Editing CRV7 (section)

==Engine development==

The [[aluminium]]-based fuel in the C-14 engine generated considerable amounts of smoke. While suitable for high-speed aircraft that quickly clear the plume, it is not suitable for slower aircraft and [[helicopters]] which would be flying in the smoke for some period of time. This problem led to the development of the RLU-5002/B (C-15) engine, which did not include aluminium and produced considerably less smoke, with a slightly lower impulse of 2,185&nbsp;lbf·s (9.7&nbsp;kN·s).<ref name=fixed/> The original C-15 used a tail-mounted igniter that was ejected by the rocket when it was fired. In some cases the igniter would hit the aircraft, causing minor damage. To address this, the RLU-5002A/B (HEPI) was introduced, with a "Head-End Permanent Igniter" that is not ejected on launch.

The latest C-17 and C-18 engines for helicopter use offer somewhat lower impulse at 1,905&nbsp;lbf·s (8.5&nbsp;kN·s), but with almost no smoke at all.<ref name=rotary>''Rotary''</ref>