Blade mCX

I have a model heli! My dad, with the help of brother Charles, got me a E-Flite Blade mCX for Christmas 2008. It is a coaxial rotor helicopter with a gyro, and DSM radio, so it is pretty forgiving. At the same time, you need to take care of flying issues.

I think the great thing about it is that it lets you take care of the control problems of takeoff, landing, flight, orientation, etc without having to concentrate on keeping the aircraft under control. To a certain extent it is somewhat like having a flight instructor with you keeping care of a bunch of other issues until you are advanced enough with those more basic issues. The flip-side of that very argument is that it doesn't let you develop some very basic control components, such as yaw control changes with power and collective pitch control changes, so it is totally backwards!

I guess the best thing about it is that it can get someone actually doing RC flying now, inside a house in the dead of winter, without much chance of destroying either the aircraft of the house!

E-Flite Blade mCX

Blade mCX Articles & Notes

Yikes -- The Heli is going wacko

When you are trimming out the heli, do so on a floor or other huge surface -- don't use a table-top or desk. Why? -- ground effect. A small enough surface can cause irregularities in ground effect which will have you trying again and again to trim it out. I've found that a smooth floor (no carpets) works great for this.

The other reason for learning and trimming from a smooth surface is to deal with the helicopter aerodynamics issue of dynamic roll-over. The heli rotor system is trying to make the heli go in some direction, but there isn't enough lift to fly yet. But the ground is grabbing the skids and keeping the heli in place. If the ground is smooth the heli would just slide across it, but since the heli is trapped it starts to tip over.

Watch out also for air currents when trimming; they can drive you nuts. Something as simple as the heating or air conditioning turning on/off, opening / closing some drapes, or opening or closing an interior door can change these small air currents around on you and cause oddities.

If you max out the radio trims, and the aircraft still moves around... It may be time to adjust the pushrod links to get the control throws back to the range where you can trim it out by hand. That will probably happen after a big-enough accident (or enough) that the jar of landing (crashing) shifts a pushrod in a ball-link. BUT before you do that, try playing a bit more; due to the construction of the swash plate there is a slight bit of coupling between the pitch and roll servos. This interaction can be a bit frustrating to zero out, but it is easier than popping the canopy and adjusting the push-rod lengths.

If suddenly your heli no longer seems in trim and wants to drift all over the place ... there may be a quite simple explanation: the battery shifted aft and altered the CG of the helicopter. Now the heli will want to fly backwards instead of hover at neutral stick. OK. Just land, push the battery back into place, and continue flying!

It tripped on itself ????

I was having a wonderful flight with some great long distance manuevering the length of the house. The heli was headed back towards me with full forward cyclic deflection doing great. It crashed spectacularly in midair. It was like it hit a wall. Its forward motion stopped near instantaneously. But worse, it spun around in the air in three dimensions like it was tangled up in something. The words I still use to describe it are: it was like it tripped on itself. Well, it turns out that description may not be so far from what occurred:

  1. There is a real possibility that some sort of rotor-strike occurred, possibly a rotor/boom strike. But more spectacularly, if a rotor/rotor strike occurred, that could really account for the airborne antics of the heli as it crashed.
  2. It may have been a result of coaxial helicopter stability, which then turned into something else (such as a strike) once the airframe was upset. See the following section on coax heli aerodynamics to help understand what may have really happened.

Coaxial Rotor Helicopter Aerodynamics

A work in progress while I goto work myself!

Many of this issues are actually generic helicopter issues; I've just put in some of the things which explain why this heli flies like it does, so people can get a grasp on what is happening, and go look at a real helicopter aerodynamics or flight book, such as the FAAs.

Common Repairs & Upgrades

The good folks (Warren and Dave) at Pope's Hobbyland in Wausau, WI gave me a few good tips about the helicopter:

After mentioning broken parts, that being said, The helicopter is darn near unbreakable; the worst that I've seen is the trim keeps on changing radically. I think that is because the either the swash plate is moved around slightly on the rotor shaft, or because the push-rod ball ends are being ratcheted across the threads by impact.

Even the spectacular midair crash that I wish I had video of resulted in no real damage ... except perhaps to strip the extreme aft travel from the linear pitch servo's worm gear. It may not even be real damage from that incident -- I need to check another mCX to see if it does something similar.

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Last Updated: Fri Jan 30 22:56:24 CST 2009
Bolo (Josef Burger) <>