Spent a few nights and created a set of 3d print templates for cutting Apache24s' ribs and rudder. Share them at www.thingiverse.com/thing:6313844 Cheers! 😎
Thanks for sharing your recordings! Though one thing I am curious about is the imbalance of the planes wing where one is larger than the other. The blueprint shows that the left side of the plane is 18.3 cm and the right is 16.5. Im assuming this is for a tilt towards the left for the path to follow the circular path but could this be potentially to big of an offset and if not, how would you recommend trimming these flights (with respect to the circular motion)?
Yes, it is all about physics! :-) With a circular left-turn flight path, the right wing travels a longer distance than left wing does during the same amount of time. And therefore, right wing is moving faster. The "imbalance" wing panels is designed to have both wing halves generate the same amount of lift. Most SO designs have this imbalance built in, to keep wing level. The intent is to have all of the main wing's lift counters the weight, but not to help turning. I.e. Don't want the precious wing lift to tilt in and to have extra lift to work as centripetal force. Extra lift means extra drag. The amount of imbalance of the wing is influenced mainly by the radius of circle that the designer intends to fly with. During flight time, the turning radius is mainly determined by the effectiveness of left thrust, tail wing tilt (out) angle, and rudder angle. Since the first two factors were set at design/build-time, the main way to adjust turning radius on the field is on rudder angle. (If your airplane allows), changing/twisting the wash-in angle on the left wing could also change the radius. But that wash-in angle is another story all by itself. We will save it for some other day. Note, the diameter of propeller and nose-up flight attitude, i.e. P-factor, also affect how big or small the turning radius is. Apache24s is designed to fly slow with nose up. Trimming it to fly faster would result in a wider turning circle. Hope this helps. Feel free to ask any questions you might have. Happy to answer. :-) -AeroMartin
Hi, Venkata, Glad that you like this plane. I have put the Apache24s design plan and building instruction at Thingiverse.com: www.thingiverse.com/thing:6313844. Check it out there. Cheers! 🙂
Yes. My teams have tried dihedral wing designs every year in the past. Dihedral boosts lateral stability for sure, especially for outdoor and low-wing models (as well as many full-size airplanes.) Since Science Olympiad FLIGHT airplanes are always flying indoor, in calm air, I felt that kind of excessive stability is not necessary. With many hours of successful Apache24s and Apache23 (video link above) flights, the point is proven. If you have a chance, get rid of wingtip plates on your high-wing SO models, and see for yourselves. :-) Dihedral is not bad. Nor is wing tip plate. They have their place on others' designs. I simply made a different choice, for different design trade-offs. Actually, several of my Wright Stuff designs have dihedral on main wing, and, anhedral on tail wing. These airplanes flew like they were on rail and placed very well in Regionals and States every time. Besides, the Klingon-ship nose-high flying attitude was a great crowd pleaser. :-)
Welcome to Div. C. Those were impressive flights. Nice job in placing first at National. If I may make some suggestions. Although your propeller was turning slow, it is still a bit too fast, esp. at launch and climb out stage. It is not as efficient as the best I saw for Div. B. Check out the "Build Your Own Propellers" video I posted and see how slow a propeller can be. In addition, you may download the OpenSCAD propeller mold program that I posted at Thingiverse.com. With a 3d printer, you can build precise flaring propellers that are more suitable to your airplane. Four minutes and half should be a routine with your airplane under that high a ceiling. Five minute is possible. Another thing is, Although I saw the "blowing" turbulence in the video, it is not too excessive. I believe the problem lies in the dihedral you put into your airplane. Not that your airplane has not enough lateral stability and need more dihedral, (quite opposite, it has too much from that big a dihedral!), but your airplane's directional stability was being unfavorably impacted by that big a dihedral. Such a big dihedral creates too big a side area, ahead of CG. That is the problem. Any side area that is ahead of CG negates the directional stability that your vertical fins are trying to provide. In other words, your airplane was blown from the side, and was oscillating on the yaw axis, because of insufficient directional stability, not because of the lack of lateral stability. Try decrease dihedral, or get rid of dihedral completely ;-), your airplane will thank you with a few more seconds. :-)
