The Mun and back Cheapskate Challenge

[ManEatingApe]

5 hours ago, aubranium said:

I couldn't help but try without the Minmus segment. This vehicle came in at 4666 funds. And this time, I didn't even need to use EVA fuel to settle into aerobraking orbit! I'm pretty sure I could get it below 4600 if I drop one of the Oscar tanks and use EVA pack for the last 100 delta-v.

That is some practical progressive penny-pinching. You were also very patient with all the aero-braking passes!

You could potentially save even more funds if you ditched the reaction wheel, battery and solar panel. The gimbal from the Spark engine would still allow you to steer as long as some thrust is maintained.

[aubranium]

On 5/3/2020 at 11:27 AM, aubranium said:

I'm working on a how-to video for YouTube this week.

It didn't end up being a how-to video exactly, but I hope you like it:

 

[aubranium]

On 5/9/2020 at 4:51 PM, ManEatingApe said:

You could potentially save even more funds if you ditched the reaction wheel, battery and solar panel. The gimbal from the Spark engine would still allow you to steer as long as some thrust is maintained.

I was indeed able to do this exactly as you said, and that was almost as hard as the Three Parts to Laythe mission (try navigating to Jool with just engine gimbaling for attitude control). The cost came in under 4k!! I recorded it of course, but I'm exhausted from publishing the short film. Thanks for inspiring me to try it. 

[ManEatingApe]

17 hours ago, aubranium said:

It didn't end up being a how-to video exactly, but I hope you like it:

 

17 hours ago, aubranium said:

I was indeed able to do this exactly as you said, and that was almost as hard as the Three Parts to Laythe mission (try navigating to Jool with just engine gimbaling for attitude control). The cost came in under 4k!! I recorded it of course, but I'm exhausted from publishing the short film. Thanks for inspiring me to try it. 

Love the video! Especially like seeing the evolution and refinement of each design.

[camacju]

This was a fun challenge!

https://imgur.com/a/91ltiPP

I would like to submit in the Reusable category.

This craft consists of a small SSTO booster with overkill engines that I repurposed from another challenge, and a small lander.

Total: 440.16 liquid fuel used, 108.43 oxidizer used
Total cost after recovery: 371.66 funds

This mission was pretty sloppy and I think I could have done better. Some potential improvements are:
(Maybe) Remove the Nerv, make the jet booster smaller, and make the lander bigger - but would this reduce the fuel used? The Nerv is pretty efficient
Tighten the margins - I had fuel left over
Remove the service bay on the SSTO and attach those parts elsewhere
Make the decoupler detach from the lander instead of the SSTO so I don't have to haul it to the Mun and back
Remove the parachute from the lander and use the Kerbal EVA chute
Reduce the lander's battery capacity

[camacju]

https://imgur.com/a/lyjyuh1

This is my submission for the Command Chair category.

This craft uses a probe core for several reasons. First, it's the cheapest reaction wheel. Also, it's more useful for aerobraking, for two reasons. It is a bit wider than 0.625 m, so it occludes better. And it's a control point so I can mount the pilot prone, so she doesn't burn up during reentry.

Cost on launchpad: 3457 funds

This also was a pretty sloppy mission. I flew a terrible ascent profile. I probably could have landed using the second stage with a better one.

[ManEatingApe]

On 10/10/2020 at 5:13 AM, camacju said:

https://imgur.com/a/lyjyuh1

This is my submission for the Command Chair category.

Welcome to the forums and to the challenge! You jump directly to 1st place in the command chair category.
I like the sleek design and clever use of the Okto as an unorthodox heat shield. I'm certain that with a flatter ascent profile some fuel (and hence cost) could be shaved off.

On 10/10/2020 at 12:43 AM, camacju said:

This was a fun challenge!

https://imgur.com/a/91ltiPP

I would like to submit in the Reusable category.

This craft consists of a small SSTO booster with overkill engines that I repurposed from another challenge, and a small lander.

The 2 part re-usable design is a good start. Unfortunately I can't accept this specific design - the nuke clipped into the Rapier breakes the rule on excessive clipping.
But I feel with some tweaks the leaderboard awaits you in this category too...

