Kerbodyne SSTO Division: Omnibus Thread

[eddiew]

I'd expect Scuttler's main problems to be structural failures on the wings holding the "claws" (think about where the lift/drag forces are hitting when you pull up), and roll instability due to the huge proportion of mass out on the wingtips. It can probably be tuned to fly, but it might not be possible to make it a sensible thing to fly.

Oh yeah, it already likes to roll in stock - any tap of the keys sends it further than you want There's already some struts hidden in the arms, it just seemed like a wise thing to do xD

I shall definitely have to try​ to fly it under nuFAR, if only because I find it highly amusing!

[Wanderfound]

Having trouble reaching sufficient altitude for those early-game survey contracts? We've gotcha covered...

Kerbodyne Hiflyer. Never let technology slow you down.

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Craft file at https://www.dropbox.com/s/9vptzzhq8knsoaj/Kerbodyne%20Hiflyer.craft?dl=0

[eddiew]

Having trouble reaching sufficient altitude for those early-game survey contracts? We've gotcha covered...

Does that actually make orbit, or is it just suborbital? Either way, nice solution to a common problem. Test basic jets at 20km, ffff

[Wanderfound]

Does that actually make orbit, or is it just suborbital? Either way, nice solution to a common problem. Test basic jets at 20km, ffff

Very much suborbital; it's designed to hit space once, or 20,000m a few times (for surveys and part testing). Whack a probe core in there and it'd work well as a suborbital tourist carrier.

[eddiew]

Very much suborbital; it's designed to hit space once, or 20,000m a few times (for surveys and part testing). Whack a probe core in there and it'd work well as a suborbital tourist carrier.

I'm not sure I'd want a robot driving my spaceplane tourist bus! Somehow I'd expect at least a pilot and a stewardess to offer me peanuts...

[Kagame]

Hey Wander, is it still possible to go Mach 3+ on jets alone without blowing up? If so, at what altitude, with what jets, and with what intake setup? I've got a couple of designs that fly well, have enough dV (~7,000 m/s range), they just choke way too soon. (Best alt. I've ever gotten without blowing up is 17K before the RAPIERS cut off.)

Edited May 6, 2015 by Kagame
Hey, look, I have a 50th post somewhere. ^.^

[eddiew]

Hey Wander, is it still possible to go Mach 3+ on jets alone without blowing up? If so, at what altitude, with what jets, and with what intake setup? I've got a couple of designs that fly well, have enough dV (~7,000 m/s range), they just choke way too soon. (Best alt. I've ever gotten without blowing up is 17K before the RAPIERS cut off.)

Take them off auto switch and they'll go to 24-27km while still producing useful thrust on air 1 ram/shock per engine should be enough; engines usually die through altitude/air density before they die through lack of intake air (annoyingly).

However 1.0.2 really favours high-over powered SSTOs that can launch themselves into a high ballistic trajectory before they explode due to heat. See top two posts on the previous page for a couple of 3-5 engine brutes that do exactly this. Both pass 1000m/s at 20km on a 20-30 degree ascent profile. You won't however get much past this speed, since heating is really starting to hurt. The idea of a flat run up to maximum speed is sadly lethal now; you have to be on a powerful ascent from mach 2 and up.

[blowfish]

I've gotten to Mach 5 on RAPIERs in 1.0.2 with 100% heating enabled (1 ram intake + 1 precooler per engine). Your ascent path has to be very carefully managed, but it's doable.

[Kagame]

Oh, nobody else uses precoolers. I'll switch to some Shock Cones stat, then. (since I always use a separate Aerospike, I find it easier to just keep the air-breathers breathing air and then switch using action groups.)

[Wanderfound]

Oh, nobody else uses precoolers. I'll switch to some Shock Cones stat, then. (since I always use a separate Aerospike, I find it easier to just keep the air-breathers breathing air and then switch using action groups.)

Ramscoop vs Shock Cone: Shock Cones weigh more and suck slightly less air. But they're lower drag and much more heat tolerant. The intercoolers appear to actually live up to their name, too. Notice how the warning bars are showing on the wings and engines, but not the intercoolers, despite all of them being at a similar temperature:

Edited May 7, 2015 by Wanderfound

[Wanderfound]

Any of y'all been able to get E.V.E. to work properly in 1.0.2?

