Stock Payload Fraction Challenge: 1.0.5 Edition

[Val]

We'll see if things change significantly before starting a new board. Aero doesn't seem to be changing, and I'm not sure any of the new parts will be relevant (maybe the new rocket engine, depending on its stats).

It was these lines that prompted me to think that maybe things will change.

Source (snips)

• Physics constants and ablation tweaked.
  

• Heating from engine exhaust improved and rebalanced.
  

• Add missing drag cube overrides for hollow parts.
  

• Fixed issues with intake logic and display airspeed.
  

Not all directly aero related.

May impact ascent profiles due to changes in heat.

Some designs need revising, because jet exhaust does damage again?

Changed drag on hollow items. Just cargo bays or other parts too?

Changes to intake logic? The sentence is ambiguous. Could be a display problem.

It's just speculation on my part. I guess, we'll have to see.

[EvermoreAlpaca]

A very nice design. Is it pure RAPIER? Looking at the pictures I can't really figure out the engine layout. I see 9 engines in staging, but I can only see 8-ish engines in the pictures.

8 RAPIER, 1 LVN. I tried swapping in 2 whiplash and the performance took a surprisingly dramatic dive, I believe due to added drag.

[tewpie]

I tried converting my multistage into a fully reusable SSTO, here's the result:

Scarab Mk2 SSTO (.craft)

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Payload fraction: 50.55%

Ascent Profile:

1) 9 degrees pitch up after takeoff.

2) At roughly 10km, throttle down briefly to 80% to avoid nosecone exploding. Throttle back to full after a couple of seconds (have to play this by ear).

3) At 20km, fire nukes.

4) At 24km, switch to closed cycle.

5) Still holding 9 degrees, burn until AP is 75km.

Going to backport the optimizations I made for this into a new multistage version. Hoping to break 55% with that one

[Right]

Alrighty, took forever to get this one worked out. Lots of number crunching and experimentation...wish I had more to show for it! Heres my rocket entry.

Craft file: https://drive.google.com/open?id=0BwgWaXQEa1uwYVB1THNLOXBCOFU

Launch mass: 1153.6t

LKO mass: 330.064

Payload fraction: 28.61%

Mechjeb flys it most of the way. I'll include a screenshot of the important variables (Orbit alt, Limit AoA, and ascent path figures). Once apoapsis is reached, it needs to be switched to manual.

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I wish my design was special, but the unique thing I have to offer here I think is this mechjeb ascent profile - its excellent. I used it on Nefrum's craft that I was failing at getting up and it managed it perfectly with fuel to spare. For rockets with TWRs similar to ours, this should save you a lot of time in laboring through careful test flights. In fact, I added a bit more payload to Nefrum's rocket thanks to the spare fuel and got a 28.8% fraction... *nudge nudge*

[Val]

I tried converting my multistage into a fully reusable SSTO, here's the result:

Scarab Mk2 SSTO (.craft)

Payload fraction: 50.55%

OMG!!! You're right on my heels.

Big GRATZ on joining the ranks of the 50% payload fraction SSTO club

Should I start preparing, to have to beat you?

Edit: Also big Gratz to Right for getting Top Rocket spot

Edited October 8, 2015 by Val
New smiley

[Red Iron Crown]

Tewpie, great entry, added to the board. It's agonizingly close to the top SSTO spot, I have to wonder how many times you tried the ascent looking to squeak out that last 0.03% (I can't believe how close the entries at the top are, we must be approaching the theoretical best).

Right, congrats on reaching the top of the rocket board! Am I right in thinking that is asparagus staged? Also, your vessel name is likely accurate for a lot of entries here.

[Right]

Thanks you two! And it is asparagus.

Haha, I figured the name would be relate-able

[Right]

@Red Iron Crown - are any of the following acceptable on the payload if utilized: landing gear, solar panels, decouplers with the ejection force set to 0, fuel cells/arrays, or cargo bays/service compartments (as long as they are not the root).

[Red Iron Crown]

@Red Iron Crown - are any of the following acceptable on the payload if utilized: landing gear, solar panels, decouplers with the ejection force set to 0, fuel cells/arrays, or cargo bays/service compartments (as long as they are not the root).

The idea is that your test payload could be conceivably replaced with another and still have the ascent work. If that doesn't tell you then you'll have to be more specific in how exactly these parts will be used, feel free to PM me if you'd rather not reveal your nefarious scheme new idea.

[Right]

Yeah, I understand the spirit of the challenge, but I'm an exploiter so I have to make you spell out the rules! I was going to use going to use an ion engine for the last bit of orbit on a small SSTO, but the little panels are too heavy and too much drag to justify. Putting the tracking ones in a service compartment on the payload until the appropriate altitude might have done the trick...but its too gimmicky anyways. Good for cool points though.

EDIT: I'd love to see someone make this work. An ion could push a craft (1.25m inline) from a 37k circular orbit into 70k. 1 Engine overtakes drag at that altitude and tracking solar panels don't break. Main concern is losing the sunlight. My estimates predict you have a maximum of ~9 minutes of light. Did some math and tests, nevermind.

