TOP FLITE GIANT P-51D MUSTANG
by Chris Abate
Name P-51D MUSTANG (Giant Scale)
Aircraft Type WWII Fighter
Mfg. By Great Planes Model Dist., P.O. Box 9021, Champaign, Illinois 61826-9021
Mfg. Sug. Retail Price $399.99
Available From Retail Outlets
Wingspan 84-1/2 Inches
Wing Chord 14-3/4 Inches (Avg.)
Total Wing Area 1,245 Sq. In.
Fuselage Length 73-1/2 Inches
Stabilizer Span 29-7/8 Inches
Total Stab Area 157 Sq. In.
Mfg. Rec. Engine Range 1.8-2.4 Glow, 2.1-4.2 Gas
Rec. Fuel Tank Size 24 Oz.
Rec. No. of Channels 6-7
Rec. Control Functions Rud., Elev., Throt., Ail., Flaps, Retract Gear
Basic Materials Used In Construction
Fuselage Balsa, Ply & Plastic
Wing Balsa, Ply & Plastic
Tail Surfaces Balsa & Ply
Building Instructions on Plan Sheets Yes
Instruction Manual Yes (59 pages)
Construction Photos Yes
Radio Used JR XP8103
Engine Make & Disp. U.S. Engines 4.2 w/18 x 10 T.F. Prop
Tank Size Used 24 Oz.
Weight, Ready to Fly 312 Oz. (19-1/2 Lbs.)
Wing Loading 36 Oz./Sq. Ft.
WE LIKED THE:
Quality of materials, detailed plans and instruction book, and flight performance.
WE DIDN'T LIKE THE:
Difference in parts to plan dimensions. See text.
The North American P-51 Mustang is probably one of the most famous fighters of WWII. The Mustang could cruise around the skies at 440 miles per hour and operate at a ceiling of 41,900 feet. Its range with drop tanks was from England to Berlin and beyond, this with the Merlin Engine. 14,490 aircraft were produced. All the above are some amazing facts for their time, but the one that to me is most impressive is that the Mustang was designed, built, and test-flown in only 117 days. The P-51's primary mission was to escort the bombers to the target and establish allied air superiority. History has shown it performed its task and did it well.
The name Top Flite has been around for a number of years, and within the past couple of years they have revamped their warbird line into the Gold Edition Warbird Series. Some redesign and up-to-date building techniques were established which made a popular and well-done kit line even better. Then, just when you think it could not get any better, they start to increase the size of the kit line. The first to be Super Sized is the P-51 Mustang.
You get a feel for the size of this kit when you first see the kit box, which measures a big 49-1/8"L x 6-1/8"H x 15-7/8"W. Right from the get-go, you will be impressed with the graphics that are on the top and side of the box. Then, when you open the box, you will find a neatly packed and bagged lumberyard/hardware store. I did not have any damaged parts, and all parts were easily identified.
The plan sheets come as four sheets: two for the wing and fuselage; a simple trim and taping of the sheets provide you with a full drawing of the wing and fuselage. The now "two sheets" measure 89" x 36", you better have some place other than the kitchen table to build this one. Opening the 59-page instruction manual, you will notice it covers everything from tools needed to test flying, and with enough photos and illustrations to leave nothing to the imagination.
The construction as per the instructions starts with the tail group. The tail group is made up mostly of balsa, ply is used in the high stress areas. The stab is first. No slab sheets here, it has an airfoil shape and the ribs have building tabs to aid in alignment while it is being built. The stab is sheeted with 3/32" balsa, as well as the elevators. The fin or vertical stab is next up and follows the stab as far as the building goes; it, too, is airfoiled in shape and also gets 3/32" sheeting. The rudder is a 1/8" balsa sheet which has been cut to profile and ribs are glued to each side and sanded to shape.
