When Jimmie Wade met Mark Grohe at 2dogrc.com both were committed to designing airplanes. It did not take them long though to make changes to the previously hybridized, all-Depron Jimmie Wade Challenger offered by 2DogRC. Through those changes, they created the all 6mm EPP Predator. For both of them, EPP proved to be a material capable of meeting a single goal in their designs: design planes people enjoy so much they don’t want to put them down!
Given the flexibility of EPP, the design parameters had to successfully marry rigidity and flexibility and it had to do so in less than eight ounces, including the battery. One only has to pick the plane up to realize that while the AUW is less than eight ounces, the weight without the battery is 3.1 ounces including an excellent set of vinyl graphics. In a sense, you have a controllable flying leaf.
The bagged Predator is a complex kit with over 60 parts mostly consisting of carbon-fiber rods. Keep in mind that even though the Predator is an easy flying airplane good for intermediate to advanced pilots, the build is prescribed so you end up with an ETOC-capable biplane. It’s not a plane that goes together by itself, but if you take your time and follow the detailed color instructions provided on the enclosed CD, this plane rewards you with great flying characteristics.
If you are like me, you don’t start a project until you have everything in place. So let me recommend a few things that will make building the Predator successful. First, use the correct glue. Because EPP is so flexible, you need glue like Ultimate Glue to allow the EPP and the glue joint to flex together. Use sharp hobby knife blades like those offered by Excel and make sure your building surface is flat. As a final item, go to your local steel supply house and get four pieces of 1 inch by 1/2 inch flat steel in 12 inch lengths. These will really help hold the components flat and steady during the build.
The first portion of the project requires the installation of the vinyl graphics. These are very high quality and come with a self-sticking back. Even so, you should spray the back of the graphic with an adhesive spray before installing.
Hinging is done with fibered packing tape; use 1/2 inch or if you need to, split 3/4 inch down to size. It may seem odd that the tape strands run parallel to the hinge, but the holding power of the tape with EPP is excellent. All hinge bevels must be cut. Take your time and use a steel ruler to press against so your 45 degree bevel does not waiver. Ailerons, elevator and rudder are EPP.
One of the unique features of the Predator is that it uses EPP as the fuselage stiffener. The motor mount takes advantage of the fuselage stiffeners for support.
The bottom wing must be flat, square and perpendicular with the fuselage. Use the steel plates to hold the wing in place. Make sure your cabane struts are square and attach the upper wing. A series of carbon rods must be installed and keep the plane square throughout the process. The landing gear is optional, but I installed it and had no problem outdoors off a hard dirt surface.
Control horns for the ailerons extend the width of the ailerons for rigidity. Control linkages are carbon and require you to precut them and install only one Z-bend end. The final setup with all radio trims and servos centered requires you to heat-shrink the other Z-bend to the control horn. Use a soldering iron to shrink and then seal with CA.
Install the servos using hot glue. The Hitec HS-45HB Karbonite geared servos are an excellent choice. They are responsive, light and provide plenty of torque for 3D flying. They also include longer 3D servo arms and provide greater control surface movement. Dualsky’s 2815CA-24 brushless motor, Dualsky 6A SPAN>ESC and Hitec’s micro 05S receiver round out the needed components.
If you take your time and build accurately, you’ll end up with a superb-flying biplane. While in the air, there are no limits to what the Predator can achieve. It’s an excellent plane for stepping up your 3D and aerobatic skills and for learning new maneuvers. You can’t beat the durability. I recommend the setup provided by 2dog.com as it is well tested. In addition, the Hitec HS-45HB servos are a perfect complement. Keep the weight within the parameters, and I’ll bet this will become one of your favorite planes in your hangar.
IN THE AIR
If EPP has one really distinguishing characteristic it’s slow flight. The Predator can fly at nearly zero air speed into a light wind. Consider the wing loading at 3.4 ounces per square foot and you have a plane capable of full aerobatics, flight outdoors in light winds, indoors flight and one of the most durable planes I have ever flown. Much of the durability is attributed to the slow speed. I flat augured it into the ground and luckily caught a photograph at impact and the twist, contortion and flex was unbelievable. I picked it up and hand launched the Predator right back into the air.
