VARIO Benzin - Rotory Modeler

VARIO BenzinGasoline Powered HelicopterJames Wang44ROTORY

This is a model for people who appreciate a big helicopter withimpressive German engineered parts. The entire kit ismanufactured in Germany by Vario, it features the proven Variomain rotor head, machine cut Delrin gears, long lastingcentrifugal clutch and clutchbell system, Vario metal tail rotorgearbox, stainless steel torque tube drive, and CCPM control.www.eastcoastvario.comROTORY45

Very easy to assemblekit with excellentGerman quality parts.TheBenzin Acrobatic is specially designed for the useof a 23cc Zenoah G230 engine. This gasolineengine, available from www.eastcoastvario.com,develops 3.5 horsepower and is capable of pullingthe 14.5-pound Benzin Acrobatic through loops, rolls and allFAI-like aerobatics. With a 6.72 to 1 gear ratio and thespecial Vario forward facing tuned exhaust system, themodel is very quiet in flight. The G230 engine possessesbrutal torque to spin 725 mm length blades at +11 to –11degrees at 1650 rpm in Idle-Up. This is a model for pilotswho appreciate a big helicopter with impressive Germanengineered parts. The entire kit is manufactured inGermany by Vario and features the proven Vario main rotorhead, machine cut Delrin gears, long lasting centrifugalclutch and clutch bell system, Vario metal tail rotorgearbox, stainless steel torque tube drive, and eCCPMcontrol. The Benzin Acrobatic is an even better gasolineengine powered helicopter than the Vario Benzin Trainerthat was introduced six years ago. If you are looking for aserious and rugged acrobatic gasoline engine helicopter,then this model should not be overlooked.I built a Vario Benzin Trainer five years ago. That modelflew very well, but was slightly underpowered because Iused an early version Zenoah 23 engine, and that modelweighed 7 kilos (15.5 pounds). In 2004, I started lookingfor another gasoline engine poweredmodel to replace the Benzin Trainerbecause I wanted an aerobatic gasser.After flipping through the 514 pageVario 2004 catalog, I decide - I had toorder their new Benzin Acrobaticversion. The Benzin Acrobaticfeatures new frames and biggerdiameter tail boom, but only weighs 14pounds. The Engine has been placedmore forward and the exhaust systempoints forward. Hence, the aircraft center of gravity willcome out exactly underneath the main rotor shaft with afull tank of fuel. I like the model very much, but the pricetag was $1650 for the kit, $296 for the engine, and $261for the special Vario muffler. These German Vario partsmated flawlessly. The metal swashplate has zero free play.Each mixing arm pivots on two ball bearings. The 45-degree bevel Delrin gears in the tail rotor gearbox runultra smooth and quiet. Each main rotor blade grip issupported on two radial bearings and one thrust bearing. Atoothed belt is used to transfer power from the clutch bellto the first stage gear. An Electronic CCPM controlsystem helps reduce the parts-count. This model is simple,functional, and elegant. Yes, it is worth getting.Mechanics Layout:The 23 cc engine is quite heavy; one G23 weighs as muchas two 90-size glow engines. Gasoline engines may not havethe power-to-weight ratio of high performance 2-strokehelicopter engines, but they have excellent fuel economyand come with a recoil starter. The G23 packs a goodpunch and tremendous torque at low rpm. Most 90-sizehelicopters use gear ratios between 7.75 and 8.45. Thelow revving G23 allows the Benzin Acrobatic to get awaywith a very low ratio of 6.72:1. The G23 engine sits on a 346ROTORY

Left: Close-up of thecarburetor and homemadeair filter system.Below: With gasolineengines, it is necessary toshield the spark plug wireto prevent radio noise.Joe has been flying Vario helicopters for 20-years himselfand he offers a building and painting service for Vario scalemodels. Joe is located in Massachusetts and can bereached at (508) 520-1867.The stainless steel tail rotor torque tube is supported bythree ball bearings. The torque tube needs to be cut tothe correct length by the builder. Read the instructionscarefully before cutting because the manual does not tellyou what length to cut the tube to, instead, it describes amathematical formula for you to figure out what length tocut the tube. The builder has to epoxy an aluminumuniversal joint terminal at each end of the torque tube.Then a rubber is sandwiched in the middle of the universaljoint to dampen any shock. It is a good design.The tail rotor servo is mounted directly on the tail boom.The tail boom has a 25 mm diameter o.d., which is the sameas the Raptor 90, Vario Xtreme, Vario Viper, and someother Vario helicopters. Twenty-five millimeters is a hugediameter, plus the Vario boom has a very thick wall. Thealuminum tail boom is sandwiched between two plasticclamps. The whole system is solid. The vertical fin is madefrom aluminum. No horizontal fin is provided.48ROTORY

Above: A toothed belt isused to couple the clutchbell to the main gear.Left: It is best to useVario No. 834/16muffler shown here.This $261 exhaust iscustom designed to fitthe Benzin Acrobatic.The Vario exhaustpoints forward toprevent tail heaviness.The center of gravityfor the finishedhelicopter comes outperfectly underneaththe main rotor shaft.

