GreggyPoo
Senior Heliman
Location: Where it rains all the time
| The big day - Progress reportHmmmmmm – Not the best progress today 
Here’s how it went –
Before anything else, I copied the existing radio setup from one 8103 to another – I wanted to be able to tweak the setup as necessary and didn’t want to lose my existing setup.
First thing I did to ready the Hummingbird was to flip the blades over and reverse the direction of the main rotor, by reversing the polarity of the main motor – While I was at it, I also flipped the paddles over and made sure that the rotor was balanced.
Next step was to get the tail rotor reversed – Same process as with the main rotor – Reverse the blades and also reverse the polarity of the motor. Since there are no pins on the reverse side of the tail rotor blades to mount to the secondary gear, I used some nylon string to hold it against the secondary gear – To prevent the reversed blades from coming in contact with the tail motor hub, I used a small section of silicone tubing between the gear and the tail blades.
Since the rotors are running in a reverse direction, it was also necessary to reverse the gyro direction. Since I’m using the stock century gyro, this is accomplished by mounting it upside down – Since this was temporary, I decided that rather than remounting the entire gyro, I just popped the case open and mounted the internal component temporarily at the rear of the frame with some servo tape.
For initial trimming and trials, I decided that I would tether the hummingbird from the ceiling. I had some rubber bands handy, so I used those. Someone had mentioned that this wouldn’t work – Well guess what – It didn’t! 
It was a step in the right direction though, since it simplified what I attempted next –
HAND LAUNCHING!!! 
OK – Results? Not so good
If you remember, I had been concerned that the Hummingbird wouldn’t have enough cyclic control to counteract the weight and pendulum effect of the fuselage when it was inverted – This turned out to be exactly the case. In an inverted orientation and with the rotor now turning counterclockwise, the natural rotor tilt was now about 10 degrees low on the right side when viewed from the rear. In order to try to counteract the extreme tendency to roll right, I input maximum sub-trim to left aileron. Unfortunately the weight of the body, combined with the rotor tilt was too much to counteract with aileron control and the tendency to roll hard right couldn’t be overcome.
As promised, I did get a video demonstrating both launch methods I attempted, but like I said, this just didn’t work out. I kept the video short and small so bandwidth isn’t wasted, but if you’re curious, it’s at the bottom of my gallery if you’re compelled to have a look (I guess it is entertaining) 
http://www.runryder.com/helicopter/gallery/13347/
It’s below the section titled “A really stupid Project - The inverted Hummingbird”
Sorry guys – I tried. 
Greg |
