Caveman Tech SSTO Challenge

[Andetch]

Right, I was thinking about this for a while. I have been playing with low-tech craft for a little while. It's a challenge as there is usually a higher tech part you need.

I have recently made two CaveTech SSTO craft, one horizontal launched spaceplane style, and one vertical launched that leaves a capsule in LKO, with the booster being put on atmospheric capture and returned to Kerbin's surface for recovery and potential re-use (but as no probe core the game sees it as junk, sadly). 

Now, I've tried to repeat the achievement using a different combination of parts and despite repeated attempts I have failed miserably. Every. Damned. Time. And I am sure it isn't pilot error, as I can put the original CaveTech SSTO up there every time now. I figured getting more minds involved would help, see if I have stumbled upon a holy grail here or what?

So...... (explanation of why I am posting the challenge over!).....

The Prize

Mainly kudos and bragging rights. I could make a simple badge if someone does it! EDIT: I have made a simple badge as a few people have done it.

As for scoring it is all subjective. 

The Challenge!

CaveTech Only. My difficulty was set to normal - easy would be too easy, but any harder than normal and you're insane!

Cheat your science points up if you want.

Build a SSTO, either spaceplane or vertical launched style. Make it different to my examples if you can - I appreciate parts are limited but I am not looking for clones of what I already have here. 

I am mainly interested in you achieving SSTO, but you should also have a plan on how to return to Kerbin's surface.

Stock preferred (visual and information mods okay). Making history is also fine. 

Rules quoted from The Caveman Challenge;

Facility upgrades are forbidden.

Terrible runway and launchpad.

Part count of thirty and vehicle mass limit of 18.0 tons.

No fancy patched conics, no maneuver nodes and no Deep Space Network.

Abhorrent fear of technology as primitive as can be.

No mods that alter game play (mods used for filming, radio chatter, etc. are fine)

No cheat menus or any other shenanigans

No kraken/ladder drives or similar contraptions

Proof of Concept

My videos below to show it is possible. Feel free to download and reverse engineer my craft (available via the KerbalX link in signature) to assist you, but as i said, you gotta try and make them different!!!!!!

Good luck engineer pilots, and thank you for helping satisfy my curiosity!

 

 

Edited June 1, 2018 by Andetch
Formatting

[Kergarin]

Here is my SSTO rocket which only needs unlocking of one single tech node for just 5 Science Points. 

Also returns to surface 100% intact and reusable.

I would love to build a spaceplane, but it is just to hot here to start a computer 

Edited May 28, 2018 by Kergarin

[Andetch]

@Kergarin thanks for that. I wouldn't have even considered the concept, so that's exactly the sort of thing I'm looking for! You could have had a fair bit of dv left in lko also, had you not raised the AP so high, so kudos!

Now I gotta play with that concept. Hard career mode just got easier!

[Andetch]

21 hours ago, Kergarin said:

I would love to build a spaceplane, but it is just to hot here to start a computer 

So, I've recreated various iterations of this design (like replacing the 14 fuel tanks with the same amount of fuel in less tanks, and putting a reliant in for the swivel) and yes, it is interesting. Still, I can't seem to put wings on it and make a spaceplane style SSTO style from it. 

Any other takers for a spaceplane style caveman SSTO?

[Gordon Fecyk]

After all the practice I've had on Eve, this turned to be a lot easier back on Kerbin. Here's a Caveman SSTO entry.

I only had to cheat the science to avoid career grinding per Andetch's challenge rules. Everything else is using Level 1 buildings and Tier 5 technology, which gives me the J-33 Wheesley jet engine and small retractable landing gear.

One caveat: In order to cram enough fuel for a safe return trip, wing strength was reduced as is available in Ferram Aerospace. The mass of this craft fully fueled was 17.999 tonnes and that's after reducing most wings to 40% of their stock mass. I'll leave it up to Andetch to determine if this is a rule violation or not.

[Update] I had to modify the craft to fix a bad centre of mass problem. I uploaded an updated craft to Kerbal X and am publishing a video demonstration shortly right now.

 

Edited May 30, 2018 by Gordon Fecyk
Added video

[ManEatingApe]

This simple spaceplane gets the job done...however as there's only 700 m/s dV left once in LKO I'm not sure what exactly the job is 

Tech tree requirements are sparse

In orbit

Aerobrakes nicely

Coming in for KSC landing

 

Remaining photos

Edited May 29, 2018 by ManEatingApe

[Gordon Fecyk]

There's also a Turbo Pumped low tech special that can do a Mun flyby. How he got 650 m/s out of the Junos is beyond me.

 

 

[ManEatingApe]

17 minutes ago, Gordon Fecyk said:

There's also a Turbo Pumped low tech special that can do a Mun flyby. How he got 650 m/s out of the Junos is beyond me.

Awesome, what a great craft!

[Andetch]

14 hours ago, Gordon Fecyk said:

After all the practice I've had on Eve, this turned to be a lot easier back on Kerbin. Here's a Caveman SSTO entry.

I only had to cheat the science to avoid career grinding per Andetch's challenge rules. Everything else is using Level 1 buildings and Tier 5 technology, which gives me the J-33 Wheesley jet engine and small retractable landing gear.

I like your method of cheating. Taught me a lot - I have generally tried to limit my use of the F12 menu and don't really know how to use it and usually resort to throwing a capsule around each planet and getting crew reports! 

14 hours ago, Gordon Fecyk said:

One caveat: In order to cram enough fuel for a safe return trip, wing strength was reduced as is available in Ferram Aerospace. The mass of this craft fully fueled was 17.999 tonnes and that's after reducing most wings to 40% of their stock mass. I'll leave it up to Andetch to determine if this is a rule violation or not.

[Update] I had to modify the craft to fix a bad centre of mass problem. I uploaded an updated craft to Kerbal X and am publishing a video demonstration shortly right now.

I tried using FAR once, and couldn't work out how to get the flaps/control surfaces to do what I wanted them to do (but my flying car still seemed to work, just not quite as well or easy to control) and haven't explored it since. I really should get back around to it as I know it is a very good mod. Someone always comes up with a FAR request on every challenge, so I should have foreseen it too! 

Now, as I am sure you gathered from reading (did you read?) my rant at the beginning, this was more about showing me new ways to achieve the Caveman SSTO, specifically a Spaceplane. I am assuming that by reducing wing strength, it reduces the mass of the wing allowing the tanks to be filled to the brim? 

As far as rule violations go, I don't see anything wrong with your entry and video - I really liked it and learned a lot from it, so thank you for the lesson. I have more ideas to play around with now. (My SSTO didn't even have an air-breathing stage as I viewed carrying the engine as dead weight, and used the 7.5 monoprop in the cockpit as it's fuel to de-orbit, so you really smashed my initial thoughts there. Although, I wonder how much FAR affected it/made it easier? (if at all?)) 

So definitely a big thumbs up and a pass from me! 
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13 hours ago, ManEatingApe said:

This simple spaceplane gets the job done...however as there's only 700 m/s dV left once in LKO I'm not sure what exactly the job is 

700 m/s of dV is quite a bit (I believe IRL the Space Shuttle operated with around 300 m/s of dV once reaching LEO, needing to save 150 m/s for it to set up it's landing) to have left over in LKO as far as I am concerned. Especially for a Caveman SSTO Spaceplane. Ugly looking brute, very neanderthal. I like it. Again, gives me plenty of food for thought, and does teach me a lot. 

So without question a thumbs up and a pass from me! 

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I think my problem is, as you will see from my two videos is that (and this is not necessarily a bad thing) that once I have found something that works I find it hard to "think outside the box" and variate away from the idea and get something else to do the same job differently.This even goes for the way I re-enter and land back at KSC - @Gordon Fecyk does it completely differently to me (he kept a PP at 25KM where as I always try to set a collision course to somewhere between KSC and "Korea"), yet gets the same result! 

So, once again, thanks to both of you for taking the time and effort to do this and teach me some new ways of doing a low tech space plane SSTO!

3 hours ago, Gordon Fecyk said:

There's also a Turbo Pumped low tech special that can do a Mun flyby. How he got 650 m/s out of the Junos is beyond me

That guy takes the liquid! Lol! So I am definitely not special with my CaveTech SSTO then  

Meh, I am fairly confident mine handles better though! And I was pleased that the concept of sending down something that the game identifies as junk, but with an already triggered parachute worked in the vertical rocket! Back to the drawing board again, with a mind full of new ideas! 

[Gordon Fecyk]

4 hours ago, Andetch said:

Although, I wonder how much FAR affected it/made it easier? (if at all?)) 

If you consider a reworked drag model 'easier,' then I suppose it's easier. But then you have to overcome all of the other headaches that come with it. You are literally learning how to fly again.

