P-51 Mustang PTS – Part One

An interesting concept, this one. In the UK it’s quite common for pilots starting out in R/C to want to fly a Spitfire; travel ‘across the pond’ and tyro pilots in the USA would love to fly a P-51 Mustang from the outset. Traditionally such models have never been suitable for the beginner… until now! With careful design and a good dose of lateral thinking, Hangar 9 have addressed this conundrum with the introduction of their ‘Progressive Training System’ (PTS), throwing this concept at the USA’s favourite aircraft, the P-51 Mustang.

The PTS concept relies on changing the aerodynamics of the aircraft at different key stages in a pilot’s training to reflect his competency with a model. Initially the airframe is artificially dragged to force slower flight, the aerodynamics being progressively improved in tune with the students progression. This eventually turns the Mustang into a model with flight characteristics more in keeping with a semi-scale, low wing, W.W.II fighter. In theory this is a model that can take you from the ‘ab initio’ stage through the BMFA ‘A’ and ‘B’ certificates (assuming you manage to keep it in one piece, of course!). With undercarriage-mounted speed brakes, pre-positioned fixed flaps and quirky add-on NACA-sectioned wing droops to play about with, this was certainly going to make for an interesting test.

Think back to when you were taking your first tentative steps into R/C modelling. Had an option like this been available then, would you have chosen it over a standard trainer? I know I would have!

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In common with all Hangar 9s ARTFs the Mustang kit is well presented, and first impressions are that minimal work is required to complete the model. All the relevant parts are pre-covered in a tough iron-on film, which did show some signs of wrinkling straight out of the box. Hardware is typical of Hangar 9 kits – simple, but adequate. The wing halves are supported across the centre by a sturdy aluminium joining tube, but the whole lot can be glued together if you feel the need for a bit of extra security. Also, when assembled the completed empennage is fitted to the fuselage by means of two bolts, making it removable and so allowing the model to be stored and transported more easily, and with the possibility of less damage.

The undercarriage is a simple wire affair with rather over-large wheels on the main legs and a smattering of plastic parts to make up the remainder of the assembly. The 55-page instruction booklet is truly exceptional; very well illustrated with numerous good quality photographs to assist the first-time builder through the assembly process.

Control surfaces are all hinged with cyano ‘wick’ hinges, and with lots of pre-drilled holes and pre-installed captive nuts the model went together really quite easily. The general assembly of the airframe is pretty much as per your typical ARTF, so I won’t detail the whole process, however I did hit a few snags along the way that are worthy of mention.

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The first issue I came across concerned the elevator horn, which had to be moved from the position suggested in the instructions so as to avoid the elevator joiner. Also, when fitting the fin and rudder assembly to the fuselage, I was unable to find the pre-drilled hole for the fin strake locating dowel. The covering film is double thickness in this area, but no amount of prodding or film lifting would reveal the location of the accursed hole. This being the case I had to assume that it wasn’t there so I centralised the fin, marked the dowel location and drilled a new one.

Wing assembly is pretty straightforward, but the extension cables for the individual aileron servos are a little fiddly to feed through the formers as there are no handy pull-through strings installed. The aileron servos require mounts to be added to the wing, although when test-fitting these I found that the servo mounting nearest the t.e. on the port wing was distorting the film on the upper surface of the panel; a situation that became worse when I fitted the servos as I could clearly see the profile of each servo pressing on the wing covering. That said, the instructions recommend using JR 537 servos and I was trying to fit Futaba 3003s, which are slightly deeper. To avoid unsightly wear on the upper film surface I simply packed the rear edge of the servo off the mount with a couple of small washers fixed with epoxy. This was a shame, because the servo mounts were a fantastic fit.

When I came to install the locating dowels to the wing l.e. I found that the pre-drilled holes were about 6.5mm diameter, but the dowels were 8mm… a bit of careful re-drilling soon had that sorted, though. The good news is that the throttle, rudder and elevator servos fitted into the pre-formed servo tray in the fuselage without any problems. In fact fitting the radio gear was a breeze. The only niggle in this respect concerned the routing of the receiver aerial, which has to be fed through a rather small tube inside the fuselage. With my well-used Rx having a very flexible aerial it was like pushing a wet flannel up the high street with a coat hanger! I remedied this by blowing a length of cotton through the tube, which was duly attached to the end of the aerial before being pulled back through. In the interest of a fair review I tried it as the manual suggested, but Im afraid the process turned the air blue somewhat. Since this is a family website, my comments shall remain undisclosed!

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A plywood former that holds the Rx and battery in place also supports the fuel tank, and is really well thought out. The wheels supplied with the kit are hugely out of proportion at 90mm diameter, but they do form an integral part of the ‘easy handling’ concept of the model. The snap-on wheel trims are a nice touch too, but the hole in the wheel and the diameter of the wire landing leg didn’t match; the wheel had to be drilled out to the required size.

With the bulk of the work done, the last major task was to fit the engine and cowling. The kit is designed around the Evolution 40TP motor which, like the model, is specifically designed with the first-time user in mind. The engine has anti-tamper stops on both needle assemblies, spins a 3-bladed propeller and has an additional flywheel to aid a reliable idle; in practice it all works very well indeed.

Installing the engine was a simple task as the supplied mount fitted the pre-located captive nuts on the plywood firewall perfectly. The difficult part was fitting the cowl; the manual shows and explains this in depth so there’s no point my going into great detail, but I do advise you to take your time marking out, and take the minimum cuts from the cowl. Remember that you can always make the aperture bigger, but never smaller! One thing I did notice was that with the flywheel in place it was nigh-on impossible to remove the cowling.

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So that was it! With only the odd decal to fit (most are factory applied) and the canopy to attach, the model was complete and ready to fly. With all the control surface throws set as specified in the manual and the aircraft balance as required (no additional weight was needed), it was time to take this new concept out on a date! In Part Two, I’ll let you in on how she handled…

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