The wing is next and, like the stab and fin, each rib has building tabs to aid in the alignment and washout. They are then removed prior to sheeting the wing. The main spar is made up of 3/8" x 1/2" x 42" basswood. The main spars run on top and bottom of the ribs in the conventional manner. 3/32" balsa sheer webs are added to both sides of the spar running the entire length of the wing. This arrangement makes a very strong spar. The ribs that hold the retract units are 1/8" ply and have a ply doubler on each side. All the other wing ribs are balsa except for the center section. All ribs are notched for the spars and have lightening holes, the ribs for the retract units also have slots cut to hold the maple rails that the retracts bolt to. These slots were cut incorrectly on our review model and, once the rails are glued in place and the retract units installed, the unit will protrude through the top wing sheeting. The simple fix here is to add a shim between the retract housing and the maple rail which will lower the housing in the wing. Let me take this time to mention that the plans are drawn showing the use of retracts, for both the wing and a retractable tail unit in the fuselage. To build a kit like this and not install retracts ... well is just unheard of.
By the way, Robart now includes in their landing gear kits an adjustable air valve instead of the non-adjustable one that used to be supplied with the gear. The adjustable valve allows you to adjust the speed at which the gear is deployed and retracted. This enhances the scale effect of the gear when it is in operation. Instead of the gear slamming up and down at the speed of light, they can be adjusted to duplicate the action and speed of the full-scale prototype. The adjustments are easily accomplished by turning small adjustment screws on the valve, much like adjusting a needle valve on an engine. The air valves are also available separately so you can adopt it to an existing retract system by simply replacing the old with the new. The days of using wheel collars and air restricters to control the speed of the gear are a thing of the past, give one a try; I know you will like it.
The wing also features a preshaped leading edge and machine-cut wingtips which saves a lot of sanding and carving time. Once the two wing halves are constructed, they are joined together in the usual fashion via plywood dihedral braces before sheeting the wing. With most wing construction, it is common to wrap the center section with glass cloth after it has been sheeted. That is not the case here. First, the center section is sheeted then the entire wing is sheeted which produces a double sheeting over the center section. A unique way of taking care of the reinforcement of the center section. The wing is secured to the fuselage by two wing dowels in the back and two 1/4-20 bolts up front.
The fuselage is a tab-and-slot construction and is built inverted over the plan on a crutch. This ensures a straight and square unit. Once the bottom half is built, it is removed from the building board and the top formers are glued in place and balsa sheeting over them. The fuselage sides are 3/16" balsa with ply doublers. The fuselage formers have cutouts for the retractable tail wheel unit and air tank, as well as dimples or punch marks which show where to drill holes for the outer pushrod tubes and the pull-pull tail wheel steering cable.
I did encounter one problem with the front of the fuselage. The molded cut lines on the cowl do not match the plans. I followed the plans and came up short! I fixed this by adding some plastic to the back part of the cowl. So save yourself some headache time and follow the instructions (which say to make the cut at 7-7/8"), not the plans, for this step of the operation. Other than that, the fuselage builds to a very light but strong structure for its size.
I used Zap thick and thin CA's along with 5- and 30-minute Z-Poxy from Pacer Technology throughout the construction of this project.
As I had mentioned earlier, to build a plane like this and not to include retracts would be a crime. The choice of retracts was an easy task for two reasons: One, the plans are drawn showing Robart mechanisms for both main and tail units and I have used Robart units for years and have never been disappointed. If you have never flown a plane with shock absorbing struts, as you will find on the Robart gear, do yourself a favor and give it a try. They eliminate all the bumps and flopping that occurs with ridged gear on the take-off roll and also help to cushion the impact when you come in for a landing a little hard. Robart has just about any size and shape gear you would ever want. And, if you need something special, give them a call; special orders don't upset them. They also have an extensive line of scale hardware for your building needs.
I wanted my model to have drop tanks on the wings and be able to release them in flight. If you elect to do the same on any of your models, the mechanics should be thought out prior to building and sheeting the wing. This, of course, is to allow easy access to the inside of the wing structure. I also wanted the tanks, and hard points they hook on, to be as scale-looking as possible. I came across what I believe to be the perfect answer to my needs for the hard points - a company called Aerotech Models that manufactures a P-51 about the same size as Top Flite's and has a line of accessories to enhance the scale looks of the model. So I placed a call to them and ordered the scale options package which has the hard points, airscoops, gas caps, and a whole bunch of other goodies to trick out your model. The next task was to acquire a set of drop tanks. At this time, Top Flite does not have a set of tanks that fit the larger models like they do for their 1/7 scale models. But not a problem, a call to Frank Tiano Enterprises and the drop tanks were on the way. Along with drop tanks, FTE has bombs and dummy radial engine kits in a variety of sizes.
