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Description
First of the Combined Nuclear-propulsion Aircraft series, the Apex is single-stage-to-Mun and return aircraft with fully functional docking suite. Capable of reaching 100x100km LKO with 3.25km/s of dV left. Intended to operate on Mun; current variant designation is D.
Ascent profile
- Rotate at ~70m/s.
- Pitch up & maintain 10 deg.
- At altitude of 20km, press 3 to ignite LV-N.
- At altitude of 25km, switch RAPIER mode and pitch up & maintain 20 deg.
- At altitude of 40km, pitch down to prograde.
- Keep burning until desired apoapsis is met.
- Deploy solar panels and circularize at AP.
Specifications
- Stock?: Yes
- Version: 1.0~1.0.5
- Type: Single-stage-to-Mun
- Crew: 1 (remote operation capable)
- Operational weight: 33.305t
- Empty weight: 14.805t
- Payload capacity: N/A
- Propulsion: 2x RAPIER, 1x LV-N
- Size: 16.4m x 11.9m x 2.7m
- Part count: 67
Development history
[Origin of CNA series]
The Combined Nuclear-propulsion Aircraft series aims to create SSTOs with pre-1.0 performance.
With (personally) welcomed nerfing of turb-OP-jets, SSTOs of post-1.0 era have generally inferior performance. Now, creating a SSTO with at least 2km/s of dV on orbit must include nuclear propulsion system. But this presents another problem as LV-N has terrible TWR. This rules out high performance, LF-only SSTOs from emerging. To deal with a wide gap of safe transition speed - 200~300m/s between high TWR (RAPIER) to low TWR (nuclear) - one must use RAPIER’s closed cycle mode for a while. This resulted in the above-mentioned naming of my series.
All CNA series crafts have ascent profile embedded into in-game craft description for convenience.
[CNA-1 Apex]
As the first craft in the series, I decided to push the limit and create single-stage-to-Mun aircraft but also determined to maintain full docking suite. This decision was based on my observation that many SSTMs on the forum lack active docking capacity.
Based on YF-23’s wing layout, the Apex has standard ‘2R-1N’ engine layout. With 3.25km/s of dV on orbit, you could go anywhere as long as dV permits. While initial maneuverability with full tanks are not that much satisfactory, it can pull out +80 deg AoA at reentry, a must-have feature for intra-Kerbin system SSTO.
Current variant, D, finally dispenses the forward fuel storage that acted as COM balance and hampered performance. It also adds vertical landing gears, something that Mun landing operation desperately asked for.
Trivia
I impose myself a strict SSTO usage doctrine; SSTOs should not embark on a mission to other bodies alone (except for Mun and Minmus), and interplanetary missions using SSTOs must include mothership(s) to dock to. Feel free to use the CNA series as interplanetary SSTO, but I cannot guarantee your mission’s success.
