# KSP Caveman Challenge 1.2

## 173 posts in this topic

Posted (edited)

14 hours ago, galactictaco said:

it should be, at least orbiting the sun. people got proper flybys of duna and eve? with returns? impressive. id have to break the rules and reinstall KE to play with it before i had any confidence sending that mission.

edit: i suppose it would be easy if you didnt care about time...i cant stand waiting for minutes of time warp as my kerbal flies around the sun 8 or 9 times waiting for kerbin to be in the right position

@galactictaco There's some tricks you can use so that you don't have to rely on luck or extreme time warp to get an intercept.

The algorithm I've used in the past is:

• Raise AP to target e.g Duna
• Once at AP, if you're ahead of Duna then raise your PE to just above Duna's (conversely if you're behind Duna then raise your PE to just below)
• Timewarp - you'll either catch up slowly (or Duna will overtake you)
• As you get closer to the planet adjust your orbit to match more closely (you don't want to overshoot/undershoot)

To optimise things you can calculate the phase angle (the angle between Kerbin and your destination) from first principles and crude cave paintings (but it's not strictly necessary):

Spoiler

Start with Kepler's 3rd law: "The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit"

A Hohmann transfer orbit from Kerbin will have a semi-major axis of the average of Kerbin's orbit and your destination (if both orbits are roughly circular)

k is Kerbin's orbital radius and d is Duna's.

We want to calculate the phase angle - this is the angle of our destination relative to Kerbin, so that when we reach the AP of our Hohmann transfer, our destination planet is there at the same time. Our transfer will take 180° (half an orbit). So the phase angle is 180° minus the fraction of the orbit the destination will make in the time it takes for our transfer orbit.

49° is close enough to 45°, so you can estimate by eyeball when zoomed out in the Tracking Station, e.g your view should look like:

The 2 planets I'd suggest are:

Duna -

• Close to Kerbin (only about 100m/s dV needed over Kerbin escape velocity)
• Practically 0° inclination to Kerbin
• Almost circular orbit (low eccentricity) so doesn't matter too much when you set out
• Atmosphere for Aerobraking
• It's feasible to land and get back with Caveman tech.

Jool -

• Massive SOI - so easier to clip it with the primitive rendezvous algorithm above
• Atmosphere for Aerobraking
• Almost circular orbit
• I can't recall any manned Caveman mission there before, so you could claim some serious props
• It's a lot of fun ping-ponging between all the Joolian moons with gravity assists (intentional or not )

Edited by ManEatingApe
Simplify diagram
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2 hours ago, ManEatingApe said:

Duna -

• Close to Kerbin (only about 100m/s dV needed over Kerbin escape velocity)
• Practically 0° inclination to Kerbin
• Almost circular orbit (low eccentricity) so doesn't matter too much when you set out
• Atmosphere for Aerobraking
• It's feasible to land and get back with Caveman tech.

this must involve some lawn building cause i cant comprehend having the delta v in orbit without fuel cross feed that even remotely gets a landing and return manned from dun but not the mun. even with aero breaking

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Posted (edited)

6 minutes ago, galactictaco said:

this must involve some lawn building cause i cant comprehend having the delta v in orbit without fuel cross feed that even remotely gets a landing and return manned from dun but not the mun. even with aero breaking

Yep exactly, you'll need more than 1 launch to get a manned mission to Duna. There's a few approaches:

• Lawn building (just like you said)
• Rendezvous and assemble in LKO.
• Land everything on Minimus and assemble it there
• All of the above!
Edited by ManEatingApe

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Posted (edited)

Ok, this is the first part of my attempt!

Edited by Alpheratz
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On 3/13/2017 at 4:52 AM, ManEatingApe said:

Yep exactly, you'll need more than 1 launch to get a manned mission to Duna. There's a few approaches:

• Lawn building (just like you said)
• Rendezvous and assemble in LKO.
• Land everything on Minimus and assemble it there
• All of the above!

Having recently done some LKO assembly, I'd suggest going with lawn building.. regardless of the hassles involved, it's got to be better than orbital assembly.

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On 3/12/2017 at 9:52 PM, Alpheratz said:

Ok, this is the first part of my attempt!

following suit, http://imgur.com/ZpHuww1

i propose a mission challenge of using this to ferry a single verbal to and from the surface of the mun. i also propose someone other than me does it.

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15 hours ago, galactictaco said:

following suit, http://imgur.com/ZpHuww1

i propose a mission challenge of using this to ferry a single verbal to and from the surface of the mun. i also propose someone other than me does it.

