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Stock Payload Fraction Challenge: 1.0.5 Edition


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Maelstrom Vortex, I've added your entry to the leaderboard. Your entry may not have the highest fraction but it is fully recoverable and encloses the payload in a proper cargo bay, it seems to be more practical for regular game use rather than chasing percentage. Well done!

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Ugh, triple replying to my own thread, but I have an entry. I made an asparagus staged turbojet/RAPIER/LV-N hybrid, the Aerosparagus.

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38,354kg on the pad and 14,450kg in orbit gives a 37.68% payload fraction. I had 280kg of fuel left and lost 106kg of fairing due to, uh, a staging error. So theoretically I could hit ~38.6%, and a better pilot might get it higher still.

Edited by Red Iron Crown
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Can't have just you replying to yourself!

Here's 44% to a 200km orbit - obviously could do better - but as I had spare fuel I used it up. If we count the weight of launch clamps then it's 43.2%, but I feel happy not counting them :)

Rapier (used air breathing mode only), and lv909, also features wings that tend to explode off - fortunately by the time they are that hot they aren't needed any more.

The trick is to build high speed low to get the thrust up very high; so I learnt something from messing about with space planes yesterday. N.B. Diving back down in a rapier powered plane to build speed works really well.

50% is tantalisingly close ...

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Just when I thought my rocket was reasonably well-optimized and approaching the limit of possibility along come a couple of entries that put it to shame. :)

Fantastic fractions from those designs, Slugy and metaphor, I've added you to the top of the leaderboard. It's looking like the RAPIER is the key to high payload fractions.

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Here's one with 50.23% payload fraction (58650/116770), 8 rapiers and 4 turbojets on the first stage, 1 skipper on the second stage:

http://imgur.com/a/umjhl

Congratulations - is this the first ever 50% payload fraction to orbit? Might well be a KSP first :)

Are the jets there to help get the speed up during the earlier part of the ascent?

Time to have a think :)

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Congratulations - is this the first ever 50% payload fraction to orbit? Might well be a KSP first :)

Not in 0.9...

Anyway, I managed to get an orange tank into orbit with a reasonably weighted SSTO.

B4D10A608EDB8ACD6A688AF536612969EAEA998C

120t at launch 36t to orbit, well it has some clipping. That fuel section seems to be better off inside...

SPH view: http://images.akamai.steamusercontent.com/ugc/534018596492242389/6D6EE0B3AB8B867BBDA5D05A2AD3776FB671D78A/

36/120= 30% cargo fraction for a spaceplane.

Edited by Radam
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Radam, that looks like a great plane, but this challenge requires that the payload be decoupled in orbit and I don't see how that one could be. As for clipping, if the only thing clipped is that fuel tank into empty space in the cargo bay (leaving room for decoupling) that would be within the spirit of the rule.

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54.4% - I hope I haven't broken any of the rules...

A very light craft so that the nuclear thrusters can lift.

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[Moderator edit: removed all that base64]

[edit]I just realised there is actually no payload (I didn't read the rules correctly) - so this is probably a pretty bad example.

Edited by peters
Removed all that base64
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Are the jets there to help get the speed up during the earlier part of the ascent?

Yep, the turbojets have a significantly higher TWR than the rapiers off the pad, and they're not too bad at the higher speeds either.

I also tried with a poodle upper stage, but it needed higher TWR to counteract the still-significant atmospheric drag.

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  • 2 weeks later...
Yep, the turbojets have a significantly higher TWR than the rapiers off the pad, and they're not too bad at the higher speeds either.

I also tried with a poodle upper stage, but it needed higher TWR to counteract the still-significant atmospheric drag.

Wow, Metaphor, I can't duplicate the gravity turn with your craft... that is some tricky flying!

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The Xylol SSTO was designed primarily to be pretty, a "clean" all stock Fully Reusable SSTO. Despite this it can lift 36 tons of cargo to an ~80 km equatorial orbit. Weighing on the pad at 155.9 according to stock engineer's report (155.06 according to MJ) that gives it a cargo to orbit capacity or 23.09% (23.22% according the MJ).

To reach orbit with 36 tons of cargo: Launch with one pair of jet fuel tanks empty. Take off at 25° to 5 km (Do not exceed 25° during take off), then 15° to 10 km (should be exceeding 500 m/s at 10 km), then 20° to apogee, coast at 10° and circularize at apogee. Turn off jet engines when they flame out (custom01), close pre-cooler intakes (custom06) when Rapier engines switch to rocket mode.

For landing I used MJ to see a predicted landing spot. Retro burn at antipolar to the spaceport achieving a periapsis of 41.6 ± 0.1 km with the predicted landing spot at the space port. Re-enter at at a 30° angle until the spot moves 100-30 km before the space port then level off to 10° until the spot returns to the spaceport, repeat until reaching 1500 m/s at which point you can't do an angle of attack that steep. Continue at 10° until reaching 500 m/s, then dive at -45° until below 10 km, then turn around if overshot spaceport or simply level off at 3 km. Turn on Turbo Ramjet engines to ~66% until close to spaceport, then to 33% while landing such that landing speed is between 100-150 m/s.

My contender is provided below as is with two locked X200-32 tanks as dummy cargo mass. The rules don't say the cargo needs to be one mass, but it can launch with one Jumbo-64 instead.

http://www./download/xrf7naptx143p27/Xylol_SSTO.zip

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Edited by RuBisCO
added vital detail
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Fantastic entry, RuBisCO! I've been struggling to get a Mk3-based SSTO working for payloads that won't fit in a Mk2 bay; your design looks like it works well with that large payload and delivers a good fraction to boot!

