by Ken Kehlet

Ultimate Bipe photo SPECIFICATIONS

Name: ULTIMATE .40
Aircraft Type: High Performance Biplane
Mfg. By: Great Planes Model Mfg. Co., 2904 Research Rd., Champaign, Illinois 61826
Mfg. Sug. Retail Price: $199.99
Available From: Retail Outlets
Wingspan: 43-3/8 in.
Wing Chord: 8-1/2 in.
Total Wing Area: 742 sq. in.
Fuselage Length: 47-3/4 in. Stabilizer Span: 19 in. Total Stab Area: 110 sq. in. (approx.)
Mfg. Rec. Engine Range: .40-.46 2-stroke, .48-.70 4-stroke
Rec. Fuel Tank Size: 10 oz.
Rec. No. of Channels: 4
Rec. Control Functions: Rudder, Elevator, Throttle, Aileron

Basic Materials Used In Construction:

Fuselage: Balsa & Ply, ABS Plastic Cowl
Wing: Balsa & Ply
Tail Surfaces: Balsa
Building Instructions on Plan Sheets: Yes
Instruction Manual: Yes (48 pages)
Construction Photos: Yes (175 photos)


Radio Used: JR 388 PCM

Engine Make & Disp.: O.S. .70 Surpass 4-stroke
Tank Size Used: Great Planes 10 oz.
Weight, Ready to Fly: 108 oz. (6 lbs. 12 oz.)
Wing Loading: 20.9 oz./sq. ft.


Well written instruction manual. Full size plans (2) with part numbers for the required accessories. Attention to safety and extra attention to small details both in the kit and in the instruction manual. Flight performance.

No problems noted.

When I received the very large box from R/C Modeler Magazine, I found, inside the outer box, another box containing a Great Planes Ultimate .40 High Performance Biplane kit, and along with the kit, I found two large plastic bags with an assortment of modeling accessories that Great Planes also provided for the review. The plastic bags contained just about every required accessory for building and completing the model. I had a new O.S. .70 Surpass 4-stroke looking for a home, and per the kit information, my engine would fulfill the maximum power recommendation.

The colorful kit box measured 48.5 x 10.75 x 4.5 inches. Upon opening the kit, I was impressed with the very informative, well-written 48-page instruction manual. I counted 175 photos and several drawings as I scanned through the documentation. I unrolled the two (2) large plans, 38" x 50" and 41" x 60", cleared off the second workbench, and spread out the drawing. Lots of details, notes, and part numbers are printed on the plans. I like to compare the plans to the instruction manual and the kit piece parts to the plans prior to any assembly. I started by laying out the die-cut sheets and identifying them with the drawings in the manual and locations on the plans. The die-cut was excellent, neat and clean, and the straight wood, sticks, spars, and sheet wood was all of good quality. Plastic parts, cowl, and wheel pants were formed and packed well. The large clear plastic canopy was protected and packed within a separate compartment inside the box. With all the hardware in the kit, and all the extra goodies that were supplied by Great Planes, including bottles of G.P. Pro Thin, Medium, and Thick CA, and GP Pro Epoxy; all I had to do was get started. Wax paper was spread over the plans, then following the instruction manual step-by-step, construction was started.

I knew that my engine selection would make a "nose heavy" model, therefore, no attempt was made to build a light tail section. I figured that I could shift the radio gear back far enough to get the proper balance.

The Great Planes "Pro" adhesives were used throughout the construction of the model. By the way, "Pro" is the only brand of CA that has a "use before" date stamped on the bottom of each bottle. The lower wing assembly went together quite fast due to the "jig tabs" on the bottom of each symmetrical rib and the pre-notched leading and trailing edges. The weight of a steel straightedge and the pins through each fore and aft "jig tab" holding the ribs in position assured a straight true wing. The G.P. Pro Thin CA was applied sparingly at each joint. The remainder of the wing was completed in the normal fashion by following the steps in the instruction manual. A plywood web was epoxied in the center section, and 1/16" balsa webs between the upper and lower spars between each rib out to the tips. Small holes were poked through each web to let the air pass through when shrinking the covering material. 1/16" sheeting was also used over the trailing edge and over the leading edge as in the normal "D" tube construction.

