# Kerbin Circumnavigation 1.2 - Aviator Challenge Continuation

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11 hours ago, daniel911t said:

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

... 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.

That's quite an attractive design you've got there.  At 14km altitude, the circumference is more like 3856 km.  The rotation of Kerbin is irrelevant, since your speed is relative to the surface.  So your circles will be 51,120km / 3856 = 13.25.  If you include the overshoot and the time spent at lower speed, that means you got 13 circles.  Nicely done!

EDIT: there's one correction that needs to be made.  Kerbin days are only 6 hours long!  So 2 days, 5 hours, and 11 minutes is 17:11, or 61200+660 =61860 seconds.  So your total distance is 16,516km, which works out to 4x around.

Edited by zolotiyeruki
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13 hours ago, zolotiyeruki said:

That's quite an attractive design you've got there.  At 14km altitude, the circumference is more like 3856 km.  The rotation of Kerbin is irrelevant, since your speed is relative to the surface.  So your circles will be 51,120km / 3856 = 13.25.  If you include the overshoot and the time spent at lower speed, that means you got 13 circles.  Nicely done!

EDIT: there's one correction that needs to be made.  Kerbin days are only 6 hours long!  So 2 days, 5 hours, and 11 minutes is 17:11, or 61200+660 =61860 seconds.  So your total distance is 16,516km, which works out to 4x around.

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?

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Before I try with this again, can you confirm that this 4.6t mission is a failure?..

What happened was that when I was on the final approach the front gear wouldn't lower because it was stowed in the shield. So I had to blow the shield to get the wheel down about 250m from landing.

I'm assuming that means I dropped some parts and so failed, right?

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Foxster,
How are you getting air into your engine?

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3 hours ago, daniel911t said:

Foxster,
How are you getting air into your engine?

A cone intake rotated and clipped inside. My bad?

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7 hours ago, Foxster said:

Before I try with this again, can you confirm that this 4.6t mission is a failure?..

What happened was that when I was on the final approach the front gear wouldn't lower because it was stowed in the shield. So I had to blow the shield to get the wheel down about 250m from landing.

I'm assuming that means I dropped some parts and so failed, right?

I'm afraid so.  See also below.  FWIW, I think there's enough torque in the cockpit that you could have balanced on the two wheels on your landing.

2 hours ago, Foxster said:

A cone intake rotated and clipped inside. My bad?

It sounds like you attached the intake to the back of the engine.  If so, yeah, that's against the rules as well.  Also, how did you fit enough fuel in that craft to circumnavigate?  I don't think the 200 LF in the wing tanks is enough with a RAPIER.

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38 minutes ago, zolotiyeruki said:

I'm afraid so.  See also below.  FWIW, I think there's enough torque in the cockpit that you could have balanced on the two wheels on your landing.

It sounds like you attached the intake to the back of the engine.  If so, yeah, that's against the rules as well.  Also, how did you fit enough fuel in that craft to circumnavigate?  I don't think the 200 LF in the wing tanks is enough with a RAPIER.

OK. I've fixed the front gear so that's not a problem now. I'll have to give a bit of thought to the intake. Might try a bunch of radial intakes and see what that does.

There was plenty of fuel with 200 LF. There was 30+ left at the end. The craft is really low drag and I flew it at 25km at 1/2 throttle (~1725 m/s) so fuel consumption was really low.

Edited by Foxster

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Think I'm there OK with the #2 that weighs in at 4.657t. Once around in 40 mins 45 secs...

Album: http://imgur.com/a/vUZ3C

Had a slight topple at the end because I forget to set up the wheels for braking and steering but nothing broke.

You can see there was loads of fuel with 200 LF in the wings. There was ~64 left at the end.

Here's the craft file if anyone wants to try it: https://www.dropbox.com/s/k9s9d0imhftzu03/Fast high altitude 9.craft?dl=0

There's definitely a couple of minutes that could be shaved off with this craft. It could fly a little lower and so faster, using up some of the 64LF margin. Thing is though getting that F3 shot at the end, which means no F5/F9 so you have to nail the landing, if you mess it up then you have to start all over, which is too frustrating for my limited attention span.

Edited by Foxster

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1 hour ago, zolotiyeruki said:

I'm afraid so.  See also below.  FWIW, I think there's enough torque in the cockpit that you could have balanced on the two wheels on your landing.

It sounds like you attached the intake to the back of the engine.  If so, yeah, that's against the rules as well.  Also, how did you fit enough fuel in that craft to circumnavigate?  I don't think the 200 LF in the wing tanks is enough with a RAPIER.

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.

Edited by daniel911t
oops
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20 minutes ago, daniel911t said:

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.

Fair point--in the previous iteration of this challenge, I flew at 24-27km altitude and 1600+m/s, and my fuel consumption got down to something like 0.04/s.  With a smaller/lighter craft and higher altitude, 0.01 might be possible.

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34 minutes ago, Foxster said:

Think I'm there OK with the #2 that weighs in at 4.657t. Once around in 40 mins 45 secs...

Album: http://imgur.com/a/vUZ3C

Had a slight topple at the end because I forget to set up the wheels for braking and steering but nothing broke.

You can see there was loads of fuel with 200 LF in the wings. There was ~64 left at the end.

Here's the craft file if anyone wants to try it: https://www.dropbox.com/s/k9s9d0imhftzu03/Fast high altitude 9.craft?dl=0

There's definitely a couple of minutes that could be shaved off with this craft. It could fly a little lower and so faster, using up some of the 64LF margin. Thing is though getting that F3 shot at the end, which means no F5/F9 so you have to nail the landing, if you mess it up then you have to start all over, which is too frustrating for my limited attention span.

