The Pilatus PC-8D Twin Porter is a particularly fun one.
Based, of course, on the PC-6 Porter, the sole example was built in 1967 and flew until 1969, when it was scrapped.
But during those two years, it was the subject of much study and testing, but the single-engine performance was insufficient for certification.
Based on how closely the engines were positioned to centerline, and also on the greatly enlarged vertical stabilizer shown here in the last set of photos, I suspect the lack of performance was presumably due to insufficient power as opposed to insufficient control.
In the end, the single-engine PC-6 Turbo Porter offered far greater efficiency and economy, and the single PT-6 was also probably a more reliable arrangement than the two IO-540 Lycomings, particularly when flying into and out of high altitude airports.
Of course, that begs the question of why Pilatus never introduced a Twin Turbo Porter, equipped with two PT-6s.
Evidently, not enough demand existed for such a beast. But it's fun to imagine how it would have looked.
Presumably, the lighter PT-6s would have to have been positioned quite a bit further forward, much like the Grumman G-21A Turbo Goose.
The cockpit visibility would have been horrendous, but the performance would have been fantastic. ⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀ ⠀ ⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀ #avgeek #aircraft #aviation #stol #bushplane #bushpilot #overland #pilatus #pilatusporter #tailwheel #taildragger #lycoming #pt6nation #cessnateur