Most of time, I fly outdoors, so I waited for a calm day to fly the Predator. I flew from both ground and hand launches and once airborne I knew I was flying something special. After trimming at 60% power, I flew both upright and inverted on the level, I put the Predator through a few maneuvers. One thing I noticed was it rolled well with the ailerons as a flat airfoil plane. The rolls were as tight on low rates as they were on high rates and only a slight amount of rudder was necessary to keep the nose straight forward. Loops were tight and knife edge flight was really easy. I was impressed that the rudder authority was not overly strong. When I needed the rudder it was certainly there, but I did not have to dial up the expo to reduce the input control. The hover was rock solid. I could drop into a hover and hold it very well and little or no wing rock was present.
I typically fly off of dirt or grass but one unique landing I figured out was I could hand launch and then while inverted, land easily upside down and save the landing gear. With just a very slight head wind, I could slow flight down enough to just set the Predator down on its back. So, to finish the maneuvering discussion, the harriers are beautiful. If you ever thought you needed weight in the tail to harrier or hover, here is a case against moving the weight back. In perfect balance, all the maneuvers are excellent.
As an indoor flyer, the Predator is excellent. You can easily keep it close, slow and under control. Any maneuver can be done in tight quarters and bumping a wall, basketball goal or whatever belongs in a gym is not going to end your flying.
CONTROL THROWS (
+ 30 degrees
with 30% expo (low)
+ 45 degrees or more with 40% expo (high)
+ 30 degrees with 30% expo (low)
+ 45 degrees or more with 40% expo (high)
+ 40 degrees with 30% expo (low)
+ 60 degrees max movement with 40% expo (high)
General Flight Performance
Stability: I think slow speed and stability are synonymous. Throughout the flight envelope, I thought the Predator wanted to react according to my inputs. It’s an excellent design with no limitations to what it can do with the right pilot in charge.
Tracking: Dead on. This is highly correlated with good design and building a true and square aircraft per the well-written instructions. The rudder was complementary to the flight not always critical as with some flat airfoil biplanes.
Aerobatics: Aerobatics are unlimited and can be accomplished in tight airspace. All maneuvers can be done indoors and only you will be the one limiting the aerobatic portfolio.
Glide and stall performance: Glide is an oddity basically because there is so little momentum. In no way is this statement a negative, as I always thought the Predator was following the prop and it does glide just fine. Stalls are so slight you don’t really even see them. Because of the wing loading and the weight stalls that initiate maneuvers are still there, but I just don’t think you recognize them the same way as heavier, larger planes. In fact, one could argue you feel them instead of see them.
All of these flight characteristics did not arrive arbitrarily. The fact that the Predator is a hybrid of previous Depron designs becomes quickly apparent. Whether doing rolling figure-8s, square knife- edge, Cuban-8s, or Humpty Bumps, the Predator is all about performing. It can turn, hang and rotate so quickly and precisely, you’ll be amazed.
I did notice after a few flights I had loosened a few carbon rods at the point where they join with the EPP in spite of using flexible glue. The fix though actually improves the hold as your EPP surface area increases for more holding power.
· All EPP
· Slow flight
Radio: HiTec Optic 6
Receiver: HiTec Micro 05S 5 channel
ESC: Dualsky 6A Brushless
Servos: HiTec HS-45HB Karbonite gear
Motor: Dualsky 2815CA-24 1450rpm
Battery: Dualsky 3S 450mAh 16c 11.1V
Prop: APC 9 x 6
Manufacturer: Alpha Foamies
Type: All EPP biplane
Wingspan: 29 in.
Wing area: 229 sq. in.
Length: 28 7/16
Weight: 7.1 oz. with battery
Wing loading: 3.4 oz./sq. ft.
Radio req’d: 4-channel programmable