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This item is discontinued. GREAT PLANES FOKKER DR-1 ARF
SPECIFICATIONS RCM PROTOTYPE SUMMARY
Introduction: My favorite era of aircraft is from World War I. Many brave men climbed into these frail wood and fabric machines knowing that they would not return. One of the reasons for this phenomenon was attributable to the flying skills of Manfred von Richtofen (the "Red Baron"). The war's leading ace excelled in each of the aircraft he used, the last of which (before being shot down himself) was the Fokker Dr.I. Richtofen regularly flew at least four different triplanes and while all of them had a dark red base color, they each had slightly different trim schemes. The aircraft Great Planes chose to model was the one he would use when visiting other wings under his command or when he was visiting the Fokker factory. The full-scale Dr.I had an upper wingspan of 23' 7". The model boasts of a 60-1/4" span (making it slightly smaller than quarter-scale but IMAA-legal).
The Kit: The kit box for this ARF model measures 56" long, 14" wide, and 10" tall. A compartment measuring 9-1/2" x 19-1/2" secures the aft end of the fuselage in place and holds assorted parts (engine mount, one-piece fiberglass cowl, wheels, hardware, landing gear, etc.). Each major component is individually packaged in a clear plastic bag. All three wings come fully assembled; the modeler does not have to glue wing halves together. Everything was easy to identify. When the kit arrived at RCM, the fuselage had some crushing damage incurred during the shipping process but a call to the Great Planes Product Support area got a replacement within a few days. (Pretty awesome customer service!) Otherwise, there were no warps, waves, twists or any other significant problems. There are no plans because it's an ARF kit and none are needed. The instruction manual is 35-pages long; it's typical Great Planes workmanship easy to read, well laid out, and the picture quality is above average. It has a number of hints, notes, and cautions annotated throughout to make the building, finishing, and flying process easy.
Construction: The manufacturer projects building time to be about 15 hours; it took me over 20 hours to be ready for flight-testing. The materials used throughout construction seemed to be above average quality. Construction begins with the attachment of the one-piece painted wire landing gear to the fuselage. Because the muffler vents just under the firewall, care must be taken to adequately fuelproof the grooves into which the landing gear is attached. The instruction manual does a good job of bringing this to the attention of the modeler. Furthermore, in anticipation of the stress associated with taking off from and landing on grass runways, it's noteworthy that eight nylon straps are used to secure the gear to the fuselage. Fore and aft landing gear covers are later added for decorative purposes. A non-steerable one-piece plywood tail skid is added to the bottom aft end of the fuselage. The fuselage construction utilizes a lite plywood frame with seven formers. The top and front two-thirds of the fuselage sides are sheeted with 3/32" balsa. The remainder is open frame construction. The plywood firewall has approximately 5° of right thrust and is coated with fuelproofing.
The middle and bottom wings are attached to the fuselage with two dowels protruding through the leading edge and two nylon screws through the trailing edge. The top wing is screwed to the cabane struts and outboard wing struts. The cabane struts are all-metal and add strength and rigidity to the assembly. The outboard wing struts do not pass through the middle wing. Instead, each strut is composed of top and bottom pieces of clear-coated 1/4" lite plywood. Screws pass through holes in the top and bottom of each strut section into metal "L" brackets attached to the wing. One end of the "L" bracket is threaded to accept the 4-40 screw that passes through the strut. Wing construction consists of capstripped 3/32" balsa ribs with 2" leading and 1" trailing edge sheeting. The center sections are also sheeted. Note the scallop design on the trailing edge of the wings. The one-piece rudder uses a 1/2" plywood open frame construction and has an airfoil shape created by balsa ribs. As on the full-scale aircraft, the entire rudder moves; there is no fixed fin. The stabilizer/elevators also have an open frame construction. Great Planes 6-minute epoxy was used to attach the stabilizer to the fuselage. A Great Planes C.G. Machine revealed that the prototype balanced tail heavy and this was easily corrected with 6 oz. of weight to the firewall and a Higley heavy hub. Covering: The model comes precovered in dark red Top Flite MonoKote trimmed with white fields on the top and bottom wings (and fuselage sides) for the black Maltese crosses. The two-piece Maltese cross designs have already been attached to the surfaces at the factory. Stick-on decals are limited to the instrument panel and some markings on the sides of the fuselage. The rudder is covered in white MonoKote and the cowl seems to be finished with white LusterKote. The covering job was exceptional. A pilot figure is not included in the kit although the cockpit coaming, two well-detailed machine guns, and 6" vintage sponge wheels are. A 1/5th Williams Bros. pilot bust fits nicely and some 1/2" ribbon works well as a scarf. (WWI pilots used the scarf to keep warm and to wipe excess castor off their windshield and face.) The interior cockpit area was coated with black Coverite paint. For added realism, a 1/16" wire step is installed to the side of the fuselage.
