simple is best!

[Umlüx]

i always struggled with spaceplanes. every time i over engineered them, used too many mods, prioritized looks over function...

today i started my ksp and just threw together some stock parts. i didn't even check COM and COL.... and it worked like a charm. it flew like an angel and reached orbit with 3/4 oxidizer left!

SIMPLE IS BEST, FOLKS!

[Richy teh space man]

Great job, how's it land?

[Umlüx]

Great job, how's it land?

piece of cake

[Sirrobert]

Is it the angle, or is there a wing missing in that last picture?

[Umlüx]

haha you're right it looks like the wing is missing!

but its only the angle of view.

[Vlk]

I don't want to be a jerk, but what are you going to do with all the oxidizer you spared?

(hmm, are those screenshots taken from different flights? the ratio of liquid fuel compared to oxidizer is better on the second shot than on the first)

edit: but still very effective, and nice looking ship, i am a fan of simplicity as well - since the career mode forced me to work with smaller parts

Edited December 12, 2013 by Vlk

[Sirrobert]

I don't want to be a jerk, but what are you going to do with all the oxidizer you spared?

You could breathe it XD

[OneEyedShark]

I don't want to be a jerk, but what are you going to do with all the oxidizer you spared?

(hmm, are those screenshots taken from different flights? the ratio of liquid fuel compared to oxidizer is better on the second shot than on the first)

might be becuase it's two different flights?

[Bishop149]

I don't want to be a jerk, but what are you going to do with all the oxidizer you spared?

Given that there's a lot of liquid fuel left too he could head on to the Mun. . .

My 2nd best spaceplane is also very small, the below is very easy to fly a solid as a rock:

My new best one can make orbit with >3000m/s DeltaV left. I'v taken it to minmus and back, I'm gonna see if it can make Duna:

Edited December 12, 2013 by Bishop149

[Umlüx]

it is one flight

but i came in to steep and used the jets on my KSP approach -> more LF used.

[Spatzimaus]

Yes, if your goal is to get an SSTO spaceplane to orbit, you're better off keeping it small and simple. Because of the 10:1 scaling issue you can build up more than half the necessary orbital speed using only jets, so it's pretty easy to get to orbit with even low-end parts once you know what you're doing. It makes a very good starting point for people who haven't tried spaceplanes yet; a lot of people really overbuild on their first attempt, simply because with rockets bigger usually IS better. (You should have seen my own first attempt. It was horribly overbuilt.) Of course, looking at your wings you're clearly clipping some parts, so it's hard to really gauge how heavy your design actually is.

The hard part comes when you try to add more to it than that basic orbital capability. Adding anything beyond that baseline requires a substantial investment in weight, which in turn requires more engine power and fuel to carry it, which quickly spirals out of control. Common culprits:

> A lot of spaceplanes use an LV-N instead of an aerospike so that they can fly to other planets; besides the fact that the engine alone weighs 2.25 tons, an LV-N has too little engine power to get you to orbit if you're carrying enough fuel to actually get to those other bodies (or even Mun/Minmus in some cases), and that means stacking on some other low-efficiency propulsion as well just for the transition to orbit. (In 0.23 you'll be able to use SABERs for this, which'll help quite a bit.) Also, a 60kN engine like an LV-N can only hit a TWR of 2 on Mun if your design is 18 tons or less; any heavier, and you'll have problems taking off from Mun (or landing, for that matter), which really limits your destinations.

> If you want to get all the way to Laythe, even an LV-N won't really be efficient enough unless you're very careful with your slingshots or remove absolutely every nonessential part to save weight. Now you're looking at putting ions on your design, which requires not only xenon and ion engines, but plenty of power generation as well (something a simpler spaceplane has no need for). Solar panels don't weigh much individually, but to get enough power to run two ions at full power you'll need a pretty good number of panels, plus batteries and possibly an RTG for emergency eclipses, and so on.

> If you want to land on airless bodies, you need to either add a set of downward-firing rocket engines, or else add landing legs and ladders so that the plane can land on its tail. I personally prefer the second option, but either way will cost you about a half a ton of mass.