On that topic, anyone know how the drag gets added up on phsyics-less parts? I heard they add the drag to the root part, but what if the root part is also physics-less, or extremely well occluded? The additional drag might be undetectable. If so, it might be kind of silly considering you could make a wall of batteries or something and not get drag penalties.

Oh, can I put my mechjeb computer inside a service compartment on the payload? It doesn't add any mass to the payload, but it still has some annoying drag if its radially mounted.

Edited October 10, 2015 by Right

[Val]

On that topic, anyone know how the drag gets added up on phsyics-less parts? I heard they add the drag to the root part, but what if the root part is also physics-less, or extremely well occluded? The additional drag might be undetectable. If so, it might be kind of silly considering you could make a wall of batteries or something and not get drag penalties.

Hmm. That's not how I understand it to be working.

The drag is added to the first non-physicsless parent.

But the point about, "if the parent is occluded, do the physicsless part also get occluded, even if they are outside the occlusion area," is still an interesting one.

Oh, can I put my mechjeb computer inside a service compartment on the payload? It doesn't add any mass to the payload, but it still has some annoying drag if its radially mounted.

Just install MechJeb and Engineer for all! Then you don't need the parts.

[Red Iron Crown]

Yeah, I understand the spirit of the challenge, but I'm an exploiter so I have to make you spell out the rules! I was going to use going to use an ion engine for the last bit of orbit on a small SSTO, but the little panels are too heavy and too much drag to justify. Putting the tracking ones in a service compartment on the payload until the appropriate altitude might have done the trick...but its too gimmicky anyways. Good for cool points though.

Panels used this way would have to be counted as part of the lifter rather than the payload, as they are contributing substantially to the ascent.

On that topic, anyone know how the drag gets added up on phsyics-less parts? I heard they add the drag to the root part, but what if the root part is also physics-less, or extremely well occluded? The additional drag might be undetectable. If so, it might be kind of silly considering you could make a wall of batteries or something and not get drag penalties.

AFAIK Val is correct, the drag area (but not drag coefficient) is added to the first physicsful parent part. Not sure how occlusion works for them.

Oh, can I put my mechjeb computer inside a service compartment on the payload? It doesn't add any mass to the payload, but it still has some annoying drag if its radially mounted.

No objection to this (IMO MechJeb should go partless anyway, so I don't mind considering it part of the command pod in the payload).

[Right]

Just install MechJeb and Engineer for all! Then you don't need the parts.

Ah good idea! Thanks. And thanks for the exception (for MJ) Red Iron Crown.

AFAIK Val is correct, the drag area (but not drag coefficient) is added to the first physicsful parent part. Not sure how occlusion works for them.

Interesting about the drag, I'm going to port the rest of this convo to gameplay questions for more discussion!

[silks]

Hot Cosby - 24.28% - Download

A simple low tech, unmanned SSTO. Protip: 1-segment fairings are the best nosecones.

Total Launch Mass 21.655 (0:00)

Payload Mass In Orbit 5.259 (1:44)

[Red Iron Crown]

silks, that's a great low tech design, but I'm afraid as shown it violates the "payload must be inert" rule as it appears some of it was used as ballast for balance. See discussion of this rule in this post. Would your design work with the payload tanks fully filled and disabled for the entire ascent? If so I'll be happy to add it to the board.

[silks]

Tested it with ore and rcs tanks and had no problems. Even improved the ratio a bit - to 24.32%.

Ore payload version

[Red Iron Crown]

Thanks, silks, I've added your entry to the leaderboard.

[Johould]

Tewpie, if you used Pilot Assistant to fly the Scarab Mk2, what controller settings did you use?

[Bomaye]

The White Knight replica testing

Craft: https://drive.google.com/file/d/0B4NjxbmXIiYwcDN1RG1oWFVYdU0/view?usp=sharing

Take-off: 396.84t (SS said .81 dunno why it jumped)

Cargo to orbit: 163,09t

Payload fraction: 44,09%

Not bad for something I might need one day

http://imgur.com/a/rTRZW

Edited October 18, 2015 by Bomaye

[Red Iron Crown]

Bomaye, that's an interesting entry but I have some questions before adding it to the leaderboard:

- Was the Rhino used at all during the ascent, or any of the fuel in the payload?

- What is going on in pic #7, shows a lot of engines with fuel bars but the resource panel shows no fuel or oxidizer capacity?

[Bomaye]

All fuel tanks was locked on cargo, and Rhino not in use.

Pic#7 is just showing departure of cargo and is the staged only on and no stage.

[Red Iron Crown]

Thanks for the quick reply and confirmation, Bomaye, I've added your entry to the board.

[Bomaye]

My humble apologize for cheating, the vessel was using monoprop from the payload. The result became a little better after a quick fix

So I got this result:

Craft: https://drive.google.com/file/d/0B4NjxbmXIiYwYmhXSVM1cDNJZk0/view?usp=sharing

Take-off: 363,8.t

Cargo to orbit: 163,22t

Payload fraction: 44,86%

http://imgur.com/a/FcZ7U

[Red Iron Crown]

Thanks for the update (and your honesty), Bomaye. I've updated your entry and moved you up a few places on the leaderboard.

[Bomaye]

Red Iron Crown, can I clip cargo in cargo bay to increase weight? (I see its done before, after trying get same payload up)