A micro dynamo capable of inverted flight, flips and more!
A few years ago when micro electric helicopters such as the Blade mCX, PiccoZ and many others were introduced, we were all impressed that such tiny machines weighing under two ounces could actually fly well indoors. Then we had a dream: when might we one day fly 3D aerobatics indoors with micro electric helicopters? That day has arrived sooner than I expected. The Blade mCP X is not touted as a full 3D helicopter, but at least it is capable of doing flips, funnels and inverted flight in a confined space. The Blade mCP X is quite an engineering marvel, and the price at just over $200 with a 2.4 GHz transmitter is reasonable, too, because the little mCP X includes a full 3-axis gyro stabilization system. The price of this little beauty is even more affordable when buying just the helicopter (bind & fly or BNF version), which is the version I have because I use my own DX7 transmitter.
First, let me explain why the mCP X is such an impressive engineering achievement. Aeronautical and control engineers who are familiar with the design of moving mechanical systems are familiar with the dichotomy between stability and controllability. These two aspects usually have contradicting design requirements. If one wants to make an RC model helicopter very stable, then it always means sacrificing control response and control speed. If we want a model helicopter to be highly aerobatic, then it cannot be as stable as a rock. This is why we have docile model airplanes and helicopters designed specifically for beginners, and others that are highly aerobatic and designed for experts with very well trained thumbs.
As I have explained in my review of the T-Rex 100 in this issue, there is a parameter called time constant. Time constant is a measure of how fast a system reacts to inputs or perturbations. In general, the smaller an object, the shorter the time constant. The challenge of making any micro electric helicopter fly well in a confined space is to make the model very stable, and in effect slow down the time constant so that the pilot has a chance to react and control the model. I am almost reminded of a science fiction movie in which time is altered and the super heroes can see things move in slow motion, and hence they can dodge bullets.
The best mechanical way to make a micro helicopter more stable is to add a heavy flybar, and remove the control paddles. This is what the designers of the mCX, and PiccoZ, and many micro coaxial helicopters have done. However, the drawback is these micro models become very tamed and they do not possess fast cyclic control response. A flybar acts like an inertial reference, or a mechanical gyroscope, which will always try to maintain its attitude in space. If the helicopter fuselage is perturbed by a gust of wind, then the helicopter fuselage and main rotor shaft will form an error angle with the spinning disk formed by the A stabilizer bar. Since the main rotor blade pitch control is connected to the flybar, the error angle will automatically put in a correction to the rotor blades to help restore the helicopter fuselage back to level again. If we simply eliminate the heavy flybar on these traditional micro electric helicopters, they become very squirrelly and not flyable anymore. If we remove the mechanical flybar on a model helicopter, then we need an electronic substitute.
The secret to the mCP Xs success in being both very stable and very responsive lies in using electronic stabilization along with a flybarless rotor. Horizon engineers added an electronic 3-axis gyro stability augmentation system (SAS) that uses three MEMS rate gyros, and they also added PID feedback. During hover, the Blade mCP X is quite stable owing to its SAS, and when you do not disturb it, it will just sit there hovering in space.
However, when you feed in a cyclic command, you are feeding in a feed forward command to bypass the triple axis gyro SAS system and the little helicopter becomes a little flybarless helicopterand is super responsive. Although the SAS helps make the mCP X very stable, it is not a helicopter for beginners. Once the helicopter starts moving, or when you put in a cyclic command, it responds very quickly. In the hands of a beginner, the mCP X can quickly go out of control and crash. However, in the hands of experienced pilot, the mCP X is fantastic. It sits there when asked to, and when a command is prescribed, it responds instantly. That is why it is possible to roll the mCP X or do forward or backward flips, or loops, or fly inverted indoors. Realistically, a room with a 10 to 12 foot ceiling and 20 ft by 20 ft is need for doing some 3D. An indoor basket ball court would be even better.
TIPS FOR SUCCESS
Add extra Expo in the first few flights to get used to the control feel. Be on the ball, once the model starts to move it requires fast fingers on the control stick.
The mCP Xis for experienced pilots and is like a little dynamo on steroids and is ready to leap into the air for action. The mCP X embeds the receiver, 3-axis gyro, and three eCCPM servos all on one printed circuit board. This design is used successfully by Horizon Hobby for many of their E-flite products, such as their mCX2, Tandem CH-47 and even their micro series RC foam airplanes.
The mCP X uses a single cell 200 mAh LiPo battery. A full charge provides 3 to 4 minutes of hard flying and 6 minutes of hovering. Amazingly, the mCP X has quite excellent vertical performance. At about two ounces of weight ready to fly, there is no shortage of acceleration. The model is quite zippy. There is plenty of power to do a hovering roll. It is harder to do 3D with this tiny model as compared to a 50 size helicopter because small models are harder to see and they are quite sensitive to control inputs. Make sure you put in exponential. The control values described in the instruction manual are spot on. However, I added 10% more Expo. The mCP X is like a scaled down RC helicopter. It has a true swashplate with a 120 degree eCCPM (electronic cyclic-collective pitch mixing) control system.
This little heli is soo much fun, you cannot put it down! It has a surprisingly good power to weight ratio. I looped it in an indoor basket ball court. Inverted hover is very stable given its 3-axis gyro.
By Tony Yap
The New England winter is in full force, and the snowfall here in Connecticut has to be measured in yards rather than inches. Not being able to even get to a suitable flying field has left me with some itchy fingers! When I first heard of E-flites Blade mCP X, I knew I had to have one!
