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Written by Jon Barnes
Horizon Hobby E-flite Viper 70mm EDF BNF Basic With AS3X and SAFE Select
Product Review
As seen in the July 2019 issue of Model Aviation.


At A Glance

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Specifications

Type: Electric ducted-fan jet

Skill level: Intermediate

Wingspan: 43.3 inches

Wing area: 300 square inches

Length: 40.5 inches

Weight: 70 ounces

Power system: 70 mm electric ducted fan

Radio: Minimum six channels required

Construction: EPO foam

Price: $249.99

Test-Model Details

Motor: 2860-1850 Kv brushless inrunner (included)

Power system: E-flite 12-blade 70 mm electric ducted fan (included)

ESC: E-flite 70-amp brushless with switch mode BEC; EC5 connector (included)

Battery: Recommended 6S 22.2-volt 3,300 to 4,000 mAh minimum 30C-rated LiPo (not included)

Radio system: Spektrum DX9 nine-channel 2.4 GHz DSMX transmitter (not included); Spektrum AR636 six-channel AS3X and SAFE Select-equipped 2.4 GHz DSMX receiver (included)

Ready-to-fly weight: 64 ounces using Spektrum 6S 22.2-volt 30C Smart Technology LiPo with IC5 connector

Flight duration: 3 to 5 minutes

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Pluses

  • Tastefully adorned with an eye-appealing, blue/gray/white camouflage color scheme created by Mirco Pecorari’s Aircraft Studio Design.
  • Transmitter-switchable SAFE Select mode can be enabled/disabled while in flight.
  • A fantastic first EDF jet for intermediate-level propeller airplane pilots who are looking to step into the jet age.
  • Sturdy sprung wire struts can capably soak up many of the bumps and bruises of less-improved runway surfaces.

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Minus

  • Color scheme could present orientation challenges on overcast days to pilots with diminished visual acuity.

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Manufacturer/Distributor

Horizon Hobby

(800) 338-4639

www.horizonhobby.com

Bonus Video

The pseudo-military-looking graphics and bluegray camouflage color scheme that Aircraft Studio- Design conjured up for the E-flite Viper gives this model a visually stimulating and exciting-looking in-flight presence!

ONE OF THE MORE prolifically represented and modeled jets in the world of RC aircraft is a ViperJet. This jet has been modeled in an impressive range of sizes, using a variety of mediums and construction techniques. From relatively small, 50 mm electric ducted-fan (EDF) EPO foam-composition park jets to turbine-powered, composite-construction giants, Viper models can be had in a format and price range that is agreeable to the wallet and tastes of assuredly most potential Viper pilots.

RC jet aircraft can generally be placed into one of two categories: Scale or Sport. Although the former genre consists of models that are based on full-scale aircraft, the latter covers models that have no real world, full-scale counterparts—in other words, they are strictly fantasy-based designs. More than a few RC pilots would probably erroneously place the Viper into the Sport category.

This is no doubt due in part to the fact that although full-scale ViperJets exist and have been flown in the real world, a search of the FAA’s online registration database reveals that only five ViperJets that are assumed to be airworthy are in existence today.

Poke around in the long and varied hallways of the internet and you will find that the full-scale ViperJet has all but fallen into a state of unobtainium.

The conundrum in all of this is that if a full-scale Viper flies anywhere near as sublimely as the scaled-down, smaller models of it typically do, it should have been a rave success!

For intermediate pilots whose interests are still firmly planted in propeller-powered electric aircraft and are contemplating a segue into the world of EDF-powered jet models, E-flite has released an ideal vehicle with which to make the journey: the E-flite 70mm Viper!

Available in a BNF Basic version and a Plug-NPlay (PNP) version, this EPO foam-composition model boasts flaps, retractable tricycle landing gear with durable, sprung wire struts, and an extremely lush-sounding 70 mm, 12-blade EDF power system.

using 11 identical size and length fasteners to assemble
01: Using 11 identical size and length fasteners to assemble the airframe eliminates any chance of confusion and makes for fast assembly. Programming one’s transmitter to take full advantage of all of the model’s features will take more time than actually assembling the airframe.

when making a full throttle pass
02: When making a full throttle pass, the 12-blade, 70 mm EDF offers some of the most acoustically rich and lush-sounding "whooshes" to be found in this size and class of EDF jets!

when combined with the gyroscopically anchored
03: When combined with the gyroscopically anchored AS3X stabilization that comes embedded in the included Spektrum receiver, the use of ball link-style connectors on the control surface end of all of the pushrods gives this jet impressive, laser-sharp in-flight tracking.

