they weren't used on the later missions.

[PLAD]

Here's my MOR entry:

and the equivalent direct mission entry:

I used the heavier 1-Kerbal capsule with the heat shield for re-entry even though the rules didn't require it. The carrier plus lander was 4.53 tons at 75x75 Km and the direct was 3.44 tons. During the MOR mission I transferred leftover fuel from the lander to the carrier after returning from landing, and then used all of the remaining Monopropellant for 220 m/s of the 284 m/s TKI burn. This made up for the apparent 596 m/s total delta-v deficit of the MOR design.

Both are all stock except for Mechjeb and do not use asparagus.

I have to go and try to attach a whole album in the Noob section now, as I can't seem to get it right.

[PLAD]

Doh, and of course Mechjeb reports the delta-v of the lander stage as if it will be docked to the carrier while thrusting, so the number is too low. Moving fuel from one to the other won't change the total reported dv since they use the same type motor.

[PLAD]

OK here is my final entry, using Kerbin Orbit Rendezvous. It uses the same 2-Kerbal craft as my direct-to-MUN entry.

Javascript is disabled. View full album

It uses 2 identical launchers. I throw my entry to the mercy of the court however, as you will notice that I was about 1.5 m/s short of a clean return to Kerbin. But they made it back to the surface alive!

If I understand the scoring, this would be 100/(13.41+12.95tons) times 2 Kerbals, times 2 (for no aparagus), times 1.189 (the 4th root of 2) = 18.04.

Here is the complete flight for my direct-to-MUN entry, I had previously posted just a picture of the launcher.

Javascript is disabled. View full album

Note that I had 11 m/s left at the end of that mission. You will gather that I don't like to waste delta-V carrying fuel, at least as long as I'm not in the capsule.

Here's my take on direct versus KOR. I think that NASA contemplated EOR when they weren't sure they could build a launcher big enough to put everything in orbit in one go. All KOR does is allow you to use smaller launchers, but at the cost of the extra weight of the docking gear, thrusters, monopropellant, and rendezvous delta-V. As such the two smaller launchers will always weigh more than the one big one. Here it cost me 1.6 tons total launch weight.

I loved this challenge. I'm looking forward to Challenge II. Duna?

[Jasonden]

I throw my entry to the mercy of the court however, as you will notice that I was about 1.5 m/s short of a clean return to Kerbin. But they made it back to the surface alive!

On the contrary, you should be commended for your extraordinary efforts and efficiency in saving that 1.5 m/s dV!

Here's my take on direct versus KOR. I think that NASA contemplated EOR when they weren't sure they could build a launcher big enough to put everything in orbit in one go. All KOR does is allow you to use smaller launchers, but at the cost of the extra weight of the docking gear, thrusters, monopropellant, and rendezvous delta-V. As such the two smaller launchers will always weigh more than the one big one. Here it cost me 1.6 tons total launch weight.

Agreed. However it does seem that at least the relative masses of the fuel and the lander are of the same order, such that it splits into two relatively equal parts. KOR wouldn't make much sense if the fuel required were only half as much as the mass of the S/C, or if it were 4 times as much for instance (though I suppose in the latter case you could break it into 5 launches or launch some fuel with the S/C).

I loved this challenge. I'm looking forward to Challenge II. Duna?

I think maybe so Because of the atmosphere Duna's not TOO much harder than the Mun, so the result may play out similarly. But no need to guess when we can do the experiment!

[LexiSilva]

I'm going to do this tomorrow: I am going to try using actual mathematics (and calculating at school). Just wait for it!

[Jasonden]

and the equivalent direct mission entry:

I think that this may be the wrong picture -- it seems to show a 1-kerbal capsule, not the 2-kerbal lander that you use for KOR?

[PLAD]

Hello Jasonden,

I actually have 4 entries but they are scattered about, and it is ambiguous which one I'm referring to in a given spot. Doh! I posted 2 entries that use the single-Kerbal capsule, one with MOR (26.63 tons, score 7.51) and one direct (19.10 tons, score 10.47) to compare MOR to direct. Then I saw that using two of the lighter single-person pods would get a higher score so I did another direct entry (24.79 tons, score 16.10) this time with 2 kerbals, and finally a KOR entry using that same 2-kerbal landing craft (13.41+12.95 tons, score 18.04) to compare KOR to direct. I can't bring myself to do a 2-Kerbal MOR entry because I know it will be inferior to the direct and KOR entries.

I never included albums of the single-Kerbal MOR or direct flights, (I only learned how to do that last night!) so here's the single-Kerbal MOR flight.

Javascript is disabled. View full album

Here's the single Kerbal Direct flight for comparison:

Javascript is disabled. View full album

Looking back, I should put better titles on my posts.

[Jasonden]

John Houbolt, the NASA engineer whose pursuit of lunar orbit rendezvous won the day and enabled the Apollo program, died today at age 95:

http://bigstory.ap.org/article/nasa-engineer-vital-moon-landing-success-dies?utm_medium=referral&utm_source=pulsenews

[donfede]

John Houbolt, the NASA engineer whose pursuit of lunar orbit rendezvous won the day and enabled the Apollo program, died today at age 95:

http://bigstory.ap.org/article/nasa-engineer-vital-moon-landing-success-dies?utm_medium=referral&utm_source=pulsenews

Thanks for sharing Jasonden,

Salute to those heroes that paved the way into space for us. Here are a couple more links from NASA on Houbolt, one from this week, and another from a decade ago (they even have nice *chalkboard* drawings of the munar mission ).

http://www.nasa.gov/vision/space/features/apollo_lor.html # 2004

http://www.nasa.gov/content/john-c-houbolt-unsung-hero-of-the-apollo-program-dies-at-age-95/#.U1hTiFc6KUk # 2014

[Jasonden]

(they even have nice *chalkboard* drawings of the munar mission )

Speaking of which -- I can figure out most of what's on the chalkboard, but anyone have any idea what the graph is under John's right elbow?