WHO SAYS SIZE DOES NOT MATTER?
THE GRUMMAN AVENGER
When you think of a classic warbird you may be forgiven for considering only the smaller fighters, the Spitfire, Hurricane, Mustang and so on, but if you want a show stopper with Attitude look no further than the Grumman Avenger. A beast that flies with a 54 ft 2 in (16.51 m) wingspan and a towering height of 16 ft 6 in (5.03 m). When raised it bellows smoke and roars into action. The thundering sound of the Wright Cyclone C-14BB (R-2600-20) is a pure delight. There are presently only two examples of the type in Europe. One is owned by Tony Haig-Thomas and is based at North Weald in Essex and the other is based in France. My involvement started some four years ago when Tony took me under his wing and gave me my first start in the difficult to enter world of warbird display flying.
A WARTIME MOUNT FIT FOR A PRESIDENT (back to top)
The TBM-3 'Avenger' is a single engine, midwing all metal aircraft. It was designed as a torpedo bomber for carrier or land based operation. The Avenger was made famous by George Bush when the World discovered that he had flown the type during WWII - or did the aircraft make George Bush famous, eventually leading to him becoming President of the United States of America! The wing is of full cantilevered construction, with an outer panel folding arrangement of the 'stand-on-edge' and 'fold-straight-back' type. The Wright Cyclone, 14 cylinder radial, double row, air cooled engine drives a three-blade (13 ft 1 in (3.99 m) diameter) Hamilton Standard Hydromatic propeller. The engine is equipped with a single stage, gear driven, two-speed supercharger, and a Stromberg Injection Carburettor.
The aircraft was built to survive: armour is provided to prevent enemy gunfire reaching the pilot and the turret gunner. The hydraulic system operates in several different circuits, each of which is supplied hydraulic pressure from a central distribution unit. A separate control is provided for each circuit. During the aircraft's wartime role the crew consisted of a Bombardier, who was also the radar operator, that sat behind the pilot, and a Turret Gunner, who was also the radio operator, housed in the rear turret (not fitted on Tony's aircraft).
THE BRITISH AVENGER (back to top)
The Haig-Thomas Avenger, civil registration G-BTDP, is the biggest single-engine aircraft in this country. It was built as a TBM-3E torpedo bomber bearing the US Navy Serial Number 53319 and entered Service on 16 May 1945. On 17 May it was delivered to San Diego Naval Air Station and thence to Pearl Harbour where it stayed until April 1946. Later it was converted into a TBM-3R transport aircraft for the carrier on-board delivery role. In 1953 the Avenger operated from the decks of the USS Bennington and Valley Forge, returning eventually to Norfolk NAS where it continued to serve with VR-22, being used for shore-based operations to the fleet until placed into storage on 24 September 1954. Sadly, on 12 June 1956, she was retired from the US Navy after nine years with a total flying time of 1108 hours. August 1956 saw the aircraft being struck off charge and two years later, on 27 June 1958, it was registered as N3966A.
Some 20 years later, in May 1987, the aircraft was bought by Anthony Haig-Thomas. It was ferried, wheels down, to Grass Valley at the Nevada County Airpark for engineering work, returning to Chico in October 1988. Here it was flown for ten hours, as a proving exercise, before being ferried to Long Beach to be shipped to Britain, arriving at Felixstowe in February 1989. Once there the large size of the Avenger made conventional forms of transport almost impossible; it was decided that the simplest way to move the aircraft to Ipswich was by towing it on its own wheels for approximately 10 miles (16 km) along the A12 trunk road! It was flown from Ipswich during the summer of 1989 before moving to North Weald, its present home.
BEING BIG DOES HAVE ADVANTAGES (back to top)
My first thought as I walked out to the Avenger was its enormous size, everything about the aircraft is big, the propeller is massive, the wingspan enormous, the bomb bay huge and the undercarriage is most definitely built to cushion the aircraft's tremendous weight (18 100 lb (8210 kg) maximum wartime take-off weight) during the carrier operations for which it was designed. Once over the frightening size you are then faced with the problem of how do you get in - not easy unless your name is Chris Bonnington as it involves scaling the wing and climbing into the cockpit. Once in you feel that you are sitting on top of the Monster. It is a long way down and there is a mass of metal all around you.
