Big Build: Pitts Model 12
Part Two of building, test-flying and displaying the 400hp Pitts Model 12
Part 2: time to test-fly and display the 400hp Pitts
It was in the fourth year of the build of my Pitts Model 12 project when I began to plan the move of the completed fuselage and wings to Old Sarum Airfield. Once I had carried out engine runs outside my workshop at home, I was ready to do so. It was an important step when the wings and fuselage would come together to form a complete aircraft for the first time. When everything was put together, my LAA inspector Rob Millinship would do a final inspection, weigh the aircraft and check the centre of gravity. Then the paperwork could be submitted for a Permit to Test. I had long thought about flying the maiden flight myself. It was part of the package of dreams I had when I imagined building an aeroplane. Rob encouraged me and I applied to the LAA. An informal interview with Chief Engineer Francis Donaldson was followed by form filling and references−to check that I was suitably qualified. By this point my flying included several hundred hours on Pitts Specials and also a few
hundred in aircraft with the Vedeneyev engine, but I still wasn’t sure I would be accepted. Several months passed before I received a very welcome letter confirming that I could pilot the first flight and test programme. It was summer 2017 and airshow season; I’d kept my solo aerobatic displays current, displaying one of the Yakovlevs team’s Yak-50s. I had what would begin to seem like two unrealistic ambitions: to complete the test flying in time to attend the LAA Rally, and then to do my first display in the Model 12 at the Shuttleworth Old Warden end of season airshow. Both were in early September. I have had some experience of test flying. When the Yakovlevs display team take their aircraft to China and India each year, the aeroplanes are broken down to wings and fuselage and shipped out in containers. Reassembled, they display at a number of events and are then once again dismantled for the return journey. I have test flown the reassembled Yak-50s as part of the process of getting them cleared to display back in the UK. This routine test flying has its challenges but taking an aircraft on its very first flight is something else altogether. I have to admit I was a little bit terrified! Irrational, really. Test flying does have a higher risk than normal flying but−just like each flight we make−it is a very rational process of assessment and containing the risks. While I was waiting for the permit I had two generous offers that were to help me prepare for the first flight. First, I got to fly an hour of circuits and aeros at Cranfield on Will Wright’s American-built Pitts 12 – at that time the only one flying in the UK. Secondly, Mark O’leary (a Pitts 12 builder) loaned me his newly acquired Pitts S-1. I flew his 200hp Pitts every day for a week until I was happily back into the groove of Pitts flying. This all helped me enormously to face my apprehension. I was content that I was now current in the skills I needed for my first flight.
When the Permit to Test arrived I checked the aircraft and checked it again. When it seemed like there were no more excuses not to fly it, I began to consider the weather and set a day. It was important to me that I didn’t have any distractions and my plan was to sneak in the first flight late one day when no one would be around.
On the day it was perfect summer weather, five knots down the runway and blue skies. There was, of course, much to consider. Rob had set out what I should achieve in the first flight. The aim, generally, is to carry out a simple flight. Take off and climb above the airfield, check the engine parameters, carry out a couple of stalls to check stall speed, and then land. Before the day I walked both the overshoot and undershoot and carefully planned for an engine failure. On the day I briefed the ground crew and the airfield fire truck was on standby. I called Boscombe Down, home of the Empire Test Pilot School, who could not have been more helpful. When I told them I was making the aircraft’s first test flight they offered to keep the airspace above Old Sarum clear of their traffic for my flight.
My plan was to sneak in the first flight late one day with no one around
Despite my plans to avoid any distractions, by the wonders of social media, word had got out and there was a small crowd waiting. I was thrilled by the interest and for a while, of course, distracted. Display pilots are used to this and the pressure from the gaze of spectators, but this was quite unlike any display flight. However, there comes a point when the canopy clicks shut and the outside world disappears and you get into the zone−just like any other flight.
I had already carried out a few hours of engine runs at the airfield. The subtleties of starting and taxying had become familiar and intuitive. Starting is complex:
it’s one of those aircraft where you must develop a system or you will run out of hands. You have to hold the stick back whilst applying foot brakes, press to start (and maintain pressed) whilst switching on the mags, and adjust the throttle if needed. When it all comes together and the engine is rumbling away− waiting for the oil temperature to rise−in the minutes that follow there’s time to contemplate the flight.
