Kyosho F-86F

Kyosho F-86F

Ziroli, Nick Sr

Pull-start power for a ducted fan!

If you have been paying attention to trends in RC models, you are aware that almost– ready-to-fly (ARI) models have arrived in a big way. They come in all types-trainers, scale, aerobatic, fun-fly and park flyer-and sizes, from backyard flyers that weigh just a few ounces to 1/3-scale giant acrobatic planes. It was only a matter of time until someone came out with a plane like Kyosho’s new F-861F Sabre ARE This semi-scale, 39.5-inch-span warbird comes complete with a pull-start O.S. .15 CV ducted-fan engine and fan unit, ready to install. As it is front Kyosho, the excellent quality and value of the kit come as no surprise.

In my review of the Kyosho of electric Learjet in the January 2001 issue of Model Airplane News, I wrote how impressed I was with the kit and its performance, Like the Learjet, the F-86 is an innovative and well-engineered ductedfan model. but that is where the similarities end. ile Learjet is all sheet-foam construction; the F-86 has a fiberglass fuselage and built– up, film-covered flying surfaces. Most notably, the F-86 is powered by an O.S. .15 CV-DF engine with a pull-starter and tuned pipe, all of which are included. The colorful box is well packed, and the photos serve as a guide for applying the many graphics that dress up the model. The fuselage is fiberglass with a silver finish molded in. The built-up balsa wings and tail surfaces are covered in multicolored film; they are light and expertly built. SPECIFICATIONS

Model: F-86F Sabre

Manufacturer: Kyosho

Distributor: Great Planes Model Dist.

Type: semi-scale, ducted-fan ARF

Wingspan: 39.5 in.

Wing area: 341 sq. in.

Airfoil: flat bottom

Weight: 58 oz.

Wing loading: 25.4 oz./sq. ft.

Overall length: 37 in.

Radio required: 4-channel; 4 servos

Radio used: Airtonics RD-6000 Super transmitter, 92777 receiver and four 94556 Microlite servos Engine Used: O.S. .15 CV-DF with tuned pipe (included)

Prop used: 3.5-inch-diameter fan (included)

Price: $429.99

Features: fiberglass fuselage and prebuilt, film-covered flying surfaces and includes ducted fan, engine and tuned pipe; kit includes everything needed for assembly (except fuel tubing); lots of colorful graphics.

Comments: its well-engineered design looks great in the air. The F-86F requires a paved surface for taking off with wheels, but it can be bungee-launched from grass. The engine and fan unit operated flawlessly with a minimum 25-percent-nitro content (45-percent preferred). It has good flight characteristics, but it isn’t for novices.

Hits

* Excellent design and parts fit.

* Very complete kit.

* Nice scale appearance that looks great in the air.

* Excellent power system.

Misses

* Many more tools required than listed in the instructions.

* Written instructions lack detail and clarity.

ASSEMBLY

* Wing. Construction starts with the wing. The ailerons must be hinged, and the hinge slots are precut in both the wings and ailerons. Glue the included sheet plastic hinges in place with thin CA. Glue the aileron-control torque rods into each aileron with a light coat of epoxy. Join the wing panels with 30– minute epoxy. Keep some solvent and paper towels handy to clean off the excess epoxy before it cures. Cut away the covering to glue the servo-mounting plate to the wing. I used Airtronics Microlite high– torque servos. These are shorter than the holes provided in the servo plates, so I cut the aileron plate in half and shortened it to fit the servo. I filled the other servo mounts with scrap and glued a 1/16-inch ply piece over each end of the plate to close it up. It is necessary to drill out the servo arms with a no. 51 drill to fit the pushrod wire. Carefully lay out the holes for the front wing hold-down dowels, drill them and epoxy the dowels in place. Mount the landing-gear struts and wheels to complete the wing.

* Fuselage. The fuselage assembly is a little out of the ordinary, so be careful to follow the instructions, except where noted. The instructions are well illustrated with excellent photos and hardware descriptions; however, they fall short on descriptive text. The Japanese to English translation is very poor and in some cases comical. Take time to study each step and understand it.

First, install the plywood brace for the front wing dowels and the balsa air ramp in front of it. All the plywood parts are laser cut and fit well. Open the gun ports up to 6mm. I did not find it necessary to cut notches in the wing saddle to fit the formers into the fuselage. Before installing the two formers, make sure they fit into the fuselage. They will show on the outside of the fuselage if they fit too tightly. A few passes around the outside edge with sandpaper will bring them down to the proper size. Once they fit, mount the ducted-fan shroud on the front former with four screws.

