Hacker Model EPP F6F-5 Hellcat Review Featuring Super Tigre Electrics and GWS Servos - RC Groups

Hacker Model EPP F6F-5 Hellcat Review Featuring Super Tigre Electrics and GWS Servos

Everybody can use a little EPP profile fun flying in their hangar. Hacker Models has created an entire series of colorful WWII War birds. Which one will be YOUR favorite foamie fighter?!



Wingspan:33" (840mm)
Weight:12 oz. (340g)
Servos:GWS Naro +D Digital 10g (3)
Transmitter:JR X9503 DSM2
Receiver:Spektrum 6100e (Rev 1.6 firmware)
Battery:Thunder Power Pro Power 45C 850mAh 3S
Motor:Super Tigre 400 brushless outrunner
ESC:Super Tigre 20 amp brushless
Manufacturer:Hacker Models
Available From:RCBaron and others soon to come
Flight Duration:5-7 minutes

Of the various types of foam used to manufacture model airplanes, EPP may be the most durable of all. Though its appearance is very erose and irregular, it is particularly noteworthy for the way it can be reassembled and repaired after an attack of the dumb thumbs. Capitalizing on this, Hacker Models has been manufacturing a series of aerobatic EPP models for some time now. They have recently added an entirely new product line, in the form of a series of colorful World War 2 EPP profile war birds.

Items required to finish the plane and specs are listed on the side of the box, as are the various planes available

Kit Contents

The Hellcat is available in two different color schemes

In The Box

  • EPP fuselage, wing halves, vertical stabilizer and rudder, horizontal stabilizer and elevators; all hinges integral to the EPP foam
  • Metal stiffener rods for wings and fuselage
  • Clear, plastic canopy
  • Laser cut lite ply motor mount pieces
  • Composite control horns
  • Wooden elevator joiner stick
  • Push rods (rigid inner control rod in outer flexible tube variety for rudder and elevator, short metal push rods for ailerons)
  • Miscellaneous hardware required to assemble kit, including motor mounting screws and quick link connectors
  • Multi-page, multi-language black & white photo-illustrated assembly instructions

Required for Completion

  • 150 watt power system (Motor, speed controller and lipoly battery)
  • Appropriate propeller and prop adaptor/mount
  • Minimum four channel radio system

Included for Review

  • Thunder Power 45C ProPower 3S 850mAh lipoly batteries
  • GWS Naro +D Digital 10g servos (3)
  • Super Tigre 400 brushless outrunner motor
  • Super Tigre 20 amp electronic speed controller


8 page black and white, multi-language assembly manual

There are two indispensable items needed for properly assembling a Hacker Models EPP profile war bird: plenty of sharp hobby knife blades and cyanoacrylate glue in the normal, non foam safe variety. I use accelerator for many of the assembly steps. When cutting into EPP foam, a virgin sharp blade is imperative. I changed my blade fairly often while making my way through the build. Failure to use a sharp blade will result in the foam getting crushed instead of cut. The included paperwork will sufficiently guide you through the process of getting this one from the box to the skies. Another sheet provides detailed completion information, including CG and recommended flight surface throws. The instructions use a different war bird as the model photographed during assembly but it was not very difficult to translate what needed to be done to accomplish the same thing on the Hellcat. One thing I really like about these profile EPP foamies is that the control surface hinges are all integral to the EPP foam, that is, they are all ready to go right out of the box. There is no hinging necessary.


To properly stiffen the EPP fuselage, a pair of soft, metal rods needs to be glued in place. I used a new hobby blade and straight edge to cut shallow trenches along a bias on each side of the fuselage. There are two sets of stiffener rods included in the box. The longer ones are used on the fuselage. Once the shallow cuts have been made, I used a Phillips screwdriver blade to push the rods down to the bottom of the cuts. It always amazes me how EPP foam pretty much consumes whatever you embed into it, rendering the object almost completely invisible. The rods fit into the foam with enough friction that I decided it necessary to apply a little CA at both ends and in two inch increments along the balance of the length instead of in a continuous bead.


