The First Flight of Spitfire I P9374
Looking through my logbook reminded me that I have test flown quite a few Spitfires. The types vary and include both Rolls Royce Merlin and Griffon engine examples. Some were “clipped wing” models and two were T-9 2 seaters.
In all cases, the various Spitfire Marks had similarities. They all had the engine driven hydraulic system to retract and lower the undercarriage. All were fitted with constant speed units to control the propeller RPM and all had the later metal covered ailerons.
P9374 has been restored to exacting standards and is a true Spitfire I. For me as the test pilot, this gave a few areas of discovery over the “standard” Spitfire air test. A Spitfire I fitted with all the early systems, engine and propeller has not flown since the end of 1940, as any aircraft flying after this time was “field modified” to enhance its modification state.
The aircraft is powered by a Rolls Royce Merlin 3 and a 2 pitch de Havilland propeller. The early engines were not the “power horses” of the later marks, this example giving 940 horsepower at +6 ¼ pounds of boost. They are also delicate engines to handle, the early one piece heads and banks being particularly prone to cracking and loosing coolant.
Having a two pitch propeller gives its own problems. There is no constant speed unit to govern the engine RPM and therefore the pilot becomes the governor, constantly monitoring RPM against boost or throttle settings. Thus, the pilot is responsible for any speed change in addition to giving an RPM change.
The airframe is simply early Spitfire design. I expected the controls to be quite light and responsive, thinking that a comparatively light aircraft and early design would probably reflect Mitchell’s intent closer than the later types.
Undercarriage retraction is a manual, hand pumped affair. Testing in the hangar showed this to be a very simple and easy operation. Whether this would change with the aircraft airborne and having air loads applied I did not know.
The ailerons are fabric covered rather than the later metal covered assemblies. This in itself I did not expect to give problems but I had asked Alex Henshaw about them just in case. He simply asked how fast I would intend flying! “Anything up to 400 MPH is fine John, over that they get a bit heavy “.
Reading the quite sparse Spitfire I pilots’ notes did not show any areas of additional concern and so I prepared for the first flight with a balance of excitement and trepidation.
Walking up to P9374 really impresses on you the fact that she is a Spitfire I. The straight legs of the undercarriage, balloon tyres and “baby” engine/propeller combination highlights of the many wartime pictures I had seen of Spitfire Is on the grass at Duxford.
With full fuel, myself and parachute, the aircraft weighed 5991 lbs and the centre of gravity position giving 6.6 inches aft of datum. Compared to the Spitfire I all up weight of 6200 lbs, she was not too far from wartime operational weight.
Strapping in was carried out easily and it was not long before I was at last on my own in the “office.” Taking a few minutes to settle down, I carried out my normal left to right check of everything.
Cockpit side door closed and locked Rudder trim tab at neutral Elevator trim tab, 1 division nose up Propeller pitch control at coarse Throttle, full and free and closed Mixture control – auto rich Throttle friction adjusted Electrical power switch – on Undercarriage indicator light switch – on Magnetos – off starter magneto – on Radiator door – open Flap control – up and air pressure – checked Flight instruments – checked Engine instruments – checked Fuel selector - on Undercarriage selector at “down” position Seat height – adjusted Headset lead – connected Canopy – free to slide and open Flight controls – full and free Brakes – on and checked – air pressure – check
With that done I was ready for engine start. The engine had been run earlier and so was still quite warm. If it had been cold, a good five loaded primes of fuel would be required. However, when hot or warm much less priming fuel is needed. I therefore gave three pumps of the primer and then screwed it back in the closed position. Opening the throttle ½ inch, I checked brakes on and with the stick hard back called “clear to start!”
With the propeller turning through its third blade the engine surged into life with a cloud of oil smoke and exhaust. What a lovely smell! Somehow you never get tired of starting a Merlin engine.
The oil pressure was instantly checked and was sitting happily at 60 psi. Selecting the propeller from coarse to fine position saw the oil pressure drop slightly and then return to normal. The engine was now running very smoothly and all the engine instruments were showing normal readings.
Due to the engine already being warm, I was conscious that I did not have a lot of time before take-off. The coolant temperature would rise quite quickly and so - with that in mind - I wove away the chocks, released the brakes and started the taxi out to the runway.
Directional control was good and only small amounts of brake were necessary to weave from side to side on the way to the runway. Coolant temperatures were rising toward 95 °C, so there was not too much time left!
