Useful Little Twin

I'm not getting back into the meat of aviation as quickly as I had intended, so I'm going to just pick up a manual and start reviewing systems. Eeeny-meeny-miney-moe gets me an airplane type I have flown a few times. I knew three people who owned these airplanes, and have flown four different aircraft of this type, including a couple of flight tests. It's a great little twin, a good IFR platform and the extra engine will actually take you somewhere, even with the aircraft well-loaded. There's no reason for me to obscure the make and model, except that it's fun and I know some of you will enjoy guessing.

Now I'm trying to decide which system is the most generic, so you don't all know it immediately. The trick is that even as I look at the index of the manual (it's a photocopy of my friend's POH) I smile remembering unique quirks of each system, and how they all interacted for good and for bad. I guess I'll start with the airframe.

It's an all-metal low-wing aluminum-skinned monoplane with semi-monocoque construction. (The semi-monocoque bit means that it has internal bracing but unlike early open-frame or canvas-covered aircraft, the skin is necessary to the structural integrity of the airplane). The fuselage is built in four pieces: nose cone, cabin, tail cone and an enamelled steel tube structure that runs from the tail cone to the nosewheel to hold it all together. The wings are rectangular, with a main centre spar plus a fore and aft spar, plus additional lateral stringers running through the ribs. The main spars are bolted together in the centre of the fuselage, but the rest of the wing does not carry through, but is bolted to the steel tube structure. The wings have a removable tip section, and five degrees of dihedral (the angle at which the wing slopes up from root to tip). The ratio of nose-to-tail length to wingspan is 0.81. That last is not a standard aircraft statistic, but I spoil guessing fun if I actually give the length and wingspan.

A detail in the manual is that the main wing spar is "stepped-down." I'm not certain how that is achieved. I assume that it's thicker at the wing roots than the wingtips through having less metal, but rather than being tapered ('cause they'd presumably just say "tapered") the gauge is otherwise quantized. I'll try to find out exactly how that works on a metal wing spar. On a wooden one it might be a reduction in the number of laminate layers. I don't often see aircraft wings with the skin removed, and when I do it's usually either an ancient hulk or a hobby plane under construction.