The fuselage is built very strong. As I followed the steps in the manual, I was certain that the design would be capable of supporting the power of my .70 Surpass. As the construction progressed, each part fit the way it was supposed to. The fuselage was completed and the upper wing was built. The bare bones were assembled and alignments were checked with an incidence meter. Very little cutting or trimming was required during the building of this model.

Plastic Parts:
The cowling and the wheel pants went together quite easily. I then decided to fill in all the seams. After several times of filling and sanding, I sprayed on the first of several primer coats with light sanding between each coat.

I selected Top Flite's Super MonoKote covering in Metallic Red, White, Metallic Blue, and White LustreKote paint. One application of Top Flite's White LustreKote paint finished off the cowling and wheel pants.

I mounted my engine and installed the fuel tank, fuel lines, and fuel fill valve that G.P. had sent as separate accessories. Following the tips in the manual, holes were cut in the cowling to accommodate my O.S. .70 Surpass. G.P. also supplied a 2-1/2" dia. spinner that matched the cowling.

Final Hookup:
While installing my JR PCM radio equipment, I appreciated the "hardware" included in the kit. Besides the screws, nuts, and bolts for each purpose, unique guides for pushrods, hinges, and clevises, G.P. included 3/16" lengths of silicone tubing retainers that are used to prevent the clevise from opening when attached to the control horns. This little extra safety feature should be on everyone's preflight checklist, but this is the first time that I have ever found such items included in a kit.

The servos and battery were installed as far back as possible. With an oversize 800 mAh flight battery in place, balance was checked and found to be just slightly nose heavy. The recommended finished weight was 5.5 to 6.5 lbs.; my Ultimate, with its oversize engine and battery, tipped the scale at 6.75 lbs. with 742 sq. in. of wing area; it gave a wing loading of 20.9 oz./sq. ft. I could save at least 10 oz. if I used a standard battery pack and a .46 size 2-stroke engine. Maybe later, but for now, I like what I have.

Following an additional safety check and radio range check at the flying field, the tank was filled and the first attempt was made to start the new O.S. .70 Surpass. A light prime, Ni-Starter attached, and the prop was pulled through compression by a firm hold on one blade. A "bump" was felt, and we were ready. Two flips and the O.S. came to life at high idle. The high-speed needle was set slightly rich and power was checked through the entire speed range. The idle trim was reduced and the O.S. continued to perk at 2400 rpms—not bad at all, for a new engine right out of the box. Another radio range check with the engine running, 15 minutes of break-in, and I was ready for the first flight.

Ground handling was very good through the grass and out to the runway. Controls were again checked and the throttle was advanced, a little right rudder was applied and the tracking was straight and true as it gained speed. A touch of elevator provided a smooth lift off. Climbing at half throttle, I made a slow procedural turn away from the pits. After a few nice and easy turns, the trim was checked and one click of right aileron was required. A little more power was applied and up into loops, rolls, split S, rolling figure 8, spins, inverted flight, and knife-edge. A few more holes were burned into the sky and then set-up for an easy landing. Successive flights were without incident, slow speed flight was good with full control at all times, landings were smooth on the main wheels or slow 3-point.

Great Planes has again provided a well-designed, well-engineered R/C kit. Their step-by-step instruction manual, expert building tips, and attention to details, reward the modeler with smooth, predictable flight performance that can make any R/C pilot look good.

This is not a beginner's kit. This R/C model will do every aerobatic maneuver that the pilot is capable of performing and yet it will still slow down and settle in for a perfect landing. A modeler who has built and mastered the control of a Pattern type, low wing, model will enjoy building and flying the G.P. Ultimate .40 Biplane.

Reprinted with permission.
November, 1998 R/C Modeler Magazine
Editor: Dick Kidd