Written by Jon Barnes Jet excitement at a wallet-friendly price Product review As seen in the Summer 2018 issue of Park Pilot.
Specifications:
Type: EDF-powered jet Wingspan: 20.9 inches Length: 31.5 inches Skill level: Intermediate Needed to complete: Minimum four-channel radio and receiver with delta mixing; 3S 1,000 to 2,200 mAh LiPo battery Weight: 12.5 ounces Flight time: 3 to 4 minutes Price: $98 Info: motionrc.comFeatures:
>> Costs less than $100 >> Dynamically balanced five-blade EDF fan for efficient power >> Minimal assembly >> Seldom-modeled Cold War-era jetProduct review
>> The F-105, nicknamed the Thud by its crews, was a supersonic fighter/bomber capable of achieving Mach 2 speeds. Both the F-8 and F-105 harken to the 1950s as Cold War-era jets, and both aircraft qualify as lesser-modeled subjects. The EPO-foam airframe comes out of the box prepainted in a silver scheme, with a nice quality set of preapplied U.S. Air Force graphics. The Native American nose art and the insignia adorning the green-striped vertical stabilizer identify this Thud as a member of the 4th Tactical Fighter Wing, 335th Tactical Fighter Squadron out of Seymour Johnson Air Force Base in North Carolina. Access to the Freewing five-blade 64mm EDF (electric ducted-fan) unit and 30-amp ESC is gained through a removable fastener-retained foam hatch on the underside of the fuselage. The removable canopy hatch is held in place with a spring-loaded release pin. Supply air for the EDF unit is provided by means of a pair of functional, scalelike inlet ducts that completely capture the trademark angularity of the F-105’s inlet ducting. Given the relatively small area of the scale inlet ducting, several auxiliary air inlet ducts are used to supply additional air. Pilots with limited hobby budgets will not only enjoy the roughly $100 price tag of the model, but also the fact that completing it can be done using inexpensive components. Those who use Spektrum (horizonhobby.com) radio gear will be able to use an inexpensive Spektrum AR400 four-channel receiver.
This kit has a low parts count and features a fantastic, factory-applied paint job and U.S. Air Force graphics. It can be assembled in less than an hour using either contact adhesive or epoxy.
Although Freewing suggests a relatively wide range of LiPo batteries that are acceptable for powering this jet (1,000 mAh to 2,200 mAh), pilots who like their models lightweight and their wallets heavy will probably go with the typically inexpensive three-cell 1,000 mAh to 1,300 mAh packs. This tiny Thud employs a unique method of mechanically coupled ailerons and elevators for primary control surfaces. This results in an airframe that only requires two 9-gram servos. Neither a rudder nor landing gear is included on the model. Given the jet’s coupled control surface configuration, a radio system that is capable of doing a delta mix is required. Although the current trend in foam-composition models favors glueless assembly, the Freewing F-105 airframe will require pilots to use an appropriate adhesive. Contact-style cement plays nicely with EPO foam and gives pilots a little extra time to properly position the pieces before the glue sets. Pilots might want to take a few moments to thoroughly examine the kit components before beginning assembly. The short strip of plywood used to anchor the ESC apparently became dislodged in transit on the kit provided for this review. A few carefully applied drops of medium foam-safe CA glue, along with a spritz or two of CA kicker, quickly locked it back into place. When determining the best location for the receiver, pilots will notice that the servo leads are long enough to place the receiver to the very forward position in the fuselage. This location prevents all of the under-the-canopy wiring from obstructing the path from the twin inlet ducts to the front of the EDF unit. Some might not be familiar with the unique type of mechanically mixed pushrods/control surface geometry used on this model. The assembly manual provides specific instructions, with accompanying sketches, to help pilots properly install the aileron and elevator pushrods. The recommended control throws are also included in the assembly instructions, along with the recommended transmitter settings for both low and high rates. The small-diameter, twin-elevator pushrods are quite long out of necessity. In an attempt to limit excessive flexing, Freewing routes them through short sections of slightly larger-diameter tubing that are glued to the fuselage near the servos; however, the aft part of the elevator pushrods, which are not contained in the tubing, are subject to excessive flex at larger commanded elevator deflections.
