What can this single stage plane do? It can make it to low Kerbin orbit, Hohmann transfer to the Mun orbit and land on the Mun without refueling. Upon arriving to the Mun base it can be refueled by rover, fly back to Kerbin, land on KSC runway and be recovered at 100% cost.
Thus, this craft creates an opportunity for very cheap (fuel costs only) flights to Mun and/or Minmus and back.
No modded parts used, only stock ones. I used Mechjeb for precise manevering but this plane can do the job without it.
How to fly it (using Mechjeb):
1. Get into orbit
a) Set aschen angle 20 deg (Heading 90, Pitch 20, Roll 0) and fire Rapier engines
b) Rapier engines in airbreathing mode will rise your apoapsis to about 40 km
c) After switching to rocket mode they will take you as high as 80 km apoapsis
d) As soon as your droptanks well become empty - drop them (stage)
e) After you run out of rocket fuel - enable Nerv engine and use it to circularise
f) Open solar panels by pressing 1
g) If you've done everything right - you will now be in stable low Kerbin orbit with about 2500 delta-v left. You need at least 2200 delta-v to succesfully land on the Mun, and much less for Minmus.
2. Get to the Mun orbit
a) You need stable circular Munar orbit with almost 0 inclination and altitude of at least 25 km. If your altitude will be less than 25 km - your landing attemt may fail due to low thrust of Nerv engine
b) Perform Hohmann Transfer to Mun
c) Thansfer to Munar SOI and circularise at 25 km.
d) If you've done everything right, you still have about 1200 delta-v left for landing
3. Munar landing
a) You need at least 900 delta-v for soft munar landing
b) Select your landing spot about +~50 meters far from your Munar base
c) Launch Mechjeb landing guidance
d) Press 9 to deploy vertical landing gear and docking port for refueling
e) If you've done everything right - you'll be able to land on the Mun with almost no fuel left
4. Refuel the craft
a) Use munar rover (not provided in this package) to refuel the craft
b) You should refuel not only liquid fuel but also add some (about half) rocket fuel for takeoff.
You'll need Rapier engines for takeoff, as Nerv engine won't have enough power to raise now heavy craft to orbit)
5. Get back to low Kerbin orbit
a) Launch to low Munar orbit (use both Nerv and Rapier engines)
b) Use "Return from a Moon" to go back to Kerbin, but keep periapsis out of the atmosphere
c) Change your inclination to 0
d) Circularise at 75 km altitude
6. Deorbit
a) Rebalance fuel on the craft to the fore (or your craft will be uncontrollable in flight)
b) Close all panels (1), vertical landing gear (9), ladders, docking ports etc.
c) Create a maneuver node for reentry. I usually create a 300 m/s2 retrograde burn
d) Adjust position of your maneuvering point - your final trajectory should point directly to KSC
e) Perform retrograde burn
f) Reentry:
-Set Heading 90, Pitch 0, Roll 0
-Disable Nerv (2)
-Enable Rapier engines (3)
-Switch Rapier engines to airbreathing mode
-Do not use airbrakes during reentry
g) if you've done everything right you'll be out of hyperspeed and in stable flight just ~50 km before KSC
7. Land at KSC runway (this is a tricky part)
a) If you want to use autopilot - use old "Spaceplane Guidance" from MechJeb 2.6.
It is still working for now (my current game version is 2.4.2), newer MechJeb (2.7) versions at this point seem to be useless.
b) Mechjeb only controls the heading of your craft, keeping it on the glide path. You need to adjust throttle manually
c) Keep your craft in steady flight (90-0-0) until speed falls to less than 500 m/s, then enable the MechJeb spaceplane guidance
d) Do not let speed of your craft to fall below 200 m/s as the craft may stall and become uncontrollable, adjust throttle to do that.
e) After descent to less than 1 km altitude, with about 10 km from runway begin to slow down below 200 m/s. You can use throttle and/or brakes to do that.
f) you final landing speed should be 70 +-10 m/s. If it will be higher the craft may crash,
if it will be lower - it will stall and also crash. Open te landing gear and prepare for landing.
g) When you hit the runway immediately press 7. This will:
-Shut the engines
-Release drogue chutes
-Enable both gear brakes and airbrakes
h) If everything goes well - you'll soon stop on the runway
8. Alternative landing
If you don't want to perform a risky runway landing (or if something suddenly goes wrong and your craft becomes uncontrollable) you can always use alternative landing method.
a) To do that just press the panic button (Abort). This will:
-shut your engines
-Release normal and drogue chutes
b) Open vertical landing gear (9)
c) Perform a vertical landing
9. PROFIT!!!
========== Controls ==========
1 - toggle space/atm mode (panels etc.)
2 - Nerv engine on/off
3 - Rapier engines on/off
5 - Rapier toggle mode (Atm/vac)
7 - Runway braking (engines off, brakes, braking chutes)
9 - Vertical landing gear and ladders
G - Horizontal (runway) landing gear
Brake - Airbrakes
Abort - Panic button: shuts off engines, drops fuel tanks (if any) and releases all chutes
Enjoy!