Now why the heck did they do that? Are they trying to allow Ikara props? Anyway, DON'T expect that to be a clarification for Nationals, even if held in Illinois. I mean, it could happen, but not if I...
baker wrote:Jander, with all due respect, you seem to be one in the know of this event...how about shareing your experiances with these...designs, time, height, does it fly around the room..you know stuff..
Ohh I HATE questions like this. Absolutely open ended. Tempts me to say everything so I end up saying nothing after spending an hour writing a long note that I'm not satsified with. OK, lets try a shorter answer and you guys throw out more specific questions.
BTW, you give me WAY too much credit. I actually have very little experience with helicopters, especially compared to Wright Stuff. Part of the attraction of this event is that while the skills of WS mentors are still valuable, few, if any, have the same level of expertise as they have with WS. Leaving more for the students to discover!
But, I'll briefly share my observations and some truisms.
First, what part about weight being CRITICAL to Wright Stuff didn't you get, and why don't you think it applies to helicopters? In building real, working flying machines the first, most important thing is to minimize weight. And so is the second and third! You can get a brick to fly, but you better have a LOT of power, and don't expect it to fly well! The rules require, what, 4.0 gms minimum weight. Your copters MUST weigh very close to 4.0, certainly less than 5.0 gms to be successful.
Second, think of the rotor and blades as a wing. Bigger rotors and bigger blades will give more lift, allowing the rotors to turn slower to lift that 4.0 gm, allowing longer flights. Now, there is a limit on blade size for a number of reasons that tempted me to write an encyclopedia, but that starts getting beyond my expertise fast. As a practical matter you want your rotor diameter to be the maximum allowed, like you want a WS wing to be the maximum span allowed. You probably want widish blades, and possibly more than two for your rotor, but the true optimum is not clear to me at least. I've seen two-bladed rotors with tip chords on the order of 10 to 20 percent of chord diameter seem to fly pretty well. I can't say they are optimum.
Third, the top rotor starts the air moving down, the second is in that moving stream and has to move it faster, the bottom rotor will work best if slightly higher pitch than the top. Not sure how much is best.
Fourth flight pattern. Ceiling walkers fly straight up and descend straight down. I suspect they'll 'cruise' if you get the rubber/rotor combination just right and have enough height to fly in, but haven't had enough experience to get there. This matching will probably be more critical than Wright Stuff. I also suspect winding to torque will be even more critical with these copters. They aren't real stable so if they hit the ceiling so the blades flip them around, the behavior can be exciting. Consider adding a stick to the top rotor shaft to hit the ceiling first so it can spin on that point and keep the blades from hitting the ceiling. I've seen copters with this feature fly to the ceiling and just sit there twirly till the rubber wound down and they descended.
Fifth, construction. With weight so important, expect to need and use building skills very similar to Wright Stuff and the best bridges. You have to build light and strong and straight with great control. You have to build to a specific weight. You have to create an intended shape.
Some broad hints, hope that helps, if not try more specific questions. And for a while, don't expect the degree of expert help you have available for Wright Stuff. Again, that's one of the reasons for trying to introduce this event.
Jeff Anderson
Livonia, MI
2008 NY BLG Champ