The Garrison Aerodrome Manx EPP S400 Flying Wing

Paul Bradley deviates from his traditional construction methods to try out this little EPP hotrod - with impressive results!

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Finished model

Specifications:
  • Type: EPP Foam Plank Type Flying Wing with a high "wooo weee" factor.
  • Wingspan: 36 inches
  • Wing Area: 192 Sq. in.
  • Wing section : Eppler 182
  • Length: 19 inches
  • Recommended Power: Speed 400 direct drive and a racing type prop (APC 5.5x4.5, Master Airscrew 5.5x4.5), and 8 600AE cells.. 
  • Weight:  the review model weighed 19 ounces ready to fly.
  • Controls: Throttle, Elevons
  • Construction: EPP foam, corrugated plastic, basswood, and balsa.
  • Suggested Price: $54.95 
  • Manufacturer: Garrison Aerodrome R/C Model Enterprises

Although I find myself getting "long in the tooth" modeling wise and tending to favor materials and techniques that come from my earlier years, I do like to see the great innovation that comes with the experimenting and introduction of new materials and methods. The world that has been opened by EPP foam based models is truly amazing. Mid-air collisions have always been events that were to be avoided. Thanks to EPP foam models, we can enjoy the excitement of full contact combat with little fear of our flying machines receiving much damage. EPP foam models have also made it possible to develop trainers that can withstand the punishment of inexperienced pilots without losing time or money to repairs. The designers of some of the EPP foam models have demonstrated some great "out of the box" thinking and we see the fruits of their imaginations doting the skies around our local flying fields. These truly are the good old days, and they just keep getting better.

Until recently, my personal involvement with EPP foam based models has been to admire them from afar. While appreciating their many qualities, I had not succumbed to their siren song to join their world. That is until the Dallas Electric Aircraft Fliers (DEAF) club held their annual fly-in. The month of October 2000 saw Darwin Garrison, the man behind Garrison Aerodrome, make the long trek from Ft. Wayne Indiana to the wilds of Texas to join in the fun at the DEAF fly-in. One of the neat items that emerged from his Garrison Aerodrome trailer was the Manx. It was a real head turner when airborne, but also caught my eye as I watched Darwin getting it ready for flight. His innovative use of the corrugations in the bottom keel as a hatch hold down mechanism said to me that this designer is a real thinker. As a result, when the opportunity arose to actually build and fly a Manx, I could no longer resist the siren song. As was the case with my first experience in the world of ARF models (Dymond L-19 Bird Dog), I get to share with you my first experience with an EPP foam model, the Garrison Aerodrome Manx.

Kit Contents

Opening the Manx kit box was the first of a number of first time experiences for me with this model. Rather than being greeted with stacks of balsa wood containing many parts, the box contained a couple of wing shaped blocks of foam, a nicely shaped piece of foam that looked to be a fuselage, and several plastic bags of "stuff". In one of the bags was some good old fashioned wood for the elevons, spar, and wing sub-trailing edges. In another bag was a nice assortment of hardware. This included a laser cut plywood motor mount, the necessary control linkage hardware, and a genuine plastic spoon. All kidding aside, it is a common practice to cut a plastic spoon in half to form an air scoop. Darwin made sure you would not have to go hunting for one when the time came for making the air scoop, so he kindly included one in the hardware bag. The third parts bag contained several pre-cut pieces of corrugated plastic. These represented a bottom keel for the fuselage and the vertical fin. Just in case, Darwin also threw in an extra piece of corrugated plastic and a block of EPP foam. I guess these were for repairs, but based on my stress testing of the model (see the flying section) you are not likely to use the extra material.

Kit_contents.jpg (26021 bytes)

Manual

Kit Contents. Assembly Manual.

In addition to the core materials you will need to build the model, the kit also includes a very comprehensive building manual. Darwin is to be commended for the completeness of the assembly manual. It is done in check box style and covers each building step very thoroughly. I should note that in the very beginning of the manual a table is presented that outlines the various materials you will need to supply in order to complete the model. This includes some 2" and 1" (or 3/4") filament strapping tape, and an assortment of adhesives. The adhesives include polyurethane glue, contact cement, and a spray adhesive like 3M-77. Since I had not previously built an EPP foam model, this meant that I had to make a trip to the local building supply store to get the needed materials. Darwin cautions the builder to follow his recommendations for adhesives, and based on my experience with the model I would certainly concur. It becomes apparent very quickly that he has done this a few times, and is sharing his experience with the builder to help insure a successful result.

