Ōsumi Challenge: Get to orbit, SRBs only, totally unguided

[TruKaveKi11er]

On 12/17/2016 at 4:22 AM, Red Iron Crown said:

@Jestersage There is no requirement that stock has to be a playable option for a challenge, lots of challenges require FAR or BD Armory for example.. There is no reason to imply that the OP is somehow being dishonest or has an ulterior motive by requiring a mod.

If you don't like this challenge you are free to not participate; I'll ask you to not post about the mod requirement any further here as it is distracting from the actual challenge itself.

I WILL complain about it further, because i just did the challenge with stock, made a cool rocket, recorded it, edited the video, and now i can't post it because it won't count.

I put a lot of effort into this rocket, and you din't even put a warning that you can't do it with stock, and its not obvious that you can't. Also, if that's true, then how is there a ''first person to do it stock", if no mods (aside from pure visual mods) are allowed aside from the required one?

[Gaarst]

4 minutes ago, TruKaveKi11er said:

I WILL complain about it further, because i just did the challenge with stock, made a cool rocket, recorded it, edited the video, and now i can't post it because it won't count.

I put a lot of effort into this rocket, and you din't even put a warning that you can't do it with stock, and its not obvious that you can't. Also, if that's true, then how is there a ''first person to do it stock", if no mods (aside from pure visual mods) are allowed aside from the required one?

Where in the OP is it written that it's not allowed without mods?

Mods are strongly recommended because there is no trivial way to stage a rocket without pressing the space bar in stock, but if you managed to do it, the achievement is only greater.

[TruKaveKi11er]

20 minutes ago, Gaarst said:

Where in the OP is it written that it's not allowed without mods?

Mods are strongly recommended because there is no trivial way to stage a rocket without pressing the space bar in stock, but if you managed to do it, the achievement is only greater.

It doesn't say it anywhere, i'm just a bit annoyed that you have to make an SSTO if you're not using mods.

But i have a solution to my problem with me making the video with a vessel thats technically against the rules, so it should be fine now. Also I've realized why you don't want to have a stock craft scoreboard, because it would kinda ruin the idea of the challenge.

Expect me to post a rocket that has the modded parts and is entirely automated

[Red Iron Crown]

1 hour ago, TruKaveKi11er said:

I WILL complain about it further, because i just did the challenge with stock, made a cool rocket, recorded it, edited the video, and now i can't post it because it won't count.

I put a lot of effort into this rocket, and you din't even put a warning that you can't do it with stock, and its not obvious that you can't. Also, if that's true, then how is there a ''first person to do it stock", if no mods (aside from pure visual mods) are allowed aside from the required one?

No one aside from one person ever said that this was impossible in stock. You could look a bit further upthread and see that people have already done this in pure stock within the rules in the OP and submitted their entries (example 1, example 2). Perhaps you might take a lesson from these players who, rather than complaining about how unfair the challenge is to pure stock players, instead went ahead and did it in stock anyway.

Now please stop derailing the thread. If you have an entry then share it, otherwise let these players have their fun.

[Steel Starling]

Hopefully this challenge is still going and I haven't accidentally ressed a thread.

I'm working on a design for this, my only advice is: Sepratrons are the key, lots and lots of Sepratrons

[Snark]

On 1/18/2017 at 6:36 PM, Steel Starling said:

Hopefully this challenge is still going and I haven't accidentally ressed a thread.

Nah, as far as I'm concerned, it's still going for as long as anyone's inclined to contribute. 

 

On 1/18/2017 at 6:36 PM, Steel Starling said:

I'm working on a design for this, my only advice is: Sepratrons are the key, lots and lots of Sepratrons

Looking forward to it!

[Klapaucius]

@ralanboyle,  @mystifeid  This came up in my "resurrect a dead challenge challenge, suggested by @ManEatingApe.  Considering your recent entries in the Solid SSTO challenge, this might be interesting to see. @Snark what are your thoughts on KAL-1000 controllers?