In a Lycoming-engined aircraft the propeller is right turning, when viewed from the cockpit. The Vedeneyev rotates to the left. The different direction of rotation has opposite prop wash effects on takeoff. In the Pitts 12 during the takeoff the propeller effect causes it to yaw to the right. Often referred to as the ‘swing’, it must be countered with left rudder. The amount of yaw is proportional to the amount of power but also the rate at which it is applied. Gentle and smooth application of power will keep the yaw controllable with the correct rudder input. So now, on this first flight, as I line up I pause for just a moment and in my mind I rehearse which rudder input. In an aircraft that weighs 705kg and has 400hp everything happens very, very quickly. With only half-throttle, and from the three-point attitude, lift-off occurs in approximately four seconds. Once airborne full power can safely be applied.
For the first takeoff all went well and, as expected, it leaped into the air−and I tried to keep up.
As I was climbing away there was a problem. With the propeller pitch set to fully fine and with full throttle I checked the engine instruments. At the best rate of climb speed I was climbing steeply and all seemed well but, oh dear, the rpm showed the propeller (and engine) was over-speeding. Maximum rpm should be 2,900; it was showing 3,200. It wasn’t a terminal problem but of course it did occupy my thoughts as I climbed above the airfield. What had gone wrong? Was it the propeller... the governor? Max climb rate is around 3,000fpm and even in a normal takeoff there is little need for max climb, so I brought the propeller speed down for a leisurely 2,000fpm climb and parked the problem in my mind to deal with later.
My planned height of 2,000ft for a wide orbit of the airfield arrived quickly and I settled down in level flight. And then−a bit like on that first solo when you look across to the empty seat−i had a flash of consciousness that here I was flying the aeroplane I’d built.
But it was too early to relax. I had to carry out a couple of stalls to establish stall speed, calculate my approach speed and then land. I’d done the maths on the ground and, after a couple of stalls, I was relieved that the stall speed of 65mph (57kt) was ‘as design’ and the approach would be as expected at 86mph (75kt).
There was always going to be some angst about the first landing. Landing any Pitts Special requires skill and focus.
Even after years of Pitts flying it will make you look like a beginner if you are not paying attention. But having flown Will Wright’s aircraft I’d found landing the Model 12 rather easier than a Pitts S1. Not without its challenges but it is rather flattering to land. All the same I was relieved when, for this important first landing, I greased my touchdown, rolled to a stop and taxied off the runway. It was an extraordinary instant when I felt elated with more than just happiness. After I had taxied, shut down and completed my checks I just sat still inside the aircraft thinking about the flight before I opened the canopy to let in the outside world – the small excited crowd and their cameras, and an overspeeding propeller to sort out.
The propeller was a simple fix. A replacement governor arrived and was fitted within a week, and after some engine runs and calibration of the new governor I was ready to start the test schedule.
The LAA had sent me a test programme for aerobatic aircraft. Generally this included a check of the usual flight test parameters of non-aerobatic aircraft such as stall speeds and measured climb at different all up weights, Vne dive etc, plus a set of tests for aerobatic types. These included spinning−erect and inverted at different all up weights−and a list of aerobatic manoeuvres.
Before I got started it was important that I did some studying to prepare for the rigours of the test flying. Firstly it was going to be necessary to revisit some aerobatic theory, particularly for the erect and inverted spinning−just in case things didn’t go as they should. My reference here was Alan Cassidy’s book Better Aerobatics. I also got a copy of the test report on the only Model 12 registered in the UK – Will Wright’s aircraft. The test flying had been carried out by Shuttleworth Collection Chief Pilot Dodge Bailey. His written assessment of that aircraft was meticulous (of course) and was a great help to me.
I commenced the spinning trails with some caution−and a parachute. Once I got started− and after repetition, at different all up weights and centre of gravity positions−i became more and more confident in the aircraft. In fact it flew just like a Pitts! All went well, flight time started to build and I began to relax a little as I filled in more of the tables and forms with the test results.