Construction

Wing

The assembly manual begins the building process with the wing. For a flying-wing type model I guess this makes perfect sense. Contained in the two wing-shaped blocks of EPP foam are the model’s wings. Each wing half is delivered still somewhat attached to the bottom core bed. This is an artifact of the hot wire cutting process that leaves some EPP foam slag still attached to the wing panel.  As a result, the first step is to separate the wing panel from its base and clean up the slag. This is certainly an easy process, but it does require a bit of care to make sure all the slag is removed and that the panels are not damaged.

Wing slag

Wing spar slot

Wing assembly begins by separating the wing halves from the beds and removing the EPP slag. After clean up of the slag and light sanding, the wing halves are joined with contact cement. Note the clean notch for the bass wood spar.

Once the slag has been removed, you check the groove for the spar to be sure it is clean. For my model I found the groove to be very cleanly cut with no clean up needed. At this point we join the wing halves with contact cement and get ready to glue in the bass wood spar. Polyurethane glue is used here and this was my first experience with that adhesive type. Before applying any glue you first wipe the parts with a damp cloth. Once that is done the glue is applied to the groove in the wing and spread to give a thin even coating. The spar is then placed in the groove and the entire assembly is placed on the core beds and weighted down. The polyurethane glue takes awhile to cure completely... like overnight. Polyurethane glue is really neat stuff. As it sets it expands a bit and forms some bubbles. The expansion forces the glue into the foam cell structure and makes a super bond. It is also easy to sand, so clean up of any excess is pretty easy.

Wing and spar

Wing and sub trailing edge

The 1/4" square bass wood spar is glued in place using Polyurethane glue. The glue makes an excellent bond and is very strong. Next the bass wood sub trailing edge strips are glued in place and sanded to the proper profile.

After the main spar is in place and trimmed, you add the bass wood sub trailing edges. Darwin suggests using 5 minute epoxy for this step. I discovered I had run out of 5 minute epoxy so I decided to deviate just a bit and used Pica Glue-it. This worked fine, but that is the only place I did venture out on my own and use an adhesive other than the one recommended for the job. Once the glue has set, the sub trailing edges do require some sanding to get them to blend to the wings' profile.

The last bit of wood working for this model comes next. The elevons are made up from supplied 1" triangular balsa stock. The portion of each elevon that will be fixed at the center section is cut away from the stock and glued in place. Each elevon is then taped in place along the bottom of the wing using masking tape. The supplied stock is thicker at the hinge line than the wing profile at that point, so some shaping is needed. I used a razor plane to remove the major portion of the balsa and then completed the shaping process with a long sanding block. During the shaping process care must be taken not to remove material from the basic wing panel. Masking tape can be used to protect the EPP foam if you like.

Wing and elevons

Wing ready to tape

The elevons are made from supplied 1 inch tapered stock. A bit of sanding/shaping is required to reduce their thickness to that of the wing trailing edge. The wing is covered with 2" strapping tape on the top and bottom.

Once the wood working is complete, you have the "hard" part done. The remainder of the wing assembly process involves applying filament strapping tape and the chosen covering material. The wing gets a total layer of 2" wide strapping tape on the top and bottom followed by a second layer just over the spar top and bottom. The second layer of strapping tape uses the narrower tape that can be either 1" or 3/4" tape. Prior to each application of tape, the wing receives a coat of 3M-77 spray adhesive. I think I have to refine my technique for applying the spray adhesive. My finished Manx ended up a bit over weight, and I think some of the added weight came from using too much spray adhesive. You should apply light even coats of the spray adhesive.

Wing covered with strapping tape

Covered wing

All taped and ready to cover. A second layer of tape is applied over the spars on the top and bottom. Covered wing with the elevons installed. Covering is white UltraCote.

With all the strapping tape in place on the wing, you are ready to apply the finish covering. Darwin notes that you can use either a conventional covering film (he recommends UltraCote), or colored packing tape. I chose to use UltraCote. I also decided to use white as the base color because I can see it well against the sky. When finished covering the wing and the elevons, you then attach the elevons to the wing. Darwin also covers alternatives for this step in the process. He suggests the use of either hinge tape, or a hinge made from the covering material. I used the latter alternative for my hinges and made "skin" type hinges from strips of the UltraCote.

