 Electric Ducted Fan Basics
by Tom Atwood
Great Planes Hyperflow 370 EP Ducted Fan, sold with motor (Part No. LXLXA3), Price—$29.99. This unit comes with a 370BB brushed motor, and can be used with a 20mm or 24mm brushless inrunner motor. The unit includes additional stator vanes to straighten airflow for higher performance, brushless motors.
In recent years, advances in motors, batteries and EDF design have enabled electric jets to fly efficiently and fast.
Important factors for good performance include properly contoured rotors, a very small clearance between the rotor tips and the inside of the ducted fan housing, right-sized intake and outlet openings, and even the “lip shape” (contour of the intake perimeter) is important.
If the intake is too large, it can increase drag and decrease efficiency; the intake for the Great Planes HyperFlow fan, designed to fly efficiently at 56 mph, is 129% of the fan’s swept area.
A larger exhaust outlet will increase thrust and decrease airspeed—and vice versa.
The HyperFlow has an outlet area that is 99% of the fan’s swept area. A smooth duct profile with no obstructions can increase thrust by as much as 40%.
For details on the HyperFlow unit, search for part number LXLXA3 at www.towerhobbies.com, and be sure to check out the manual.
 BVM ELECTRA
BOB VIOLETT MODELS
www.bvmjets.com, (407) 327-6333
This is the biggest, baddest, most impressive production EDF on the planet, the Bob Violett Models Electra. Powered by the BVM VioFan, the Electra can reach speeds of 160 mph.
To endure the forces generated at such speeds, the Electra features a fiberglass fuse with carbon fiber and Kevlar reinforcements. 3/16-in. landing gear is included and, as you’d expect on such an aircraft, the Electra has steerable nose gear and full retracts. (Part No. E2000)
Price—$1,495, airframe (visit www.bvmjets.com for details on VioFan power system alternatives)
 A-10 WARTHOG
ELECTRIC JET FACTORY
www.ejf.com, (520) 579-5609
If you’re looking for a larger, more substantial A-10 that won’t break the bank, EJF’s 51-in. wingspan A-10 may be your hot ticket. With a fiberglass fuse and dual 70mm ducted fan units, the Electric Jet Factory A-10 comes with fixed landing gear and a gray finish. A less expensive laser-cut kit with a 41-in. wingspan is also available for 70mm EDF units. Fiberglass ARF
(Part No. A10ARFGrey) Price—$279.99; Laser-cut kit (Part No. EJF70mmA)
Price—$149.99
 F-15 STRIKE EAGLE
GWS
www.gwsus.com, (909) 594-4979
If you’ve ever wanted a scaled-down version of the F-15 Strike Eagle, this new kit from GWS may just be your next aircraft. With a wingspan of 35.4 in., a length of 41.3 in., and a flying weight of 30–35 oz., the F-15 offers great performance with twin ducted fan units and fully functional control surfaces. (Part No. GWAEO024D)
Contact GWS for pricing.
TWISTER ARF
MULTIPLEX
www.multiplexusa.com
(858) 748-6948
If you’re an intermediate to advanced pilot looking for a nice EDF with crisp performance, the Multiplex Twister is a new 3-channel sport EDF that is easy to fly, has plenty of punch, and can be in the air in as little as a couple of evenings.
With a 33.5-in. wingspan and 46-in. length, the Twister is best suited for use at a dedicated flying field. An assembled and balanced 69mm fan unit and brushless motor are included. Radio, servos, battery and ESC are required for completion. (Part No. M214222)
Price—$189.99
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