The rarity of real-world ViperJets means that there are only a few authentic, scale color schemes to select from when rolling out a new Viper model. Instead of falling back to one of the most commonly used, copper-colored Viper schemes, E-flite commissioned Mirco Pecorari’s AircraftStudioDesign to come up with a unique scheme that faithfully bears witness to one of the original marketing phrases that was used to introduce of the full-scale Viper to the world: "the Personal Fighter Jet."

The snappy-looking scheme features a multihued gray camouflage pattern on the lower half and bottom of the airframe, and a blue-on-white striped scheme with red highlights on the topside.

Completion of either version of the model will require a Spektrum DSMX/DSM2-compatible, six-channel-minimum transmitter and a six-cell, 22.2-volt-minimum, 30C 3,200 to 4,000 mAh LiPo battery. Although pilots can save a little money by opting for the PNP version, which omits the Spektrum AS3X/SAFE Select-equipped six-channel sport receiver, read on to see why I recommend that pilots who are new to the world of EDF jets go with the BNF receiver-equipped version.

Assembly

Although the 56 pages that make up the included black-and-white paper assembly manual suggest that a serious block of time is required to assemble the Viper, nothing could be further from the truth (the manual includes four different languages). In fact, physical assembly of this BNF Basic kit involves nothing more than attaching the vertical and horizontal stabilizers and the one-piece wing to the fuselage.

Before starting the Viper’s assembly, perform a little preventative maintenance by removing the control linkages from all of the control surfaces and carefully flexing the control surfaces to loosen them. Ball link-style connectors are used all the way around. The best way to remove and reconnect them without accidentally damaging them in the process is to use a pair of ball link pliers. The current trend in EDF jets has many manufacturers using ball link connectors on their aircraft, so pilots who do not own a quality pair of pliers should purchase one.

Adhesives are not required to assemble the Viper airframe components. The aircraft is held together with fasteners. E-flite makes this process an absolute no-brainer in that the 11 fasteners used to assemble the Viper are identical! Pilots wielding a quality 2 mm screwdriver should have the Viper airframe completely assembled in 10 to 15 minutes. More time will typically be required to bind the onboard Spektrum AR636 receiver and complete the required transmitter programming.

A single sheet advisory that is included in the Viper’s paperwork encourages pilots to check for the latest assembly manual addendums online. I did not find anything online that was not also included in the box.

using a battery toward the low end
04: Using a battery toward the low end of the recommended range of 3,300 to 4,000 mAh keeps the wing loading light and allows the Viper to perform at its best. As a pilot gains familiarity with how the model behaves in the air, he or she will probably want to experiment with shifting the pack rearward.

this serpents underbelly features a striking
05: This serpent’s underbelly features a striking, multihued Arctic camouflage color scheme. In-flight orientation on grayer days could prove challenging for pilots with less visual acuity.

Even more useful and of significant interest to pilots will be the video on the Horizon Hobby website that walks them through the process of binding the model so that SAFE Select mode is enabled. The video details how to select and activate the transmitter switch that a pilot wishes to use to control this mode. Although the paper manual also includes this information, the video will probably be of more assistance in helping a pilot breeze through this part of the programming.

Flying

The recommended six-cell LiPo battery flight pack for the Viper ranges in capacity from 3,300 to 4,000 mAh. Pilots using packs in the 3,200 to 3,300 mAh range will want to locate them approximately a thumb’s width aft of the forward edge of the battery bay for the maiden flight. It might be possible to shift it farther back on subsequent flights as the pilot becomes more comfortable with the model. Larger-size packs (3,700 to 4,000 mAh) will need to be pushed to the rear of the battery bay. A 4,000 mAh pack might be a tight fit, depending on its form factor and overall dimensions.

For Viper pilots who are nervously anticipating their first EDF jet flight, seeking out the hands-on assistance of a local qualified jet pilot is the best way to stack one’s odds for success and avoid damaging this beautiful model on its first flights.

