KSP 1.1
The S5 Arrow is a medium sized SSTO (like the S2 Athena) designed to carry four kerbals into a (maximum) orbit of 400 km. The craft is easy to fly and quite forgiving. It is equiped with droptanks (not necessary, but provide some extra fuel for a return to Kerbin), has a service bay with radiators and solar panels, but can also be used to carry some equipment into orbit.
Take-off speed is 100 m/s
Landing speed is 80 m/s
Pitch while ascending to orbit is a recommended 15 degrees, at 22000 m, switch RAPIER mode with custom key 1 and close air-intakes with custom key 2.
Other craft in the S-series
S4 Apollo (taken out of service as per 1.1, it's superseded by the S5 Arrow)
S6 Axe (due to come online later)
S9 Beluga (due to come online later)