That 25 km PE? Here's a low tech space plane that uses the 25 km PE above KSC, and here's the same space plane using a zero PE east of KSC. In the latter example, I lost control once the craft got too low in the air, and couldn't regain it until I shed enough speed. In the former, I shed speed gradually until low enough to ignite the jets, all the while maintaining control.

If you can master the FAR aerodynamics though, you can wring a little more delta-v out of your craft.

Thanks for the review and encouragement. Pushing boundaries is what the caveman challenges are all about.

[Andetch]

16 minutes ago, Gordon Fecyk said:

If you consider a reworked drag model 'easier,' then I suppose it's easier. But then you have to overcome all of the other headaches that come with it. You are literally learning how to fly again.

That 25 km PE? Here's a low tech space plane that uses the 25 km PE above KSC, and here's the same space plane using a zero PE east of KSC. In the latter example, I lost control once the craft got too low in the air, and couldn't regain it until I shed enough speed. In the former, I shed speed gradually until low enough to ignite the jets, all the while maintaining control.

If you can master the FAR aerodynamics though, you can wring a little more delta-v out of your craft.

Thanks for the review and encouragement. Pushing boundaries is what the caveman challenges are all about.

By the FAR/easier comments I am talking about the way shape of craft affects drag/lift. I had to make mine long and thin or drag would prevent it getting there (same amount of fuel, thrust and parts but configured differently won't make it hence why it used the engines it does). Also you will notice in my SSTO (I think the same as yours, but not to the same degree) I have to play with throttle a lot and the pitch. It really was a "goldilocks" formula.... rotate at the right speed (the craft can lift off earlier, but you want to build to forward momentum, not too little, not too much), pitch up to the right angle (not too steep, not too shallow) accelerate to 200 m/s and do not exceed that speed much until you clear the soup, then allow yourself to pitch down (again, not too little, not too much - you see the theme here)....

The return in mine is so easy though as when it is that light it gets so much lift you can glide for ages and ages. 

[Muetdhiver]

Hell, that's really lovely stuff.

I have to try to build one now. Damn you all XD.

Btw, all of this made me think about a staged caveman spaceplane where the wings and junos are ditched in flight, with a terrier setup with drop tanks in the front part of the plane. I Wonder what kind of mass fraction can be put in LKO with such a scheme. Junos are amazing engine as they can reach Mach2, unlike later (and bigger) engines of it's type.

Caveman rockets seems to top out at 3.5 tons of payload for me, so if there is a way to push this up this would be really neat.

[Andetch]

13 hours ago, Muetdhiver said:

Btw, all of this made me think about a staged caveman spaceplane where the wings and junos are ditched in flight, with a terrier setup with drop tanks in the front part of the plane.

Do it! You've said it now, you have to! (And look, I'm using bold font so that makes it even harder to say "no"). I scrapped this idea after toying about with it because I figured that the weight of the decouplers needed was waste and opted for fuel instead. Heck, I even scrapped the idea of an aerial because of drag/weight concerns and opted to keep the single battery instead. 

13 hours ago, Muetdhiver said:

Caveman rockets seems to top out at 3.5 tons of payload for me, so if there is a way to push this up this would be really neat.

I wasn't so interested in payload to LKO on this challenge, more that it is SSTO... However, seeing as you mention it have you seen this thread by Slashy? Cunjo Carl's Huck leads the way at over 4T into LKO with a similar concept to what you have mentioned above!

 

Edited May 31, 2018 by Andetch

[Muetdhiver]

As I'm terrible at planes in KSP, so It took me an inordinate number of tries.

In the end I went for a single terrier and 4 junos with a design mimicking what Turbo Pumped did. 650 m/s on Junos is indeed possible.

I was skeptical at first, but it the craft is well balanced and you keep altitude low, it works ! (It takes a long time to reach the speed though). With such speed you get to 10km with 500 m/s which is really neat. The the terrier kicks in and voilà ! Aerobraking was done with the trusted helicopter method, otherwise all the intakes went poof. It was quite fun, but I still suck at SSTO's. I lost the terrier at landing, and I'm not good enough to keep back to the space center.

Spoiler

 

Edited May 31, 2018 by Muetdhiver

[Andetch]

@ManEatingApe just out of interest - what was the fuel load in your design like? Did you fill both LF and OX up or did you drain some OX to allow for what the air breather drank? 

