WhippyNerv IIi, self contained Duna mission

[AeroGav]

For some time, i've known how to get spaceplanes with very low takeoff and landing speed up to orbit with decent delta V.   Landing gear however, wasn't my strong suit, I've just recently updated this with a sensible (though seriously oversized)  conventional tricycle arrangement.    Despite having not flown the craft in six months, i put it down first time...  so  that makes it officially "noob friendly" yes?

https://kerbalx.com/AeroGav/WhippyNerv-IIi

It's a mostly re-usable two stage design, the Whiplash jet engine is decoupled when it outlives its usefulness. 

Launch on Year 1, day 236  or use an online transfer window planner to get a good departure to Duna.  

Climb to 17km keeping the nose less than 5 degrees above prograde for low drag, then level off and accelerate to 1300 m/s.  Up to this point I find it is best to keep SAS off and just use pitch trim (alt S and alt W) adjustments fine tune the nose angle.   Once you reach 1300,  add nose up pitch trim until the nose is 5 degrees above prograde.     Right click the whiplash engine and monitor it's thrust output.   When it falls below 30kN,   toggle SAS on and press Space Bar to stage.

After that, just maintain a nose angle of 5 degrees above prograde throughout the slow climb to space.   With SAS, the nose slowly rises over time, so you'll need to make periodic nose down corrections to prevent a draggy attitude.  Alternatively just take SAS off and hand fly it,  you'll find yourself gradually reducing nose up trim as the reaction wheel torque becomes more effective.  

Aerobraking - 17 to 20km PE into Duna.

Approach  -  use the map screen to avoid the higher ground.  No part of Duna is completely flat however.  

Configure - In the video above it appears i forgot to enable the landing lights on the gear legs.     RCS opens the service bay and activates the Vernor lifting thruster. 

Landing - gravity is much less than on Kerbin but so is lift, so be aware it takes much longer to arrest a descent.  Keep your descent rate below 5m/s when near the ground and look ahead to spot rising ground so you can start pitching up early.

It takes a long time for speed to bleed off but aim to land at 70-40 m/s.    Getting too slow means landing with either excessive pitch angle or high rate of descent.    Make sure your service bay is open and that RCS is on,  and keep a finger over the K key (RCS Translate UP).    Use it as a backup method of reducing descent rate for touchdown - if you're already pitched up at 10 degrees or more, use the vernor engine rather than risk a tailstrike.

 

Features -  in line clamp o tron, RTG power source, fly by wire hub for non-pilot kerbals, service bay.

 

Science?

I didn't put any instruments on this ship, and I appreciate that Spaceplanes are time consuming to modify and set traps for the unwary - everything tends to affect everything else.   The service bay contains an Oscar B tank, you can attach items to this part and know they will be shielded. 

The upper surface of the Oscar B has a deployable radiator module currently which isn't really necessary,  that should free up room for a few small instruments.

Edited January 9, 2017 by AeroGav

[TheKorbinjer]

Very nice craft! 

[eddiew]

50m/s touchdown is highly respectable, nicely done  

[AeroGav]

Incidentally, something that came up when discussing two-stage spaceplanes on this forum, was the objection, "Throwing away the jet engine forces you to land dead stick...   can be risky".

So, what if we misjudge the re-entry and are forced to land away from the runway,  in less than ideal terrain?  Will our Kerbals survive?   Only one way to find out 

I emptied the tanks and used infinite fuel cheat to simulate the empty, dead stick scenario.     It took a few goes to make the aircraft reach its stalling speed just as the flight path intersects the "adverse terrain", but it made for some entertaining video

Also tested was my mod of the Stearwing D45 (used to be a stock ship but was removed from game due to not flying properly after updates to the aero model),  since this also sheds its jet engines.

Low landing speed + crewed areas surrounded by crumple zone = win.