The "Coming in Hot!" Landing Challenge

[Yakky]

Updates: Some really good recent entries from Chengong and Goduranus have claimed the top spots!

Put your re-entry and landing skills to the test! This challenge is to design and land a glider-style vehicle from Kerbin orbit without using parachutes or rocket-assisted touchdown, using as few wings and control surfaces as possible. In other words, design a stubby-winged flying paperweight that can just barely glide in for a safe landing. The fewer wings, the higher your score!

NOTE: FAR (Ferram Aerospace Research mod) aerodynamics are encouraged, but not required, for this challenge.

Motivation: NASA experimented with "lifting bodies" in the 1960's and '70's as a compromise between a ballistic, capsule-style re-entry vehicle and a winged, Space Shuttle-style vehicle. The idea was to come up with a flying capsule that was just barely controllable enough to allow for a runway landing but without the design challenges of building large wings and control surfaces that would be prone to burning up and disintegrating during re-entry. Check out the "lifting body" article on Wikipedia for more background.

Scoring: Note: Stock speed bonus has been updated!

Your total score is your Base Score times any bonus multipliers you earn.

Base Score: Your base score will be (mass)/(lift), where mass is the mass of the vehicle at landing and lift is the sum total lift of all the lifting surfaces on the vehicle.

Bonus Multipliers: There will be a 2x skill multiplier for landing on the flat plain around KSC and a 5x skill multiplier for landing and stopping completely on the KSC runway (you only get one or the other, not both). In addition, there will be a 2x skill multiplier if your touchdown speed is over 250 m/s in FAR or over 150 m/s in stock.

Note: I expect all the entries will probably have some wings. But in the event anyone succeeds in landing a rules-compliant craft with no wing surfaces at all (i.e. infinite score), relative ranking for infinite scores will be based on (mass)*(bonus multipliers), ahead of all the finite scores. BTW I would totally love to see this!

The Fine Print:

1. Start from Kerbin orbit. No power is allowed after you re-enter the atmosphere, and your re-entry speed at 70 km must be at least 2000 m/s (in the Orbit reference frame). No fuel use allowed below 70km or 2000 m/s.

2. Stock only, except that FAR is highly encouraged for realism. There will be separate FAR and non-FAR divisions. Mods that don't affect parts or physics, like Kerbal Engineer and Kerbal Alarm Clock, are OK. Kerbal Engineer is encouraged to show ship mass.

3. No MechJeb. Part of the challenge is to pilot it yourself! (Plus I suspect that MechJeb would not be able to fly the highly optimized trajectories that the best entries will undoubtedly need.)

4. No parachutes and no destructive lithobraking. The entire craft that re-enters the atmosphere must land intact in one piece. Do all your fuel burning, jettisoning, staging, etc before you re-enter the atmosphere (i.e. above 70 km).

5. Using sneaky tactics to circumvent the intended spirit of the challenge is discouraged. In particular, to discourage the abuse of the wide and flat structural panels as de facto wings, the M-1 and M-2 structural panels will each be assigned a lift value of 2.0 for scoring purposes. (This matters in FAR.) Flagrant abuse of other wide, flat parts may result in lift values being assigned.

6. No abuses of unrealistic physics. This means no significant part clipping, no spamming massless parts, no infiniglides, no Kerbal ladder drives, no kraken drives, etc. As a rule of thumb for part clipping, no part should be more than 5-10% clipped, if even that much.

7. Documentation: Post screenshots, movies, or other info clearly showing your ship design; your velocity, fuel, and mass at 70km; your velocity, fuel, and mass shortly before touchdown; your velocity, fuel, and mass shortly after touchdown; and your position, fuel, and mass at full stop. Also clearly document the total lift of your vehicle. Additional screen caps and narration detailing your adventure are of course encouraged!

8. The craft must have some kind of kerbal capsule or active probe core on it. This isn't a competition to find the most robust part and drop it onto the runway from orbit. As of September 17th, asteroids are specifically disallowed although Goduranus submitted an asteroid-drop entry before this date, which will be grandfathered into the standings.

