The Reusable Launch Platform Challenge

[Northstar1989]

9.81 * 355 * ln(816.3/220.7) ≈ 4555.

The initial Isp of the rocket is around 307 s. By the time the boosters burn out, it's around 365 s, and the core still has over 40% fuel left with Isp 380 s. Therefore 355 s should be pretty good estimate for the average Isp.

Which is exactly what my math looked like. Actually, my calculation was a little more generous with ISP, and calculated out to 4600-4700 Delta-V.

4500 Delta-V is known to be the bare minimum Delta-V to get a rocket to obit from Kerbin without making use of aerodynamic surfaces, and assumes a 100% efficient fuel-optimal ascent. So a rocket with 4555 or 4600 Delta-V wouldn't have left you with enough fuel to de-orbit and land with 50 Delta-V to spare...

Is there something I'm missing here? The STS parts are known to have exceptionally have ISP for their thrust and weight, but you would have needed an average ISP of roughly 374 (giving a Delta-V of 4800) to get the kind of performance you claimed here, and you said yourself your ISP maxed out at 380 and was only 307 on the launchpad...

EDIT: I see you relied heavily on parachutes during your descent, which helps a lot with Delta-V expenditures. But it looks like you made a targeted landing near the KSC, which takes a LOT more than the 24 Delta-V you are claiming to have spent getting down from orbit (your screenshot shows you had 74 Delta-V in orbit, and you yourself said you had 50 for touchdown- was that atmospheric or vacuum?). Just going from your screenshots alone, I'm not seeing how it was even possible for you to touchdown there without extreme luck or a *LOT* of F5/F9...

Edit #2: OK, never mind about the descent. I see you had 143 Delta-V after detachment of the payload- which would have been enough for de-orbiting (that assumes you spent approx. 93 Delta-V on de-orbit, which is rather precise but certainly possible). How did you get to orbit though? The numbers don't add up- you would have had to spend only 4481 Delta-V to get to a 100x100 km orbit, and the BEST ascents are known to cost 4500 m/s to get to a 70x70 km orbit. The only way I can see it even being possible is with a super-precise autopilot...

According to the Wiki:

"Doing so with a fuel-optimal ascent requires a delta-v of ≈4500 m/s"

Regards,

Northstar

Edited June 8, 2014 by Northstar1989

[Jouni]

Edit #2: OK, never mind about the descent. I see you had 143 Delta-V after detachment of the payload- which would have been enough for de-orbiting (that assumes you spent approx. 93 Delta-V on de-orbit, which is rather precise but certainly possible). How did you get to orbit though? The numbers don't add up- you would have had to spend only 4481 Delta-V to get to a 100x100 km orbit, and the BEST ascents are known to cost 4500 m/s to get to a 70x70 km orbit.

I probably used something like 4600 m/s for the ascent, because it was a pretty bad one. In my earlier attempt, I had about 200 m/s left after detaching the payload, but it was a practice run, so I didn't take any screenshots.

[Northstar1989]

I probably used something like 4600 m/s for the ascent, because it was a pretty bad one. In my earlier attempt, I had about 200 m/s left after detaching the payload, but it was a practice run, so I didn't take any screenshots.

That's.... impossible without some kind of source of lift. The best ascents anyone has ever managed were 4450 m/s to orbit!

The best I can figure is that we might have underestimated your total Delta-V... More screenshots of the launch and ascent would have been helpful for that...

Anyways, I'll stick you on the Successful Missions List, but I've definitely got my reservations about it- like I said, your payload mass and fuel fraction figures seem a little iffy...

Do you have any information on your TWR at liftoff, by the way? Was your lifter manned? (I didn't see a command pod) And did you quicksave? I'm trying to figure out what distinctions you qualified for besides "Motherland Lifter"

Regards,

Northstar

Edited June 8, 2014 by Northstar1989

[Northstar1989]

I got a shuttle that can meet this challenge with minimal modifications. However, it will be next week before I can get it online since I'll out of town for a week. But once I get back I'll be sure to post it.

Go for it! I look forward to your entry!

