TOP FLITE SPITFIRE MK IX
by Pat Kinney
Name SPITFIRE MARK IX
Aircraft Type Sport Scale
Mfg. By Top Flite Models/Great Planes Model Dist., P.O. Box 9021, Champaign, Illinois 61826-9021
Mfg. Sug. Retail Price $249.99
Available From Retail Outlets
Wingspan 63 Inches
Wing Chord 11 Inches (Avg.)
Total Wing Area 687 Sq. In.
Fuselage Length 49 Inches
Stabilizer Span 20 Inches
Total Stab Area 126 Sq. In. (Approx.)
Mfg. Rec. Engine Range .61-.75 2-Stroke, .70-.91 4-Stroke
Rec. Fuel Tank Size 12 Oz.
Rec. No. of Channels 4-6
Rec. Control Functions Rud., Elev., Throt., Ail., Optional Retracts & Flaps
Basic Materials Used In Construction
Fuselage Balsa, Ply & Plastic
Wing Balsa & Ply
Tail Surfaces Balsa & Ply
Building Instructions on Plan Sheets Yes
Instruction Manual Yes (64 pages)
Construction Photos Yes
Radio Used JR 4-Channel w/5 Servos
Engine Make & Disp. Super Tigre 75 2-Stroke, w/T.F. Warbird Muffler
Tank Size Used 14 Oz.
Weight, Ready to Fly 154 Oz. (9 Lbs., 10 Oz.)
Wing Loading 32.2 Oz./Sq. Ft.
WE LIKED THE:
Ease of assembly, easy to read instruction manual, adjustable engine mount, and smooth flying.
WE DIDN'T LIKE THE:
The Spitfire was, and still is, a remarkable aircraft fully deserving its legendary record. This small aircraft somehow captured the imagination of the British people at a time of near despair. During the Battle of Britain ground crews worked throughout the night at airfields in Southern England, the pilots arriving before dawn to prepare for the days combat. The air was filled with the sound of Rolls-Royce Merlin and Griffon engines being readied for flight. Later the order to scramble (ring the bell and run like hell) sent the pilots sprinting for their aircraft, and engines once again roared into life. Top Flite has made it possible for you to fantasize those days in 1940 when you build and fly their Gold Edition Spitfire Mark IX, and I was fortunate enough to be given the opportunity to review this model.
The kit came in a sturdy cardboard box (L) 49-1/4" x (W) 11-1/2" x (H) 6" that was colorfully adorned with photos of the completed model and its specifications. Along each side of the box were color photos to assist us in our building process and color scheme. Inside the box were two full-size rolled plan sheets, a 64-page manual along with an abundance of balsa neatly grouped and packaged. The hardware package is as complete as I have seen and includes an adjustable engine mount, CA hinges, blind nuts, bolts, control horns, complete cleve set, tail wheel bracket, threaded pushrods, and pre-bent landing gear. There was a special cardboard divider secured to the inner kit box to protect the tissue-covered canopy from scratches.
The manual was very impressive as I reviewed each page to become knowledgeable of the construction procedure. There are over 200 photos and line drawings along with hot tips throughout the manual. On pages 8 and 9 are drawings of each die-cut sheet in the kit. Each pattern is identified for quick cross-reference when removing the die-cut parts. Some plywood parts were crisply cut by laser and show very low char. Just to play it safe, the parts were sanded and brushed to rid the edges from any charred wood for good glue bonding. The ABS vacuum formed parts such as the cowl (two pieces), cowl blisters, wing fillets and gun blisters, were of good quality and thickness.
While not a first timer's kit, any builder who has built a trainer or two and can follow instructions should be able to assemble this kit reasonably well. Being an all-wood kit, it will appeal to many modelers who enjoy the building phase of our sport as I do, and especially to those of us who are attracted to vintage scale models.
After reviewing the plans, it was decided to build the Spitfire without flaps or retracts. For once I wanted to build a scale model right from the box without a lot of additional electronics, this way a simple 4-channel radio could be used with one additional servo for dual ailerons. The only other items added were Top-Flite's Spitfire cockpit kit and an in-cowl muffler with header for our SuperTigre 75 2-stroke.
The vertical fin and horizontal stabilizer are built over the plans using rib/tab construction, then sheeted with 1/16" balsa. The rudder and elevator are ribbed over a center core with the addition of root and tip blocks, then sanded to shape.
