Cygnus Recoverable SSTO Rockets (15 to 600 tons)

[Kerbal101]

@Zamolxes77 @Sharpy @TomDRV

I've been designing my own rockets using same principle as Warzouz using 1.0.5 with its "heat" directly.

There are just a few things to understand.
A (returning) rocket typically has bad surface area. Plane has dynamics of piece of paper with its wings, rocket is like stone. Rocket full of fuel is like a heavy stone!
This is why the more leftover fuel the rocket has - the longer deacceleration burn it should do. The deacceleration should be directed between prograde and radial - rocket nose on navball should point between retrograde and antiradial (between horizon and sky). Burning strictly retrograde will cause strong periapsis drop, increasing the fall angle.

Another thing is weight distribution. Reason: heaviest part (CoM) will fall first. But typically bigger rockets have bigger fins (CoL).
What does this mean? While the engines weight most, if an empty rocket has too large fins at tail - then the aerodynamics generated near CoL will be so higher than mass, that they will shift CoM upwards.
What does this mean again? A big rocket with too big fins, when empty and returning reversed (engines come first) - will suddenly rotate in most critical altitude!
Solution - less fins or shift weight(fuel) lower to the engines.

 

Finally, the inability to get this thing into orbit, having only two weeks of KSP experience is predictable.
Either there is problem of incorrect gravity turn or the payload is excessive.

[He_162]

I'm currently building a 6000 ton capacity lifter, I was wondering if you had any tips for making these super heavy lifters more stable? It wiggles no matter how much struts are used, where they are placed, or how well I build the rocket.

[Warzouz]

Back in 1.0.4, I used KJR. But in 1.1, I didn't. I didn't used reusable either... I didn't have much problems with wobbling. I found that adding struts between radial stages was very efficient.

Gentle piloting helps a lot too.

[Firemetal]

Wow. These all look awesome!

Great work!

Fire

[Ace76inDC]

Warzouz, love these designs! they've saved two different career saves from the money death spiral.  I've noticed in 1.2 that I have to enable autostrut and rigid attachment, and I usually have to go 1 or 2 sizes bigger than their weight allowance.  Not a big problem if you are recovering them almost everytime!  Unless I am really tight on money I usually turn the boosters around and de-orbit right after the insertion burn, semi-SpaceX style.

[Warzouz]

Struts are VERY heavy. 42kg a part (the cubic octogonal strut is only 1kg), and I think they also have a lot of drag. If you can avoid using them, do so.

[Sun-Guardian]

I really like these designs!

[Warzouz]

Hey,

As the 1.4 airbrakes can bear much more heat than in 1.2 and 1.3, this launchers are easy to use again.

I'm refitting them all with new parts. I'll repack them soon for 1.4.1.

 

EDIT : after some tests

Seems good after 2 tests. Fuel requirement is up. The margin of error is very narrow now. The good news is that Airbrakes and chutes works perfectly. The very good news is that powered landing is not needed anymore. I landed the 150T on land without engines and the 75T in water. That a good surprise.

Edited March 16, 2018 by Warzouz

[Warzouz]

Well, my hope on aerobrakes has passed. It's a bug.

Ingame temp display shows 2400/2400, but part file says 2400/1200 and the Heat menu from KER too. Strangely, I don't had any problem with Airbrakes except on the 200T rocket. I'll need more tweaking.

Other slight problem : I can't reliably land  as near of KSC as I used to do. Maybe, I'm rusty...

Tweaking, more tweaking...