Challenge accepted

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On 3/14/2017 at 2:38 PM, Alpheratz said:

Challenge accepted

im sending a rescue mission eventually, gotta get jeb home safe.

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1 hour ago, galactictaco said:

im sending a rescue mission eventually, gotta get jeb home safe.

Heh.. That's quite a challenge you've set yourself.. good luck!

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Ah! Wound up about a couple hundred m/s short on the Mun-and-return mission! This is definitely non-trivial with the mk1 and the experiment storage unit. Maybe the landing can and no experiment returns would fare better? After all, by the point-and-time you have the landing can, though, there's not much caveman challenge science left to go.

The Terrier 'circularization' stage was a little anemic for where the Reliant left off, but besides that everything in the flight went great- even the combined Mun capture+suicide burn. The end goal wasn't a success, but it was definitely fun to fly and good for the learning.

Good luck to @Alpheratz and @galactictaco on this!

Spoiler

Images are compressed and should be expandable...

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16 hours ago, Cunjo Carl said:

Maybe the landing can and no experiment returns would fare better? After all, by the point-and-time you have the landing can, though, there's not much caveman challenge science left to go.

The Lander Can is significantly lighter than the Mk1 Capsule. So that's a DV advantage right there. And you only really need the Science Container if you can't physically return the experiments to Kerbin's surface.

1 hour ago, galactictaco said:

Well done!

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7 minutes ago, JAFO said:

The Lander Can is significantly lighter than the Mk1 Capsule. So that's a DV advantage right there. And you only really need the Science Container if you can't physically return the experiments to Kerbin's surface.

Well done!

it felt very 'mercury style' to send and land a kerbal just holding a ladder. i dealt with time warp by letting him drift around (furthest he got was 1.6 KM on the way in, but i was much more lucky on the return and he kept along side for good chunks of flight) which added to the sense of smallness and insecurity. all he had was his little EVA pack as a life line if he drifted too far. it'd never be enough to get him home if his vessel failed and it would probably be too little too late as an emergency escape system if he slid off the edge of his ladder. very eery.

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Just now, JAFO said:

The Lander Can is significantly lighter than the Mk1 Capsule. So that's a DV advantage right there. And you only really need the Science Container if you can't physically return the experiments to Kerbin's surface.

Totally! Only downside of the landing can is it requires a lot of science to obtain. I was aiming for a "how low can you go" in science and missed the mark by a hair! A 200m/s hair, but hey who's counting .  The science container is also useful for collecting/resetting things like the thermometer, so a single thermometer can be used for a dozen experiments, which really maximizes the value of a trip. I've seen a way for pods to collect data from action groups, but without upgraded VAB or Kerbal EVA, I thought they couldn't collect science. Maybe I just missed it?

@Alpheratz Sending a Kerbal to space hanging on to the outside of a capsule? Ingenuous. I love it!

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5 minutes ago, galactictaco said:

it felt very 'mercury style' to send and land a kerbal just holding a ladder. i dealt with time warp by letting him drift around (furthest he got was 1.6 KM on the way in, but i was much more lucky on the return and he kept along side for good chunks of flight) which added to the sense of smallness and insecurity. all he had was his little EVA pack as a life line if he drifted too far. it'd never be enough to get him home if his vessel failed and it would probably be too little too late as an emergency escape system if he slid off the edge of his ladder. very eery.

That had to have been quite a nerve-wracking voyage.. I salute you, sir!

4 minutes ago, Cunjo Carl said:

Totally! Only downside of the landing can is it requires a lot of science to obtain. I was aiming for a "how low can you go" in science and missed the mark by a hair! A 200m/s hair, but hey who's counting .  The science container is also useful for collecting/resetting things like the thermometer, so a single thermometer can be used for a dozen experiments, which really maximizes the value of a trip. I've seen a way for pods to collect data from action groups, but without upgraded VAB or Kerbal EVA, I thought they couldn't collect science. Maybe I just missed it?

In this case 200m/s definitely counts as a hair. I'm quite impressed by that craft, and fully intend stealing the design!

I'd forgotten about the thermometer reset trick.. good call.

And no, you didn't miss anything. Caveman pods can't collect data, or do action groups.

I must say, I'm constantly impressed by the ingenuity and courage shown by the latest crop of Cavemen.. even after the Challenge has been running all this time, you continue to come up with new, innovative solutions. Congratulations all of you!