[Snark]

1 hour ago, Klapaucius said:

@Snark what are your thoughts on KAL-1000 controllers?

I think they're a great idea that open up all sorts of interesting possibilities... but I also think that it's not entirely fair to lump people-just-using-timers in the same bucket with people who can use the sophisticated automation of a KAL-1000.  After all, the original Ōsumi craft didn't have fancy computerized guidance systems-- that's a big part of the point of the challenge. 

Honestly, "this challenge, but with KAL-1000" actually feels kinda like an entirely new challenge. 

Tell ya what-- maybe you'd like to spin up a new thread and call it "Automation Ōsumi" (or whatever you like), which allows the KAL-1000?  (And whatever other rule tweaks you like-- it'd be your challenge, after all.)

I'd be happy to add a link to your challenge from the OP of this one, so that folks who come here would see your thread.  What do you think?

[mystifeid]

2 hours ago, Klapaucius said:

@ralanboyle,  @mystifeid  This came up in my "resurrect a dead challenge challenge, suggested by @ManEatingApe.  Considering your recent entries in the Solid SSTO challenge, this might be interesting to see. @Snark what are your thoughts on KAL-1000 controllers?

Thanks for thinking of me but unguided or programmed is usually not really my cup of tea.

[ralanboyle]

3 hours ago, Klapaucius said:

@ralanboyle,  @mystifeid  This came up in my "resurrect a dead challenge challenge, suggested by @ManEatingApe.  Considering your recent entries in the Solid SSTO challenge, this might be interesting to see. @Snark what are your thoughts on KAL-1000 controllers?

If you restart this with a KAL-1000 I'll give it a shot but ive never tried anything like that before. 

[Klapaucius]

7 hours ago, Snark said:

I think they're a great idea that open up all sorts of interesting possibilities... but I also think that it's not entirely fair to lump people-just-using-timers in the same bucket with people who can use the sophisticated automation of a KAL-1000.  After all, the original Ōsumi craft didn't have fancy computerized guidance systems-- that's a big part of the point of the challenge. 

Honestly, "this challenge, but with KAL-1000" actually feels kinda like an entirely new challenge. 

Tell ya what-- maybe you'd like to spin up a new thread and call it "Automation Ōsumi" (or whatever you like), which allows the KAL-1000?  (And whatever other rule tweaks you like-- it'd be your challenge, after all.)

I'd be happy to add a link to your challenge from the OP of this one, so that folks who come here would see your thread.  What do you think?

I'm not sure I could pull this off.  But, I reckon @jshu could, considering the amazing entry in @vyznev Hover Challenge.

[Pds314]

Mission using the KAL-1000. Pressed play, screen froze for 30 seconds, and then I let it run itself.
This is what happens when you forget the difference between vacuum and surface delta V... but I guess it made orbit.

Liftoff. Full throttle.


Thrust limiter is set to slowly decay through the flight in a pre-determined sequence, down to 30%.


Fins are very hot, but are not longer needed as center of mass has shifted forward, so it's ok that they're gonna melt.


Fairing is overheating.


Out of fuel, but fairing is still overheating.


Fairing managed to survive. As it reliably does despite getting within a few degrees of melting point. Time to jettison it.


Vehicle unfolds solar panels as it escapes the main rocket.


Perikee is good.


Ignite stage 2.


Apokee is NOT good. 2 million meters... Which means this vehicle cannot access the southern icecap for scans. Ever. And will spend 75% if of its orbit above scanning altitude.


But hey, it's scanning the northern hemisphere, even if not optimally.

Edited May 16, 2020 by Pds314

[Pds314]

I can use the same keyframes to put up elliptical orbit relaysats. Unfortunately, the randomness of the residual velocity seems to mean they can vary in max altitude quite a lot. Much moreso than Orescansat 1.



Note the 500 km difference in apokee.

Edited May 16, 2020 by Pds314

[Pds314]

The problem is, the script is completely rigid. It has zero ability to do a conditional branch or read in a variable or check the status of anything and respond (which, to be fair, is why it's good for this challenge, otherwise KAL-1000 flight would be guided), other than MAYBE writing to another KAL and seeing if that KAL is still alive or something, then doing something specific if that KAL is dead.

