bitPimps.lixlink.com

beanoman wrote:err... Did all you guys get it from RS?

Also remember, NOTHING else is going to fly as easy as one of these. They were designed by a micro heli pro, probly the singular best at micro single rotor helis. He also designed the piccolo helis that maxx meantioned.

SuperFly wrote:
You know how if you have a fetted car of any kind, how when your battery is about to die you might lose steering before you lose the motor? I could be wrong, but I think that's what happens with these choppers. When you don't get a good charge, the main rotor sucks the power more efficiently, and the tail rotor (which controls rotation) suffers.

Good Design!

Microflite, I do not have one in my hand, but judging from the photos and flight descriptions I can offer the following:

1. In a heli NEGATIVE coning angle is stable; the "natural" positive coning angle caused by the lifting rise of the blades is unstable. Only on a tiny heli is it possible to force and enforce this "drooping blade" thing in flight. Since the airflow on a heli is from top to bottom, the OPPOSITE of fixed wing aircraft, in forward flight, for ex., the front half of a negatively coned rotor "sees" more air and thus the front half of the rotor pitches up to stabilize the heli and tries to decrease the forward action. In a conventional positively coned rotor, the BACK half of the rotor pitches up in fast forward flight, trying to nosedive the heli. Every full-ftn. heli pilot has experienced this, and it is why most full size copters have horizontal stabilizers with fixed negative AoA to help push the tail boom down in fast forward flight (the Black Hawk has one which changes AoA for landing and slow flight). The PiccoZ is thus more or less inherently stable as a result of its negative coning angle. This is offset by the fact that the C.G. is below the center of lift, as it is in 99% of helis (except some toys and Stan Hiller's "Flying Platforms"), which is an UNstabilizing influence in a body rotating in a gravitational field! In contrast, top-heavy tops and hardboiled eggs ARE stable when spinning.

2. The upper control rotor on the PiccoZ has a positive coning angle and is thus clearly unstable. In forward flight (induced by noseweight and the landing skid [see 3. below]) an upper rotor blade will experience max lift airflow when it is on the left side turning into the airflow but due to precession the effect will not show up until that blade is facing forward. Further, the upper rotor disc has a positive coning angle which creates an additional lifting airflow on the blades in the front of the upper disc in forward flight (inside-out umbrella blown back by the wind), showing up at 90 degrees clockwise from the front due to precession. So the combined max lifting airflow on the upper rotor blade is on the right at the combination of the blade and disc lift forces of the averaged (0 + 90)/2 = 45 degrees from the front clockwise viewed from the top. Since the force from the positive coning angle is probably less than that caused by the increased airspeed on the left, the actual force is likely at 40 degrees. This force on the blade lifts the blade chord around the radial front pitch axis, DECREASING its pitch! At that point the lower blade, which is slightly behind the upper blade on the right side (lets say 10 degrees) will then have its pitch decreased by the upper one and it will APPLY this MINIMIZING lift force 90 degrees farther, or lets say at (40 - 10 + 90 =) 120 degrees (or less). So the upper rotor should apply a corrective negative lift force via the lower rotor to the right and slightly rearward in response to forward flight impetus. In other words, this heli would resist increasing forward velocity (from noseweight, landing-gear vane or sudden "headwind"), by trying to slow down AND turn right. Since we know that tail-rotors "eat up" a lot of power (also mechanically on full-size and non-electric model helis), it would appear that this set-up allows the tail rotor to require less power for right turns (since it would otherwise have to greatly increase its output to further counter the counterclockwise torque to turn the body right). Seems like an elegant design solution to me!

3. The downwash hits the landing skid, which may be thought of as an inverted wing (airflow coming from top!). This wing is tilted and produces a REARWARD component which pushes the lower body rearward (and down) and effectively tilts the top of the rotor shaft forward (by pushing the lower end of axis rearward). This helps tilt the rotor disc forward, at least countering the vertical back-pushing (disc rotating) drag on the tail boom, and helps forward flight when coupled with the effect of noseweight.

4. Left turns involve the rotor blades on the right side having reduced airspeed as the heli moves forward, compared to straight forward flight (more "tailwind" for the rear-moving blades on the right side), and those on the left side have a slightly smaller change as they are closer to the inside of the turn. This means that the blades on the right side slightly lose lift compared to those on the left. Precession converts this (90 degrees in the direction of rotation) so that the front half of the rotor disc is raised and the back half of the disc is lowered, tilting the rotor disc rearward. Thus the main disc lift vector is tilted rearward, and the heli slows down in left turns. The exact opposite thing happens in right turns.

FORWARD FLIGHT ON RIGHT TURNS:

When the tail rotor pushes harder (left) to rotate the body clockwise for a right turn, it also applies a force under the center of lift that tries to tilt the main rotor axis to the right (pushing the bottom of the axis left). The gyroscopic "resistance" of the upper rotor pushes down on the rear of the lower blade on the left side and pulls up on the rear of the lower blade on the right side. This gives more lift to the main lifting lower rotor disc on the left side and slightly to the rear since the lower blade is lagged .... and THAT pushes the heli forward and to the right!

Clint wrote:OK.

I've been tooling around with it and figured out how to trim the heli
bending different parts, adding weight, peice of tape here and there etc.

It's flying very slow forward at all times. hardly any trim on the tx, only slight adjustments as battery fades.

lastly i'm going to remove the throttle return spring.

here's a pic of how to trim this little beast. I'll get a real pic when my
camera batteries finish charging.

steelwoolghandi wrote:http://www.radioshack.com/product/index ... 62.2032402

Bilbo I posted this link earlier in the thread here is where I ordered mine I had to get mine on line as the stores here were not going to get them in for some time.

Clint wrote:Do you guys have to charge with the tx on or off?

Mine will only charge with the TX on.

TX batteries get pretty warm. thinking about adapting a 9v wall unit for
charging. 1.5v x 6, as i dont think i have a 7.2v wall unit (1.2v x 6).


Tip: Also dont charge the heli all the way. the first 30-40 seconds of flight on a full lipo is scary(wasted charging time).

I find that a 15 minute charge is a good balance
and gets the lipo in it's sweet spot voltage wise.
(even 5 minute use, 5 minute charge works well. lipo doesnt care.)


also the propo is sweet on this thing. both channels are propo(unlike the aero ace). if you end up decimating the heli, toss the electronics in a bit.