In other news, I've been looking into the feasibility or otherwise of "stacking" antennas for Eve/Duna probes. In theory, it's possible to combine enough HG-5 antennas on a probe to contact Kerbin from other planets, so I set myself the task of determining if the quantity necessary was practical to achieve.. obviously it would need a number of comms modules docked together in orbit, the question was, how many modules would be needed?

In a sandbox game, I placed 8 HG-5s around an OKTO core, then duplicated and stacked the setup as many times as I thought would be necessary. It turned out that with a Level 3 Tracking Station, and Eve at close approach to Kerbin, it took 88 HG-5s to get an 11% signal. I estimate that at very closest approach, that might go up as high as 15%. Some rough calcu-guess-timations suggest that with a Level 1 Tracking Station, something on the order of 500-1000 HG-5s would be needed to establish the same connection. And even then, Eve would be out of range for around 90% of its orbit!

As for Duna.. well, let's just forget about that.

So, for Cavemen considering Eve/Duna/beyond missions, there really is no option but crewed missions.

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My caveman spaceplane program was a fair success, succeeding in chucking one lucky volunteer on an interstellar trajectory! Guess how many m/s short it was of a full Mun mission .

Spoiler

200m/s, it seems. Uncanny, that. Still, worth it!

I'll be heading off to checkout the prerelease from here, but I'll be sure to mention if there's any new tidbits for us cavemen to strike with stones. Best of luck on the Mun missions, I'm rooting for you!

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Posted (edited)

@galactictaco I was inspired by your Kerbal ladder shenanigans to see how much science could be squeezed out of the very first launch.

Poor Bob clutched the ladder all the way to orbit with nothing but a Goo container between him and an untimely demise!

100 science was successfully collected on Normal difficulty (and that's even forgetting to run a report or two), not too shabby for a debut mission.

Edited by ManEatingApe
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On 17/03/2017 at 8:51 PM, Cunjo Carl said:

Totally! Only downside of the landing can is it requires a lot of science to obtain. I was aiming for a "how low can you go" in science and missed the mark by a hair! A 200m/s hair, but hey who's counting .  The science container is also useful for collecting/resetting things like the thermometer, so a single thermometer can be used for a dozen experiments, which really maximizes the value of a trip. I've seen a way for pods to collect data from action groups, but without upgraded VAB or Kerbal EVA, I thought they couldn't collect science. Maybe I just missed it?

@Alpheratz Sending a Kerbal to space hanging on to the outside of a capsule? Ingenuous. I love it!

Yeah, and it turns out you don't even need a symmetric design. By offsetting the capsule and taking into account the mass of the kerbal you can get a stable flight without too much trouble

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9 hours ago, Alpheratz said:

Yeah, and it turns out you don't even need a symmetric design. By offsetting the capsule and taking into account the mass of the kerbal you can get a stable flight without too much trouble

I like it! Kerbin low-orbit EVA science made easy. If those darn struts weren't such a drag, it could add some real deltaV to our upper limit from those ~500m/s jet packs.

Oh! Turns out v1.2.9 holds no surprises for us cavefolk. Physics (including aero) is unchanged, and I haven't seen any changes or additions to parts yet.

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On 3/21/2017 at 9:57 PM, Cunjo Carl said:

I like it! Kerbin low-orbit EVA science made easy. If those darn struts weren't such a drag, it could add some real deltaV to our upper limit from those ~500m/s jet packs.

the trick is to leave him in orbit and send up a little probodyne with a ladder on top.

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some rover designs in my non kerbin science fueled caveman run.

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Posted (edited)

@galactictaco That seems like a very sensible way to run a Mun mission . Unfortunately, I literally need to be prodded into rendezvous-ing anything, and doing it without maneuver nodes sounds crazy hard! By the way, the KSP mission system keeps trying to get me to rendezvous in the orbit of the Mun with caveman levels of upgrades... is that.... doable? It sounds like an enormous undertaking to me!