The 4,500 Kv brushless outrunner makes efficient use of a three-cell 1,600 mAh battery. The 64 mm impeller, although limited to five blades, sounds surprisingly smooth and balanced.
The flexing results in compromised and imprecise elevator response and can also inhibit pilots from attaining the maximum available elevator deflection. Pilots can effectively mitigate this issue by using scrap servo horns, positioned somewhere in the middle of the length of the elevator pushrods subject to flexing, as supplemental pushrod guides. This 64 mm EDF jet comes out of the box without landing gear, so all flights will begin with a hand toss. The F-105’s shoulder-mounted wing configuration all but demands that pilots launch it with an overhand toss. Although pilots who are not accustomed to the art of the hand launch might find themselves nervous at the prospect of throwing an EDF into the air, adherence to the basic tenets of Hand Launching 101 will stack the odds in favor of success. Keep the model’s wing loading as lightweight as possible by using a 1,000 mAh LiPo battery pack on the maiden flights. Confirm that the model balances at the factory-recommended CG (center of gravity) and have an assistant perform the first launch—preferably someone who has proven proficiency in hand launching models. Run the throttle up to at least 75% and give the model a firm push forward directly into the wind. Aim for a point slightly above the horizon and make sure to follow through on the toss. After the Thunderchief has been trimmed out, pilots will have absolutely no problem launching it themselves. For someone using a Mode 2 transmitter, using one’s left hand to make the toss allows the right hand to remain positioned on the transmitter in order to immediately make any needed corrections to the pitch and roll axis. The world of EDFs is currently dominated by high-blade-count impellers. Although pilots generally prefer the “whooshier,” ear-friendly acoustics produced by these EDF units, they typically require a larger ESC and battery. Freewing’s decision to equip this 64 mm Thud with a legacy five-blade impeller, with its inherently lower current draw, helps to keep the wing loading light and the price point low. Pilots will be pleasantly surprised to find that this lower-blade-count fan does not sound half bad. This is no doubt in part because the Motion RC product listing for this model indicates that the Freewing 64 mm EDF is dynamically balanced at the factory. Although the calculated 21.9 ounces per square foot worth of wing loading (or a wing cube loading of 25.2) suggests that the Thunderchief would best be flown by pilots with an intermediate to advanced skillset, the numbers do not always tell the whole story. When flown on a smaller, lighter LiPo battery pack, the F-105 offers a precise, predictable, and stable EDF platform.
There is no mistaking the rakish intakes of the F-105 Thunderchief! Keeping much of the receiver and servo wiring tucked forward and out of the airflow will allow the functional inlets to feed the fan with the cleanest, most undisturbed air possible.
The thrust produced by the stock five-blade 64 mm power system allows the little Thud to handily cruise around the pattern at throttle settings as low as 50%. Even at slower speeds, this model demonstrates a surprising amount of stability. Rolls are axial and quick when performed on high rates. When it is time to land, pilots will appreciate the thick, clear plastic landing skid that is designed to protect the EPO foam fuselage when landing on rough grass. The large ventral fin at the rear of the fuselage encourages pilots to hold the F-105 off as long as possible. Slowing the model as much as possible when slipping through ground effect on the way to touchdown is the best way to safely bring this aircraft back to Earth. Given the model’s ability to use battery packs ranging in size from 1,000 mAh all the way up to 2,200 mAh, each pilot can determine his or her personal comfort zone in the delicate balance between longer flight durations and heavier wing loading. The latter option unavoidably includes a higher net stall speed and more challenging hand launches. EDF enthusiasts who gravitate toward obscure, infrequently modeled jets are sure to enjoy Motion RC and Freewing’s collaborative creation of a new series of nicely priced 64 mm EDF jets. Pilots who are hungry for yet more aircraft in this series will be pleasantly surprised by the plethora of unique models reported to be making their way down the development pipeline. An optional set of steerable, fixed landing gear can be purchased for $10. Although it somewhat detracts from the F-105’s pleasing scalelike aesthetics, the gear set will allow pilots spooked by the thought of hand launching their jets to perform conventional rise-off-ground departures and arrivals. Should a pilot’s Thud go thud, Motion RC stocks the spare parts needed to get it back into the air! -Jon Barnes [email protected]
Article:
