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SRB Challenge (Ares-1 Style)


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SRB Challenge (Ares-1 Style)

In part a tribute to the cancelled Ares-1 rocket, the aim of the challenge is to create a Kerbal-carrying rocket that has, as its first stage, a Rockomax BACC Solid Fuel Booster as the ONLY propulsion method, then an upper stage (or stages) to get it into orbit. There are two leaderboards: one will be based purely on the amount of Delta-v the remaining craft has once placed in a 70x70km orbit (Mechjeb or equivalent required for this bit), and the other based on achievements. This is primarily a construction challenge, so Mechjeb can be used to pilot your craft, although not necessary. Ship must be stock apart from Mechjeb (or equivalent data-providing mod).

Rules

1. First stage must be the Large White Rockomax SRB ONLY (control surfaces can be placed on this though)

2. Must have a crewed Command Pod.

3. Mechjeb (or equivalent delta-v displaying mod) required.

4. All other parts must be stock.

5. Craft must be able to take off from the pad BEFORE the booster runs out of fuel.

6. Craft must be placed in a 70x70km orbit (Higher orbits will be accepted, but try to aim for this as a solid benchmark)

Submission Requirements (example below)

1. Ship name, amount of delta-v remaining in orbit, list of completed Achievements.

2. Screenshot on the launchpad.

3. Screenshot in orbit, with mechjeb window displaying remaining delta-v (if unsure what this is, see below)

4. Screenshot of any achievements you're eligible for.

Achievements

Gemini - space for 1 Kerbal +5

Two's Company - space for 2 Kerbals +5

Three's a Crowd - space for 3 Kerbals +10

Taxi! - space for 4 or more Kerbals +10

Powered Landing - De-orbit your ship and perform a powered landing. +20

Hard Landing - Crash. (but everyone survives). +5

Home Again! - Land at KSC +5

Proper Job - Achieve an orbit of 421x421km (orbit of the ISS, Ares-1's intended destination) +10

Burn Prograde! - Reach the SOI of a Moon +25

Moar Power - Reach the SOI of another Planet +30

One Small Step - Land on a Planet +35

One Medium Hop - Land on Minmus +40

One Giant Leap - Land on the Mun +50

Return Ticket - Successfully return from a landing on another Celestial Body +50

Leaderboard (Delta-V)

1. Tavert - 29,066m/s

2. Tavert - 11177m/s

3. Cirdan - 538m/s

4. The Procrastinaut - 0m/s

5.

Leaderboard (Achievements)

1. Tavert +195 (Gemini, Proper Job, Burn Prograde!, Moar Power, One Small Step, One Medium Hop, One Giant Leap)

2. Cirdan +10 (Gemini, Hard Landing)

3. Tavert +5 (Gemini)

4. The Procrastinaut +5 (Gemini)

5.

Where can I find this Delta-v?

In Mechjeb, this can be found under the "Vessel Information" tab. "Vac. ÃŽâ€v" is the value you are looking for. If you have multiple values under this column, add them together.

This is my first challenge submission, any suggestions on how to improve would be welcomed. :)

Edited by The Procrastinaut
Leaderboards Update
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Any feelings on jet upper stages? Ion? And what is the minimum usage of a single BACC that counts for the first stage? Does it need to get off the pad from the very initial lighting of the BACC (so max pad mass = 315/9.81 = 32.11 t), or does it still count if some of the solid fuel has to burn off before TWR reaches 1 (max pad mass = 6.375 + 315/9.81 = 38.485 t)?

Edited by tavert
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Abusing the rules with both jets and an impractical amount of Xenon

It looks like a palm tree! I had a big debate with myself when making this challenge because of xenon, and thats why I decided to make achievements too: getting to orbit with all that delta-v is good enough, but then actually being able to DO something with all that delta-v is another thing entirely ;)

just Gemini (did you mean Mercury??)

