Kerbin Circumnavigation Challenge - updated for KSP 1.10

[Mars-Bound Hokie]

Were you, by any chance, inspired by my old "Around the World in 80 Minutes" challenge from last year?

 

 

[Lt_Duckweed]

4 hours ago, zolotiyeruki said:

Does attaching wings to objects inside the fairing mess with the aero or thermal?  I seem to remember there being some odd behavior about that.

It does not.  The wings will behave entirely normally.

[zolotiyeruki]

10 hours ago, Mars-Bound Hokie said:

Were you, by any chance, inspired by my old "Around the World in 80 Minutes" challenge from last year?

 

 

Nah, versions of this challenge date back at least to 2014:

 

[Mars-Bound Hokie]

Well, in any case, I'll enter the Velocity Division. I'll use the same plane I used to kick off my "80 Minutes" challenge.

• I had to fly it again due to the 1.10 rule, and I originally flew December last year.

 

• "Bill's Car" right before takeoff
• Bill's in the cockpit.
  • He doesn't need to worry about not being able to control the plane, for he has a probe core.

 

• Working on a cruising speed and altitude.

 

• Flying at 18,500 m altitude at 1,350 m/s
  • When I tried 1400 m/s, I eventually blew up from overheating.
• Used MJ Autopilot for most of the flight.

 

When the cockpit heat meter got too high, I had to cut the engine for a bit so that it could cool down while the plane glided. While it saved Bill's life, it cost me some precious time.

 

• So close to the runway.

 

• TIME: 53 minutes, 35 seconds
  • So close to beating my previous time.
    • Stupid aerodynamic update.

Edited October 23, 2020 by Mars-Bound Hokie

[zolotiyeruki]

Cool, cool!   Er.....I mean.....nicely done!  And without Rapiers, no less!

[zolotiyeruki]

Alright, I finally have my first entry for the Voyager division.  I managed 19x times around!  Woohoo!

https://imgur.com/a/Ms6hE72

[linuxgurugamer]

I'm working on a video & written story to go along with my next entry.  Taking a little longer than expected, making videos is very timeconsuming

[linuxgurugamer]

Been quiet here.  I hope to complete me next entry tomorrow.

[linuxgurugamer]

Ok.  Just finished it, will get the details in the next few days.  38:53 was the best I was able to do.

Available on KerbalX:  https://kerbalx.com/linuxgurugamer/Mach-V

Grr.  Video shows 38:54, I'll have to do it one more time.  At least it will get me tied for 2nd.  It actually landed with parachutes (made a slight miscalculation as to height), will be trying again in a day or so

 

Edited December 4, 2020 by linuxgurugamer

[zolotiyeruki]

Wow, that's a lot of engines, and well done!  You've been added to the leaderboard.  If I were in a pedantic mood, I would disqualify your entry on a number of points:

1) you have RAPIERs, but no preflight screenshot showing no LF
2) your screenshot at the end does not show the craft at a full stop
3) you are not within 1.1km of the KSC
4) No F3 screenshot
5) No screenshot on the far side of the planet

[Mat2ch]

Well, I don't know if Stratzenblitz75 applied, but, uhm he made 19.

https://www.youtube.com/watch?v=YXzmnSdrM1k

[zolotiyeruki]

He hasn't posted in here that I'm aware of.  Going that far on a Goliath is impressive, especially with no autopilot, and managing heat with flags is a new trick I've never heard of.  That craft had well over 1,200 parts, though.  Yeesh, how on earth did his computer handle that?  Rigid Attachment, maybe?

[camacju]

Is this challenge still accepting submissions? I'm thinking a slight modification of a SSTO I've made should be able to do a lot of runs around Kerbin.

By the way I was watching Stratzenblitz stream his Goliath endurance run and he was using Mechjeb to keep straight. Also he has a pretty good computer.

[camacju]

@zolotiyeruki If you're still taking submissions, here's my entry for the Voyager division.

This craft is basically a long range SSTO but with the nuclear engine removed. Since it's optimized for low drag and good mass ratio, it's actually quite good at endurance, even though that's not the primary purpose.

Craft in VAB. 35 tons, six strakes. No clipped parts at all, no node offsetting, everything is attached how it looks.

Laps 1-10

Spoiler

Letting the Rapier spool up on the runway is less efficient but easier to take off.

Picking up speed at sea level until 400 m/s

Climb to cruising altitude

Level off at 21 km. Now, all that's needed is to point at the horizon, turn on time warp, and let the craft do the rest.

Lap 1

Lap 2

Lap 3

Lap 4

Lap 5

Lap 6

Lap 7

Lap 8

Lap 9

Lap 10

At this point the craft has been flying for over a full Kerbin day and has just over 38% of its fuel left, but the craft cruises higher as fuel drains, which means less drag and less fuel consumption. At this point I calculated that the craft could last for over 10 more laps, but that was a simple linear estimation. The true range of the craft is higher.

Laps 11-19

Spoiler

Lap 11

Lap 12

Lap 13

Lap 14

Lap 15

Lap 16

Lap 17

Lap 18

Lap 19

Now the craft has been flying for two Kerbin days and done 19 full circumnavigations. I've tied the endurance record here, but I've still got some fuel left - let's see how much further this craft can go.

Based on fuel usage I calculate here that the craft can definitely do four more laps and possibly a fifth depending on how much further fuel consumption can be reduced. So 23 laps is very possible.

Lap ??-??

Spoiler

Lap 20 and a new record

Lap 21

Lap 22

Cutting throttle over the coast to the east of the Dessert Airfield. I glide the rest of the way to KSC.

Based on fuel consumption I would probably end up running out of fuel over the opposite coast of this continent and it would be a difficult glide to KSC. It probably would be possible but it was getting late and I was getting tired.