Edited October 11, 2020 by ManEatingApe

[camacju]

@ManEatingApe Would this design be acceptable?

Edit: Actually scratch this, I'm just gonna redesign the SSTO entirely. This is too draggy

Edited October 11, 2020 by camacju

[camacju]

https://imgur.com/a/nR8DBal

@ManEatingApe I redesigned the SSTO, here's the new mission - 405.99 funds used. I hope the nuke clipped into the precooler isn't too excessive. It doesn't provide any drag benefit since the center of mass is outside the precooler; it's only clipped to make the craft easier to take off and land.

Edit: Also I think I've figured out a loophole in the rules that will allow me to do a mission for practically 0 funds, without mining or refueling

Edited October 12, 2020 by camacju

[ManEatingApe]

21 hours ago, camacju said:

https://imgur.com/a/nR8DBal

@ManEatingApe I redesigned the SSTO, here's the new mission - 405.99 funds used. I hope the nuke clipped into the precooler isn't too excessive. It doesn't provide any drag benefit since the center of mass is outside the precooler; it's only clipped to make the craft easier to take off and land.

Nice work on the entry...you sweep the 1st place spot in the re-usable category too.
2 down...one to go!

21 hours ago, camacju said:

Edit: Also I think I've figured out a loophole in the rules that will allow me to do a mission for practically 0 funds, without mining or refueling

I'm always delighted to see entries involving technical ingenuity and/or great piloting skills. Do make sure to stick to the spirit of the challenge and avoid any rule lawyering as it ruins the fun for other entrants.

[vyznev]

On 10/12/2020 at 8:46 PM, camacju said:

Edit: Also I think I've figured out a loophole in the rules that will allow me to do a mission for practically 0 funds, without mining or refueling

Does it involve a Convert-O-Tron? Because if so, I see it too now, but IMO it definitely violates the spirit of the rules, and arguably their letter too (insofar as, even if you didn't mine it, turning ore into fuel could be considered refueling).

Of course my guess could be wrong. If you've found some other loophole, I'm certainly interested in seeing it.

(IMO, finding clever loopholes in challenges can be fun, even if the entries end up getting disqualified and the rules patched. I forget who first came up with it, but I've always liked the "meta-rule" that if you find an interesting loophole in the rules, you'll earn an honorary mention, and a new rule forbidding what you just did will be added and named after you. )

Edited October 13, 2020 by vyznev

[ManEatingApe]

1 hour ago, vyznev said:

(IMO, finding clever loopholes in challenges can be fun, even if the entries end up getting disqualified and the rules patched. I forget who first came up with it, but I've always liked the "meta-rule" that if you find an interesting loophole in the rules, you'll earn an honorary mention, and a new rule forbidding what you just did will be added and named after you. )

To cater for creative mischief, I've added a Rogue's Gallery section for entries that break the rules. Anything there won't count towards the leaderboard but could earn an honorary mention for especailly inventive or amusing antics.
 

Edited October 13, 2020 by ManEatingApe

[camacju]

https://imgur.com/a/5gIGXFo

Well @ManEatingApe Here is my submission that does not TECHNICALLY break any rule.

I am not mining; all the ore is loaded onto the ship at launch.

I am not refueling; I don't burn any monopropellant, nor do I create any liquid fuel or oxidizer.

This mission netted a profit of 2271 funds. And it did not break any rule (:

You may want to amend the rule to something like "You may not use any ore related parts"

Edited October 13, 2020 by camacju

[ManEatingApe]

14 hours ago, camacju said:

This mission netted a profit of 2271 funds. And it did not break any rule (:

You may want to amend the rule to something like "You may not use any ore related parts"

Clever use of the loophole. I have updated the rules based on your suggestion to close this exploit.
You now have the honour of a rule named after you and the infamy of an entry in the rogue's gallery.

Edited October 14, 2020 by ManEatingApe

[Pds314]

What is your feeling on counterintuitive abuse of the aerodynamics system?

[Pds314]

Alright. I've got a pretty good entry and it could be improved even more.

