RimFire Electric Power Setup

The Great Planes Combat Spitfire GP/EP ARF is "a sport warbird for everyone!" This is because it can be built up with either glow or electric power. When powered by a glow engine, it is AMA Event 750, Combat Class 2610 legal. This versatile MonoKote-covered, built-up balsa/ply ARF can be flown for sport-scale fun or compete in combat events. The flexible design of the Combat Spitfire also provides a choice of top or bottom aileron servo mounting and optional landing gear included in the almost-ready-to-fly kit.

2-stroke .25 cu in Glow Setup

Specifications:

• Wingspan Area: 272 in2 (17.5 dm2)
• Weight: 40-48 oz (1.13-1.36 kg)
• Wing Loading: 21-25 oz/ft2 (65-78 g/dm2)
• Length: 35.5 in (895 mm)
• Radio Required: 4-channel radio w/4-5 micro servos
• Glow Engine Required: 2-stroke .25 cu in (4 cc)
• Electric Motor Requirements: 1450kV out-runner brushless motor; 45A brushless ESC; 11.1V 3200 mAh LiPo battery

Key Features:

• High quality, built-up balsa/ply construction, covered in MonoKote film
• Includes mounting components for either glow or electric power
• AMA Event 750, Combat Class 2610 legal (when used with recommended glow set-up)
• One-piece wing with plywood wing joiner
• 2.25" (57.15mm) diameter white spinner included
• Pre-painted, fiberglass cowling
• Ready to fly in only 7-10 hours!

Great Planes includes a fiberglass cowl and lightweight, balsa/ply main structures covered in MonoKote? film. The Spitfire comes already covered with five colors of MonoKote film that represent a typical trim scheme of the World War II Allied fighter. Decals shown are included and die-cut for easy application. You can assemble this model for belly landings or with the fixed wire landing gear provided ? and mount your aileron servos and linkages on the top or bottom of the wing.

For my review, I'll be using a RimFire brushless electric power system. This is made from a GPMG4600 Great Planes Rimfire 35-30-1450 out-runner brushless motor, GPMM1840 Great Planes Silver Series 45A brushless ESC, and a GPMP0623 ElectriFly 3200mAh (20C) 3-cell LiPo battery.

The Spitfire requires four strong servos like the HCAM0111 Hobbico CS-12MG Servo with Hi-Speed and Metal Gears.

The assembly begins by attaching the ailerons to the wing halves with thin CA.

It is then time to decide what you plan to do with the Spitfire and how you plan to land it. There are servo bays in both the top and the bottom of the wings. If you plan to use the Spitfire for sport flying, you may want to install the optional landing gear and mount the servos on the bottom of the wing. If you plan to use the Spitfire for combat, you may choose to not install the optional landing gear and mount the servos on the top of the wing for smoother belly landings on grass. The assembly is the same for either mounting choice.

Since I decided that I would be belly landing my Spitfire on grass, I mounted the aileron servos on top of the wing. Simple painting of the servo and control horn can help hide the components in the air. Instead of using the Futaba (FUTM3910) 6" servo extensions, I choose a Hobbico (HCAM2751) Heavy-Duty Y-harness to lengthen the servo leads and join them to a single channel.

Motor Mounting:

To install the RimFire Brushless Outrunner motor, you build up the motor mount adapter from laser-cut parts. I used CA to hold it initially together and then reinforced the joints with epoxy. All the parts fit perfectly and the instructions in the manual are very detailed with plenty of photos. Note the built-in cooling system for the electric power version that allows air flow from the firewall out the bottom of the fuselage. The ESC is mounted to a plywood plate that sits right in the air flow.

Great Planes offers connector adapters to avoid people having to solder on the correct mating size. The item is GPMM3123 for a set of three adapters. As an alternative, I choose to solder the mating connectors that come with the RimFire motor onto the Silver Series ESC after first removing the existing connectors.