Descent to KSC

Final approach

Landed - 23 laps, 2.5 days, with fuel to spare!

 

[zolotiyeruki]

Dang, color me impressed.  What angle of incidence did you use on your wings?

I've added you to the leaderboard.  You've earned it.

[camacju]

2 hours ago, zolotiyeruki said:

What angle of incidence did you use on your wings?

5 degrees. Not sure whether that's optimal but that's the minimum angle snap available so that's what I used

[camacju]

@zolotiyeruki Here are two more submissions for this challenge.

The first is a new record for fastest circumnavigation, in 37min 57sec. Could be faster with more optimized wings but I'll take it for now.

Spoiler

In SPH. I don't think this violates any clipping rules but please let me know if it does.

On runway

Beginning climb

Halfway

Approaching KSC mountains

Beginning dive

Practically scraping the cliffs of K2

Another shot

 Heat shields have interesting aero properties when one or both of the bottom nodes are occluded. I use this to generate high aero forces, causing me to slow down quickly.

Final boost down to the ground before cutting the engine

Landed at or before 37:57

The second is the lightest craft that I could get to circumnavigate, at 2.01 tons. I saw that in the previous incarnation of this challenge people were trying low-mass submissions.

Spoiler

In VAB

On runway

Picking up speed

Leveling off

Halfway

Approaching K2

Landed

 

[swjr-swis]

6 hours ago, camacju said:

The second is the lightest craft that I could get to circumnavigate, at 2.01 tons.

Nice, but we both know you can do better than that. No holding back now!

 

Based off an older entry of mine for a different efficiency challenge, and using no drag-reduction trickery at all, I can get a 1.885 t plane around the planet.

Spoiler

The MinCN-1885, a single-Juno 1.885 t take off weight plane for doing a Kerbin circumnavigation at mach 2. All parts exposed to regular drag... iow even better results are possible.

Ready for take off with 91 units of LF in the tanks.

Zooming off the runway. The single Juno is powerful enough for this tiny plane to go supersonic.

Halfway around Kerbin.

Approaching KSC, time to cut throttle and start our descent.

Landed safely on the runway after a full circumnavigation in 1h53m, with still 5.5 units of LF left in the tanks.

If this can be done with fairly 'standard' build methods, surely with some additional drag-negating techniques we can get even lighter.

 

[camacju]

Well, there is the restriction that I have to use an aircraft cockpit rather than a command pod. If I remember correctly the lightest cockpit is about 300kg heavier than the mk1 command pod. So that more than makes up for the difference.

Also you can see the effects of the aero optimization in that I only used 66 liquid fuel while you used 85. 
 

edit: the mk1 command pod is 840kg and the mk1 in-line cockpit is 1030kg. So if I were to switch the cockpit I would have a lighter craft. 

Edited September 4, 2021 by camacju

[zolotiyeruki]

Command pods are allowed (I've used them plenty).  It's command chairs that aren't.

For that speed run, it appears that there's a fair amount of clipping going on.  That isn't allowed.  Also, there's lots of.....stripes? around the cockpit and RAPIER.  What's going on there?

[camacju]

Wow I completely misread the rules. I guess I’ll swap the cockpit out for a lander can and shave off a lot of mass. 

For the speed run, none of the fuel tanks are clipped into each other or any solid part but they do stick out of the fairing. However I left some empty space in the fairing so the total volume is still realistic. If this is a problem then I’ll just rearrange the fuel tanks and fly the mission again  

The stripes are probably due to intersections of the polygonal meshes with the cockpit, rapier and fairing. I could make the fairing narrower or wider and the stripes would disappear. 

[zolotiyeruki]

The spirit of the challenge is that the craft should be something that could be reasonably constructed in realspace.  Tanks poking out through the fairing is something that exploits the physics engine, and a fairing that's z-fighting with most of your fuselage probably  needs to be made ever-so-slightly wider.

[camacju]

1 hour ago, zolotiyeruki said:

The spirit of the challenge is that the craft should be something that could be reasonably constructed in realspace.  Tanks poking out through the fairing is something that exploits the physics engine, and a fairing that's z-fighting with most of your fuselage probably  needs to be made ever-so-slightly wider.

New submission - circumnavigation is 37 minutes 3 seconds

No clipping

On runway

Speed!

Halfway

This was a Mechjeb-less flight so I'm a bit off target from KSC

Death dive down to sea level, deploy gear and flare at the last possible moment. This took a lot of quicksaves

Landed

[zolotiyeruki]

How did you get to over 1900m/s?  RAPIERS flame out at 1753 or so.

[camacju]

48 minutes ago, zolotiyeruki said:

How did you get to over 1900m/s?  RAPIERS flame out at 1753 or so.

RAPIERs don't flame out at a set speed - instead, they flame out at a set Mach number, which is around Mach 6. The speed of sound is different depending on the time of day, latitude, and altitude. Therefore a RAPIER can go a lot faster if it's near sea level on the equator at noon. I launched at nighttime because the earliest part of the flight is the fastest, so I would spend more time on the other side of the planet and get greater benefit from the speed of sound bonus during the daytime.

In my screenshots, you can see that the 1900 m/s screenshot is at Mach 5.7 at low altitude, while my third-to-last screenshot is at Mach 5.7 at a higher altitude. This is over a 200 m/s difference. You can see from AeroGUI that the speed of sound is different.

I've gotten a RAPIER to 2110 m/s surface speed before, and I know someone else on Discord who's gone even faster. It's all a matter of Mach number.

By the way, are we allowed to deploy fairings for speed runs? If so, I think I can easily beat 37 minutes.