Why are most IFR tourers like that?
Is it intentional or is it the result of some compromise elsewhere?
Just a guess, but being heavy in roll (obviously) makes it a more stabile platform. Being light in pitch is not going to send you into a spiral dive quite so quickly, and there is probably a limit to how heavy you want the pitch to be, if you also plan to land with a proper flare.
This is probably way too simple, but I thought the heaviness in roll was just simply due to bigger and longer wings (in most cases), and wih extra weight of the fuel.
The textbook objective for control harmony of any aircraft is ailerons lightest, pitch next, rudder heaviest. That assumes a modern aircraft (1950s up) with limited adverse yaw, needing limited rudder input. I think most going places aircraft get somewhere close to that objective, although I have limited time in any of them. Bonanzas and Comanches seemed pretty good to me, both have light roll control.
Two aircraft of this type that struck me as having heavy roll control were the Lancair IV kit plane, I think as a result of high airspeed plus short side stick, and the Diamond DA40, with its long sailplane-like wings. Long wings resist rolling because the act of rolling produces extra lift on the downward moving wing, due to higher AoA.
Peter,
Stay clear of flying in a Bonanza. It will ruin your outlook on other types. 
The “ideal” harmonisation of forces in controls is a ratio of 1:2:4 Roll:Pitch:Yaw
Just out of interest, how is pitch trim accomplished in the likes of the TB20? Is it simply a trimmable elevator, or a stabilator, or some combination?
Wing dihedral and a high wing improves the lateral stability of an aircraft. Most IFR tourers have one of those. Lateral stability means that it won’t roll that easy. I think lateral stability is convenient. When in turbulence you don’t want to keep correcting that wing when it goes up and down, so a little stability helps here. Wing sweep will also help the stability, but I don’t know any piston IFR tourers with those. On the contrary wing anhedral will make it less stable and will make the aircraft maneuverable. A good example of this is the Harrier.
Most small aircraft don’t have an enormous CG range, that should explain the light in pitch. You can of course make the pitch less light by moving the actual CG to the forward limit, but that will cost you some efficiency because the CG will move away from the centre of pressure, a larger tail force is now needed to compensate that.
On the contrary wing anhedral will make it less stable and will make the aircraft maneuverable. A good example of this is the Harrier
So this leads me to a question, I had asked it once but the answer did not convinced me.
The McDonald Douglas F4 Phantom has a dihedraled wing tips while the elevators are anhedraled, why?
Ben
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I don’t know the exact answer, must be some design issue. Wikipedia gives a hint:
The McDonnell Douglas F-4 Phantom II is one such example, unique among jet fighters for having dihedral wingtips. This was added after flight testing of the flat winged prototype showed the need to correct some unanticipated spiral mode instability – angling the wingtips, which were already designed to fold up for carrier operations, was a more practical solution than re-engineering the entire wing.
On the contrary wing anhedral will make it less stable and will make the aircraft maneuverable. A good example of this is the Harrier
Yes…high wing aircraft with a vertical couple on CG and CofP have a pendulum effect, hence the 152 having 1% of dihedral and the PA28 more like 4~5%. The BAe 146, Antonov also have anhedral. The Harrier’s anhedral very probably has been increased for maneuverability, but it is there in the first place because the aircraft is high wing. The circular fuselage may in theory be providing some coanda effect which also increases lateral stability as a wing drops.