Edited by Cunjo Carl

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Posted (edited)

18 minutes ago, Cunjo Carl said:

@galactictaco That seems like a very sensible way to run a Mun mission . Unfortunately, I literally need to be prodded into rendezvous-ing anything, and doing it without maneuver nodes sounds crazy hard! By the way, the KSP mission system keeps trying to get me to rendezvous in the orbit of the Mun with caveman levels of upgrades... is that.... doable? It sounds like an enormous undertaking to me!

for LKO rendezvous you launch when your kerbal is about over the second patch of desert on the other continent, maybe over the ocean right next to our continent. normal launch but go a little higher than the kerbal, you're probably gonna be early. a few tries and you'll get it. all you need is to get close, then if you're behind it, try to orbit a little under, and if you're in front of it go a little higher. it will slowly come closer, don't worry about rendezvous. then when its within a few Km or closer (closer the better) switch to the kerbal and EVA pack your way over.

an apollo moon landing with caveman should in principle be doable but you would need cross feed to make it enjoyable. but with enough math and enough low orbit construction, sure...start with your return vehicle, get it in orbit with enough fuel, then build backwards, docking a lander module, then adding your insertion/return vehicle(s) and then build up a rear stage to transfer that all into an intercept trajectory. if you throw a handle on it you could bring a kerbal along, but you need enough return delta V to avoid aerobraking, so thats scaling up your insertion/return stage and this means an even BIGGER transfer stage. altho the kerbals 500 (probably less by a good amount i the end since he floats off in time warp and needs it to keep with his vessel, both going there AND coming back) could be used for part of your braking if he carries the science, and you just make an OP verbal launcher to go get him, but you will need a better rendezvous method since he will be out of fuel, so save a bit

id say start doing apollo missions in sandbox to get in the swing of orbital docking on the mun (on kerbin its easy once you learn when to launch). its a fun way to do it, especially if you set the orbiter nice and low, you wind up waiting till its coming up fast and you punch the accelerator and fly a Km over the surface racing up to speed. haven't done it without patched conics tho, but it'd be fairly straight forward. like a brute force docking. just keep your orbiter like 6Km above the surface when it comes past you, then just keep your target icon on your retrograde (i think?) and pray you have enough fuel.

Edited by galactictaco
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Posted (edited)

4 hours ago, galactictaco said:

some rover designs in my non kerbin science fueled caveman run.

Nice! I liked the extended comments, too.

Also, it appears Imgur albums now work properly in the forum again! Excellent.

3 hours ago, Cunjo Carl said:

By the way, the KSP mission system keeps trying to get me to rendezvous in the orbit of the Mun with caveman levels of upgrades... is that.... doable? It sounds like an enormous undertaking to me!

galactictaco gives a lot of good, sensible advice above.. but as he notes, that will only get you so far, when rendezvousing at the Mun.

So I'd like to point out that none of the orbital rendezvous' involved in the assembly of my Mun-return lander mission detailed above, were done 'sensibly'. I launched whenever I was ready to go, even if my target was on the other side of Kerbin, and took care of all the phasing orbits by eye. A couple of times I didn't even bother with matching planes first (a fancy way of saying; I forgot!), I just kind of took care of it all on-the-fly.

One tip that I picked up in a Scott Manley video, that came in handy, was this.. So you've got your catchup/slowdown orbit going nicely, how do you know when you're at the right point to raise/lower your orbit to that of your target, to get an intercept? For LKO, the magic number is 7. For instance, if you're at a 90km orbit, and your target is at an 80km orbit, the difference in altitude is 10km. 10x7 = 70, so when the target distance is about 70km (behind you, in this case, since the target is catching up), you should burn to put your Pe down to 80km on the far side of Kerbin. It's rough, so it's not guaranteed to get you a close intercept, but you will get close enough that you can work with it.

This value is not guaranteed to work at much higher orbits, or other planets/bodies, but it's a starting point, at least. Some experimentation should turn up a similar value for the Mun.

Finally, although GT was talking in terms of an Apollo style rendezvous, I doubt that's what the contract you mentioned called for.. I imagine it would be happy with any 2 vessels rendezvousing at the Mun, regardless of other mission details. So you don't necessarily have to land and return from the surface.. any 2 (separately launched, very important!) probes achieving a Munar rendezvous would fulfill the contract requirements. That's a whole lot simpler to achieve than an Apollo style Mun rendezvous.

Edit to add: also, "rendezvous" in a contract does not mean the same thing as "dock". Once your two craft are close enough to each other at low relative velocities (and the game is quite generous about what is "close enough"), the contract will be deemed fulfilled.

Give it a shot.. sure, it won't be easy, but for Cavemen, very little is. If/when you pull it off, it will lift your KSP gameplay skills to new heights.

Edited by JAFO
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Hi all

Here is my submission in hard mode, without any experiment from Kerbin's land, water or athmosphere to make it a bit harder.

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