Just as there will always be an England, there will always be airplane buyers to whom nothing else matters but raw speed. Forget cabin size, payload, range or safety-lets just go faster than anyone else. And for these buyers, Mooney has just the airplane-the new Acclaim Type S, which appears to us to be a no-kidding 240-knot-plus airplane, making it the fastest single-engine piston currently in production-no arguments. Although speed is the antithesis of efficiency, the Type S can, nonetheless, deliver its blazing speed at relatively economical fuel burns. Mooney got into a marketing spat last year with the then Columbia Aircraft (now Cessna) about who had the fastest single. We think we settled this in our October 2007 report in which we found the Mooney Acclaim easily got past the Columbia in a two-way speed trial. If there was any doubt then, there isn’t now. At realistic cruise speeds and equivalent fuel flows, the Type S is solidly 20 knots faster than the Columbia and maybe a bit more than that over the Cirrus SR22 TN. Howd they do that? Mainly through a series of drag tweaks-flap hinge and gap treatments, new nosegear doors, redirection of cowl exit air, removal of the cabin entry step and an optimized prop. In our experience, speed mods like these often deliver elusive benefits. If one or two knots is promised, you may see a needle nudge or nothing at all. But Mooney seems to have genuinely delivered five knots over the 237-knot top speed claimed for the Acclaim. We never confirmed that number for the Acclaim, by the way, but the Columbia fell far enough short of the Mooneys performance to make the Acclaim the winner in our speed flyoff last year.
Go Fast
The Acclaim first appeared in late 2006, marketed as a high-performance, high-altitude cruiser for the discerning speed aficionado. Riding the coattails of Cirrus huge success with its Tornado Alley Turbo turbonormalized SR22, Mooney at first called the Acclaim turbonormalized. It really isn’t. It has a TSIO-550-GN that ground boosts slightly and, in any case, has the 7.5 to 1 compression ratio pistons Continental has used to build in detonation margins into turbocharged engines.
The Cirrus TN uses the IO-550 too, but with 8.5 to 1 pistons, which gives it a slight thermal efficiency edge. Mooneys version of this engine is derated to 280 HP, while the Cirrus generates the fully certified 310 HP.
With the Acclaim barely out the gate, Mooney chief engineer Dan Apel set to work looking for drag to lose, which he hunted down not in the wind tunnel but by computer numerical analysis and intuition.