akoch wrote:Sure:
Vso=36 KIAS - check
Large fowler flaps (45 degrees LND) - check
Absence of major AD's (not a single one on the airframe) - check
No known frame failures in flight - check
Simplicity -check
Utility - check
in addition - 5.5GPH for 140KTAS cruise; Vne=168KIAS; rate of climb over 1000fpm
I'll assume in this case you're describing a DA-40, but your numbers are significantly out. While the 140kts is possible, to achieve that you're usually looking at a close to 9.5 - 10 GPH burn to do it. While I suppose to some its fun to see bigger numbers on your airspeed indication, the DA-40 readily shrinks your range circle considerably with that power setting on your neat little moving map display. We typically cruised at about 130 which made the beasts a little less thirsty at around 7 GPH, but substantially increased your zero wind range. Either way, despite going slower the contemporary C-172 R and S models would grossly out range the DA-40, and definitely out haul them. Speaking of Utility the DA-40 essentailly became a two person airplane with a full load of fuel. With me and another guy who was somewhat smaller so we averaged out to two 180 lbs pilots we had a whopping 35lbs left extra for bags. Lucky for me I travel light and don't carry around one of those giant flight bags. Often people are under the illusion that composite aircraft have lighter airframes than similar aluminum ones, but that's far from the truth, especially when you see how much steel underlies the DA-40 which accounts for its whopping empty airframe weights of around 1750lbs - its almost comparable to 182 numbers, and about a hundred pounds heavier than most of the 172s. This really eats into the aircraft's utility, since any use of he rear seats really eats into the aircraft's range. In all, despite vaunted claims, its overall performance was rather disappointing. Nice plane though, but not a useful one.
Incidentally, one should also note that none of the strutted Cessna models have ever had in flight break ups either (which is in stark contrast to the record of their "unstrutted" classic models the 177 and the 210).
The point is that while most of the new designs beat the ol' Cessna in some facet, they are never as good of all rounders. Even Cessna figured out they really couldn't mess with it back in the day, see why the Cardinal didn't become a success.
Colonel Sanders wrote:2) 1980 aluminum airframe could be replaced by composite
with the advantage of less weight but at a higher cost. It is
interesting that the homebuilders, who have absolutely no
paperwork hurdles, have chosen aluminum over composite -
see RV-X
Again, this would be true if we were talking about carbon fiber, but as of yet I most out there use glass fiber which main component is silicon. Consulting the
periodic table its not hard to see why aluminum is the choice material, forming complex shapes aside, aluminum airframes are always going to be lighter, a prime consideration with aircraft design. Carbon of course would be lighter, but if I was to project what an entirely carbon fiber airplane would cost from what carbon fiber fairings for my motorcycle cost vs plastic ones, your typical 4 seat piston airplane would crack the million dollar mark.
The big bonus that composite (glass fiber planes have is the ability to make nice drag reducing shapes, so its only really worth it if you're making something that goes fast as its prime consideration a la the Rutan designs or going all the way with speed performance above all other considerations like the Columbia/Corvalis, Lancairs and to a bit lesser degree the Cirrus (which like the Diamond is too much of a compromise so it doesn't take the full advantage of what can be achieved with the composite - the grossly heavy airframe really makes it somewhat of a less utility airplane than the sales brochure would have you believe).