1.0.2 - Any hope left for SSTOs?

[Stocchinet]

Mr. roflcopter, i tip my hat to you

[Roflcopterkklol]

Mr. roflcopter, i tip my hat to you

The power of part clipping haha, more of the craft is hidden inside itself than outside haha, someone commented on it weighing as much as one of their capital ships, they aint wrong it should be about twice as big as it is

[Kuu Lightwing]

Wow, Roflcopter, that looks stunning! Now, remove those 2000 unnecessary oxidizer units and try again

Also, if I'm not mistaken, part clipping would be strong with nuFAR, wouldn't it?

[Temeter]

That's some sey hotdog.

It does, but only because air brakes are OP, lol.

I'd rather worry about the CoM being to far to the back with all those engines.

Also, if I'm not mistaken, part clipping would be strong with nuFAR, wouldn't it?

With those voxels? Probably godly. It's kinda funny how adding realism tends to create new exploity ways.

[Sattorin]

I'd rather worry about the CoM being to far to the back with all those engines.

It definitely needs a minor redesign, probably removing the forward-most sent of wings and pulling the canards back. It spiraled out of control for part of the descent, but stabilized at around 4km altitude.

[KerikBalm]

*sigh*

ROFLcopter complains so much about SSTOs, then makes a very-exploity part clipping one, and claims:

"the Nuclear Comet is about as good as it can get when it comes to single stage to orbit"

When I already posted a design that gets >2,000 m/s dV more than his....

Your designs aren't the absolute best, and just because you had trouble getting used to the new aero, didn't mean that the new aero killed SSTOs.

Just because your effort only produced an SSTO with 1,000 m/s left in orbit, does not mean that is the best you can get with SSTOs.

[Wanderfound]

With those voxels? Probably godly. It's kinda funny how adding realism tends to create new exploity ways.

OTOH, massive "wing" loading and a huge angle of attack are going to make it hard to crack the sound barrier; I wouldn't be surprised if the fuselage snaps during the trans-sonic phase.

Worth a try, though.

[eddiew]

...then makes a very-exploity part clipping one...

Other things aside, part clipping does nothing. The aero model only occludes things that are attached to the back node of another part. Sliding something sideways so that it's half-in, half-out of another part does nothing to the performance, it just makes it look better

[Rune]

Other things aside, part clipping does nothing. The aero model only occludes things that are attached to the back node of another part. Sliding something sideways so that it's half-in, half-out of another part does nothing to the performance, it just makes it look better

+1. Unless you clip inside a cargo bay... but we don't do those things, do we?

Rune. And yeah, nuFAR is going to be so easy to exploit.

[KerikBalm]

Other things aside, part clipping does nothing. The aero model only occludes things that are attached to the back node of another part. Sliding something sideways so that it's half-in, half-out of another part does nothing to the performance, it just makes it look better

It does if you attach multiple parts to the same node.... you can do that right? I don't partake in part clipping myself.

Also as mentioned, there's the cargo/utility bays thing...

Also, as far as the structure... it matters. If all your mass is close together, the vehicle won't be as flimsy as if its all spread out.

You also don't need to add certain parts (say a radially attached structural fusalage for example) to make things fit, so that's also an advantage.

Anyway, the part clipping thing was beside the point. Clearly its not that exploit-y, because I can get SSTOs with better mass fractions and dV in orbit, without using part clipping

[GoSlash27]

Same concept as earlier, scaled up to Mk.3 size.

This is the way the airstream sees it on reentry:

The wings bear the brunt of the reentry heating, shielding the more delicate parts from getting all explodey.

Best,

-Slashy

[Peppe]

Haven't had a chance to play 1.0/1.0.2 yet, but noticed this thread and the payload challenge thread and wonder one thing...

How come there is doom and gloom on the SSTO/Spaceplane front while rapiers and jet engines are punching in close to or above a 50% payload fraction in the challenge thread.

I know the speeds and top altitudes have changed, but surely there is room to take the lessons learned in that thread and make a 30-40% payload space-plane.

Payload challenge thread:

http://forum.kerbalspaceprogram.com/threads/116729-Stock-Payload-Fraction-Challenge-1-0-2-Edition

[KerikBalm]

Haven't had a chance to play 1.0/1.0.2 yet, but noticed this thread and the payload challenge thread and wonder one thing...

How come there is doom and gloom on the SSTO/Spaceplane front while rapiers and jet engines are punching in close to or above a 50% payload fraction in the challenge thread.

I know the speeds and top altitudes have changed, but surely there is room to take the lessons learned in that thread and make a 30-40% payload space-plane.