The fuselage comes prepared to receive both the horizontal and vertical stabilizers. The horizontal stabilizer slips into the rear of the fuselage first, after which the vertical stabilizer can be glued atop it. The vertical stabilizer also attaches to the rear of the fuselage. I used CA for these steps, accelerating the curing with a few carefully aimed blasts of kicker. Before committing to a permanent attachment, I dry fitted these components to verify that they were properly aligned and square. I was happy to see that no sanding would be necessary, as the fit and alignment was perfect. The two elevator halves become one by means of a square, wooden joiner rod. The control horns are mounted by cutting small slots into the control surfaces, pressing them down into the slots and then making them permanent with a little CA.

Completed tail assembly


The first step in assembling the wing involves making the two halves into one whole. Again, CA is the adhesive of choice for this step. Stiffener rods are also supplied for the wing, with one getting installed topside and the other in the bottom in the same manner as the rods were installed in the fuselage sides. The wing does have a small bit of dihedral, and thus the stiffener rods must be bent to properly follow the contours of the wing. The composite control horns are installed by cutting small slots and CA'ing them in place. Hacker Models eases the installation of the wing to the fuselage by cutting a slot in the under belly, towards the trailing edge of the wing. I ended up cutting another slot near the leading edge and entirely removing this fuselage under belly piece, as slipping the wing into place with the aileron servo glued in place in the fuselage proved to be a little too difficult (additional information and photos in Radio Installation section below). I also thought it best to carve some shallow relief pits into the topside of the wing, for the aileron servo quick links to fit into throughout their entire range of motion. I used a black thick tip Sharpie to color these recesses back into black.

I did not permanently attach the wing to the fuselage until after I had mounted the aileron servo into the fuselage. I would recommend following this same order of solve when assembling this model, as doing so helps guarantee that you have all of the radio and servo components mounted and functional before you glue them permanently into place. Once the wing is glued in place, it becomes impossible to access or remove the aileron servo should it be necessary to replace or adjust it. After the wing is glued in place, the removed under belly pan can be reinstalled and glued back in place.

Radio Installation

GWS Naro +D Digital Servos

I have used the various GWS sub miniature digital servos in several different models over the last few months. So far, I have been duly impressed with the performance of them, especially considering their relatively low street price. The Naro +Ds are a good choice for these EPP profile planes, as there is not an abundance of space available in which to place servos. The instructions provide some recommendations for mounting the receiver and servos in the air frame but again, the instructions specifically detail what it takes to do it to the Hacker Models P-51 Mustang. A little improvising was in order to successfully fit the elevator and rudder servos, plus the Spektrum AR6100e DSM2 receiver, under the canopy as suggested in the instructions. Grab another fresh blade and cut pockets in the EPP foam cockpit area, using the knife to both cut the perimeter and also to fracture the block of foam so that it can be removed. A little hot glue will securely hold them in place.

Space is at a premium, so when it comes to mounting the little AR6100e, I found it necessary to cut and remove a piece of the turtle deck just aft of the cockpit area. I hot glued the receiver in place, carved a relief out in the underside of the removed turtle deck piece for receiver clearance and then set this piece aside for later reinstallation once all of the servos were connected to the receiver.

I was glad that GWS only includes a very short servo lead on the Naro +D servos, as the excess length needs to be bundled and stored somewhere, given the close proximity of the servos to the receiver. I removed a little extra foam alongside the servos and tucked the excess servo leads down into this pocket. Hacker Models includes the required quick links for making the push rod connections to the servo horns. The push rods get slotted down into the fuselage sides in much the same manner as the stiffener rods did during the assembly. It is important to route them so that the push rods have a clean approach to the servo horns and also the control horns on the elevator and rudder, for minimal binding. The GWS Naro +Ds are pretty torquey little servos and though I was a little concerned with the amount of resistance I felt on the installed rudder and elevator push rods, the GWS servos had no problem overcoming this resistance and were still able to center almost perfectly every time.

