World Models P-51D Mustang

World Models P-51D Mustang

 

  • This review was first published in RCM&E November 2005 and the kit is still available (see link below).

I like Mustangs. In fact I’ve owned three such ARTFs over the last few years, two of which I’ve managed to ‘total’ in dodgy circumstances. I therefore came to this particular review with both excitement and a certain amount of trepidation. But I needn’t have worried as World Models’ Mustang, complete with retracts and flaps out of the box, flies like a pussy cat.

BOOT BOY
This Mustang is a good size, big enough to be impressive and yet small enough to fit in the boot of most cars. World Models have a good reputation and this kit is firmly amongst the best in terms of quality – very complete and with clear, well-presented pictorial instructions (this machine isn’t aimed at beginners, so these instructions are completely adequate). Assembly time is short since the wings, tail feathers and fuselage are (of course) supplied ready-built and covered.
There was a petite problemette in that these days we’ve become habituated to practically faultless covering on our ARTFs and yet, around the fin area, my example looked a bit rushed. Nothing horrendous and not enough to prompt me to recover the joins or complain, but all the same it was a bit below par for a model in this bracket. The supplied fibreglass cowl, complete with dummy exhaust stacks, is a very good sport-scale item, as is the large matching spinner (also supplied). The icing on the cake is the inclusion of a second, see-through cowl to assist you when cowl bashing; you do all your marking out on this without touching the real one until you’re ready – a truly splendid idea!

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ENGINE PICKING
Since engine fitment and cowl bashing form major elements of most ARTF builds, it pays to consider your choice of engine before beginning. This is doubly true with a near-scale fighter like this one, where you want effortless performance and, if at all possible, a sympathetic engine noise.
Bearing this in mind, I elected to fit a sexy new RCV .91 four-stoke. I reckoned using this fascinating power plant meant I could kill three birds with one stone by:

● Avoiding the need to cut a big ugly hole for the cylinder head – the RCV is very compact.
● Reducing the amount of subsidiary cowl bashing required by keeping the ancillaries like carb’ projections inside the cowl.
● Enhancing flight realism with the RCV’s distinctive four-stoke sound.

NON-BASHED COWL
Initial trial fits and measurements were extremely encouraging. They showed that the RCV would fit the supplied engine mount provided I dropped the World Models rubber quiet mounts, which are intended to sandwich between the engine and the mount. I quickly realised that the entire RCV would be swallowed up by the cowl, with only simple holes for the exhaust and needle valve being required. I couldn’t believe my luck.

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RADIO & RETRACTS
To add to the ‘bling’ factor, this model comes complete with flaps and pre-installed retracts. The retracts are the usual ARTF fare, plastic bodied with spindly legs. Whilst probably adequate for immaculate tarmac, I divined that they might not have a long and trouble-free life on the standard club grass field. It’s funny that most ARTF manufacturers seem to be oblivious to the real-world situation in this regard. I decided to use a dedicated retract servo in the wing and ordinary servos for the rest of the installation. Getting the pre-fitted retract wire pushrods to mate with the servo was a bit of pain, since the finger space in the wing aperture is necessarily limited. It’s not possible to see the entire route taken by the retract pushrods since the moulded wheel wells and lower wing surface are in the way. This meant that I couldn’t be quite sure if the pushrod was bowing too much as it attempted to lock the wheels down. At first I felt that I must have got the geometry wrong somewhere because whilst the undercart would retract, it wouldn’t lock reliably on both legs. From experience I know that this usually just means the ‘pushing to lock’ impetus from the servo hasn’t travelled far enough. I persevered and eventually got it to work upside-down on the bench.

My usual addition of a combined radio on / off / charge switch completed the installation. This allows a quick battery check before each flight; doubly important with a model that has electric retracts, which can consume large amounts of power if they’re binding or jamming. Incidentally, throughout the build I used all the supplied fittings and hardware and all were fit for purpose. Oh, and fitting the pre-made control surface pushrods was a doddle.

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FINISHING OFF
The fibreglass belly pan moulding is a well-made item, though it doesn’t have the scale intake and has to be removed every time you re-fit the wing. It’s slightly fiddly to re-fit each time and, frankly, it could have been better thought out. However, despite the rather un-scale (and somewhat toy-like) shiny silver film finish, I must admit she does look an absolute peach. Maybe the World Models designers were going after a post-war pampered Reno Racer effect. But such was my Mustang’s overall allure, all my mates down the patch commented on how attractive the model looked.

TEETHING TROUBLES
The allotted day for the maiden flight finally rolled around, with bright sunshine and balmy winds. As usual I convinced long-suffering mate Gareth Williams to do the initial honours whilst I took the flying shots.

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The first job was to stoke up the new RCV. The CD .91 is almost entirely conventional from the outside and can be started in the ‘normal’ way. It was only then I realised that I couldn’t access the cowled-in carb’ for a quick prime, so I choked off the exhaust outlet with my thumb and tugged the prop’ over three times to pull some fuel through. Applying the glow start to the external glow connector I was rather surprised to see it promptly spring straight off. The remote glow connector didn’t match either of my two glow starts – something I hadn’t anticipated in the shed. Fortunately, a flying mate, eager to see the engine start, gave me a different design of glow start, which worked. Try again.
Setting to 1/3 throttle, I applied my tiny Marx epicyclic electric starter to that massive scale spinner, and the RCV turned over very sweetly. The engine gently started and picked up; on opening the throttle it didn’t fade, but it was clearly just a little too rich on the guessed setting of 21/2 turns. I leaned her out a trifle and she ran just fine, throttling beautifully.

