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camacju

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  1. You may be using too much wing area then. 5 degrees is close to the optimal value for SSTO craft (I think 4 degrees is slightly better but it's pretty close). Maybe you're used to low wing incidence requiring more actual wing area so when you rotate your wings upward you get a lot of drag. I like to aim for at least 6 tons per wing area, which leads to quite small wings for the plane's size but the increased lift from the wings makes up for that.
  2. I probably put way too much thought into this flight. In KSP, engines have a specific impulse - they consume fuel for a given thrust. Since work=force*distance, power=thrust*speed, so for a given thrust we want to be flying as quickly as possible. This means minimizing drag. And since the Juno has low thrust, this also means not including as much fuel as I can physically take off with. If I do that, I get stuck around the sound barrier and have to eat a very big lift to drag penalty. Interestingly enough, the Juno tops out at around Mach 2.05, which also is near a peak in lift to drag ratio. So this is my desired flight regime. Craft in SPH. One Juno, one control surface, and as much fuel as I can pack while still being able to go through the sound barrier. At this point, I point near the horizon and don't try to manage altitude or thrust at all. Full throttle is better because I can fly faster and at a point farther to the right on the Juno's thrust curve, which increases specific power output of the engine. I just keep a -1 degree angle of attack for maximum L/D and let the aerodynamics balance themselves out - it'll naturally balance at the correct point where the Juno's thrust is just enough to overcome drag, which is also the maximum speed it can attain for a given mass. Final result - 7 laps around Kerbin, single kerbal craft
  3. I got eight laps around Kerbin but I misread the rule that required only one Juno engine. A few hours wasted - back to the drawing board...
  4. I was more talking about mass per effective wing area - a heat shield's wing area isn't very large. Also if I remember correctly a 0.625m heat shield doesn't have an internal attachment node, which means it can't really be used as a magic wing. 0.625m heat shield with all ablator drained is 125 funds and 25 kg. The small hardpoint is 60 funds and the structural pylon is 125 funds, both of which have the advantage of being radial attachable. The 0.625m decoupler and separator are 10 kg, the small docking port is 20 kg, and the TT-38K radial decoupler is 25 kg. Lift to drag ratio is also very important for range. If you have a higher L/D, you can achieve the same lift for less drag. This means if you are flying at the same speed and altitude, you need less thrust to maintain level flight. This would mean less prop torque = less electricity usage. KSP wings are symmetric - zero AoA means zero lift. If you go into AeroGUI it should tell you your actual AoA. If 2 degrees wing incidence is making you struggle and fly slower, that means your wing area is too high - it'll produce more lift but also more drag - so you should reduce your wing. It'll help reduce mass also. Not at all - the idea is that they provide a superior lift to drag ratio in all flight regimes. It's just that they take less of a penalty from Mach effects, so their relative advantage over standard wings is magnified when at supersonic speeds.
  5. There's still plenty of funky aerodynamics stuff to work with. For example there's a few different types of parts that can be used as "Magic wings," basically parts that can produce a higher lift to drag ratio than any of KSP's normal wings: -Heat shields. These are the "standard" magic wing parts, but they're quite heavy and our ultra-low-power props will probably have a hard time getting them up to speed. -Landing gear. These are slightly lighter than heat shields but have a lower lift to drag ratio. Also you can land on them. -The small aerodynamic nose cone. Doubles as node occlusion for a fairing, but the required angle means it has less occlusion power. Very light but relatively low lift to drag compared to the above options, probably still a pretty good choice for this challenge. -Fairings. This one's a free optimization because our existing crafts can easily be adapted to take advantage of this effect. It actually ends up hurting the partial run I did yesterday because the small magic wing effect is canceling out some of my wing lift. -Flags. In 1.12 this is fixed, but in 1.11 (which I play for mostly unrelated reasons), flags are the most overpowered part in the game. They have incredibly high lift and also zero drag, meaning that your only source of drag will be the body drag from your hull. Additionally propellers with flags are extremely broken - I've created flag prop crafts with TWR of over 100 before, as well as pulling one all the way to Kerbin escape velocity while still in the atmosphere. Flags also make for great single-use landing gear and they're very light. Actually I believe that my original entry also had offset blades by exactly the same amount. I just reduced mass and optimized the characteristics of the motors.
  6. Well, my computer didn't crash, but sometime during the night my frames dropped through the floor and I barely made any progress. Currently KSP is closed but I might try flying it some more today. Not at all - I'm not offsetting the props enough for the torque flip to take effect. Instead, I'm simply reducing the radius of the propeller, reducing the torque needed to accelerate it up to speed. The same effect would occur in a real life propeller. There is no free energy. The lift and drag points of the prop are still on the same side of the axis of rotation. Also the prop blades aren't clipped inwards into each other - they just appear to be attached end to end. You've touched on the main reason why it's so hard to determine what counts as cheaty in KSP. Everyone has a different threshold for what mechanics they'll be willing to abuse, whether it be part clipping, root fairing body craft, magic wings, or even Kraken drives. I think that offsetting the props one tick inward isn't too cheaty, as you aren't getting any torque reversal (No free energy) and thus the motor still requires some energy to operate. Again, the energy cost is reduced, but that matches the real world. Meanwhile, offsetting them further to create infini-props would be too cheaty for me as you're getting free energy. And it seems that you think any amount of prop offsetting is cheaty since you're reducing the required torque to drive the prop. I don't think there's any way to reconcile this without someone changing his (or her) opinion. Huh, I never realized that basic fins actually have a better mass ratio. Interesting, but this probably won't be useful for the SSTO craft I like because of the fin's terrible heat tolerance.
