Stock Payload Fraction Challenge: 1.0.5 Edition

[g00bd0g]

Weee above 50% in almost SSTO (gear is left on ground, rest is on one stage) ... 9.187/18.263*100 = 50.3% There is little bit more performance left in the design, probably up to 51% ... Although it's kind of boring with Rapiers being so good that staging anything except for used fuel tanks does not really bring improvements.

http://imgur.com/a/w0Gs9

I am confused about the rules.

- Payload must be inert and contribute nothing but incidental body lift and command authority to the lifter (crewed pod or probe core is ok). All reaction wheels, batteries and fuel tanks in the payload must be disabled via tweakables.

Nao's entry must be using the batteries and reaction wheels in the command pod, is this legal? Beyond this, I would like to see more data on his flight, I have a hard time understanding how this entry actually flew to space with no control surfaces and no SAS, including no vertical stabilizer and a highly variable CoM (due to fuel location). Additionally, how does this thing balance on the runway with the wheels as shown? It seems only possible with super-strong SAS.

Nao, would you be willing to share your .craft file?

I do not mean to doubt the legitimacy of this flight, I am just trying to understand exactly how the above challenges were overcome.

Edited July 13, 2015 by g00bd0g

[selfish_meme]

Vertical stabilisers are overrated, SAS can provide enough authority, I have a craft file for a Mk3 Cargo SSTO with no vertical stabiliser. I do agree with you though that unless he ditches the cockpit with a separator, say a TR-18D Stack Separator for 75kg, it is not permissible. With that it would be 48.74% by my calculations.

Edit: no the rules state a manned command pod is OK, that means any torque, electricity or monoprop provided by that capsule are Ok too

[g00bd0g]

Edit: no the rules state a manned command pod is OK, that means any torque, electricity or monoprop provided by that capsule are Ok too

except it also says " All reaction wheels, batteries and fuel tanks in the payload must be disabled via tweakables."

which would leave his craft without battery or SAS.

[selfish_meme]

except it also says " All reaction wheels, batteries and fuel tanks in the payload must be disabled via tweakables."

which would leave his craft without battery or SAS.

Probably need Red Iron Crown to call it, it does seem confusing.

[Nao]

I am confused about the rules.

- Payload must be inert and contribute nothing but incidental body lift and command authority to the lifter (crewed pod or probe core is ok). All reaction wheels, batteries and fuel tanks in the payload must be disabled via tweakables.

Nao's entry must be using the batteries and reaction wheels in the command pod, is this legal? Beyond this, I would like to see more data on his flight, I have a hard time understanding how this entry actually flew to space with no control surfaces and no SAS, including no vertical stabilizer and a highly variable CoM (due to fuel location). Additionally, how does this thing balance on the runway with the wheels as shown? It seems only possible with super-strong SAS.

Nao, would you be willing to share your .craft file?

I do not mean to doubt the legitimacy of this flight, I am just trying to understand exactly how the above challenges were overcome.

All the control was from the engine gimbal And the CoM does not move while flying in atmosphere due to fuel being drawn only from the four wing-tanks. I unlocked fuel from the main tank just before going closed cycle on Rapier, and after that CoM shifts to front as the rocket fuel is used so the craft self centers on prograde in atmosphere.

Everything can be seen on the crappy video i posted. Although this video was made after i managed to get the thing to orbit properly and in spirit of trying new ascent paths and comparing fuel to orbit to know which one was better i did turn on command pod sas at the end forgetting i should not do that. But it's perfectly possible to turn the craft around only with engine gimbal and minimum throttle which was what i used in several first flights. The ~5l of oxidizer left in the video is ~15s of "rocket sas" which is plenty considering any maneuver before burn needs only to bring the craft in the general direction, as full throttle burn would give precise steering.

As for the craft: https://www.dropbox.com/s/uqjq1kj1uqe4gqz/gray%20screen.craft?dl=0 but as i've noted there is probably 51% and more in just tweaking the fuel and maybe adding reversed ram intake instead of nose cone to rapier.

[Red Iron Crown]

Regarding the command-pod-in-payload rule, it was my intention for a single pod in the payload to be able to use its reaction wheel and battery (but not monoprop, if any). The wording is a bit unclear, I'll reword the rule to be more explicit.

[g00bd0g]

All the control was from the engine gimbal And the CoM does not move while flying in atmosphere due to fuel being drawn only from the four wing-tanks. I unlocked fuel from the main tank just before going closed cycle on Rapier, and after that CoM shifts to front as the rocket fuel is used so the craft self centers on prograde in atmosphere.

Everything can be seen on the crappy video i posted. Although this video was made after i managed to get the thing to orbit properly and in spirit of trying new ascent paths and comparing fuel to orbit to know which one was better i did turn on command pod sas at the end forgetting i should not do that. But it's perfectly possible to turn the craft around only with engine gimbal and minimum throttle which was what i used in several first flights. The ~5l of oxidizer left in the video is ~15s of "rocket sas" which is plenty considering any maneuver before burn needs only to bring the craft in the general direction, as full throttle burn would give precise steering.

As for the craft: https://www.dropbox.com/s/uqjq1kj1uqe4gqz/gray%20screen.craft?dl=0 but as i've noted there is probably 51% and more in just tweaking the fuel and maybe adding reversed ram intake instead of nose cone to rapier.

Nao, thanks for the clarification, what a marvel of engineering, I am amazed it works!

[g00bd0g]

My latest attempt.

Der Snorkenklugen @ 47.7%

Not as good as Nao's, but pretty good for a larger launcher. Might be interesting to split the categories by size (1.25, 2.5, etc...) of payload, I think there are peak efficiencies achievable by each size. Might also be interesting to have standard payloads, forcing the design of the launcher to accommodate the payload instead of the other way around. Just thinking out loud, what a fun challenge!

