Project SS - Re-usable single stage space ships for Kerbol exploration

[Hejnfelt]

Project SS - Re-usable Single Stage space ships for Kerbol Exploration

This thread is about my mission to built a single stage re-usable space ship which carries a single stage re-usable lander capable of landing on and return to orbit from all bodies of the Kerbol system excluding Jool.

This challenge poses immediate problems such as what sequence to visit bodies in and what specific requirements exist for different bodies. Obviously the craft perfect for landing on and escaping the Mun is different than one built specifically to land on and escape Laythe. The building challenge therefore requires understanding and minding of several aspects such as:

• Delta-V required for landing / orbit / interplanetary transfer
  
• Atmospheric capabilities
  
• Crew size
  
• Size and weight
  
• Type of craft - plane or rocket
  

Many more detailed questions surfaced during my exploration of different builds and this thread will highlight the successful ones. Successful meaning the particular ship was re-usable, single stage, capable of multiple interplanetary transfers and landing on multiple bodies before returning to Kerbin LKO and landing the crew on Kerbin. It does not necessarily mean it was capable of a single stage grand tour. Also, a ship prototype may find its way to this thread if I learned something new building and testing it.

Space Ships

The Titan - (lander and tug)

The Condor + Falcon - (Mother ship with lander)

Prologue:

After playing around with KSP for a few months I got into the idea of building single stage re-usable space ships with high enough Delta-V to explore the Kerbol system. It became quickly evident that stock parts are not built for a single stage re-usable setup, so I turned to different parts mods for testing. Notably I tried KW, HOME, NovaPunch and B9 Aerospace and a few others.

After building and flying several missions with parts from these mods I decided to restrict my usage to the B9 Aerospace pack as it aesthetically appeals to me but also it seems to be stable. These parts which were mainly made for space plane designs look amazing when applied to space ships.

I should mention that I have made a few changes to some of the parts in the B9 Aerospace pack. The modifications will be listed here and comments on them are encouraged:

• Included SAS module and reaction wheels in square nose cone that drains electricity.
  
• Created new RCS part that holds only 10 RCS fuel and has a dry weight of 20Kg (stock 50 fuel RCS tank is dry weight 50kg)
  
• included LFO fuel into all B9 structural parts with roughly same amount and exact fuel to dry weight ratio as stock orange tanks
  

I hope you enjoy this thread as much as I have enjoyed building these ships.

As a last note I should mention that all ships are launched from the KSC using stock part heavy launchers capable of putting upwards of 300 tons into LKO.

Edited October 12, 2013 by Hejnfelt

[Hejnfelt]

The Titan is my first successful reusable single stage interplanetary space ship capable of landing on and re-orbiting multiple bodies.

Titan build details

The Titan was my first successful SS concept build. I didn't think too much about the capacity to make it all the way around the Kerbol system in one go, the idea was more to explore the possibility of building a space ship with 10Km/s Delta-V capable of visiting multiple bodies and returning to Kerbin. While building The Titan I decided to try detaching the cockpit and re-attaching it with clam-o-tron Sr. docking ports which worked well and didn't look horrible.

I then started modifying the cockpit as a lander using the parts available.

I didn't care much about weight but just kept in mind that a good rule of thumb for the Mun was 1500 M/s landing Delta-V and 1500 M/s ascent Delta-V. So 3 Km/s seemed a good round figure.

Eventually the lander had everything a lander needs including:

• Legs
  
• Solar panels
  
• Batteries
  
• Docking ports
  
• Antennas
  
• Ladders
  
• Lights
  
• Reaction wheels
  
• RCS ports and fuel
  
• Engines and fuel
  
• Parachutes
  

All in all it was a well built lander weighing in around 18.5 tonnes with 3 Km/s Delta-V fully fueled.

The main engine part of the Titan had one purpose. High amounts of Delta-V. But it also needed to be capable of moving around on its own when the cockpit was detached. This meant it needed a probe core, reaction wheels, RCS and fuel plus solar power and batteries.

Eventually the Titan held 10 Km/s Delta-v with the cockpit attached and independently the cockpit lander held 3 Km/s Delta-v fully fueled.

The Titan was launched in one piece from the KSC.

Titan Maiden Voyage

On its maiden voyage Bob, Kelrey and I went to the Mun, Minmus, Duna, Ike, Dres and back to Kerbin.

Dres was by far the most difficult planet to get to. After Ike we still had 5000+ Delta-v left but after encountering and circularizing Dres we were down to 2000. Barely enough to return to Kerbin after landing on Dres.

On the return trajectory with only a few hundred Delta-v left in the tanks we aerobraked around Kerbin and achieved a ca. 100 km parking orbit for the re-usable engine part of the Titan. Barely I might add, as we were aiming for 200 km orbit...

The last remaining fuel was transferred to the lander which burned it all for de-orbit, landing safely using parachutes.

Key learnings

Building and testing The Titan I learned that I really don't need 100s of RCS fuel. This prompted me to create a new part based on the B9 RCS fuel tank that holds 40 parts fuel. The new tank holds only 10 parts RCS fuel. This is more than enough for a lander as I find myself only using RCS to dock and when I accidentally run out of solar power with my solar panels facing away from the sun.

Also I found that using a docking port in the middle of your ship is a good way to decrease stability. The Titan had constant small wobble troubles during long interplanetary transfer burns.

Voyage pics

Edited October 10, 2013 by Hejnfelt

[Hejnfelt]

After The Titan I figured the main ship needed more Delta-V in order to visit more bodies in one trip. With ambitions of visiting more bodies I started looking into the Delta-V requirements for landing on and ascending from those bodies. Immediately it became apparent to me that an 18.5 ton lander will be hard to land on e.g. Tylo and get back to orbit in one stage. Ergo the lander had to be lighter and have more than 3 Km/s Delta-V.

