VQ MODELS P-51B MUSTANG – Part 1

VQ MODELS P-51B MUSTANG – Part 1

Andy Sephton assembles a razorback Mustang from VQ Models growing warbird fleet.

When our friendly Editor asked if I would review a scale model for RCM&E, I jumped at the chance. I’m currently promoting the Light Scale Class for Scale competition in the BMFA and such a project would sit very nicely within the promotion.

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Andy with the completed P-51B.

I’m aiming to encourage club scale flyers to have a go at BMFA scale competition and a model such as the VQ Models P-51B Mustang would be an ideal subject. At the moment Light Scale is a flying only competition flown to standard BMFA Rules, except that the model weight is limited to 5Kg.

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I wonder what it will look like in flight. Pretty good, I should think!

However, in order to get the report on the streets it’ll be presented in two parts. This, the first one, will be on the model build to flight standard; the second will be on the test and demonstration flights.

FIRST APPEARANCES

The model arrived in good condition; it being well packed inside a substantial cardboard box. All of the parts were wrapped in polythene and taped to the side or bottom of the box to prevent movement.

The package included: the basic airframe with pilot already fitted, a fixed undercarriage, wheels, engine mounts, a tank, spinner, fibreglass cowl, screws, hinges, links and horns, a decal sheet and a booklet of instructions.

One nice touch and, as a hands-on modeller, one that I really appreciate was that the pack included several sheets of coloured vinyl that could be used to repair tears and holes in the model’s covering when it becomes necessary.

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The first layer upon opening the lid.

There are four alternate colour schemes for the model – VQA05 ‘Tuskegee’, VQA06 ‘Shangri-la’, VQA06B ‘Boise Bee’ and VQA06BEX ‘Berlin Express’. Although the box was labelled ‘Boise Bee’, the decals supplied were for the ‘Berlin Express’, so that will be the finished scheme for this model.

The instructions say that to complete the model the modeller would need to provide a minimum of a suitable power plant (ESC and motor or IC engine), a LiPo or suitable Receiver battery, a propeller, at least four servos (electric power) or five servos (IC power) and a suitable receiver. In addition, cyanoacrylate and epoxy adhesives are required and a set of basic modelling tools. The instructions suggest the following for the latter: hobby knife, needle nosed flyers, sander, Phillips screwdriver (the wing bolts, however, have slotted heads!), scissors, hex wrench, awl (I call this a hole-boring tool), wire cutters, masking tape, straight-edged ruler, pen or pencil, rubbing alcohol and, finally, a drill with assorted bits.

I opted for electric power, so on advice from MacGregor Industries, the distributors, a MacGregor Electrospeed 5055/06 brushless motor was acquired, together with a MacGregor Electrospeed 80A XP2 brushless ESC.

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Contents of the VQ Electric Retract set. Note that the UC leg is set just off a right angle to the housing, which allows the UC leg to sit at the correct angle to the wing. The disadvantage is that on retraction the UC retracts about 5 degrees too far into the wing bay (see text).

As the model is destined for BMFA Scale competition, I opted to fit a retractable undercarriage and a VQ-ARE03 electric retract set for the P-51B was also procured from MacGregor. Again, for competition use, I opted to use working flaps, so an extra two servos were required, in this case the MacGregor MG1703DS Midi Servo. Four MacGregor MG5510DG standard servos were used for the remaining services.

To complete the package, I ordered several Master Airscrew 14” x 6” electric propellers and several 4S 4000mAh LiPo power packs.

For information, the recommended IC motor is a 0.46 two stroke or a 0.70 four stroke.

ASSEMBLY

Assembly of the model was relatively straightforward. It went together pretty quickly, in the manner of most ARTFs. There were no major issues, but it’s worth noting areas that progressed easier than I expected and those that required a bit of modelling skill, rather than just fit-and-forget.

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Setting up the flap servo using a servo tester. Note the excess length of the control rod, which was later cut to size. All control rods in the kit were of an equally generous length.

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Undercarriage in the up position with the leg hard up against the inside of the U/C bay.

The instructions were excellent. The standard of English raised a few smiles, but in the main they were fully understandable. The diagrams were good, and the order well thought out. The only issue I found was to do with the electric motor mount. The distance described in the instructions between the firewall and the drive-plate of the electric motor was too small. In order for the propellor to clear the supplied cowl I had to increase the distance by 5mm, from 115mm to 120mm. It’s a small point but if not taken into account the propeller will foul on the cowling.

