Lama v4
The E-Sky Lama V4 is a small, 4-channel, remote controlled electric coaxial helicopter produced by E-Sky. It is the fourth model in the Lama series of coaxial remote control helicopter, aimed specifically at beginners in the world of r/c helicopters.
Like other similar co-axial models, the Lama V3, V4 And Co-commanche are mass manufactured in China and are sold ready-to-fly (RTF) out of the box, requiring the pilot to only charge and install the standard 7.4 V 800 mAh 2-cell Li-poly battery.
Model revisions
Succeeding the previous Lama V3 and Lama V2 models, and preceding the Esky Co-Commanche, the Lama V4 is mechanically and electrically similar to the Lama V3, except for the canopy and tail design. The Lama V3 and Lama V4 servo linkage arms are also designed differently. The Esky Co-commanche, sometimes advertised as the Esky Lama V5, is effectively a Lama V4 with a later canopy design. The tail rotor on the Co-commanche is for aesthetics only and serves no function over flight.
The design
Like in other similar coaxial remote control helicopters, the aircraft's power is generated from a dual DC motor system, pinion and co-axial counter-rotating blades. The "4 in 1" unit is a dedicated electronic control unit combining the functions of a receiver, mixer, gyroscope and electronic speed control. This control unit regulates both motors' speed to provide altitude control (climbing and descending), as well as the relative motor speed to provide automatic heading hold and yaw control. The transmitter and receiver modules use FM modulation for the radio signal carrier and Pulse Position Modulation (PPM) for the control signal.
The helicopter uses a simplified coaxial rotor system, with two pairs of rigid fixed-pitch coaxial counter-rotating rotors, of which only the lower one is fully controllable by a swashplate, while the upper one is only stabilized by an inertial fly bar. The swashplate movements are controlled by a pair of micro servos, which allows for omnidirectional flight control.
This particular simplified coaxial rotor arrangement is shared by virtually all small scale electric helicopters on the market, and has the advantage of being mechanically simpler compared to the collective pitch coaxial arrangement with two swashplates, usually found in most real coaxial helicopters.
This choice however poses some limitations on the aerobatic ability of any helicopter using this design, in particular regarding its maximum speed and its ability to negotiate wind and to perform rapid air maneuvers without becoming unstable.
The LV4 plastic canopy, which is available in either blue or silver, can be easily disassembled and reassembled with no, or minimal use of tools, allowing easy access for tweaks, adjustments and running repairs to the aircraft. The Lama V4 uses many of the same parts of its predecessor, however, uses a redesigned and uprated frame kit and canopy. Custom canopies are also available for the E-Sky Lama V4, ranging in designs from police insignia and colors, military style and rescue helicopters. Many r/c pilots have used canopies from other co-axial helicopters of similar design, including the E-Flight Blade CX. The later-designed Esky Co-commanche canopy is also compatible with the Lama V4 with mild modification(s).
Coaxial radio control helicopter such as the Lama V4 are renowned amongst remote control helicopter enthusiasts, especially beginners, as being relatively stable and easier to control compared to single-rotor helicopters, making them ideal for beginner radio control helicopter pilots.
Specifications
- Main rotor diameter: 340 mm
- Body weight: 230 g
- Length: 360 mm, width: 85 mm, height: 175 mm;
- Power system: 2 x 180-series motor
- Transmitter: 4 channel FM PPM
- Mix controller: 4-in-1 controller (contains receiver, gyro, mixer, and speed control)
- Servo: 8 g, 1.3 kg·cm, 0.12 sec/60°
- Battery: 7.4 V 800 mA·h Li-polymer battery
General points of discussion
The general experience has been that the E-Sky Lama V4 Helicopter is only capable of flying indoors or outdoors on a completely calm day with no, or very little, cross wind. Modification (see below) can be made to the Lama V4 and similar helicopters to assist the r/c pilot flying outdoors with limited effect. As stock, like other dual rotor co-axial model aircraft, the E-Sky Lama V4 pilot is advised not to fly in such conditions as cross winds.
The upper set of rotor blades (A) are stabilized by a weighted fly bar which counters tilting movements. The lower set of rotor blades (B) are designed to steer the helicopter by tilting a "swashplate" which in turn tilts the entire rotor by changing the pitch in a complicated process called "cyclic".
If the lower rotor tilts too far, it causes the upper blade (which is not connected to the swashplate) to try and counter the tilt. Basically both rotors are tilted towards each other, and if they intersect, resulting in a "blade strike" or "blade clash", causing the aircraft to instantly descend out of the air. In non-static air (wind and/or turbulence) it takes larger steering movements to stay in a stationary hover which can overwhelm the co-axial design.
Also, exceeding a certain angle of roll or pitch even without a blade strike will cause the helicopter to go out of control and crash, as the top stabilized blades' weight and angular momentum will tend to render the helicopter unstable and insensitive to corrective control input. This can be caused by too aggressive maneuvering or just a sudden gust of wind, either resulting in an excessive roll or pitch angle. This flight condition is usually referred to as "death roll" by enthusiasts.
Modifications and design upgrades
Replacements for standard plastic parts
There are many modification available for both the Lama V3 and the Lama V4, which replace certain plastic mechanical parts such blade grips, the swash plate, servo linkages and rotor heads with aluminum parts, allegedly offering increased durability and mechanical strength, although not necessarily improved flight characteristics. Other parts that can be replaced include the landing skids and battery holder assembly as well as the motors, which can be replaced with more powerful motors of the same form factor.
One particular modification provides an extended (longer) upper rotor head, which increases the distance between the upper and lower rotors and allows for faster turns and roll/pitch changes without causing a blade strike.
Upgrades for the standard rotor blades
Owners may upgrade the standard blade rotors (made of flexible black plastic) with more durable blades usually referred to as "Xtreme blades", made from thicker white PP. These blades are thicker than the standard ones, stronger, and can withstand more severe strikes and collisions than the standard ones, without developing cracks or breaking. Their airfoil shape is also claimed to generate more lift than the standard ones, however they also have an increased weight and angular momentum, which reduces agility and control response somewhat.
Other upgrades
Lithium Polymer (Lipo or Li-po) batteries have advanced significantly in recent years, allowing small high output versions to be produced at low cost. The stock Lama v4 is supplied by E-Sky with a 7.4v 800mah battery. R/c pilots have experimented and found that the E-Sky Lama V4 is capable of flying with more powerful batteries ranging from 7.4v 900-1600 mah units. The advantages are throttle power gains and prolonged flying times.
See also
- E-flite Blade CX
External links
de:E Sky Lama V4