The Lockheed Martin VH-71
From the aeronautical point of view, this was designed well. Augusta Westland and Lockheed Martin developed and marketed it in the U.S. in 2002. It was so impressive that the Marine Carps opted to use it for Presidential transport in 2005. However, the contract for it went from $6.1 billion to $11.2 billion four years after that. The asking price was simply too much.
The Lockheed Martin VH-71
The Bristol 188
Regardless of the industry, it is always important to at least level with your competitors. Chuck Yeager managed to break the sound barrier with the Bell X-1 in 1947, which led other air faces to work on research planes of their own. The British made the Bristol 188, but the fuel tank always leaked when the plane was midflight. On top of that, the plane could not take off until it reached 300 mph.
The Bristol 188