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About Grogs

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  1. Awww I mean, yay! Thanks for the cool challenge. It was a lot of fun and it gave me a reason to visit some places I've never been to like Eeloo, the Mohole, the Dead Space Kraken, and Vallhenge.
  2. Well, in fairness you did ask for the most efficient engine. The price for bleeding-edge efficiency is, yeah, low TWR. I did a mockup of something similar to what you have with a probe core and 4 S3-14400 tanks plus and ADPT 2-3 adapter on top. (EDIT: Now that I'm looking at your total mass, maybe those are S3-7200s you have? Still, same principle should apply). So with a single Wolfhound, you get 7900 m/s. That's pretty extreme for a single stage, but your vacuum TWR is only 0.11. You could use an engine plate and stack 3 Wolfhounds. It would almost triple your TWR - so burn time down to 6 minutes or so. The trade off is your dV is down to 7384 m/s. Or use a Rhino. Still pretty efficient at 340 ISP and gives 2000 kN vs. the Wolfhound's 375. dV is down to 6700, but the TWR is 0.58. That should get you down to about a 3.5 minute burn, which is pretty manageable IMO. BTW, I've read that a good rule of thumb is that a burn should be less than 1/6 of an orbit to avoid big cosine losses. In your screenshot you're in about a 52 minute orbit so anything less than about 8 minutes should be OK.
  3. @Superfluous J, I'm happy to report that Joolollo is now complete. You can find the details over at my mission report here: I finished it up today before 1.10 came out so I could check it out. No worries if it takes you a while to review it. I've got a comet to visit! Maybe I'll pull Bob, Jeb, and Val out of retirement for a manned mission there after I send a probe.
  4. I've found that flashing markers usually indicate it's on a later orbit. So you've probably plotted a course that will take you between Kerbin and Duna orbit, but won't actually get you near the planet until the 2nd (or more) pass of Duna's orbit. Hope you packed a lot of snacks!
  5. Chapter 11: Victory over Vall; Homecoming FROM: KSC Mission Control TO: Bob Kerman, KSS Victory Prime DTG: 27:279:03:00 -------------------------MESSAGE FOLLOWS Understand you've reunited at Jool Station and are now preparing for mission to Vall. KAS has detected another anamoly on the surface of Vall at 60° 5′ 10″ S 83° 46′ 48″ E. Please investigate if possible. Good luck on your final moon. -------------------------END MESSAGE
  6. I did a quick test and I'm going to have to admit that I'm wrong on this one, at least in a specific case like Moho. I chose a scenario where we're inbound to Moho with a target orbit of 1 million meters (1 Mm). I launched from Kerbin, then had to make a correction burn to get a Moho intercept. I chose 2 different Pe's: 15 km and 1 Mm. In both cases, the capture was set for an Ap of 9 Mm, which is close to the Moho SOI. For the 15 km case, I then added a burn at Ap to raise the Pe up to 1 Mm. At that point, both orbits are equal and any subsequent maneuvering would be, too. Case 1: Inital Pe @ 15 km: Capture burn is 3004.3 m/s. The burn to raise Pe to 1 Mm is 34.0 m/s. Total dV = 3038.3 m/s. Case 2: Initial Pe is 1 Mm. Capture burn (and total) is 3504.2 m/s. This is about 466 m/s more than case 1. Some caveats: - This is a pretty extreme case dealing with such a fast approach speed and a very high target orbit. I suspect it does get into the gate orbit concept @OHara mentioned and that there's a cutoff Pe where it's more efficient to burn at the target Pe instead of as low as possible. I recall a really old thread where someone had calculated these orbits for each pair of bodies, but I can't find it now. - In practical terms, you also have to consider that the maneuver calculator assumes an instantaneous burn. Coming in hot to Moho a lot of the burn will be far from Pe unless you have a very high TWR. Still, we're talking a savings of 13% of dV so even a fairly long burn should realize significant savings.
  7. I think the cost of having to raise your Pe back up again is going to outweigh any savings from Oberth. I would choose a) for the first choice. For the second situation I would choose a variation of c) for the same reason. Ideally, come in on the same plane as the station and set your Pe on its orbit. Then when you do your capture burn you could set your Ap so that you intercept the station the next time you swing back down to Pe. You don't really have to calculate to pull it off, just set the station as the target and burn until the two position markers come together. There's no reason you have to do it that way, but it feels like the most elegant solution.