Control System:The instructions say, the Benzin Acrobatic isdesigned for 4-servo eCCPM operation, but extraholes are drilled and tapped in the swashplate topermit 3-servo eCCPM operation. I have used 4-servo eCCPM before and found that it could causebinding at extreme collective and cyclic settingsbecause the servo that is pulling, opposes the servothat is pushing. If 3-servo eCCPM is used, theservos cannot oppose each other. Modern digitalservos with metal gears are very strong, so it is notnecessary to use 4-servo CCPM. Make sure you useonly top-of-the-line servos, with at least 120 inch-ozof torque, and preferable metal gears. Futaba, JR,and Airtronics all make high torque servos with over120 in-oz of torque. If you want to try somethingnew, then consider the new titanium gear digitalservos from Hitec. Yes, the gears are made withtitanium! Hitec designed a high-speed version and ahigh torque version for RC robot and RC monstertruck use. They have almost 200 in-oz of torque andcome in standard size servo casings, which makethem fit perfectly in the servo cutout on the sideframes. You will find these specialty servos atwww.hitecrcd.com. The Hitec titanium gear equippedservos are perfect for a 14-pound helicopter like theBenzin Acrobatic and other huge scale helicopters.The main rotor on Vario helicopters spin in theopposite direction of most RC helicopters. Forexample, Raptor, Fury, and Freya all spin clockwise,the Vario models spin counter-clockwise. When aheading hold gyro is used, it does not make muchdifference which way the main rotor spins, theheading hold gyro will lock the heading equally well.The only noticeable difference is Vario helicopterslean to the left during hover, while other helicoptermodels lean to the right.The Bell-Hiller mixing arms on most Variohelicopters, including the Benzin Acrobatic, aremounted perpendicular to the blade grip. Many50ROTORY

Above: A 5 mmdiameter flybar isused. The rotor turnscounter-clockwise.Left: The control canbe set up as 3-servo or4-servo eCCPM(electronic cycliccollectivepitchmixing).The BenzinAcrobatic has ametal tail gearbox.

It is very important toget a fuel can and ahand crank fuel pumpthat are designed forgasoline, and not forglow fuel.Essential items for flying gasolinehelicopters: a red, one gallon carrierdesigned for gasoline and Coleman kerosene,Castor 927 2-cycle oil from Maxima RacingLubricant, and a special mixer bottle alsofrom Maxima.German helicopters use such a design. for example, theelectric Mikado Logo, Heim, Graupner, and some Robbemodels. The hollow plastic Hiller paddles only weigh 16grams each and provide quick cyclic control, but withreduced stability. I strongly recommend installing someflybar weights or use heavier paddles. This model has a5 mm diameter flybar, while all 60/90-size helicoptersutilize a 4 mm flybar. Hence, it is necessary to drill outthe standard 4 mm i.d. flybar weight and paddles to fitonto this model. A set of 50-gram Miniature Aircraftpaddles were later drilled out and fitted onto theBenzin Acrobatic and that made the model super stableand a joy to pilot; plus the large control surfacesprovided ample cyclic authority for aerobatics.The main rotor blades flap easily on the Benzin rotorhead. For vigorous aerobatic flying, one can add extrashim washers on the spindle to compress the rubber.Many 90-size helicopters use only a 10 mm diametermain rotor shaft, but the Benzin Aerobatic uses a 12mm diameter main rotor shaft, which is a good idea.Surprisingly, the Jesus bolt on the rotor head is only 3mm. I would feel better if it was a 4 mm bolt. I wassurprised, even the Vario turbine helicopter uses a 3mm Jesus bolt.Flying:The standard Benzin Acrobatic kit No. 8304 isdesigned for 725 mm length carbon blades. This is theversion I bought. There is also a long boom version,which is designed for 800 mm length carbon blades.The long boom version is used for carrying a payload,doing aerial photography, and smooth flying. Variorecommends the rotor speed be kept under 1400 rpm52ROTORY