@Muetdhiver Well done on that run! Again completely different to my design... Making me feel like this could turn into a K-Prize Caveman style challenge as there clearly are many ways to do this. You're good enough to make a Caveman Tech SSTO Spaceplane which is something few have done, so feel proud of your achievement!

1 hour ago, Muetdhiver said:

and I'm not good enough to keep back to the space center.

Have you watched the videos from @Gordon Fecyk's entry (incidentally, I really liked the editing on the rescue mission, and the visual mods you use are very nice.... puts my videos to shame!)? They're really good to show how to approach a KSC landing. It does take some practice, but just like maing an orbital RV and docking once you get your head around it it becomes quite easy (can't believe how at first when I didn't understand orbital RV and docking how I used to try and build stuff that never needed to be docked, and what a game changer learning to dock was!) and it is a really satisfying feeling when you get the approach just right and nail a nice perfect landing. Even if you overshoot and have to turn around of land on the island, it's still good

Edited May 31, 2018 by Andetch

[Gordon Fecyk]

1 hour ago, Muetdhiver said:

Aerobraking was done with the trusted helicopter method, otherwise all the intakes went poof.

That's where using a higher approach might save you and your parts, to help spread the thermal load.

Even over the course of my Hosers In Space story, I found approaches with a zero PE difficult to control even if parts didn't explode, and later attempts with a 25 km PE were far more controllable. Doing a gradual re-entry will save your parts and help you maintain control. Even my entry had two small intakes that survived handily.

[Andetch]

That makes a lot of sense..... Although it is thoroughly un-Andetch. We like to live on the extremes  and have never made things easy for oneself. 

I have a SSTO that without the weight of the 1000KN engine on the back is just shy of 14T.... Makes it a stand-up guy to fly, but when that baby ignites it makes all those lost kerbals worth it! Although again, as I have advised @Muetdhiver KSP is all about learning new techniques and then looking back and going "duh, why was I doing it that stoopid way" so I will probably start exploring the gentle re-entry approach. 

[ManEatingApe]

4 hours ago, Andetch said:

@ManEatingApe just out of interest - what was the fuel load in your design like? Did you fill both LF and OX up or did you drain some OX to allow for what the air breather drank?

The FL-T100 tank just in front of the Wheesley had all oxidiser removed.

Inspired by the Juno flat ascent ascent profile, I tweaked the craft by adding some incidence to the wings and flying practically flat until 9,000 metres altitude. After lighting the Terriers the profile was also kept very flat (no higher than 15° attitude)

This got much better results, just under 900 m/s dV in LKO. Enough to reach past the Mun and there's some unbalanced OX left over, so room for improvement. I might play around to see what further tweaks can be made.

I'm impressed by the sheer permutations of design possible even with Cave tech:

• 1 x Swivel
• 2 x Thud
• 2 x Wheesley + 1 x Reliant
• 1 x Wheesley + 2 x Terrier
• 4 x Juno + 1 x Terrier

The only promising engine left out is the Spark, they pack quite a punch for their size!

Edited May 31, 2018 by ManEatingApe

[Muetdhiver]

The spark is an amazing engine. The only problem with it is that like the Juno, one generally need several of them. Which is often a problem with the 30 parts limits.

One terrier and two sparks with a bit of Oscar B clipping is really nice to get a 100 kn engine with good vacuum isp.

An other fantastic use of the spark is as verniers engine for a reliant. On an 18t rocket this push twr to 1.3 which is full of win. 

Also epic twr means it can beat the terrier in some cases as a vacuum engine when dry mass is low, despite worse isp. 

25km pe for spaceplane re-entry : thanks for the tip. Nearly got to the ksc. 

[Andetch]

Must say I am really impressed by the Cave Tech Spaceplane Mun flybys. Not something I thought that probable initially. As you will see from my offerings the room for error is so fine, the leftover dV in orbit is not much at all. Although, if I am right (correct me if I am not) these mun flyby's you circularize while below the Karman line (70km)? So launch has to be perfectly timed.

[Andetch]

@Gordon Fecyk @ManEatingApe @Muetdhiver Seeing as you've done a great job, and really helped me answer KSP questions I have used my rudimentary, neanderthal image creation skills (with the assistance of logomakr.com - the mention is part of the terms of the free to use licence) to fashion a badge of some sorts. I am pleased to present you all with your Caveman Tech Spaceplane Builder badge! (Copy it from here, or from the OP).