LIFT OFF
At the patch all appeared fine, and we set the Mustang on her wheels ready for take-off. Gareth throttled up and she pulled forward – then promptly sagged and fell on her nose. The port leg had auto-retracted – what a disappointment! It wasn’t locking down, even though it had worked on the bench many times. I then spent a fraught fifteen minutes attempting to tweak it, but in the continued absence of a reliable cycle I decided to lock it down for the photo flights.
Leaning out the RCV a little more, clocking a respectable 8,400 revs on a 14 x 8” prop’, the Mustang was given a girly shove to overcome the initial resistance of the grass. Gareth held in full up elevator to keep the tail down until she was running down the strip, then eased it off until she reached take-off speed, re-applying just a touch until there was daylight under her wheels. She immediately looked completely right in the air – absolutely rock steady and flying effortlessly… very confidence inspiring. All the petty teething problems with the retracts melted into insignificance. It was one of those “Cor!” moments. Then there was the engine note… the sound of a model engine is a very subjective thing, but I thought she sounded absolutely great – a bit gravelly at the lower end, yet clean and four-strokey at the top end; very sympathetic for a fast W.W.II monoplane fighter. The RCV proved perfect for this Mustang, flying it with authority and supplying appropriate power for aerobatics and beat-ups, yet not screaming away like a two-stroke.

On subsequent flights that afternoon the engine / model combination proved itself to be ideal. Gareth reported it to be very well behaved and the glide and low-speed handling were faultless. High praise indeed! As he chucked her about in mock combat, she really did look the part. When I was a nipper I dreamed of radio controlling scale W.W.II fighters, and here was full Technicolor wish-fulfilment.

GIMME GIMME!
With the pictures safely in the can, I had the opportunity to get behind the sticks and gain my own impressions. Now, anything over a .60 is ‘big’ in my book, so I’m delighted to report that the RCV and I are getting on rather well; this superb engine is totally unfussy, uncritical and always starts first time. It’s proved to be very tractable and well behaved, and I love it to bits. The bottom end ‘grockle and pop’ is a bit busy at very low throttle settings, but I quite like that. Starting is a dream, a gentle spool up every time with no kicking back, no lock-ups, no false starts and no fades. The second needle remains untouched. All you have to remember, as with all other engines, is not to run it too lean. I suppose I could experiment with different props, but there’s really no point when the current match to the airframe is so pleasant.
Anyhow, about to take off, I remembered to hold on full up and opened the throttle briskly. With a slight shove she zapped down the strip, lifted off, and then flew completely predictably. Within a half circuit I was relaxing and enjoying the view. I adore long, low passes and beat-ups and she looks just superb when flashing by. All club aerobatics are performed easily and with the RCV you can coax her to do big fighter-type loops. Truthfully, just flying her hither and yonder is a complete tonic. I should have had one of these thingies years ago!

SUMMARY
I’ve since sorted out the retracts and got reliable lock-downs; the fitted pushrod wire was just too bendy. Also, to be fair, unless I’ve intervened smartly with the elevator, every ARTF Mustang I’ve flown thus far has had a tendency to peck when taking off and landing, so this one is no exception. Flying from tarmac might indeed be easier. Unfortunately you can’t tweak the sprung undercarriage legs forward as you would with a sports model because then the wheels wouldn’t retract into the wheel wells. So, I’ll just have to get my take-offs and landings right every time, won’t I?
What about value for money? Well, I can wholeheartedly recommend the Mustang as a flyer, and although clearly sport-scale, to my eyes she looks just smashing in the air. You have all the toys to play with, too, like flaps and retracts. She has no obvious vices and won’t bite you on slow, low turns. The good news is that the price has recently been reduced from £229 to £199, making her even more of a bargain. The complete package of this Mustang / RCV .91 is a marriage made in heaven, with the added advantage of minimal cowl bashing. So, if you’re in the market for a Mustang of this useful size, I would genuinely recommend looking at the World Models version first. She really is a first rate flying machine, and a good-looker to boot. Every time you fly her past on a beat-up you’ll find yourself shouting, “Dagga! Dagga! Dagga!”

DATAFILE
Name: P-51 Mustang 60
Model type: Sport-scale ARTF warbird
Manufactured by: World Models
UK distributor: Steve Webb Models
RRP: £212.39 (Dec 2010)
Wingspan: 64.5'' (1639mm)
Wing area: 5.2sq. ft. (0.48sq. m)
All-up weight: 8.5 lbs (3.8kg)
Wing loading: 26oz / sq. ft. (7.9kg / sq. m)
Control functions: Aileron, elevator, rudder, throttle, flaps, retracts
Rec’d engine: .60cu. in. two-stroke,

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