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ZK-TMG test and display pilot Bryan Gault shares his experience with a report on what it is like to fly this unique ultra-high performance aircraft.

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It was April 3^rd 1955 as a 20 year old with just over 200 hours total flying time that I first flew the P51D.  RNZAF wings graduation had been some three months earlier in December 1954 and whilst waiting for a flying instructor course I had the great good fortune to be temporarily posted to No. 3 Territorial Squadron.

The legendary Mike Daniell was 3 Squadron Adjutant and it was he who converted me to the P51.  Circuit and landing training in the back seat of a Harvard along with detailed briefings on handling and study of the pilot’s notes constituted the conversion.  The first flight was memorable for the distance behind the aircraft I remained throughout the short sortee, nothing that the Harvard can produce prepares one for the brute force of the P51 on take-off.

I waited almost exactly 50 years to experience again that sensation of raw power, this time in the Thunder Mustang, the three quarter scale replica of the original P51.  My son Simon, an avid aviation enthusiast and and pilot of considerable ability, first saw the Thunder Mustang at Oshkosh .  On his return to New Zealand he asked me what I thought of the idea of forming a syndicate of like minded enthusiasts with the intention of purchasing a Thunder Mustang.  His intention was that I should undertake the test flying programme on behalf of the syndicate.  I felt the odds of the syndicate finding one of the less than 7 or 8 flying Mustangs for sale was about as likely as Helen Clark reforming the air force strike wing, so I agreed.

My underestimation of Simon’s determination is a mistake I have made repeatedly over the years and with a tip-off from Warren Denholm of Avspecs, a suitable aircraft, ready to fly was found in South Africa .  After two years of negotiation the deal was done and the syndicate had their Thunder Mustang with only two hours total flight time.

Suddenly my role as test pilot became a reality and with a short break of just 50 years I found myself wondering how far behind the aircraft I would be this time round.  The performance of the Thunder Mustang is nothing short of phenomenal particularly during take-off and climb.  The Ryan Falconer V12 delivers 640 h.p. and with a power to weight ratio of just 4.69lbs/h.p. the take-off is as exhilarating as it is short.  The wings, which are in fact a little less than ¾ scale (.63) initially suggests pretty high approach and landing speeds.  Some redesign of the leading edge and point of maximum camber have improved the stalling characteristics and made the approach and landing very comfortable.

The Civil Aviation Authority approved me as test pilot for the 40 hour test schedule during which we were blessed with near perfect weather.  Warren Denholm and his team at Avspecs did an incredible job of reassembling and preparing the aircraft for its first flight and during this time I was able to obtain an in depth insight into the systems.  Pilot’s Notes in the true sense were not available, so much of the first flight preparation was based on information gathered from all that we could find written and a video produced by the original designer Dan Denny.  Trevor Bland of NZ Warbirds loaned me his original copy of the P51 Pilot Notes and with this preparation we wrote our own manual and secretly planned our first flight.  Secret that is until I pressed the start button, the sound signature of the engine is unmistakable and our intention of flying unobserved was a complete nonsense.

The first flight was not without its minor drama, the tail rose almost instantly and the kick in the back was made all the more impressive when I discovered at about 200 feet I hadn’t managed much more than about half power.  The lightness of both elevator and aileron initially take one by surprise making for some interesting short term manoeuvres whilst the gear lever is moved to up.  The lever movement is rather stiff and even more so on extension which is associated with cable actuation of the undercarriage door release.  Lift off from the runway is at 90kts and requires a positive movement to prevent the wheels skipping,  clear of the ground the acceleration to 120kts is almost instantaneous and care needs to be taken not to allow the acceleration to continue above 150kts which is the limiting speed for the gear doors.  On this first flight, this became an issue in that a gear door light remained illuminated and a fly over revealed that the gear had retracted on top of the door.  We subsequently discovered from a photograph of the take-off that the door had not opened to receive the retracting leg.  Reuniting the aircraft with the ground became a very appealing option about this time so with a total flight time of 10 minutes I set up for the first landing.  Three greens were a reassuring indication when the gear was extended downwind and the landing was achieved without causing the assembled observers to fall about laughing.

Back on the jacks and many more retraction tests resulted in Avspecs achieving clean and consistent gear and door operation and we were able to move on with the test programme.

Some memories of the original mustang are of extremely heavy control forces at high speed.  This is not so in the Thunder Mustang, the controls are light and nicely harmonized throughout the speed range.    Maximum manoeuvre speed and turbulent air speed is 222 kts which corresponds to the original within just a few knots.  At this speed all the rolling aerobatic manoeuvres are possible with adequate speed margin and the ability to use full aileron.

Centre of gravity movement is permitted from 15-25% of the Mean Aerodynamic Chord (MAC) and can be very easily exceeded with two people, particularly if the rear passenger is of generous proportions.  Empty, the CG is forward of the forward limit and every addition of weight moves the CG aft,  additionally when the gear is raised the CG moves a little further aft.  With CG positions near the aft limit, the aircraft is predictably less stable and this is particularly noticeable in pitch.  In these more aft CG situations, very light hands are needed in looping manoeuvres so as not to high speed stall the aircraft or overstress the airframe.  There is no aircraft that can’t be overstressed but with the Thunder Mustang with a design load factor of positive 8.4 g and negative 5.6 g it would need to be gross mishandling or sheer stupidity that would exceed or even approach these limits.

The Thunder Mustang has electric trim for all three axes and is beautifully light and stable from the trimmed attitude.  Because of the significant speed and power range it is an aircraft that does require constant attention to trim but pilots will quickly settle into the routine of correcting trim as power and speed vary.  At an economical cruise speed of 230kts indicated and a consumption of 95 lts/hour, in still air one is covering 100 nautical miles consuming only 41 lts. 

High speed handling is as already described, crisp and light and with a Vne of 437kts; this is a bird with attitude and an engine note guaranteed to produce “goose bumps” the size of camel humps.  Take off to 10,000 feet can be achieved in just over two minutes and that represents around 45kts vertically. 

Around the circuit and in the traffic area we come back to pussy cat mode and have adopted the policy of extending some flap (electrically driven) so as to have a more compatible speed with other traffic.  This technique allows us to fly down wind and base in the 120 – 110 kt speed bracket reducing to 90 kts plus any wind and gust additives over the fence.  The flare is progressive to a short float and a positive cessation of flying to touch down on three points.  The wide undercarriage track makes for very stable ground handling and the tail wheel remains locked and steerable until the control column is pushed full forward when the tail wheel is released to castor.  The recommended cross wind limit from the USA is 12kts but the aircraft is capable of handling way more than that.