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Written by Rob Dehner
Heinemann’s Hot Rod makes a great electric jet
Product review
As seen in the November 2017 issue of
Model Aviation.



Bonus Video


Specifications

Model type: PNP EDF jet
Skill level: Intermediate/advanced
Wingspan: 37 inches
Wing area: 372 square inches
Airfoil: Delta planform wing
Length: 56.3 inches
Weight: 77.6 ounces
Power system: 80mm EDF
Radio: Minimum six-channel recommended
Construction: EPO foam
Covering/finish: Matte Navy gray over matte white
Price: $329


Test-Model Details

Motor: Freewing 3530-1850 Kv brushless outrunner
Battery: Admiral 6S 22.2-volt 4,000 mAh and 5,000 mAh (4,000 to 5,200 mAh with minimum C rating of 35C recommended)
EDF: Freewing 80mm with 12-blade impeller
Speed controller: Freewing 100-amp brushless with EC5 connector
Flight duration: 3.5-minute flights with 4,000 mAh battery


Pluses

• Nimble performance, efficient power system, excellent power-to-weight ratio.
• Includes both USAF and USMC waterslide graphics schemes, removable stores (two drop tanks, two AGM-12 Bullpup missiles), and removable 20mm cannon barrels and refueling probe.
• Excellent roll, climb, speed, and takeoff characteristics without sacrificing stability.
• Scale landing gear and detailed and functional split flaps.
• Multipin interface boards for easy removal of wings.
• Ball-link connectors on each hinged control surface for crisp performance.


Minus

• The nose gear strut is long and might not perform well or hold up to uneven grass or bumpy surfaces.


Product Review

Talk around the flying field and in the online forums made it abundantly clear that a new Freewing 80mm Scale electric ducted-fan (EDF) jet was on the way. Many jet pilots were hoping that the new EDF would be an 80mm A-4E/F Skyhawk. Nicknamed “Scooter,” this Vietnam-era warbird was designed by Ed Heinemann in the 1950s and focused on low-cost, outstanding performance, and a straightforward, durable design.

The famed Heinemann’s Hot Rod boasted a scorching 720° roll rate per second (two complete rolls per second), exceptional subsonic speed, and maneuverability that endeared it to many a military aviator.

The appearance of a large, Plug-N-Play (PNP) 80mm A-4 on the Motion RC website, festooned in either U.S. Marine Corps or U.S. Navy graphics with an included scalelike, removable dorsal blister held firmly in place by four strong magnets and plastic guide pins, had many EDF jet pilots jumping for joy!

An initial walk-around of this new EPO foam model reveals how successfully Freewing has rendered the scale lines and unique details of the full-scale aircraft. The model includes an accurately represented plastic molded/painted refueling probe and 20mm cannons, both of which are removable, and large outboard ailerons.




The EPO foam airframe comes out of the box prepainted and ready to accept one of the two included graphics schemes. A full complement of underwing armaments comes with the kit.


Freewing did a commendable job of reproducing the manner in which the ailerons blend into the wingtip area. This attention to scale detail also manifests itself on the elevator surfaces. The result is a truly accurate scale silhouette. A matte Navy gray color covers the upper surfaces, and a matte white covers both sides of each control surface and the underside of the model.

Intakes, fairings, antennae, tailhook, under-wing pylons, and the inclusion of six small, plastic leading edge (LE) aerodynamic “fences” add to the scalelike appearance. Each of the two jet intakes is framed in smooth red plastic, which adds a nice finishing touch in the appearance department and improves the foam composition airframe’s durability.

Scale main gear that rotate 90° before fully retracting into molded wheel bays grace the underside of the delta wing. Also on the underside is an example of a new feature for Freewing aircraft: thinly molded plastic split flaps. The flaps use plastic hinges, are painted red on the inside, and include accurate scale surface details.

Freewing even adds a convex molding that, with the flaps fully lowered, mates into the aft portion of each main gear fairing. Hardcore A-4 aficionados might lament the lack of functional LE slats on the model.

All servos are 9-gram metal gear, except the single elevator servo that is a beefy 17-gram metal gear. Each elevator surface is connected by an inconspicuous plastic spar. This is a different approach from other Freewing aircraft, which typically rely on two servos for each elevator surface.

Wrenching a little on each elevator surface reveals no indication of differential slop or looseness. Every control surface has quality metal pushrods and uses plastic hinges. Ball-link connectors are used on all servo horns. This hardware is a must for any intermediate-to-advanced model! Bravo to Freewing for taking its aircraft in this direction.

A slightly elongated nose gear strut results in the Freewing A-4 sitting on its landing gear in a manner that is similar to the full-scale aircraft. The small nose cone is easily removed from its magnetic holders and the tip is molded plastic.

The kit includes two accurately represented large EPO foam fuel tanks. These tanks were often used on the full-scale aircraft and they do justice to the Freewing A-4’s scale silhouette.

Also included are two AGM-12 Bullpup missiles. All stores are easily added to or subtracted from the A-4 via four underside stores pylons and associated magnetized fasteners.


Assembly

Assembly is straightforward, with both wing halves, elevator, and vertical stabilizer going together using the supplied screws. The kit includes the requisite tube of contact-style glue. It can be used to attach the antennae, fences, stores pylons, tailhook, and exhaust nozzle.




This PNP kit includes a silky-smooth 80mm Freewing EDF power system and assembles using fasteners and adhesive.


