by Jack J. Joseph

Extra 300S photo


Name: EXTRA 300S 60
Aircraft Type: Sport/Scale
Mfg. By: Great Planes Model Mfg. Co., P.O. Box 9021, Champaign, Illinois 61826-9021
Mfg. Sug. Retail Price: $219.99
Available From: Retail Outlets
Wingspan: 64 in.
Wing Chord: 11.5 in. (avg.)
Total Wing Area: 744 sq. in.
Fuselage Length: 54.25 in.
Stabilizer Span: 24.5 in.
Total Stab Area: 98 sq. in.
Mfg. Rec. Engine Range: 0.61-0.91 2-stroke, 0.91-1.20 4-stroke
Rec. Fuel Tank Size: 12 oz.
Rec. No. of Channels: 4
Rec. Control Functions: Rudder, Elevator, Throttle, Aileron

Basic Materials Used In Construction:

Fuselage: Lite Ply & Balsa
Wing: Basswood & Balsa
Tail Surfaces: Balsa
Building Instructions on Plan Sheets: No
Instruction Manual: Yes (46 pages)
Construction Photos: Yes


Radio Used: Futaba 6XA w/5 Servos
Engine Make & Disp.: O.S. .61FX
Tank Size Used: 12 oz.
Weight, Ready to Fly: 124 oz. (7 lbs., 12 oz.)
Wing Loading: 24 oz./sq. ft.


Die-cutting, instruction manual was easy to understand and follow, the model went together very easily, and flight performance.

Nothing to dislike.

The giant planes flown by IMAC competitors aren't my cup of tea. I couldn't get a wing in my car, let alone the fuselage, so when the Great Planes Model Manufacturing Company announced their new 60 size Extra 300S in October, 1998, it seemed an answer to my dilemma. I ordered one.

The kit came in a brightly illustrated box that measured 30" x 10.5" x 6". The small metal and some wood parts were bagged and the canopy was wrapped in tissue. I removed all of the items and, to make each part easy to identify, I used a thin point pen to ink the stamped parts numbers on each of the sheets.

The rolled plans were on two 36" x 46" sheets and a 48-page instruction manual accompanied the plans. The manual contained 183 pictures and 18 sketches, plus a list of required accessories and tools, and a discussion on engine selection. The center section of the manual was an 8.5" x 17" reproduction of the large plans which was extremely helpful, as it kept me from having to unroll the plans to identify a part and its location while I went over the instruction manual and, later, during assembly when the parts being assembled covered the plans.

The quality of the parts was first class. The die-cut balsa and plywood parts were easily removed from the sheets and only required a fast touch of sandpaper to remove any burrs.

I used a variety of adhesives: Pacer Zap and Slo-Zap, Great Planes Pro Wood Glue and Frank's Hobby House 5 and 30-minute epoxy. All of the nuts and bolts were secured with Loctite 242 Thread Locker.

The instructions in the manual were easy to follow; just do as instructed, check off each step as it is completed, and "voila" you have a great model.

The tail feathers were framed with 5/16" balsa. The stabilizer and fin were then sheeted with 1/16" balsa. The elevators and rudder were open frames.

Since hardwood wing spars are seldom straight as an arrow, I was pleased to find instructions on how to install the upper and lower spars so any warps would counteract each other and result in a straight beam.

The wing was standard built-up construction. Although the 1/16" balsa sheeting surprised me since most planes of this size I had encountered used 3/32" or 1/8". No doubt this is a way to save weight. When you build this plane, always pick up the wing at the center section or you will have a bit of patching to do, as the 1/16" sheeting is fragile.

I used a servo for each aileron and, to keep the wires from chafing on the ribs, I rolled some tubes out of typing paper, coated them with FolkArt's Clearcote Hi-Shine Glaze to make them stiff and tough and tacked them to the ribs with CA. When I installed the servos, I ran the wires through the tubes.

The fuselage went together without a hitch. The three 1/8" ply firewall pieces were epoxied together and clamped between two hardwood boards to cancel out any warp. The entire fuselage was assembled and held together by clamps and rubber bands before one drop of adhesive was applied. I had a problem bending the fuselage sides around the forward formers. The instruction said "wet" the ply. "Wet" didn't work, but "soaking," strong clamps and 30-minute epoxy did.

When I fitted the wing to the fuselage, there was a large gap between the wing roots and the fuselage. The manual said nothing about filling the gap so I e-mailed Great Planes and was instructed to "...use balsa strips or sticks to fill the majority of the gap and smooth out with filler as needed." Actually, I used Hobbico's HobbyLite filler and with minimum work produced a tight fit.

I was surprised when I got to the belly pan instructions. I'm used to plastic pans, but you won't find such a thing on this plane. The Extra's pan is a ply skeleton covered with MonoKote.

After giving the stab its final sanding, I mounted the wing on the fuse and used Robart's Model Incidence Meter to set the incidence of the stabilizer. It was then attached with 30-minute epoxy.

The skeleton completed, it was time to begin the finishing process so I got out the sandpaper and went to work. I started carefully with 180 grit and ended with 210.

I assembled the cowl and wheel pants and used Bondo Glazing & Spot Putty #907 to fill the seams. After sanding them smooth, they were sprayed with LustreKote primer, smoothed down with 400 grit paper, and painted with LustreKote paint. The paint matched the MonoKote perfectly.

I used two rolls of Top Flite MonoKote. All of the control surfaces were covered before being attached to the wing, stabilizer, and fin. I also used MonoKote to seal the gaps in the control surfaces.

When I was ready to attach the canopy, I found that it was dented. An e-mail to: informed them of my problem, and they immediately mailed me a new canopy at no charge.

I elected to fly with a .60 engine. After all, that is what this kit is all about. So I bolted an O.S. .61FX 2-stroke with a Slimline Pitts style muffler to the Great Planes adjustable engine mounts that were included with the kit.

A 12 oz. Great Planes fuel tank wrapped in 1/4" rubber padding was adjusted so the center of the tank was somewhat in line with the carburetor. Additional padding was inserted along the sides of the tank to eliminate any movement. A Great Planes Easy Fueler was installed in the right side of the firewall box. Later, a hole was made in the cowl so the fueling probe could access the Easy Fueler.

For control, I used a Futaba 6XA transmitter and an FP-R127DF seven-channel receiver. Three Futaba S3001 servos were mounted to the 3/8" by 1/2" basswood rails in the fuselage. The wide fuselage allowed me to easily position the servos in line with the pushrods.

The same type servos were mounted in each wing panel. I temporarily mounted the control surfaces and attached the nylon control horns. I used clamps to keep the control surfaces centered, and installed the clevises on the pushrods. The elevators were separate; each had a control horn. The two elevator pushrods were brought together about 1" behind the elevator servo and fastened with two 5/32" wheel collars.

I then connected the servos to the receiver, turned on the transmitter and centered the horns at right angles to the pushrods. The pushrods were then marked at the servo horn, bent at a right angle, cut off to 1/4" in length, placed in the outermost servo hole and secured with a Faslink that came with the kit. The throttle pushrod was installed with a clevis at the carburetor arm, inserted through the pushrod tube and attached to the servo arm with a Screw-Lock Pushrod Connector that also was included with the kit. The control surfaces were then removed and covered. Additional trimming was made after the model was completed using the transmitter's programming capabilities.

The four-cell NR-4J battery pack and receiver were wrapped with 1/4" foam and attached with Velcro to the plywood platforms I had fitted with screws crossways in the fuselage. That arrangement made it easy to shift them for balancing purposes. The antenna was routed through a pushrod that had been placed in position before the fuselage was covered.

I then set the travel of the control surfaces. Dual rate was set with the elevator's low rate 13 mm up and down and at high rate 17 mm up and down. The ailerons' low rate was set at 11 mm up, 8 mm down, and high rate, 17 mm up and 11 mm down.

A Great Planes C.G. Machine was used to set the balance 4-1/8" from the leading edge at the fuselage. To get a slightly nose heavy configuration with the cowling and wheel pants off, the battery pack was moved beneath the fuel tank and a 2 oz. Heavy Hub was used to secure the propeller. For the taxi test and first flight, I left the cowling wheel pants off. The taxi tests showed no particular negative traits. The lines were straight and, at 1/3 throttle, the tail lifted off the ground. After refilling the tank, and with the controls set at the low rate, it was time to fly. The take-off was smooth and the straight line flight was nearly perfect; gentle turns and figure eights came easy. All that was accomplished with minimal settings of the control trims. I used two clicks of throttle on the approach and cut it off as it flared for a neat two-wheel touchdown.

With the cowling and wheel coverings in place, the Heavy Hub was removed, the battery pack was moved aft as close to the servos as possible and 1-3/4 oz. of lead was attached to the fuselage immediately below the tail feather for a slightly nose-heavy configuration. I was concerned that the wheel coverings might not clear the dirt runway but found there was ample clearance.

I wrung it out with loops, Immelmanns, hammerheads, Cuban-8s, rolls, humpty bumps and half-Cuban eights. The O.S. .61FX pulled it through these maneuvers as smooth and as perfect as my fingers allowed.

I then turned it over to Eugene Kidwell the chief instructor at the Sun Valley Fliers club in Phoenix, AZ. After putting it through its paces, the only criticism Gene had was that more rudder was needed for the knife-edges. "This is a stable flying airplane and a pleasure to fly," Gene reported. "Great Planes has a winner with this one."

This plane is not for beginners. Intermediates, yes. This plane will do whatever you ask. Set the controls for minimum deflection and you can fly figure eights all day. A bit more movement and the basic aerobatic maneuvers are a snap. Set the control surfaces for full deflection, add a larger engine and you're ready to flip flop with the big guys. It is a quality kit well worth its price and backed by a caring company.

Reprinted with permission.
April, 2000 R/C Modeler Magazine
Editor: Dick Kidd