Hi Ron
The original profile version of the Imitation had a very thick stab shown on the plan but that was modified later on. When we were consulting with Ted during the period of getting the profile Imitation kit done, It was decided to reduce the thickness to make the stab 3/8" thick and that will carry over with the full fuselage version we will be coming out with.
Mike
FYI,
The original Imitation did, in fact, have a very thick completely airfoiled stab/elevator...likely somewhere in the 15% thickness range. Over several years I experimented with various "sections" for tails triggered by Bob Gialdini's comment in a constructions article that stated (appox) "...Remember, the tail is a lifting surface, too and, like the wing, must be thick enough to do it's job...".
The 1986 Nats winning Intimidation was the first of my very thick tails and the Imitation and Excitation were similar but slightly thinner sections. these were followed up by test ships with tails as thin as 1/8" on a variety of competitive stunters that "may" have nudged the VSC rule book as they showed up on airplanes flown at that event. The test on such thin sections was driven in part by the very successful box stock Veco Chief I flew at two back to back VSCs which came stock with such a thin section.
The bottom line was that, although I continue to believe the original Imitation was the best design I've ever done in terms of ease of reproducing competitive patterns, I didn't feet its excellence could be attributed to any measureable degree to the thick section (The Intimidation mentioned above, for instance, was "not" my favorite airplane despite its respectable competitive record). In discussions with Mike re his kit I suggested and he agreed that the difficulty for less than expert modelers to reproduce the thick airfoiled stab accurately any benefit that might have resulted was, in our opinions, not worth the risk of poorly contoured tails in those modelers' aircraft. I did suggest, however, that the thickness of the stab/elev be increased to 3/8" and retain a "semi" airfoiled section via tapered elevators and a leading edge preferably shaped in "airfoil" fashion with a sharp entry (don't recall for sure whether that last was implemented in the kit).
Further FWIW comments. I believe the primary design enhancements that resulted in a successful (and still entirely competitive) design were the longer tail moment arm, larger tail area relative to the wing, the capability to utilize further aft CGs for enhanced maneuverability with less effort and greater stability and the smaller chord flaps (to reduce hinge loading and negative pitching moments from their deflection and, thus reducing, input effort on the part of the pilot). Only the latter, narrow chord flaps, do I remotely deem to be hatched in my own noggin. Pretty hard to declare oneself an innovative designer when you can pick up my old Veco Chief and fly competitive patterns 65 or so years later!
Hmmmm. As I look at that Chief hanging on the wall of my office right now I note that the flap chord has a lot more in common with the Imitation than it does with the chord on much more modern "big flaps for the lift needed for tight corners" designs.
Scratch the hatched in my own noggin comment above.
Ted
Addendum: RE the change in the stab/elev thickness addressed above. The increase to 3/8" overall thickness I suggested to Mike was solely due to concerns over a stab/elev of that much area having only modest resistance to flexing under load...especially if covered with monokote or similar. The additional thickness of the ultimate stab was almost exclusively aimed at remedying that potential. The thicker airfoil shape of the original wasn't of much concern to me due to the curved sections and warren trussing. Also worth noting was my continued (then and now) preference for reduced elevator chord re the stab (55/45-60/40) to minimize control loading.
Topic: A true full fuselage IMITATION KIT is on the way (Thank you Randy and Brett) (Read 8197 times)