To easily remove the wing, Freewing uses multipin boards to aggregate aileron, flaps, and landing gear servo leads. The manual provides detailed instructions on pushrod/clevis/control horn setup with low- and high-rate settings for all control surfaces. The manual also includes recommendations for setting the flap deflection and elevator mixing in a pilot’s transmitter. It is recommended that modelers follow these instructions verbatim.

In connection with attaining the correct center of gravity (CG), there is an addendum in the manual that states that loading stores (the fuel tanks and/or missiles) will cause the CG to move slightly aft. To counter this, pilots should add their desired stores, check the CG, and then make any appropriate adjustments by repositioning the battery in the fuselage. The battery tray is lightweight wood stock. Pilots should mark the wood with a pen for the correct CG location when using different size batteries and also mark any CG differences resulting from stores options.

Add a receiver, secure a six-cell 4,000 to 5,200 mAh battery (there is plenty of room) in place with the supplied hook-and-loop strap, snap the spring-loaded, latch-equipped canopy in place, and this A-4 is ready to fly.


Flying

With setups and rates settings replicated according to the manual, high rates were selected for everything except the elevator. Thirty percent exponential was programmed all the way around. When performing the maiden flight on a new EDF, underwing ordnance can often improve visual orientation and even improve stability. With that thought in mind, the AGM-12 Bullpup missiles were loaded to the outer pylons.

A freshly charged 35C Admiral 6S 4,000 mAh battery was loaded all the way forward in the fuselage and the CG was verified. Pre-maiden flight thoughts that jet pilots might find themselves musing about include whether the nose-high posture of the A-4 will enable premature rotation during takeoffs and whether the relatively small delta wing, equipped with large outboard ailerons, coupled with an airframe that appears to have a higher CG, will create a model that is twitchy on the ground and dynamically unstable aloft.

The runway at the local club is constructed of a typical geotextile material and is relatively smooth. Slowly advancing the throttle spun the 12-blade Freewing impeller to life and created an incredible-sounding metallic whine and whoosh. The A-4 tracked straight and true down the runway, and with a little back elevator applied, transitioned into a clean rotation with a positive rate of climb.

The A-4 showed no sign of springing into the air on its own because of its nose-high stance. Many of the Freewing EDF jets are excellent at storing energy in the form of airspeed and do not necessarily depend on an excess of raw thrust.

At medium altitude, aerobatic maneuvers can be initiated at half throttle. Half Cuban 8s and full Cuban 8s, when performed in this manner, allow the model to zoom over the top without a hint of stall or elevator mush from an excessive loss of airspeed. Inverted flight requires little corrective elevator input. The A-4 feels as though it is on rails when performing full-flap, low-altitude passes on the deck. Aileron rolls at a mere half deflection of the right stick will cause this A-4 to perform some incredibly crisp, amazingly axial, and almost blindingly fast rolls.




After it is trimmed out, this jet rotates into the air on takeoff in a scalelike manner. A small bump of up-elevator is all that is required for liftoff.


The 80mm fan sounds smooth right out of the box, with no audible undulations, lack of power, or indications of imbalance at any throttle setting. Elevator response is precise, with the 17-gram metal gear servo capably doing its job.

Pilots will want to play it safe and start the transition into the landing pattern at approximately 31/2 minutes into the flight. Best practices for landing include dropping the gear and a first notch of flaps when on the downwind leg. A wide, gradual descent and decrease of power/altitude during the downwind leg and on through to base and final works best. Keep the turns shallow, with a little rudder added. The outline of this Vietnam War-era jet coming down the pipe with a steady rate of descent and constant angle of attack is amazing.

Decrease the power and the A-4 will touch down smoothly with plenty of runway left. Pilots need not feel concern that the scale split flaps are all drag and no lift. Freewing got the wing area and camber right and the result is a jet that is predictable and even slightly floaty on final approach. A 31/2-minute flight saw the 4,000 mAh six-cell LiPo battery with roughly 30% capacity left.


Conclusion

The 80mm Freewing A-4E/F Skyhawk, the latest Vietnam-era EDF in the Freewing lineup, is what many EDF enthusiasts have been waiting for. It has a big 90mm feel to it and an imposing presence in the air and on the ground. This A-4’s shortcomings are difficult to find. Although the main gear is large enough for operations from unimproved fields, the length of the nose gear and smaller wheel size could make grass operations slightly difficult.

The included military waterslide graphics look great, but pilots might wish to apply a coat or two of water-based polyurethane clear coating to help keep them firmly in place. And the large size of this 80mm airframe fairly begs for additional nomenclature markings!




Scalelike details include a tailhook, removable gun barrels, and a removable refueling probe. Pilots can choose to fly the A-4 with the magnetically retained avionics hump in place, effectively and instantly transforming the Skyhawk between an E and F variant.


This A-4 is a confidence-inspiring, scalelike performance machine. Any pilot with basic radio programming skills will have no trouble dialing up or down the desired level of performance commensurate to his or her piloting ability. Freewing and Motion RC have done a service to Scale aircraft modeling by designing this A-4 and remembering that durability, simplicity, excellent performance, and reasonable cost have their place. Heinemann would applaud!

—Rob Dehner
ofthesun5615@rocketmail.com


Manufacturer/Distributor:

Motion RC
(224) 633-9090
www.motionrc.com






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