The Kerbodyne Loop & Land Sprint

[Wanderfound]

This is a pure piloting challenge, which should also work as a good aerobatics and landing trainer. To do it, you'll need the basic FAR jet shown below. The craft file is at https://www.dropbox.com/s/eqo5b7v5ef89g8s/Kerbotrainer.craft?dl=0 for the FAR/NEAR plane, and https://www.dropbox.com/s/su6ummix7jg389v/Kerbotrainer%20Stock.craft?dl=0 for a stock aero version.

It's very quick and simple: just take off from KSC, fly out over the beach far enough to get a crew report over water (not "shores"), then turn around however you like and land back on the runway at KSC. Fastest time wins; post screenshots of your crew report and your ship stationary on the runway with elapsed time visible, plus whatever other images you feel like.

The plane is set up with the following action groups:

1: Turbojet

2: Fuselage intake

3: Structural intakes

0: Crew report

It's built for FAR, and I have no idea if it will even fly in stock, but if anyone wants to try it in the soon-to-be-extinct soupmosphere, they're welcome to try (edit: stock aero version now added).

Piloting data and visualisation aids (e.g. Kerbal Flight Indicators) are fine, full autopilots (e.g. Mechjeb or Kerbal Pilot Assistant in autopilot modes) are not. Using Kerbal Pilot Assistant just as a PID tuner is fine. No other non-cosmetic mods allowed; no time slowing, gravity hacks, etc. etc. If you're not sure about a mod, ask.

Take off at whatever speed you like. Don't bother trying to spool the engines up; the turbojet will overpower the wheel brakes almost immediately.

You may wish to cut throttle fairly early; however, it's up to you.

Crew report (action group 0) over water. Make sure that you're far enough out for the biome to change; "shores" continues for a fair distance.

Horizontal loop or Immelmann, conventional or inverted; your choice.

Spinny spinny.

And back down. Dropping like a rock.

But leveled out easy enough. The plane can take substantial G's, although it is possible to break it if you try very hard.

The plane has adequate brakes, but not excessive, so you want to get onto the runway as early as possible.

Ta-da! 2 minutes 10 seconds.

With room to spare.

Leaderboard

Stock Aero

Zarakon, 1:11

Merandix 1:31

FAR/NEAR

Wanderfound 2:09

Edited January 21, 2015 by Wanderfound

[Vanamonde]

Objectionable post removed, and some posts quoting and replying to it removed. Just play the challenge or not, folks. No need to get nasty about it.

[Hodo]

Does it have to be that craft or can I make my own simple aircraft or use my own?

[Sigma118]

I downloaded the craft but it won't even take off, just keeps bashing against the runway.

[Wanderfound]

Does it have to be that craft or can I make my own simple aircraft or use my own?

Post a go with your own if you'd like, but for comparable results you'd need identical aircraft. And it's a bit too easy to build some ultra-micro overpowered thing that can just flip on its tail and rocket back the other direction, so I didn't think it would be too interesting as a design challenge.

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I downloaded the craft but it won't even take off, just keeps bashing against the runway.

Are you flying in stock or FAR?

As you can see here:

...it should take off with minimal effort at around 120m/s. You do need to let it get up to that speed before pulling the stick back, though; the drag from the stalling tailplane will interfere with your takeoff run if you don't.

However, that is in FAR; if you're flying in stock, the absence of the FAR mass tweakable is going to substantially unbalance it, and as stated above it may not work at all. If that's the case, if a stock flyer wants to throw together a stock equivalent test plane, they'd be welcome to do so.

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Okay: just to make sure that there wasn't any problem with the plane, I did another run, this time with more detailed coverage of the takeoff process: http://s1378.photobucket.com/user/craigmotbey/Kerbal/Challenges/Loop%20and%20Land/Second/story

Still flying fine, as far as I can see.

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I just set up a stock aero install to test, and as suspected, the FAR plane has problems in stock. CoL too far back and control surfaces set to influence all axes, allowing the wings to negate the elevators. Almost unflyable in stock air.

So I built a stock aero version.

Takes off easy:

No trouble with the necessary aerobatics:

See https://www.dropbox.com/s/su6ummix7jg389v/Kerbotrainer%20Stock.craft?dl=0 for the craft file.

Edited January 19, 2015 by Wanderfound

[Merandix]

Ok, this can be done waaaay better... but I basically have insufficient hands. This is also the reason why I do NOT have any screenshots other than pre take-off and post landing. I do have the report to prove that I've been over the water, but I'm really unable to make a nice screenshot of the actual aerobatics, as the moment I make that crew report, I kind of have my left hand over the 0 button on the keyboard, then I need it for my flight controls, because THAT INSTANT I have to turn around. Which is a fairly involved manoeuvre when it comes to my left hand. I also cannot spam the crew report with the mouse nor can I dismiss a crew report with the keyboard, so I need both hands for the crew report. Likely this time would be faster if the craft had the crew report mapped to 2 or three, so my left hand can reach that button without leaving the flight controls.