 

 

[ManEatingApe]

3 hours ago, Andetch said:

Must say I am really impressed by the Cave Tech Spaceplane Mun flybys. Not something I thought that probable initially. As you will see from my offerings the room for error is so fine, the leftover dV in orbit is not much at all.

If you like the Mun flybys, you'll appreciate this...

Tweaked the design by removing the rear FT-100 and replacing it with 2 wing tanks, shrinking the wings from type B to C to compensate for the extra tank mass.

Result: 1000 m/s dV in LKO - nearly enough to go reach Duna. So close!

 

3 hours ago, Andetch said:

Although, if I am right (correct me if I am not) these mun flyby's you circularize while below the Karman line (70km)? So launch has to be perfectly timed.

I circularise in LKO first, although the ascent is aggressively shallow.

 

2 hours ago, Andetch said:

...I have used my rudimentary, neanderthal image creation skills (with the assistance of logomakr.com - the mention is part of the terms of the free to use licence) to fashion a badge of some sorts. I am pleased to present you all with your Caveman Tech Spaceplane Builder badge!

Thanks for the badge, I've thoroughly enjoying this challenge!

[Muetdhiver]

Wow. 1000 m/s in LKO is more than I thought possible. Hats off.

I like the whesley + 2x terrier design a lot I must say. It seems the only way to go to 18t without using too much parts and too much dead weight. Mine did not get anywhere yet though

Is it possible to get to duna and back with a caveman SSTO ? It might be possible using a kerbin grav assist with a 1.33 or 1.5 year orbit... i.e. Launch 4 or 3 years ahead of the window and do a kerbin assist to save fuel ?

Although, without patched conics it would be a tall order. Maybe with iterative orbital corrections like to get to Eve with caveman tech. Hm. Interesting questions.

[Andetch]

51 minutes ago, Muetdhiver said:

Is it possible to get to duna and back with a caveman SSTO ? It might be possible using a kerbin grav assist with a 1.33 or 1.5 year orbit... i.e. Launch 4 or 3 years ahead of the window and do a kerbin assist to save fuel ?

Although, without patched conics it would be a tall order. Maybe with iterative orbital corrections like to get to Eve with caveman tech. Hm. Interesting questions.

If you can do a Duna flyby and return to Kerbin in a Caveman Tech Spaceplane I will dig out that old photo of my wife in a bikini before she had our child and use that for the badge 

However, I am just thinking, the small size docking ports are caveman tech. So..... I guess plotting an orbital RV and docking with the lvl1 tracking station will be a challenge in itself, so I am inclined to allow it. SSTO only means Single Stage to Orbit (implied LKO so refueling in LKO still means it meets SSTO requirements), so I am leaning towards saying if you can do it then go ahead.... but it would be far more impressive and warrant me going back and putting a gold background into the badge if you can squeeze those extra m/s dV @ManEatingApe to get the flyby and return as a SSTDFB/SSTDO. Remember (if you haven't already) that 7.5 monoprop and a single thruster goes a long way with an empty craft as is shown in my research. If that helps at all.....

[Muetdhiver]

Actually Rendez-Vous and docking is not that hard in Caveman once you figure a few tricks out.

1. Start with launch with the target about 15-20° before KSC.
2. Cancel out difference in inclination if any.
3. Match orbits but keep AP slightly above. Wait. Wait. Reduce AP a bit. Wait some more. Wait. Once at max zoom the target and vessel appear to be close by (i.e. 5mm), it means that you are in visual range.
4. Point ahead of target apparent motion and burn. Repeat till close enough to select docking port as target. Proceed as usual.

But... Cavemans can't transfer fuel with L1 facilities. I know, it's really anoying and complicates missions.

For a Caveman Duna landing you have to dock the ship with a fuel pod. Getting the duna encounter is the hard part, not the assembly. (Return is easier because Kerbin has zero excentricity). And Ike is a terrifying piece of rock for Cavemans. Unless one ditches the refueling SSTO as a drop tank...

I know for a fact that one can get to Duna with T2 tech (reliant only) and that 2100 d/v is enough for a return trip with Duna orbit, doable in a single Caveman launch. The way I see it, a flyby should be possible with a kerbin grav assist : theorectical Dv for this is 1050 m/s, plus return correction and correction burn for the duna gravit assist/brake from the flyby. It can probably be done with say 1400 to 1500 m/s. If we grav assist for 300 m/s (?) then it does look doable on paper. Maybe

The big question is how to get a grav assist right without patched conics.

Edited June 1, 2018 by Muetdhiver