Regards,

Northstar

[Jouni]

The best I can figure is that we might have underestimated your total Delta-V... More screenshots of the launch and ascent would have been helpful for that...

The rocket has 3941 m/s atmospheric and 4807 m/s vacuum delta-v. If we use 70% vacuum / 30% atmospheric Isp while the boosters are burning, and vacuum values afterwards, the total becomes 4653 m/s, which seems quite reasonable. I had 73 m/s left after the documented ascent, and a bit over 100 m/s after the practice run, so the numbers seem to make sense.

Do you have any information on your TWR at liftoff, by the way? Was your lifter manned? (I didn't see a command pod) And did you quicksave? I'm trying to figure out what distinctions you qualified for besides "Motherland Lifter"

It doesn't qualify for anything other than "Motherland Lifter". Initial TWR was 1.31, and the rocket would have needed two more S3-14400 fuel tanks to get the TWR below 1.1. I used quicksaves quite a lot to get the landing right.

[Spartwo]

I'm currently editing this to include my entry but I'm wondering why there is no powered landing qualification?

EDIT:

Due to the limitations of KSP I had to do it in 2 separate flights the first landing the lower stage and the second for everything else (although there is a mod which would allow me to do it in 1)

Liftoff

The lower stage goes to 10km detaches and uses the remaining fuel to land.

*one relaunch later*

The second stage brings the capsule into a 75x75km orbit and brings itself down.

The capsule then deorbits and lands using rockets or engines.

The second stage was the one used but the first one hiding in shame behind the big tank is just for effect.

Edited June 9, 2014 by Spartwo

[Northstar1989]

I'm currently editing this to include my entry but I'm wondering why there is no powered landing qualification?

Do you mean you're curious why there's no Distinction for a powered touchdown without parachutes?

Because I felt that would be a little too hard for most players not using MechJeb- I didn't want players to feel pressured to use MechJeb to "compete". Kudos for attempting it without parachutes though- even *I* use small parachutes on my Space-X style rockets that, though not nearly large enough to land their respective stages, help keep the top end upright through their torque... (I used to do it without parachutes, but I found that forced me to rely heavily on MechJeb for the landings- which I didn't like)

EDIT:

Due to the limitations of KSP I had to do it in 2 separate flights the first landing the lower stage and the second for everything else (although there is a mod which would allow me to do it in 1)

Liftoff

http://i.imgur.com/AWehe2d.png

The lower stage goes to 10km detaches and uses the remaining fuel to land.

http://i.imgur.com/SB6SuAR.png

http://i.imgur.com/KFvD4c0.png

*one relaunch later*

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

The second stage brings the capsule into a 75x75km orbit and brings itself down.

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

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

The capsule then deorbits and lands using rockets or engines.

http://i.imgur.com/V4eXaJd.png

http://i.imgur.com/o7i7u0s.png

http://i.imgur.com/rw1Vf6g.png

The second stage was the one used but the first one hiding in shame behind the big tank is just for effect.

Unfortunately, you need to do both stages in the same launch. I thought it was implied in the statement that all stages had to be recovered- technically, your upper stage is lost in the first launch, and your lower stage in the second launch.

This also ensures that there aren't any problems in your ascent profile that might not become apparent in what are technically two separate launches (such as the upper stage not having enough Delta-V to get to orbit if the lower stage saves enough fuel to safely touch down again- note that I didn't even see how much fuel was left in the lower stage at separation on the 2nd launch...)

Further, this forces players to make use of a little more realistic rockets- because Kerbin is such a small planet, it takes very little Delta-V to get to orbit compared to real life. But because you need the entire rocket to clear the atmosphere before your lower stage detaches (or at least burn to a sufficiently high apoapsis that you can circularize the upper stage before the lower stage falls below 23 km), it forces the player to use rockets with lower stages that are heavier and have more realistic Delta-V values...

I'm sorry- in theory your entry would be fine (though it's less useful in-game: any rocket that works Space-X style without stage-loss on Kerbin would also be useful for reusable missions on Duna, for instance). But it doesn't meet the qualifications for the Challenge. I suggest trying it again with a heavier lower stage (just stack some more fuel tanks onto it, basically) so you can recover both stages in a single launch.