At this point, jump ahead to step 12 and make up the front former. Make sure the former fits on the shroud before you add the bell-mouth mounting ring, and don’t fill the inside comers with epoxy-I used thin Zap for this. Jump ahead again to step 14. Trim the bell mouth to fit inside the fuselage and inside the front former ring against the shroud. It is much easier to do this with the parts outside the fuselage. You want a good, smooth transition from the bell mouth to the shroud. Fit the shroud and rear former into the fuselage but don’t glue anything yet. Epoxy the wing screw-mounting plate in place. It is critical that this is located correctly, or the front former will not fit. The front edge of the plate must be back from the wing opening at least 17mm. I made a simple depth jig to position it. Mount the wing and make sure it is square to the fuselage.

Put the front former in place and secure it to the shroud with four screws. The shroud-former assembly should be located so the rear face of the aft former is even with the front edge of the engine hatch. Tack it in place with thick CA or epoxy. Install the pushrod and fuel tubes and epoxy or CA the formers permanently; I used a bead of Flex-Zap II. Now epoxy the bell mouth to the shroud and fuselage. Next, epoxy the curved, plywood screw plates inside the. engine-access opening. It will be very difficult to do this at step 34 (as the instructions recommend) when the area is all cluttered with the engine, fuel lines and pushrods.

* Engine installation. Attach the engine to its mount and add the throttle linkage, manifold and tuned pipe. Bolt the engine assembly into the shroud center body and install it through the tailpipe. This is another time to skip ahead. Go to step 23, and install the fuel lines from the transfer tubes to the carburetor and pressure tap. These are much easier to connect before the engine is all the way forward in the shroud. For some reason, fuel line is not included. This is strange, since it is such a complete kit and the box states “Everything except a radio and starter set included”; but the instructions correctly note that it must be purchased separately.

Mark the hole locations for the needle valve and rear tuned-pipe mount. The needle valve’s height is 90mm, but it would have been better at 85mm. I drilled an ch inch hole on the opposite side of the fuselage for access to the idle-mixture screw. This .15 has an auto-mix-type carburetor usually found only on larger engines. Make a 3/4-inch needle-valve extension from pushrod wire. Next, install the fan and spinner; this requires a 12mm socket and a 2.5mm Allen wrench. These are not mentioned in the required tools list. Though also not mentioned, it would be wise not to tighten the drive nut against the pull– starter, as this may damage the ratchet or starter cord. I inserted a piece of hardwood into the shroud to prevent the fan from turning while the drive nut was tightened. Add the spinner to complete the engine installation.

Next, install the nosewheel assembly; this requires a 1.5mm Allen wrench. The nose– inlet cap is also epoxied into place at this time. I made a change here: I was certain that with the engine and tuned pipe so far aft, this would be a tail-heavy model and would require a fair amount of nose weight. Because of this, I picked the largest battery I could fit in the space provided-an Airtronics flat 6V, 500mAh Ni-Cd pack. I cut a hole over the inlet to allow the battery to extend as far forward as possible and did not epoxy the inlet cap on at this time so more weight could be placed inside it, if required. Screws and decals hold it securely without epoxy.

A flat, space-saving fuel tank is included that is designed to reduce the internal fuselage drag, and it has fill, vent and feed lines. Hook-and-loop tape holds the tank in place. The motor includes a priming bulb like those seen on larger gas engines. For easy engine starting, it really is required because there is no access for an electric starter to spin the engine fast enough to draw fuel on its own, and the carburetor intake cannot be reached for choking. There is a fuel– system diagram, but it is not clear which fuel line is going to which fuel-tank outlet. Also, there is no mention of where to locate the fuel fill or that it must be plugged after filling so the pipe pressure can work. I chose to epoxy a piece of A-inch tubing into one of the gun ports and connect it to the fill tube that goes to the bottom of the tank (remember that you are working upside– down through the wing opening). I capped the fill tube with a short piece of fuel line with a plug in one end. This fuel system works very well; the engine run was reliable from takeoff to landing.

* Tail. Next, complete and install the tail surfaces. Epoxy the wire elevator horns into the elevators and insert the elevator hinges into the precut slots, as was done with the ailerons. Epoxy the stabilizers and screw them into place. Hinge the rudder to the fin. Jump ahead a step before you epoxy the fin in place; it is a lot easier to install the pull/pull horn assembly before the fin is on the fuselage. Now epoxy the fin in place. Add the red graphics to the base of the fin and stabilizer before you install the pull/pull cables. Mount the rudder servo in the center of the mounting plate. A small hole must be cut in the bottom to reach the front servo-mounting screws, and I made up the pull/pull cable ends in reverse order of the instructions-servo side first then to the rudder horns. Setting the cable length is critical and much easier to do outside the fuselage. Drill out the servo-arm hole for the nosewheel-pushrod connector with a no. 48 drill bit. The steering pushrod goes on the opposite side of the servo from the rudder connection to synchronize steering and rudder throw.

