That's interesting. I hadn't thought of that. I have been doing some ciphering on control systems, but mainly for flapped stunters, where there's too much hinge moment. If you really want extra hinge moment, it's easy to get. Just use a bigger elevator chord: more like the Ringmaster than the Flite Streak. You could also use a smaller bellcrank or less bellcrank travel.
My comment above about "tail volume" is that it's an overly crude measure. If you can build the aft fuselage light and stiff enough, the more of that volume you get from tail moment arm and the less from tail area, the nicer your airplane will fly. You can fiddle with elevator chord and control ratios to get hinge moment to taste.
Ted, I'll send you my short monograph on hinge moment for your review (if I can figure it all out).
That's because we always listen to the pilots.
Howie,
I absolutely agree about the effects of elevator chord and feedback. It also, of course, brings the Netzeband wall more into the equation. I took more than half an inch of the trailing edge of the Doctor to obtain better response in the tops of the hourglass and other above 45 degree tricks. Also made the published version smaller than the original to make the use of commercially available three inch bellcranks a more viable option for the novice/beginner who goes to the hobby shop for his "stuff".
You're absolutely right about the relative "crudeness" of a lot of the terminology stunt fliers use as more or less "stunt gospel". Stunt gospel, of course, used to use the phrase "add weight to the tail if the airplane doesn't turn tight enough or to the nose if it turns to quickly" as the sum total of flight trimming options in probably hundreds of construction articles penned by then current "state of the art stars". Correct as far as it went but, of course, an incomplete document.
Like it or not, most stunt fliers (including yours truly) aren't classically trained in the arts of aerodynamics or the tools of higher math. The lack of those skills no doubt makes our search for the holy grail of the "perfect" stunter more of a hit and miss process than it might be for the dedicated practitioner who is fluent in them. That lack, of course, doesn't prevent the individual armed with "conceptual understanding" of aerodynamic principles and the willingness to "cut and try" from developing some pretty potent hardware. Or, perhaps, using that conceptual understanding to avoid going in directions that ultimately proved to be the "wrong way" despite the clear benefits determined by use of those skills (again our late, good friend Wild Bill and his talented sidekick, Bob Baron and the various "better stunters" they championed for both of their lifetimes.) The "conceptual" guy being aware of what is necessary to "win stuff" vice "be right"--understanding full well the monumental lack of logic expressed in the phrase!
For instance. In addition to the chord of the elevator and the mechanism geometry there are a variety of other physical attributes of the tail that can effect the discussion and which interrelate in other ways with the way a stunt ship responds and how much energy is applied to the control lines to make it do so. The aspect ratio of the tail and wing. Full span versus partial span flap, aerodynamic balance and/or in the case of some demon designers boost tabs on movable surfaces. The distance from the CG to the forces acting to redirect that CG while doing tricks, etc. You and Serge and Igor and Brett and Frank and a handful of others are capable of determining the how much...mostly in advance...but there are probably an equal number of guys that have conceptual understanding of the factors and inform their designs/experiments with it.
I think our all round library of "stunt gospel" has probably been enhanced by both in the last thirty or so years.
Ted
p.s. Assuming (always a tricky word, especially when applied to Howard) your comment about Boeing listening to pilots was not typed with your tongue firmly implanted in your cheek, I thank you and the rest of the Boeing engineers for your consideration. I've flown a bunch of Boeings (a -247 [for about 15 minutes], 720s, 727s, 757/767s and 747 100s, 200s, and 400s; my favorites being the 757 and the advanced 727--when it was light enough to perform like a loaded 757!) and with a single exception found them all to handle pretty much like gran prix sports cars whatever their size (including the '47-400, the best airplane for its mission I've ever been associated with). The one exception was the 767-200 on which the balance between roll and pitch and the clumsy fly by wire thrust levers made it feel like flying a bathtub half full of water. My meager exposure to the -300 model more or less proved the engineers agreed with me because it was a much pleasanter and predictable aircraft to hand fly. If a pilot could hand fly a C150 he could hand fly the Boeings...as long as he realized the instrument panel of the Boeing wasn't much bigger than the one in the 150 and that if he got the instrument panel where he wanted it to go the rest of the airplane (including all 875,000 pounds of the -400) would be right behind him when he parked it. Wonderful machines.
Topic: Tail Volume in Flapless Stunt Planes (Read 6584 times)