Solid Rocket "SSTO" Challenge

[Klapaucius]

Everyone, this has been incredibly fun to see what is doable. Like the Orbit Boot Camp, we are learning what is possible, and I think it is arguable that solid SSTOs are viable options for certain missions. I reckon  a hybrid of mostly solid, with a bit of liquid and a Spark engine for docking (though I am sure out there somewhere is someone who has pulled it off with solids), would be much better budget-wise then mucking about with 100% liquid engines. 

I really enjoy taking one part or area and seeing what is possible.  For some reason I caught the solid bug a few months ago, and it was my solid VTOL, which I then entered into @vyznev's KSC Hover Race:

Hopefully tagging @vyznev will get an entry out of him!

 

I think you have also proven that there is no excuse for leaving your vehicle in the middle of the runway. Parking etiquette is the new normal.

I wonder just how cheap @chargan can go and I am going to need to find a new challenge for @mystifeid  and I am also eagerly awaiting @ralanboyle to earn his Plutonium.  I hope we get a few more entrants, including more novices. This is good building and flying practice. The fact that removing engines is the key to success is quite interesting and at first counterintuitive.

Edited May 9, 2020 by Klapaucius

[mystifeid]

21 minutes ago, Klapaucius said:

I wonder just how cheap @chargan can go

Threw down the gauntlet there.

Swallow Mk2 with a cost of   13241 launches into orbit from and lands, sort of, at KSC.

 

Edited May 9, 2020 by mystifeid

[AHHans]

O.K. So here is my (first?) entry, the Stonewhale (here still with the preliminary project title):

As you can see, this is not a contender for the cheapest entry, but it will carry one primary pilot and four or five - depending on whether you need a copilot on the trip back - to space.

Some shots of the round trip, the full album is available here: https://imgur.com/a/8W4Nslp
Takeoff:

Spoiler

 

Climbing:

2nd stage burn:

 

In orbit:

Spoiler

 

De-orbit engines firing:

 

Aerobraking:

Spoiler

 

On Approach to the runway:

Landed, more or less safely:

 

At the parking position:

Spoiler

I also reloaded a quicksave and tried to land it in a less conventional spot. The landing as such seemed to be doable, but except when doing a ridiculously soft touchdown the two Pollux SRBs - which are "only" surface attached with one EAS-4 strut for extra stability - came off the central Thoroughbred booster. Which then led to collisions and explosions:

 

[Klapaucius]

I also reloaded a quicksave and tried to land it in a less conventional spot. The landing as such seemed to be doable, but except when doing a ridiculously soft touchdown the two Pollux SRBs - which are "only" surface attached with one EAS-4 strut for extra stability - came off the central Thoroughbred booster. Which then led to collisions and explosions:

For some reason, surface attachement with the SRBs is really problematic.  The way to fix this is attach the wing, attach the boosters to the wing and the use the sliding tool to move things back in to the positions you wanted them originally.

See my response to @Cavscout74 on the top of page 2. 

 

Nice job: You are the first multi-Kerbal entry and get an Argon Medal to go with your Francium.

[Klapaucius]

8 hours ago, mystifeid said:

Threw down the gauntlet there.

Swallow Mk2 with a cost of   13241 launches into orbit from and lands, sort of, at KSC.

 

That is the cheapest craft overall, but it only achieved the Rubidium Medal, so it is best in class but @chargan still retains cheapest for the Francium class.

[mystifeid]

11 hours ago, Klapaucius said:

That is the cheapest craft overall

Well, that was the goal.

Finally, finally worked out how to put a Kickback into orbit. After so many attempts it feels strange now to be able to do it every time.

The "Shrike" has a launch cost of 9600 and uses 2876 units of solid fuel at a cost of 1726. By comparison the Swallow Mk2 uses 4800 units of fuel at a cost of 2940.

With a recovered cost of 7874, Shrike is the first submission to also qualify as an entry in Orbit Boot Camp.

Seen here launching into orbit from KSC and nervously landing back on the runway.

 

Edited May 10, 2020 by mystifeid

[Chequers]

 

20 hours ago, Klapaucius said:

Everyone, this has been incredibly fun to see what is doable. Like the Orbit Boot Camp, we are learning what is possible, and I think it is arguable that solid SSTOs are viable options for certain missions.