Eventually I built the Condor and Falcon

Condor and Falcon build details

The building really started with me scaling back The Titan, getting rid of all the parts I never really needed or used such as excess RCS fuel. But through different trials I realized that a detachable front cockpit is a good way to basically increase the weight of your lander due to the high weight of cockpits. The weight increases the fuel it needs for high Delta-V requiring heavier engines for high enough TWR for takeoff from bodies such as Tylo which increases the weight even more. A downwards spiral of evil. Eventually I ditched the front detachable lander idea in favor of a simple and detachable lander which is housed inside a cargo bay in the mother ship.

The Falcon was born.

Weighing only 5.5 tonnes with a Kerbal in the seat, it has a VTOL rocket engine at its core. The B9 VTOL rocket engine makes the perfect midsize lander engine ensuring high TWR on all bodies including Kerbin and Tylo but not Eve.

In order to keep weight down I swapped out landing legs for structural elements which are the lightest stock KSP parts. I also used the modified RCS tank with only 10 RCS fuel. I also decided only to include an external seat as the idea is that this lander can swiftly take a single Kerbal onto any body, carry out its mission and return to orbit safely without need for shelter from the elements.

I continued the minimalist design in opting for the lightest solar panels, giving up solar tracking which I found was not really needed on my Titan mission. To store power I opted for the smallest battery holding 100 parts electricity.

I tried many ways of including reaction wheels but eventually I decided to add the square nose cone instead and modify the part in the B9 pack to include reaction wheels.

I guess we all have our things that must be on a space ship and for me it's antennas. For long range ships, there must be large communotrons and for smaller short distance space ships there must be small communotrons. Hence I added two antennas as well.

Lastly I balanced the center of mass so the VTOL works without need of the reaction wheels. The two RCS ports are also aligned perfectly with the center of mass.

The final Falcon build is probably my largest lander achievement so far in KSP. It weighs 5.5 tonnes with pilot and fuel and has exactly 4000 M/s ATMO Delta-V and a whopping 5200 M/s Vacuum Delta-V. Enough to land on and orbit any body in the Kerbol system except Jool and Eve. The Massive amount of Delta-V were also the reasons not to include a parachute on this thing. The parachute reduced the Delta-V by 300 M/s and given that the Falcon uses less than 300 M/s to land on Kerbin I decided to drop it.

The Falcon is a true VTOL and Kerbin certified SSTO craft.

But the Falcon is only half of or rather a tiny part of the craft. The Condor was basically built independently of the Falcon to have copious amounts of Delta-V for interplanetary transfers. In style with the Falcon it is a more minimalist design having mainly less RCS but one big difference. A crew tank. For the Condor I thought it best to consider living space for the crew on long voyages. Therefore even though the Condor can hold 4 crew it is built with 2 crew members in mind. 1 Condor pilot and 1 Falcon pilot and a crew tank for 2 to hold them both. Due to the previous Titan once running out of electricity I decided to up the capacity to 8000 parts electricity.

The Condor weighs ca. 215 tons with the Falcon in its cargo bay. Without the fuel in the Falcon it holds 14278 Vacuum Delta-V.

Together the Condor and Falcon represent the best team I have right now for exploring the Kerbol system in a re-usable single stage vessel.

The Condor launched from the KSC piloted by Bill Kerman with a stock launcher and the Falcon launched to orbit and rendezvous by itself piloted by Jebediah Kerman.

Condor and Falcon Maiden Voyage

For the Maiden voyage I will try to visit as many bodies as possible. I already tested the Falcon on a trip around the Kerbin SOI. Fully fueled it took Jeb from LKO to Minmus, landed, orbited to the Mun, landed, orbited and back to LKO for rendezvous with the Condor for refueling.

1. Falcon first flight - Minmus and the Mun

Key learnings

To be updated

Voyage pics

When voyage is complete I will assemble a summary of pics here. Until then pics can be found in voyage links above.

Edited October 12, 2013 by Hejnfelt

[SpaceSphereOfDeath]

Cool, I like the sci-fi designs

[Hejnfelt]

Falcon first flight - Minmus and the Mun

After rendezvous with the Condor and re fueling after its initial ascent I wanted to take the Falcon on a test flight to either Mun or Minmus. I decided for Minmus because it's the one I visit less often on test flights.

I undocked from the Condor which still had its ascent stage liquid boosters attached and set course for Minmus.

Minmus was easily encountered and I set up a stable orbit at around 30km ASL and descended from there.

On most of the way down I used the engine in its normal position and only for the final touchdown did I use the VTOL capacity of the craft. I have rarely seen that big of a smile on Jebediah's face.

On Minmus's surface the Falcon's TWR is 55+ so I reached an apoapsis above 30km within seconds and easily circularized. At this point I realized the Falcon still had 3500+ M/s Delta-v left and I decided to stop over at the Mun as well on my return to LKO.

I intercepted the Mun in a highly polar fashion and created an elliptical orbit to change my inclination with less Delta-v for more precise equatorial landing, which would make my return to low Kerbin orbit easier.

For landing I applied a similar approach as on Minmus. Kill orbital velocity and then most of my surface velocity while in normal engine position and then at the final touchdown stage, drop the engine 90 degrees and land vertically.

Ascend was again carried out swiftly due to the enormous TWR and for my return to Kerbin I first set up a highly elliptical orbit and then set up an encounter node at my periapsis which I burned, made another orbit around Kerbin for intercept and rendezvoused with the Condor.

I had less than 400 Delta-v left when I docked with the Condor.

[Hejnfelt]

Cool, I like the sci-fi designs

Thanks, me too I hope you will enjoy the voyage descriptions as well.