Flying the Bearhawk - Weight & Balance and Engine selection

Engine selection 

Probably the single largest factor affecting both weight and balance is engine selection. This is a case where bigger isn't always better, there's a definite compromise, particularly when operating in the back country.

The Bearhawk MTOW is stated as 2700lbs. I've tested mine to this weight. However I was concerned about damaging the airframe, so I use 2500lbs as a MTOW and if operating on short or rough airstrips I restrict it further to a maximum of 2300lbs. 

Effectively for a backcountry machine it becomes a very capable 2 person aircraft - or 3 persons in the right conditions. On a longer grass runway it's a capable 4 place machine.

IO540

My Bearhawk has an empty weight of 1500lbs (a very typical average weight with an IO540), and an empty CG of 8.3". That's a very forward CG (the 3 bladed prop contributes to this). The forward limit is 10.5", so with a pilot and reserve fuel, mine is right on the forward limit. This gives maximum utilization of the full CG range, and at a MTOW of 2500lbs this gives a useful load of 1000lbs.

An IO540 powered Bearhawk usually becomes limited by the maximum landing weight before it reaches the aft CG limit.

IO360

For a Bearhawk with an IO360, a typical empty weight is 1300 - 1350lbs (some are built even lighter, or much heavier). Anecdotal evidence suggests that the overall weight difference is often greater than the difference in engine weights.

That's roughly 150lbs (or more) lighter than mine. That aircraft will have a payload of 1150lbs using a MTOW of 2500lbs. Looking at it another way, it could use a MTOW for back country ops of 2300lbs and still have a payload of 950lbs. Or it could utilize the same payload that I restrict myself to for backcountry ops of 800lbs, and have a TOW of only 2150lbs. This gives lower takeoff and landing distances and is much easier on the airframe. Whichever way you look at it, there's a clear advantage.

The IO360 powered Bearhawk tends to be limited by the aft CG before it reaches maximum takeoff weight.

Take-off and Landing distances

IO360 

For the same payload and a lighter aircraft, the landing distance is shorter because the landing weight and therefore the stall speed are both less. The takeoff distance is very similar to an IO540 powered Bearhawk when at light weights.

IO540

The IO540 powered Bearhawk has an advantage particularly in the climb and particularly when hauling heavier weights. This is more noticeable at altitude. 

Center of Gravity

Having a large engine up front means when operating at light weights I am often near the forward limit of 10.5". Any time the Bearhawk CG is forward of 14", it tends to lose elevator authority when at approach speeds below 55kts. This can be mitigated by keeping the power on to provide airflow over the elevators.

With a lighter engine, the CG is naturally further aft so elevator authority doesn't tend to be an issue, but the aft CG limit can become a factor at higher loads.