It's amazing to see how challenges can totally change the way we view things. I've always liked SRBs, and wanted to use them far longer than their usual shelf life in career games - usually after the point in which the cost savings are outweighed by the utility of liquid fuel. Most of my rocket designs still use them to give them a cheap kick-start, but I'd never thought of the application in SSTOs... 'till now. I've even adapted a few of the vessels in my standard fleet to utilise SRBs, rather than jet or liquid fuelled engines.

Like with OBC, I've learned some very valuable lessons, that make certain contracts in the Kerbin system very profitable. Thanks for setting up the challenge, @Klapaucius - I've only submitted the one craft, but I follow the thread and enjoy everyone's submissions immensely. 

28 minutes ago, mystifeid said:

With a recovered cost of 7874, Shrike is the first submission to also qualify as an entry in Orbit Boot Camp.

The OBC committee are peering into this thread with impressed expressions.

[Klapaucius]

10 minutes ago, Chequers said:

 

Thanks for setting up the challenge, @Klapaucius - I've only submitted the one craft, but I follow the thread and enjoy everyone's submissions immensely. 

The OBC committee are peering into this thread with impressed expressions.

It is the spiritual successor to yours.

40 minutes ago, mystifeid said:

Finally, finally worked out how to put a Kickback into orbit. After so many attempts it feels strange now to be able to do it every time.

The "Shrike" has a launch cost of 9600 and uses 2876 units of solid fuel at a cost of 1726. By comparison the Swallow Mk2 uses 4800 units of fuel at a cost of 2940.

With a recovered cost of 7874, Shrike is the first submission to also qualify as an entry in Orbit Boot Camp.

 

That is just awesome!

 

I was mucking around with a Kickback today as well, but then I went down the "add too much stuff" rabbit hole. I still don't have the launch profile perfected. There is a very fine line between not getting a sufficiently high enough apoapsis and then suddenly having it shoot out to 200,000+  In a regular rocket of SSTO you'd cut the engines and readjust out of the atmosphere, but that is not really an option--unless you add more engines, which is usually not beneficial.

 

I've also successfully tested a cargo carrying Clydesdale based on to orbit. Ill have to try again and actually bring up a satellite and also land a bit closer to home.  Of course, it costs a lot.  And again, I wound up with a very skewed orbit: 802,914 AP and 109,039 PE.  

 

I actually landed at night, but we warped to morning for photos.

[mystifeid]

1 hour ago, Klapaucius said:

I was mucking around with a Kickback today as well, but then I went down the "add too much stuff" rabbit hole. I still don't have the launch profile perfected.

I adjusted the COL so that when the Kickback flamed out, it exactly lined up with the COM so that SAS wasn't creating drag with pitch trim during the fastest part of the climb and the coast to the Shrimp burn. Or that was the theory.

Ascent profile:

Initial climb at about 28° with SAS stability hold then switch to prograde hold at 6800m. The Kickback puts the Ap at about 55km and the Pe at about -300km. Coast to around 11km below the Ap (variable depending on Ap) then burn the Shrimps which puts the Ap above 70km and the Pe to around -90km. Around 400m below the Ap use the Mites. Deorbit with Sepratrons.

The standard canards were giving me liftoff from the runway at 150m/s. Mass on launch was 27.96 tons.

Most importantly, I set the thrust limiter on the Kickback to 67%. (The Pollux in the Swallows had the thrust limiter set to 50%)

Mainly I experimented with initial climb angle, prograde hold altitude and the thrust limiter. I kept getting 70/55 so I knew it was probably possible. If the Kickback didn't get the Pe to -310km or better, I knew I was doomed to another failure.

I still have the Mk1 monopropellant. Maybe if I ditch that - I think it weighs 40kg (and costs 12) - I can add another couple of Sepratrons and taxi under that R&D bridge!

Also it may turn out to be possible to remove fuel from one or more of those rockets for an even cheaper craft.

1 hour ago, Klapaucius said:

I actually landed at night, but we warped to morning for photos.

You must have come in pretty fast from an 800km AP and that's a big ship to be landing on bumpy ground, at night.

 

Edited May 10, 2020 by mystifeid

[Klapaucius]

1 hour ago, mystifeid said:

You must have come in pretty fast from an 800km AP and that's a big ship to be landing on bumpy ground, at night.