  7. One final update before I go to sleep: 20 electric charge used. Around 81 degrees of longitude have been covered. That's about 848 km. Total estimated range is now 4241 km. The craft seems to be perfectly stable at this height and speed, so I think I'll go to sleep and see where it's at when I wake up. Hopefully my computer doesn't crash.
  8. Actually I'm almost certain that KSP was simply rounding the current down to zero. Right now I'm at 4% thrust limit and drawing about 0.01 units of charge every 5 seconds. Meanwhile, in my earlier picture, I was at 3% thrust limit, which meant I should have expected to draw 0.01 units of charge every 7-8 seconds. But I went a full minute and didn't see any current draw. Small update: I'm over the continent where my last mission landed. I'm actually still increasing speed slightly, so this next estimate is again an underestimate of the maximum range of this craft. 91.89 / 0.00206 * 89.8 = 4006 km remaining. Maybe we could have an alternate leaderboard for using only ten units of electric charge?
  9. And... we've finally done it! I found that flying higher is actually beneficial, as I can fly faster for the same drag and thus the same motor output power. This only really breaks down when I start reaching Mach effects around the propeller, where I'll want to fly lower to take advantage of the higher speed of sound. However, Mach effects are insignificant here. 0.00204 electricity used per second. 95.48 / 0.00204 * 84.6 = 3960 km. I wouldn't describe anything I'm currently doing as a cheat. I'm not taking advantage of any magic wing effects - in fact, I'm doing the opposite, as I'm flying at a -1 degree AoA right now and so I actually get a penalty from fairing body lift. The props aren't spinning infinitely and in fact take a positive torque to maintain. They're slightly offset inward, but I'm not generating any phantom torque. I don't know what happened with the zero power draw, but it felt a bit too cheaty for me, so I purposely increased torque limit in order to draw a measurable current.
  10. Okay, this is getting ridiculous. My power usage is so low that KSP flatly refuses to tell me the motor is drawing any power at all. In fact, after a full minute, KSP tells me that less than 0.01 units of electric charge have been used. Doing some quick back of the napkin math: Assume 0.01 electric charge used per minute (Upper bound of what's actually possible given my readouts) 9974 minutes * 60 seconds * 55.6 m/s = 33273 km The problem is that this will take a full week to actually finish! My computer probably can't go that long without blue screening. So this is firmly in the realm of a theoretical mission. Increasing the throttle a little bit, finally I start to see some power draw! Each motor is drawing 1.03 milli-units per second, or 2.06 milli-units per second (0.00206 u/s) in total. This translates to a flight time of 48252 seconds, or about 13 hours. This is actually pretty reasonable, but still far too long for me. This also implies a max range of 3339 km. A full circumnavigation of Kerbin is 3768 km. It's tantalizingly close!
  11. Interestingly enough, single blade propellers do exist in the real world: But I suspect they'd be impractical in KSP due to the difficulty of balancing them. Have you tried further reducing motor size? A smaller motor would have less weight and draw less power. You'd need to have a higher torque limit, but that is likely a good thing - it gives you finer control over your overall torque. Another thing you could do is angle your fairing upwards so you get some body lift. It'll be minimal but it will help reduce drag.
  12. A slightly more Kerbal way to do this (at least on a vacuum body) is to have the mothership orbiting extremely low above the surface and plant the flag when it's within physics range. This probably isn't practical but would be really funny. This wouldn't work on Duna but would be fine on Ike.
  13. By the way, increased drag from denser air probably isn't a factor here, as all else equal, higher drag will mean higher lift so your plane will simply reach equilibrium higher in the atmosphere. I suspect it's due to two things: -Colder air means lower speed of sound, so you're shifting the Mach curve. If you're using a supersonic jet engine at max speed, this means your max speed is reduced. -Centripetal force is reduced because you're farther north, so you need more lift to cancel out gravity - which means more drag, but not because the air is denser
  14. Well, I've got this: Airspeed = 52.30 m/s Electricity usage = 0.0032 u/s Electricity remaining = 86.47 This translates to 27022 seconds of powered flight remaining, or 1413 km. And that's not including the initial bit of flight to get here, or the glide down to the ocean. I am completely unwilling to fly for 7.5 hours even with an autopilot. But this shows that a twin engine design is still quite capable! (I went back to two engines because a motor casing is only 18 kg and this way Smart A.S.S. can actually fly the craft without completely dying).
  15. Oh no If you continue pushing the bar I'll have to either graciously bow out of this challenge, or begin to abuse aero exploits
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