Bee payload SSTO Series (High payload fraction)

[carazvan]

Presentation

Introducing the Bee pSSTO series. Simple yet effective SSTOs capable of carrying large payloads to LKO with low part count and high payload fractions:

pSSTO Bee (5t) - 98 part count, 25.2% payload fraction

pSSTO Bee (10t) (13.5t)- 140 part count, 37.6% payload fraction *retested with higher payload

pSSTO Bee (25t) - 236 part count, 34.2% payload fraction

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*the weights and fractions presented simply represent what I've tested and taken to orbit the max of the ships might be a little higher

**While there are awesome posts of large cargo SSTO's by people like pa1983 (also known as C4Virus: link here) those SSTO's have over ~1k parts which makes them unusable for most computers without messing with the physics engine

Action Groups

pSSTO Bee (5t,10t)

1- toggle turbojet engines

2- toggle rocket engines

3- toggle air intakes (all)

4- toggle ladders (all)

0- toggle payload docking/detachment

pSSTO Bee (25t)

1- toggle turbojet engines

2- toggle rocket engines (ascent)

3- toggle NERVA engines (circularization)

4- toggle forward air intakes

5- toggle rear air intakes

6- toggle ladders (all)

0- toggle payload docking/detachment

Ascent profile suggestion

The simplest/most effective way I've found to get these spaceplanes to orbit is to level off at 22.5k altitude and as you reach terminal velocity pitch up to climb higher.

On reaching 30k and going 1600+m/s switch to rocket engines on a 45* climb

(As long as your Ap keeps increasing you should be ok even if your speed drops a little until you get above 35-40k)

*for pSSTO Bee (25t) you can switch over to rocket engines at 30k & 1500m/s+ and you should switch to NERVAs only at 50k

Known Problems

When coming in for a landing with the Bee pSSTO (25t) only use the rear air intakes (action group 5) as otherwise the extra forward drag can cause your craft to lose control if more than 15-20* from curent velocity vector

Download

pSSTO Bee (5t)

pSSTO Bee (10t)

pSSTO Bee (25t)

Other similar payload SSTO Designs

antbin

U-Haul LT - ~370 parts, 40t payload, 30.5% payload fraction

Edited September 26, 2013 by carazvan
retested 10t now 13.5t craft

[astropapi1]

Finally someone decided to create useful cargo SSTOs.

[carazvan]

Here's an album of Bee pSSTO adventures:

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Bee pSSTO Mission List

**currently empty but any Bee pSSTO missions will be linked to here**

Contribution/Suggestions

**currently empty but any thoughts are appreciated**

[littlebattler]

Finally someone decided to create useful cargo SSTOs.

Making cargo spaceplanes capable of doing SSTO flight is not easy, you know. Intake spamming is one of the few ways it can be done and quite a few people don't like doing it, either because they think it's cheating or it makes the plane look terrible. After getting past that, there's still balance issues and whatnot, and ground clearance provided by the landing gears is barely enough to keep 2m parts from touching the ground. Cargo SSTOs might be useful, but they're not easy to design.

Anyways, good job OP for making a cargo SSTO.

[Rune]

Finally someone decided to create useful cargo SSTOs.

I've got three or four myself, and have seem many, up to and including 50+ mT shuttle systems. You know, more than two orange tanks up there. This one here is a rather small cargo SSTO, actually.

As to the OP, I'd clip those intakes together for aesthetics, and move them backwards for stability. Just my two cents, but eyeballing it, the stability part is going to be important, being such a short plane.

Rune. Don't say never in these forums.

Edited July 30, 2013 by Rune

[carazvan]

Besides stupid mistakes like >45* angles vs heading I've only had 2 stability issues so far:

-in my 20t SSTO once I hit about 20k altitude it start drifting/rolling right for some reason (hence the delay in bringing it out)

-if you engage the air intakes and are in full reentry (over 1500m/s) and move more than 20* vs heading you'll find yourself in trouble

[Von Gobble]

It's funny, Your "bee" craft is nothing like mine . Well done though, cargo ssto are troublesome ladies to make even on good days .