 

I just cranked up Planetshine. In real life folks have infrared and radar so it is not like it is something way out of the ordinary, and I just find the pitch black annoying when trying to land.

I'm pretty good at landing on bumpy ground--I've had lots of practice since I am not very good at hitting the runway!

I have also been using thrust limitation, but finding the magic recipe is elusive and changes for every craft.

Edited May 10, 2020 by Klapaucius

[bayesian_acolyte]

I was hoping to have the first kickback entry, but Mystified beat me to the punch while my video was converting to fast motion. I'll settle for cheapest (for now). 

Introducing the Steely Glint at 8151 initial cost:

 

 

Edited May 10, 2020 by bayesian_acolyte

[AHHans]

14 hours ago, Klapaucius said:

For some reason, surface attachement with the SRBs is really problematic.  The way to fix this is attach the wing, attach the boosters to the wing and the use the sliding tool to move things back in to the positions you wanted them originally.

Yes, I had also seen the discussion earlier in this thread. But my earlier landings wen well and I added a strut for extra strength, so I thought it would be fine. My original trip was all done in one go without loading a (quick-)save, the second attempt was after loading a savefile. And my original landings weren't all that soft, so I think the act of saving and loading might also compromise the strength...

Anyhow, I improved my design (with an extra, empty fuel tank ) and can now present you the Stonewhale 2f:

As you can see this is the cargo version. It does have space for a mission specialist in the cockpit, but AHTech Industries suggests that you contact your local spacefarers union representative before leaving them in orbit.

The full documentation can be found on here: https://imgur.com/a/A5bTtb9
Some selected highlights are:

Spoiler

Orbit insertion:

Deploying the cargo:

 

Spoiler

 

View from the deployed satellite:

De-orbit burn. Due to the high orbit two of the taxi engines needed to be used in order to reach the KSC.

 

The orbits during aerobraking:

"Jeb!?! The runway in in the other direction!"

"Jeb!!! That is not the runway in front of us!"

"Meh! Who needs runways?"

Spoiler

And, yes, two taxi engines were enough to get us to the parking position at the research labs.

P.S. Do I get my Caesium-137 medal now?

Edited May 10, 2020 by AHHans

[mystifeid]

1 minute ago, bayesian_acolyte said:

Introducing the Steely Glint at 8151 initial cost

Awesome. I'm about to get busy for a while and I'm pretty SSTO'd out anyway but maybe @Klapauciuscan rustle you up some competition. I pity them.

[Klapaucius]

I was all set to be the first with a satellite and got beat to the board!  

This was a frustrating launch. I did a quicksave which I made use of after I stupidly hit the spacebar to stage rather than my action group to deploy my satellite. No matter, we got in orbit, deployed the mini satellite (that I had originally built for a lighter craft I abandoned).  I misjudged the deorbit burn--I'm only just getting this hang of how to land at the KSC from orbit) but it would not have mattered anyway. My front gear is attached to the cargo bay, and the gear refused to deploy--arghhhh!!!! I hate that feature!  If I had been thinking I would have opened the bay, but I was pretty close to the ground anyway at that point.  Sigh...

Anyway, a Sodium for Kuragina (named after a character in War & Peace).

 

28 minutes ago, mystifeid said:

Awesome. I'm about to get busy for a while and I'm pretty SSTO'd out anyway but maybe @Klapauciuscan rustle you up some competition. I pity them.

Thank you for your commitment to the cause!  It's been fun and you have raised the bar high.

[mystifeid]

2 minutes ago, Klapaucius said:

Thank you for your commitment to the cause!  It's been fun and you have raised the bar high.

And I got an atom of Organesson !!

[AHHans]

On 5/6/2020 at 4:55 AM, Klapaucius said:

Gets a slightly lower grade Cesium 137 Isotope for not keeping off the grass.

Yessss!!!

1 hour ago, Klapaucius said:

I was all set to be the first with a satellite and got beat to the board!  

Well, I did that trip already yesterday and when I saw that you were also working on a cargo version I interrupted my weekend chores(*) to hack together my report. (No, I'm totally not competitive.)

Quote

My front gear is attached to the cargo bay, and the gear refused to deploy--arghhhh!!!!

