RCU Forums - View Single Post - Pattern airframe design theory and discussion
Old 01-24-2005 | 01:50 AM
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David Gibbs
 
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From: Camberwell, AUSTRALIA
Default RE: Pattern airframe design theory and discussion

Wow -- Lots to digest in here!

I sense a reasonable understanding of horizontal and vertical flight -- and the compromises across thrust line, wing and stab incidence and relative heights. This seems to be governed by centre of lift versus centre of drag etc., and the moments at work can be reasonably easily drawn. Don't get me wrong, I am not suggesting it is easy -- just a little easier to get our heads around -- there is still a lot unknown.

The one I can't construct a mental picture of is the interaction between rudder and wing dihedral - in flat flight but also in knife-edge. I gather the rudder hinge line plays an important role on drag when the rudder is deflected -- and hence the angle of the hinge line and the portion above versus below the stab impacts pull towards belly or canopy in knifeedge, in addition to the combination of thrust line and wing/stab incidences. The centre of lift must have something to do with the aerodynamics of the fuz on its side (which I assume could be quite different to the wing in horizontal flight, and quite different across the thinner models of 5+ years back and the bulkier ones today). But what are the dynamics of the interaction between the rudder and dihedral that lead to adverse and proverse roll on rudder? Any ideas (or a full, simple explanation!!) appreciated.