Kerbin Circumnavigation 1.0.2 - Aviator Challenge

[imthebait]

I'm confused. The circumference of Kerbin is 3,769,911m. Your distance is showing 3,939,677. That distance is very consistent with one circumnavigation. Kerbin rotates in the direction you were travelling meaning, the distance would be even further than 3,700km. In 2 hours, it rotates 628km. So, somewhere around 4,300km would be a reasonable distance. I could buy the 3,900 if it were one, but how did you get two circumnavigations? I'm not saying you didn't mind you. I've already seen some strange numbers coming from these flights. It just doesn't make sense though. Now if you managed an average of say 1,100m/s over 2 hours that would be 7,900km which does make sense for 2 circumnavigations. I'm just curious why the F3 is showing something very different.

The time for the speed you were travelling, that sounds about right. That F3 screen has me breaking out the calculator tho. Did you perhaps F5/F9?

I think i figured it out, if you take the distance of the flight taken as a circumference and get the radius, it comes out to 627019, which just so happens to be 27,000 meters above the surface of kerbin, even though i flew at 22,500m you could easily add some distance for variations in flight. pilot assistant had a tendency to be a few tenths of a degree off, which after two circumnavigations could add up.

Anyways, just a thought.

Still working on my entry for velocity circumnavigation.

[Fengist]

I think i figured it out, if you take the distance of the flight taken as a circumference and get the radius, it comes out to 627019, which just so happens to be 27,000 meters above the surface of kerbin, even though i flew at 22,500m you could easily add some distance for variations in flight. pilot assistant had a tendency to be a few tenths of a degree off, which after two circumnavigations could add up.

Anyways, just a thought.

Still working on my entry for velocity circumnavigation.

Correct. But you made 2 circumnavigations. So, you divide that by 2. Your first lap shows you traveled some 1,900km. If you take that as the circumference you'll get a radius of 300ish km. According to the wiki, it's 600km.

Now, the only thing I can imagine is, either the wiki is wrong or, the size of Kerbin has shrunk by half!

[imthebait]

So, i finished my velocity enter, the Raptor 1 is capable of fairly impressive speeds, traveling at an average rate of 1300 m/s this aircraft is fast.

while i am pretty sure i can get my time down by about a minute by refining my takeoff and landing, i think this is approaching the speed limit on turbo's, unless i can get up around 25km while still traveling above 1300, i expect anything else may just burn up

Top Speed: 1323

Time spent: 54:20, or 54:10 if you're counting time to remember to press f3

http://imgur.com/a/Cm39X

Im working on the 3 circumnavigation aircraft, if anyone wants to know it takes about 700 fuel for one circumnavigation at this speed

[Mic_n]

as far as altering your pitch in flight... I'm presuming that's due to the centre of gravity shifting as you burn fuel? If that's the case, you should just be able to shift fuel between front and back to rebalance it.

You seem like you know what you're doing, but from memory it's alt + right-click on the fuel tanks in question, you can then use the "out" and "in" buttons on each slider as needed. Note that you can push from "one to many" or pull from "many to one" with that, too..

[imthebait]

as far as altering your pitch in flight... I'm presuming that's due to the centre of gravity shifting as you burn fuel? If that's the case, you should just be able to shift fuel between front and back to rebalance it.

You seem like you know what you're doing, but from memory it's alt + right-click on the fuel tanks in question, you can then use the "out" and "in" buttons on each slider as needed. Note that you can push from "one to many" or pull from "many to one" with that, too..

It had more to do with angling the engines relative to the aircraft, but ive found that if i just forgo stability and put cog right under cof the aircraft flies pretty level, but she is very unstable so dont stall

Edited May 18, 2015 by imthebait

[Prof. Endwalker]

Doing this mission as I speak. Gotta love the Spirit of St. Louis! I'll keep posted as I reach new goals.

[imthebait]

Good luck mate, best of luck to your craft

[imthebait]

I have finally finished the 3 lap challenge, the Eagle has landed and I can now say I never want to spend that much time watching my plane on fire ever again, while I'm pretty sure I could do 4 if I really put my mind to the challenge, cruising speed was 1200+, but altitude varied until I got done with the first circumnavigation, i had too much fuel to fly higher while still maintaining speeds above 1200,

Eagle 1

Top speed: 1253m/s

Time elapsed: 2:44:53

Cruising altitude: 21000-22500m

http://imgur.com/a/YWoyt

Thanks all, I'm going to be monitoring this thread for really cool aircraft so i look forward to seeing other peoples submissions.

Fly Safe, oh wait this is KSP never mind, have fun!

Edited May 19, 2015 by imthebait

[GDJ]

WELL, I did it! Polar flight.

This is my submission for the Circumnavigator classification (1x around Kerbin).

RAPIER settings (no oxidizer, all jet fuel)

Take-off!