Cost: 3110.
Category: Lawn chair
Partcount: 9
DLC: Making History.
Launch mass, not including Kerbal: 9870 kg.

Summer shall begin her journey upside down in this rather unorthodox staging configuration.

The lander looks really impressive Delta-V wise. And it is, but somewhat less than it looks like. Here's what happens if we make sure Summer is actually in the ship. We have 4180 m/s of Delta-V, not 4602. That puts our total Delta-V at 6158, which is definitely enough to go the Mun without much optimization. I wonder if it could be modified for a Duna and return mission.

Because this rocket has way more thrust than necessary we go into an immediate hard turn and throttle down the SRB with action groups.

The SRB is spent, but we delay staging until the drag is lower, as upper stage is not aerodynamic when facing prograde and an extra 1.7 tonnes to help it push through the air can't hurt. Goodbye SRB.



We have a very large insertion burn. Out of 4180 m/s of Delta-V in this rather overpowered lander, we're gonna use more than a third of that, 1469 for circularization alone. In addition to our SRB, that puts our vacuum Delta-V for a 105 x 92 LKO at 3447. Not a remarkably efficient launch profile to be sure, but we can afford it.



Almost an entire orbit later, it's time to burn for the Mun. Goodbye Kerbin.

After circularizing on the Mun, we wait half an orbit to land on the sunlit side.

We didn't pick the best landing site, but it hardly matters because the lander definitely will tip over regardless.



We partake in the time honored tradition sacred to all Kerbalkind of the 500-meter Munar spin cycle.



And we eventually come to a stop. It would be nicer if we had been on a prograde-facing slope, but it doesn't matter. We've got 975 m/s of Delta-V and a Munar TWR of about 16. I'm quite sure we can get back to Kerbin.



Placing a flag.



Goodbye Mun. Hello Kerbin.



We set up our return trajectory.



We're back at Kerbin and end up with 60 m/s of delta-V remaining. We could maybe try to do lots of aerobraking and use that 60 m/s for something, but instead we're gonna use it to drop our Pe just a bit lower from 55 km down to 42 so we can burn off the fuel tanks and engine and get a nice big unaerodynamic face into the wind and slow down.



Coming in hot. Goodbye rocket.



We're gonna take a nearly flat trajectory at 42 km for awhile to slow down. We have no useful control at this point.



Beginning to descend after bleeding off our Munar reentry speed. Unfortunately we will be coming down in the darkness. Goodbye Kerbol.



No reason to save a chair and a service bay at the risk of potentially losing a Kerbal. We're ejecting.



Goodbye chair. Goodbye service bay.



Summer about to land.



Aaaand landed. Goodbye parachute.







Thoughts for an improved mission:
The part costs are as follows:
2 control surfaces: 800.
Thumper: 850, of which 492 is solid fuel
2 LF adapters/tanks: 320, of which 147 is LFO.
Spark: 240
1.25m Service bay: 500
Chair: 200
1.25m Decoupler: 200

So I think the most obvious form of extravagance here is the control surfaces. The question is what to replace them with. Reaction wheels would probably not be a significant improvement.

I think what I will do is add a couple basic fins, compensate for the drift having no rudder will cause by just doing a small plane change in my insertion burn, and have the first stage do a preset gravity turn because the fins are low enough to force the tank to lean over on the pad.

Edited October 20, 2020 by Pds314

[Pds314]

Alright. Time to beat the record I just set. Introducing the Munar Saucer 1.x

Cost: 2360
Category: Lawn chair
Partcount: 9
DLC: Making History.
Launch mass, not including Kerbal: 9790 kg.

This version does a pre-specified gravity turn, although it's not very exact because of wobble.


Editor screenshot. What do you mean two fins is less stable than three?



Sitting on the launchpad. Totally normal. Definitely not leaning so far it can barely stay upright.



This will be a quick launch. We are not throttling down this time.



We don't wanna stage until we hit near vacuum.



Stage!



Orbiting over the panhandle in our 115 by 105 orbit that took us 3391 m/s of vacuum delta-V to achieve. Eh. It's actually not that bad for a 110 SMA.