As mentioned above in the "Wing Assembly" section, I thought it best to cut and remove completely the section of the fuselage under belly that spans the wing, for easier installation of the wing onto the fuselage. The aileron servo gets mounted up into the fuselage, towards the rear of the wing saddle. It will take a little patience and a steady hand to carefully carve out the proper sized pocket for the ailerons servo. It needs to be recessed deeply enough into the fuselage so that the aileron servo horn does not come into contact with the top of the wing. The aileron servo lead needs to find its way up into the cockpit area for connection to the receiver. I used a bamboo skewer to poke a hole completely through the fuselage and then taped the servo lead to it and slowly pulled it through the hole. I mounted the included quick links in the inverted position to create the necessary clearance between the aileron servo horn and its connections and the wing. Once the aileron servo has been mounted in the fuselage, connected to the receiver, mechanically zeroed, and properly programmed in the transmitter, the wing can be permanently mounted to the fuselage.

Power System Installation

Super Tigre 20 amp speed control manual

Super Tigre 400 brushless outrunner manual

Super Tigre came out with a very affordable line of brushless motors and electronic speed controllers recently. I used their 400 size brushless outrunner and 20 amp ESC in the Hellcat. The Hellcat motor mounting system will accommodate either a front or rear mounted outrunner motor. Mounting the Super Tigre 400 required a little engineering in order to get it attached to the nose of the Hellcat.

The first step in getting the Super Tigre to work on the Hellcat involved trimming the tri-lobed aluminum motor mount so it would fit on the ply firewall. I then had to drill a hole in each lobe, as well as in the lite ply firewall. After the motor mount was mated up to the firewall, I applied a little thread lock compound to the three fasteners.

Hacker includes a three piece lite ply motor mount to secure the brushless motor to the nose of the plane. This was one of the few steps in building the Hellcat in which I used epoxy instead of CA glue. Once the epoxy has cured, the firewall is attached to the engine mount using the four included screws. I did have to open the center hole in the firewall up a little to provide more clearance for the rear of the Super Tigre outrunnner.

The Super Tigre 400 outrunner is a very small and lightweight motor compared to other similar motors one could use on the Hellcat. I kept this in mind as I continued to mount the power system components. I figured it wise to keep the speed controller as far forward as possible, and to accomplish this I trimmed the three motor wires very short and soldered them directly to the ESC leads. I removed a little of the foam fuselage where I intended to mount the ESC and hot glued it into the recess. The receiver lead needs to be routed up and into the radio compartment. I cut a shallow channel with my hobby knife and then pushed the lead down into it.

The final step in finishing the power system installation is to grab the prop and attach it to the collet style prop adaptor, and then this assembly to the motor shaft. I started out with a APC Slo-Flyer 10X3.8 prop after reviewing the Super Tigre 400 brushless motor documentations recommended prop sizes.


Hacker Models includes a nice little polycarbonate canopy with the kit. It requires a little trimming with a pair of curved tip scissors before it can be attached to the fuselage. It has molded in framework details and for it to look its best, it t is a good idea to either paint or tape them in. I chose the latter route, using thin strips of black electrical tape to fill in the framework details. Once completed, a few carefully placed spots of hot glue were used to secure the canopy to the foam fuselage.

The final step in assembling the Hellcat involves preparing a mounting location for whatever lipo battery you are going to use. I acquired a pair of Thunder Power Pro Power 45C 3S 850mAH batteries for this project. I measured and marked the center of gravity, as is listed in the assembly instructions, and then placed the battery in the necessary location to achieve this CG. Once it was apparent where the battery needed to go, I set about preparing the location. The Super Tigre 400 brushless outrunner is again considerably lighter than other motors that could be used in this airframe, which results in the battery needing to be located a little further forward than might typically be expected. I did not want to just stick the lipo to the side of the fuselage with hook and loop. I thought it best to get it as close to the center line of the fuselage, for a better longitudinal balance of the Hellcat. I thus carved a pocket out just under the leading edge of the wing. There was not a lot of space to work with in this location but in the end, I was satisfied with how the mounting area turned out. The batteries are almost invisible when mounted in place and they fit snugly enough that I did not feel the need to use any hook and loop to secure them in place.