With the test programme complete, I submitted the data to LAA Engineering for them to scrutinise and I waited for the full Permit to Fly. For the initial issue of this permit−the equivalent of a Certificate of Airworthiness for a certified aircraft−the LAA must refer to the CAA. I was warned to expect a delay and also that, now the test flying was complete, flying in the aircraft had to cease until the full permit was issued.
My plan was to attend the LAA rally and make my first display at Old Warden’s end of season airshow in September−both events on the same weekend−but the permit only arrived on the Wednesday before. Too late for me to be airshow ready but I did make it to the LAA rally and I am so glad that I did. When the LAA judges looked at my aircraft they gave it their highest concours d’élégance award−the Prince Michael of Kent Trophy. It was a great end to its first year of flight but its airshow debut would have to wait until the next season.
The winter brought a break in flying but, come spring 2018, I began to work up my display sequence.
As an airshow aircraft the Pitts 12 has a great presence that starts on the ground. Although mine has a front cockpit with dual controls, I fly it with a singleplace canopy that gives it a look of a 1930s racer, its biplane and radial engine combining to give it the character of a pre-war aircraft. With that engine−always something of a drama to start, putting out lots of smoke, and then of course the noise of a radial−you get the attention of an airshow crowd even before you get airborne. And its implausibly short takeoff run and steep climb make the Model 12 a great airshow aircraft. Relative to every
The Pitts 12 has a great presence that starts on the ground
Pitts before it is big and it is noisy.
The Model 12 will fly unlimited level aeros. Sadly, a number of Model 12 airshow pilots have been killed in America, having been too ambitious. A common error has been underestimating the height needed to recover from a baulked gyroscopic figure. My solo aerobatic Display Authorisation is to advanced level, but as the years go by the probability of Old Man Death reaching out a beckoning hand becomes more likely. I decided to keep the display sequence simple. A useful asset of a powerful aircraft is vertical penetration− the height gain−from the base height of a display. With the Model 12 this can be exploited, flying up into vertical figures from a base of only 200ft. Of course this means you can fly low and in front of the crowd.
My debut in the aircraft was in May at the Abingdon Airshow−a great event at a perfect venue.
It’s a beautiful sunny day. I am strapped in with the engine rumbling and ready to taxi out. My display slot is in three minutes and I am smack on schedule. I have my sequence card clipped up in front of me, the altimeter is set to the QFE, and I blip my smoke switch to check my smoke… nothing. I move to look behind me and try again… nothing! By now I get a call on the display frequency to taxi onto the runway to take off and display. Damn, I am going to have to display without smoke.
The flying went well but my smoke system had failed. It was a disappointment. Display smoke is an essential part of the spectacle and before my next show at Bicester Flywheel I found the cause of the problem (electrical). After some helpful advice from airshow pilot Rich Goodwin, I also decided to upgrade the smoke pump and increase pipe sizes to maximise the flow. The system now empties the six gallon tank in a five minute display−and the smoke trail is quite brilliant!
The summer went well including a flight in July−exactly a year to the day after its first flight−to Germany to meet Jochen Brune, a professor from Reutlingen University where they are building a Model 12. This was also the beginning of a new project to display at airshows in France and Germany.
In my dreaming about building this aeroplane, I would one day display it at Old Warden. I first displayed there in 1999 and have displayed each type I have flown ever since. I missed my chance in the Model 12’s first year of flying but in September, at the end of the 2018 season, I flew at the Shuttleworth Heritage Airshow, just like I imagined, under perfect blue skies.
The Model 12 is actually a two-seater, the ‘single-place’ canopy hinging open sideways to reveal the minimally-equipped front cockpit
ANTI-CLOCKWISE FROM TOP: Peter kitted out his Model 12 instrument panel in classic fashion for VFR operation; he grouped the electrics on the starbord side; with circuit breakers to the right of the seat; and put the magneto switches, throttle, propeller control and trim on the left
BELOW: seat and canopy are configured to accomodate parachute and flying helmet
First flight: Peter climbs away from Old Sarum
LEFT: with 400hp in an aircraft that weighs less than three-quarters of a ton, performance will not be lacking
ABOVE: a smoke system is fitted for display flying
BELOW: with so much power available, knife-edge flight is readily sustained
ABOVE: shot from ground level at Old Warden, these images give a vivid impression of Peter’s display sequence