Regards,

Northstar

P.S. Add some drop-tanks (detachable fuel tanks that feed into your core stage with fuel lines) to your lower stage to increase performance a bit. If they detach and land again before your rocket reaches 2.3 km (at is likely with anything meeting "Slow Climber"), then it's possible to incorporate 2 staging events instead of 1 into your rocket... This works best with giant rockets with large drop tanks though, as even the smallest decoupler has a certain amount of mass that you have to additionally lift, and parachutes only get so small relative to the drop tank...

Edited June 9, 2014 by Northstar1989

[Northstar1989]

The rocket has 3941 m/s atmospheric and 4807 m/s vacuum delta-v. If we use 70% vacuum / 30% atmospheric Isp while the boosters are burning, and vacuum values afterwards, the total becomes 4653 m/s, which seems quite reasonable. I had 73 m/s left after the documented ascent, and a bit over 100 m/s after the practice run, so the numbers seem to make sense.

It doesn't qualify for anything other than "Motherland Lifter". Initial TWR was 1.31, and the rocket would have needed two more S3-14400 fuel tanks to get the TWR below 1.1. I used quicksaves quite a lot to get the landing right.

Alright, well nice job! It might have raised my eyebrows a bit less (and would have gotten you the "Slow Climber" Distinction as well as a larger payload to orbit in a single launch- the latter being useful if you're working this mission into your main save) if you had stacked on those two additional fuel tanks though...

I guess I just always raise my eyebrows at VTOL rocket SSTO's because they're not really very feasible in the real world, where Delta-V to orbit is MUCH higher- at around 9-10 km/s... (designs with staging, like the Space-X Falcon 9r, work much better) Although, there *WAS* the Delta Clipper prototype, so *maybe*...

Regards,

Northstar

Edited June 9, 2014 by Northstar1989

[Spartwo]

>snip<

So the challenge is for a SSTO rocket.

Edited June 11, 2014 by Spartwo

[Damaske]

I have grown a liking for the Luck Laster Labs mod parts, Are they allowed to be used for the basic shape of the launch craft but use one of the listed mod, or stock engines for its lift. I know some of the LLL Engines are op and don't like to use them unless making something massive, or screwing around.

Also another question is Are we allowed to make a full rocket powered space plane, one that does not use air-breathing engines at all. It would increase the challenge of making a space plane more than the air-hogging designs of the past space planes.

I'd also like to note, most if not all my Space planes that I have made in the past have one or two intakes per engine, Although my Midget Beta 1 SSTO was a clipping air-hog craft. I have moved away from doing so, and thus most my air breathing engines cut out before 20 km up, some i have to go to rocket power at 16 to 20km.

Just a few questions and comments still deciding if I'd like to take a wack at this. If allowed to use LLL parts for this challenge will help me to decide.

Damaske

[Jouni]

I built an upgraded version of my SSTO rocket. More fuel for the boosters, 69 parts, 973.2 tonnes at launchpad, TWR approximately 1.0998, four crews of three kerbals each for redundancy (but the probe core ignores them all), delta-v 4153/4970 m/s, and a slightly smaller 102-tonne payload.

Now it should qualify for Motherland Lifter, Slow Climber, and possibly Home in Time for Dinner.

[Northstar1989]

So the challenge is for a SSTO rocket.

No, not at all. You can use reusable (recoverable) drop-tanks or boosters, a Space-X style reusable (provided you recover both stages- look up how Space-X's Falcon 9r is proposed to work if you have no idea what I'm talking about), or shuttle-style vehicles (Vertical Takeoff, Horizontal Landing) with a reusable booster.

More advanced strategies don't focus on the vehicle at all, but its ascent profile- like making use of altitude-launches from Kerbin's mountains (the better ISP on the launchpad and reduced atmospheric drag make this significantly worthwhile both in-game and in real life), blimp launches, or even mothership launch platforms...

If there was a good (realistic and non-buggy) mod available for this, I would even allow magnetic launch-assist rails.