So using the same script with a slightly larger relaysat predictably results in a... rather suboptimal... flight profile.


 

Edited May 16, 2020 by Pds314

[Pds314]

Regarding the subject of KAL-1000s, if you use them as part activation timers, that's all they are. I did use mine to reduce the thrust limiter as well, which is something real SRBs have, a baked-in thrust vs time curve based on propellant grain. but you can definitely do it without that.

 

Edited May 16, 2020 by Pds314

[jshu]

On 5/15/2020 at 7:59 PM, Klapaucius said:

But, I reckon @jshu could

Thanks for mentioning me here! It took a long time (wow, almost 3 months...) because I had basically no time for KSP, but today I finally finished my entry for this challenge:

The craft is fully stock and doesn't have any timers or other controllers. Thanks to @Starman4308 for the idea how to create multiple stages without using any modded parts. I simplified the construction a lot since I went for the lowest possible launchpad mass (probably at the cost of reduced reliability, though I have no idea how reliable the original construction is...).

Craft file: https://drive.google.com/drive/folders/1fFOfQmzMFiabnklVyHTF6klXHx_yysLc?usp=sharing (Please tell me if this works, I've never shared a craft file before. This link points to a folder holding the craft file and the loadmeta file. Do you need both, or is the craft file enough?)

Craft stats:

• Launchpad mass: 10.618t
• Payload mass (weight in orbit): 0.81t
• Efficiency: 0.81t/10.681t=0.0758356
• Apoapsis(*): 120.01km
• Periapsis(*): 80.17km
• Eccentricity(*): 0.0285

(*) Values are from the flight shown in the video below. Unfortunately, the craft is somewhat unreliable, so the values will most likely be different if you download the craft file above and do a test flight. It's not like "Fire and forget", more like "Fire and pray". Be prepared that you may need multiple tries to reach orbit.

Thanks @Snark for the challenge!

[sevenperforce]

On 8/9/2020 at 2:28 PM, jshu said:

Craft stats:

• Launchpad mass: 10.618t
• Payload mass (weight in orbit): 0.81t
• Efficiency: 0.81t/10.681t=0.0758356
• Apoapsis(*): 120.01km
• Periapsis(*): 80.17km
• Eccentricity(*): 0.0285

(*) Values are from the flight shown in the video below. Unfortunately, the craft is somewhat unreliable, so the values will most likely be different if you download the craft file above and do a test flight. It's not like "Fire and forget", more like "Fire and pray". Be prepared that you may need multiple tries to reach orbit.

I wonder if you could squeeze some more performance by making three of those small SRBs burn faster than the other three.

[jshu]

17 hours ago, sevenperforce said:

I wonder if you could squeeze some more performance by making three of those small SRBs burn faster than the other three.

Do you mean symmetrically (to get a different thrust curve) or asymmetrically (to make the craft pitch down earlier)?

The reason for the low thrust in the upper stage is that I may not use up all the fuel to early. I need to have some fuel left at apoapsis so that I actually reach orbit and don't just do a suborbital hop with a way too high apoapsis but a periapsis somewhere below the ground.

About asymmetric thrust on the upper stage, I tried that, but the problem is that you can only set thrust limiters in steps of 0.5, which is way too much. I also tried leaving the thrust limiters equal and slightly changing the fuel levels in some of those SRBs to get asymmetric thrust, but that didn't work either. The ultimate problem with optimizing anything on the craft is that the first stage is rather wobbly and so you don't get reproducible results.

Actually, thinking about it again while writing this reply, it needs to have the following thrust curve for maximum efficiency (assuming symmetric thrust):

1. While the first stage is burning: [doesn't actually matter]
2. After separating the first stage, we have an apoapsis of around 40 km and a periapsis of around -500km, so we need high thrust to quickly get the apoapsis above 70km.
3. Once there we need low thrust to save fuel and stop raising our apoapsis.
4. Once just a few seconds before apoapsis, we need high thrust again to raise our periapsis above 70km.