Stopping near the end of the runway, I quickly went through the pre-take off checks
Trims – set Throttle friction – set Propeller – fine pitch Magnetos – On starter magneto – off Flaps – up Radiator door – open Fuel – on Pressure 2 ½ psi Instruments – set and checked Controls – Full & free Harness – tight Canopy – open and latched
I left the engine run up until last, as that would warm up the coolant even more. So with the stick fully back, I throttled up to 1800 RPM and checked the two position propeller and then the magnetos. All was fine and so I throttled back to idle at 550 RPM and confirmed we were ready to go. Coolant was now 110 °C!
Lining up on the grass I gradually pushed the throttle forward and the aircraft started to accelerate nicely. The first impressions were very important at this stage, and I started to feel the controls come “alive” and concentrated on whether they feel normal. Any large out of trim tendencies were better identified there on the ground rather than in the air!
The aircraft accelerated quickly and a quick glance showed + 5 lbs of boost and 2600 RPM. I left the throttle there and following a few bumps of Duxfords grass we were airborne!
I had briefed the engineers that I would not retract the undercarriage until I was happy with the engine and initial trim of the flying controls and so climbing steadily on the downwind leg I throttled back to + 2 lbs boost and selected “coarse” pitch on the propeller. It was like changing gear in a car from 1st to 4th! The RPM dropped from 2700 to 2050 RPM, very smoothly and the aircraft now wanted to accelerate beyond the undercarriage speed of 160 MPH.
The ailerons were not in trim and so I was holding a 2 – 3 lb roll left tendency. However, I felt this was acceptable for the time being and so selected undercarriage up and started to pump the handle. There was no increase in the loads over that experienced in the hangar, and so in good order the undercarriage retracted and the 2 up” lights showed red in the indicator.
Closing the hood, I now scanned the instruments for any signs of a problem, all was well and so I climbed the aircraft up to 3000 ft to carry out a stall check. In the climb I started to “feel” the controls some more and realised that this aircraft felt really nice. It was well balanced and apart from the out of trim aileron the controls were nice. Other things started to register as “different” from the other Spitfires. The canopy is the original flat sided version and so I was aware of a limitation in my head movement. Basically I kept banging my head on the canopy sides! Also the aircraft is relatively quiet in comparison to some of the later Marks. The coarse pitch propeller and Siamese exhaust stacks obviously keeping the noise levels lower.
3000 ft reached, it was time to slow down for the stalls. The first was a “clean” stall with undercarriage retracted and flaps up. I first trimmed the aircraft to fly at 105 mph and put the propeller back in to “fine” pitch. I did that because, if I needed the engine to recover from the stall, I would need the instant acceleration that fine pitch would give me.
Slowing through 75 mph the elevators gave a slight buffet and the nose and left wing dropped at 70 mph. Very nice! The book figure is 73 mph, so that was a perfect result. Accelerating away from that, I selected undercarriage down and started pumping. It took more pumps to get the undercarriage down than it did up but still it is a painless exercise and I have not yet lost the skin off my knuckles, which was an apparent injury for many early Spitfire pilots!
Slowing below 140 mph I selected flaps down. Wow! They went down very quickly and the aircraft instantly had a nose down pitch. Trimming back from that I noted the flap extension time as 1 – 1 ½ seconds.
The stall was again very benign and is a little under 60 mph. The book figure is 64 so again this was a good result.
I had been airborne now for about 20 minutes, and it was time to return for the first landing. We could then check for leaks that may have shown up and adjust the aileron trim before testing the aircraft further.
Flying through the airfield overhead at 500 feet, I slowed down to below 160 mph and lowered the undercarriage. I put the propeller into fine pitch, opened the radiator door, checked for green down lights on the undercarriage and slowed to below 140 mph for flaps. I was ready for their rapid deployment this time and trimmed the aircraft to 90 mph. Opening the hood caused a windy buffet through the cockpit, but what a feeling. I am flying a Spitfire I on finals to Duxford, the first airfield that the Spitfire became operational in 1939, a lovely sunny evening and an aircraft which was flying beautifully. I pinched myself and got on with the landing!
She flared at 75 mph and settled onto the grass – fantastic – no problems keeping her straight and she slowed to a walking pace for the taxi back. Puffs of oil smoke coughed from the exhaust stacks as I taxi in. The warmth and smell from the engine furthering my imagination of what it must have felt like as a 20 year-old Royal Air Force pilot let loose in a Spitfire I before the Battle of Britain. It must have been unbelievable, frightening and exhilarating all at the same time. With no slow running cut out on a Mark I, its Magnetos turned “off” and the engine slowed and stopped, I gave it a momentary “kick” just to burn of the last bit of fuel.
Everyone was ecstatic, as they should have been. This is a fantastic restoration that everyone should be very proud of, a lovely aircraft that flies beautifully.