| P – 51D MUSTANG | 0202 |
Congratulations on purchasing this scale model, depicting the North American P-51D Mustang, a WW 2 fighter.
The actual aeroplane, considered by many to be the most successful WW 2 fighter, was created based on specification issued by the British Air Ministry. When in January 1940 the British purchasing commission in the USA sought with the North American Aviation company a help with the licence manufacture of the P-40 Tomahawk fighters, they were offered in turn a company's own project, promising much better performance. The NA-73X prototype airframe was finished by this company, until then producing mostly various training aircraft, in a record time of 127 days, standing ready for its engine on 9th September 1940. After waiting a score of days, the Allison V-1710F-3R was delivered and installed. The NA-73X prototype took off for the first time on 26th October 1940. The series machines, differing considerably from it, were armed with two 0.5in (12,7mm) machine guns in the fuselage and a 0.3 in (7,62mm) machine gun in each wing, were designated Mustang Mk. I, and introduced to the RAF service in spring of 1942. The new aeroplane aroused interest of the US Army Air Force, who put it to service as the P-51A. The attack/dive bomber version, fitted with a pair of bomb racks under the wings and with dive brakes, was designated the A-36A Apache.
The P-51B/C versions (British designation Mustang Mk. III) were fitted with the Packard V-1650-3 Merlin engines (built under licence from Rolls Royce). Their armament consisted of two pairs of 0.5in machine guns in wings. They were the fastest series-built Merlin-powered versions. The P-51D/K (Mustang Mk. IV) version was the most numerous variant of the famous fighter, the first to be fitted with the cut-down rear fuselage and the all-round vision (bubble) canopy. The armament was increased to six machine guns. The last series-built version of the Mustang was the lightened P-51H with the Allison engine, noteworthy by its taller vertical tail and a wing without the wing root leading edge extension. Altogether 15 500 Mustangs were produced, of this number 9600 were of the P-51D/K version. Many machines served around the world quite long after the war, and they can be met not only in museums, but also at the air shows and air races.
The prototype for the colour scheme and marking of your scale model of the P-51D is the machine serving with the 361st Fighter Group of the US 8th Air Force at the Bottisham air base , UK, and, in late 1944, at St. Dizier airfield, France.
The model is not suited for complete beginners, but its control with ailerons and elevator would not bring problems to any modeller experienced enough with elevator/rudder control models, e.g. slow-flyers. The flying qualities of this model of the P-51D Mustang are close to that of much larger model, i.e. they are more docile, and provide fine as well as colourful experience in the air.
The model kit you have bought has several noteworthy features:
- It is almost finished, you only have to apply decals, install the propulsion unit and the RC equipment. You can utilise the kit's box as the transport and storage container for finished model.
- The model is moulded from extruded polystyrene foam (EPSF) with harder surface layer, making the model more resistant to surface damage. All exposed spots are reinforced with plastic covers. Thanks to the ratio of the all-up weight of the model and of the strength of the material the model is quite compact, this making the danger of damage in normal operation very low.
- When designing this model a maximum attention was devoted to its aerodynamic layout (e.g. the semi-symmetrical wing section, the symmetrical horizontal tail section), ensuring high aerodynamic finesse, with the resulting wide band of operational speeds and docile flying characteristics typical for large models.
- The range of proven power units offered enables to build a scale model of flight performance corresponding with that of the best slow flyers, as well as with the fully aerobatic models.
- When choosing the battery, check please not only the nominal voltage, but also the available current drain (NiMH, LiPol).
- To control the model you need the RC equipment suitable for controlling the slow-flyers - it would enable you to fly majority of the aerobatic figures (with the possible exception of those that require the rudder control).
- One of the decisive factors, affecting the flight performance and behaviour of the model, is its weight. The weight of the model without the battery pack should not exceed 320 grams. With a double-cell LiPol battery would probably weigh in at 380 grams, with the six-cell 500mAh NiCd pack about 420 grams. The specified maximum weight should in no case be exceeded - the flight behaviour of heavier models deteriorates accordingly.
It is a simple task, yet we ask you to read and follow the subsequent text thoroughly.
The decals
The model is sprayed with colours making up its basic camouflage scheme. The codes and markings consist of the waterslide decals. Their primary advantage is the negligible weight and a minimum risk of damaging the model during application. They require, however, an attention and care. Therefore we recommend that you follow the subsequent instructions:
- The larger decals that are to fit to a double-curvature surface need to be cut radially at several places around the circumference .
- Dip the decal cut-out from the sheet with its backing paper into a lukewarm water for about 5 seconds, then leave it to soak through on a flat non-absorbent surface (glass plate, plastic sheet etc.).
- You may increase the adhesion of the dried decal to model substantially by applying wallpaper glue to the area where the decal will be placed. However, ensure in advance that the glue would not create blotches or lumps when it dries - this is why the white (PVA) glues are usually not suitable.
