Ground station packed in. Battery sensor calibrated.
This design did not achieve horizontal control. The pitch oscillation
from not having enough balance beam inertia offset any horizontal force.
This redesign did achieve 2 horizontal changes of direction using only
throttle modulation. Unfortunately she threw a propeller &
disintegrated upon crashing.
Marcy-1 was already very prone to throwing propellers, her 5300kV motor
seemingly at the limit of Chinese plastic. We have a 4' monocopter
planned for extremely long duration hovers with normal RPM.
There it is. XYZ positioning using only throttle on the Marcy 1 vehicle.
Unfortunately not enough authority to move upwind, so we only got
crosswind translations & a slower downwind drift than if cyclic was
As Mike Bakula recommended, used raw magnetometer output & detected when
the halfway point in the waveform was crossed. Much better than using
derivatives like MIT since the derivatives are very noisy.
Very important to have the balance beam loaded as much as humanly
possible to prevent pitch oscillation. Having the motor & battery on
the balance beam is the easiest way to load it. She did indeed bank in
the direction of the translation from throttle alone.
An aileron servo would do better against the wind but it would be heavy,
expensive, & wear out fast. No way a servo would cycle 6x a second for
very long. If you're gonna use 2 PWM, there's no point in a monocopter
anyways but it's probably unavoidable for any long duration, outdoor
Finally got a flight in no wind & drizzle & she was easily controllable
using only 1 PWM. She was very sensitive to breezes.
1 problem was power level changes when applying cyclic which we actually
learned to handle. Greatest horizontal thrust comes from gliding her
when applying cyclic. You can stall the motor this way so she just
applies thrust in 1 direction yet stays in the air. Greatest vertical
thrust comes from releasing cyclic. Power management on a monocopter is
a new artform.
The mane problem was broken propellers after 6 minutes. That's right.
The GWS 3x2's are just not strong enough to provide hovering power.
Marcy 1 is perfect in every way but dead without a stronger propeller.
Ideas range from griding them down to 2.5x2 & using 3x3 if the weather
3x2 ground into a 2.5x2
Getting sonar working on a new flight computer & new radio is never
easy. The mane problem is actually the microcontrollers & tools. Every
new microcontroller has a different register set. If you want SPI,
magnetometer, & 3k of RAM that means capture compare & analog need to be
Also, the MRF49XA takes so much more CPU time to service than the XBee,
sonar had to go on a dedicated USB device, making it more expensive to
use 8 bit PICs than 32 bit ARMs.
3 years ago ARMs were $10 & really tough to solder. Now they're $2 &
easily soldered. PICs are only still around because of code reuse
though ARMs need a lot more pins for programming.
Building a 100Mhz computer from scratch using an ARM has always been
alluring, but the only motivation now would be going back to embedded
autopilots or a huge price advantage with ARMs.
The trick with sonar is to synchronize the clocks on the ground station
& aircraft. Vika 2 did it by sending 1 beacon to the ground station &
aircraft simultaneously. Marcy 1 doesn't have sonar on the same USB
port so there's a significant rewrite already.
The complete Marcy 1 sonar guided kit, applying all the sonar knowledge
gained from Vika 2.
The standalone sonar board is the simplest possible.
Now more views of the machine with 3x2's & loaded balance beam.
Sonar installed, magnetometer in the stock & this thing which tells
time. Wow that sounds neat.
Making the sonar crash resistant is going to require a new fuselage.
Aren't you glad you didn't need to solder this. This is standard for
Chinese toys though not Air Force grade except for the name.