  8. Chapter 10: Bob's Tale - Red Shirts; What the heck is that thing? FROM: Bob Kerman, KSS Victory Prime TO: KSC Mission Control DTG: 27:279:02:23 -------------------------MESSAGE FOLLOWS Pol and Bop missions complete. Linked up with KSS Titan and Leviathan and consolidated crew. Preparing for mission to Vall. -------------------------END MESSAGE
  9. If you have Making History, the Wolfhound is a good long-haul vacuum engine for a fairly large craft. At 380 vacuum ISP, it's the best chemical engine I believe. I find it to be good for a transfer stage to move a relatively large payload a long way. I used 7 of them in an asparagus setup to move a 300-ton payload from low-Kerbin orbit to Jool. The stage gives about 4500 m/s dV. For something mid-sized, the Poodle is a good engine. The ISP is a little lower, but it's half the mass which makes up for it. This was my Moho return craft and it had about 3500 m/s. That's not enough to make Kerbin orbit, but plenty to get back and make a direct re-entry. If you need more dV, you can go with a Nerv setup. I think this one had about 5,000 fully fueled.
  10. Chapter 9: Val's Tale, or Ladies' Night on Laythe. Also, Natalo gets a little hot under the collar. FROM: Valentina Kerman, KSS Leviathan TO: KSC Mission Control DTG: 27:223:03:35 -------------------------MESSAGE FOLLOWS Laythe mission complete. Linked up with KSS Titan IVO Jool Station. Awaiting return of KSS Victory from Bop. -------------------------END MESSAGE
  11. Chapter 8: Jeb's Tale, or Tackling Tylo FROM: Jeb Kerman, KSS Titan TO: KSC Mission Control DTG: 27:214:04:00 -------------------------MESSAGE FOLLOWS Tylo mission complete. KSS Titan now in orbit with Jool Station. Awaiting return of the other ships. -------------------------END MESSAGE
  12. CHAPTER 7: Off to the Moons, or Breaking up is hard to do FROM: KSC Mission Control TO: Bob Kerman, KSS Joolollo Victory DTG: 27:145:1:30 -------------------------MESSAGE FOLLOWS Victory crew, we're happy to hear that you arrived safely at Jool Station orbit. There are a bunch of smiling faces down here in mission control. We're sending you a small maneuver to match your inclination to the inner moons. After this burn is complete, you have the go-ahead to proceed with separation ops. We received your recommendation to move the telescope off the Leviathan over to the Victory. We agree now that you've already flown by Laythe there's no need for Leviathan to carry it. Wernher did some calculations and mounting it on the ventral docking port of the Victory should have a negligible impact on your center of gravity. That will let you get observations around Vall, Pol, and Bop. Recommend you use the Vall lander to reposition it. We're also including burns for the Victory, Titan, and Leviathan to transfer to their respective moons. Modify as necessary to meet mission objectives. BTW, Rich set up a special two-burn maneuver for the Leviathan to get a close-up look at Jool's upper atmosphere. We hope you like green because you'll be seeing a lot of it. -------------------------END MESSAGE
  13. Great job. Doing a kerbed return mission to Eve is probably the hardest thing in the game. Other than maybe landing on Tylo, everything else should be easier. I've discovered a lot of the things you reported, like when to drop upper and lower heatshields myself through trial and error. I generally use the same methods. I like that you were able to put a nose cone on top and still attach an upper heat shield. I always get stuck with an uncovered docking port on top of my ascent stage, which then adds drag on the way out. BTW, I find it funny how wordy some of the Spanish translations on the science reports are. I can't imagine building an Eve lander without doing some testing with ALT-F12 cheats. Maybe some of the guys who have done it a dozen times don't need it, but I couldn't deal with getting all the way there and finding my mission failed because I mounted one decoupler wrong. Eve is unforgiving of even the slightest mistakes, and sometimes even when I do things perfectly something will randomly explode.
  14. Hey, glad to hear it. It's not just KER either. Sometimes I get two different answers from Mechjeb and the VAB and they're both wrong.
  15. Chapter 6: Traveling to Jool, or a game of cosmic pinball KSC: Victory, we heard about that zero-gee limbo contest you guys had last night. Hard to believe Jeb managed to win a limbo contest with his gut. Jeb: Hey, these are rock-hard abs here! KSC: Sure, we believe you Jeb. We're transmitting you a mid-course correction for your Jool intercept.