The plan. We need to do a slight plane change, which will happen mid-course.



Welcome to the dark side.



Our trajectory on the way to the Mun.



Kerbin is beautiful.



Our trajectory after alignment. Yeah it's bad. No I don't care. We have nearly 2 km/s of Delta-V. If we had just an ounce more I would add a Kerbal-only Minmus landing. We can afford to waste fuel.



Orbital insertion around the Mun.



Deorbitting.



The Saucer has landed. Almost perfectly on the terminator.



We notice the nearby hill is still light. Summer will go and investigate.



Summer chased the Terminator to the top of the hill. But at one point she tripped and cheated by using her Jetpack.



Back to the lander.



Cheaper Mun flag.



We cut it very close to a nearby crater rim. Just 46 meters from the ground at orbital speed. Summer seems mostly unphased by this.



We spot the flag of the previous mission up ahead.



And that of the current mission behind.



Our Kerbin reentry burns the tanks , but the engine actually survives and flies back onto an elliptical unstable orbit.



Safely descending in the general direction of the KSC, although we won't make it all the way there. We notice our landing pod survived to the ground somehow.



We can see the unstable debris will make some cool fireworks near the dessert airfield in around 8 hours.

I think with more optimized piloting and a slightly better craft design, sub-2000 might be possible.

Edited October 20, 2020 by Pds314

[ManEatingApe]

3 hours ago, Pds314 said:

Alright. I've got a pretty good entry and it could be improved even more.

Cost: 3110.
Category: Lawn chair
DLC: Making History.

...<snip>...

I think what I will do is add a couple basic fins, compensate for the drift having no rudder will cause by just doing a small plane change in my insertion burn, and have the first stage do a preset gravity turn because the fins are low enough to force the tank to lean over on the pad.

 

48 minutes ago, Pds314 said:

Alright. Time to beat the record I just set. Introducing the Munar Saucer 1.x

Cost: 2360
Category: Lawn chair
DLC: Making History.

...<snip>...

This version does a pre-specified gravity turn, although it's not very exact because of wobble.
I think with more optimized piloting and a slightly better craft design, sub-2000 might be possible.

You take 1st and 2nd spot on the command chair leaderboard and also are the first entry to use a DLC!

I like the upside down 2nd stage and precariosuly pre-tilted booster to induce a gravity turn.

[camacju]

https://imgur.com/a/5olo0cL

276.54 total funds. Three part spaceplane; I ditch the rapier, wings, intakes, and landing gear when they're no longer useful

[ManEatingApe]

2 hours ago, camacju said:

https://imgur.com/a/5olo0cL

276.54 total funds. Three part spaceplane; I ditch the rapier, wings, intakes, and landing gear when they're no longer useful

The recent forum updated deleted your previously detailed post and also my response <sigh>

The 3 part design optimising each segment of the mission is a great way to optimise cost!
The total cost of 276 funds is less than the KSC's daily snack budget.

Unfortunately I can't accept this entry - again it breaks the rule on excessive part clipping:

• The nuke clipped into the liquid fuel tank
• The Spark, 2 x donuts and Kerbal crammed into the service bay.

As a gameplay balance mechanic the nuke is long and awkward on purpose making it tricky to fit into spaceplane designs both large and small. I've lost many nukes to tailstrikes on takeoff and landing, gently irradiating the KSC.
 

Your design can work with a length stretch - unclip the nuke and liquid fuel tank and extract the dumpling from the service bay (and from each other).

[camacju]

Okay, will do

[Pds314]

Soon™

[Pds314]

Alright. The mission log is quite long and involves a lot of aerobraking and EVA pack abuse. I need a break. But I'll post it later.

Suffice to say 4740 cost is possible for a pod mission. And I even recovered the entire upper stage intact.

[Pds314]

Quick question/clarification for pod landings, does the pod need to survive or can you just jump out?

Edited October 21, 2020 by Pds314

[camacju]

https://imgur.com/a/CLhKjuV

263.5 funds

edit: Also why would the nuke clipping even change the risk of tailstrike? It's not even the farthest aft part in its stack

Edited October 21, 2020 by camacju