All finished and ready for its first sortie!


Taking Off and Landing

Ah, the simplicity of hand launching a gearless profile foamy with a power to weight ratio well north of 125 watts per pound. No worries about proper launch technique or form at all... just put the pedal to the metal and release. It really is just that easy. Whether you choose to hold the Hellcat in an underhanded or over handed grip, all that is really required to get her safely aloft is to advance the throttle to at least 75% and let her go! Equipped with the Super Tigre 400 brushless motor and either an APC Sol-Flyer 10x3.8 or 9x4.7 prop, the Hellcat will even go straight up vertical out of your hand.

When you are ready to land, you can completely kill the throttle and glide her in or modulate it a little and fly her right to the ground. Landings are so easy to master but should you somehow get out of sorts when bringing the Hellcat back in at the end of a flight and cartwheel it, not to worry. The EPP is very resilient and the overall weight and mass of this type of air frame is so inconsequential that it usually does not suffer much damage on goofed up landings. Should the foam fracture or break due to excessive impact, gather all of the pieces if there is even more than the typical one or two, and glue it all back together. Most repairs are virtually undetectable thanks to the consistency of EPP foam.

Aerobatics/Special Flight Performance

With an AUW of 11.4 oz and total power of 125 to 140 watts, the Hellcat is definitely on the right side of the power curve. Since this air frame has both rudder and elevator, the sky is the limit when it comes to aerobatics. Thanks to the symmetrical airfoil, the Hellcat is just as at home inverted as right side up, with but an ever so slight push of down elevator necessary to hold the nose up. Though the rudder is relatively slender, the Hellcat will happily knife edge all the way across the field and then some. At wide open throttle, the Hellcat will really move out. Vertical is pretty much unlimited. Though I am definitely no 3D phenom, I am even able to hover the Hellcat for short durations. The prop is not really the best one for these 3D maneuvers though, and the control throws also limit the 3D-ability of the Hellcat. Depending on how hard you work the throttle, flights of between 4 and 8 minutes are possible when using this power system and the Thunder Power ProPower 45C 850mAh lipos. Even at continuous wide open throttle, the Super Tigre 400 motor does not cause the lipos to work hard enough to get anything more than warm. I regard this plane as the almost perfect "throw it in your trunk for a quick flight or two any time" plane. I have had mine out for flights at the beach too and it is a no-anxiety, loads-of-fun plane!

Is This For a Beginner?

From the standpoint that it can take a licking and keep on ticking, one of these Hacker Models WW2 EPP war birds could be a very good aerobatic trainer. I have seen folks fly an EPP airframe until it weighs almost double its original weight, due to all of the crashes and ensuing repairs with epoxy. Additionally, the total cost of the radio gear and electric power system for one of these EPP war birds is quite modest, making it attractive for those who may be on a strict RC budget. However, it does bear mentioning that the Hellcat for one has but a wee bit of dihedral and will pretty much stay in whatever orientation the pilot places it in, with little to no self-righting tendencies. You will need to fly it almost all of the time and cannot just take your hands off of the sticks when you get yourself into trouble. You will have to fly it back out of harmís way each and every time you get disoriented or in trouble.

Flight Video/Photo Gallery



I have been having a ton of fun with this profile war bird. It assembles and repairs quickly and easily. The EPP is super durable and the factory applied color scheme makes it look quite sharp when in the air. The GWS digital servos and Super Tigre brushless power system are very affordable and perfect for setting one of these versatile fun flyers up without emptying your wallet. The performance of the Super Tigre power system enables straight vertical launches and landings can be as easy as a plop right at your feet. Everything else in between can be as tame or as wild as you prefer!