when 800 mm blades are used. For performingaerobatics, it is better to get the standard BenzinAcrobatic kit and the 725 mm carbon blades. Thehelicopter kits include fiberglass tail rotor blades butnot main rotor blades. East Coast Vario(www.eastcoastvario.com) has 725 mm long, symmetricalairfoil, carbon blades designed specifically for thishelicopter. It is important to use these blades and notnormal 710 or 720 mm blades from 90-size helicoptermodels. Vario’s 725 mm blades have a wider chord thanthe 710 and 720 mm blades. The wide chord isnecessary to generate the lift required to propel this14-pound model. If regular 710 or 720 mm blades areused, the helicopter will feel underpowered.The model can easily perform loops and rolls. Incapable hands, it can perform challenging 3-D stunts likePiro flips, Funnels, Tail Slides, etc. but at a slowed downpace. For example, with a Freya or a Raptor, usually onecomplete Chaos cycle (one upright 360 Pirouette with aflip into inverted Pirouette and back to the uprightposition again) takes 1 to 2 seconds, but with the Benzin,it takes about 3 to 4 seconds. Of course, the 14-poundBenzin cannot match the agility of lighter 90-sizehelicopters. For example, the Benzin is not good atdoing Tick-Tocks or Collective Shuffles, which require atremendous power-to-weight ratio. However, the hugeBenzin is fantastic at performing large and gracefulmaneuvers. When the Benzin trucks down the runwayat 60 mph and does a slow roll ten feet off the deck, itis an impressive sight.The Benzin Acrobatic is very stable in flight whenflybar weights or heavier paddles are used. The modelsits there steady, in hover, like a sleepinggiant. On its first flight, the BenzinAcrobatic showed no tail fin shaking orvibration. The engine ran silky smooth andthe main rotor blades required no balancing.Not sure if we were just lucky, or all Zenoah23 cc engines from East Coast Vario comethis well balanced. Instead of using gasolinefrom a gas station, my local group prefersusing Coleman brand kerosene lantern fuelmixed with three percent 2-strokemotorcycle oil. The best oil that my friendand I have found is the Castor 927 highperformance 2-cycle oil produced by MaximaRacing Lubricant in Santee, California. Seewww.maximausa.com.We like Coleman kerosene instead ofregular automobile gasoline because kerosenemakes the engine run clean with no smoke andthe engine sings at a constant note, with nodetonation. Try it and you will discover itworks better than gasoline. It is moreexpensive than gasoline, but still cheaper thanglow fuel. Our mixture of Coleman fuelprovides a longer flying time than glow fuel because itonly contains 3 percent oil, while typical 30% nitro glowfuel contains 30% nitromethane, 20% oil, and only 50%methanol alcohol. Alcohol is what provides the energy,the oil is only for lubrication and causes smoke, and thenitromethane is an oxidizer to give power. In a keroseneor gasoline mixture, 97% is fuel and only 3% is oil. TheBenzin Acrobatic can easily fly for 30 minutes, nonstop,on one fill. In addition, there is no greasy residue towipe off. A gasoline engine powered helicopter kitROTORY53

maybe expensive to purchase, but it saves fuel costs.The Zenoah 23 cc engine is slightly cheaper than a YS91 or OS 91 engine. The Vario Benzin muffler at $261is more expensive than mufflers for the YS 91 or OS91. On the other hand, there is no need for anelectric starter or glow battery. The trick to startthis gasoline engine is to choke the engine by fullyclosing the carburetor opening then, pull the recoilstarter twice. Then open the carburetor slightly andthe engine will start on the next pull.I highly recommend buying the plastic Quick 2 Mixplastic mixer bottle from Maxima. This plastic bottlehas a scale printed on the back of the bottle to allowyou to get any mixture ratio you want. For a brandnew engine, it is best to use the 32 to 1 ratio shown onthe bottle. That means, pour 32 parts of kerosenefuel to one part of oil into this bottle, then close thecap and shake it like a Martini for few seconds. I needto repeat this process a few times to fill up a onegalloncontainer, which I carry to the flying field.If you do decide to get a gas helicopter, make sureto purchase some Tygon gasoline fuel line, special fuelfilter, a canister designed for gasoline, and a handcrank pump designed for petrol fuel. Standard siliconefuel line for glow engines will not work. Joe Howard ofEast Coast Vario will be happy to explain what itemsyou require. Sullivan Products in Maryland makes avery high quality hand pump for gasoline fuel andkerosene.To learn more about the Benzin Acrobatic, go towww.eastcoastvario.com and order a hard copy of the2005 Vario catalog. This full color catalog is 51454ROTORY

VARIO BENZIN FACTS☛ Two-stage main gear 6.72: 1☛ 25 mm tail boom☛ Ball bearing supported stainless steeltail drive shaft☛ Carbon fiber tail rotor control linkage☛ Aluminum tail rotor gearbox housing☛ 0.8 modulus tail rotor bevel gear☛ Aluminum vertical stabilizer☛ Fiberglass canopy with carbon fiber screen☛ 12 mm diameter main rotor shaft☛ Swashplate for 4-point or 3-point eCCPM☛ Rotor head with aluminum center piece☛ Reinforced glass filled nylon blade grips☛ Ball bearing supported mixing arms☛ Fiberglass tail rotor bladespages! It contains technical descriptions and thousands ofcolorful pictures of all Vario pod-and-boom and scalehelicopters. This is absolutely the best RC helicopter onlycatalog in the world. I think other RC helicoptermanufacturers probably agree too. To recuperate thecost of producing this informative catalog, Vario has tocharge $20 for it. It is worth every penny. Even if you donot plan on getting a Vario model it is still a pleasure toread-through. Finally, Vario helicopters are notinexpensive. They are not aimed at the mass market, theyare for people who appreciate unique designs and finequality; like the AMG for car buffs.RMFor Further Information:www.eastcoastvario.com508-520-1867ROTORY55