Standings:

FAR Division:

1. Goduranus. Infinite score with 78,400 tiebreaker points for landing a 15,680 kg craft with no wings on the KSP runway for 5x skill bonus. Well done! http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1423064&viewfull=1#post1423064

2. Chengong. 1,053,187.5 points for landing an 84,255 kg craft with 0.4 lift on the KSP runway for 5x skill bonus. http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1424205&viewfull=1#post1424205

3. Chengong. Scored 92,187.5 for landing a 14,750 kg craft with 0.8 wing area on the KSP runway for 5x skill bonus. Nice! http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1422911&viewfull=1#post1422911

4. Yakky Scored 10062 for landing near KSC. See http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1420612&viewfull=1#post1420612

5. Yakky. Scored 5906 for landing near KSC. See http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1400693&viewfull=1#post1400693

6. SkyRender. Craft was obliterated by high aerodynamic forces, but somehow the cockpit and crew survived. Score: zero (awarded tiebreaker for 5th place because he somehow didn't kill his crew despite the obliteration of his spacecraft). http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1399356&viewfull=1#post1399356

Non-FAR Division:

1. Goduranus: Infinite score* due to the intact landing of an 845-ton asteroid with capsule attached, with no wings. *Note that because asteroid drops are questionable under Rules 5 (no sneaky tactics), 6 (abuse of unrealistic physics), and 8 (not a competition to drop most robust part from orbit), I am removing asteroids from the list of allowed parts for all future entries, and I will deprecate Goduranus' score in favor of future entries that fully adhere to the spirit of all rules. But Goduranus will retain at least an honorable mention for pioneering an interesting concept. Entry post here: http://forum.kerbalspaceprogram.com/threads/92729-The-Coming-in-Hot%21-Landing-Challenge?p=1421090&viewfull=1#post1421090

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Most Awesome "Coming In Hot" Subjective Awards (presented at judge's discretion for most impressive/unusual hot landing videos or concepts, regardless of success or failure):

1. Goduranus: for landing an asteroid that cushioned the attached space capsule from destruction. Interesting concept, worth an honorable mention at least, but not really in the spirit of the competition. (See above.)

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5.

Edited September 18, 2014 by Yakky
Added Chengong's million-point run!

[cyberklad]

You need FAR or NEAR to do this. Stock aerodynamics does not support lifting body designs.

[cantab]

You can still make gliders in stock aero, and you can make something that looks like a lifting body, or anything else.

Regardless, the challenge doesn't actually constrain ship appearance. I could make an entry that looked like a U-2 if I wanted, though it probably wouldn't score very high.

[Yakky]

That's right -- it doesn't have to be a lifting body. Any type of gliding plane will score points, but the challenge is to see how few wings you can get away with.

BTW one of the harder aspects of this with FAR appears to be not having the wings rip off under high load. That's already happened to me a couple times on my test vehicles. Most likely the winning designs will be a combo of careful design, moar strutz, and careful flying that doesn't overstress the airframe.

Edited September 3, 2014 by Yakky

[Kasuha]

There's no way to have 250 m/s horizontal speed at touchdown with stock aerodynamics.

[Yakky]

Yeah, probably not with stock. I only play FAR these days but I remember stock aero being much more soupy.

I would consider a lower threshold for being awarded bonus points under non-FAR aerodynamics, but I would still want it to be very fast and somewhat hard to achieve, i.e. requiring a very steep dive with a pullout at the last possible moment. What's a good speed threshold for non-FAR? 150 m/s? Any thoughts?

Edited September 3, 2014 by Yakky

[SelectHalfling0]

EDIT: To hard in stock. I tried using the 999m/s impact tolerance of a stuctural pylon, but only the pylon survived!

Edited September 3, 2014 by SelectHalfling0

[battlefieldaces]

IMO Structural panels or such flat parts should not be assigned lift if they're not used as wings

[Kokanee]

OP can you do the challenge in stock to prove it's possible?

[Wanderfound]

Will you allow the use of NRAP to let people crank up the weight without having to inflate bulk and part count?

I can probably get a fuselage plus a couple of AV-R8's down intact with more than their own weight, but trying to beef up the mass to the limit with stock parts would require strapping on several times its own size worth of SRB-KD25k's or something. There aren't really any high-density small stock parts.

It's not a realism-breaker; even at its 100t maximum (unlikely to succeed), NRAP is no more dense than a lump of solid metal ballast. The tweakability of it would also allow people to really push the limits of their builds, which is always good for dramatic screenshots.

Just don't let 'em get away with using it as landing gear; NRAPs are indestructible.

I'd suggest making the horizontal speed bonus competitive, BTW; instead of giving it to everyone who exceeds a set landing speed, have a couple of bonus point awards for 1st/2nd/3rd fastest etc. That'd solve the problem of being unsure of where to set the thresholds.

