Kerbodyne SSTO Division: Omnibus Thread

[eddiew]

I know you're mostly about the ascent from Kerbin, Wander, but ever looked into something like a Duna hopper? Been pondering whether big wings and in-situ refuelling would allow for an efficient way to get around all the biomes... or whether it's just easier to launch back into a polar orbit ^^

[Wanderfound]

I know you're mostly about the ascent from Kerbin, Wander, but ever looked into something like a Duna hopper? Been pondering whether big wings and in-situ refuelling would allow for an efficient way to get around all the biomes... or whether it's just easier to launch back into a polar orbit ^^

Any of the big ISRU grand tourers (e.g. Krokodil) would work, or the Krokoduck. A Duna flyer needs to be nuke powered, and you'll run into fuel problems after a few hops if you can't refuel. Small Duna flyers are for down and up once with a bit of aerial siteseeing on the way and maybe a little roving.

[eddiew]

Well now I'm wondering how practical a nuke-plane with some rover wheels would be... in Duna's thin atmo, would the drag matter that much? There'd be something cool about doing those ground surveys with a HOTOL

Dunno whether it's really needed though, I guess Duna doesn't have the most challenging of terrain for a bog standard rover; not got a lot of steep mountains, craters, or canyons. What we need is a flying Eve rover! That can land on water/explodium! And which doesn't have a crew, cos they ain't coming back and we know it ¬_¬ Do we know how Eve handles under nuFAR? I've not been near it since 0.90

[Kagame]

If you're looking for inspiration, I'll let you pick up a concept that literally blew my computer's mind (OK, it merely caused constant CTD, but you get the point): a SSTO that hauls two Kerbodyne S3-1400 tanks (e. g., largest size available in the stock game) up to orbit. Granted, I did try this under stock aero, but I always try to follow a nuFAR-friendly wing profile. (Fat lot of good that does me... T_T)

Main rocket engines are a Mammoth and two Mainsails. This is probably the only time that a Mammoth has succesfully been used in spaceplane construction.

OK, i say successful, but I wasn't really patient enough to fly this thing up to orbit. DON'T USE TIME-WARP.

[Wanderfound]

Well now I'm wondering how practical a nuke-plane with some rover wheels would be... in Duna's thin atmo, would the drag matter that much? There'd be something cool about doing those ground surveys with a HOTOL

Dunno whether it's really needed though, I guess Duna doesn't have the most challenging of terrain for a bog standard rover; not got a lot of steep mountains, craters, or canyons. What we need is a flying Eve rover! That can land on water/explodium! And which doesn't have a crew, cos they ain't coming back and we know it ¬_¬ Do we know how Eve handles under nuFAR? I've not been near it since 0.90

You don't really need rover wheels; landing gear and a trickle of nuke thrust do nicely.

What you can do is make a small nuke spaceplane docked to a big fuel tank, and send that to Duna. Glide down to target, rove around a bit, fly back to orbit, refuel and repeat.

An amphibious Eve rover shouldn't be too hard to land with airbrakes and chutes, but making it fly probably isn't practical. You'd be pushing it through boiling soup, in pressures that high-isp vacuum engines can't handle, without jets.

[peachoftree]

How do you manage heat from your nukes? I don't see any sort of radiator system on your nuke planes

[Wanderfound]

How do you manage heat from your nukes? I don't see any sort of radiator system on your nuke planes

It's not normally a problem. Attach the nuke to a tank with a fair bit of thermal mass, attach the wings or tailplane to that part to help with radiative cooling.

The nukes are often getting a bit hot by the end of the circularisation burn (because they've been continuously lit since 20,000m), but you can just throttle down a bit at that stage if it gets worrying. That isn't usually required, though; you can run them at 90% heat without trouble.

[Wanderfound]

Kerbodyne Dunajet.

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Craft file at https://www.dropbox.com/s/vntd4jdvei5ylls/Kerbodyne%20Dunajet.craft?dl=0

[Wanderfound]

Kerbodyne Dunajet II.

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Craft file at https://www.dropbox.com/s/0pk2n0p75sn1qv7/Kerbodyne%20Dunajet%20II.craft?dl=0

[lordcirth]

Here's a challenge for you, Wanderfound. Can you make a pure Ion-powered SSTO? Doesn't have to carry any cargo, but awesome if it could. The real point of such a thing would be to fly to Duna or something, but SSTO would be impressive enough.

[eddiew]

Here's a challenge for you, Wanderfound. Can you make a pure Ion-powered SSTO?

I believe that 1.0.x has broken this concept entirely. Ion engine thrust at sea level is so laughably small they can't reach orbit. Unless someone's proven that wrong in the last few weeks

[lordcirth]

Oh yeah, they did nerf the sea level thrust in 1.0, I forgot. So much for Ion SS-to-Duna. A while ago Wanderfound did post that jet/ion hybrid which was cool, but Ion TWR was really low.