Payload challenge thread:

http://forum.kerbalspaceprogram.com/threads/116729-Stock-Payload-Fraction-Challenge-1-0-2-Edition

#1) Those at 40 and 50% are serially staged - they are NOT SSTOs.

I have the single stage record on that thread, at 33% if you go to my posts, I think I could get to 37%, as my design had a lot of fuel left over. I didn't even design it with payload fraction in mind, but rather just as a cargo carrying SSTO - one that can carry a lot of cargo.

I think a proper SSTO for this specific purpose should be able to push 40%.

In 1.0, I had a SSTO design that should have been capable of ~42% payload fraction. I haven't tried it in 1.02, and seen if the drag killed it (previously, it was borderline with the heating, and the heating often killed it).

- Note that I am also not on the doom and gloom front.

#2) Previously, the SSTOs could exceed 60% IIRC.

So going from the 60's to the 30's, is quite a drop.

Note that most people aren't even getting into the 30's, so I think that is where the doom and gloom is coming from - that is also why I'm posting my design that gets >33% payload fraction, and can accept very large cargos in the fairing, not just whatever you can cram into a mk3 bay (which is not much more than an orange tank)

[Acus]

Hello guys

I had a lot of Fun with SSTO planes , i just love them, i had a nice plane which can go to mun deliver 1 t of cargo and back... (with FAR + DRE ) I used them to make RemoteTech network satelites. And now this...

Ok it is realistic , and in the end i can deal with this , try to build new ones - new challange . But i think, SSTO planes effectiveness dropped so hard that they are useless now. Lets add to this role of planes in Career... useless again... Beside pure fun - there is no point of building planes now... Still soo many nice new parts

I think the best solution for this is scramjet engine. It wont mess with new game mechanics , simple to implement , making ssto planes more complicated but still effective. What do you think ?

[eddiew]

+1. Unless you clip inside a cargo bay... but we don't do those things, do we?

*whistles innocently*

(I actually have no idea whether the bi-adapters get shielded by the cargo bay or not, I never thought about it until now... Looks boss though so I'm keeping it Trying to work out if I can stick a third adapter on the back of the first, then a fourth on the resulting doubled node and have a jet underneath as well for three vertically aligned engines...)

[GoSlash27]

#1) Those at 40 and 50% are serially staged - they are NOT SSTOs.

I have the single stage record on that thread, at 33% if you go to my posts, I think I could get to 37%, as my design had a lot of fuel left over. I didn't even design it with payload fraction in mind, but rather just as a cargo carrying SSTO - one that can carry a lot of cargo.

I think a proper SSTO for this specific purpose should be able to push 40%.

In 1.0, I had a SSTO design that should have been capable of ~42% payload fraction. I haven't tried it in 1.02, and seen if the drag killed it (previously, it was borderline with the heating, and the heating often killed it).

- Note that I am also not on the doom and gloom front.

#2) Previously, the SSTOs could exceed 60% IIRC.

So going from the 60's to the 30's, is quite a drop.

Note that most people aren't even getting into the 30's, so I think that is where the doom and gloom is coming from - that is also why I'm posting my design that gets >33% payload fraction, and can accept very large cargos in the fairing, not just whatever you can cram into a mk3 bay (which is not much more than an orange tank)

All of this, but getting cargo into orbit with a vehicle that doesn't stage is the "easy" part. The hard part is getting the vehicle home afterwards. It's got to survive reentry, find it's way home, and land. Ensuring that this happens reliably requires design tradeoffs that reduce the payload fraction.

Best,

-Slashy

[Octa]

Just before i will spend hours on a design that won't work: Is the combination LV-909+2xTurbojet still possible? I always used the LV-909 because of the good vacuum Isp that gives a good range after i got to space. Now i see mostly RAPIERs.

Guess i'm going for 2xRAPIER with one central LV-909.

[Acus]

Just before i will spend hours on a design that won't work: Is the combination LV-909+2xTurbojet still possible? I always used the LV-909 because of the good vacuum Isp that gives a good range after i got to space. Now i see mostly RAPIERs.

Guess i'm going for 2xRAPIER with one central LV-909.

That my setup too, tried yesterday, but didnt work. Heard that 909 is nerfed too...

They realy need to add scramjet..

[KerikBalm]

All of this, but getting cargo into orbit with a vehicle that doesn't stage is the "easy" part. The hard part is getting the vehicle home afterwards. It's got to survive reentry, find it's way home, and land. Ensuring that this happens reliably requires design tradeoffs that reduce the payload fraction.

Best,

-Slashy

I haven't found reentry to be a problem... the wing loading becomes quite low after consuming fuel and releasing payload.

A high angle of attack in the upper atmosphere keeps my planes safe. I didn't even need to add any airbrakes to that >33% design I showed in the payload fraction challenge.

