sdj64

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About sdj64

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    Sr. Spacecraft Engineer
  1. So, I did see one error in my calculation: When I assumed the SSTO payload fraction of 35%, it didn't include any engines or wings used for Kerbin ascent (because the payload fraction challenge specified an inert payload). My test craft had a mass of about 45 tons full and 30 in orbit, for 66%, which puts chemical engines back in the realm of possibility for the Tylo landing and ascent. You can also use your efficient (ion or nuclear) engine in conjunction with your more powerful engines for Tylo, which could maybe save you some more. Good analysis, it's nice to see similar delta V figures. You might be able to save 200m/s by landing at speed and braking, and your first 200 m/s could use your most efficient engine to build up speed across the ground? I tried incorporating these changes into a craft, but I'm still coming up short. It has about 1000 m/s too low delta V on the "high thrust" part, and its TWR is only 0.5 where it needs to be 0.8 at Tylo landing. It also is missing electrical systems to run the ions and was tested with infinite electricity on. My spreadsheet says I can devote 5 tons to non-tank stuff, and I'm sitting around 6.5. How to increase the thrust and decrease the engine mass? I think it might be better to just use the rapiers on closed cycle - the engine mass savings might make up for the lower efficiency. If I use those, my non-tank budget drops to 4 tons, but I also lose 1 ton of Terriers, so it's an even trade and I get higher thrust for the Tylo landing.
  2. I played around a bit in the VAB with Kerbal Engineer, with little success. I could get maybe 3/4 of the way there on delta V. So then I turned to excel, because while it only takes one success to prove something possible, only math can prove something impossible. I'm not 100% sure on the assumptions I made, but I believe it is mathematically impossible to do a stock Tylo surface SSTO. The spreadsheet works from bottom to top, using the rocket equation to find the wet mass after each step of the mission and finally telling you what mass you have to devote to your fuel tanks and what you have left over for stuff like wings, cockpit, and engines. I assumed it takes 2000 m/s to go from Kerbin orbit to Tylo orbit, 4500 to land and ascend from Tylo, and 1000 to return home. With perfect gravity assists and piloting, you might be able to reduce those numbers. I also assumed the Kerbin ascent had a payload fraction of 35%, which was the highest I found in the recent payload fraction challenge. Edit: should have assumed much higher, because that fraction was an inert payload, not counting engines, wings, and systems. I got 66% in testing. Negative percentage for the "budget" line mean it's impossible to get the required delta V with that engine combination. https://drive.google.com/open?id=1ykMPBYGOo0YHkErJf0mClUfqGF-t1W5r
  3. The Mobile Base Challenge

    A short hop could mean 5 minutes (or some time) of flight time at 1.0 TWR or higher (or lower, if using wings?) for that world. Amphibious could mean it can travel 20km (or some distance) across water before needing to refuel. I agree that the tank capacity for fuels is sort of arbitrary? For example, I usually don't transport ore in a mining operation - all of my mining ships also have a converter, so I only put the smallest ore tank on. Also on Laythe, Eve, or Tylo, there's no chance that an ion craft will need to be refueled at the base - it can't get there in the first place. I'm sure everyone will disagree on what multipliers are best, but what number is being multiplied? Do you start with a score of 1 for meeting the requirements?
  4. The Mun 4 Challenge

    Cool challenge, I totally approve of a less-challenging "proving ground" for the Jool 5! I do like the scoring system, it seems to reward more interesting solutions and give it more excitement for the veterans as well. Take a single stage Mun lander. Add a parachute. You now have a Duna lander! okay you have to add about 200 delta V but that's not so hard to do
  5. Origami Steel Fleet