Fuselage

With the wing completed, we are well along toward finishing the Manx. Since the vertical fin comes pre-cut from the corrugated plastic and there is no horizontal stabilizer, the only thing left for us to assemble is the fuselage. This part of the building process begins with the corrugated plastic bottom keel. The keel comes already cut to the basic shape. All we need to do is cut out the cooling air exit hole and the battery hatch. The lines to guide the cuts are already applied to the parts, so it is a pretty easy job. The only trick we need to watch out for is cutting the corrugated plastic to form the hinge for the battery hatch. This is clearly explained in the manual, so you should have no problem completing this step. Darwin demonstrates some of his "out of the box" thinking with this component. Once the battery hatch is cut and the hinge is formed, we see the clever way he retains the hatch. He simply runs a length of plastic rod through one of the corrugation "tubes" that engages the hatch. The rod has a screw and washer inserted in one end to act as a stop and removal grip. The battery pack is under a bit of compression when the hatch is closed, so there is plenty of force on the retaining rod to keep it from moving forward until you want to open the hatch. A very simple and elegant design.

Fuselage keel

Fuselage keel installed

Servo wells

The fuselage keel is made from corrugated plastic. All you have to do is cut the hatch free. Clever use of the corrugations is made to lock the hatch. The corrugated plastic bottom keel and plywood motor mount are attached with contact cement. The servos are mounted in the fuselage sides. Wells are cut into the foam for the servos.

Once the bottom keel has been prepared, the EPP foam fuselage gets a little work. It is necessary to extend the motor tunnel into the battery compartment. This makes it possible to install the motor from behind the motor mount, and also establishes a path for cooling air to pass over the speed control and battery pack. The manual details the process that basically involves punching through the foam and then final shaping with sand paper on a dowel. When the motor tunnel work is complete, the bottom keel is glued to the EPP foam fuselage using contact cement. This makes a very strong joint. After the keel is in place the laser cut plywood motor mount is installed. Contact cement is used for this joint as well. Following installation of the motor mount, two wells are cut into the foam where the servos will be installed. Darwin uses hot melt glue to retain the servos in the wells. While this works perfectly fine, I’m just not comfortable gluing in servos. Call me old fashioned, but I do prefer to retain servos with screws. As a result, I did deviate just a bit from the planned construction and added plywood servo mounts to each well. The mounts were made from 1/16" plywood and applied to the EPP fuselage sides with contact cement (I did learn something by this point in the process).

Fuselage shaping

Servo mounts

Covered fuselage

Square edges of the fuselage are rounded off in preparation for application of strapping tape. I decided to add plywood servo mounts rather than glue in the servos. The mounts are attached with contact cement. After taping the fuselage it is covered and the fin is added. Like the wing, white UltraCote was used for the covering

All that is left for us to do is tape the fuselage and add the vertical fin. Prior to starting the fuselage taping process, Darwin suggests rounding off some of the square edges if you want a smoother look. You can’t do anything along the fuselage bottom due to the corrugated plastic keel, so I ended up rounding off the top of the nose and the rear fuselage. Doing the rear of the fuselage was probably unnecessary, and I’m sure did little for the aerodynamics of the model. Strapping tape is applied to the fuselage using the same technique as the wing. A coat of 3M-77 spray adhesive is applied followed by the strapping tape. The taping sequence is clearly covered in the assembly manual. Like the wing, once the taping process is finished you apply your chosen finish covering material. Also like the wing, I used white UltraCote for this step.

The fuselage is joined to the wing using contact cement with a bead of Goop or hot melt glue running around the perimeter of the wing saddle area. This makes a surprisingly strong joint. One at least that I could not separate in all my stress testing ... otherwise known as flying.

Covering and Finish

Finished model

Finished model - bottom

Trim is Neon Red self adhesive MonoKote.  Bottom trim pattern was set up to make it easy to tell the difference from top and bottom while in flight. 

By the time we reach this point in the project, there really isn’t much to do. We have already applied the basic covering to the wing and fuselage/fin assemblies. This leaves only the trim color(s) if you want to dress up this tailless cat just a bit. To help visibility, I decided on using self adhesive MonoKote Neon Red for the trim color. This made adding trim pretty easy. Also since my supply of UltraCote was limited to my roll of white, I needed something that could be used on the bottom of the wing that would give a good reference for the models orientation. The final trim layout also included adding a contrasting black stripe between the Neon Red and the basic white. For the AMA number and model name, I cut these features from black MonoKote that was 1/16" larger. The black was applied first to the model followed by the self adhesive Neon Red. The fuselage trim color separation stripe was cut from black MonoKote using a Top Flite stripe cutter.