The cockpit is spacious and typical of the wartime American aircraft. In keeping with the aircraft's size the seat is like an armchair in the middle of a large room, with the controls at arms length, although well organized. There is a lockable tailwheel (a god-send preventing the dreaded ground-loop), a throttle and mixture quadrant with large chunky levers and an rpm control of the 'vernier' type which sticks out of the left-hand side of the instrument panel. Its basic operation involves pulling the control out to the approximate rpm required and then fine tuning by rotating the control. This action moves the lever in or out on a 'tongue-and-groove' system giving precise control. The instrument panel is conventional with large instruments that are easy to read; on the far right of the panel are the engine and fuel instruments. A GPS has been sympathetically installed and looks like any other 'round dial' in the cockpit. Underneath the instrument panel are the cowl flap and air cooler controls as well as the wing-fold mechanism. The fuel-capacity is another 'large' feature of the aircraft: a total of 271 Imp gallons (1230 lt) can be carried in three tanks which is enough for about five hours' of flying. On the right of the cockpit are the circuit breakers, starting controls and other associated electrical items.
There is a side door on the right of the aircraft just by the tailwheel which gives access to the crew stations. Once the door is open the real advantage of the aircraft stares you in the face: lots of space. There is plenty of room to take an overnight bag (even if you are taking your wife or girlfriend with you!) and a drum of oil or two to feed the engine which has a real thirst for the stuff. Indeed, the engine uses about 2.5 gallons (11.4 lt) of oil an hour but the engine manuals say that there is no need to worry until a massive eight gallons (36 lt) an hour are consumed! Reassuringly the oil tank holds 32 gallons (145 lt). The fuel consumption is not on such a grand scale and is not much more than that of the Harvard (35 gallons (159 lt) per hour when cruising); however, the cruise speed of 140-150 kt (260-280 kph)is slightly higher than the Harvard's 120 kt (223 kph). The aircraft can cruise at 180-200 kt (335-370 kph) if required and has a maximum speed of 240 kt (445 kph). The operational maximum speed was 315 kt (584 kph).
IT MAY BE BIG BUT WHAT FUN (back to top)
Once you have mounted the Beast and strapped in, engine starting is relatively easy. First, if the aircraft has not flown in the past 24 hours, the pre-oiler is switched on for two minutes to pump an oil 'film' around the engine to reduce the engine wear during the first few moments of the starting sequence when the metal could be dry of oil due to drainage; then, to further protect the engine by checking for any hydraulic locks in the pistons, an intriguing starting ritual is completed. First, the propeller is turned through nine blades using the electric starter, if clear, its spun through a further six blades. The throttle is then set to 0.5" open, the booster pump selected 'On' and the electric starter switch held to 'Start' with the thumb; at the same time first finger is used to 'tickle' the electric primer switch for 1 second bursts. After the propeller has turned through 'three blades' the mags are flicked to 'On' and as the engine fires the mixture is moved slowly to auto-lean, at the same time releasing the starter; the primer is still 'tickled' until the engine is running smoothly. While all of this is happening the aircraft is engulfed in blue smoke as the residual oil in the engine is burned off - an incredible sight.
When taxiing the view is excellent except immediately below the nose, so a gentle weave is still required. The tailwheel at this stage is in the 'unlocked' position giving the aircraft a very tight turning capability.
Engine checks are conventional with the mags being tested and the CSU being exercised; there is little tendency for the aircraft to 'nose-over' but very high power needs to be avoided. The take-off is very easy even with 2800 rpm and 49 inches of boost! At take-off power the propeller produces a tremendous vortex behind it which increases the flow over the big wing causing the aircraft to leap into the air before you have had time to gather your thoughts. Rotation happens at 75-80 kt (144 kph) with the aircraft accelerating rapidly to the climb speed of 140 kt (260 kph) (you have to be quick to get the gear up) when power is reduced to 2000 rpm and 30 inches. You now get a chance to sit back and take in the sheer size of the aircraft and the roar of the enormous engine. The wings look even larger now and you feel extremely safe in this 'Volvo' of the air.
The control forces are very heavy and trim needs to be used to keep them manageable. However, the aircraft's ability to fly well at 90 kt (167 kph) and also at 220 kt (408 kph) is very impressive. The large lifting force generated by the wing gives the aircraft a very tight radius of turn and although aerobatics are not permitted the aircraft is very manoeuvrable. Stalling is not such fun and definitely not for the faint hearted; in common with other American aircraft of the same vintage the landing configuration stall is very violent and will have you on your back in no time! But that is the only vice I have come across with the aircraft.
Back in the circuit the Avenger really comes into its own. There is no problem with losing speed on the 'break' as the undercarriage can be selected down at 200 kt (371 kph). Flaps are selected at 130 kt (241 kph) and Finals is flown at 110-100 kt (195 kph). Visibility is good throughout even as the speed is reduced to the threshold speed of 85 kt (158 kph). Cutting the power and gently flaring produces a touchdown at approximately 70-75 kt (135 kph). Unless flown regularly, it is quite difficult to produce a good three-pointer as the sheer height of the aircraft catches you out and there is a tendency to touch the main wheels about 5 ft (1.53 m) before you think you should! This does not cause any real problems but you need to be ready to 'chop' the power immediately, thereby, reducing the airflow from the propeller helping the aircraft to stay down. With the tail on the ground there is no problem stopping. When back on chocks the engine is run at 1200 rpm for a minute to scavenge the engine of any excess oil before selecting the mixture to cut-off. As the propeller slowly runs down (because of its large size) there is just enough time to consider the excitement that's just been had in this big but fun machine.
