Still no idea how to protect the propeller without a plastic injection molded shroud. This is 1 area where a $1000 makerbot would come in handy. Just don't have a $130,000,000 government real estate loan to store it on.
Marcy-1 came in just as heavy as Vika 3. The surface mount board, integrated radio, & new name made no difference. She has a lot more wood than Vika 3 but is more balanced.http://www.rcgroups.com/forums/showthread.php?t=1044312Tried spinning up on a table to ensure stability before lifting off. Didn't have enough thrust to break free of the rod & spinning was unbalanced.
On the test stand for Her 1st revolutions.
Now a test stand video for posterity.Finally, a full power liftoff on the golf course led to this.
Then tried this to get more moment of inertia, unsuccessfully.
She's too unstable. They seem to require precise balance like a propeller. The balance requirement means she needs a 2nd PWM to translate horizontally.The Bladestar must not have used imbalance for translation but relied on the fact that its engines blew sideways. Another point for monocopters.Steve Morris did indeed make a spin copter & it required 2 PWM's for horizontal motion.Also, since the Bladestar appeared, all monocopters have switched from photodiodes to single axis magnetometers for position sensing, making the Marcy 1 aircraft board already busted. Magnetometers would be much easier than photodiodes but we figured their update rate was too slow. Not anymore.Instead of computing north, they just sense an arbitrary sine wave on a single axis magnetometer & rely on a hard coded point in the sine wave to determine where North is.So a silly spin copter is a much harder problem than first envisioned. Marcy 1 needs to be a monocopter.MONOCOPTER NOTESMonocopters use a "balance beam" to keep the angle of attack level. There are no photographs of the Lockheed Samurai but the low resolution video shows it probably uses a gyro instead of balance beam to control angle of attack.It also has a winglet to make it more stable.Predictably, the Goog has nothing on sizing a monocopter since there are no monocopter Adsense hits. Nothing to do but cut some wood.
That lasted about 4 hours. At full power she couldn't exit the launch rod. Shortened the launch rod enough for her to fall off & she went straight into the ground, probably due to insufficient RPM.Tried increasing angle of attack, grinding down the launch stand, & suspected imbalance was causing her to hang up on the launch stand.BALSA TERRORISM
Finally made a number of monocopter variations & a symmetric blade design just to see what would happen if we got her as balanced as possible. The monocopter is very hard to balance because of the limited payload room.The symmetric Marcy 1 finally worked. She lifted off the stand & into a stable hover before running out of room & crashing. Here's the video of the tests leading up to & including success.Balance is everything. A monocopter has to be perfectly balanced about the axis of rotation & the point the launch stand attaches to.
Note that Steve Morris also did this many years ago. He seemed to start over when switching from aerodynamics research to autonomous flight. Here's his monocopter.
Meanwhile, more Marcy-1 evolutions reduced her size, returned her to asymmetry & increased her RPM to achieve useful POV illusions someday, though her disk radius is fixed & limited by weight. The asymmetric wing is seen as important for achieving horizontal translation.That's basically a Bladestar for a lot more money & made by a strange country. The extremely fine traces on Marcy 1 are plagued by dirt. Don't be surprised if the radio appears dead after a landing.In addition to balance, a loss of control after exiting the launch stand can be caused by insufficient power. Move the motor farther from the CG to increase power. There is an optimum distance from the CG at which the motor provides maximum power yet the counterweight is not so far away that the wing is symmetric. The Goog has nothing on this.A test without the balance beam showed it is indeed required for a stable angle of attack. The Goog has nothing on the optimum balance beam size.Suspect Marcy-2 will be a large monocopter. A very large monocopter using a foam wing promises the longest hover time of any VTOL & complete control with only 1 PWM signal.SI4421 VS MRF49XA
Meanwhile, conversion from 72Mhz to 900Mhz isn't going so well. The Si4421 is pin compatible with the MRF49XA but seemingly not electrically compatible. Briefly got SPI out of it due to no particular code change & it went away. It's generating SPI but the PIC isn't receiving it.SPEAKING OF MARCY-1Going to try approaching the AIR FORCE HEROINE again so if we suddenly stop flying you'll know it was another DISASTER.
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