Equipment Installation

Equipment selection for the Manx is pretty straight forward. It calls for a direct drive 6v Speed 400 as the motive force. That is coupled to a Graupner precision speed prop spinner assembly. For props Darwin recommends a Master Airscrew 5.5x4.5 or an APC 5.5x4.5. I strongly recommend you follow this recommendation. I chose to use the Graupner 5x5 that came with the motor package I had purchased. The smaller diameter and increased pitch of that prop proved to be problematic on the first flights.

For a speed control, there are a number of good choices. You want one that can run at a sustained current draw of 10 to 13 amps. Thanks to some great good fortune during the door prize drawing held at the 2000 Mid-America event, I came into the possession of a New Creations M-30 speed control. This unit fit in the available space with no problem and had the necessary sustained current rating. For servos I chose to use two FMA S-80 units. Again, there are certainly a number of choices that could be made, all of which would work very will with the Manx. Finally, for a receiver I used the venerable Hitec 555. The manual uses that receiver as the example installation, and it does indeed fit the provided space very well. Overall, I found installing the equipment in the Manx to be painless. Just a matter of punching a hole here or there to route servo wires, and slicing several servo lead channels. To keep the model really clean, I also used a Deans antenna. I mounted it between the wing and fuselage when those two components were mated. About 1" of the antenna extended into the root of the fin. This worked great with no range problems.

Equipment installation

The receiver fits at the back of the battery compartment. The ESC fits in the tunnel used to install the motor and to receive cooling air from the nose scoop. A Deans antenna was installed between the wing and fuselage and extends into the base of the fin.

I probably shouldn’t do this but I feel the need to tell on myself about one aspect of the equipment set-up. Not only was the Manx my first EPP foam model, but it was also my first using elevons for control. Certainly no big deal I told myself when the time came to set up the model in my Prism 7X transmitter. It has a built-in setting for elevon mixing. So the process began. After verifying the neutral points for each servo, I started checking the control throws. Of course the functions were reversed. The elevator input produced aileron action and visa versa. Ok, reverse the servos in the transmitter. This solved the control input problem, but no combination would produce the correct elevator and aileron directions. If I set the elevator direction then the ailerons were reversed. I’m sure many of you are laughing at this point at my dilemma. The solution, of course, was very simple but sometimes the obvious takes me awhile to fall over. The answer was simply to reverse the channels the servos were plugged into. I mention this just in case someone reading this may also be setting up elevons for the first time.

When all was ready for flight, I placed the completed model along with a flight battery pack on my triple beam scale to see where the ready to fly weight ended up. I was pretty disappointed to see that I came out 1.5 ounces heavier (19 ounces total) than the weight suggested on the Garrison Aerodrome web site (17.5 ounces total). My guess is that the speed control may be a bit heavier than the one used by Darwin in his prototype, and my lack of experience with the application of 3M-77 spray adhesive took it's toll.

Flying

While I certainly don’t view myself as an expert pilot, I have logged a number of hours at the controls of Speed 400 powered model aircraft. That being said, the Manx demonstrated that I had plenty of room for more learning opportunities. This model reacts if you just think about doing something. It also does it in a hurry. In other words, this cat has a bite, but as I quickly learned the bite is very gentle in terms of causing any harm. With that little teaser, let me take you through my flying experiences with this hot little number.

First and foremost, Darwin Garrison does a great job of describing how to set up the Manx in the manual. He specifies the requisite control throws, and also gives excellent guidance on the use of dual rates and exponential if your transmitter has those functions. Like everything else in his well written manual, PAY ATTENTION!!! It does not take much control input to cause the Manx to change direction or attitude. Of course, when properly tamed, that makes for one fun and exciting flying machine.

