Early flight-testing of the Python was carried out using the [[Avro Lancaster|Lancaster B.1 (FE)]] ''[[United Kingdom military aircraft serials|TW911]]'' and the [[Avro Lincoln|Lincoln B.2]] ''RE339/G'',: in each aircraft havingPythons replaced the two outboard [[Rolls-Royce Merlin]]s replaced by Pythons.
Lincoln B.2 ''RF403'' also had two Pythons similarly installed and was used for high-altitude bombing trials at [[Woomera, South Australia]], the Pythons being used to increase the [[Flight ceiling|height]] from which tests could be carried out. These trials were principally of the ballistic casings for the [[Blue Danube (nuclear weapon)|Blue Danube]] [[Nuclear weapon|atomic weapon]],: therethe beingLincoln atwas the timeonly no other suitableavailable aircraft available that could accommodate the large weapon casing, measuring 62 inches diameter x {{convert|24|ft|m}} in length,. andThe carryPythons were itfitted to increase the [[Flight ceiling|height]] requiredfrom which tests could be carried out. Maximum release height and speed for the first eleven tests was 275 mph and {{convert|34,783|ft|m|abbr=on}} with a bombing error of 61 ft.<ref>The National Archives, London, file ES 1/44 E4C Appendix 3 page 1.</ref>
