Rakaydos

First successful y connector docking. (album to come after the second docking) 5 more to go, plus repeated layer alignment redocks.

It's more an issue that the docking port I need to attach, and the docking port I'm using to push, do not line up. I'm looking at putting 2 ant-tugs on it, though, and eating the cosign losses for balanced thrust in line with the docking port.

...Y-connector pods are a pain in the ass to dock.

Ok, I believe I know a way to pull this assembly off. It's going to be messy and complicated, but it should be POSSIBLE. It's also going to take a minimum of 32 more launches (the above 20 launches still dont have enough DV, and I want a reserve available) so my updates may be slow.

Assuming the top layer is filledd with 2 Y-connector fuel pods, another pair above them, and the Y connectors have another set of pods all hanging off them... (Stage)2 tanks: 30.032 tons wet, 26.252 tons dry, 422.15 m/s (Stage)3 tanks: 36.8 tons wet, 31.13 tons dry, 525.9 m/s (stage)4 tanks: 45.824 tons wet, 38.264 tons dry, 564.8 (stage)4 tanks: 54.848 tons wet, 47.288 tons dry, 465.41 Still need another good KM/s for the direct approach. Adding another layer to the top... (Stage) 3 tanks: 61.616 tons wet, 55.946 tons dry, 331.34 m/s (stage) 4 tanks: 70.64 tons wet, 63.08 tons dry, 388.51 m/s ...this is gong to be a pain in the butt to multidock. The triple dock was bad enough, but now multiple 5x docks? Building out instead of up is another possibility, but floppyness awaits.

And the heat shield/kerbin return stage. https://imgur.com/a/4FLrXUR Just need to figure out how to get 26 tons from LKO to Tylo capture, now.

Meanwhile, Tylo orbital departure stage https://imgur.com/a/YzHAy9z

So, I have no idea what I'm doing with this math, but bear with me. A 2.5m heat shield has a cross section of about 5 square meters. (1.25^2 x 3.14 = 4.9) and the mass for the dry lifter + heat shield is about 2 tons and has a drag coefficent of 0.2. At a kerbin reentry velocity of 4500 m/s, that's about a 1g (9.8m/s/s) deceleration at 5/6 the atmospheic height, (58 km) if I read the math right. 10g deceleration at 4/6th the atmospheric height. (46 KM) Those height seem high, compared to other vehicals (which makes sence, since 2/3 of the mass is just ablator) so I suspect a single heat shield will be sufficent. But I may just be convincing myself here.

Except that, for the Tylo lander, I need a lander can instead of a capsule, which needs a 2.5m heatshield to protect it. Extra mass on return, but lighter on the TWR critical stages.

Currently working on a heat shield module and fuel for kerbin return. A lot depends on whether I need to bring 2 or just 1 heat shield, to reenter from jool intercept velocities, because each heat shield masses twice as much as the dry lander capsule. Any suggestions for computing this?

Tylo orbit circularization stage: https://imgur.com/a/LP3830E

If I've done my calculations correctly, this should be a functional Tylo lander and lifter.

Not much accomplished, but it may be amusing. https://imgur.com/a/HMSsyqA And the actual proper docking. https://imgur.com/a/2wOhg0F

Speaking of docking, documenting a rendevus and docking in screenshots is confusing. Especially when the first docking gets 90% completed when I discover I've been draining fuel from the payload and it's too late to quickload. Fortunately it was the pod, not the lifter.

Rendevus is much easier in caveman if there's a functional, powered probe core on the target. (it's the difference between needing a >150m blind flyby with ship swap, select port, ship swap, target port; and needing a >50m blind flyby and good rightclick skills to catch a docking port as it flies by.) The tylo lifter will need to rendezvous with something small to get it back to the mothership in high elliptical tylo orbit, 1210 m/s away. (plus a healthy rendezvous margin) Since this is a 1-off module, it can be more finely tuned than the pods, but it will have more dry mass. I pull out the Tylo lifter craft file, rename to Tylo escape tank, strip off all the stuff that stages away, drain the tanks, and (in the VAB) dock a probe core with 2 baguette tanks to it. 1.353 full, .995 dry, calculating out to 1360.51 m/s. A little tight on docking margin, I can waste up to 400 m/s just in kerbin orbit getting a rendevus and docking. Adding a third tank changes the wet to 1.838 and the dry to 1.029, for a DV of 1822.11 m/s, plenty of margin. (especially if I dock with reserve in the lander tanks, and lock those tanks as a docking reserve) Set the core to default to hybernation and lock the electric charge- I dont need it to actually control anything, just to let me target it easier. Reroot from the lander to the tanks, pull off the lander. Because I have the D/v margin, I throw on some solar panels too- there's none on the tylo lander or lifter, and the spark doesnt have an alternator. Adding .015 to both wet and dry mass drops the DV to 1802.18, which is still plenty. That gives a probe/tank mass (minus the lifter/capsule) of 1.066. 9.801 wet for the tylo lander/lifter, + 1.066 for the tylo orbit escape tank, is 10.867 tones I need to get from tylo escape to tylo orbit. again, 1210 m/s, but no need for a docking reserve. The lander already has 3 lightweight engines, so this is somethig that can be done by throwing standard fuel pods at the problem. (2.256 tons wet, .366 tons dry each) Two attached above the lander engine pods should be pretty secure- 15.369 wet, 11.599 dry is 883.17 m/s. A third pod as a separate stage above the orbit escape adds (17.625 wet 15.735 dry) 355.96, for a total of 1239.13 m/s, just clearing the maneuver. The stack is now 4 pods high, though, so wobbly rocket cosign losses may cost some of it. We'll see. Worst case, I recalculate the lander with 3 engine pods and the the tylo approach with 3+1 tanks, with the core using the y-connector pod varients. Docking all 4 port pairs at once may be difficult, but if it works it should be less wobbily. Thats probably as far as I should go without actual assembily and testing. Kerbin return requires at least 1700 m/s and 2.5m heat shields capable of bleeeding off something like 4400 m/s in kerbin atmosphere. (or at least 1200 of it on the 1st pass, for kerbin capture + a rescue mission)

