Take "MOAR BOOSTERZ" more seriously.

[rtxoff]

My current design has 4440/4779 m/s, which is significantly more than most of my launch vehicles have with nominal payloads.

Are you sure? Every source i saw yet stated that 4500m/s dV is the minimum to go to LKO.

I do not see a chance that your launch vehicle has that much and is still able to put a payload on it.

[Jouni]

Are you sure? Every source i saw yet stated that 4500m/s dV is the minimum to go to LKO.

I do not see a chance that your launch vehicle has that much and is still able to put a payload on it.

Atmospheric delta-v isn't too relevant, except for Eve landers. When launching from Kerbin, the actual Isp is halfway between atmospheric and vacuum values at 5000 m * ln 2 ≈ 3465 m. In practice, I estimate the delta-v gained from the (first pair of) boosters according to atmospheric values, and the remaining stages according to vacuum values.

[Northstar1989]

It's easy to get vacuum Isp over 4700 m/s with SRBs: burn the RT-10s first, because they have the best mass fraction, and use the S1s later, because they have better Isp. My current design has 4440/4779 m/s, which is significantly more than most of my launch vehicles have with nominal payloads.

The real problem is drag. SRBs have drag coefficient 0.3 instead of the usual 0.2, increasing delta-v losses and changing the optimal ascent path. It might be enough to delay the turn by 5000 m * ln(0.3/0.2) ≈ 2 km, but I'm not sure how much delta-v the ascent requires. Just delaying my usual ascent path by 2 km got me to a 203x-112 km orbit, so it might be enough to add one RT-10 for circularization.

Higher drag-coefficient means lower Terminal Velocity. Try following an ascent path where you act as if terminal velocity is about 80% of what you normally treat it as, and see how you do.

Also, while the challenge says the rocket must only use SRB's for propulsion, I see no rules about launching from the KSC. So you *could* try wheeling a rocket into the foothills of the mountains west of the KSC using wheels to increase ISP at liftoff, ideal TWR at liftoff (higher TV at liftoff), and reduce Delta-V to orbit...

Or, if you're *really* feeling like using a loophole, airlift the SSTO piece-wise into the mountains west of the KSC using a Firespitter-based helicopter (there are no rules that your entire space program must use SRB's) and assemble it on-site using dockin ports- or even build it in the mountains using Extraplanetary Launchpads...

Anyways... If you're looking for something interesting to attempt, check out my Kerbal Skydiving Challenge. This challenge seems to be pretty tedious- I can't imagine wanting to go further than the Mun on just SRB's... Even Scott Manley used a LFO upper stage in his famous SRB-based giant that incinerated lower stages as the next level of SRB's activated...

Regards,

Northstar

[Guest]

I don't count it.

Didn't take a picture, as I though "Oh sure, I can optimise the launch curve better than that, this is only my third attempt"...

hehehe.

Never got anything better than a 75km x -10km after that, and that is something like 100-120m/s short.

Here is a typical "good" run.

final orbit 97 x 12 (48m/s short, would have been 15m/s short if my aim was better)

((running MJ on the trials, will not need it for a final run once I have times&angles all worked out))

Method is easy.. plenty SRB to get to just below terminal velocity, then triggering next set of srb with tailored thrust levels keeps me within 85%-105% of TV.

Launch at 85* to 8500m, then more-or-less follow orbital prograde for gravity turn..

Delay last firing until alt=47500, to allow burnout at 72km.(else how circularise)

You get... 50 pp

Aim using one reaction wheel, and plenty of light batteries for power.

If i don't make orbit, use maneuver node planning to see what delta-v burn *would* have made it.

This run is 62m/s short. If i handled my turn better making apo 70-72 instead of 97, would have been 15m/s

http://i.imgur.com/axG0rNH.png

http://i.imgur.com/W5ferOj.png

Still not orbital

I added suborbital score...

You get:

450!

200: Suborbital

50: Unmanned Ship.

200: Returned from Suborbital flight.

Edited June 6, 2014 by Guest

[Guest]

kbro.

UPDATE:

Here's my progress (I'm surprised I actually had open time so soon):

http://imgur.com/a/SdqIs

The random gray line is a captured asteroid.

So I went interplanetary once and missed the Mun on corrections twice. It was fixed tho.

You are good!

You get:

1000!

Munar Ship: 900

Manned Ship:100

[Guest]

This sounds AWESOME. Totally in. SAS is still fine? Can SSTO's be staged after reaching orbit?

SAS is very fine. No staging with SSTOs.

Edited June 6, 2014 by Guest

[obi_juan]

I make a design for interplanetary ship with only SRB's.

Javascript is disabled. View full album

As you can see I use Mechjeb to calculate the delta-V for the next stage, not to pilot it.

Now, after to learn on this trial voyage I will prepare another ship to reach other planet in Kerbol system.

I need a SRB between Sepratron I and RT-10 Solid Fuel Booster for small changes of delta-V.

Edited June 6, 2014 by obi_juan

[Guest]

I make a design for interplanetary ship with only SRB's.

http://imgur.com/a/lTSnW

As you can see I use Mechjeb to calculate the delta-V for the next stage, not to pilot it.

Now, after to learn on this trial voyage I will prepare another ship to reach other planet in Kerbol system.

I need a SRB between Sepratron I and RT-10 Solid Fuel Booster for small changes of delta-V.

Holy Lord!

4200!!!

800 - Orbital Ship + Return

1600 - Minmur Ship + Return.

1800 - Munar Ship + Return.

YOU ARE #1!

[problemecium]

I may do this challenge later, but for now I join the screaming mob by asserting that SSTO with SRBs is possible. I've done it. No, I didn't take a screenshot because I didn't consider it that remarkable. You just have to lower the thrust limiter and the SRB will burn for much longer.

[Whovian]

It's easy to make a single stage to Kerbin escape (though I had FAR installed) by slapping an RT-10 on the bottom of an OKTO-2 (with, possibly, fins,) so I assume an SSTO is very possible.

[HafCoJoe]

Here. I streamed my mun landing and return. I know I won't win anything, but I wanted to attempt this as it is a goal I have had in mind for a while .

Not an SSTO.

http://www.twitch.tv/avera9ejoe/b/536176305

[It'snorocketscience]

I think I see things like Jeb. As long as they are fast and fun, who needs LOX rockets? I'm going to try this challenge. I feel so Jeblike and optimistic!

[HafCoJoe]

Question. What is the difference between landing or orbiting a body in terms of score? Does the score board have a difference? because I landed mine and returned lol.

[Guest]

Question. What is the difference between landing or orbiting a body in terms of score? Does the score board have a difference? because I landed mine and returned lol.

Just added landing points.

Twice the points of the place you went If you landed there.

[HafCoJoe]

Just added landing points.

Twice the points of the place you went If you landed there.

So I went to the mun (900) with a manned vessel (100), I landed (*2), and I returned (*2) soooo 4000? Imma do this again with more twist I think .

Edited June 8, 2014 by Avera9eJoe

[Darthzeus]

Well, this would certainly be more reasonable to allow the editing of configs to enable fuel pumping of solidfuel. Basically impossible ATM because you would have to use a lander for each body, then docking back would be impossible (nigh)