I specifically didn't know how to achieve 4. since I cannot activate any new engines without staging, so I chose an average value that somehow (not very efficiently as you noted) works for both 3. and 4..

[sevenperforce]

On 8/15/2020 at 9:02 AM, jshu said:

Actually, thinking about it again while writing this reply, it needs to have the following thrust curve for maximum efficiency (assuming symmetric thrust):

1. While the first stage is burning: [doesn't actually matter]
2. After separating the first stage, we have an apoapsis of around 40 km and a periapsis of around -500km, so we need high thrust to quickly get the apoapsis above 70km.
3. Once there we need low thrust to save fuel and stop raising our apoapsis.
4. Once just a few seconds before apoapsis, we need high thrust again to raise our periapsis above 70km.

I specifically didn't know how to achieve 4. since I cannot activate any new engines without staging, so I chose an average value that somehow (not very efficiently as you noted) works for both 3. and 4..

I mean, you definitely got into orbit, so you have that going for you regardless. I was thinking about doing symmetrically to get a different thrust curve. One possibility would be to have three of the smaller SRBs burning at a different rate so that they would die off sooner. Keep as much dry mass as possible on that stage, so if they die out just before apoapsis, all of that dry mass drops away with them and you get a higher TWR on the final burn.

If there is excess thrust on three of those SRBs, you can decrease thrust on the first stage to give it a longer burn time and help with #2.

Edited August 16, 2020 by sevenperforce

[jshu]

Thanks for helping me to optimize my craft @sevenperforce! KSP is great for learning about physics.

13 hours ago, sevenperforce said:

I mean, you definitely got into orbit, so you have that going for you regardless.

So, do you think this craft is already worth being added to the leaderboard? I may try to optimize it further, but I can't promise anything...

12 hours ago, sevenperforce said:

Keep as much dry mass as possible on that stage, so if they die out just before apoapsis, all of that dry mass drops away with them and you get a higher TWR on the final burn.

Sorry, but I don't understand this one. Do you really mean as much dry mass or as few dry mass as possible? If three of those SRBs die out sooner, then most of the mass (the fuel) is gone earlier, but I cannot actually reduce dry weight for the final burn because I can't think of any way to separate the empty SRBs without staging (or adding some other construction similar to the first stage, which would probably add far more weight than what is saved by separating three small empty SRBs...).

13 hours ago, sevenperforce said:

If there is excess thrust on three of those SRBs, you can decrease thrust on the first stage to give it a longer burn time and help with #2.

The thrust limiter on the first stage is already turned down a little. However, the main reason for this is that it controls how fast the craft accelerates after launch, therefore how fast aerodynamic flow around the fins builds up and therefore how quickly the craft starts to pitch down. Also, I still need some aerodynamic flow around the fins on the second stage once the first stage separates (for stabilization, cause sometimes it gets a little kick if the first stage SRB doesn't fall down fast enough and slightly touches the craft, and also for making it continue to pitch down), so I may not be too high in the atmosphere at that point.

 

 

[sevenperforce]

6 hours ago, jshu said:

I don't understand this one. Do you really mean as much dry mass or as few dry mass as possible? If three of those SRBs die out sooner, then most of the mass (the fuel) is gone earlier, but I cannot actually reduce dry weight for the final burn because I can't think of any way to separate the empty SRBs without staging (or adding some other construction similar to the first stage, which would probably add far more weight than what is saved by separating three small empty SRBs...).

Yeah, you'd be doing construction similar to the first stage. But do it in such a way that the dry mass of that assembly is all on the second stage.

[jshu]

4 hours ago, sevenperforce said:

Yeah, you'd be doing construction similar to the first stage. But do it in such a way that the dry mass of that assembly is all on the second stage.

Ah, ok, that makes sense. Thanks for the explanation. I'm still not sure whether I can construct something like that without adding to much weight and/or drag during launch, but I may try...