Getting ready for first flight

Model diving at a distance

Fly by
All smiles getting ready for the fist flight. Coming out of a loop. A bit far off for the camera. A closer fly-by shot. Speed of the model makes it hard to keep every thing in focus.
These photos by Ralph Bradley

The review Manx was set-up per the manual for the first flight. A check of full power current draw with my Astro Wattmeter indicated all was well. After a successful range check we were ready to go. My able assistant and brother Ralph had the honors of being the model launcher. The first launch ended quickly with the model simply doing a belly flop in the weeds. Remember, I was not using the recommended prop, but one with less diameter and more pitch. It just did not want to get up any speed. We tried again with a little more gusto on the launch. That attempt ended with the model being thrown into the dirt. This was my first look at the incredible toughness of the Manx. Other than a bit of dirt on the nose and a broken prop, it did not have a scratch.

The broken prop at first seemed like a show stopper for the day. I did not have the proper prop on hand and started looking through my field box. Low and behold I found I had a Robbe 6x3.5 folder with me. What the heck I thought. So on went the prop. The third flight attempt saw a transformed model. It just pulled right out of Ralph’s hand and off it climbed. Even with the reduced pitch from that recommended, the model got down range in a hurry. As suggested would happen by Darwin, I had to apply a little down trim. His recommended initial elevon reflex setting is to help insure the model will have a positive climb on the first launch. Now we could get down to business. I gently fed in some aileron to head her back toward me. In a heart beat she had done a 180 degree turn. Ok ... I thought this model has some spunk. A few circuits around the field and then it was time to see what she could do. Rolls are very quick. In fact, be real gentle on the controls or rolls will be what you get when you want to just turn the model. Loops are large and again do not require much control input. I found myself getting comfortable very quickly with this model. Duration was just over three minutes. I had a real problem pulling the throttle stick back. Speed I find is addictive. I'm sure that with the recommend props, the Manx would be even more spirited.

Several more flights found me getting a bit more bold. These flights also taught me to respect the control authority of this model. While doing loops I found that aileron input would result in some pretty wild maneuvers. When attempting to correct for a loop that was drifting off line, I applied a little correcting aileron. The Manx snapped off a couple of rolls and who knows what else. I was so far behind the model that I did not know which end was up. Fortunately, I had lots of altitude, so I was able to somehow get her back to straight and level flight. I was beginning to feel real humble about this time. Please don’t get me wrong. The Manx is not hard to fly. It is a very spirited model that will really respond to your commands. Just work up to the wild stuff gradually. Oh yea, when it comes time to land the Manx she is a real pussy cat. Allow a nice long approach because the glide is long and flat. As she bleeds off speed I found you could ease the stick back gradually and she would settle in very nicely.

Post crash minimal damage

The results of a very hard straight in crash from altitude. Other than a broken prop and some cosmetic wrinkles in the fuselage, there was no damage. This is one very tough bird.

As you might guess there is more to this story. If you read the construction notes, you may remember that I hinted at doing some stress testing of this model. Somehow stress testing sounds a lot better than crashing. Somewhere around the eighth flight of the day ( I was having a lot of fun) I decided to really fine tune my aerobatic touch with the Manx. Still feeling the need for enough altitude for several mistakes, I let her climb to a comfortable altitude. A few rolls and then I wanted to get that perfectly tracking loop. I guess I was getting tired, and I kind of misjudged where I started the loop. The wind had come up at my back (did not bother the model) so I was flying toward myself. I was closer in than I should have been and at the top of the loop I decided to again feed in a bit of aileron correction. The model started a roll and before I knew it I lost orientation. The model got behind me which only made matters worse. Before I knew it, she was heading straight down from about 150 feet. The Manx goes down hill real fast! All I heard was a loud thump. You know that sickening sound. I walked over to the crash site expecting to see a lot of debris. The nose was buried in the ground for about 3 inches. I had a real epiphany at this point regarding EPP foam models. The only damage was a broken prop hub, and several wrinkles in the fuselage. The plywood motor mount was unhurt, no damage to the servos, or any other equipment. Simply amazing.

Recommendation

If you have ever fancied flying one of the Speed 400 pylon models or hotliners but felt your flying skills aren't up to the task, I think the Manx would be a great trainer. It is plenty fast, very responsive to the controls, and incredibly forgiving to pilot mistakes. You will definitely hone your piloting skills flying the Manx while at the same time not having to fear the consequences of making a mistake. And talk about pure fun. I can’t imagine that you would become tired or bored with this model. It is just too spirited to not continually give you a rush each time you send her aloft. I never knew foam could feel so good. Darwin Garrison has given us a real keeper.

If you have any questions or comment, feel free to contact me BradleyP(at)ix.netcom.com

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