WALKERA 4G6 REVIEW
By: Richard Wellington
Update: See Section Titled "UPDATED BRUSHLESS UPGRADE AS OF 10-28-2009"
Update: See Section Titled "COMMING BRUSHLESS UPGRADE AS OF 11-15-2009"
In the course of a RC hobby addiction, my collection of Walkera and mini sized helicopters have always played a substantial role in my electric helicopters collection. However with the introduction of the Walkera 4G6 these micro and mini sized helicopters are fast becoming a major focus.
It was only over a year ago since I ventured into the world of micros and minis when miniaturization of helicopters is at its infancy. Back then, the 4#3/4#3A/4#3B was the first hobby quality helicopter targeted for the indoor or backyard market. Then, in quick succession, it was the Gaui 100/200, the 4G3, the Kyosho Caliber 120, the Quark, the CB180 and now the Walkera 4G6.
There were plenty of failures and successes in the group. One of the key and original competitors is Walkera, a prolific developer and manufacturer based out of Guangzhou, China. Although their line covered a whole range of flying contraptions, the micro helicopter line was the standout that seized the market more than two years ago. The lineup leading up to the 4G6 included the Lama 2-1, the 4#3B, the 4#3Q and the 4G3.
Fluent in both Mandarin and English, I've a distinct advantage when it comes to communicating and making friends with both vendors and developers, especially those located in China. Although there are numerous insider sources, there will be no disclosures here for obvious reasons.
SPECIFICATIONS
With a length of 270mm, a rotor diameter of 302mm and weighing in at 92.5g, the Walkera 4G6 is just slightly larger than the 4G3. All main rotor mechanism has remained unchanged from 4G3 architecture. The enlarged canopy provides extra space for an ever increasing number of electronic components.
The 4in1 combine the receiver, the gyro, the mixer and the signal converter. Some consensus continue to vote for separating these components which allow pilot to make customized upgrades. In my opinion, if Walkera were to split up these components, the additional weight will be the downfall. The ESC is marked as Wk-WST-10AL which I assume uses brushless signals from the 4in1.
By far, the most significant and break through on the 4G6 is the direct shaft-drive tail. It's a highly optimized piece of mechanism that is deceivingly simple and functionally rivals much larger scaled helicopters in performance, reliability and durability.
DEVEOPEMENT
As an avid helicopter enthusiast, a self-proclaimed inventor and a Walkera insider, I have had my share of pulling apart helicopters, making modest and substantial modifications. But I will say that there is definitely a discord between expectations and results. Only with experience, extensive flight tests and continued tweaking using in house manufacturing capability can a developer like Walkera optimize an intricate and complex piece of gadgetry such as the 4G6 within a window of opportunity per say.
Walkera's first collective pitched micro is the 4G3 release on the fourth quarter of 2008. This predecessor has since morphed into a stunning 3D performer, the juiced up 4G3 turbo double brushless. The big success of the 4G3 provided the necessary impetus for Walkera to pursue a direct drive tail for the 4G6.
The first attempt is a direct belt-drive tail which failed miserably. The skinny belt inherently lacked sufficient tension to consistently mesh with either gear. Miniturized notches that wore out quickly didn't help either. That leaves the only other direct drive option available - a shaft-driven tail.
THE SHAFT DRIVE TAIL
Let's just say there is pro and con to every design choice. At first glance, the advantage of the direct shaft drive mechanism is apparent. Like an axle of a car, the shaft draws its power directly from the main motor eliminating the need for a separate tail motor. A tail motor, if not properly paired with a fast ESC, produces a delay that affects the effectiveness of the gyro and the control responsiveness for proper tail orientation and stability. Further more, a pitch controlled tail offers immediate acceleration and deceleration whereas a tail motor takes time to accelerate and decelerate. In regards to weight, the tail motor is offset by additional mechanisms required to control the pitched tail rotor so there is no obvious advantage for either design.
When compared with a direct belt-drive system, the shaft-drive system offers a more streamlined look. The shaft drive seems especially durable with the shaft contained and protected by the tail boom. However, any crashes, vibration or flex causes the shaft to rub against the inside of the boom. The resulting friction produces heat and eventually wares out the boom and the shaft while draining power and torque. Early tests showed that vibrations might cause continued friction and heat that will eventually damage both components. To overcome possible damage, Walkera has added supporting trusses to limit vibration and to better sustain minor crashes.
Walkera has really done an outstanding job on the shaft tail mechanism by using the lightest possible design. At this point, I don't see a need for a bearing to ease the friction between the boom and the shaft. If need, a bearing will certainly increase the diameter and thereby the weight and the complexity of the boom.
MAJOR IMPROVEMENTS
Since stability and ease of flight has been of major concern on micro and mini helicopters, Walkera has invested extra effort to improve its gyro technology. In comparison to the Gauis and the Calibers which are supposedly larger and more stable aircraft, the Walkera 4G6 new and improve HH gyro easily out performed either competitor. That came as no surprise since just last month I had the opportunity to make a similar comparison that baffled me. The Walkera 5#10 was a winner over the Esky Lama 4 and both overshadowed the much more costly E-Flite CX2. If not for the E-Flite's existing marketing network, the CX2 would have been eliminated months ago. Oh well, this is not the first time that I see a big disconnect between quality, price and market share.