The hard part now is timing the deorbit, and modifying trajectories within the constraints of acceptable reentry profiles, to come in near KSC... because my large craft are too flimsy to land in the uneven desert... I need the nice runway of KSC, or the surrounding perfectly flat green fields.

I've already lost 1 SSTO in 1.0 from deorbiting safely, but coming in far too short -> got impatient and fired up the jets again -> went too fast too low, and overheated the canards, shifted fuel back, kept flying, but then the plane broke up due to structural forces...

It would have been fine if I had just been more patient

[Esme]

off-topic I know but - 1.02?! I'm still waiting to hear that 1.01 has been released,what the heck happened?!

[GoSlash27]

Just before i will spend hours on a design that won't work: Is the combination LV-909+2xTurbojet still possible? I always used the LV-909 because of the good vacuum Isp that gives a good range after i got to space. Now i see mostly RAPIERs.

Guess i'm going for 2xRAPIER with one central LV-909.

I haven't tried a turbojet hybrid yet.

The RAPIERS run at higher airspeed and altitude than the turbojets, which saves considerable DV on the closed cycle portion of the ascent. That's why we've been using them.

However... the turbojets seem to be able to punch through Mach 1 easier than the RAPIERS. This would allow for more fuel mass at the beginning of the rocket ascent. I don't suspect it's enough to overcome the DV disadvantage, but I could be wrong.

This is something that will need testing.

The LV-909 looks promising for this role. My initial analysis showing the LV-909 to be hobbled was based on bad data. I'm in the process of redoing the analysis now and should have some results up this afternoon.

Best,

-Slashy

- - - Updated - - -

I haven't found reentry to be a problem... the wing loading becomes quite low after consuming fuel and releasing payload.

A high angle of attack in the upper atmosphere keeps my planes safe. I didn't even need to add any airbrakes to that >33% design I showed in the payload fraction challenge.

The hard part now is timing the deorbit, and modifying trajectories within the constraints of acceptable reentry profiles, to come in near KSC... because my large craft are too flimsy to land in the uneven desert... I need the nice runway of KSC, or the surrounding perfectly flat green fields.

I've already lost 1 SSTO in 1.0 from deorbiting safely, but coming in far too short -> got impatient and fired up the jets again -> went too fast too low, and overheated the canards, shifted fuel back, kept flying, but then the plane broke up due to structural forces...

It would have been fine if I had just been more patient

I'm kinda surprised that design deorbits safely, but this is my point. If it doesn't make it back to KSC safely every time it's sent up, then it's not an economically viable system. There's a huge amount of money wrapped up in these vehicles compared to rockets. If we're not confident that we'll get the money back at the end of the flight, then it defeats the purpose of using an SSTO spaceplane.

Best,

-Slashy

[Acus]

I'm kinda surprised that design deorbits safely, but this is my point. If it doesn't make it back to KSC safely every time it's sent up, then it's not an economically viable system. There's a huge amount of money wrapped up in these vehicles compared to rockets. If we're not confident that we'll get the money back at the end of the flight, then it defeats the purpose of using an SSTO spaceplane.

Best,

-Slashy

Is not new idea to brake in high atmosphere , look at Skylon project http://en.wikipedia.org/wiki/Skylon_%28spacecraft%29

Finding good trajectory to land of KSC is matter of few tries ... same way that finding most optimal ascend path with rockets.

[KerikBalm]

Just before i will spend hours on a design that won't work: Is the combination LV-909+2xTurbojet still possible? I always used the LV-909 because of the good vacuum Isp that gives a good range after i got to space. Now i see mostly RAPIERs.

Guess i'm going for 2xRAPIER with one central LV-909.

The LV-909 isn't really a good choice, due to the fact that you still need about 1,000 dV after your jets die out. LV-909s just don't provide enough thrust... maybe for really small SSTO... but I wouldn't count on it. The Rapiers get you going faster, and then you get rockets with good thrust without adding to your frontal area... unless you part clip, your rockets aren't inline with your jets-> draggier...

Rapier-Nuclear hybrids are good, because you can go very heavy on the liquid fuel, without worrying about carrying a lot of useless mass in orbit.

I'd like to do a Jet+LV-N only SSTO, so that it only uses liquid fuel, but I don't think that is workable with the even lower LV-N TWR.

They realy need to add scramjet..

No, they don't... Jets already get you to over half orbital velocity. IRL, a Scramjet won't get you anywhere close to there. THe Turboramjets and Rapiers already have performance better than a SCRAMjet, proportionately speaking.

off-topic I know but - 1.02?! I'm still waiting to hear that 1.01 has been released,what the heck happened?!

