Hacker-Model Fun Master Attack EPP Foam ARF


Written by Terry Dunn
A durable everyday flyer
Product review
As seen in the Spring 2017 issue of Park Pilot.


Bonus video


Specifications

Type: EPP foam ARF
Skill level: Intermediate
wingspan: 47.2 inches
length: 37 inches
weight: 29.5 ounces
price: $99.99
info: www.towerhobbies.com


Features

High-quality, prefabricated airframe parts
Super-tough construction
Fun, diverse performance range


Product review

It’s hard to deny the joys of flying a simple, well-designed sport airplane. You know the kind of model that I’m talking about. It’s probably not the fastest, best-looking, or most aerobatic model at the field, but it is rugged, dependable, and predictable. Although it might not do anything great, it does many things really well.

The Fun Master from Hacker-Model is one of those airplanes. It is dead simple, tough, and has a super-wide flight envelope. It’s a jack-of-all-trades that is adaptable to different flying conditions and different pilots.

The Fun Master kit is unique in many ways. All of the airframe components are made from EPP foam with integrated plywood stiffeners and plastic hardpoints. The control surfaces use live hinges with precisely cut thin foam.

Rather than stickers, all of the factory-applied graphics are printed onto the surface of the airframe. Even the recommended glue is a deviation from the norm. Keep your CA and epoxy on the shelf. This kit uses hot glue.

Another unique aspect of the Fun Master (and all Hacker-Model kits) is that it is manufactured in the Czech Republic. All of the parts are well made and the preassembled components are perfectly aligned. Even on a simple foamie such as this, it is a treat to work with a kit that is clearly a notch or two above average in quality.




The Fun Master is made of prefabricated foam parts. Overall quality is definitely above average.


Hacker-Model includes a multilingual instruction manual with black and white photos accompanying every step. Assembly begins by prepping all of the servos with screw-lock connectors for the pushrods. The Futaba S3114 servos (futaba-rc.com) that I used are slightly smaller than the precut servo bays in the wing, but I had no trouble securing them in place with hot glue.

I like that the wing has an integrated channel for routing the servo wires into the fuselage. The Futaba leads are barely long enough to reach the receiver, so I decided not to add any extensions. If you plan to unbolt the wing for transport and storage, you might want to add 3-inch extensions on the aileron servos to make things easier.

The elevator and rudder servos fit loosely in the fuselage cutouts, but again, I was able to lock them in place using hot glue. I used 12-inch servo extensions for both of these servos and they were the perfect length. The pushrods for all of the control surfaces have Z-bends on one end. These Z-bends mate with the factory-installed control horns for a clean and slop-free setup.

Removable foam winglets are included. They are held in place with thumbscrews that thread into the foam wing. Interestingly, the thumbscrews and a few other components in the kit appear to be 3-D-printed parts. Regardless of how the screws are made, installing and removing the winglets takes only a few seconds and they have a significant impact on how the Fun Master flies.




The foam winglets are held in place with thumbscrews. They make a big difference in how the Fun Master handles in the air.


I powered my Fun Master with a RimFire 400 brushless motor (electrifly.com), Great Planes Silver Series 25-amp ESC (towerhobbies.com), ElectriFly 3S 2,200 mAh 30C LiPo battery, and an APC 9 x 6E propeller (apcprop.com). Unfortunately, the kit’s included spinner didn’t fit over the APC propeller, so I left if off. If you’re considering a slow-flyer-style propeller, be sure that your setup does not exceed the propeller’s maximum rpm rating.

The mounting plate for the RimFire 400 does not align with the predrilled holes on the Fun Master’s firewall. I drilled new holes and used short spacers to mount the motor. The hub shims included with APC electric and slow-flyer propellers make perfect spacers for this job. All of the other power system components fell into place.




The ElectriFly RimFire 400 is well suited to the Fun Master. Terry Dunn only had to drill mounting holes in the firewall for a perfect fit. The spacers behind the motor mount are APC propeller shims.


The battery is secured in its compartment using a plastic clamp that engages with notches in the fuselage’s plywood reinforcement. It is a simple and effective system. I was concerned about misplacing the clamp at the field or in my shop, so I used a short piece of thread to tether it to the landing gear.

I like to use the Fun Master as a platform to capture in-flight photos and video. Some of my early onboard video footage revealed that the vertical stabilizer was vibrating during flight. Although it never showed any signs of structural fatigue, I decided to head off any potential problems by adding simple braces. The braces are 6-inch sections of 1/16-inch fiberglass rod that I stuck into the tail feathers and glued into place with thick CA. I’m sure bamboo skewers would work equally well.




An ElectriFly 3S 2,200 mAh 30C LiPo fit perfectly in the battery bay. Note the tether that Terry added to the clip-on battery retainer.




