daniel911t

You guys are amazing! I tried and tried and just couldn't control heat adequately. I need to watch your videos and learn... I'm still trying for the distance record... However, I think I was already pretty near the best possible performance with a wheesly. I've been experimenting with Goliath, but the drag is just shocking... can't seem to get consumption down to anything near Wheesly. I need to look and see if there's a modded category... I think I could really do something impressive with just procedural wings. (Keeper of the challenge? Thoughts on wings?)

When I've tried my speed run attempts I've actually seen some things that I thought were near impossible - like at 28Km and Mach 5.7 a RAPIER had a fuel consumption of 0.01/sec. I've never actually seen a jet engine run more efficiently.

Foxster, How are you getting air into your engine?

Oh my! That really changes the calculations! I can't believe I didn't think about the length of a day being different! Does that mean everyone's been miscalculating?

I've tried some of the solutions... -The inline heat shield delayed heat soak and destruction, but didn't eliminate it. -Having ablator onboard does help - although not much. I initially added 80 units, but discovered that it was being consumed at a very low rate. I reduced it to the 20 unit minimum and haven't run out before the explosion. -Position of the command pod helps. Moving it back delays heating, but it's still heat soaking and failing. The aircraft is also slower due to less optimized CG/CoL, Even with the wing moved aft to compensate. There is a pretty significant design benefit to having balanced fuel usage at both sides of the CG. -For much of the flight, the critical part is the intake, but very slowly heat builds in the command pod, at the rate of about 1 degree per second - eventually it becomes critical, then all I can do is watch as the temp slowly climbs to explosion - usually just as I'm passing the desert. (about 3/4 of the full lap) I'm still trying to work out the effects of altitude. The old rule of thumb I know is "when heat is a problem, climb". I've tried cruising everywhere from 21Km to 28Km, and the biggest difference I've noticed is a reduction in top speed as I climb beyond the optimal altitude (about 23Km I think), but the heat issue does not seem get better or worse with altitude changes, independent of speed changes. (within reason - if I descend to 15km I essentially spontaneously explode) Any other tricks, tips, or ideas?

I made a second attempt, this time going for distance! The new plane was built around the second most efficient engine, the little Wheesley. This aircraft required several step climbs, starting at about 8KM, ending at 13,750M. I really, really, really tried for 14KM, but every time I got there, speed started slowly bleeding off and it was clear I couldn't hold it. So... now I have to do the math in public and I'll let you decide what seems more accurate for the number of laps: Time traveled: 2 Days, 5 Hours, 11 minutes (53hrs, 11 min) or, ((53*60)+11)*60 = 191,460 seconds in flight Highest speed: 267m/s Approximate distance: 191,460 seconds * 267m/s = 51,119,820m Kerbin circumference: 3,769,911m Circumnavigations: 13.56 ... however, I landed back at KSC, and only overshot by a few Km. So a whole number would make sense. Let me publicly do the alternate: Ground distance traveled: 33,462,023 divided by 3,769,911 = 8.87 circumnavigations So... I think the 13 number is closer to truth. Anybody care to help me figure how far it really was? (especially in light of the correct answer being known to be a whole number!) EDIT: I'm kinda dense - while flying for two days, Kerbin would make two full rotations underneath me. Depending on how they calculate it, that could remove more than 2 revolutions from my total. That adds weight to the larger number.

I'm trying to complete the Kerbin Circumnavigation speed challenge and I'm having persistent problems with aircraft that heat up and explode about halfway around the world. The part that's overheating is always the command pod, which is strange because it's in the middle of the aircraft. The basic fuel tank in front and in back of it does't overheat. It always does this: I installed some small radiators - they typically register as the coolest part of the plane, but they don't seem to make much difference. I also adjusted the angle of incidence on the wings, which dramatically reduced fuselage heating, but for some reason the command pod still overheats, even when the rest of the craft is nominal. I've seen people get the sustained high speeds and not melt, but I just can't seem to manage it. What are the tricks and secrets?

Here's my go at the first level: Also, got 6 revolutions. Wings full of fuel. First time around the globe. HI KSC! *wave* After landing - honestly not sure how many times I made it around... I think 4 ish. I'll have to do the math. However, the endurance was remarkable: 49 hours and change. (with fuel left over) Edit -Calculator says 6.019 revolutions. I did overshoot and come back to land heading 270 - that's the .019 I assume. beauty shot Back to the drawing board for the speed run.

Martian, Great run! I see you were at about an hour on flight time too.

No SAS on mine! It isn't even installed. I set up the Atmosphere Autopilot for a (semi) constant rate of descent. I adjust to keep airspeed constant. So long as I'm in the -1 to -2m/s range and not accelerating, it was seeming to glide forever. With my method spelled out... I made no attempt to optimize my aircraft. Being a paper airplane challenge, I thought I should model a paper airplane. If the actual challenge was max glide with only 16 sepratrons, my aircraft would have looked much different.

Is it possible that engineers increase the efficiency of radiators too?

Yeah, but I was surprised to see that I had to - I initially thought they were passive.

If you look at my pics you'll see that the ISRU settled in at about 1100, even with the two large radiators. I'm frustrated that their cooling ability doesn't seem to be impacted by airflow. I would expect much, much greater cooling efficiency with fluid flow over the radiator and with a greater delta T. (it should be much cooler at 5000M than at the surface) Sadly, it doesn't seem that KSP works that way. I didn't notice any difference in cooling performance under any circumstances.

I decided to try again - this time with more wing and only a pilot. fuselage is the same as my first attempt, but the wings and heatsinks were changed. It took a while to start making enough fuel, and I had to actually plot a graph to find the absolute bottom of my power curve 60 m/s -13.6 kn thrust required 65 m/s - 13.3 kn 68 m/s - 13.2 kn 70 m/s - 12.8 kn 75 m/s - 12.6 kn 77 m/s - 12.3 kn 80 m/s - 12.6 kn 85 m/s - 12.7 kn As soon as the numbers started climbing again I knew there was no point going any faster - form drag (drag created by the airframe) goes up with the square of the speed, so as soon as power required started to tick up, I knew I was getting away from max efficiency. When going slow, induced drag is dominant (drag from making lift), as you speed up, less AOA is required to make the same lift, therefore less induced drag, until form drag comes up and takes over. The magic spot where the curves for form drag and induced drag meet is the most efficient. It's somewhat counter-intuitive, but if you go slower than that magic spot, it actually requires more power the slower you fly. For this airplane that magic point is just about 77m/s. This thing flies forever. I got over an hour of flight time out of just the round 8 and ore. Right before finally running out of fuel. Super fun challenge! I'm thinking multi engine next. I have serious doubts about SSTO, I just don't think the power's there, unless you can use a larger holding LFO tank...