Anyone having fun with this is welcome to have a shot at the powered piloting equivalent, BTW: http://forum.kerbalspaceprogram.com/threads/91511-Spaceplane-Speed-Challenge-2-Fastest-time-from-orbit-to-runway

[Yakky]

One idea I had was to do a formula-based bonus for speed. E.g. your landing speed bonus multiplier is something like (actual landing speed)/(150 m/s) for any speed over 150. What do you think?

I didn't initially do that because I thought it was too complicated. But I will listen to the thoughts of the community on this one...

Edited September 3, 2014 by Yakky

[Yakky]

Wanderfound: I understand the desire to crank up the density via test weights, but I'd like to keep it to stock for the main points-scoring part of the challenge. But please feel free to submit non-stock test weight craft for the judge's discretion video awards. I'd love to see a video of an impressive landing with a super dense craft.

Just as with big launches, part of the challenge with landing a big craft is keeping it all together and finding a part configuration that works.

Kokanee: Any unpowered aircraft landing from orbit would meet the requirements, so I'm sure it's possible in stock. The big question is how far people can push the limits of minimal wings... that's the challenge.

Battlefieldaces: It's mostly a FAR issue since stock aero doesn't care so much about configuration. Are you planning a stock entry? Send me a pic of what you have in mind and if it's reasonable (e.g. isn't sticking out in the breeze too much), I will consider a waiver.

[Yakky]

BTW -- Wanderfound, what I would suggest is to use the NRAP ballast parts for testing and development (and of course pilot training!). And by all means post pics or movies of your progress... I'm sure they will be inspiring and entertaining. Then when you have something workable, see if you can find a way to translate your knowledge/skills into something built out of stock parts, e.g. a modified design build around a cluster of full Rockomax 64 orange tanks or something.

[Yakky]

EDIT: To hard in stock. I tried using the 999m/s impact tolerance of a stuctural pylon, but only the pylon survived!

You need to use a few wings. Wings are allowed... The score just gets better the fewer you use. Hopefully I will get around to posting an example this weekend.

[r_rolo1]

Hum, can you actually get reliably a unpowered but controlled 150m/s aproach to anything in Kerbin sea level in stock? Terminal velocity in there is normally around 130m/s, so you need to come really hot to get above that, given the well known features of current stock atmo...

Case in point: this . For full effect start at around 1:30 :/

Edited September 6, 2014 by r_rolo1
Forgot the "in stock" part. It is important for the post :D

[dbmorpher]

I'll try this once I get my Duna Mission on its way.

I think the scoring should be Mass(Speed/Wing #)

[Yakky]

Hum, can you actually get reliably a unpowered but controlled 150m/s aproach to anything in Kerbin sea level in stock? Terminal velocity in there is normally around 130m/s, so you need to come really hot to get above that, given the well known features of current stock atmo...

Case in point: this . For full effect start at around 1:30 :/

That video was pretty awesome. He was doing about 250 m/s when he finally buzzed the treetop. Based on that footage, I would say that exceeding 150 in stock aero at touchdown is plausible with the right craft and the right trajectory. It might possibly require starting from a much higher speed than normal LKO speeds though.

But this footage also shows that for stock aero, the 2x bonus for 250+ m/s touchdowns clearly needs to be recalibrated... hence I will lower it to 150 for stock.

(Interestingly, the video doesn't completely rule out the possibility of a 250 m/s touchdown with stock aero... but pulling one off would be about like scoring an 18 in golf. Not technically impossible not also not likely to ever happen in our lifetimes.) :-)

Edited September 6, 2014 by Yakky

[r_rolo1]

Hence my point on reliability Notice that he was at 10 km/s when he entered in the atmo and he was going in a almost vertical dive ( more, stock atmo does glitch a little in those high speeds, giving less drag than it was suposed to ( in brief terms, the calcs for drag update are done in fixed intervals ... if you are going too fast, the updatesto the drag start to be too spaced out for the situation ... ) ) and , in spite of that, he got to 250 m/s at slightly above sea level. My point was not that it was not possible, but how hard it will be to get a unpowered 150m/s horizontal touchdown in stock ...

Edited September 6, 2014 by r_rolo1

[cantab]

Ironically for this challenge (and reality), I think the way to get a fast touchdown might be to have a ship that's mostly wings, since they have a high mass-to-drag ratio. Especially if you were to say spam tailfins that won't create any lift in straight flight.

For example I knocked up a ship that was basically 24 winglets around a probe core and gave it a suborbital lob. It was accelerating throughout the re-entry effects, and hit the ocean (and actually went through) at around 1700 m/s.