To describe what I'm doing, I basically use an Aerobatic Immelmann turn (half loop + half roll at the top) from an altitude of about 100-200 meters, and as tight as possible to turn around, then land, trying to find a balance between as much and as little speed as I can manage (more speed means I'll be at the runway quicker, but take longer to stop, less speed means I'll stop faster, but reach the runway slower).

Final time: 1:31

edit: in stock that is

Javascript is disabled. View full album

Edited January 19, 2015 by Merandix

[KerBlam]

HAHAHAHA no no noooooo nope!

I can't slow this thing down enough to land on the runway, even at a dead stall and gliding it in, I'm still around 150m/s... endless fiery deaths. What a fidgety little plane!

I need more practise.

Edited January 19, 2015 by KerBlam

[Wanderfound]

HAHAHAHA no no noooooo nope!

I can't slow this thing down enough to land on the runway, even at a dead stall and gliding it in, I'm still around 150m/s... endless fiery deaths. What a fidgety little plane!

I need more practise.

BTW: are you using a PID tuner? If not, highly recommended; there's one included in the Kerbal Pilot Assistant mod. Takes all of the wobble out of SAS.

[KerBlam]

What's the PID acronym stand for? I'll check it out..

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What's the PID acronym stand for? I'll check it out.. Do you have a link? I can't seem to find this.

[Wanderfound]

What's the PID acronym stand for? I'll check it out..

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What's the PID acronym stand for? I'll check it out.. Do you have a link? I can't seem to find this.

Complicated explanation: http://en.wikipedia.org/wiki/PID_controller

Simple explanation:

Stock SAS is horrid for spaceplanes. It's designed for rockets and stock aero, and it reacts badly to vehicles with a lot of control authority (e.g. spaceplanes). This leads it to continuously overcorrect, resulting in pitch and yaw wobbles of increasing severity.

The best solution is to get a mod that includes a PID tuner, and use that to reduce the sensitivity of the SAS. For a good PID tuner, see http://forum.kerbalspaceprogram.com/...-piloting-aids Go into SAS setup, change it to Stock SAS mode, then get into the PID tuner settings.

Exactly which PID settings are best depends upon craft and preference, but a good starting place is to cut all the kp values to 1/3 of default, and reduce the scalars to 1/2 default.

[KerBlam]

Thanks, and that works for FAR as well? I'm not sure, SAS is the same in FAR as stock?

edit: NM some comments in thread confirm this works with FAR

Edited January 20, 2015 by KerBlam

[zarakon]

Stock, 1:11

[KerBlam]

Nice one... My wings would tear off if I tried that turn at full thrust.

[Wanderfound]

The first horizontal attempt; nicely done.

[zarakon]

You may want to preemptively add a rule against rolling down to the end of the runway pre-launch. You can save quite a bit of time in this one (and to a lesser extent the Touch & Go challenge) by rolling down to the east end without the timer starting.

[Merandix]

Wait... we're allowed to spool up our engines BEFORE the timer starts? That alone saves a few seconds probably!

Also, how in the world to you get that marker out there? I waste at least a few hundred meters trying to get that crew report.

edit: confirmed that just flying a circle is faster... Though that makes me wonder about the 'loop and land' bit. Though technically, it's just a horizontal loop obviously.

Anyway, awesome record. I can't reproduce it with my amateur flying

Edited January 22, 2015 by Merandix

[zarakon]

The marker is just a capsule that I put out there and renamed

And yeah, the trick with the engine is:

- shut all your intakes

- hold the brakes

- turn on the engine

- wait for flameout

- throttle to max

- wait a few seconds

- re-open intakes and the engine should kick in immediately at full thrust

[Wanderfound]

You may want to preemptively add a rule against rolling down to the end of the runway pre-launch. You can save quite a bit of time in this one (and to a lesser extent the Touch & Go challenge) by rolling down to the east end without the timer starting.

I'd assume that would be covered under Wheaton's Law, but to clarify just in case: folks, no sneaking down the runway. If you're not sure if something is legit, ask.

[Merandix]

Yeah, I figured out the trick based on the flameout.

I did another attempt... a sloppy landing led to the amazing time of... *drumroll* 1:31... <.<

Which is fairly amazing since I managed to put down the exact same flight time with different flight plans...