- Once the backing paper is sufficiently soaked (i.e. the decal moves easily on its backing paper), slide the decal over the edge of the backing paper about 5 mm, keep it with your finger in required place on the part to be decorated and pull the paper from beneath the decal. If the decal does not slide easily enough, apply some more water around it with a paintbrush; it will help you to replace the wrongly-applied decal, too.
- Using a soft cloth or, rather a polyurethane foam roller, carefully smooth out the decal, gently squeezing the excess glue and any air bubbles from the centre to its outer edge. Do not squeeze out all of the glue! Once the glue dries, i.e. in a few hours, the decals would shrink somewhat and adhere snugly to the surface.
- To increase the adhesion of the decals, you may use a decal setting solution, available for plastic scale modelling. Check that solution does not attack the styrofoam and follow the directions for its use.
- The model could be oversprayed with a thin layer of transparent gloss or semi-matte (avoid spraying the transparent cockpit canopy) acrylic or synthetic varnish to suit your ideas regarding the surface finish of the real aeroplane. It is absolutely necessary to check that the varnish does not attack the polystyrene foam. To keep the weight down, spray varnish very sparingly.
A) RC equipment
The schematics of the circuitry and the placement of the system's individual components is shown on the drawing. We strongly suggest that you assemble and connect the RC equipment outside the model and check its function. Observe the recommendations of manufacturers as listed in the directions of use for the respective components. Check the compatibility of the receiver with the crystal used - the over-the-land range test of the transmitter, albeit it may seem unnecessary nowadays, may save you much much more than it would cost…
B) Power unit (motors with the MP Jet gearbox or MP Jet outrunner 28/7…)
C) Aileron control
The aileron servo should be powerful enough to overcome the friction in the control bowdens - we recommend to utilise a servo of more than the 0,15 Nm minimum torque. The friction in the bowdens could be reduced by removing the push-pull rods from the tubes and lubricating them with a thin oil, such as the WD-40.
- Place the connector 10 into hole in the servo single arm, at the distance of about 11 mm from the axis of servo arm rotation. If the openings in the servo arm are too large, it is better to drill new ones of 1 mm diameter rather than bushing-out the old ones.
- Insert a 6mm long piece of the tube 11 into the connector opening.
- Insert the control rods to the connector, first one, then the other (fig. C1).
- Insert the servo into the wing opening and place it so that once the servo arm is inserted on its shaft (the axis of the servo arm should be parallel with the longitudinal axis of the servo) the control rods are well aligned and that the set-screw 12 could be tightened (fig. C2). If the wing opening is too small for the servo, modify it. It should fit tightly; the best way is to cut the opening somewhat narrower than the servo width and then to push the servo in carefully. If need be, you may enlarge the wing opening even in front of the servo, but always take utmost care when cutting into the hard surface of the plastic.
- Devote maximum attention to the correct positioning of the servo - only that way you would ensure the proper function of the controls. Secure the servo against movement by applying a thin layer of PU glue or Epoxy around the perimeter of the wing opening - in case a servo needs to be removed it is easy to pry it free without damage.
- Tighten lightly the screw 12 so that the aileron trailing edges would be some 1,5 to 2,0 millimetres above the wing trailing edge (fig. C3).
- Check function of ailerons: they should be at the maximum deflection of about 10 mm at the maximum deflection of the control stick - check the correct sense of their deflection! If they are not moving correctly, and you could not program the servo throw by the RC set programming, change as necessary either the position of the control rods in the control circuit arms or of the connector on the servo arm. Only then secure the connector against becoming unconnected by the spring washer 13 inserted from below (the servo arm is outside the model, using a thin tube such as the ball point pen refill), and then secure the servo arm itself by the screw 14. Readjust the correct position of the ailerons and tighten the screw 12. Secure the control rods against disconnecting from the control arm by gluing a piece of tubing onto it (fig. C4).
- You can secure the connector gluing a piece of tubing instead of spring washer 13. If the tube is glued well, this simple method works very well, in case the disassembly would be needed the tube would be simply cut away.
D) Elevator controls, accumulator pack placement
A servo of more than 0,07 Nm minimum torque is recommended for the elevator control. Both moving surfaces are interconnected by a glued-in coupler. If one of the elevator halves deflects excessively (outside of the recommended angles), the coupler may become loose and the deflections (especially the maximum ones), may differ substantially. Restore their stiffness by gluing (Epoxy) a "U"-shaped connector made of steel wire of 1,5 mm diameter.
- Check that the opening in the servo base plate 15 corresponds to the size of the servo you want to use, enlarge the opening if necessary.
- Sand the elevator push-pull rod support 16 to the width of 50 mm and glue together with the servo base plate 15. Insert the assembly to fuselage so that it would rest on the longitudinal stiffeners as per fig. D1.