[Wanderfound]

Oh yeah, they did nerf the sea level thrust in 1.0, I forgot. So much for Ion SS-to-Duna. A while ago Wanderfound did post that jet/ion hybrid which was cool, but Ion TWR was really low.

No matter how you do them, ion ships are painful to fly. The TWR is just too low for anything except the intended use (i.e. ultralight long range probes). Even then, you're generally better off just making the probe a bit heavier and sticking to LFO.

[Wanderfound]

Kerbodyne Admiral. Just the thing for keeping your nuke spaceplanes supplied, wherever they are.

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Craft file at https://www.dropbox.com/s/afv5rhtjkhipi9s/Kerbodyne%20Admiral.craft?dl=0

[Wanderfound]

Kerbodyne Express.

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Craft file at https://www.dropbox.com/s/alcykezwh6ytq21/Kerbodyne%20Express.craft?dl=0

[eddiew]

Kerbodyne Dunajet II.

Nice Lot of wing for one of yours, feels like it could be a fun Duna runner ^^

[eddiew]

This was interesting.

. Needed

pulling off - they were good for reducing wavedrag in FAR, but were a drag under stock - and swapped out some LFO for pure LF tanks. Reached orbit with only 350m/s less than under 1.0.2+FAR, and I think it could have done better had I been shallower in my ascent. 1200m/s at 23km is a bit meh.

Need to do a comparison flight with FAR when I get home tonight, want to know what the new thrust curves and flight ceilings do there Been holding off KSP while waiting for this patch so now I'm itching to just pick an aero model and get going

[Wanderfound]

The heating changes have made FAR significantly easier. You can crank up the speed a lot higher before lighting the rockets.

[eddiew]

Air breathers are a lot thirstier than in 1.0.2 though... there comes a point where waiting for your 0.7 TWR on air to get another 50m/s isn't worth it over hitting the rocket button and getting out of the atmosphere faster. But I shall definitely have a shot at FAR with this plane later.

Still, I'll be happy if FAR builders can have some confidence that their craft will also work under stock, even if efficiency will drop a little. The aero differences have kinda segregated the communities thus far

[Wanderfound]

No luck on that front, I think. Normally-arranged mid-wing FAR designs have their CoL too far back for stock, and small-winged ships struggle for lift in stock.

[eddiew]

I guess my design is quite generous on the wing surface, which might be why it's flown ok under 1.0.2 FAR and 1.0.4 stock... the CoL is a couple-of-balls' width back from the CoM, but it handles fine in the thicker atmos - although it does have basically no turning ability above 10km. Guess time will tell as to how many craft are cross-compatible now though

[eddiew]

Interesting... gave the Ocelot 20 mins of FAR treatment in the SPH; lowered the wing weight, got the wave drag down to 2.15, dumped a bit of LF to equalise the weight with the stock version.

Pretty stable in flight, and she went supersonic in a 45 degree climb. After quite a few training runs, got the her up to 1390m/s at 24km, which seems as good as she'll do. Reached LKO with 400m/s left and 120 units of LF spare after de-orbit. Which is all of 10% more than the stock run, and actually less than the original 1.0.2 FAR flight

Further investigation required... cannot imagine why stock would work out better than FAR. Usually FAR is harder to build, but more efficient, which implies something is wrong with my piloting ¬_¬ Might need to see just how shallow I can go from 18km and up.

*edit* 1402m/s at 24km... arrived in LKO with 368 in the tank... I feel like I'm back to being a total FAR n00b, did something change in the last 6 weeks?

*edit 2* Flew the 1.0.2 FAR original. It can't make orbit. Dangit, air breathers are so much thirstier now

Edited June 25, 2015 by eddiew

[blowfish]

Something to take note of before you build any more planes: a new feature is coming in FAR that will dramatically change how area ruling works. FAR will account for the fact that air flows through engines rather than being deflected around them, drastically reducing the effect of both intakes and engines on cross section.

[eddiew]

You know, I'd been wondering whether intakes should actually be a drag factor at all, so that's quite interesting to hear

For the immediate, I'm inclined to start my career with stock aero, because it is simpler to design for, and looks to be around 85-90% as efficient as FAR with regards to spaceplane ascent. Shame about the decreased ISP of jet mode reducing the general range available beyond LKO, but it's nice to see that FAR is neither massively OP, nor cripplingly hard.

Definitely take a second look at FAR when that engine/intake thing happens though. If it made the ascents say 40-50% more efficient, then the extra building effort would be worth it

[Wanderfound]

First for 1.0.4:

Kerbodyne Kitten.

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Craft file at https://www.dropbox.com/s/fe9zwtk6kwuqb97/Kerbodyne%20Kitten.craft?dl=0