FLIGHT TEST
With 4G6 parts still on the horizon, my cautious initial flight tests provided a preview of what's to come. As with most Walkera helicopters, the blades were not perfectly balanced. Otherwise the helicopter flies right out of the box. There is plenty of punch from the stock brushless motor that exhibited more power than what I had expected from a 4G3 brushless motor. In mild outdoor conditions, the 4G6 is extremely stable for a micro sized helicopter. The tail hold is solid but only after some tuning and adjustments. As far as 3D performance, it's a very versatile beast despite being heavier than it's close cousin, the 4G3.
After a couple of days of getting use to the 4G6, performing typical loops, back loops, tic-tocks, hurricane and other tricks have gotten a bit more comfortable. But risks remain, I've already replaced the blades several times, the feathering shaft twice plus other minor parts.
INITIAL MODIFICATION & UPGRADE CONSIDERATION
Let's look at some possible upgrades to consider. Since I've had substantial improvement on my 4G3 motor upgrades, this is logical place to start. My first instinct is to try different motors first because that's the easiest item to change out. Well, after trying 4 different motors there were some surprises. Although the new 4G6 brushless motor may looks like the 4G3 brushless motor, the new brushless motor outputs 35% more power. This fact alone eliminated a lot of possible upgraded motors currently available on the market. Now I'm thinking, "Walkera had better not use the same stock number on both because they look like the same motor on the exterior."
The only hope that I'm holding out for is the coming Turbo Ace motors for the 4G6. The Turbo Ace 91416 paired with a 16T pinion turned out to be the ultimate combination for the 4G3 and there are plans to duplicate that effort for the 4G6. Since the 4G6 is a slightly larger craft compared to the 4G3, many of us suggest the possibility of going to a 2-cell setup to increase voltage, power and flight duration. That will involve the pairing of a comparable ESC and battery with a larger motor. Shall we keep our fingers crossed on this possibility?
The other upgrade opportunity is to increase rotation through larger pinions. In this attempt, the 20T intermittently cogged on startups and the 18T produced higher temperatures on the motor. At this juncture neither option is worth taking a risk on.
UPDATED BRUSHLESS UPGRADE AS OF 10-28-09
The long awaited Turbo Ace brushless upgrade to boost stocked 4G6 lift and torque didn't take that long after all. The surprise was that it turned out to be the Turbo Ace 81220 based on an updated outrunner (not an inrunner like the previous 91416 brushless upgrade for the 4G3) brushless 8g HP08-2 with a custom 20T pinion. Only a week ago, the initial HP08 or HP08-1 did not have the correct combination of kv speed to optimize startup and performance. Now, with the 81220, Turbo Ace has implemented a screening process to separate new HP08-2 motors for integration on both the 4G6 (81220-4G6) and the 4G3 (81220-4G3). A couple of precautions here: First, the Turbo Ace 81220 is an outrunner motor and wires have to routed away from the spinning canister to avoid damage and second, the 81220 has to be soldered directly to the ESC other wise the motor will not achieve full power and won't start properly. The custom 20T pinion come installed at specific depth for either model. And for RTF helicopter packages, some of the new 4G6 and 4G6 RTF helicopter packages now include this 81220 upgrade which is some time referred to as the Turbo or the Hot Rod helicopters. Almost over night, I'm looking at new videos and forum postings on this recent break through.
BRUSHLESS UPGRADE AS OF 12-15-09
If you are still looking for a save yet powerful brushless 4G6 options, the new Turbo Ace 31714 inurned is what should have been included in the stock 4G6. Where as a 3D pilot favors the 81220, the average 4G6 pilot will benefit from the swift and instantaneous power from the 31714. There is no equal to the pure exhilaration from this wonderful little speedster. However if you have an insatiable appetite for intense velocity that cut through the wind like an arrow, the 2-cell 80814 is the new paradigm of outdoor micros. For me, the 2-cell integration is a natural progression as we upgrade to more powerful motors. To make this a "turn key" option, Wow will so offer the 2-cell battery (7.4V) so I get everything in one click.
In summary, all three Turbo Ace options are equally valid 4G6 upgrades depending on your priority - the 81220 for extreme 3D flight, the 2-cell 80814 for power and acceleration and finally, the 31714, a beautiful blend of power and maneuverability. For me it's not a matter of picking one over the other but which one first.
TURBO DOUBLE BRUSHLESS 4G3 VERSUS STOCKED 4G6
I thought it will be interesting if we were to compare the best and fully upgraded turbo double brushless 4G3 with the initial stocked 4G6. As the predecessor of the 4G6, you would think that the 4G3 has lost it's relevance in the market. A common myth is that the more complex and updated the helicopter the better performance and reliability. For me, preference for specific performance comes in different flavors.
TIME TO SELVE SOME OF MY OTHER HELICOPTERS
One of my favorite backyard helicopters is the Gaui 200. It's a wonderful mini sized helicopter that's both powerful and agile enough to be fantastic 3D performer. However, the cost and maintenance of the Gaui and other mini sized helicopters are in the stratosphere compared to my Walkera 4G6. And for that reason alone I'm directing most of my financial resources to the 4G6. Even my Trex 450 may take a back seat for a while because of time and space constraints. After all, I can fly the 4G6 in virtually any park, yard or parking lot without the fear of damage and destruction.