Kerbodyne Challenge Series: Spaceplane Tankers

[GoSlash27]

UnusualAttitude,

This is how I worked around the structural problems inherent in Mk.3 structures:

Triangulating the wing sections and tying them together makes the entire assembly rigid.

I'm not going to bother with Mk3 until the new update, but feel free to take that and run with it!

Best,

-Slashy

[juzeris]

Taking Starhawk's insight of "more intakes" to the extreme, and also stealing the wing strakes idea, I've built an aircraft powered with ugly and air, but mostly ugly. It does very extreme airhogging (full throttle at 39km!) and intake stacking (that's 48 ram air intakes to one engine), just as an efficiency thought experiment. I'm not sure if any of that breaks Wheaton's Law , you be the judges, but turns out it does increase the efficiency significantly.

Presenting the Boulderor (download link)

Except for the airhogging, she's a stable, boring craft, easy liftoff, fairly easy landing, rcs for docking (didn't actually test it), reasonably powerful rockets and a light on one of the ailerons for better craft visibility. The climb gets slow at some point between 15km and 20km, but picks up after that. As the turbojet thrust increases with speed (up to 1km/s) it helps to fly horizontally a bit to build up speed before continuing ascent.

Delivered 2416=(1329/11*20) fuel units to orbit (counting based on oxidiser, as the mix came out fuel heavy)

(178931-177594)/2416=0.5533 fund per fuel unit, which is just a 20% markup.

Javascript is disabled. View full album

For flying close the majority of air intakes with 4, rocket engines are group 2 and the jet is group 1.

Also, admittedly, the test craft had 152 parts, as I added 8 solar panels and forgot to check the part count. Two of them are removed for the final craft, and, well, they are massless so do not affect anything for testing.

Same mods used as my previous entry - no part mods or physics mods (I might have left KJR on for this one, not sure, but it's small enough not to need it), MechJeb for flying, HyperEdit for placing the target station in a 80x80 orbit.

Edited April 2, 2015 by juzeris
Added details

[FlipNascar]

So not wanting to flatter the amphibian lovers by imitating, and out of general curiosity and let's face it, really it was laziness... I kept ending up with something that looked the same because clearly I'd seen it was efficient. So to that end I modified a 16-pax spaceplane that I already had laying around to become a fuel tanker. Rather than tie up weight and parts with thrusters for docking, I hyperedited a probe-fueltank and had the station dock with the tanker - it's a feasible idea... Overall, pleasantly surprised at its efficiency. It was not expected.

Ended up overdelivering oxidiser to a 75x75. Could do more if I balance out the load a bit better and do a better job of the ascent profile. But this was this poor Abortion's first flight! I think it's awkwardly pretty. Did have a MJ module on this flight.

LF: 2,497

O: 3,428 which balanced to fuel = 3,051

At launch: √158,465, 5,020 LF, 5,940 O.

At RV w/ Fuel Station: 2,608 LF / 3,574 O

Launch consumed: 2,412 LF / 2,366 O + Transfer to Station (2,497 LF + 3,051 O Balanced)

Total Fuel cost including delivery: 4,909 LF and 5,417 O

LF costs √0.8/unit, while O costs √0.18/unit. So that's √3,927.50 for LF and √975.06 for O, making a total fuel bill of√4,902.56. Divide √4,902.56 by 5,548 units of fuel and we get √0.88/unit through the Stock souposphere.

Theoretically, using this as the basis, this flight could have done it for 0.85 per unit (Dividing fuel bill 4,902.56 by remaining fuel, balanced, at RV (2,608LF + 3,188 O = 5,796). Assuming then that you'll get out and push it back into the atmosphere...

Download the Abortion here (107 parts - no MJ unit): https://www.dropbox.com/s/7o2egxm5ygx9j39/Abortion%20Tanker.craft?dl=0

Pics:

Javascript is disabled. View full album

[UnusualAttitude]

Thanks for the ideas, Slashy. I'm actually going to have to find a way to spread the wing more along the length of the aircraft (like your Mk2 designs) rather than stacking them (which probably won't work in FAR).

[GoSlash27]

Thanks for the ideas, Slashy. I'm actually going to have to find a way to spread the wing more along the length of the aircraft (like your Mk2 designs) rather than stacking them (which probably won't work in FAR).

Yeah, that'll probably be a bust in FAR.

That's another problem with the Mk3 parts; the available wings have too little lift coefficient, so you wind up with silly wingspan requirements for the little real estate available.

For example, a single Mk3 section weighs 14 tonnes but only has enough area to attach 1 large wing section, so you need a span that goes out at least 7 panels. Gets a bit unwieldy...

Best,

-Slashy

[Hodo]

Thanks for the ideas, Slashy. I'm actually going to have to find a way to spread the wing more along the length of the aircraft (like your Mk2 designs) rather than stacking them (which probably won't work in FAR).

For FAR you can make quite large wing areas like this.

Javascript is disabled. View full album

This craft can land at around 60-70m/s while fully loaded. And still achieve orbit with ease, granted this craft isnt designed to haul more than a simple probe or satellite into orbit.

Not any of my usual large designs.

[GoSlash27]

Well...

I tried to push the limits a little bit further and failed.

Apparently 25 tonnes is just too much to ask of one engine.

I succeeded in building my most beautiful failure, but that's about it

Best,

-Slashy

Edited April 3, 2015 by GoSlash27

[Starhawk]

It's funny you should say 'beautiful failure'. I called this thing 'Beautiful Tanker' before I tested it.

Now it's just another (subjectively) beautiful failure.

Of course, it's also 229 parts.

Happy landings!

Edited April 3, 2015 by Starhawk

[GoSlash27]

Try as I might, I just can't squeeze enough efficiency out of this platform to bring 1 more tank without eating into the payload.

What I ended up with matches the PeaceFrog in terms of efficiency, and is also the prettiest/ best flying spaceplane I've ever created.

So just on that basis alone, I've decided to share it here.

http://wikisend.com/download/513446/WindWalker3.craft

Best,

-Slashy

Edited April 4, 2015 by GoSlash27