Wing construction starts with the outer wing panels and are built over the plans. The main spars are of good quality straight grain basswood, reinforced with balsa shear webbing. Each rib is different in length to give that Spitfire elliptical shape to the wing. Jig tabs that are a part of the ribs are located at the extreme trailing edge and break off before sheeting. There are notches in the appropriate ribs for installing the landing gear and servo hatch rails. The center section gives strength to the wing by the use of interlocking wing joiners. The outer wing panels press into the center section and all three parts are glued together. The wing is then placed upside down on a very unique jig system to keep the wing in alignment, while the 30-minute epoxy cures. I found the soft 1/16" balsa wing skin sheeting easy to apply over the curved wing surface, but the least amount of pressure between ribs would break through the balsa surface. Even if I covered the wing with MonoKote, the sheeting would still break beneath the film. For this reason, it was decided to fiberglass the wing and the fuselage. The rudder, elevator, and ailerons were excluded as they are open-framed and get covered with MonoKote.
The fuselage uses interlocking construction and is built in two halves, top and bottom. The top is built directly over the plans. Two main stringers are pinned to the plans and the formers were supposed to fit between the two main stringers—not so with our review model. The notched formers would not completely span the two main stringers. Either the plans were over-sized or the formers were too small. If it was not for my years of scratch-building, I would probably be intimidated. To solve the problem, I taped all the inter-locking parts together and set them over the plans. I then moved the main stringers in to meet the formers from B1 to the stab saddle.
A club member building the same Spitfire kit also experienced the problem and called Top Flite, and I believe this problem has now been corrected. Both main stringers are grooved on the outside surface to accept sub-stringers, which provide a stop for the sheeting. With all the stringers in place and the sheeting on, the stabilizer was glued to the stabilizer saddle and the vertical fin to the stabilizer. After the glue was completely dry the fuselage half was lifted from the plans and turned upside down on a support stand. The bottom half of the fuselage went together quite well, right up to seating the wing on the wing saddle and tapping the mounting holes.
Scale building is all about detail, and that is exactly what Top Flite has provided in their Spitfire scale cockpit interior kit. The scale cockpit is an optional item purchased at your local hobby shop. All parts are vacuum-formed light ABS plastic. I suggest that you reinforce the back of each part with 3/32" sheet balsa, which is easy to inlay and glue in place with Pro-CA+ medium. Each reinforced panel will now slide in and out of its position until you are ready to permanently glue each one in place.
The engine specified range is 61 to 90 cu. in.; we installed an older Super Tiger 75 cu. in. 2-stroke to power our Spitfire along with Top Flite's in-cowl warbird muffler and header. Since the muffler is so far from the engine and the silicone tubing that came with the muffler was too short, we purchased from our local high performance auto parts store a piece of 3/4" (19 mm) (inside diameter) high-heat silicone tubing to connect the header to the muffler. The supplied engine mount is fully adjustable to accommodate a wide range of engines. A 14 oz. Great Planes fuel tank was installed with a 13 x 6 Top Flite prop propelling our Spitfire.
I had completely forgotten encountering a bearing malfunction with this engine some time ago and had not replaced the bearing. Since the 75K rear bearing could not be found locally, a toll-free call was made (800) 332-3256 to Boca Bearing in Boca Raton, Florida. Not only do they have a toll-free number, but their shipping and handling is absolutely free in the United States and Canada. The bearing was paid for by credit card and came by mail three days later in a padded shipping envelope. Along with the bearing came complete instructions on the easiest way to install the new bearing. I think their policies and procedures are great.
I chose not to glue the servo tray in place as outlined in the manual. Spacers were glued between the floating left and right crutch ends and the main stringers. I then glued to each side of the left and right crutch 1/2" x 3/8" x 4-1/2" hardwood servo tray rails. Placement of the rails were on the same plane as the proposed servo tray. The servo tray was then modified and attached to the servo mounting rails with #2 x 3/8" cap screws.
Since we did not install retracts, the bottom servo tray and rails were eliminated. The receiver is wrapped in 1/8" foam and packed away under the servo tray. Standard-size servos are used to drive all the control surfaces.