I also *DO* allow Microwave Beamed Power, and have decided to upgrade the maximum beamed power to whatever you can produce with 42 GW in raw/thermal power of generation-capacity (note this *heavily* rewards at least some reliance on beamed solar power- 100% of nominal solar panel capacity is turned into electricity, whereas nuclear reactors have to make use of a generator to convert an upper limit of around 30% of their Thermal Power into electricity... So you are allowed to use over 3 times the power at the receiving end if you use solar rather than nuclear...)

The point of this thread is to allow reusable launches with technologies realistically available today. Ask me if you want to try something else strange and wacky- an in-atmosphere refueling of a fly-back booster or your shuttle, for example (I'll allow it, provided that the refueling plane or blimp has the capability to land back at the KSC 100% reusable, and doesn't have over a 3:1 intake ratio...)

Regards,

Northstar

Edited June 15, 2014 by Northstar1989

[Northstar1989]

I have grown a liking for the Luck Laster Labs mod parts, Are they allowed to be used for the basic shape of the launch craft but use one of the listed mod, or stock engines for its lift. I know some of the LLL Engines are op and don't like to use them unless making something massive, or screwing around.

Thanks for asking me. I'm trying to create rules that can form guidelines, but I'm certainly not unreasonable. Go ahead and use the LLL structural parts (the engines remain off-limits) - just let me know what parts you use in the entry post, and what their dry mass , fuel capacity, and size are if any of them are fuel tanks (given what I know about LLL engines, I wouldn't be surprised if it also has some OP'd fuel tanks).

Also another question is Are we allowed to make a full rocket powered space plane, one that does not use air-breathing engines at all. It would increase the challenge of making a space plane more than the air-hogging designs of the past space planes.

This is a vertical-takeoff thread, so you can't use a spaceplanes in the first place (I respect them, and use them myself- but if it were allowed in this challenge, they would form 95% of all entries). You can use rocket-only shuttles (VTHL) though: in fact, I'm not aware of any shuttles that have used airbreathing engines in real-life...

I'd also like to note, most if not all my Space planes that I have made in the past have one or two intakes per engine, Although my Midget Beta 1 SSTO was a clipping air-hog craft. I have moved away from doing so, and thus most my air breathing engines cut out before 20 km up, some i have to go to rocket power at 16 to 20km.

Yeah, spaceplanes without airhogging are perfectly doable in KSP. In fact, I've build a number of spaceplanes by this point, and I don't think any of them ever made use of airhogging...

Just a few questions and comments still deciding if I'd like to take a wack at this. If allowed to use LLL parts for this challenge will help me to decide.

Damaske

I encourage you to make a submission. I encourage you in particular to try some of the alternative launch strategies which are feasible in real-life, but haven't seen nearly enough usage: such as balloon launches, mothership launches, or mountaintop launchpads...

Regards,

Northstar

Edited June 15, 2014 by Northstar1989

[Northstar1989]

I built an upgraded version of my SSTO rocket. More fuel for the boosters, 69 parts, 973.2 tonnes at launchpad, TWR approximately 1.0998, four crews of three kerbals each for redundancy (but the probe core ignores them all), delta-v 4153/4970 m/s, and a slightly smaller 102-tonne payload.

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_10.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_11.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_12.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_13.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_14.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_15.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_16.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_17.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_18.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_19.jpeg

http://www.cs.helsinki.fi/u/jltsiren/ksp/ssto_lifter_20.jpeg

Now it should qualify for Motherland Lifter, Slow Climber, and possibly Home in Time for Dinner.

Indeed- congratulations on the new Distinctions! I'll have to figure out how to handle multiple entries from one person on the Scoreboard now- don't be surprised or offended if I just change the link to refer to your new entry...

You do realize you could save over 8 tons on lifter mass, and thus actually lift a *heavier* payload than before if you switched all those Mk 1-2 command pods for Mk1 command pods though, right? There's no point in having a 12-Kerbal crew when just one or two Kerbals could have easily gotten you the award... It's both less efficient and less realistic to stick 12 Kerbals on the vessel as pilots when just 1-2 would suffice...