Fit and glue the cover plate below the stabilizer inside the tailpipe. Solder the threaded links to the ends of the elevator pushrods. Insert the pushrod through the proper guide tube, and connect the links to the elevator horns. Adjust the links so both elevators are the same at neutral. Mount the elevator and throttle servos, drill the servo– arm holes and connect the pushrods. Mount the switch as shown, then wrap the battery and receiver in thin foam padding and position them in the nose, battery first. The space is tight, but my Airtronics 92777 receiver easily fits. Set up all control-surface throws as instructed.

Cut the required notch and hole on the engine cover, and screw it in place; the plywood screw plates are already epoxied in place. Drill a no. 58 hole through the cover into the fuselage at each screw location. Pre– thread each hole in the fuselage by inserting a screw. It takes a lot of pressure to screw it in, so support the inside with your fingers to prevent damaging the fuselage. Be sure this cover is in place before you fly the F-86.

* Canopy and graphics. Trim the tinted canopy to fit the fuselage. I trimmed it to the lines molded in and found it to be a little small, so cut it oversize and trim to fit. I didn’t like the idea of cutting big holes in the canopy sides for additional air to the fan. This is a nice-looking model, and I felt it ruined its appearance; besides, flush side holes are not very efficient. If a hole is necessary, why not make the canopy clear, so it isn’t so visible? The front three window sections could be cut out, leaving just the canopy framework. This would look better and make a much more efficient air scoop. It might even make the non-scale fuselage side scoops unnecessary. I chose not to cut the holes where instructed. I test-flew the F-86 without holes and then cut the flat windscreen out. There wasn’t a significant performance increase, but it does supply more air to the fan, and the hole is much less noticeable than it would have been on the side.

Two large graphics sheets must be cut out and applied to the model. A 3-view in the instructions and the box art serve as a guide. Cut out each item, lay it in place, and mark its position with pieces of masking tape at each comer. I used Windex to help position the bigger pieces.

FINAL TOUCHES

The last thing to do is balance the model. The specified balance point is 185 to 195mm back from the wings leading edge at the fuselage. I added 1 1/2 ounces to balance it at 190mm. I had not attached the inlet cap in anticipation of adding weight inside it. After test flights, I added another ounce to balance it at a more stable 185mm.

It will become apparent the first time you prepare to run the engine that it is difficult to tell when the fuel tank is full. Watch the overflow line that runs to the tuned pipe through the canopy; when fuel flows through it, the tank is full. I tilt the fuselage back on its tail and pull the starter cord so the piston closes the exhaust port. With the exhaust closed, the engine won’t flood if fuel gets into the exhaust manifold. Be sure to cap the fill line before you start the engine.

There is no mention of what nitro content the fuel should have, but these smaller engines like a high nitro fuel. I started with 25-percent-nitro content, which worked OK; I later obtained some Wildcat “Promix” 45– and 65-percent-nitro content fuel to see how this might improve performance. After testing all three, I feel the 45-percent is the best choice. It raises performance without raising the cost too much, and it’s still easy on glow– plugs. For those who want power at any cost, Wildcat 65 percent is the way to go.

On the first flight, the F-86 was overly sensitive to both pitch and roll. I added an extra ounce of nose weight to bring the balance point to 185mm behind the leading edge. I also reduced the aileron throws a little. I recommend no more than 3/16-inch throw each way. If you have duel rates, set the low to 1/8 inch-it doesn’t take much. The recommended 3/8 inch of elevator travel was good. One last change I made to help stability was to reflex the ailerons up 3/32 inch for neutral. Lay a straightedge on the bottom of the wing parallel with the silver and blue separation line, and adjust the links for a 3/32-inch space between it and the trailing edge of the aileron. This adjustment reduces its tendency to spin at low speed.

CONCLUSION

The Kyosho F-86F, typical of all Kyosho products, is very well engineered and manufactured. This is not a model for the novice, and Kyosho tells you that up front. It is fun to assemble, though the instructions leave the builder guessing at times. The quality of all the parts is excellent, the workmanship is outstanding, and during all of our flight tests, the engine ran flawlessly. Trimmed properly, the model flies very well; spectators and fellow modelers really enjoy watching this F-86F Sabre in the air.

Airtronics, 1185 Stanford Ct., Anaheim, CA 92805; (714) 978-1895; fax (714) 978-1540; www.airtronics.net.

Kyosho; distributed by Great Planes Model Distributors, P.O. Box 9021, Champaign, IL 61826– 9021; (217) 398-6300; fax (217) 398-1104; www.kyosho.com.

Wildcat Fuels, 3005 Park Central, Unit T, Nicholasville, KY 40356; (606) 885-5619.

Copyright Air Age Publishing Dec 2001

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