I'll add you to the leaderboard. :)

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Thank you, I do have some questions though:

1. Do the pre-coolers do anything? I just have them on their because I *think* they do something, could they be replaced by any other kind of intake? I went with ram air intakes over the cones because they of aesthetics and lighter weight, the cones can be shut off and that means less drag, but when I shut off the pre-cooler intakes early in the flight profile I notice no benefit. So I don't know if the drag is appreciable.

2. Every strut is sacred? I strutted the wings to reduce deformation and without them... your going to have a bad day, but how do stuts work exactly? I figure they need to attach parts to parts that are not directly attached together. That rear chime is the linch pin though, but it does not need to be strut-ed to the inner engines, here in Xylol SSTO A I prettied the struts even more and have it connected the wing parts, it performs the same.

3. Why do RCS cause a lot of drag? It seems to be depended on part count and not just RCS type, here in Xylol SSTO B I minimized RCS thusters to what is absolutely needed for travel along every dimension, even so I see an appreciable performance loss and do not recommend lifting more then 27 tons with it.

4. How do cargo bay work? The code seems a bit wishy-washy. Xylol SSTO B I have to launch with cargo bays open, then close them before take off to make sure the RCS tanks and docking ports are counted as inside the cargo bay and thus drag is negated, if not it won't even make orbit with 27 tons.

http://www./download/8umhcpp8wg4n457/Xylol_SSTO_A&B.zip

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1. As near as I can tell, a precooler is just another inline intake+LF tank part. (Do we really need so many of these?)

2. Struts apparently produce a disproportionate amount of drag, so minimizing the number of them is a useful goal (I wasn't aware of this when I made my entry, I should see if it performs better with no struts). Some are necessary though, can't have the ship being a wobbly mess.

3. Might be related to #2, perhaps physicsless parts are having drag troubles. *shrug*

4. I have seen some reports of Mk3 cargo bays not always blocking parts from the drag calculation. I haven't done any testing to confirm it, though. In theory everything fully inside a closed cargo bay should be out of the airflow.

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Ok, here is my attempt :

- 28.98 total weight

- 7.18 payload weight (mea culpa, including a small diameter decoupler)

- 24.78% fraction

Single Stage Spaceplane, stock parts, 34 parts (without payload).

Made it to a 75x75 LKO, and safely landed at KSP with 300+ fuel units still in the tanks (so with less safety margin, could go for a 26.5% fraction).

Can fly without auto-pilot, but SAS is still pretty much needed.

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I might update it with less fuel to get the 5th rank (and get the decoupler on the ship).

Hardest part is landing (as I want to land it at KSP, without any autopilot).

The ship is nice and has everything a spaceplane should have to lift sats to LKO.

But for a cargo bay of this size (mkII small + long), hard to find 7.2 tons payload

EDIT : please, better take this one as my entry - here the decoupler is on the ship, not on the payload.

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27.45 / 7.16 and a difficult landing (too much weight on the tail !!!)

Edited by Maukse
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I calculated your new payload fraction as 26.08% and bumped you up to 5th, Maukse. You could use ore bays to make a denser payload, you can fit 10 tons worth in a bay that size.

Thanks for the advice, I'm just wondering any "in-game" use of the full payload ... yesterday made an orbiter-lander duo, a little bit less than 6 tons, with full equipement and filling all the bay, I don't see what kind of usefull probe could go to 7.2 tons on such a bay (maybe a space tug with offset on some radial monoprop tanks)

I may give a try for a stock MK3 spaceplane - the Xylol looks pretty nice, I'm just a bit affraid of the piloting.

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Yup, I just dropped around here, and my longsword gets into the Leaderboard too, snugly somewhere around the middle:

VRkrw3A.png

5pcBwEE.png

With 146.847mT full and 36.4mT of payload (Big Red, ported on both sides with Sr. ports), that works out in my book to 24.78%, putting me on the lucky number seven. And with RCS, docking, and recovery systems and stuff thrown in! And I reckon I can improve on the ascent, I didn't get toasty enough to burn anything and switched modes at around 1,200m/s.

Edit: I just re-read the rules, and I promise all clipping is legal and without the use of F12 (or ALT-Z in my case). Too buggy to be worth it now that we have gizmos, plus we have to worry about unaerodynamic open nodes. For more pictures and details, including download, go to its post. Note, too, that it was built and posted before the (amazing) post into drag reduction measures exploiting the RAPIER's rear node came into being. Not to mention, aesthetics. The tanks on the wings are for show and containing the intakes.

Rune. Low TWR still rules. :cool:

Edited by Rune
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Well being a little bit competitive I have to demand I be moved up the board for I have successfully gotten my Xylol A to lift 41.7 tons of cargo out of a total (stock engineer's report) weight of 161.6 tons, that is 25.80%. I had made a mistake adding up the cargo mass, when I remove the cargo the craft weight is 119.9 tons, so it is 41.7 tons, not 41.825.

To lift 42.7 tons: start with one pair of jet fuel tanks empty, close bays on the runway for good luck or what ever, take off at 30° to 10 km, then at 0° until air speed exceeds 600 m/s then 20° to apogee and then circularize.

I think I might be able to put in an extra ton but pretty sure I won't have enough fuel for return then.

Also I have made a Xylol D with extended cargo bay which has lifted 36 tons.

Make a game called Kerbal Rocket Program. No jet engines allowed for reaching low orbit!

Originally the game lacked space plane parts, they have slowly been added from modders and because of community demand.

Edited by RuBisCO
updated with corrected numbers
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