  • Durable EPP air frame
  • Attractive pre-finished color scheme; choice of two different Hellcat schemes
  • Affordable Super Tigre electric power system
  • Solid performance from the modestly priced GWS digital servos


  • Aileron servo is pretty much permanently embedded in the wing and virtually inaccessible once glued in place
  • US distribution network not fully in place at the time of this review

So, you have read the review, you love the plane and you now want to click and buy one of your own? The next logical question would be "Where can I buy one?" Uh, well, that is a very good question and I am not sure I can really answer it at this juncture. Throughout the course of working this review up, I have spent some time trying to find an online e-tailer that lists this plane as available for purchase. The Hacker Models web site, listed above as the manufacturer, does have the product listed but attempting to actually purchase it directly from them turns up a goose egg. They do list a link to an "Online Store" but clicking on it in any one of the three languages offered only brings up a "Page Update in Progress" message. Hacker Models does list two different US distributors, RC Baron and World Toy Imports. But try as I might, I have been unable to find an actual listing for the Hellcat on either site. Both sites do list one or two different models of the World War II EPP fighter series however. And World Toy Imports claims that their next shipment from Hacker will include the complete lineup of Hacker Models EPP War Birds. I am hopeful that Karel Hacker will read this review and offer up another solution for US modelers who may wish to purchase one of these Hellcats. Private Messages sent to him during the course of this review all went unanswered.

Last edited by Angela H; Sep 20, 2010 at 04:18 PM..
Thread Tools
Sep 21, 2010, 03:31 PM
Registered User
Sherlock's Avatar
Barnes, where do you find time to build and fly all these models!!? I can barely repair a vapor wing with CA and get a 5min flight in durring my daughters nap. Nice review as always!
Sep 21, 2010, 08:21 PM
Bajora's Avatar
I cured myself of the need for sleep a while back. Sleep is a parasite that robs us of endless time that could be spent pursuing our hobby!

(just kidding!)

Latest blog entry: 2017 Reno Air Races
Sep 22, 2010, 06:18 PM
Registered User
Jon, great video, and please what is that fantastic music.!!! Ray
Sep 22, 2010, 06:48 PM
Bajora's Avatar
Ray...thank you. But I do not know the author of the music. It is a piece of royalty free music from a selection of files I have.
Latest blog entry: 2017 Reno Air Races
Sep 23, 2010, 09:28 AM
Balsa just crashes better
Cub Fan's Avatar
Great review- looks like a fun plane. Which other fighters are they doing?
I was wishing for a P-40

Cub Fan
Sep 23, 2010, 09:50 AM
Bajora's Avatar
Originally Posted by Cub Fan
Great review- looks like a fun plane. Which other fighters are they doing?
I was wishing for a P-40

Cub Fan
Thanks Cub Fan ... please check the third photo in the intro above for the other war birds available. Or click on the manufacturers link in the specifications section and browse them at Hacker Models site.
Latest blog entry: 2017 Reno Air Races
Sep 23, 2010, 03:33 PM
Registered User
jlcamp7's Avatar
This definitely looks like a nice little kit. This might be my first true build up of a plane. So far my planes have been BNF/PNP, but I want to build one up a little more and this looks like the perfect start. I think this will end up under the Christmas tree
Sep 23, 2010, 10:42 PM
badpilotto's Avatar

Another fantastic review! What a great flying plane.

Sep 29, 2010, 12:21 PM
The Flying Herb
rstein9's Avatar

Hacker makes good planes

but they are outrageously expensive for what they are.

you can buy a balsa plane for what they charge.
Sep 29, 2010, 10:25 PM
Registered User
Nice Review, like the plane too!
Oct 07, 2010, 06:01 PM
I tell her RC is cheap !
carguy1994ca's Avatar
Nice catch, great photography as always !

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