I probably did... *facepalm*

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Here's something a little more practical then, using an LV-N: http://imgur.com/a/TaGvs#0

11177 m/s in orbit, did Gemini, Proper Job, Burn Prograde!, Moar Power, One Small Step, One Medium Hop, and One Giant Leap. It got on a return trajectory too, but only gets credit for Return Ticket if you don't have to land on Kerbin for that one... I think I went for too much fuel, and skipped the chutes, in pursuit of that last tiny bit of delta-V. 350 m/s atmospheric isn't enough to do a powered landing with a TWR barely above 1 in Kerbin gravity. A lot of the flight path was pretty wasteful, especially when MechJeb went nuts a couple times on the Duna transfer and correction burns before I caught it.

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It got on a return trajectory too, but only gets credit for Return Ticket if you don't have to land on Kerbin for that one...

Alas, unless you can "successfully return" you don't get the achievement. :wink: However, I didn't think it was possible to do that much in a single mission, wow! Updating the OP now :)

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I made one that can land on mun with about 385 m/s delta v left that doesn't do any jet or xenon trickery. Is it worth documenting with screenshots? It's nothing special. Just the SRB (which gets it about 1 or 2 m/s of speed before burning out), then a small SRB and a 4 engine asparagus stage with a 5th engine that joins in when the small SRB burns out.

I don't really like the 70km apoapsis part of the thing because a 70km apoapsis is very difficult to pull off with the nuclear rocket (even via mech jeb) because of the lower TWR. I did a 90 when I did this one.

Let me know if I should go back and document.

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any jet or xenon trickery

Hey, I resemble that remark! :P

Maybe it's just me, but describing KSP rocket designs in words alone doesn't quite do them justice. At least a pad shot would be painless to grab, right?

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k, here we go.... (should have put lights on it, woops)

On the pad:

BwKWu2D.jpg

"lift off" with 6 seconds of SRB burn left

fhVDZGZ.jpg

orbit at 72km, 2530 m/s delta v left

i29WeYV.jpg

1670m/s delta v left after mun burn

EQ00EOk.jpg

hello mun!

FBPAa5N.jpg

landed

vWFRZ4w.jpg

woops, can't get home!

O1PEADG.jpg

Edited by occar
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k, here we go.... (should have put lights on it, woops)

Cool, I like it! Solids then a little bit of asparagus topped off by nuclear is amazingly effective. I was using basically the same formula for a different challenge with this guy, for a more legitimate entry here I could've plopped the entire thing on top of a BACC.

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This one actually has the smaller SRB burning with the 4 outer asparagus engines. So the process is as follows (it doesn't match the layout).

1. Light large SRB

[lift-off]

2. Large SRB burns out

3. Dump large SRB, light small SRB *and* 4 outer engines (this is 2 stages technically, I need to restage the thing so it is one action by combining stage 5 and 6)

4. Small SRB burns out (before any side engines run out)

5. Dump small SRB and light inner engine

6.... Normal asparagus staging from here until the nuclear stage.

I haven't really seen any designs do this, and am not sure how much (if any) it gains me over putting another liquid engine down there, but I wanted something that would empty before the first pair of side engines needed dumped. It is on the bleeding edge of what the first SRB can lift off though, right before it empties, so the only other option is another FLT-200 and a LV T-30 to still take off. I think the SRB makes more sense in that weight restriction. The small SRB is 250 kN for 30 seconds, and a tiny liquid pair would be 215kN for only ~16 seconds weighing less wet 1.375ish T but .875T more when dry. I don't see how that liquid would be better.

Edited by occar
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That's what I meant, perhaps the word "then" was a little imprecise. I used the staging shown in the pad picture with mine, it does the same thing - outer liquids burning at same time as small solid. That's why I have one liquid tank between the small solid and its decoupler, so we ditch a little bit of tank weight along with the spent solid (gotta get the fuel amount vs burn time right). I got the idea from two of Nao's challenge rockets pre-forum-derp: his Smallest Eve Ascent Vehicle which had a stage of solids, and his rocket-only SSTO which was quite small with a solid and 2 nukes.

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Wait, can there be more than 1 large SRB?

Sure, but that first stage has to be one SRB and only one SRB according to the challenger. As I understand it, that's means that your ship must be light enough that the lone SRB can lift it any amount. After that, anything is fair game.

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