I get crashes with the HR pack, and massive graphic glitches with the LR version.

[Captain Sierra]

Any of y'all been able to get E.V.E. to work properly in 1.0.2?

I get crashes with the HR pack, and massive graphic glitches with the LR version.

I have not yet thrown on my beautification mods, which includes the highest resolutions of Astronomer's Visual Pack, so I can't say. I'm about to get some rack but I will force 64 bit tomorrow and load on the 8x textures (have to force 64 bit to run all of Nertea's mods, half of Roverdude's mods, and AVP 8k)

[Wanderfound]

Kerbodyne Triskenne. Back to the good old days.

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Craft file at https://www.dropbox.com/s/re2mmiimpcy5d55/Kerbodyne%20Triskenne.craft?dl=0

[eddiew]

Ramscoop vs Shock Cone: Shock Cones weigh more and suck slightly less air. But they're lower drag and much more heat tolerant. The intercoolers appear to actually live up to their name, too. Notice how the warning bars are showing on the wings and engines, but not the intercoolers, despite all of them being at a similar temperature:

IIRC the 'coolers' have a high heat capacity/tolerance, but no active or actual cooling ability... Which makes them counter-intuitively best when bolted to the engine, rather than the intake O_o

Good tip about the shock cones. I'm bemused that RAM intakes always have a drag of 2, at any speed or altitude... I'll swap them out next build and see what happens

- - - Updated - - -

Kerbodyne Triskenne. Back to the good old days.

Yay, some delta-v in orbit again! Still nuStock aero?

[Wanderfound]

Yay, some delta-v in orbit again! Still nuStock aero?

Yup, I'm not bothering with nuFAR until the official release. I hate designing when I don't know if the problems are caused by design or bugs.

[eddiew]

Yup, I'm not bothering with nuFAR until the official release. I hate designing when I don't know if the problems are caused by design or bugs.

Very nice I gave nuFAR a try, but I'm struggling without the calculation windows, and it kind of felt like my plane was hanging on a string and any tiny nudge sent it rolling wildly. That might just been an excess of control surface though; as you say, hard to tell at this stage. Definitely excited for it as a concept though

The turbo/rapier/nuke trio seems to be a very powerful option. Might have to start doing some dirty turbo/nuke clipping to make the thrust balance easy ¬_¬

Is it a general thing that a shallow launch as you've shown is most efficient? I keep being tempted by steep kicks up to high apoapses to get my rockets as near to vacuum as possible before engaging them... and that's definitely safer from a heating perspective. As scary as 1100m/s looks at 20km, when you're going 400m/s vertical it's not a worry for very long!

[Wanderfound]

Very nice The turbo/rapier/nuke trio seems to be a very powerful option. Might have to start doing some dirty turbo/nuke clipping to make the thrust balance easy ¬_¬

Is it a general thing that a shallow launch as you've shown is most efficient? I keep being tempted by steep kicks up to high apoapses to get my rockets as near to vacuum as possible before engaging them... and that's definitely safer from a heating perspective. As scary as 1100m/s looks at 20km, when you're going 400m/s vertical it's not a worry for very long!

I'm still working out ideal launch trajectories in stock; for now, I'm mostly just trying to avoid too much in the way of speed-sapping changes of direction.

As a general rule, though, the flatter the better (so long as you don't give up too much to drag). Doing your acceleration lower allows you to maximise Oberth during the rocket phase, as well as extending the fuel-efficient jet phase. From a ground-vs-space Isp point of view, by the time you're over 40,000m you're pretty much in space already.

The non-nuke version (Triske) cuts it a bit fine in terms of heat tolerance, but this one is comfortably within the limits. The extra intercooler may be making the difference.