Glamour pic. She got a little warm in places, but nothing serious.

1/2 way around pic:

3/4 around Kerbin, south pole

Lining up for landing!

Landed, overshot the runway (brakes suck!) but she's on the ground in one piece! Flight data picture.

In case the screenshots didn't clearly show, the flight data:

Total Mission time: 1 hour, 8 minutes, 26 seconds (takeoff to landing)

Highest altitude achieved: 27, 704 metres

Highest speed over land: 1254 m/s

Dry weight: 8.5 tonnes

Loaded weight: 15.7 tonnes

Engines: Twin RAPIER

Craft file available upon request.

Edited May 19, 2015 by GDJ
Clarification

[GROOV3ST3R]

Trying to force a heavy VTOL carrying passengers to do a lap of Kerbin is like shooting yourself in the foot a day before a marathon.

It's heavy so it needs thrust to get it up to speed. Because of that, it drinks fuel like crazy at lower altitudes and has trouble climbing higher than 19km with any reliability.

Sitting too low wastes fuel and burns slowly heats up vital components. Sitting high deprives it of oxygen.

And all in the name of vanity.

Here is where I am at right now - a significant departure from the original format, that's for sure.

[Fengist]

I have finally finished the 3 lap challenge, the Eagle has landed and I can now say I never want to spend that much time watching my plane on fire ever again, while I'm pretty sure I could do 4 if I really put my mind to the challenge, cruising speed was 1200+, but altitude varied until I got done with the first circumnavigation, i had too much fuel to fly higher while still maintaining speeds above 1200,

http://i.imgur.com/tCUqQww.jpg

Eagle 1

Top speed: 1253m/s

Time elapsed: 2:44:53

Cruising altitude: 21000-22500m

Thanks all, I'm going to be monitoring this thread for really cool aircraft so i look forward to seeing other peoples submissions.

Fly Safe, oh wait this is KSP never mind, have fun!

While I don't doubt you bait... umm you got the images?

Well done to GDJ, our first polar explorer and a very nicely done to Phearlock for a double! You've both been added to the leaderboard.

At the moment, I have no plans to do far or allow any other mods that change the physics of the game or add parts and there's a reason.

The circumnavigation challenges, both Flix's and mine, have the new pilot in mind. I recall when I first started trying to fly aircraft, it took me days just to get one to the end of the runway without crashing. Flix's challenge was one of the first ones I completed, though I wasn't even trying at the time. His challenge spoke to me because I didn't need anything that KSP didn't provide. It was a 'level playing field' that I could participate in, even for me, a new pilot. For challenges designed for both old players experimenting with new designs and new players creating their first global capable aircraft, keeping that 'playing field' level is something I consider important. While stock physics may still be boring to you FAR pilots, there are gobs of challenges out there for FAR, NEAR and loads of other physics mods. And you're free to start one using FAR if you wish. This one, I'd like to keep it 'out of the box' simple.

Edited May 19, 2015 by Fengist

[GDJ]

Thank you Fengist!

I'm planning to do the challenge again, but this time fly retrograde against Kerbin's rotation, just to see the time difference if there is any. More of an experiment.

Theoretically, one's time should be far less due to less time in the air and Kerbin is actually rotating KSP towards you constantly.

Plus I burned up at least 15 seconds at take-off to turn north and a good 2 minutes at landing to turn, slow down and land.

Edited May 19, 2015 by GDJ

[imthebait]

While I don't doubt you bait... umm you got the images?

haha yeah, sorry i'll edit the original post and link em here

http://imgur.com/a/YWoyt

[GDJ]

Well, my experiment was enlightening.

I was faster by 15 seconds.

[DuoDex]

Hmm. Can you add a category for "Airliners"?

I was fooling around in the SPH and realized I had a double/triple possible circumnavigator with space for ~40 kerbals.

[Prof. Endwalker]

Doing this mission again. Using a better craft this time... And the air intakes exploded. Great.

[Fengist]

haha yeah, sorry i'll edit the original post and link em here

http://imgur.com/a/YWoyt

Our first Expedition Circumnavigator. Well done ITB... well done.

- - - Updated - - -

Hmm. Can you add a category for "Airliners"?

I was fooling around in the SPH and realized I had a double/triple possible circumnavigator with space for ~40 kerbals.

Well, there have already been a number of challenges to carry passengers around the planet. I'd rather keep this challenge pretty simple. Plus, the more categories I add, the more badges I'll have to create. I think 4 is quite enough.

[Squiggsy]

Half way through my challenge at the moment, will update this post when I finish, although I am in danger of running out of fuel before I make it (I am attempting it in the smallest craft I can, since I decided to dedicate today trying to complete as many challenges as possible in as small a craft as possible)

gotta say though seeing the sunrise after a long period of flying at night is such a nice feeling!

