SRB Spaceplane Challenge

[Xeldrak]

It's been a while, hasn't it?

Well, I was in the mood to host a small challenge. So here it is:

Your goal is to build a...contraption that starts from the runway, using only solid rockets engines. You have to start in a horizontal fashion, using wings to fascilitate your liftoff.

So, here are the Rules:

• Your craft may only use SRBs for propulsion.
  
• Your craft must only stock parts.
  
• Your craft must use wings to fascilitate liftoff.
  
• No liquid fuel on your craft allowed.
  
• You craft can shed parts during its flight.
  
• Your thrust vector during launch must be parallel to the ground.(*)
  

(*)Since this might cause confusion, let me explain: Your craft must launch like a plane. Building a horizontal rocket, lifting it to a vertical position using SRBs and then launching the regular way (or using other workarounds) is a no-go.

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Scoring

Your score S is calculated in the following way:

S = (Maximum Apoapsis in km) x (Multiplier)

Should your Perapsis be over 70km (i.e. you achieve orbit), your score is calculated like this:

S = [(Maximum Apoapsis in km)+(Maximum Periapsis in km)] x Multiplier

Round your score down to full points.

Your Multiplier is 1 by default. You can raise it by

• +0.25 by returning your Kerbal savely home
  
• +0.25 by achieving Orbit (Perapsis > 70km).
  
• +0.25 More power! All your SRBs are set to 100% thrust
  

Leaving the Kerbin SOI will disqualify you.

Please post screenshots to validate your claim

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Example Flight

I present you the Boxspear:

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My maximum apoapsis is 437.402 km. I did not reach orbit, but my Kerbal returned savely home, raising my multiplier to 1.25.

437.402 x 1.25 = 526.7525

Rounded down, this leaves me with 526 points.

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Highscore

1. cake>pie - 243,379 points
   
2. manni01 - 25,105 points
   
3. Kasuha - 782 points
   
4. Xeldrak - 526 points
   
5. capi3101 -78 points
   

Edited September 3, 2014 by Xeldrak

[manni01]

I did have a very successful attempt and every thing went well, all the multipliers and everything. Just one issue. I couldn't get a screenshot with the number of the periapses and apoapsis. Idk if this is going to disqualify me. This is because I have to press fn + f1 to get a screen shot, and apparently pressing fn makes the info go away (3rd world mac issues ). Even I barely remember the numbers exactly. But I will estimate my actual distance. and for safe keeping to, I will subtract 3000 points from my result, because I might guesstimate my numbers too high. I think I had an apoapsis of ~15,500,000 and a periapsis of ~560,000. Here are some screenshot on the way of my attempt:

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My result is: (15,500 + 560) x 1.75 = 28, 105

- 3000

is 25, 105

Edited September 1, 2014 by manni01

[Wanderfound]

I'll have to strip some of mine down:

[Xeldrak]

Ah, good that you posted these pictures, Wanderfound. This reminded me to add the 100% stock parts rule.

Otherwise comparison is just impossible.

[BagelRabbit]

Are parachutes allowed to facilitate descent... and are Separatrons okay to use? I'm probably going to do this, sounds like fun.

Reserved for my entry.

[Wanderfound]

Are you allowing the use of tweakables for thrust limiting? It'll be more challenging if you're obliged to use 'em fully fuelled at 100% thrust.

[Xeldrak]

Yes, parachutes are allowed.

Seperatrons are also allowed.

Well, using the thrustlimiter is okay.

Let me add the option to increase you multiplier by another 0.25 is all your SRBs are set to full power. I hope this is a good compromise.

[Wanderfound]

Bonus cred for Deadly Reentry? I can see a distinct possibility of burning up during ascent on this one.

[Xeldrak]

Nah, I'm a big fan on stock challenges. Everyone should be able to participate and achieve maximum points with a fresh vanilla KSP installation.

Also: Is reserving a place for your entry a thing now? Seems like I've been away far too long.

Edited September 1, 2014 by Xeldrak

[cakepie]

Done!

tl;dr: 82,290km / 79,963km; orbit attained, all boosters running at full power. Theoretically should have been able to return Kerbal home, but I messed up, so didn't get that bonus.

(One booster only partially filled, though, because I realized in earlier attempts it had too much delta-V and I wasn't going to rearrange the whole damn craft just to replace that with something lighter.)