I suggest trying a "scrubbed" (mass-reduced: cut out all the inefficiencies, basically) Space-X style launch for the "Extreme Reusable" Distinction now; or even going for a shuttle-style mission with FAR for "Lift vs. Drag", or glide-back boosters (use Burn Together plugin to allow you to control multiple ships in-atmosphere at once) for "Glider Return"... If you want to collect some more Distinctions, that is...

Your SSTO would have gotten even better performance/range with FAR installed, by the way. That's generally one of the nice things about rockets with low TWR on the launchpad using FAR- due to the length they typically have, there is a lot of aerodynamic-shielding going on that GREATLY reduces drag vs. stock levels...

I've never been a big fan of rocket SSTO's, since they're so unrealistic (in REAL LIFE, getting to orbit takes 9-10 km/s, due to Earth's much larger equatorial radius. Try building a SSTO that can accomplish THAT with decent payload size...) Space-X style launches, on the other hand, work great in KSP- provided you can achieve a sufficiently high apoapsis with your first stage to allow upper-stage circularization before you have to switch vessels again and land the launch stage...

Speaking of which, I encourage SOMEBODY to attempt the "Ultimate Challenge". C'mon, it's Real Solar System (which has the main effect of making Kerbin/Earth larger, requiring greater Delta-V to orbit due to the larger equatorial radius, despite the gravity remaining the same) and FAR- not a long list of mods that would take you forever to install...

Regards,

Northstar

Edited June 15, 2014 by Northstar1989

[schroedinger]

I encourage you to make a submission. I encourage you in particular to try some of the alternative launch strategies which are feasible in real-life, but haven't seen nearly enough usage: such as balloon launches, mothership launches, or mountaintop launchpads...

Hi Northstar, I interpreted your challenge a little bit and wanted to add realism to the whole thing - not just send up a mock payload and have the lifter return with minimum delta V to deorbit. Since anything can go wrong, I decided to put a Kerbal in the rocket as well. At least any mishap would be attributed to kerbal failure, not blamed on the design.

First, let's start with the payload. This is a small satellite equipped with a little bit scientific instrumentation and independent propulsion capacity. Total weight 149kg. Due to mission characteristics, the payload will be deployed at an orbit as designated by the challenge.

This is the ready to launch rocket. Making heavy use of KW Rocketry parts, it is more of a VTOL spaceplane.

The outer tanks are detachable by hydraulic manifold (darn you for disallowing radial decouplers, they are significantly lighter) and are recovered by parachute. In addition to the fuel tank, the drop section contains two strong ullage motors as well as a solid rocket booster to guarantee a stable flight and fast initial ascent.

The main rocket thrust for ascent is supplied by a single aerospike motor that is also responsible for decelerating the spaceship to suborbital velocities once the mission is complete. Additionally, the motor can supply thrust during the glide phase if additional course corrections are necessary.

Electrical and flight control systems are located in the cockpit which also houses the "guidance system", a single Kerbal chosen for his unique abilites.

Liftoff with all engines blazing accelerates the rocket up to 200 m/s. The flight profile is a little bit unique since the spaceship is quite heavy at launch. After the solid fuel rockets burn out, speed drops to 79 m/s due to drag (around 4km height) and slowly resumes acceleration.

Separation of the drop tanks occurs around 11,5km. You can see the 'chute deployment here. In lieu of recovering them I have included a separate photo showing the descent. 8m/s shortly before splashdown should be more than survivable.

This is the circularization burn, still using ascent guidance to guarantee meeting the mission requirements. Not that we can really trust Rodsen Kerman ..... he was chosen for his stupidity (and expendability) above all other qualifications.

This is payload separation (undocking) and proof of correct orbit. Please note that the mission package has not used any of its onboard fuel yet.

Slowing down to suborbital velocity requires only very little actual braking. The main advantage of a plane is the much more reasonable handling while performing a low angle reentry and less heat stress during aerobraking. A traditional capsule at 20km altitude would resemble a shooting star - watch this nifty little plane just flying instead of burning. Even the ground control is amazed (and thankful) that Rodsen Kerman is not filling the airwaves with panicked screams.