Edit:

SO ANNOYING

my game crashed I was so close, just going over the final bit of desert, was pretty sure I would have had almost exactly enough fuel to make it, I have reloaded the save but of course the F3 flight result doesn't show the correct distances any more, I have hundreds of screenshots of my journey around Kerbin though and the time still shows correct so can I use that or will I have to try again and spend less time looking at temperature gauges?

I'll await a response before spending the time uploading all the screenshots

Edited May 23, 2015 by Squiggsy

[Fengist]

I'll await a response before spending the time uploading all the screenshots

Just a few days ago, I had the same issue with another challenge. Rather than bring up questions of my times not matching, I set the challenge aside to try again later. The problem hosts of challenges have, if we make an exception for one, we have to make it for everyone. While I have no doubt you succeeded, without a valid F3 the 'burden of proof' no longer exists.

[Squiggsy]

Just a few days ago, I had the same issue with another challenge. Rather than bring up questions of my times not matching, I set the challenge aside to try again later. The problem hosts of challenges have, if we make an exception for one, we have to make it for everyone. While I have no doubt you succeeded, without a valid F3 the 'burden of proof' no longer exists.

yeah I assumed as much, ahhh well! was fun for the most part, I'll revisit it possibly tomorrow if I have the time, I reckon I can do it faster anyway thanks for the fast response

[imthebait]

Overhead, you hear a rising thunder, the sound of a sonic boom reaching you from above, looking up into the night sky you see nothing, no indication of an aircraft. Then, as you think you won't see it, a flare on the horizon catches your eye, the Maching Bird is in Flight!

i think this is approaching the speed limit on turbo's, unless i can get up around 25km while still traveling above 1300, i expect anything else may just burn up

I was wrong, very wrong, the minute i thought i would save turned into 4 and a craft capable of speeds that make rapiers worry, screaming across the sky at more than mach 4 is the

Maching Bird, http://imgur.com/a/uA0M9

Top Speed:1390m/s

Time: 49:28

The only way I think I could go faster is if I had the shock cones, but I'd be willing to bet its possible to cruise at 1400 m/s with turbos, but you have to bring the fuel for it.

Someone prove the need to have rapiers in the game, beat my turbos with superior power.

[juzeris]

Someone prove the need to have rapiers in the game, beat my turbos with superior power.

I'll bite . Since my first entry was just a bunch of parts crumpled together and tucked into a cargo bay, I figured I should do a proper circumnavigation anyway.

Thus, Abstract Aerodynamics present to you the newest member of its hypersonic sportsjet line - the Dartagor (download link).

This 13 ton beast sports a cozy cockpit certified for one Kerbal, a wingspan of 12.3 metres (perfect for any garage), an operating altitude of up to 30km (regulatory limit), sustained cruise speeds of up to 1640 m/s at 25km altitude and a bit higher top speed (we clocked it in at 1680 m/s) at lower altitudes for showing off, just don't keep the twinned powertrain running that hot for long. Our trademark engine housing also ensures a smooth experience by directing noise away from the cockpit and helps keep the engines below melting point in flight. While we won't say it is a simple construction, it is almost completely organic and contains only minimal part clipping. We also included a handy parachute for more convenient parking. Oh, and it also has global range, with full circumnavigation times as low as 41:44

To fly, the first tumbler switch toggles the engines, the third tumbler opens and closes the engine housing, and the tenth tumbler is for alternative parachute activation. As usual, we included extra tumblers for showing off, because nothing says 'pro' like flicking tumblers.

Javascript is disabled. View full album

EDIT: We also have an 'endurance' version of the Dartagor (download link), with significantly expanded fuel storage. Of course performance suffers slightly, the cruising speed is 10% lower, but Jeb just flew four times around the world in it in just 3:02:33. He even caught the whole event on his phone camera:

I messed up my settings, so the video ended up cropped, and, of course, both the fuel screen and the delta-v screen are cropped off. You can still see the vehicle mass decreasing in the vehicle window, which proves I'm indeed using fuel. There is also a heading control (MechJeb smart a.s.s.) screen open in the cropped off area, I kept it at a 1.2 degrees angle of attack for most of the trip. The F4 screen is also added:

Edited May 26, 2015 by juzeris

[MunGazer]

Cool stuff itb and juz, loved the reading. I've been extremely tied up with Assetto Corsa. You know, the whole turbojet vs rapier thing is kind of seeming to me like it's turning into a Ford vs Chevy thing haha. Juz, I've looked at some of your other stuff and just the sheer handle you have on these data tools is amazing. One of the reasons I've only messed with stock is I haven't committed to learning those tools yet. The more I think about doing an in - depth analysis of what the optimum application specific ascent profile would be, the more I begin to think those tools will make the process much more painless. It could be sort of a compromise between the Ricky Bobby testing method and getting a math degree. Even when optimally piloted, I'm certain my craft won't approach an average speed anywhere close to 1,573 m/s during a circumnav. At this point, I'm interested not only in finding the best ascent and descent profiles in this context, but also an objective and thorough comparative analysis of rapier and turbojet engines. The question remains... given the "most expertly designed craft and usage" for either engine, which of those two dream craft would perform better in this application? What about a hybrid? Thus far, I'd lean toward the rapiers having the upper hand, but I still have a healthy respect for turbojet potential and haven't viewed it as being inferior before. I just didn't look hard enough for a good turbojet set up.

