The "Coming in Hot!" Landing Challenge

[Yakky]

OK, after several dozen saves/restores, I've finally done it! After moving the landing gear around slightly and abandoning my efforts to put down on the runway, I've successfully landed a craft from orbit and gotten a nonzero score! (Sorry for all the over-exuberant exclamation points... but I've been working at this for so long that I feel the need to celebrate.)

Mass at touchdown: 14,765 kg (9,860 kg empty + 2205 kg fuel remaining + 2700 kg oxidizer remaining)

Total lift from wings: 5.0 (1.9 x 2 main wings + 0.4 x 3 tail fins)

Base Score = 14,765/5 = 2953

Plus I landed on the flat plain near KSC, so I get the 2x bonus.

Total score = 2953 * 2 = 5906

Some highlight pics:

Just before atmospheric re-entry:

Heading to KSC (again):

A very careful landing flare. Notice my speed isn't really that "hot" anymore. (Surely someone can do better?)

Stopped! And nobody died!

Now... can someone with more talents than I please do better?

Edited September 7, 2014 by Yakky

[Yakky]

I was able to get a higher score by landing an even heavier craft with the same wings as above (due to significantly more fuel remaining). I strapped on some boosters at launch that allowed me to reach orbit with half an orange tank remaining. Mass at re-entry and landing was over 25 tons, landed unpowered on just a basic pair of delta wings and three basic tail fins!

Successfully performing an unpowered gliding landing from orbit with a half-full orange tank and only two tiny wings in FAR was a massive but ultimately very satisfying challenge. Took me about 200 attempts and almost 50 quicksaves. Even with the reinforcing struts I added, there was only a wafer-thin margin between ripping the wings off from maneuvering too aggressively and barreling into the ground like a rock. I didn't document touchdown speed but it was around 150 m/s (I was too busy with the controls). This was a very heavy craft (for the wings) and really got at the spirit of what I intended for this challenge.

Score:

Total landed mass: 25,155 kg (9860 kg empty + 6885 kg fuel remaining + 8410 kg oxidizer remaining)

Lift: 5.0 (same as above)

Base Score = 25,155 / 5 = 5031

Multiplier: 2x for landing near KSC

Total Score: 5031 * 2 = 10062

If you're a good flier and up for an interesting challenge, I'd really love to see someone else put up an impressive stubby-winged heavy landing here or at least document an attempt. If you do try it, my advice is to quicksave early and often! :-)

Just before re-entry, with the orange tank nearly half-full:

Trying, trying, trying to line it up right for a runway landing. (This very heavy glider flies like a pig and I never was able to get it, so eventually I gave up and landed off to the side.)

Finally landed and stopped next to the runway!

Edited September 17, 2014 by Yakky

[Bilfr3d]

There is no limit for weight, or fuel, etc, is there? And do the pylons count as aerodynamic parts? Either way, I will be sure to give this challenge a crack with FAR.

[goduranus]

So all stock parts are allowed(even kraken drive) as long as you dump it before you hit atmosphere? I will try this challenge when I get home.

How about going in with a ballistic capsule with no wings but use high-tolerance pieces to absorb the impact?

Edited September 17, 2014 by goduranus

[Bilfr3d]

Newsflash - I suck at challenges. I used hyperedit to get a feel for how fast I could potentially get my ship back into kerbin... from a 12000000km Ap orbit... I reentered at 5000m/s plus. As expected, the pod - along with every single other part on the ship; including the struts - broke off and hurtled towards the ground at blistering speed. Jeb, Bill and Bob got splattered over the ground at 1000m/s plus.

[goduranus]

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!

Here's my no-wing submission. Basically "found most robust part and dropped from orbit" approach. But hey, it has a capsule! So conforms with the rules.

Craft is made up of a capsule, a claw and an asteroid

Score:845 tons(no wings)

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Edited September 17, 2014 by goduranus

[Yakky]

@Goduranus: Not quite what I had in mind, but (for now) you are at the top of the stock aero leaderboard because nobody else has submitted an attempt in stock aero. Kudos for thinking outside the box both in terms of weight and indestructibility. But as I'm sure you realize, the concept is to produce something that can actually engage in some form of controlled flight, rather than finding the most crater-resistant part and dropping it from space, so I might move you down the standings if other people come up with designs more in the spirit of the challenge. Thanks in any case for submitting an entertaining entry!