    I built one a while ago but then forgot about it when I changed the carrier design so a plane could ride outside. This plane was made for gathering science from Laythe, and needs to be carried in a Mk3 spaceplane that can land horizontally. The wheels are not powered, but it's not really a big deal - there are two Vernors in the front that push it backwards out of the cargo bay, and the engine can do the rest. It does have a big flaw, which is that it has no real cockpit so it needs a comnet connection to fly.
  6. Yes, science from Jool including its high and low orbit, and atmosphere, counts. Moon orbit space science also counts. Science earned from a lab does not count, and anyway you would have to land the lab because transmitting science does not count. Since turning ComNet off entirely is allowed, you can use your relays. You can also use any ore scans you have already performed, or send a scanning satellite separately ahead of the mission.
  7. Does orbital speed have to be Kerbin orbit? If so, can you leave Kerbin orbit and come back (getting a high speed in solar orbit and then diving back towards Kerbin)? Can you use gravity assists? Also, does it have to be manned and if so, are seats allowed? I do like the "king of the hill" style of scoring, where you have to beat all 3 of the previous best entry. It could get to the point where just one of the records is really impressive, and the other two could still be easily beaten. For example, I can think of a couple ways to game the space record, especially if the answer to some of the above questions is "yes"...
  8. Yes, that would be cool to see. As long as your rescale includes all of Jool's moons orbiting Jool in the same order and at least 1x their stock size (some rescales change Bop and Pol differently, for instance - just make sure they are not smaller than stock), it is allowed.
  9. Right here. It's the all-time low mass record holder, too. It was done in version 1.1 by @Nefrums
  10. Command seats are allowed, but every Kerbal on the mission must sit in a pod or cabin while in the Sun's SOI. A Tylo lander with just seats is fine. (rule 5) FYI, the smallest number of engines used in a Jool 5 mission so far (without ISRU) is 3: a Rapier, a Spark, and a Dawn. With ISRU, it has been done with just 1 mammoth!
  11. @Cpt Kerbalkrunch Congratulations, you have completed the Jool 5 Challenge on Jeb's Level! The mission actually seems fairly efficient, given the constraints of the heavy pod and lack of nuclear propulsion. The swappable pod was an effective strategy for this mission profile, and I don't think anyone has done 5 kerbals and 3 per landing before. Your 1510 Science points puts you in second place! ...Jeb's level is not very popular these days. I look forward to your proposed Eve mission. Given that you're using the same Mk1-2 pod for every landing, I might recommend you try The Ultimate Challenge - with Jool and Eve done, you'll have all the hard landings out of the way!
  12. Interplanetary Marksman Challenge!

    Got a decent cannon using a Rhino, because it's the highest thrust single engine bell. It uses a Rockomax decoupler clipped into it, rather than a separator, so that there's no debris between the engine and the cubic strut. The strut overheats immediately so I have "ignore max temperature" turned on... Easily hits the Mun at 43858 m/s Shot at Eve, but couldn't aim more accurately than this. Perhaps a crew cockpit or a detailed readout of the angle versus the maneuver node could have helped. It passes Eve periapsis within 6 days of launch.
  13. Submitting two designs: the Cobalt Air Bluejay 32 for the small regional jet category, and the Goosewing 80 for the medium regional jet category. The Bluejay 32 is a stylish and fast small plane that holds 32 passengers. Its speed, range, and cruising altitude set it apart from planes of its size, making it perfect for routes that would be unreachable with other small jets, and uneconomical with larger ones. For improved performance and fuel economy on shorter routes, it can be flown with less than a full fuel load. Cost: 17,991,000 Cruising altitude: 8500m Cruising speed: 275m/s Range: 1900km Takeoff Velocity: 55m/s KerbalX link: https://kerbalx.com/sdj64/Cobalt-Air-BlueJay-32 The Goosewing 80 is a medium jet that holds 80 passengers, exceeding the minimum requirement of 72. Its shape is inspired by a concept aircraft designed by MIT, with features emphasizing fuel efficiency. Like its inspiration, the Goosewing gets impressive fuel economy, with fuel cost per passenger just 55% of the Bluejay's. This efficiency does come at the price of speed, in fact, if the cruising speed is reduced further to around 220 m/s the plane is just capable of reaching the extended range target. Cost: 32,341,000 Cruising altitude: 8000m Cruising speed: 245m/s Range: 1800km Takeoff Velocity: 60m/s KerbalX link: https://kerbalx.com/sdj64/Cobalt-Air-Goosewing-80
  14. Mine wasn't the first, but it might be the one you're thinking of. It entered into several missions of the Shuttle Challenge but I decided to do something different for the most recent. It should still work in the current version of KSP. https://kerbalx.com/sdj64/Chevalier-Shuttle-H2
  15. @IncongruousGoat Congratulations, you have completed the Jool 5 Challenge on Level 2! The modular crew and science pod seemed to work well, and I liked the 3 way symmetry and cage-like construction of your mothership that allowed you to keep your center of mass in line when removing each lander. Yet another well-executed Jool 5, you now have one for each of the levels 1, 2, and 3!