All the control surfaces were covered with Top Flite gray MonoKote. Since the control surfaces were open-framed rib construction, heat shrinking the MonoKote over the ribs gave the control surfaces a scale-like appearance. The wing, fuselage, horizontal stabilizer, and vertical fin were covered with K&B medium fiberglass cloth using K&B polyester resin for a bonding agent. K&B Ultrapoxy primer and paint was used to finish the Spitfire. K&B Ultrapoxy is a two-part mix using equal amounts of paint (A) to catalyst (B). To match the gray MonoKote, add a few drops of black to white until you have the right blend. Olive drab is attained by adding small amounts of black to yellow until you are pleased with the depth of color. Always experiment by using drops of paint on a small pallet. K&B satin finish (part B) was used for the catalyst. The directions on the K&B paint can says "Not to thin," although some thinning is always needed when using a spray gun.
Most shudder at the thought, when it comes time to glue a canopy to the fuselage. To make a difficult installation easy, masking tape straps were used to keep the canopy compressed against the fuselage top. Three c-clamps were made from coat hanger wire to hold the sides in place. The wire was bent to an oval shape with the ends cut off diagonally to make a sharp point. The opening of each c-clamp should be the width of the canopy where it comes in contact with the fuselage and deep enough to clear the top of the canopy. Bend the c-clamps in for more tension and glue the canopy in place with formula 560, it cleans up with water and dries clear.
The manual gives you control surface throws for both high and low rate settings. All control surfaces could be set halfway between the recommended high and low rate and this gives some leeway for adjustment should any one of the control surfaces be too sensitive, or not sensitive enough after the first flight. The C.G. is located 4-1/8" back from the leading edge at the wing root and required 19 oz. of nose weight to balance the review model at the specified C.G.
After a thorough 25-point check list provided in the manual, we were ready for our first test flight. Warbirds always get a lot of attention at the field, especially if others find out it's the first flight. After all the nice compliments, the tank was filled and the throttle set slightly on the rich side. As I taxied out to the runway, we noted the tail bounced easily. That meant, on acceleration of the engine, we could encounter a problem, and it certainly worked out that way. Out at the center of the runway, I gradually opened the throttle and before I knew it, the Spitfire was up on its nose! Back to the pit for a new prop. The Spitfire was once again taxied into position for take-off. This time I held a bit of up elevator to keep the tail down, controlled right rudder to keep it going in the right direction until the plane picked up some speed. Then as I eased off of up elevator, the tail came up nicely this time, and the Spitfire lifted off majestically.
Climb-out was smooth with a gradual left turn, which was held corrected with the stick until aileron could be trimmed for level flight. Both slow flight and stalls were initiated at a safe altitude. Slow flight characteristics were very good with responsive controls, but to a point. Our aim was to gradually decrease the throttle while applying more and more elevator until the plane stalled. Fortunately, I didn't forget that critical test. As the plane approached stall speed, it rolled over sharply into a snap roll. Oops! That really came as a surprise.
I knew the wing was built with proper washout which usually helps prevent that kind of thing. Despite the washout, it did a real good snap. That meant I would need to come in relatively hot to keep the airspeed well above the critical stall speed. A snap on final doesn't give you time to do much but pick up the pieces.
After a few passes and a couple trim adjustments, I had a good feel for the controls. It was now time for the simulated dog fight with the Phantom Focke-Wulf 190. To confuse the Phantom pilot, the Spitfire was given full throttle and up elevator into a half inside loop rolling out at the top. At the other end of the field, the Spitfire was rolled upside-down, did a 180 by finishing in a split-S. With Focke-Wulf 190 still on my tail, I did a couple consecutive loops, rolls, and inverted flight. It was my friend Ben's tap on my shoulder that brought me back to reality. WOW! What a flight.
Once back on the ground, we discussed what would make the Spitfire's elliptical wing more stable at stall speeds. A good friend and one of the more skilled scale pilots at our field, suggested that I raise both ailerons 1/8" from neutral. This would allow the tips to continue giving lift while the inner area of the wing was losing lift when landing. This sure sounded realistic to me, so I went up for another flight to check it out. While the second flight indicated that raising both ailerons did help, I still felt the only wise approach is to come in hot until the wheels touch, then go to idle. If you've ever seen movies of Spitfires coming in for a landing on a grassy field in England, you'll recall that they keep up the airspeed until the wheels are safely on the ground.
Even though Top Flite's Spitfire is a great flying scale model, do not expect it to fly like a pattern ship nor land like a trainer. It does all the realistic maneuvers normally called for at a scale contest and then some. Other than the problem mentioned in construction, it went together very well. I found the Spitfire very stable in flight and a fun warbird to fly, and you should too if you decide to build this neat-looking model.
Reprinted with permission.
August, 1999 R/C Modeler Magazine
Editor: Dick Kidd