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Sanding the wing joiner down to size on a belt sander.

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Joining the wings using the rather elegant method of rubber bands on the wing bolts and a bulldog clip on the split wing tongue. Note the servo wires being held out of the way of the epoxy with masking tape!

Also, the designed position of the motor mounting holes, together with the built in down and side thrust, caused the propeller shaft to exit the cowl off centre. I got around this by altering the length of the engine plate mounting screws to bring the shaft into the centre of the cowl. This will, of course, reduce the down and side thrust, but I felt that this was a small price to pay for getting the model to look right.

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This is how the motor exited the cowl with the mount parallel with the firewall.

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Motor mount fix.

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The motor shaft now exits at the centre of the cowl.

RETRACTS

Fitting the electronic retracts proved to be a bit more complex than I’d first imagined. Owing to the dihedral the angle between the wing axis and the extended undercarriage is less than 90 degrees. The retracts supplied were a 90-degree system, so they moved further than required on retraction. This is not a problem in practice, once it has been identified, but it did lead me to fit the undercarriage with the wheels ‘on the outside’ rather than with the wheels ‘on the inside’ as per the full size.

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Retracts being checked in the up position, with the radiator and wing fairings taped in place while the adhesive sets.

The slope of the wing surface prevents full retraction of the wheels with them ‘on the inside’ as the tyres foul the upper wing surface. The axle keeps the tyres clear of the wing surface when the wheels are ‘on the outside’.

The other challenge I had with fitting the undercarriage was that the heads of the supplied screws kept distorting. They were replaced and the problem was solved. It is worth noting that a significant part of the plastic undercarriage insert had to be cut away to allow the retracts a clear path into the wing. This was easily done with a sharp modelling knife.

PARTS FIT

The fit of the parts was generally tight. Most had to be eased a bit to allow assembly of the model. This, of course, is preferable to the fit being too loose! Most of the servo holes had to be enlarged slightly to allow the servos to fit.

This was easily achieved using a steel ruler as a guide for my modelling knife. However, in the case of the wing joiner, I had to resort to the use of a belt sander to reduce it to a thickness that would allow it to slide into the slots in the wings.

On the other hand, I was really impressed with the hint to use rubber bands on the wing bolts to hold the wing halves together while the epoxy was drying. I’d never thought of doing that before; it’s an elegant way of holding the two wing halves together and it works! The design of the front wing tongue was also impressive. Made in two halves, one on each wing, that too could be used to hold the wing halves together as the epoxy dried.

The instructions advise cyano to fit the air intake and fairing under the wing. It worked with the latter, but the air intake required something a bit more substantial. I eventually reverted to epoxy, which has proved to be successful, so far…

MOTOR TEST

There is one issue to report, in that when I carried out the motor tests, there was an associated heavy vibration. I traced it to the spinner in the kit being out of balance. I’ve since replaced it with one of my own but of a different colour – yellow rather than red. The engine run is now smooth.

SUMMARY SO FAR

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The completed model really looks the part.

So, after a few hours work and a few days drying time in-between, I now have a rather nice-looking P-51B. With an FrSky Fr6x receiver fitted and a 4000 mAh 4S LiPo fitted to the rear of the bay, just in front of the pilot, the C of G comes out in the recommended position with an all up weight measured at 3,412 grams.

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Undercarriage check before the first flight. Flicking the gear switch has them sitting neatly inside the wing.

The control throws have been set up as per instructions, so we are now all ready for the first flights and a photo session.

DATAFILE

Name: P-51B Mustang ‘Berlin Express’
Model Type: WWII warbird
Manufactured by: VQ Models
Distributed by: MacGregor Industries
www.macgregor.co.uk/vqmodel/vqa06bex.htm
RRP: Options start at £199.95
Wingspan: 60in (1524mm)
Length: 46.8in (1189mm)
Weight: 2.72 – 2.94kg (6 – 6.5lbs)
Power system: Electrospeed Boost 60 Power Pack

Functions (servos): Ailerons (2), rudder (1), elevator (1), throttle (1 or ESC)