BTW I am going to revise the rules to eliminate further attempts with asteroids... you have proven the asteroid concept and I don't think there's much point in having more people compete to find the largest asteroid they can land. I'll keep you grandfathered in since your entry wasn't technically illegal at the time you entered it.

@ToTheMun: No weight limit. Heavier weight with smaller wings will produce a higher score.

Edited September 17, 2014 by Yakky

[Yakky]

@ToTheMun: Thanks for at least trying. A very high re-entry speed is not necessarily the best approach here. I would suggest going for the lowest possible re-entry speed (above the required 2000 m/s, that is) so that you don't have so much kinetic energy to dissipate. Also, try coming in at a very shallow angle and bleeding off as much speed as you can at the highest possible altitude. For my successful entries, I basically held them pitched up at a very high angle of attack to arrest their descent into the lower atmosphere until they slowed down a lot. Otherwise the atmospheric forces shred them.

[Bilfr3d]

@Yakky, its a good challenge and is the first one I have properly attempted. I am going to give it another go today to try and land a real heavy ship. I re-entered so fast because I wanted to try and land above 250m/s to get the FAR speed bonus. I had an idea to chuck some panels at the back of the craft and make them angled so they could sap some speed. The only problem I think I am going to have with that is the panels ripping off, so I'll need to watch the stress on the way down. Big NASA tanks, here I come!!

[goduranus]

I would rather think that the way to win this challenge is to use parts that have the lowest mass to surface area ratio, and connect them side by side so the aerodynamic forces on most of your ship's major components are the same, so nothing rips off. Basically a wing made out of fuel tanks.

I imagine about five empty FL-400 tanks arranged side by side, each with two advanced reaction wheels for steering and a landing gear front and back, then a nosecone in front. Plus plenty of struts for structural integrity.

You launch this thing a rocket in the back of each tank, then detach the rockets to save weight before you enter atmo.

I don't have FAR, but can someone try this out?

[Bilfr3d]

Rather than a nosecone on the ship, put one of the big flat panels with lost of struts attached to it. That'll slow you down faster. The tank wings sound like a good idea. But have the tanks FULL!! After all, you get more points by having a heavier kit.

[goduranus]

But have the tanks FULL!! After all, you get more points by having a heavier kit.

You get the highest score by having the highest surface area to mass ratio without using proper wings. The surface area of the tanks are fixed, the only way to increase that ratio is by having them empty.

Also, the nosecone will help you maintain speed in the low atmosphere, otherwise you won't be able to do a flare up maneuver.

Here's my trial of such a craft. 7.5tons, no wings. I didn't aim to land it, but you can tell that it will work because the flare up maneuver reduced the vertical velocity to zero. Given it's maneuverability, should be pretty easy to land it on the runway as well.

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Edit: Can I get a score for this as a regular landing? I didn't have time for a proper flight during lunch break, but given its maneuverability I'm pretty confident that if I aimed for land I would have made it. I'll do a runway landing attempt this evening.

Edited September 18, 2014 by goduranus

[chengong]

14,750kg / 0.4*2 fins * 5x skill = 92,187.5 pts

[Bilfr3d]

You get the highest score by having the highest surface area to mass ratio without using proper wings

Ah, because it turns into one of the infinite scorers. I got you now.

[goduranus]

Chengong deliberately put wings on to let me take the first place for a bit?

Well, as promised, here is the runway attempt. 15.68 tons, no wing, runway landing. Score= 78.4 tons

This score could be increased infinitely by expanding the "wing" to the left and right, as my computer can handle about 300 parts, I guess the score I can get is around 400 tons.

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Edited September 18, 2014 by goduranus

[chengong]

I put wings on it because it was my first attempt, and because I like big numbers, maybe should've used one structural panel instead.

[Yakky]

14,750kg / 0.4*2 fins * 5x skill = 92,187.5 pts

http://i.imgur.com/MGlmbXL.png

Chengong, nicely done! Very cool design that really gets at the spirit of the competition. Was it tough to fly? How many tries did it take you?

Also, what are the green things on the ends of the tanks? Looks like non-stock (or at least something I haven't seen in stock) but assuming it doesn't affect physics materially, I don't see any problem with it.

[Yakky]

Chengong deliberately put wings on to let me take the first place for a bit?

