• Wing Span: 55 in (140 cm)
• Wing Area: 566 sq in (3652 cm²)
• Length: 49.5 in (130 cm)
• Weight: 5.75 lbs (2.6 kg)
• Engine: .40 - .46 2 - cycle
  (6.6 cc - 7.5 cc 2 - cycle)
  .60 - .70 4 - cycle
  (10 cc - 12 cc 4 - cycle)
• 4 or 5 Servos required

The Great Planes Ultra Sport 40 Custom ARF was referred to as a legendary aerobatic plane in one of the earlier advertisements. Some pilots at the local flying club say they just absolutely love that plane. When it was time ready to move up a notch in flying skills, the decision was made to try the Ultra Sport to see what the fuss was all about.

The Ultra Sport was unpacked as soon as it arrived and was inspected for defects and quality. One of the wing halves had a trailing edge piece, where the aileron torque rod is located, that was broken off and only held on by covering on one side. The decision was made to repair the piece with epoxy instead of shipping the wing back. The covering is a thick red and white plastic covering backed by a 1/8" of sheeted foam. This looks great because of its opacity but would be a nightmare to repair. There is also a lot of plastic used in the construction of this plane as can be seen by looking into the fuselage. Wood is not as abundant as it should be. The wings and tail feathers seem to be made of wood and covered with the foam backed material. The wheel wells are a nice touch to this model too.

Building began with the wing, where plywood joiners and a middle rib are epoxied between the wing halves. The larger wing joiner did not fit well into the pre-made slots on either wing half. When the slots were sanded to allow the joiner to fit, the slotted balsa rib split in half. This happened in the other wing half as well. The balsa ribs seemed to be pretty soft and not of sufficient quality for the application. A good bit of medium CA was used to repair and reinforce the the ribs. The wing finally went together with out further incident after more sanding. The plastic wings covers that went over the middle of the wing stayed on with a generous amount of CA and sanding for better grip. Retracts were not added and fixed gear was installed along with the supplied wheel wheel covers. These covers would not adhere to the front of the wells where the surface was most curved. A gap was left and then filled with plastic filler followed by some sanding and white paint.

The tail section was straight forward but a few problems were encountered. The CA hinges are pre-installed on the horizontal stabilizer and seemed very solid, in fact, too solid. The elevator was very hard to move and did not have much throw. Some constant pulling and wiggling of the elevator got it a little looser and more throw. It still remains a little stiff. The Rudder has to be glued with CA hinges to the tail fin and does not come pre-installed. This is necessary because the tail wheel mount must be installed before the rudder. The flat tail wheel bracket does not line up with the two holes for the screws that go into the fuselage, so this was left out and a piece if nylon string was tied around the screw that holds the stabilizer braces to the fuselage and to the tail wheel gear to keep it from going anywhere. Care must be taken when installing the rudder to the fin. Holding the rudder tightly will depressions in the foam covering and there is no way to pull the dent out!

The servos and pushrods are installed according to the instructions with bends added to the pushrods that give friction in the routing. The engine mounting and installation of the tail feathers went without incident. The canopy was mounted with four screws instead of messy glue and tape. The two piece plastic cowl seemed flimsy and would prove later to be true.

When it was time to mount the finished wing to the fuselage, it was found that the wing was 1/8" too big. A piece of plastic at the rear side of the wing saddle on the fuselage was removed and it still would not fit properly. Finally, the back edge of the plastic wing fairings were cut off and with a little force, the wing would fit.

An OS-40SF with an APC 10x6 prop was installed and a piece of lead was added to the engine mount to get it to balance as close as possible. Three inch rubber wheels were added to handle the grass runway.

The day it was flown was an evening with little wind and clear sky. It was put on the runway and slowly throttled up. It hopped along the bumpy runway and suddenly turned left on the ground. Full up elevator was applied to keep the tail on the ground and it took off just before going into the weeds on the edge of the runway. It climbed out steeply and then quickly leveled off. Small touches of aileron had it falling off a wing on which ever side aileron was applied. The elevator was overly sensitive even when set between the high and low rate throw settings. The aircraft handled like it was very tail heavy and would do things like mush into turns and not track very well. Low speed flight was tested along with a stall. It stalls very abruptly and falls off to one side into a vertical dive. Now that adrenaline was pumping at full bore, the decision was made to call it quits and do some mock landings.

On the first approach, the plane was kept at idle through the 180 degree turn onto final and about half way through it, the aircraft stalled and the nose yawed towards the ground in a vertical dive just 50' off the ground. Full power and full up elevator were the immediate response and the aircraft just barely missed the ground. The Ultra Sport bleeds off a lot of speed on the final turn onto final approach so some power has to be given. The first attempt at a touch down resulted in a broken wheel mount, so powered was applied to go around for another try. The controls were given to a club instructor who belly landed it very softly.

During repair, it was found that the four screws that go through the plywood gear mount plate to the block of balsa clipped to the landing gear had been left out during assembly. It had only been epoxied together. The four screws were added and the landing gear held up for the next few flights. The landing gear had hit the inside of the covering on the wing when the mount was taken out. It gouged out the foam behind the covering but the covering did not break. It is amazing how strong this composite covering really is.

Before the second flight, more lead was added to the engine mount and the plane appeared to balance a little forward of the suggested CG. The aileron throws were drastically reduced for this flight. This time, the throttle was quickly advance and the plane gradually climbed out in a more scale like take off. Only 2 clicks of left aileron was needed for hands off flight. Now, the plane tracked like it was on a wire and it did not mush into turns or bleed off a lot of speed. Rolls are very axial, loops are round, and vertical tracking is very good. Knife edge flight is just about sustainable and maneuvers like tail slides and hammerheads are really fun. This plane has plenty of vertical, though not unlimited, with the 40SF, which does not under power the Ultra Sport at all. This flight ended up in a dead stick landing when the engine leaned out. The plane was put into a vertical dive and a short down wind run to the turn on final approach was made. It was put down softly and it bounced a few times before coming to rest. The engine was readjusted and the Ultra Sport was taken up again. Shortly after take-off, there was a loud noice and something flew off of the front of the airplane. The left cowl halve ripped off the nose because of the aerodynamic loads on the cowl was constantly trying to separate the two halves. The plane was landed with out incident and the cowl recovered. The screws were still in the cowl and had been ripped right out off the fire wall.

The Ultra Sport 40 ARF would make a good third or fourth model, but is definitely not to be the next step after a trainer. The construction is not the greatest but the model does look very nice when it is finished. The problems mentioned here are ones that Great Planes should address. The amount of nose weight added was a bit ridiculous and only hampers performance. A good size engine that is out of the recommended range, such as a .60 2-stroke would probably give the extra nose weight for proper balance along with unlimited vertical maneuvers.