This is the terminal approach above Kerbin's desert. Aerobraking fell short so Rodsen did not make it back to the KSC field and rather than firing the engine again and wasting the rest of the fuel, he decided to do a little bit aerial sightseeing and braking maneuvers above the desert. Since the air conditioning is solar powered, he should hold until Jeb can get there with a fuel truck and fly the spaceplane back.

So, I'd say challenge completed or do I have to make another flight and actually video that I did not use quicksave?

[Northstar1989]

First of all, sorry for the slow response- I took a break from KSP for a while, and then when I came back jumped right into 0.24. Additionally, even though I kept checking the forum in the meantime, I have a LOT of threads I've started on the forum, or are involved in discussions on...

Hi Northstar, I interpreted your challenge a little bit and wanted to add realism to the whole thing - not just send up a mock payload and have the lifter return with minimum delta V to deorbit. Since anything can go wrong, I decided to put a Kerbal in the rocket as well. At least any mishap would be attributed to kerbal failure, not blamed on the design.

First, let's start with the payload. This is a small satellite equipped with a little bit scientific instrumentation and independent propulsion capacity. Total weight 149kg. Due to mission characteristics, the payload will be deployed at an orbit as designated by the challenge.

http://i.imgur.com/WnrtuEc.jpg

Good job of keeping mass low on both the payload and rocket. I bet that would even be affordable in 0.24!

This is the ready to launch rocket. Making heavy use of KW Rocketry parts, it is more of a VTOL spaceplane.

The outer tanks are detachable by hydraulic manifold (darn you for disallowing radial decouplers, they are significantly lighter) and are recovered by parachute. In addition to the fuel tank, the drop section contains two strong ullage motors as well as a solid rocket booster to guarantee a stable flight and fast initial ascent.

The main rocket thrust for ascent is supplied by a single aerospike motor that is also responsible for decelerating the spaceship to suborbital velocities once the mission is complete. Additionally, the motor can supply thrust during the glide phase if additional course corrections are necessary.

Electrical and flight control systems are located in the cockpit which also houses the "guidance system", a single Kerbal chosen for his unique abilites.

http://i.imgur.com/afU43L3.png

You're pushing the limits between a spaceplane and a rocket a little bit, though I'll allow it. And there is no rule against using radial decouplers for reusable drop-tanks or boosters. HOWEVER, in the challenge as it currently stands, you are not allowed to have any part of your rocket be destroyed for any reason- including due to falling below 23 km in altitude.

I am considering allowing use of the new DebrisRefund mod for 0.24, provided that players only drop stages *over the ocean*, as it's completely unreasonable to expect that a stage dropped onto the side of a mountain or even a steep hill would necessarily survive unscathed. It would also be a little unfair to players who made previous submissions to this challenge, so I'm really unsure over whether I should actually allow it- maybe I'll start a new challenge that also includes Cost in the scoring guidelines...

Liftoff with all engines blazing accelerates the rocket up to 200 m/s. The flight profile is a little bit unique since the spaceship is quite heavy at launch. After the solid fuel rockets burn out, speed drops to 79 m/s due to drag (around 4km height) and slowly resumes acceleration.

http://i.imgur.com/tgK8gQR.png

Separation of the drop tanks occurs around 11,5km. You can see the 'chute deployment here. In lieu of recovering them I have included a separate photo showing the descent. 8m/s shortly before splashdown should be more than survivable.

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

http://i.imgur.com/v1gU7j6l.png

Your rocket/plane would fly a LOT better with FAR installed. In particular, it replaces the standard "pea-soup" atmosphere, so you probably wouldn't see your rocket decelerate from 200 m/s down to 79 m/s quite so quickly, as drag is simulated much more accurately/realistically.

This is the circularization burn, still using ascent guidance to guarantee meeting the mission requirements. Not that we can really trust Rodsen Kerman ..... he was chosen for his stupidity (and expendability) above all other qualifications.