THE FIRST COMPONENT IS IN ORBIT. (barring redesign) https://imgur.com/a/Ybrr4ni

Worst part is, I had a pretty well debugged lawn rocket, but I was overenthusiasic about deleting everything, and now need to rebuild it from scratch.

The fuel pods are 2.256 tons wet, .366 tons dry. A single Spark (2.548 tons of thrust on tylo) gives a positive TWR for a single tank. The lander is dead mass, so lets look at 3 tanks, docked parallel, no staging, with 2 additional sparks. (all lifter tanks locked down) 2.256+2.256+2.833(lander)+.2(two sparks)=7.545 wet, .366+.366+2.833(lander)+.2(two sparks)= 3.665 dry At 320 ISP (all sparks, leave the ants offline) thats... 2265.91 m/s. Not quite enough,but pretty close- in theory I could get away with using the lifter to go the rest of the way, but I'd have to ditch the landing shocks, which is a no-go. A 4th fuel pod, mounted on top on the tank's integrated decoupler as a separate stage... 7.545+2.256= 9.801 tons wet 7.545+.366= 7.911 tons dry =672.28 m/s (+2265.91 m/s = 2938.19 m/s) ...Should be good with a good approach.

Lightweight Caveman Tylo Lifter- Wet mass 2.833 tons https://imgur.com/a/JUSmsk9 Has a bit over 3200 m/s- a hefty reserve for rendevus and docking, and the possibility of having to manage the tylo landing approach on it's own, though the TWR is a bit low with the legs still on to be comfortable with that.

Whats the "Effective exaust velocity" of a Spark engine? Edit: Found a calculator that accepts ISP.

Yea, I threw everything out after that. This is what I've rebuilt so far: https://imgur.com/a/FEQf0xi I need to figure out what to DO with those wet/dry masses, but I have them. Currently writing up the lifter.

It's nothing that couldnt be done with lots of pencil and paper (Or more cheat menu orbit testing) but Jool mission grind is already bad enough. Since my tech tree is full already, this isnt even the challange proper anymore, "just" an Order of the Trilobite. If it's still a problem, I can uninstall it and go back to orbital tests.

Redesigned the Tylo lander again. The tylo lifter is still a single assembly that has to go up on a build-a-rocket, but the lander has been broken into 3 parts that should be assemble-able without cosign losses. Taking the Jool 5 Infinity video as inspiriation, I would also need an additional 1250 DV to go from a highly eliptical mothership parking orbit to low Tylo, with enough residuals to give the returning can 1250 DV back to the mothership and redevous. And Cavemen cant do bump-rendevus. That's managable. So I've started to look at what's needed to take the empty landercan to other jool moons and back. (using kerbal engineer for ship design) Turns out 2 of my "fuel pods" can get me Val and back with good flying. 1 pod each for Bop and Pol, with something like 300 m/s reserve for intercept, docking, and poor mission planning. Laythe will probably take an independant lander, and of course Kerbin requires at least 1 2.5m heat shield to protect the lander can from jool intercept velocity at kerbin, though I only need 1 more fuel pod if Ionly have 1 heat shield. A heatshield, probecore, battery, parachutes, 2 baguete tanks and solar panels gives a healthy margin and should have enough utility to return to kerbin. Masses: 2.25 tons for heat shield/parachute assembly, 2.176 tons per fuel pod (5 for Val, Bop, Pol and Kerbin), whatever the Layth lander ends up looking like, the Tylo lifter (2.753 tons), the 3 parts of the tylo lander(2.356 tons each), and the tylo orbit tanks (4 more fuel tanks). That's what a mothership needs to bring to Tylo eliptical orbit.

Redesigned a tylo lander stage that can carry the tylo lifter, but now I need a kerbin lifter that can manage 7.5 tons to kerbin orbit. Looks like I need some horizontal assembily.