Tail Assembly:

The tail assembly was straight forward and the instructions had plenty of detail. If you follow the instructions, the split elevator halves assemble quite easily. Note that I routed the antenna wire through the fuselage and out the aft end. A little grey paint helps hide the control horns.

Battery Tray: The inside of the fuselage has a battery tray and a receiver tray glued in place for the electric power version. I used some ty-wraps to secure the receiver instead of the supplied rubber bands. The receiver is also held with servo tape on the bottom.

Servos: The servos mounted without issue and my only deviation from the stock setup was to eliminate the supplied quick links and use Z-bends where the control rods attach to the servo arm. As long as you center the servos electronically first, any offset needed to trim the elevator and rudder can be done on the transmitter. The Z-bends cannot slip in flight.

Cowl, Prop, and Spinner: The cowl was mounted using the masking tape alignment scheme in the manual. It provided excellent alignment. Some thin CA was added to the holes in the fuselage to help harden the wood.

The stock white spinner backplate and APC 9x6 Sport Propeller fit perfectly on the RimFire prop adapter without any drilling needed. I decided to try the glow prop as it fit without drilling and also added to the rugged look of the Combat Spitfire. If the glow prop proves not to be efficient on the RimFire electric motor, I'll replace it with an APC 9x6 e-prop. Note that I added an oval opening in the cowl bottom, per the manual, to help provide cooling air flow. A Dremel tool makes this an easy task.

Combat Spitfire Test Flight video.
CLICK HERE (5meg)

The Great Planes Combat Spitfire flew fantastic! It flies very fast, which was expected from the clean airframe. Most of the flights were spent around half throttle and we saw no bad tendencies. The winds were 10-15mph and the Spitfire was solid in flight. We performed loops and rolls at only half throttle. The warbird lands fast so it is important to bleed off much of the speed before belly landing on the grass. None of the power system components were hot after the flights which lasted about 12 to 15 minutes.

Spitfire Mock Combat Video
CLICK HERE (8meg)

I made a second video using a regulation streamer, and, our local combat expert, Matt Kirsch, puts the Great Planes Spitfire through some typical combat maneuvers. Matt is also an RCU Moderator.

Summary

The Great Planes Combat Spitfire GP/EP ARF truly is "a sport warbird for everyone!" Although it is only AMA Event 750, Combat Class 2610 legal when powered by a glow engine, the alternative electric power setup allows the Spitfire to be flown for sport-scale fun. My Great Planes Combat Spitfire was Ready-To-Fly at 39oz (or 2.4lbs) with the 10oz 3-cell ElectriFly 3200mAh (20C) LiPo pack. The powerful RimFire motor current draw was only 32 amps for an incredible 370 watts of power!

Although the Combat Spitfire balances perfectly with the suggested electric power system, it has been reported to be nose heavy with either an O.S. .25 or Thunder Tiger .25 glow engine installed. To properly balance the plane, either cut a little access area just in front of the tail feathers to mount the battery, or add 1.25oz lead weight to the tail. Moving the battery to the tail may be a better option as it doesn't add additional weight to the plane.

The Great Planes Combat Spitfire is solidly built from wood construction, not foam or plastic. The beautiful Monokote covering scheme, with pre-cut decals, provide true scale appearance without the challenges. It can handle a hard landing without breaking apart and simply flies as great as it looks. The Combat Spitfire is a winner!

Great Planes Model Distributors
P.O. Box 9021
Champaign, IL 61826-9021
Web: www.greatplanes.com

distributed exclusively by:
Great Planes Model Distributors
P.O. Box 9021; Champaign, IL 61826-9021
Telephone Contact: 217-398-8970
Web:www.electrifly.com

Hobbico ElectriStar Select
Distributed Exclusively by:
Great Planes Model Distributors
P.O. Box 9021
Champaign, IL 61826-9021
Available at your Local Hobby Shop
Web: www.hobbico.com

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