Engine: I chose to power the test model with the maximum engine size suggested and opted for a reliable O.S. Max 70 4-stroke engine with its stock muffler swinging a Zinger 13 x 8 wooden propeller. The 13" prop left plenty of ground clearance. The engine is mounted inverted (but not at 90-degrees) so that the muffler passes under the center bottom of the nose section. An engine mounting template in the instruction manual ensures proper alignment. Hollow plastic dummy engine cylinders (provided in the kit and attached to the interior bottom of the cowl) give the appearance of the rotary engine that powered the full-scale aircraft. Included in the kit was a two-piece Great Planes adjustable engine mount and all the hardware (screws, nuts, washers, etc.) needed to attach the engine mount to the firewall and the engine to the mount. A 14-ounce fuel tank was also included. The one-piece fiberglass cowl is attached to the firewall with four screws. I used a scrap piece of wire as a needle valve extension that passed through the cowl and to minimize vibration damage, I attached a piece of scrap to one of the cowl blocks and drilled a small hole for the needle valve extension.
Radio: Radio installation is surprisingly simple. Five servos are needed (two for the ailerons and one each for the rudder, elevator, and throttle). The aileron servos are attached to access panels on the bottom of the top wing; the pushrods pass through an opening in the panel. A "Y" harness and two 12" servo extensions are needed to connect the two aileron servos. Another 6" servo extension (connected to the receiver) passes through the top of the fuselage and is attached (with two strips of clear tape) to the interior of the cabane strut to complete the connection with the top wing. The switch and charging jack were attached to the fuselage side just under the middle wing. I should point out that the instruction manual also offers an alternative installation method for the aileron connection. In lieu of cutting a hole into the top of the fuselage, a female servo receptacle could be added. This method would provide the modeler with an easier means of removing the top wing during transit. If you are unable to transport the Dr.I fully assembled, plan on about 30 minutes set-up time at the field. There is plenty of room in the fuselage within which to work. Plywood servo trays and nylon pushrod tubing are pre-installed. Threaded metal pushrods pass through the tubing to each elevator half and the rudder. The elevator pushrods are joined at the servo end and the instruction manual suggests that they be held together with two wheel collars. I was not comfortable with this arrangement (because of engine vibration) and chose to silver solder this connection instead. Before completing this step, make certain that the elevator halves are properly aligned. My choice of radio was the Airtronics RD6000 Super system with an 8-channel model memory; Airtronics 322 servos were used throughout.
Flying: The instruction manual offers some good coaching tips on the Dr.I's flying personality. Pay lots of attention to this. Dr.Is generally fly well once they're airborne but are difficult during take-off and landing because its stubby and tall shape results in an abnormally high Center of Gravity. Flying from a grass runway is highly desirable because ground loops are always a concern. Fortunately, the engineers at Great Planes figured this out and the frame of the rudder is plywood that can withstand this type of shock better than balsa. Because of the (scale) non-steerable tail skid, ground handling was only fair. For take-offs, I pointed the model into the wind, gradually increased the throttle to about 1/2, held in just a little right rudder to compensate for engine torque, and applied some gentle up elevator after I picked up speed; it does not require much runway for take-off. The tail comes up as soon as throttle is applied. The climb rate should be at about 30-degrees. In order to achieve straight and level flight, I needed to add three clicks of down elevator and four clicks of left aileron. There's nothing quite like watching a triplane in flight (and adding to that is the realistic sound of a 4-stroke engine). The amount of high rate and low rate throw each flying surface needs is clearly specified in the instruction manual. I followed this exactly with excellent flight results.
The O.S. Max 70 Surpass provides solid scale-like power for this model. The Dr.I flies well when ailerons and rudder are coordinated but is quite manageable using just ailerons for turns. Loops with a 50' diameter were easily accomplished although at 75' it struggled at the top of the loop. Rolls had a "barrel" shape to them. Knife-edge flight required a fair amount of effort but was achievable. Spins were not snappy. The Dr.I was solid during inverted flight, requiring just a little down elevator. I also tried the Dr.I with a pumped O.S. Max FS-91 II Surpass swinging a 15 x 6 prop. Although it flew considerably faster than scale speed, there was a quantum leap in aerobatic performance. If you choose to go with a larger engine, don't forget to throttle back lest you encounter flutter. Landings are "interesting." The test model settled nicely on 1/4 throttle; the controls remained fairly responsive. Be sure to bring it in with the nose as level to the runway as possible and with sufficient speed. Once the main gear touches ground, it's important to gradually feed in up elevator to keep the tail down. Conclusion: Great Planes deserves the reputation it has earned for customer service, ingenuity, and the quality line of upscale ARF kits it offers. I don't know what these people are going to introduce to the market next, but it's certainly guaranteed to be an eye-catcher. The Dr.I earned many "oohs" and "ahs" when I brought it to my club meeting for "show and tell," but even more vocal enthusiasm by the people who've seen it fly. Unfortunately, the photos of this model in hobby ads don't do it justice. It's a much more handsome model than the photos portray. Check it out at your hobby dealer. If you like WWI aircraft, this one deserves strong consideration. Flight Photos by Joe Oszmanski. Reprinted with permission.November, 2002 R/C Modeler Magazine Editor: Patricia Crews
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