AN ELEGANT AND EXCITING DISPLAY (back to top)
Form an airshow perspective the Avenger has all the qualities needed from an aircraft: relatively unique this side of the Atlantic, its big and can not be ignored, there is plenty of space inside for creature comforts and it carries plenty of fuel. The latter point is of particular importance if you can pick up free fuel at an event!
The display itself can be every bit as exciting as the perceived more sprightly, smaller warbirds. Indeed, with the Avenger the display starts when the aircraft is parked on the line in front of the crowd; because of its enormous size everybody wants to take a look. Add to this the spectacle during the starting process, when the aircraft is engulfed in a cloud of blue smoke and the engine roar is deafening, and the airshow organizer is already getting value for money before the flying part of the display has started. Even when taxiing the aircraft draws the eye of the crowd - everyone will start waving and, because you sit so high, the crowd can easily see a returned wave; again, adding to the presence of the machine.
For the airborne part of the display I try to produce a flowing routine that shows off the aircraft's capabilities as well as trying to keep it as close to the 'paying customers' as possible, thereby, producing the maximum number of photographic opportunities as well as keeping the sound of the engine within hearing distance. I try to take-off before my allotted slot to give time to clear away from the crowd and climb to 2-3000 ft; this allows the routine to be opened with a maximum speed run at 100 feet (30.5 m) above the ground and along the display line demonstrating that the Avenger may be big but it has plenty of get up and go. It is also the first chance that the crowd gets to hear the awesome roar of the engine at 2000 RPM and 30 inches of boost. At the end of the pass there is plenty of energy to perform a '270' turn back towards display centre followed by a steep pull-up in front of the crowd. This is my favourite manoeuvre and gives the picture takers an unusual profile 'shoot' of such a big aircraft; its also a way to lose all the energy from the first pass and bring the aircraft low speed when the big wing really is in its element. From the top of the pull-up a wing-over is performed into a very tight descending '360' degree turn (at approximately 120 knots/222 kph) culminating in an accelerating dive back to 100 feet (30.5 m) for the next manoeuvre. The tightness of any manoeuvre is accentuated by the size of the Monster which makes it look closer than it really is. This means that you can afford to use less 'g' than you would need to use in one of the smaller fighter aircraft. I aim to use no more than 2.5-3g during the display which gives plenty of margin before the maximum of 4.6g and also adds in a buffer to correct any small judgement errors. In fact because the aircraft handles so well at low speed and has a lot of engine power the majority of the display is performed slow where only small values of 'g' can be 'pulled'; this demonstrates the aircraft's agility well and keeps the display very compact in front of the crowd - one of the Avenger's main benefits, almost no time is spent out of 'picture' range repositioning for the next pass.
After the first couple of manoeuvres I try to complete a wing-over to arrive behind the display axis at one end. This allows the next pass to be concave towards the crowd with 50-60 degrees of bank; again another very good photo opportunity. Depending on how much time is left a gear down pass adds to the display variation and unlike most aircraft the Avenger has such a high gear limit speed (200 kt (371 kph) to extend and 150 kt (278 kph) to retract) that you do not need to be slow, and thus poorly placed should the engine have a problem. A good end to the airborne part of the show is to run along the crowd waggling the wings to say goodbye before 'breaking' to land. During the taxi back there is a final chance to wave at the children who are frantically waving at the spectacular Monster that has just been darkening the sky in front of them.
One of the best things about displaying the Avenger is that there is no need to display 'on the limits'; the aircraft is so big and handles so well it appears 'spirited' and 'close' - the crowd are not used to such a big aircraft being so manoeuvrable. However, it needs to be said there is a price to pay for this manoeuvrability - LARGE STICK FORCES. It was after all designed as a Torpedo Bomber which required high stability to be a good weapons platform; the consequence of such stability is very high stick forces when the aircraft is moved from its trimmed position. During airshow manoeuvring where the aircraft's speed and flight path are changing rapidly the problem is made worse and lots and lots of trim is required. It is the only aircraft that I have displayed where you almost have to use 'pre-emptive' trim by taking large handfuls whenever they can be snatched - there is no finesse just a desire to relieve as much stick force as possible as quick as possible. Even with this technique an eight minute display is better for your fitness programme than any workout in the gym! (and a lot more fun.)
The aircraft will be back on the display circuit next year. For further details about booking the 'Beast' for your next airshow contact Tony Haig-Thomas on telephone UK 44 (0) 1255 674063.
BACK TO TOP