Pilots who are determined to earn their jet wings on their own should activate the Viper’s SAFE Select mode and write the following phrase on a piece of paper 100 times: "Do not forget to pull the throttle back!"

flight envelope

Although the switchable SAFE Select system can simplify the workload that this aircraft presents to newer jet pilots, pilots will still need to responsibly manage the throttle—that is, the velocity of the model—at all times. One of the most common mistakes made by newer jet pilots when maidening a new aircraft is to leave the jet at or near full throttle after taking off. There are two reasons why this could quickly get a pilot in trouble.

One, with the bank limiting that is part of the SAFE Select mode when it is activated, the Viper will require a good amount of space to complete turns. Two, if you leave the throttle at full, the Viper will quickly accelerate to triple-digit speeds. The combination of these two factors could easily result in a pilot allowing the Viper to quickly get beyond the limits of his or her personal visual acuity. Additionally, the blue, gray, and white color scheme can make for slightly more challenging in-flight orientation on gray, cloudy days.

After a pilot has the Viper two or three mistakes high, he or she should pull the power back to a more moderate 40% to 60% setting. With the throttle at mid-position, newer jet pilots should have no problem managing and acclimating to the slightly different feeling of flying an EDFpowered aircraft.

The Viper will politely cruise around at such reduced throttle settings, with nary a hint of anything venomous or evil lurking in this slower side of its flight envelope. Drop in half flaps to further explore the slower speed side of the flight envelope.

Pilots who are familiar with other model manufacturers’ renditions of the ViperJet will attest to the outstanding tracking that is typically inherent to this airframe. E-flite’s addition of AS3X, with its well-proven, gyroscopically driven stabilizing influences, endows the Viper airframe with incredibly sharp and precise in-flight tracking.

This jet goes exactly where you point it and remains on track in an almost uncanny fashion! The ball link-style connectors used on the control surface end of the pushrods assuredly contribute to this. They minimize—if not completely eliminate—the amount of backlash present in all control surfaces, contributing to the Viper’s superlative locked-in feel.

Jet-style aerobatic maneuvers are equally crisp when performed, and knifeedge flight is this Viper’s forte for sure. Full-throttle passes result in the 12-blade, 70 mm fan emitting an acoustically gorgeous and lush-sounding whoosh that will be music to most pilots’ ears!

Landings with full flaps substantially reduce the Viper’s stall speed and allow pilots to slow down this jet for landing on shorter runways. Although the Viper’s sprung aluminum landing gear are capable of soaking up the bumps and bruises that can be served up by less-improved runway surfaces, setting it down too hard on landing or stuffing the nose gear into a gopher hole can cause the wire gear to bend.

Pilots who are coming over from propeller-driven electric models will have to acclimate to the typically shorter flight durations of EDF-powered airplanes, although a little moderation on the throttle can and will extend flight durations. Pilots can generally expect flight durations of between 3 and 6 minutes, depending on the battery capacity and throttle usage.

Conclusion

Veteran jet pilots need not thumb their noses at this model because it is marketed as the "perfect first jet." Its triple-digit top speeds and totally locked-in tracking are sure to satisfy even those who are well accustomed to the thrill of EDF jets. The slightly less-costly PNP (receiverless) Viper might be a good fit for an advanced pilot who will likely not use or need to fall back on the embedded SAFE Select system.

For pilots who have yet to spring for their first EDF-powered model, the E-flite Viper is indeed the jet with which to earn your fighter wings. Its notable in-flight stability, and included Spektrum receiver that is equipped with embedded stabilization (AS3X), flight attitude limiting and recovery (SAFE Select) technologies, are uniquely what make this Viper a tame trainer and potent performer!

a great option for aspiring jet pilots


SOURCES:

Spektrum

(800) 338-4639

www.spektrumrc.com

AircraftStudioDesign

info@aircraftstudiodesign.com

www.aircraftstudiodesign.com

1 comments

Please accept from a senior peer a "Well Done ! " for superb flying, video and writing skills. May I suggest a modification to any EDF for truer whoosh and more speed..........add a non-moving air deflector cone in front of the fan hub. The air hitting the high rpm hub is thrown radially out and disrupts the other airflow into the blades. A non-moving cone directs the center core of air smoothly past the hub and blends it into the blades. Besides eliminating the air blower sound, the thrust increases. The down side is that I have seen cheaper EDF blades rev past the burst point. That gets interesting to hear a bang and then silence as the jet becomes a glider.......and when you see nothing where there used to be blades.

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