Already owning the coaxial Blade MCX and the single rotor, fixed pitch Blade MSR, I knew it was only a matter of time before the guys at E-Flite came out with a collective pitch helicopter. However, I was totally blown away when I heard that it was flybarless! Having full 3 axis stabilization in such a small package is impressive, and now, the full, 3D flight is capable indoors inside a moderate sized room!
I received the ready to fly version of the Blade mCP X. It comes with a genuine Spektrum DX4e radio, which includes dual rates, a thottle hold switch, and stunt mode. The Spektrum DX4e is a full size transmitter with normal size gimbals, most pilots will feel right at home holding the DX4e. Out of the box, it comes already pre-bound to the helicopter and 4 AA batteries for it are included. Compared to its cousins of the past, the mCP X uses a larger 200mAh, 25C battery for power. Included in the kit are two batteries, and a variable rate charger that is powered by a standard wall outlet.
The helicopter itself is tiny and almost weightless at 1.6 ounces. Sporting a rotor head diameter of about 9 inches, the mCP X is a wonder of micro engineering. The main control board provides multiple functions: DSM receiver, two speed controls for the main and tail rotor motors, three servo drivers, and the 3-axis flybarless system. Three ball bearing supported linear servos actuate the swashplate, and the main and tail rotor motors are both coreless for high torque and long life. The mainshaft of the mCP X is carbon fiber for light weight and so that it wont bend or break during minor mishaps.
Included in the box are two sets of main rotor blades, one set geared toward high maneuverability and the other set with a weighted leading edge that is intended for smooth and fast forward flight. Also included is a spare tail rotor, some canopy grommets, and spare rotor head linkages.
Charging the batteries with the included charger at 700mAh as recommended by the manual takes about 15 minutes. The battery slides into a cradle under the landing gear and is held in with a friction fit. With the transmitter powered up, plug in the flight battery and quickly set it down to allow the flybarless system to initialize. Once that occurs, a blue light will illuminate from under the canopy to indicate everything is ready to go.
Pushing the collective stick forward brought the mCP X up into a hover. For a helicopter as tiny as it is, it was quite stable, and cyclic response was crisp. If you happen to be in a small room, it does get buffeted a bit by its own downwash, but once you rise a foot or so above the surface and get out of ground effect, things seem to smooth out a bit.
Out of a hover I pushed the right stick forward. The mCP X will outrun pretty much anything else that is capable of flying indoors. It is QUICK! While indoors, its best not to let the speed get too high until you get used to the responsiveness, as the walls start approaching fast. I did manage to snag a few obstacles in my basement at a pretty good rate, and only damaged the tiny pitch links in the rotor head. Fortunately, Horizon and E-flite include four spares in the box, and I was able to get back into the air within seconds.
The tail rotor holds amazingly well, and I was able to perform pirouetting circuits in my basement! Similarly, backwards flight is no problem, with the tail holding solid throughout the manuevers.
Of course, with a collective pitch machine, I was eager to see how well it would do inverted. I toggled the stunt mode switch and gave it a go. At first, I did this outdoors when it was calm, just to get a feel for the responsiveness and to give my self a little extra room just in case I needed it. The MCP X handles just like its larger cousins, and hovered well inverted with only minor corrections to keep it stable. Funnels, flips, and inverted backwards flight are within the mCP Xs flight capabilities if you are! There is plenty of power for smooth 3D flight.
I gotta say Im totally in love with the little mCP X. The dream of being able to do 3D heli stunts in the confines of my own house has finally been realized! Its small enough to fly indoors, yet manueverable enough to challenge even the seasoned RC heli pilot. Its also light and tough enough to handle most mishaps unscathed, so do 3D until your hearts content! Horizon really has a winner with the Blade mCP X!
HELICOPTER: Blade mCP X
DISTRIBUTOR: Horizon Hobby
TYPE: flybarless micro indoor electric helicopter
FOR: Intermediate to advanced
FLYING WEIGHT: 1.6 oz. (45.5 grams) with battery
LENGTH: 9.25 in. (235mm)
MAIN ROTOR SPAN: 9.65 in (245mm)
TAIL ROTOR SPAN: 1.40 in (36.5mm)
RADIO: electronic board consisting of receiver, ESC, 3-axis stabilization system, three micro servos
MOTOR: micro electric brush motor
ONBOARD BATTERY: single cell 3.7V 200mAh LiPo
DURATION: 3 to 6 minutes
COMPONENTS NEEDED TO COMPLETE: Either buy the version with a transmitter, or provide your own Spektrum DSM2 transmitter
PRICE: $219.99 (Blade mCP X RTF); $179.99 (Blade mCP X BNF)
SUMMARY: In the hands of an experienced pilot, the mCP X can roll and flip indoors. It features very innovative engineering for a micro heli.
The mCP X gets two thumbs up for innovativeness. It opens the door to a whole new style of RC indoor flying. I am sure in the next few years, we will see many manufacturers make micro 3D RC helicopters for indoor flying. This will bring rapid advancement in micro electric helicopter technology. The mCP X is just the beginning of a very exciting new era. I am sure E-flite will one day produce an mCP X version 2 and it will be even more stable and more aerobatic. For now, I am very impressed and love my little mCP X.
Blade Helicopters, dist. by Horizon Hobby, www.bladehelis.com , (800) 338-4639
E-flite, dist. exclusively by Horizon Hobby Distributors, www.e-fliterc.com , (800) 338-4639