Score:

(82290 + 79963) * 1.5 = 162253 * 1.5 = 243,379.5

Okay, here's the behemoth Jeb's flying today:

Business end:

Takeoff...

First stage separation -- it barely takes us to 3500+m. Now second stage...

 

This second stage separation is a thing of beauty, somehow I managed to choreograph it such that none of the wings collide.

Third stage is 3x RT-10

Then 2x BACC, then just one

 

Finagling with the interface to plan a maneuver for exactly the delta-V that the RT-10 wll provide...

Let's not forget to separate that spent stage.

Burn.

Nice.

Ditched the RT10, making some adjustments to seperatron staging for as fine control as possible. (For some definition of "fine", lol)

Something like this, maybe?

Burn.

This next.

Done.

At this point, I have 18 separatrons left and Engineer reports 487m/s delta-V, but it turns out I made a mistake in arranging them in line with one another. Out of the 24 separatrons in total I have on the cockpit, only the first 8 are effective -- the rest just shoot ineffectually at the next separatron below. Consequently, Jebediah Kerman, lost in space. In another alternate universe where I did not make this dumb mistake, landing and recovery would have been fairly trivial -- plenty of delta-V to spare, in fact. Oh well.

Edited April 17, 2018 by cakepie
success!

[Xeldrak]

@manni01 You put me between a rock and a hard place. This is a very nice entry but you are missing the most vital information.

For now I will add you to the highscore. But should any complaints arise I might have to remove you again.

Edited September 1, 2014 by Xeldrak

[Kasuha]

The idea of reserving a post for an entry is IMO one of the less bright ones. It takes up space, it does not add anything useful to the thread at the moment, it does not guarantee you will actually make an entry, and if you happen to make an entry and edit the post, it does not count as an update to the thread and nobody may notice - so you still need to make a new post at the end.

Anyway - my entry. I'm not sure if it counts, I was not trying to circumvent any rules but at certain stage still in the atmosphere that thing does not resemble a plane very much. I could attach some wings to it just to keep the form but it does not need them.

Also I'm sure I could reach even higher apoapsis but I did not want to repeat it too many times - I had to reduce amount of fuel in that last SRB or it would escape into interplanetary space. Still, all SRBs are at 100% thrust so I believe I should be getting all multipliers.

If my entry counts then my score is (475 + 2258) * 1.75 = 4782

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[manni01]

@Xeldrak Yeah I know. I tried this multiple times, but the variables that i have to control are too many. My other attempts all end up outside the solar system or just in orbit. I even tried to be fair by subtracting 3000 points, but I see why people would complain. Lets hope no one would be like: "huh, I'm second place, but this manni01 guy is first. Ohh I can get rid of him by complaining... nice..."

[cakepie]

Done!

Once you've figured out a general ascent profile and understand the delta-V involved to get out of the atmosphere, the rest is down to trying to find the right combination of maneuvers using seperatrons to fine tune as best as you can.

Leaving the Kerbin SOI will disqualify you.

Earlier (when I mistakenly used my non-stock copy of KSP) I mentioned this was a tough obstacle -- and it still is. A little delta-V goes a long way up there, so it can be fairly tricky especially if you've cultivated a habit of doing beautifully optimal transfer burns. For this, there is a lot of "find the suboptimal burn of exactly so many m/s that will increase Ap/Pe without escaping Kerbin".

Oh, and don't arrange seperatrons blocking one another. Silly me. =/

Edited September 2, 2014 by cake>pie

[Cirocco]

Question: to which degree is RCS use allowed? Can I use RCS thruster blocks to make course corrections/adjustments? Can I use the newly added RCS-propelled engine? Is there a limit to how much RCS I am allowed to bring along?

[TimberWolffe]

Okay so I have a few questions

1: What's the bonus if we get in orbit of the Mun

2: Can we use monopropellant to de-orbit our kerbals if we somehow reach HKO

3: Is it okay to use SRBs to launch a space plane which then returns to kerbin and uses liquid fuel to land safely?

[John FX]

Question: to which degree is RCS use allowed? Can I use RCS thruster blocks to make course corrections/adjustments? Can I use the newly added RCS-propelled engine? Is there a limit to how much RCS I am allowed to bring along?

