For more than ten years, I have always been an admirer of German engineered Vario scale helicopters. Vario helicopters have different engineering features when compared to other German, Asian, and American designed model helicopters. Vario designers experiment with something radical on every new model that they create, and each model demonstrates a different outside-the-box thinking. For example, the Vario Viper has its swashplate located below the rotor shaft bearing block, and has a 540cc tank behind the main shaft and a second 400cc tank in front of the main shaft. Regardless of whether people like it or not, there is no other R/C helicopter in the world like the Viper. The Vario Extreme uses an aluminum bulkhead instead of flat plate sideframes, and it uses a toothed belt transmission to reduce helicopter noise, and offers a choice of either clockwise or counter-clockwise rotation main rotor. The Skyfox Series is a refinement on the classic Heim mechanics, but with 120-degree electronic CCPM (Cyclic-Collective Pitch Mixing) control and a three-bladed cooling fan underneath the engine to draw air around the engine for cooling. The Benzin Trainer is the most popular gasoline engine powered helicopter in Europe and more have probably been sold than any other gas helicopter in the world. The new Benzin Acrobat, introduced in 2003, is formulated for 3-D enthusiasts. The Boxer is a big aerobatic helicopter, powered by a twin-cylinder OS 160 four-stroke engine, and employs two exhaust pipes to create a quiet and unique sound in flight. The Boxer and Xtreme were popular in the German Poting Cup 3-D contest because bonus points were awarded for quietness. The Silence is a big electric helicopter powered by 30-cells and a Kontronik brushless motor.

In the last issue of Rotory, we provided a review on the construction of the Observer, an industrial camera platform offered by Bergen R/C Helicopters. In this issue, we'll continue the review to include a closer look at the control system, the camera mount, and a few options for videotape or still photography.
Regardless of how sophisticated a camera platform is ­ its end product, "the shot," is only as good as the ability of the pilot and the platform. The control system plays an important part in controllability - to get the machine to the shot, as well as the ability to "park" the machine in a stationary position if needed.
The Bergen Observer uses a "standard" elevator type "single servo" swashplate control, instead of CCPM. The control system is similar to those found on popular models such as the Raptor 30-90 machines. The roll and pitch control does not interact with the collective movement, which makes the control system on the Bergen work amazingly well. In fact, Bergen machines used this control system before the first Raptor model was ever released. Was it a coincidence that Raptor designer, Taya, came up with the same control system? I guess we'll never know . . .

In 2003, Airtronics introduced a new radio called the RD8000, which is a more powerful eight-channel version of their popular six-channel RD6000 Super. The RD8000 system, with receiver and servos, is available as a helicopter or an airplane system. The only differences between the airplane and the helicopter systems are the servos and the receiver NiCd battery size. The helicopter system comes with five ball bearing supported 94731Z or 94322Z servos that are suitable for heli use, and an 1100 mAh receiver NiCd battery. The heli system with five 94322Z servos is priced less than the heli system with five 94731Z servos. The 94322Z servo is for 30 to 50-size helicopters. The 94322Z has 50 in-oz of torque and a travel speed of 0.20 second per 60 degrees at 4.8 volts. The higher torque, double ball bearing 94731Z servo utilizes a coreless motor and offers performance comparable to Futaba 9202 and JR 4131 servos, but the 94731Z has an excellent gear mesh. All Airtronics servos now come with a blue color Z-style connector that is 100% compatible with JR, Futaba, and Hitec receivers and servos.
For extreme 3-D fliers, Airtronics offers an optional series of super high-speed and high-torque digital and analog servos, powered by coreless motors. The super analog servos include the 94357Z, 94358Z, 94359Z, and 94360Z. The digital servos include the 94751Z, 94755Z, and 94757Z and 94758Z. The difference between their high performance series analog and digital servos is the analog servos have more static torque, and the digital version has more holding torque . . .

Everyone agrees that lighter aircraft fly better than heavier ones with the same power plant. This is very important with electric helis, "E-Helis". To remove some weight that will not make the heli any less durable, I did the following. First off, I removed more of the stock canopy area by adding extra holes to save weight; which in turn delivers more performance and little increases in flight duration, since the heli isn't dragging around extra ballast weight. Within the past year, I have come up with an aftermarket clear paintable canopy for the VoyagerE that resembles the JR Vigor silhouette. It fits right onto the stock canopy mounts of the heli and fits both stock framed and carbon framed VoyagerE helis. We have found that even with multiple colors and decal schemes that it weighs less than the stock canopy trimmed out for weight. In addition, I personally feel it looks 100% better as well.
To save more weight, you can also remove some of the stock frame material where the receiver and the gyro mount. I also highly recommend the selection of lighter radio equipment too, for use in the VoyagerE. Even though you can use standard size servos; using mini servos can save almost 2.5 ounces in the flying weight

At first site, the visuals of the new Thunder Tiger Raptor 90 is not a retina detaching experience. Appearance-wise, it looks like that of the standard Raptor 60 machine, however, that's where it stops. On the inside, the Raptor 90 production kit is a re-engineered platform, capable of supporting the larger .90 class engine. On the design end of things, the R-90 uses many of the traits of the past R-60 V2, except it's now beefy, improved, and a bit larger.

The Raptor 90 kit is not for the weak and timid. With its "big block" 90-engine, the kit falls into the category of a rocket ship with rotor blades. For those who have not flown a 90-helicopter before, the best way I can describe it is you can do whatever you like and never worry about much of anything. That is, except hitting the ground. Because of the R90's power-to-weight, you'll seldom do anything cyclic or collective-wise to "get into the engine."
As many manufacturers quickly learned, you can't just mount a 90-engine in a 60-frame and re-name it a 90. It takes a new frame design to properly mount the engine, combined with a gear train that can hold up to an amazing amount of power. While the Raptor 90 upgrade kits have been available for a while, they did not offer a lot of the needed improvements and options necessary to house the large displacement engine.

The rotor tach has been a standard on full-size helicopters since the early days due to the critical nature of maintaining exacting rpm (rotations per minute). The main reason is that structural limitations might be exceeded either by an excessively low or high rotor rpm (+/-15%). For the most part, models have the advantage of totally ignoring this parameter. There are issues we share with our bigger brethren, one of which is efficiency and another of cyclic response. A faster turning rotor will produce a more aggressive cyclic control and at the same time store more energy. The latter may be used to fly the machine through temporary situations, demanding a momentary spike in unavailable engine power. This is sometimes the case with the smaller models when pushed to the limits.
With any model helicopter rotor, there is a sweet rpm, which offers the best lifting averaged over all collective settings. However, this may not be ideal for a desired cyclic rate. It also may or may not be an optimum for a selected gear ratio needed to extract maximum engine power or efficiency, which of course would be the most prominent consideration. We may tweak the rotor and engine setup to meet the best compromise, but in the final analysis, we are often guessing.