Yea, it came out fast, when I saw the complaints, I hesitated in upgrading, but I prefer it... overheating is much less of a concern now, which was the limiting factor on my 1.0 SSTOs. Drag has been increased, but so has lift. I have to slap some more jet engines on my previous SSTO designs, but its good IMO.

I haven't tried a turbojet hybrid yet.

The RAPIERS run at higher airspeed and altitude than the turbojets, which saves considerable DV on the closed cycle portion of the ascent. That's why we've been using them.

However... the turbojets seem to be able to punch through Mach 1 easier than the RAPIERS. This would allow for more fuel mass at the beginning of the rocket ascent. I don't suspect it's enough to overcome the DV disadvantage, but I could be wrong.

This is something that will need testing.

The LV-909 looks promising for this role. My initial analysis showing the LV-909 to be hobbled was based on bad data. I'm in the process of redoing the analysis now and should have some results up this afternoon.

I looked at the .cfg files, I don't see why that would be the case. To me the Rapiers just seem plain better. Sure, they are slightly heavier, and their Isp is 6400 instead of 8,000... but when you start getting high payload fractions, that doesn't really matter... its like if the liquid fuel is 5% or 7% of your total mass... who cares? The mass lost to jet fuel is recovered in the gain from less expended rocket fuel.

I'm kinda surprised that design deorbits safely, but this is my point. If it doesn't make it back to KSC safely every time it's sent up, then it's not an economically viable system. There's a huge amount of money wrapped up in these vehicles compared to rockets. If we're not confident that we'll get the money back at the end of the flight, then it defeats the purpose of using an SSTO spaceplane.

Well, the design I talked about earlier was in 1.0, and was a much more conventional mk3 cargobay based design.

- This is an issue with SSTOs in general... I don't want to deorbit and recover halfway around the world, and lose massive amounts of funds relative to recovery on the runway.

Every design should come back to KSC. And that becomes just a matter or repetition... fly to the same orbital height each time... and figure out where to deorbit to arrive at KSC. Once that is figured out... its routine:

Achieve a set orbit (ex: 80x80)

Cross landmark: (ex: eastern most shore of the big desert)

Peform deorbit burn of X m/s (example: always 200 m/s)

Keep pitch at X until Y altitude (example: 30 degrees until 15 km)

Land at KSC.

More generally, I've found that you can just figure out where to have the blue line intersect the ground east of KSC.... sure sometimes you come in steeper or shallower... but I've found its close enough.

just use the island airfield as a reference point, and you can come in close enough to have a short flight to KSC and a safe landing.

That 33% design can fly super slow when empty, its easy to have a safe landing when toughing down at 50 m/s

If my design breaks apart in the desert and I have to recover the pieces individually, or if it lands in one piece... it still loses massive amounts due to the recovery %.

I can deorbit it with plenty of jet fuel to fly to KSC.... my preivous story was just one of when I was impatient, and going too fast too low, after deorbiting, and then climbing and accelerating again.

I have no doubt it can be reliably landed at KSC for full recovery (plus, there is always quicksaving and quickloading)

Edited May 6, 2015 by KerikBalm

[Octa]

The LV-909 isn't really a good choice, due to the fact that you still need about 1,000 dV after your jets die out. LV-909s just don't provide enough thrust... maybe for really small SSTO... but I wouldn't count on it. The Rapiers get you going faster, and then you get rockets with good thrust without adding to your frontal area... unless you part clip, your rockets aren't inline with your jets-> draggier...

Rapier-Nuclear hybrids are good, because you can go very heavy on the liquid fuel, without worrying about carrying a lot of useless mass in orbit.

I'd like to do a Jet+LV-N only SSTO, so that it only uses liquid fuel, but I don't think that is workable with the even lower LV-N TWR.

As i mentioned, i assume (without any testing in 1.0) that the combination of RAPIERs and LV-909 might work. The Rapiers take the plane as fast and high as possible in jet mode and they have enough thrust for the time critical final kick in rocket mode. As soon as the time critical phase is over, the LV-909 can do the rest of the trip.

I still assume that the poodle and 909 are rather good and fuel saving choices in vacuum as they were in 0.90....i haven't compared the exact changes yet.

[KerikBalm]

Yes, the rapiers get 305 Isp, whereas the 909 get 345.

The poodle gets 350.

Keep in mind Isps have been nerefed on most engines (The LV-N escaped a Isp nerf, but now weighs more for the same thrust, and uses only liquid fuel, which is a pain until you get mk3 liquid fuel tanks)

Rapiers + LV-909 works. Turbojets + lv 909 does not (I think)

But... rapiers alone works

And rapiers + LV-N also works

For some or my large SSTOs, I use the KR-2L -> still has good vacuum Isp relative to the other engines (340 if I remember), and a great TWR.