Javascript is disabled. View full album

FYI, I renamed the craft after the flight (called test2 in the screenshots)

Edited July 15, 2015 by g00bd0g

[Red Iron Crown]

Added to the board, g00bd0g, the new high water mark for a single stage! I also calculated your payload fraction as 31,700/66,976*100=47.33%, did I misread one of the numbers (your screenies have been resized and it's not 100% clear) or was 47.7% a typo?

When drafting the challenge I considered requiring the payload to be ore or another standardized payload; in the end I decided I wanted entrants to have as much design freedom as possible. Perhaps someone else might want to run a standardized payload fraction challenge, it's a bit late in the game to change the rules for this one.

[g00bd0g]

Yeah sorry, was a typo, your numbers are correct. Also, I did eject my gear after liftoff (same as Nao, I think) which maybe counts as a stage? Staging order was wonky in 1st screenie, I eject the gear after liftoff, and decouple the payload once in orbit

[Red Iron Crown]

I missed that, I'll have to count it as multistage then. Still a great entry.

[Nich]

YES back in first place for SSTOs Even thought it is a technicality it feels so good

[parzr]

I humbly submit my entry. I come up with 56.87%. I didn't see the rule about the in game stats page till just now and can revert to take them if the Mec-Jeb page isn't acceptable.

I'm still trying to fly it to the ground for a landing and the K-prize.

My payload is 90.9 tons of fuel/ox to orbit, in a double long MK3 bay. (2.5 Big Orange tanks)

http://imgur.com/a/eDvNP#0

[Nao]

I humbly submit my entry. I come up with 56.87%. I didn't see the rule about the in game stats page till just now and can revert to take them if the Mec-Jeb page isn't acceptable.

I'm still trying to fly it to the ground for a landing and the K-prize.

My payload is 90.9 tons of fuel/ox to orbit, in a double long MK3 bay. (2.5 Big Orange tanks)

Payload fraction is "payload mass" divided by "launch mass", and according to MJ you have 562t launch mass, so it's 16% (90/562) not 56% unfortunately If you want to get higher number, take heavier payload and less fuel in the plane itself. From the pictures, with the amount of fuel left in the craft itself i think you will have no troubles going above 30% in that craft

Anyways @ Red Iron Crown, i've been thinking in making a true SSTO jet, but to be sure, if i use fairing and don't stage it before payload separation, would it be considered single stage? And could the fairing be counted as payload?

At first i tried use open fairings and use undockable cap to get the payload out but undocking destroys fairing and i refuse to pay 3+% payload fraction penalty on using normal cargo bay hahaha.

[parzr]

Thanks for that Nao. So the aim is closer to maximizing the barest minimum weight at launch, to get the payload to orbit, by percentage; and assuming you're not just transferring out all your fuel as said payload.

Edited July 17, 2015 by parzr

[Red Iron Crown]

parzr, I added your entry to the leaderboard with a corrected payload fraction. That plane may not have the highest fraction but it is still a monster! What is the part count on it, and how smoothly does the game run when flying it?

Nao, unstaged fairings do not count against my SSTO definition, which is "drops no parts during ascent". Using a fairing for a nosecone is fine, and it can be used as payload mass if you can arrange the vessel that way.

[parzr]

parzr, I added your entry to the leaderboard with a corrected payload fraction. That plane may not have the highest fraction but it is still a monster! What is the part count on it, and how smoothly does the game run when flying it?

Nao, unstaged fairings do not count against my SSTO definition, which is "drops no parts during ascent". Using a fairing for a nosecone is fine, and it can be used as payload mass if you can arrange the vessel that way.

Woo-Hoo!

Thanks. Yeah, looks like I was using fuzzy math; my prime goal for that mission was actually the K-prize so your accolades are appreciated

There's 274 parts in that beast and with most graphics settings at 50% or less it was still bad. On the ascent I set the nav-ball at about 15° and walked away from the computer with little more than an eye on it for a good 30 min.

I did try to use large items and she could hold together with 3x physics warp if in a stable position. The abusive number of Vernor engines helped.

[Frank_G]

My entry: Moray Delta II Stock SSTO spaceplane.

The fully fueled craft weighs 111.3 tons and can carry additional 41.5 tons to an 85 km circular orbit, resulting in 2.68 : 1 craft : payload ratio. This is equal to 35.3% of the launch weight. The craft can be downloaded from my craftfile thread.

Detailed mission report with visible stats as follows:

Javascript is disabled. View full album

[Red Iron Crown]

That's a great cargo SSTO, Frank_G. Before I add you to the leaderboard, can I request a screenshot of the mass before takeoff and payload mass after jettisoning it? (Not that I think there's anything awry, just want to be consistent.)

[Frank_G]

No problem. Coming up, just need to fly another round to take the screenshots

[edit] The requested screenshots have been added to the album above. Thank you!

Edited July 19, 2015 by Frank_G

[Red Iron Crown]

Thanks. I calculate your payload fraction as 27.23% (41.25/151.51*100), adding to the board.

[Frank_G]

Thank you! I set the empty craft in relation to the payload. Good you asked for the screenshots

[Nefrums]

51.2%

Two stage plane with a Rapier and a Terrier.

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Edited July 21, 2015 by Nefrums

[Red Iron Crown]

Well done, Nefrums! I didn't think we'd see a new leader on the air-breathing board, that it one tight vessel. I used "51" as the vessel name as it wasn't clear in the pics, if you have some other name for it let me know and I'll change it.

[Nich]

Ha ha well that sucks Nefrums. That was the exact plane I was about to design but I wanted to use the shock cone infront of the other command pod (which violates the rules)

Edited July 21, 2015 by Nich