RAH-66
The Commanche wasn't supposed to replace the Apache...it was supposed to replace the OH-58D Kiowa Warrior. The KW is an under-powered, under-armed updated version of the original OH-58A/C Kiowa. They took the basic OH-58, added a bunch of electronics and the MMS (Mast-Mounted Sight), a 4-bladed rotor system, and a couple weapons hardpoints, and added a modest power boost and made it into a semi-combat helicopter.
The sad thing is the Commanche was basically a finished design. All they had to do was complete the OT&E phase and put it in service. It was a much better platform for combat recon than the KW ever was. But under G.H.W. Bush and Clinton, the Commanche funding was drastically cut and the program limped along for about 15 years. Under Reagan, the -66 was supposed to enter service in late 1990s. Under Bush, it would enter service in early 2000s. Under Clinton, the service date was pushed back to about 2006. Under GW Bush, it was pushed back to 2008.
All that pushing back the time table saved a little money in the short term, but caused the overall program to skyrocket in the long run. In the end, we spent billions, fully developed the helicopter, and got nothing in return. We should have bought at least some to justify the cost of development.
Methinks this is also a little bit of calculated politics, since Sikorsky is in Connecticut, a notoriously democratic state, and close to home of Kerry. Bell Helicopter (who built and supplies parts for the OH-58D) is based in Ft. Worth, TX.
But the #1 reason the program was axed was short-sightedness on behalf of our elected schmoes on "the Hill". Just like the tanker lease deal, all they looked at and cared about was the bottom line.