Terry added simple braces on the tail feathers to prevent the vertical stabilizer from vibrating in flight.


I use a Tactic TTX850 transmitter and TR625 receiver (tacticrc.com) to control the Fun Master. Although the footprint of the TR625 fits nicely below the wing saddle, the area is not deep enough to accommodate the receiver’s vertically oriented servo connections. I used a small sanding drum in my Dremel tool (dremel.com) to hog out some of the foam so that I could lower the receiver. This step is probably not necessary for people using a receiver with horizontal servo connections.




Terry deepened the receiver bay slightly to accommodate the vertical servo plugs on his Tactic TR625 receiver.


The Fun Master came together in one leisurely afternoon. I had to add 0.5 ounce of lead beneath the motor to get the center of gravity correct. My completed model weighs 29.5 ounces which equates to gliderlike wing-loading and cube-loading values. I have plenty of power on tap as well. As I headed out for the maiden flight, I was pretty sure that all of these elements would contribute to making the Fun Master live up to its name. I was correct.

Taxiing on paved or unpaved surfaces is no problem, thanks to the Fun Master’s oversized main wheels and steerable tailwheel. Much like the bush planes that this model emulates, it actually seems to prefer operating from rough terrain rather than smooth runways. Just point the nose into the wind and add power when you’re ready to take off. The Fun Master will be airborne within a few feet.

I configured my model with the recommended control throws. On low rates, the model is quite easy to fly. I think the Fun Master would make a fine second model for someone who has conquered his or her trainer. It will still perform mild aerobatics on low rates, but the airplane’s control response is smooth and gentle—no snappy surprises here.

The Fun Master becomes livelier with high-rate control throws. You shouldn’t expect precision aerobatics or hardcore 3-D performance. You can, however, expect a nimble model that keeps on flying no matter what crazy things you might do on the control sticks. Go ahead and try a new maneuver. The Fun Master will forgive your mistakes and quickly recover.

Rolls are slightly barrel shaped rather than axial. The rudder is surprisingly authoritative given its modest size. This is especially true when the winglets are attached, but be aware that rudder input comes with a lot of roll coupling. For instance, knife-edge flight requires plenty of opposite aileron correction and a little bit of down-elevator, too.

The elevator has plenty of authority for loops and inverted flight. Both are easy and fun. You can make your loops short or tall. Vertical performance with my setup is strong, but not unlimited, so plan ahead to make sure you’re carrying a little energy into vertical maneuvers such as hammerheads and stall turns.

I’ve attempted spins with the Fun Master, but my success rate is low. The “problem” is that it’s actually very hard to get the model to stall. It just wants to keep flying. Sure, that characteristic provides benefits elsewhere, but Lomcovak maneuvers probably aren’t in the cards. Snap rolls are quite respectable, and recovery is instant.

Although the Fun Master is capable of flying quite slowly, it can also get moving when you jam the throttle. It displays a good speed range for a park flyer. I think it could be comfortably flown by an experienced pilot off of a baseball, football, or soccer field.

After roughly a dozen flights with the winglets installed, I began logging time with them removed. Their absence makes a noticeable difference in how the Fun Master performs. Aileron response improves in exchange for reduced rudder authority. Roll coupling with rudder input also seems to be tamer without the winglets.

I’ve developed a few preferences now that I’ve spent considerable time flying the Fun Master both with and without winglets. The winglets go on for calm days when I just want to do light aerobatics and cruise around shooting touch-and-gos. If I’m feeling more aggressive, or the wind is blowing, I like the Fun Master to be winglet-free.

Because I connected the Fun Master’s aileron servos on different channels, I am able to experiment with flaperons and spoilerons. These settings are another avenue to widen the performance envelope of a model that already does so many things well. Flaps are fun on calm days when I want to see how slowly and gently I can keep the model airborne. Sometimes I’ll engage spoilerons to help me drop through ground effect and stick the landing.

As you might have guessed, the slow-flying, stall-resistant Fun Master poses no challenges when it’s time to land. It will tolerate all kinds of approaches and landing techniques. The big tires and cushy landing gear help limit abuse to the airframe. In fact, the undercarriage is so springy that it’s actually difficult to avoid bouncing when landing on paved surfaces. My landings tend to look better on grass.

This model is pretty draggy, so you’ll want to make sure that you reserve some battery power to bring it back home for a landing. I frequently work the throttle during my flights. I usually stay airborne for 8 to 10 minutes and I still have some juice left in the battery.

The Hacker-Model Fun Master is a solid, everyday flyer. It is extremely well designed and built, and its EPP foam components make it tough, too. Best of all, the Fun Master has a wide performance envelope that makes it suitable for all types of pilots.




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