- The position of the base plate at the fig. D1 is a general suggestion. Its exact position has to be found once the preliminary rough balancing of the model, using the RC equipment elements and batteries, is done - see E).
- Glue the correctly positioned base plate to the stiffeners and fuselage, using PU or epoxy glue.
- Insert the servo into the base plate from below (so that the servo shaft end of the servo would be forward, i.e. farther form the elevator control rod support) and secure it by gluing with PU or epoxy glue, or by screws.
- Insert the connector 10 to the hole in the servo arm that is placed about 8 mm from the axis of the servo output shaft. Drill a new hole if needed. Insert about 6 mm-long piece of the plastic tubing 17 into the connector hole. Insert the assembly to the elevator control rod and insert the servo arm to the servo output shaft so that the arm's axis would be roughly perpendicular to the elevator control rod axis (fig. D2). Glue the control rod tube to the support 16 (PU, Epoxy).
- Tighten slightly the connector screw 12 - the servo arm and the elevator control are both in neutral position.
- Check that the maximum throw of the servos corresponds to the maximum elevator deflection of about 10 millimetres (fig. D3). Note! Ensure the sense of aileron deflection corresponds to the control stick movement! If they are not moving correctly, and you could not program the servo throw by the RC set programming, change as necessary either the position of the control rod in the control arm or of the connector on the servo arm. Only then secure the connector against becoming unconnected by the spring washer 13 inserted from below (the servo arm is outside the model, using a thin tube such as the ball point pen refill), and then secure the servo arm itself by the screw 18. Readjust the correct position of the elevator and tighten the screw 12.
- Secure the control rod against disconnecting from the control arm by gluing a piece of tubing onto it (fig. D4).
Accumulators are attached to the base plate using a self-adhesive Velcro strip. If you do not feel safe using this method, you may secure them with some additional rubber bands atop of it.
The receiver is attached to the underside of the base plate also with a self-adhesive Velcro strip. The receiver antenna may be lead out through the fuselage belly and either attached with an adhesive tape to it or left freely streaming behind. It is recommended to check with the motor running (especially at the maximum power) that no interference (jamming) of the RC receiver takes place - it would manifest itself by oscillating of servos. In that case move the receiver to the fuselage sidewall forward or even better rearward of the cockpit.
To facilitate the transport and storage of the model the wing is made detachable. To assemble the model, insert the wing, trailing edge first, into the cut-out above the belly radiator scoop, then secure the wing in the fuselage, using the bolt 19 - tighten carefully! Reverse the process to disassemble the model.
If you want to fit the pilot into the cockpit, you have to carefully remove the cockpit canopy (it is tack-glued), place and glue an assembled and painted pilot in and glue the canopy back in place.
E) Flying the model
Balance the complete assembled model by shifting the position of battery pack along the base plate. The prescribed position of the CG is marked on the wing bottom surface by transverse lines on the undercarriage doors (fig. E). Balance the model on your fingers, as sharp items may damage the styrene surface. The model should remain in a level position or slightly nose-down. For the first flights the centre of gravity may be moved some 5 millimetres forward, but absolutely no rearward shift of the centre of gravity would be allowed! Mark the correct position of the battery pack on the base plate (it is best done at leisure at home), and check there also the RC equipment, i. e. the sense and magnitude of deflection (throw) of the ailerons and elevator and the operation of the controller.
First, glide - launch the model over higher grass to cushion its eventual falls and check its reaction to controls. If you can, set the non-linearity on the transmitter to 50 % both for ailerons and elevator. The powered flight will differ according to the power unit - the "280" will make the start just a bit more lively than with a slow-flyer, the AC motor will try to jerk the model from your hand - be ready for a pronounced torque from the propeller in slow flight when the controls are less effective.
Once the model is trimmed in the powered flight, try the marginal regimes - especially the slow flight and stall behaviour of the model. Once you become accustomed to the model, you may return the ailerons to normal zero setting.
You will soon find that if you want to fly the well adjusted Mustang, you need not to wait for a calm weather. The model handles well and has a broad range of speeds, behaving like a much larger aeroplane. It will be only up to you if you feel like going out to fly the P-51D.
We wish you many happy landings.
Alfa Model Ltd.
A list of parts and tools necessary for finishing the model that are not supplied in the kit:
- Polyurethane (PU), five-minute Epoxy glue, cyanoacrylate glue.
- Modelling knife, screwdrivers, transparent self-adhesive tape, 1mm drill bit.
- Power unit with controller and propeller, battery pack etc.; some of the tested recommended combinations are listed below.
- At least a three-channel RC set with two micro servos (up to 10 g weight) and a miniature receiver (up to 10 g weight).
- Extension cable (150 mm) to attach the aileron servo to the receiver.
- Battery charger.