Edited May 27, 2015 by MunGazer

[juzeris]

Well, to be fair, the turbojet was strictly better than the rapier before 1.0. Things change, however, and since it is actually not a very hard question, let's try to answer which is better and when. Starting from the simpler aspects:

• The Turbojet (1.8t) is slightly lighter than the Rapier (2.0t), but the difference is not very significant for atmospheric vessels, where drag dominates the speed equation and not mass. It might become more significant for a Nerva powered SSTO where the Rapier rocket mode is not used, not sure.
  
• The Turbojet has an alternator (it generates electricity), while the Rapier does not.
  
• The Rapier has a back stack mounting point, while the Turbojet does not. The uses are limited to shenanigans, because otherwise it would block the engine, but, personally, I often end up using it.
  
• The Rapier seems to generate slightly less drag (1.299081 0.9353406) than the Turbojet (1.275294 0.9736242), I haven't tested this though, the data comes from this post.
  
• The Turbojet has a better fuel efficiency (Isp 8000) than the Rapier (Isp 6400) for a given thrust level. I calculate that as using 80% of the fuel a Rapier would use. Both jets are still very fuel efficient however. (Credit to Red Iron Crown for correcting this )
  
• The Turbojet uses a higher proportion of air to fuel (15:1 vs 12:1), this may or may not mean more intakes producing more drag for a given level of thrust, depending on your design.
  
• I cannot really comment with any authority on the thermodynamics of the engines, the parameters seem fairly similar and they both appear to produce a similar level of heat for a given thrust level.
  
• And, of course, most importantly, engine power - it is calculated as thrust*velocity coefficient*atmospheric coefficient, where thrust for the Turbojet is 180 and 140 for the Rapier. Of course, the coefficients are the interesting part. These are saved as curves in the .cfg files in your KSP directory, but for simplicity I've rendered them into graphs below.
  

Let's start with the atmospheric coefficient. The graph below shows the relation between the coefficient and atmospheric pressure. The relation is logarithmic, however I could not figure out how to make my graph logarithmic, so apologies. According to the wiki converting between pressure and altitude is not as straightforward as it used to be, but it includes a handy table. From the graph we see the Turbojet has a better coefficient up until about 0.08, which, based on the table, is somewhere a bit below 15km altitude, and the Rapier stays significantly above the Turbojet the rest of the way.

Turbojet is red, Rapier is green.

Next up, the velocity coefficient. I've scaled the graph to adjust for the Turbojet's higher thrust, it's easier to look at that way. The speed is in Mach, and I believe the conversion to m/s varies with altitude, but a general assumption of about 300m/s per Mach at 20-25km should hold. Here we see the Rapier overtakes the Turbojet at somewhere a bit below Mach 2.

Turbojet is... grey? Rapier is green.

Conclusion/tl;dr: The Rapier appears to be strictly better in terms of performance when flying above 15km and over 600m/s, which should be most of the cases when you actually care about the engine type.

The turbojet has the benefit of being more fuel efficient, but you'll probably make up for the efficiency to some extent by going higher and faster where you need less thrust and the journey is shorter (by time).

Please let me know if I got something wrong somewhere.

Sources and tools: game files, the KSP curve tool by MuMech, Gimp, and a calculator. You can find some intermediate graphs here, if you want them for some reason.

Edited May 30, 2015 by juzeris
Corrected efficiency (thanks Red Iron Crown!)

[MunGazer]

Excellent information there Juzeris, thanks. I'm sure many people will find it helpful, including myself, having all that information relevant to engineering the highest speed and altitude aircraft compiled into one place. I think one of the most important things you mentioned for me or for anyone to keep in mind is that drag dominates the speed equation more than mass in this context. Of course, there are several ways to do a circumnav and not everyone is trying to be the fastest, but for those that want to have lots of nifty extra features on their craft and be the fastest at the same time, or set a lofty air speed goal, one may have a lot of difficulty having his cake and eating it too, at least at some point anyway. Interestingly, when adding mass, that will at some point require more lift, which in turn will create more drag, etc. The cold, hard numbers are right there in the config and we can't design our own jet engines. Whoa.... how cool would that be? . How about it, squad? Balancing system, jet lab, make your own engines?