> Then there's all the miscellanea. Science gear, lights, extra flaps for maneuverability and easy takeoffs on places like Laythe, docking ports, ladders, maybe a winch, RCS for docking, that sort of thing. Again, individually these don't weigh much, but it all adds up.

(Also beyond a certain size you start needing struts to hold it all together rigidly, but for now those don't add mass.)

> And finally, payload. A spaceplane that just gets a single kerbonaut to orbit is nice for bragging rights and all, but it's nothing you can't do far more easily with conventional rockets and they're capable of much more. But if you make one that can deliver a pair of ion-powered mapping probes capable of reaching Jool's moons, or carry kerbonauts to and from a space station, or that sort of thing? Now the design is useful, but this sort of thing has a tremendous cost in weight.

Do all of that on one design, and the weight really starts piling up. Once you get above about 25 tons a 2-jet design just won't cut it any more, so you add a third jet, which adds another 1.2 tons and requires even more jet fuel... and then we hit the intake issue. To get enough intakes to lift a heavier design to orbit you either have to abuse the clipping exceptions, make a really ugly design, or use mods with bigger intakes (like B9) that have worse mass efficiencies, and that only gets worse once you add that third engine. In the end, you get something like my personal spaceplane, weighing in at about 34 tons:

It's pretty, can fly to Laythe and back, handles beautifully in-atmosphere, and lands on airless moons without a problem. But it's definitely NOT small, especially not the version that carries those probes I mentioned.

So yeah, it's good to make those small spaceplanes at first. Just don't expect that to really work in the long term for all the things you're going to want to do.

Edited December 12, 2013 by Spatzimaus

[NQMT]

Simple, hey? Don't let Whackjob see this...

[Umlüx]

at least i have a working design now

next step is to add a docking port and some 1man cans to make it a crew shuttle

[Madrias]

Simple is nice. Some of my best designs started simple, getting complex as I needed more out of it. I've gotten to orbit with twin LV-N's, but it was based on a plan to dock with a Rockomax Jumbo-64 in orbit and refuel from that, along with being able to carry it whenever it was needed to travel longer distances.

Admittedly, it was a horribly inefficient design, but it worked.

[Kanukki]

i always struggled with spaceplanes. every time i over engineered them, used too many mods, prioritized looks over function...

today i started my ksp and just threw together some stock parts. i didn't even check COM and COL.... and it worked like a charm. it flew like an angel and reached orbit with 3/4 oxidizer left!

Looks great, Umlüx. I'm trying something similar, but not sure if it is design or piloting that is limiting my escape from Kerbin atmosphere. Any chance of a .craft link so we could give yours a try?

[rkman]

Hm, so we might just as well forget about rockets, space planes are so much more efficient. Maybe a bit of re-balancing is in order...

[Umlüx]

sure: http://www.umluex.at/files/DaFraunz.zip

just pull up to 10km, slowly level down until 20km, then build up speed and height. it is easily capable of 30km+ and 2000m/s+ on jets alone if you throttle down a bit.

hit 1 to shut down jets and fire up the spike.

[stibbons]

Of course, if you're not intending to go to space today, you can get very simple indeed.

[Kanukki]

sure: http://www.umluex.at/files/DaFraunz.zip

just pull up to 10km, slowly level down until 20km, then build up speed and height. it is easily capable of 30km+ and 2000m/s+ on jets alone if you throttle down a bit.

hit 1 to shut down jets and fire up the spike.

Thanks so much, giving it a try now!

[Vlk]

it is one flight

but i came in to steep and used the jets on my KSP approach -> more LF used.

Hmm, i'm just testing my math skills I think i made an error, but i think the retroburn to get back to the atmosphere is responsible for the values.

on the first picture the liquidfuel tank is 62%, the oxidizer is 73%

on the second, the li is 47%, the oxidizer is 52%

so you burnt 15% li, and 21% ox, and i thought that this is impossible, because you should have burned the same amount of ox and li, or more li. But now i realized that if you have a li tank, then burning in the atmosphere would burn more percentage of oxidizer - so its ok

[Umlüx]

i think the values are misleading. i have one rocket tank and two pure fuel tanks on this, so the LF value is higher.

[Seret]

You seem to be packing a lot more monoprop than you need, too!