Edited July 30, 2013 by Von Gobble

[carazvan]

After much tweeking and adding/moving of parts /air intakes the 20t Bee turned into a 25t payload ship. Don't be worried if the SAS controlled surfaces go crazy under 500m because it does keep heading but you just have to fight it a little for initial turn.

Also if anyone can figure out where the right yaw is coming in this aircraft or the SSTO Ant I'd appreciate the input. Currently my only option was to add more reaction wheels to counteract the weird effect that happens only when I climb to around 20k altitude.

[antbin]

if anyone can figure out where the right yaw is coming in this aircraft or the SSTO Ant

Ideas:

* Sometimes clipped parts exert 'phantom force' on the craft. Usually not wings though.

* Un-strutted engines can flex the airframe when fired, and even if all struts are symmetric, sometimes the flexing isn't... <- PROBABLY THIS ONE

* Presume fuel flow is symmetric?

* actually that's it

[carazvan]

Ideas:

* Sometimes clipped parts exert 'phantom force' on the craft. Usually not wings though.

* Un-strutted engines can flex the airframe when fired, and even if all struts are symmetric, sometimes the flexing isn't... <- PROBABLY THIS ONE

* Presume fuel flow is symmetric?

* actually that's it

* I didn't turn on any part clipping and the only slight overlap exists on the forward air intakes between themselves and the tank in some small ammount <- I'll try to see if removing any overlap for the air intakes will affect the sudden yaw

* One of the tested versions for the 20t was strutted to high heaven with over half the part count being struts but still exhibited the same sudden yaw <- I'll do another test to see if struts limit the problem to any degree

* I thought that the fuel flow was symmetric but I'll run another test as that would explain why the yaw happens around when I reach 20k

[carazvan]

While working on a big brother for the current pSSTO Bee fleet I retested the old ones to check for problems, ideas and found out I underestimated the payload capability of the 10t craft which I retested with a ~13.5t payload (added another large RCS tank) which got to orbit without issue.

[Vector]

I too have been working on SSTO reusable craft to haul fuel to orbit. I'm focusing more on the reusable aspect and not so much on trying to make a space plane.

It's quite different, as a vertical launch SSTO coming down on parachutes is really a whole different game. I also allow myself MechJeb, which really only matters for two things: preventing flameout on the way up and making sure I don't land in the ocean on the way down. As you can see I also allow myself 'unrealistic' intake spamming.

I had a few attempts that got close to getting an orange tank into orbit (none succeeded). They were beastly with part count, and were extremely difficult to get near-orbital, even when they weren't spontaneously exploding. I scaled back to a half-orange (18t) tank and it's very doable. This one here is 153 parts.

Next I might try a "3/4 orange" with one 18t and one 9t stuck together.

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[carazvan]

Indeed that seems to work nicely. I think a craft file would be appreciated since that's a nice 50% payload fraction

Think you can cut down on parts/weight further if:

-add landing legs instead of the large structural elements and then just have clamps for the launch

-change up the small girder parts with the 'wing structural attachment' or whatever the things that look like they're supposed to be holding engines are called.

The plane aspect should really help only with gliding in for a landing somewhere and it should also be providing some lift while cruising at 30k trying to gain speed. (But I agree all the aerodynamics can cause havoc for the stability of the craft)

[Vector]

Sure, here's the "Half Can" fueler: https://dl.dropboxusercontent.com/u/25339567/KSP%20Craft%20Files/SSTO%20Half%20Can%20Fueler.craft

And I also managed to get a whole orange tank to orbit, though the craft is a bit overkill (405 parts). The engine kept coming off on landing so I went nuts with parachutes.

https://dl.dropboxusercontent.com/u/25339567/KSP%20Craft%20Files/SSTO%20Whole%20Can%20Fueler.craft

Feel free to modify or optimize, especially the latter could really use it.