I've been going back and reading threads, seeing how in the last year or so there has been a move toward smaller engines in certain "size categories" of aircraft.

For instance, flyers are finding that 50cc engines easily pull around 16-18 lbs planes, the 100 cc motors can handle 40% planes, and even 35-40 cc engines are "normal" on 80-85" planes weighing 13-15 lbs.

The planes have been getting steadily lighter, now being about 25% lighter than just 3 years ago, and the power output (for an engines weight) has increased tremendously over the last 5-6 years. So, it begs to ask, what size engine IS appropriate for a plane these days? So, here's the question/subject I'd like to bring forward. . .

If you had the money to do it all again (build your current plane, or another "favorite" you had in the past) would a re-think of the engine/airframe combination yield a better flying plane for the same money? Could you have actually SAVED money by going to a smaller/lighter engine and modifying the airframe slightly (single in place of a twin, smaller displacement twin for less money, etc.), and let's have some thoughts on "can it be built TOO light" when the total engine/airframe combination is considered.

In my own personal experience, I've found that my 40 lbs 40% CA330sx, with a 3W150 on the nose, is NO match for my radically lightened 28 lbs 40% CA330 with a BME110 on the nose. Both planes came from the same molds, but the performance difference is startling. The 40lbs plane flies very well, but even the simplest pull-up results in the plane "sliding" through the pull, instead of just changing directions. The same holds true for just about any maneuver, and though it is a very good flying plane, it's just no match for it's 30% lighter sibling. The ligher plane is crisper, more reactive, damps out oscillations faster, and accelerates/decelerates quicker. It also required a lower servo count and less expensive hardware to finish it out.

So, let's hear YOUR thoughts on how far this is going to go, and what is practical and do-able NOW.