Myself I would say that using any fuel except solid would be against the spirit of the rules, if not the letter.

This is a SRB spaceplane challenge, not an RCS challenge after all.

The S stands for Solid so if you can make your Mono solid then go ahead but it won`t come out of the nozzles if you do..

Okay so I have a few questions

1: What's the bonus if we get in orbit of the Mun

2: Can we use monopropellant to de-orbit our kerbals if we somehow reach HKO

3: Is it okay to use SRBs to launch a space plane which then returns to kerbin and uses liquid fuel to land safely?

The rules say no leaving Kerbin SOI, also the rules say no liquid fuel on board. As for Mono, see my post above.

C`mon people, how hard is it to only use solid fuel in a solid fuel only challenge?

[TimberWolffe]

Myself I would say that using any fuel except solid would be against the spirit of the rules, if not the letter.

This is a SRB spaceplane challenge, not an RCS challenge after all.

The S stands for Solid so if you can make your Mono solid then go ahead but it won`t come out of the nozzles if you do...

I smell separatron course adjustment

[Xeldrak]

Seems like John FX understands the challenge

But let me answer these questions myself, I will mosty just quote the original post:

To which degree is RCS use allowed?

Your craft may only use SRBs for propulsion.

Can I use RCS thruster blocks to make course corrections/adjustments?

Your craft may only use SRBs for propulsion.

Can I use the newly added RCS-propelled engine?

Your craft may only use SRBs for propulsion.

Is there a limit to how much RCS I am allowed to bring along?

No, but your craft may only use SRBs for propulsion.

What's the bonus if we get in orbit of the Mun

Leaving the Kerbin SOI will disqualify you.

Can we use monopropellant to de-orbit our kerbals if we somehow reach HKO

Your craft may only use SRBs for propulsion.

Is it okay to use SRBs to launch a space plane which then returns to kerbin and uses liquid fuel to land safely?

No liquid fuel on your craft allowed.

I hope this answers all of your questions.

[capi3101]

Alright - it's been a while since Xeldrak's done a challenge; it's been a while since I entered in one of Xeldrak's challenges. Behold the Flaming Sack of Crap 7!!

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Alright, so I'm claiming a maximum Apoapsis of 52,250 meters. I claim a multiplier of 1.5 - Jeb came home safe and I didn't tweak any thrusters. So, doing the math, I claim a score of 78,375 points, second place as of this post. Pretty sure I followed the rules/spirit of the challenge, but if not y'all let me know.

[Xeldrak]

Thanks for the entry, capi

However, I must inform you that points are calculated with kilometers in mind. So its 52.250*1.5=78.375 therefore you will get 78 points

But I'm sure you can do better

Edited September 3, 2014 by Xeldrak

[Bilfr3d]

Erm.... what if I have a really short/strong turning angle, and turn upwards before the forwards movement catches up? If that makes sense...

[cakepie]

Erm.... what if I have a really short/strong turning angle, and turn upwards before the forwards movement catches up? If that makes sense...

I suppose this depends on how you achieved the pitch up turning. Xeldrak said (emphasis mine):

You have to start in a horizontal fashion, using wings to fascilitate your liftoff.

<snip>

Building a horizontal rocket, lifting it to a vertical position using SRBs and then launching the regular way (or using other workarounds) is a no-go.

Which I'd interpret to mean that the pitch up turning maneuver should be accomplished using wings and control surfaces -- your SRBs should all be pointing toward the back of the craft and contribute purely forward velocity, and not angled to help you get the front to lift up.

Edited September 3, 2014 by cake>pie
spelling

[Xeldrak]

Cake is basically right. If you achieve this turn by controlsurfaces everything is fine.

[TimberWolffe]

I had a bit of a thought and I'm just checking it through here before I keep going with the design

(none of my...7? have worked so far, there just wasn't enough wing for the thrust and they all pitched down off the end of the runway. Jeb's been slammed into the drink at 800m/s at least 6 times.)

Anyway, are we allowed to use separatrons pointing diagonally backwards at both the front and rear to lift off the ground, then use wings and control surfaces to pitch up and rocket out of the atmosphere? Also I assume we're allowed to have the landing gears arranged in such a way that the nose is pitched upwards at about 3-4 degrees on the runway?