Bergen Intrepid Gasser detailed photos, assembly, tips tricks and modifications. Click on the links below to go to specific detailed descriptions and photos. Photos on this page are general in nature, typically covering the assembly and construction of the helicopter and description of the various systems. We will eventually convert this page to employ a thumbnail image preview system so that it loads faster.
Other interesting Bergen pages on our website:
Lifting external loads with the Bergen Intrepid
Videos of the Bergen Intrepid Gasser
Equipment List:
720mm V-blades; Zenoa G230PUH gas engine, quiet muffler (the big round silver-plated one); Futaba GV-1 rotorspeed governor (set to headspeed of 1650, 1675, 1700 - flight selectable); Futaba GY401 heading hold gyro; Futaba S9254 digital servo on tail rotor; Futaba S9202 servos on cyclic pitch, collective pitch and throttle servos; dual Hydrimax 6V NiMH battery packs 2000 mAh each, diode isolated and voltage reduced for the digital servo (recommended 4.8V nominal). Operated with a Futaba 9CHP 9-channel radio connected electronically using the Heli-Chair flight console set-up.
Performance and Detailed Specifications:
coleman 'camp' fuel
empty weight 13 lbs
gross weight in hover 28 lbs (lifted 15lbs dead weight)
[conditions for test: 3,700 ft density altitude, wind 5kts, HOGE]
[HOGE = hover out of ground effect]
fuel capacity 16 fluid oz.
main rotor diameter 63.50"
constant chord length 24.38"
length of blade tip to blade bolt 28.50"
chord at tip 2.50"
chord at blade bolt 1.40"
tail rotor diameter 10.50"
tail rotor constant chord 3.25" (includes radiused tip in measurement)
tail rotor maximum chord 1.10"
tail rotor length of blade tip to bolt 3.70"
main rotor rpm 1600-1700 typical
gear ratio engine to main rotor 6.43:1
gear ratio main rotor to tail rotor 1:4.67
endurance to fuel exhaustion 35 minutes HIGE [hover in ground effect]
endurace estimated 12 minutes at gross weight HOGE
endurance in level forward flight not yet tested
Operational notes:
The Bergen Gasser will hover for about 30 minutes to complete fuel exhaustion. It is capable of lifting 15lbs dead load, and could instead carry 10 pounds payload, 5 pounds extra fuel in a heavily loaded condition, extending flight times to beyond 1 hour. Bergen also offers longer main blades that may increase the efficiency of this helicopter.
Because the helicopter weighs 13lbs, when carrying 15 lbs extra, the fuel consumption could double because the power required would double. This is in a hover, if you are in forward flight, the amount of power required decreases a great deal due to translational lift.
Think quite seriously about an on-board generator. We fly ours with two 6V battery packs, 2000mAh each, that are in parallel. One hour is the maximum endurance of the electrical system. For this helicopter configured with a heading hold gyro and governor (GV-1), the electrical system will draw approximately 3 Amps during flight.
Tips and Tricks (click to see tips photos at end of page):
Support the servo wires that come from the helicopter roll servo (aileron) with an adel clamp (MS21919) to prevent its fatigue and eventual failure. Support both the tail rotor servo cable and again the roll servo wires at the point of pivot for the collective pitch change mechanism (see red arrows in photo). Replace the delicate set screw on the flybar control arms with instead a regular 3mm allen screw. Be sure to screw the flybar paddles far onto the threads of the flybar. If you have the paddles screwed only as far as having the base of the threads at the base of the paddle, the bending loads will be concentrated there. If you screw the paddle further onto the flybar (1/4" to 3/8") it will distribute the bending loads further down the shaft away from the base of the threads where there is a natural stress concentration.
