Flying the Gladiator
Often described as one of the last great biplane fighters, the Gloster Gladiator is one of my favourite aircraft. To me it seems that this aircraft more than any other in the Collection spans the gap between the age of graceful 1930’s silver- winged biplanes and the purposeful war machines that followed. The airframe itself is a thing of beauty with those wonderful silver fabric covered wings and elliptical tailplane, but under this exterior there is punch in the form of an 870Hp Bristol Mercury radial engine along with 4 (inhibited) Browning machine guns. Much has been written about the history of this unique aircraft but this is what she is like to fly.
Ergonomics had not been invented when the Gladiator cockpit was designed and although the main instruments are arranged in the standard ‘T’ layout, the remainder are scattered in a rather haphazard array. The control column has a WW2 style spade grip housing a brake lever and buttons for radio and guns. The pilot seat is surrounded by exposed metal tubes, which provide mounting points for the various other control levers. The adjustable seat and rudder pedals make it easy to find a comfortable position and side panels on either side of the cockpit can be lowered on the ground to enable the pilot to lean out for a better view forwards whilst taxiing. The aircraft was one of the first to incorporate a glazed sliding hood although I always fly the aircraft with the hood locked in the open position. The pilot’s feet are supported below the rudder pedals on 2 metal trays and there is no cockpit floor. This means that anything that is dropped will disappear into the bowels of the aircraft and great care must be taken with pens and maps etc.
After some basic cockpit checks, including checking the operation of the hydraulic flaps (raised and lowered using a large hand pump lever next to the pilot’s left thigh) and priming the engine by pumping the Ki-Gass handpump, I am ready to start. With the brakes set, external power connected and chocks in position the 2 main magnetos are switched on along with the third starting magneto. The throttle is set only about 1/8” open and the Ki-Gass pump readied for another shot to help the engine should it fail to catch. The throttle should not be moved during engine start as the powerful carburettor accelerator pump could provide too much fuel and cause damage by fire or explosion. The electric starter turns over the big radial slowly and she catches quickly and roars into life. My eyes scan the oil pressure gauge to ensure that all is well whilst I adjust the RPM to about 600 for warm up. A reasonable oil pressure of about 65 psi must be quickly obtained as in a big radial such as this the oil provides vital cooling to the engine’s big end. At this stage the Ki-Gass pump is firmly screwed shut, the starting magneto switched off and the fuel selector switched to main tanks (the gravity tank is used for start as it provides an additional head of fuel pressure). Ground power is disconnected and the gauges checked for stable oil pressure and sufficient oil temperature before engine run up. This is achieved in about 4 minutes and I normally taxi forward and point the aircraft into wind for the engine run up at this stage. This avoids too much prop wash over any spectators close to the public enclosure fence. The engine is supercharged and hence as the throttle is opened power is measured in psi on the boost gauge. The engine is currently cleared to 4.5 boost for up to 5 minutes per flight although in practise little more than 1 psi is required for takeoff and display. For engine run up 0 boost is selected and the corresponding RPM of about 2000 confirmed. Each magneto is tested in turn and after a confirmation of engine tick over I am ready to go.
The aircraft is easy to taxi and the air pressure for the pneumatic brakes is continually recharged from an engine driven pump. This is in contrast to the Hind, which has a ground rechargeable pneumatic supply bottle that must be used sparingly. As with many aircraft from this era all the way up to the Hunter, differential braking is used in the Gladiator to aid steering by pushing forward on the required rudder pedal whilst squeezing the bicycle type brake lever on the control column. As mentioned, the lowered sidepanels aid forward visibility although the aircraft must still be weaved from side to side to check for obstacles. Whilst taxiing, I select the air intake shutter (or carburettor heat as it is known these days) to ‘Hot’ with a knob adjacent to the throttle. This is important as the Mercury engine is very prone to carburettor icing, a phenomenon that can still occur on a hot summers day due to the temperature drop as the air pressure is reduced in the carburettor venturi tube. In fact carburettor heat may be used throughout the flight except during takeoff or landing. The problem is exacerbated, as there is no carburettor temperature gauge, unlike in the similarly engined Lysander where the carb-heat gauge is a most valuable and frequently scanned instrument.
Having completed a few simple checks, we are now lined up for takeoff. I open the throttle slowly and the big radial begins to rumble as the aircraft slowly starts to accelerate. The view directly forward is non existent at this stage although it is important that I keep straight as engine torque is large compared to the low rudder effectiveness at low speed. I therefore continually glance at the side of the runway (the only bit that is in view) and correct any small swing with a dab of brake. I also start the takeoff run with the stick hard back to keep weight on the tailwheel and keep her running straight. As speed gathers I ease the stick forward and push the throttle further forward, checking for 1psi boost on the gauge. However, I take great care not to look inside for too long lest an unwanted swing develop. As speed increases the coarse pitch propeller becomes more aerodynamically efficient and we begin to accelerate more rapidly. The rudder is now effective and I ease the stick further forward to raise the tail. I now have a decent view ahead for the first time and at about 60 knots the Gladiator lifts off. I now reselect the intake air to hot, select the main fuel tank and have a close look at the engine instruments.
Safely airborne, I take time to enjoy the wonderful sensation of flying such a classic aircraft. It is a beautiful summer’s day, the silver wings are gleaming and the wind blasts around the cockpit to the muffled roar of the engine. This is how flying was surely meant to be! The Gladiator is a real pilot’s aircraft. She is manoeuvrable, with fairly light, well-harmonised controls. These days, maximum speed is limited to a little over 200 knots but during a display I will fly with the boost set between 0 and 1 giving speeds of around 130 – 160 knots. Aerobatics in the form of loops and rolls are permitted using entry speeds of about 160 knots. However, great care must be taken not to slam the throttle open as this will cause the powerful carburettor accelerator pump to flood the engine and cause a possible stoppage. Furthermore, the carburettor is intolerant to anything less than about 0.5g. For this reason we limit the entry height of aerobatic manoeuvres to 1000 feet above the ground and do not demonstrate them during every display.
For landing, the air intake control is set to (or confirmed at) Hot, the gravity fuel tank is selected and I recheck the fuel pressure and engine oil temperature and pressure. Brakes are confirmed off and speed is reduced to below 78 knots to lower the flaps. These are first selected down with a small lever on the left side of the cockpit but will not travel until the large hand pump lever is operated. It takes about 5 strokes of the pump to lower the flaps. The flaps provide a large amount of drag and a reasonably large trim change. I adjust power to maintain about 65kt on finals with a reasonable rate of descent. The hedge is crossed at 55 knots and the aircraft eased into the 3-point attitude for landing. Forward vision is now again poor and it is critical not to let any swing develop. This is because the aircraft’s centre of gravity is a long way behind a fairly narrow track undercarriage. Hence any swing could rapidly get out of hand as rudder control power reduces due to the decreasing airspeed and the blanking effect on the rudder of the bulky fuselage in the tail down attitude. The secret is a good 3-point landing followed by moving the stick hard back to get some weight on the tailwheel. I then go into ‘high gain’ on the rudders to keep the aircraft perfectly straight as she slows. Not really that difficult but this is not an aircraft in which to relax during the landing roll!
So that is the Gladiator. A beautiful, rare and historic aircraft with a unique place in aviation history at the changing point between 2 great eras of development. For a pilot she is an absolute delight to fly and she is one of my favourites in the Collection. What is the worst aspect of flying the Gladiator? Getting out!