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

This is payload separation (undocking) and proof of correct orbit. Please note that the mission package has not used any of its onboard fuel yet.

http://i.imgur.com/gxytXhjl.png http://i.imgur.com/PzMQPUPl.png

Slowing down to suborbital velocity requires only very little actual braking. The main advantage of a plane is the much more reasonable handling while performing a low angle reentry and less heat stress during aerobraking. A traditional capsule at 20km altitude would resemble a shooting star - watch this nifty little plane just flying instead of burning. Even the ground control is amazed (and thankful) that Rodsen Kerman is not filling the airwaves with panicked screams.

http://i.imgur.com/IUf2Wq5l.png

This is the terminal approach above Kerbin's desert. Aerobraking fell short so Rodsen did not make it back to the KSC field and rather than firing the engine again and wasting the rest of the fuel, he decided to do a little bit aerial sightseeing and braking maneuvers above the desert. Since the air conditioning is solar powered, he should hold until Jeb can get there with a fuel truck and fly the spaceplane back.

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

So, I'd say challenge completed or do I have to make another flight and actually video that I did not use quicksave?

A nice entry, all-in-all, but under the current Challenge requirements, it wouldn't qualify due to the separation of those boosters at 11.5 km, and their subsequent disappearance in the atmosphere... A general rule-of-thumb is that, to avoid debris disappearing, you shouldn't detach any lower than about 42 km- by which point they could conceivably have enough upward velocity to not fall below 23 km before the rest of your rocket circularizes...

Regards,

Northstar

Edited September 22, 2014 by Northstar1989

[Son_of_Rambo]

So I gave this a quick shot, took a lot of slimming down for my super heavy lifter to get in under the 128 part limit. So i used some SABRE engines which i know there is some controversy around about so I placed some restrictions on their use. Air-breathing mode was only used between 700m - 25km, with a single air intake used for each engine. Rest of the time the engines were used as a traditional rocket setup.

Cargo was a section for a future Jool Space Station, the section alone weighed in at 182.3 tonnes, cargo was left untouched on ascent (no fuel/engine use). The SSTO lifter combined the use of 16 SABRE engines to provide some heavy lifting (11,840 kN at liftoff) Weighing in at 1087.21 tonnes, not a light weight by any measure. Starting TWR of 1.1. Made an orbital delivery at 102km circular orbit and returned with less than 30 seconds of spare fuel. Normally I would reduce the amount of oxidiser I take up with me but needed to keep it on this time to get in under 1.1 TWR. Launch was assisted by MechJeb (edited ascent profile - still fiddling with this to find the optimal, seems to change with each payload anyways). Return was non-assisted, not enough SAS onboard for MechJeb to lock onto retrograde without the help of the thrusters, so manual intervention needed. Piloted the landing (with quicksaves luckily, first touchdown was at around 100m/s into unforseen hill).

Haven't had the chance to test this on a RSS etc. mod, would need to lower the payload, but hoping it'd be up for >100 tonne lift with only a little modification.

SABRE Grasshopper: http://imgur.com/a/1soHs

At the very least this is a very useful super heavy lifter. Cost per launch is about $80k for fuel (provided you return to KSC). So cost-effective, little stumbling block of being $800k to put on the launchpad though. Very good incentive not to crash

EDIT: *Fixed final cost of lifter (only)

Edited September 20, 2014 by Son_of_Rambo
Incorrect cost of launcher

[Northstar1989]

So I gave this a quick shot, took a lot of slimming down for my super heavy lifter to get in under the 128 part limit. So i used some SABRE engines which i know there is some controversy around about so I placed some restrictions on their use. Air-breathing mode was only used between 700m - 25km, with a single air intake used for each engine. Rest of the time the engines were used as a traditional rocket setup.

Sorry man, but jet engines are banned for anything but "mothership style" planes, and for landing (this is particularly useful for VTHL stages). RAPIER and SABRE were both meant to fall under that category, as they are basically just dual-function jet engines (they are strictly inferior to rockets in terms of TWR, so the only reason to ever use them is if you will be using both modes...)

Regards,

Northstar