The Yakovlev Yak-38.
Born out of the same sudden fever dream obsession with vertical take-off and landing (VTOL) aircraft that gave us the Harrier, the Yak-38 was Not Very Good at being a VTOL aircraft- or good at being an aircraft, for that matter. See, the most important thing in a VTOL aircraft is being fairly light- you need enough downward thrust to push it into the air after all- and after that, what matters is stability, to make the transition in and out of vertical flight smooth and safe.
The Yak-38 was neither.
Unlike the Harrier, which used a clever system of ducts to literally angle the exhaust from its single, large engine downwards, the Yak had an extra two engines that existed only to provide downwards thrust, then were dead weight the rest of the time. This gave it very low flight endurance since you traded fuel space for that, it was slow, clunky, and unmaneuverable, and most damningly, because of its low total thrust, it couldn’t actually lift off at all at higher altitudes and thinner air- such as the USSR discovered when they were deployed to Afghanistan. This meant the Yak-38 frequently went into combat with even fewer weapons on the pylons than its already pitiful maximum weapon load theoretically allowed for.
Oh, but it gets worse.
See, remember how I said the second most important thing in a VTOL aircraft is “stability”? Well, the Yak-38 was not stable- not at all. That pencil-thin fuselage and its clunky multi-engine VTOL system meant it was unresponsive and dangerously roll-prone in transition to vertical flight, and was so dangerous in this mode that it was equipped with a wholly automated (and unreliable) landing system, one which included an automatic ejection system if it detected the plane rolled past something like 30 degrees to one side or another, at which point it would eject the pilot, as it was virtually impossible to recover at that point. This most certainly saved countless lives, as more Yak-38s were lost to accidents than they ever were in combat.
It was an absolute disaster of an aircraft, and I love it to bits.
