A few weeks ago, I started laying out the V-tail airfoils on AutoCAD. The non-moving parts are not vertical stabilizers, and they aren't horizontal either.. they are diagonal stabilizers, right? So the diagonal stab. area was increased somewhat from the stock Moni config. to add the extra yaw and pitch stability needed for the span extensions. The hinged area (ruddervators) didn't change much, because it seems that pitch control authority is reportedly ample (even a bit "touchy"), but extra yaw control authority will be added via the 1-2 sq.ft. mini-rudder (the bottom part of the Y-tail). The extra semi-span distance was added to get the pitot tube out of the wider prop wash, since I plan to use a 40" diameter direct-drive prop with a lower-revving (~3,600 RPM) 4-stroke engine. The overall dimension changes on the diagonal tail surfaces are:
-semi-span increased from 35.5" to 40"
-root chord increased from 23.5" to 25.5"
-tip chord decreased from 15" to 13.6"
-hinged ruddervator area approximately unchanged
-forward spar sweep decreased from 13 to 8 degrees
-less swept leading edge, and forward swept trailing edge
After drilling many rivets and removing 7.6 pounds of crumpled aluminum V-tail, I sawed off the extra length of 1.25 x 0.125 aluminum bar for the aft spars so that about 3.5 inches of it was extending outward from the fuselage, same as the forward spar. I bent the forward spar straps forward to accommodate the less-swept leading edge, while keeping the aft spar perpendicular to aircraft centerline... my target weight goal for the Y-tail is under 4 pounds... a savings of at least 3.6 pounds.. that may not sound like much, but it's significant in that the weight of the whole aircraft would drop by at least 14.4 pounds.. It has other advantages too.
Next post: Composite V-tail fabrication and more design stuff.
No comments:
Post a Comment