Well, you did manage to get your Kerbals safely back to the ground! That does have to count for something, doesn't it?

Thanks for starting this fun and interesting challenge. Although I think I'll stick to liquid-fueled SSTO spaceplanes for my career games, they are just more capable and easier to fly.

P.S. The price for my craft can be seen in the screenshots from the editor. The Stonewhale costs 50,707 and the Stonewhale 2f (including the satellite) costs 52,903 (Without the satellite and decoupler it is 47,113  but it would be unstable to fly until the Thoroughbred booster has burned out because the CoM would be too far back.)
P.P.S. (*) Yes, I do some of them on the Sunday. In contrast to what some people (here) think that's not actually illegal, even in Germany.

Edited May 10, 2020 by AHHans

[Klapaucius]

I've tried some Shimp only variants. Gettting a Kerbal up, at least at this stage in development seemed a bridge too far, so I opted for some automation. That does not get me anything, but it is an interesting exercise. Trying to get the delta V numbers up is an exercise in diminishing returns. I have not managed it yet, but at least got the ship (the unKerbaled one) up over 85000. 

 

[AHHans]

Just now, Klapaucius said:

Trying to get the delta V numbers up is an exercise in diminishing returns.

Ah, yes, I also noticed that. The thing is that the SRBs have a fixed fuel to dry-mass ratio. So once the total mass of your craft is dominated by SRBs then adding more of the same SRBs will not noticeably increase your dV.

[Klapaucius]

1 minute ago, AHHans said:

Ah, yes, I also noticed that. The thing is that the SRBs have a fixed fuel to dry-mass ratio. So once the total mass of your craft is dominated by SRBs then adding more of the same SRBs will not noticeably increase your dV.

I put two Hammers on an earlier rocket and my delta V decreased!

[AHHans]

14 minutes ago, Klapaucius said:

I put two Hammers on an earlier rocket and my delta V decreased!

Jupp.

I just tested, one OKTO2 plus one (many for the small, lightwheigt ones) SRB gives the following vacuum dV:

• 9*Flea: 1937 m/s
• 9xHammer: 2971 m/s
• 17xMite: 3264 m/s
• 1xThumper: 3312 m/s
• 9xShrimp: 3544 m/s
• 1xKickbac: 3596 m/s
• 1xPollux: 4100 m/s
• 1xThoroughbred: 4381 m/s
• 1xClydesdale: 4433 m/s

So, yes, bigger is better. And you won't get much farther than Kerbin orbit with SRB "SSTOs". But it also says that a Shrimp only SSTO would in theory be possible. (Maybe not as a horizontal take-off.)

Edited May 10, 2020 by AHHans

[Klapaucius]

39 minutes ago, AHHans said:

P.S. The price for my craft can be seen in the screenshots from the editor. The Stonewhale costs 50,707 and the Stonewhale 2f (including the satellite) costs 52,903 (Without the satellite and decoupler it is 47,113  

We won't count the satellite since that is cargo and is meant to be deployed. 

[sevenperforce]

The vacuum isp here is a huge determiner due to the fixed mass fraction.

[ralanboyle]

Alright, I 'd like to add Argon, Krypton and Radon medals. Still working on the Plutonium, not sure if I'll pull it off. I made a Solid SSTO that carries a Solid SSTO to orbit as cargo. It was going to be a whole cool thing but it breaks apart constantly due to aero/g forces and kraken.  So, for now, this. 

 

[Klapaucius]

6 hours ago, ralanboyle said:

Alright, I 'd like to add Argon, Krypton and Radon medals. Still working on the Plutonium, not sure if I'll pull it off. I made a Solid SSTO that carries a Solid SSTO to orbit as cargo. It was going to be a whole cool thing but it breaks apart constantly due to aero/g forces and kraken.  So, for now, this. 

 

You now have Argon and Krypton. To get Radon you have to take off from the Island Airfield as well --that 90 degree turn after turning on the engines full is fun--but you can do that on the next mission. There is no rule that states the takeoff and landing have to be on the same mission.

[mystifeid]

To claim the last two endorsements - (Is there an endorsement for having all endorsements?) - here is SRB Cargo taking 7 Kerbals and a relay sat into orbit before landing and parking in front of the SPH. Cost without the sat is 32120.