The entire model was covered with Top Flite's Aluminum MonoKote and the new Flat Olive Drab MonoKote. The checkerboard and invasion strips were painted on, using Top Flite LustreKote paint. The letters and numbers were cut from Top Flite MonoKote trim sheets. The Stars and Bars were from the mylar decals supplied with the kit. The kit contains all the decals necessary to duplicate the color scheme that is on the box art.
The engine used to power our Mustang was the U.S. Engines 4.2 gas, swinging a Top Flite 18 x 10 Power Point prop. The engine has a built-in spring starter that sure beats hand-flipping. I found the engine easy to start and performance was more than adequate to power a model of this size. The plans also feature this engine installation. A Du-Bro 24 oz. fuel tank was used to hold the go juice. A larger fuel tank would fit in the fuel compartment, but 24 oz. is more than ample a fuel supply for a gas engine in this plane. A Du-Bro Kwik-Fill fueling valve was also used for fueling and defueling.
A JR XP8103 radio was used to take care of the control duties. This is JR's 8-channel radio and has all the whistles and bells you could want. Eleven servos were used in this project and the big fuselage and wing swallowed them up with room to spare. Okay, you are asking, where are eleven servos used? Well I'll tell you - one each for throttle, tail wheel steering, bomb or drop tank release, retract valve, and rudder. Then, two each for ailerons, elevator and flaps. All servos for the flight controls were heavy duty, the others were standard. Having eleven servos working, I installed a 2800 mAh battery pack to power the on-board system.
With the Center of Gravity (C.G.) set at the stated 4-9/16" back from the leading edge of the wing and all controls set at the stated throws which are elevator high rate 9/16", low rate 3/8" for up and down. Rudder high rate 1-1/2", low rate 1" left and right, ailerons high rate 3/4" up and 5/8" down, low rate 1/2" up 3/8" down, and flaps are set at 7/8", and 2-1/8" in the down position. They also suggest to use 20% of exponential to the elevator to reduce the sensitivity around neutral. It is also noted that the control throws have been extensively tested and warn against using an extensive amount of throw, which could force a stall or snap roll. So take care, follow the instructions and after you become comfortable with your new aircraft, then make changes to fit your desires.
As they say, it's time to kick the tire and light the fire, Test Flight Time. With everything checked twice and engine pre-run and fueled up, air in the retract tank, there were no reasons not to put this bird into the air. The engine came to life with one flip, and I taxied out to the centerline. One last check of the flight controls and I started to push forward on the throttle stick while holding in some up elevator. The take-off roll was straight away with very little correction in steering. Still advancing the throttle and relaxing the elevator, the plane came up on its mains and at about 3/4 throttle and 300' down the runway she broke ground. I kept a shallow climb-out and started a gradual turn to port, still climbing to a safe altitude. Once there, I leveled out and put the wheels in the wells and started breathing again. After a dozen or so circuits around the field it was time to set up for landing. On the downwind leg and throttle at just below 1/2, I deployed gear and flaps. I was anticipating the nose to balloon up but nothing happened. The aircraft was stable all the way in to touch-down. Put all those myths away about P-51's being hard to handle, this one is a winner. After giving the airframe the once-over inside and out, the air and gas tanks were topped off and the bird was in the air once again, this time, more of a ring it out flight with loops and rolls; do what you want, it will handle it all. But, remember, this is a warbird not an Extra 300 - fly it like it should be flown. Make it realistic.
If you are an accomplished pilot on low-wing aircraft, you should have no problem flying this plane. And if you are comfortable in building a little more complex kit, you should be okay in this area as well. But note, this is not a beginner's kit to build or fly! It is also a big project that will take some time to do it right, which is the only way to fly! Oh, by the way, those low level passes at which time the drop tanks are released ... well let's just say I smile everytime I hit the release switch.
Reprinted with permission.
June, 1999 R/C Modeler Magazine
Editor: Dick Kidd