Well, as promised, here is the runway attempt. 15.68 tons, no wing, runway landing. Score= 78.4 tons

This score could be increased infinitely by expanding the "wing" to the left and right, as my computer can handle about 300 parts, I guess the score I can get is around 400 tons.

http://imgur.com/a/WxXdD

Nice! I like the scalable approach. Good enough for first place (for now) with an infinite score for using zero wings, plus 78,400 tiebreaker points (15,680 kg * 5x skill bonus) if anyone else comes up with an infinite score.

As an added challenge, can you land with fuel tanks partially full so that your touchdown speed will be high enough to get the speed bonus? I'd be curious to see what's possible with your design. You could even trim its flight characteristics by pumping fuel between forward and aft tanks. Just some ideas to take this concept further. Thanks for the great entry!

[Yakky]

Rather than a nosecone on the ship, put one of the big flat panels with lost of struts attached to it. That'll slow you down faster. The tank wings sound like a good idea. But have the tanks FULL!! After all, you get more points by having a heavier kit.

Seems reasonable to me to use the flat panels as a pure blunt instrument to slow you down. But note that the rules penalize you for using flat panels as proxy wings or tail fins. Wearing my judging hat, I would say that if your flat panels are oriented more or less perpendicular to the airflow direction (or are obscured from airflow by another part), they wouldn't count as wings. But if they are oriented somewhat parallel to the airflow, they will be deemed proxy wings and given the penalty lift value of 2.0 each. (See Rule 5.)

[chengong]

Chengong, nicely done! Very cool design that really gets at the spirit of the competition. Was it tough to fly? How many tries did it take you?

Also, what are the green things on the ends of the tanks? Looks like non-stock (or at least something I haven't seen in stock) but assuming it doesn't affect physics materially, I don't see any problem with it.

Stock ASAS unit. Some of my stock parts may look different because I use the stock part make over mod, but they function the same.

This things is actually quite easy to land at low speeds and FAR simulation tells me that its lift to weight ratio is incredible at larger AoA and low speeds so I could really achieve a nose up landing, instead of the nose down you usually have to do with winged crafts.

But it's not that stable or manoeuvrable supersonic, don't know if this would've worked without the tiny wings at high speeds.

Edited September 18, 2014 by chengong

[chengong]

84,255kg / 0.4 winglet * 5x skill = 1,053,187.5 pts

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Interesting enough, I couldn't get this design to work wingless, maybe I just havn't stacked enough SAS units, because I can't get the nose up at mach 1~2 and just crash before I could ever do it.

Edited September 18, 2014 by chengong

[Yakky]

84,255kg / 0.4 winglet * 5x skill = 1,053,187.5 pts

http://imgur.com/a/LORzM

Interesting enough, I couldn't get this design to work wingless, maybe I just havn't stacked enough SAS units, because I can't get the nose up at mach 1~2 and just crash before I could ever do it.

Nice design! I like the iterative improvement over your earlier one. A couple ideas that might boost performance and/or let you get rid of that last fin: First, try putting your SAS units near the middle instead of at the back. It might give you better torque. Second, if you leave a little fuel in the tanks, you can pump it around during the atmospheric flight to adjust your center of gravity during different flight phases. Being able to have extra weight in the rear-most tanks during your problematic Mach 1-2 speed regime might help pitch the nose up... and of course that extra fuel weight will boost your score!

But in the meantime you have the second highest score.

Edit: the 281,000 dynamic pressure reading (Q) as you come over the mountains before KSP is impressive. Did you have problems with in-flight breakup?

Edited September 18, 2014 by Yakky
Added dynamic pressure comment

[chengong]

I have custom aerodynamic failure numbers, because the default numbers are stupid low. This thing only pulls about 2~3G which means it should remain intact even with default failure thresholds. You can take a lot of Q value going prograde not doing crazy turns.

[goduranus]

Now the only thing left is to build that thing out of Kerbodyne tanks

[Yakky]

@ Chengong: See if you can get one to hold together with the default aerodynamic failure numbers rather than custom ones... this is supposed to be a stock parts challenge. Maybe add more struts or a couple wings to maintain a positive angle of attack all the way through re-entry. Or try the fuel balancing thing so that you can maintain a slightly nose-high attitude naturally.

For my (much less sophisticated) entry I maintained a positive AoA all the time and was able to keep Q below about 160,000. But if I ever let the nose drop... disaster. Even so I still had to be veeeerrrry careful with any maneuvers to avoid spontaneous disassembly.