[Yakky]

That's interesting. It kind of makes sense because the weird aerodynamics of stock KSP make wings much "faster" due to their low drag coefficient (0.02 vs. 0.2 for most parts, if I recall correctly).

[Yakky]

OK, so here's my sadly comic illustrative example of what I have in mind for this challenge. Never mind that this design failed when the (ahem) wings ripped off and the poor Kerbal crew lithobraked into oblivion... but at least I tried. Hopefully posting it will encourage more of the same. I mean ideally, not with all the, you know, Kerbal deaths and stuff.

BTW this was just a quick and dirty test design to give readers some idea for what to build for this challenge. It's pretty basic, just a large orange tank with a standard 3-seater cockpit, a nosecone, some landing gear, and tiny little stubby wings and tail surfaces. It took be about 20 seconds to design and build. To wit...

Here we are after launch, coasting through space on a sub-orbital trajectory. I just launched the whole thing vertically, and for purposes of this test run, I didn't even go all the way to a true orbit, just up to over 70 km and over 2000 m/s as per the rules. Could have easily done orbit-- plenty of fuel-- but I was too impatient to run the test. You can see how basic this design is.

Here we are coming in hot. The dynamic pressure (Q) on the airframe is up over 100k at this point, but things are holding together so far.

I'm trying to keep the pitch up to avoid plummeting down into the thicker atmosphere too soon, since I know from past experience the wings will rip off if I get down there with too much speed. Here I am around 14 km with actually a slightly positive climb rate, as indicated by the vertical speed indicator at the top center. Still hauling ass though. Notice that the dynamic pressure (Q) has come down to 89k, which is trending in the right direction. And the positive climb rate has proven that she glides, sort of. If I can get the sink rate down to 0 here, I should be able to do so near the ground and maybe actually land this thing.

Slowing down even more, and keeping the dynamic pressure from getting too ridiculous. But upon closer inspection, the seeds of disaster are looming. My sink rate has gotten dangerously high. This will have, um, troubling consequences in a moment or two.

Whoops, where have the wings gone? I guess I overstressed the airframe a bit too much trying to pull up a bit. This is probably not going to end well. But even though now I'm technically disqualified since parts have come off my aircraft, I'll still try to land this baby and save poor hapless Jermin, Anford, and Newfal.

Uh-oh. Despite full nose-up pitch (note the elevator deflection), we are not able to really pull the nose up. Um.... a pair of wings would really help right about now.

Gear down for "landing". Brace yourselves, boys. Coming in at a 20 degree down-angle trajectory at 424 m/s means your vertical speed is almost 150 m/sec. And unfortunately the ground is pretty lumpy here to boot.

Yeah, there it is... a failure on so many levels. But hey, at 395 m/s at least I would have gotten the speed bonus!

[SkyRender]

This looks like it could be interesting. I threw this together to see what would happen:

Don't be fooled by its spaceplane-like appearance; that thing has about as much lift as a paper airplane with a paperwieght glued to it. It had to take off vertically to even reach orbit and couldn't really pitch up at all below 15KM lest it cause aerodynamic failure, that's how little lift it has. I suppose I'll have to try to land it next...

[SkyRender]

You know the saying "any landing you can walk away from is a good one"?

I think this qualifies that statement nicely... The landing sequence went about how you'd expect for a craft like that: flaps ripped off, then the wings, then the engines. It hit the ground going 84.2m/s and amazingly did not destroy anything save the front landing gear on the forward pod. The cargo bay off in the distance there decided to spin around for almost a minute upon impact.

[Yakky]

Nice. Well, you kept your Kerbal pilots alive, which is more than I can say for my effort. That's worth something even though your craft was obliterated. First place, for now, with a score of zero points.

[Yakky]

Another attempt with bigger wings. This one just barely failed... I cannot seem to stick the landing! :-( In the final analysis, doing well at this challenge is really about the piloting. You have to fly a hard-to-control craft through a very delicate envelope to keep it from disintegrating, then use what little control you have to grease it in for a perfect landing. Not easy to do!

On the pad:

About to re-enter the atmosphere:

Peak heating as we head toward KSC. I used the blunt crew capsule to make it as un-aerodynamic as possible to help slow down quickly.

Surprisingly well lined up, but...

... I can't stick any of the landing attempts! Need to work on my piloting skills, I guess. :-(

Edited September 7, 2014 by Yakky