I love it!  If you were to leave out 60 LF from the tanks when starting, that'd save another 300kg, giving your the potential for faster acceleration and higher speed.  I wonder, with the torque from the capsule and the low mass, if you'd even need control surfaces as well.  Save another 80kg...

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10 hours ago, zolotiyeruki said:

Fair point--in the previous iteration of this challenge, I flew at 24-27km altitude and 1600+m/s, and my fuel consumption got down to something like 0.04/s.  With a smaller/lighter craft and higher altitude, 0.01 might be possible.

So, I'm trying to beat my previous record (12 circles on 1.1), and my craft is bouncing around 1650m/s and 28km.  It speeds up and climbs (at 0 pitch) until the engine flames out, descends, relights the engines, and repeats the pattern.  I'm not sure what the average fuel consumption is, but when the engine is lit, it's about 0.05, and a bunch of the time, it's coasting.

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Last go, I don't have the patience for more. Once around in 38mins 49secs in the same craft but flying at 20km. Still 25LF left at the end.

The temperature was the limiting factor, with the wings just about ready to melt at the end, 2395° with a max of 2400.

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40 minutes ago, Foxster said:

Last go, I don't have the patience for more. Once around in 38mins 49secs in the same craft but flying at 20km. Still 25LF left at the end.

The temperature was the limiting factor, with the wings just about ready to melt at the end, 2395° with a max of 2400.

Impressive!  Any chance you have an album to go with that screenshot?

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Just now, zolotiyeruki said:

Impressive!  Any chance you have an album to go with that screenshot?

Nope. But despite my protestations, I am working on a #3. If it works out I'll do an album for that.

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LOL!  I just finished up my Voyager entry.  14x around.  Left it running overnight.  Used up every last drop of fuel to get back to the runway.  Pics coming tonight.  The craft started off at something like 17.4T and ended at 5.25T.  It was so floaty at the end that the landing speed was about 30m/s.

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Anyone know how to get >1750 m/s with a RAPIER?

At any altitude when I hit that speed the engine flames out and then kicks back in, limiting the craft to that speed.

I've tried adding more intake but that doesn't do the job.

Update: I've done some digging around and that's the max speed possible for an LF+air aircraft - unless, of course, you know different?

Edited by Foxster

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Is TweakScale allowed? It's technically a building mod, but it doesn't give you better parts than usual

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Almost definitely my last attempt at a speed run with a little 3.893t craft @ 38 mins 15 secs ...

Album: http://imgur.com/a/VrZHg

Note that there is nothing attached to the back of the engine. Its just a bit of the fairing poking out.

One major contribution to heat control that allowed for a fast climb, cruise and landing was to have the front landing gear out forward. It has a temp max of 2600°.

Edited by Foxster
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I just may have a contender. Just gotta tweak it.

Did a quick run for 26 minutes. It held the speed, took the temperature. I'll fine tune the aerodynamics but she's faster than my KSP 1.05 plane (It did 1728 m/s at 21,000 m).

EDIT: Managed to coax it to 1742.

Edited by GDJ

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7 hours ago, Foxster said:

Anyone know how to get >1750 m/s with a RAPIER? ...

Update: I've done some digging around and that's the max speed possible for an LF+air aircraft - unless, of course, you know different?

That's about right.  I think I've seen 1753 thrown around as the maximum number.  I know I've hit 1751.

5 hours ago, RedPandaz said:

Is TweakScale allowed? It's technically a building mod, but it doesn't give you better parts than usual

Given the razor-thin margins involved with some of the builds, I have to say no here.  Even something as simple as a double-length LF-only tank could make a difference (less flexing in the craft leading to better occlusion and lower drag).

5 hours ago, Foxster said:

Almost definitely my last attempt at a speed run with a little 3.893t craft @ 38 mins 15 secs ...

Album: http://imgur.com/a/VrZHg

Note that there is nothing attached to the back of the engine. Its just a bit of the fairing poking out.

One major contribution to heat control that allowed for a fast climb, cruise and landing was to have the front landing gear out forward. It has a temp max of 2600°.

Talk about optimizing to the extreme, but I'm a bit concerned about the amount of clipping involved here.  Out of curiosity, where's your fuel?

Hmmm.  I thought there was a rule about the kerbal needing to be in a proper capsule/cockpit, but there wasn't.  Now there is   I'll let this one slide on that point, though.

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54 minutes ago, zolotiyeruki said:

Talk about optimizing to the extreme, but I'm a bit concerned about the amount of clipping involved here.  Out of curiosity, where's your fuel?

Hmmm.  I thought there was a rule about the kerbal needing to be in a proper capsule/cockpit, but there wasn't.  Now there is   I'll let this one slide on that point, though.

Yup, the clipping had me a tad uncertain. It is only the fairing that clips but it clips a few things. I was trying to get it to close around the RAPIER but it just wouldn't, I can maybe make that happen with a bit of messing about.

The fuel? There are three 50 unit tanks inside the  fairing in front of the service bay.

Basically, if you can get a craft to 1750 m/s quickly and maintain that then this challenge becomes about the take-off and landing.

Edited by Foxster
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2 hours, 6 minutes, 35 seconds.

Val took this weird thing around once.  'Climbed straight out from the runway.  Took awhile; had to F9 the landing.  One Juno FTW.

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1 hour ago, klond said:

2 hours, 6 minutes, 35 seconds.

Val took this weird thing around once.  'Climbed straight out from the runway.  Took awhile; had to F9 the landing.  One Juno FTW.

Yup, that looks good to me.  You've been added!

I promised my own Voyager entry, and here it is:  http://imgur.com/a/SfRaJ

I let this one run overnight (and then some).  Landed without so much as fumes in the fuel tanks.

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Oh, go on then, one last try with a capsule (38m20s)...

Album: http://imgur.com/a/kqbbe

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