Big Build: Pitts Model 12

Part Two of build­ing, test-fly­ing and dis­play­ing the 400hp Pitts Model 12

Pilot - - CONTENTS - Words: Peter Borchert Pho­tos: Keith Wil­son

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.

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.

Test fly­ing

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.

Dis­play Fly­ing

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

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