Edited May 7, 2015 by Wanderfound

[eddiew]

Righto. My worry with a shallow ascent was spending too long in the hot zone, or running out of jet thrust while still having a lot of drag going on. I haven't had a lot of time with KSP this week, but I'd been favouring a strong kick at 25-30 degrees to mitigate this. Fastest I've gotten to on air with this approach was about 1150m/s, but it certainly wasn't a long range vessel, nor even Munar orbit capable.

Some time I want to play around with turbojets and see how high I can get them to launch me. Reckon that if 150km AP is possible on a 45 degree ascent, that may be enough time even for an unassisted nerva to circularise... maybe. Really I just want to find the limit of ridiculousness

- - - Updated - - -

I have not yet thrown on my beautification mods...

Speaking of beautification mods, has anyone else noticed that New Horizons is now on the new Kopernicus build and updated for 1.0.2? Now without the bug that deletes your ships

http://forum.kerbalspaceprogram.com/threads/114092-1-0-2-Kopernicus-New-Horizons-v1-4-3-5-15-It-s-back-baby%21

Checked it out briefly this morning, and it's looking fantastic! Throw in Scatterer and (hopefully) E.V.E in the future, and it could make for a properly epic solar system ^^

Of course, now I have no idea what sort of delta-v a Mun capable SSTO needs xD

Edited May 7, 2015 by eddiew

[Wanderfound]

Hey Wander, is it still possible to go Mach 3+ on jets alone without blowing up? If so, at what altitude, with what jets, and with what intake setup? I've got a couple of designs that fly well, have enough dV (~7,000 m/s range), they just choke way too soon. (Best alt. I've ever gotten without blowing up is 17K before the RAPIERS cut off.)

This is from before any of the engines have shifted to rocket mode:

If you're having heat trouble, swap the ramscoops for shock cones, stick intercoolers in front of your engines and think carefully about how you attach wings and things. In some cases, you may get better heat dispersal if you alter the attachment point of the wing (and then use the translation tools to slide it back to where it should be).

Edited May 7, 2015 by Wanderfound

[Hodo]

Very nice I gave nuFAR a try, but I'm struggling without the calculation windows, and it kind of felt like my plane was hanging on a string and any tiny nudge sent it rolling wildly. That might just been an excess of control surface though; as you say, hard to tell at this stage. Definitely excited for it as a concept though

The turbo/rapier/nuke trio seems to be a very powerful option. Might have to start doing some dirty turbo/nuke clipping to make the thrust balance easy ¬_¬

Is it a general thing that a shallow launch as you've shown is most efficient? I keep being tempted by steep kicks up to high apoapses to get my rockets as near to vacuum as possible before engaging them... and that's definitely safer from a heating perspective. As scary as 1100m/s looks at 20km, when you're going 400m/s vertical it's not a worry for very long!

NuFAR isn't that bad right now. It isn't 100% but it isn't that bad. The thing is now old designs that we got away with before just DONT work well in a more realistic aero environment.

While something like this was stable and easy to fly previously, it is a handful now.

[eddiew]

NuFAR isn't that bad right now. It isn't 100% but it isn't that bad. The thing is now old designs that we got away with before just DONT work well in a more realistic aero environment.

While something like this was stable and easy to fly previously, it is a handful now.

http://i.imgur.com/AkZPi9r.jpg

Yeah, the plane I tried was a bit like that - twin engine rear-delta wing. Which don't feel like a terrible idea. Clearly there is much to learn about nuFAR - maybe it'll be pushing us towards mid wing conventional shapes?

[Wanderfound]

Yeah, the plane I tried was a bit like that - twin engine rear-delta wing. Which don't feel like a terrible idea. Clearly there is much to learn about nuFAR - maybe it'll be pushing us towards mid wing conventional shapes?

And I was worried that the area rule stuff was going to lead to everyone flying deltas all the time...

[eddiew]

Lol, you and your delta discrimination Although I will admit there's no such thing as a delta wing bird

[Wanderfound]

I've got nothing against deltas per se, it's just...

[eddiew]

I think people just imagine high speed and futuristic planes to have delta wings... visually, they look sleeker, because it feels right that the pointy end goes first :> But on the whole, I have found midwing+tail to be more controllable. And I have tried many delta wing shapes throughout 0.90