Flying the Chipmunk
By Capt RE Gillman
Senior Training Captain BEA Elizabethan Fleet
This article is taken from Over to you! the official newsletter of the Airways Aero Club. No 39 - February 1957.
On being invited to Croydon for the purpose of flying one of the Club's Chipmunks, I accepted with alacrity for two reasons. In the first place, I was very keen to try this aircrat which by reputation and appearance, promised a good afternoon's sport, and secondly, Croydon iteself has a certain sentimental attraction for me.
I always associate the familiar control building with the intimate atmosphere of pre war civil flying activites, when striking personalities were the rule rather than the exception and the "press-on" spirit born of enthusiasm was likely to prove highly infectious. My civil flying career began at Croydon, and walking on to the tarmac, I remembered with a shock at the passage of time, that it was over ten years ago that I had landed a DH.86 there for the last trip under the colours of the Railway Air Services. I felt pleased on reflecting that despite the many changes in other ways, the face of Croydon remains the same; a familiar and pleasant reminder of a fascinating period in civil aviation.
Mr. Burridge introduced me to the Chipmunk, and I was struck by its workmanlike appearance and excellent finish. The cockpit, for an aircraft its size, is not unduly cramped, and the layout of instruments and controls has a slightly military flavour, as if one woere looking at a junior fighter.
The mixture control and throttle on the left, are mounted on the left, are mounted a little too close to the fuselage for my liking, and with gloves on I found it difficult to get a good handful of throttle. However, it did not prove troublesome in flight, a finger and thumb being all that was necessary to gain accurate control of the engine.
The elevator trip down by the left hand is nicely positioned, and the brake lever can be reached with comfort even when fully off. On the cockpit floor is the fuel cock which copes with the supply for the two wing tanks, no changeover procedure being necessary, and beside this is the familiar P12 compass. On the starboard side one finds the flap lever, a large business like affair having three positions, and this is the selector for the four channel VHF. That seemed to be about all that one needed to know to start with. The harness was, I thought, a great improvement on the old Sutton Type, due to the ease with which it could be tightened and relaxed, and although the lower half was more of a lap strap than anything else, I found it kept me firmly in position during aerobatics.
The engine was turned over by hand for the preliminary sucking in and started with ease on the electric starter, and at a thousand r.p.m., it ticked over fairly smoothly.
For taxying, a couple of notches of hand brake were engaged, and it was found that movement of the rudder bar gave positive differential braking. This was needed, for although the cockpit cut-off angle is very low, the oblique view through the side-screen was somewhat distorted, particularly on the starboard side, and the unusually narrow perimeter track at Croydon, necessitated a constant swinging of the nose if one was to be happy about the way ahead.
At the take off point, a brief engine run was followed by the vital action check. Elevator trip 4 deg. nose down, throttle nut adjusted, mixture fully rich, carburettor air cold, fuel on and suffient for flight, (the two nine gallon tanks have their guages positioned on the wing roots) flaps up, gyros uncaged and hatches and harnesses secure.
During the take-off run, there was no appreciable swing, and at the full power speed of 2200 r.p.m. the 50 knot unstick speed was reached in about two hundred yards. Even with that amount of nose-down trim, the machine unstuck with the lightest of stick movements, and the nose had to be pulled up steeply to keep the speed down to the 70 knots recommended for climbing.
An unstable easterly airstream had brought in some smoke from the Estuary towns, so a course was set for the south eastern free lane, where the visibility looked somewhat better.
At the lower levels, the air was fairly turbulent, particularly over the North Downs, but the pitching stability of the machine was quite remarkable in something so small, and the positive elevator with its powerful trip support, made it possible to hold height accurately. Stability in the yawing plane was also good, but a certain amount of aileron work was need to counter the bumps. Fortunately, the ailerons are light and effective throughout their range, and the slightest of stick movements is all that is required to counter a wing drop. At 2,000 r.p.m., the aircraft purred away quite happily at an indicated 90 knots.
Once clear of the airways, we climbed in an area where the cloud was more broken, until at four thousand feet, in smooth air, we levelled off for some stalling.
I tried out some steep turns while "looking out below", and although quite a bit of rearward stick movement is required to keep the nose running round the horizon, 60 deg. of bank can be held quite comfortably in a rate 4 turn. Repeating this to the left, I found the nose dropping more markedly, and it was then that I noticed for the first time, that the initial figure on the CSI is 2,000 f.p.m. Unconsciously from the outset, I had assumed that this was the normal thousand mark, which only goes to show how one takes instruments for granted.
Straight and level once again, the power was pulled off and the nose held up by a long rearward movement of the stick, until at around 50 knots, a little pre-stall buffet was felt, and 5 knots later, the nose dropped sharply, and the left wing flicked over. This was checked with light application of rudder, and recovery made in the normal manner. Pulling down 30 deg. of flap, resulted in a strong nose-down couple which was easily trimmed out by the very powerful elevator trim, and this time, the stall occurred around 40 knots, again, smartly dropping the left wing.
The spinning exercise was somewhat unusal, and having been forewarned by this, I was rather curious to try it out. On intr5oducing the spin with full rudder at the stall in the normal manner, the aircraft begain to rotate fairly fast, but the speed increased although the stick was still held back, and at 100 knots, the whole manoeuvre was noisy and uncomfortable, but recovery was simple enough, though at rather high airspeed during the ensuing dive. Althought he aircraft turns at such a speed as to give an impression of autorotation, it can still be nothing more than a spiral dive. A full spin was achieved by applying opposite aileron, after the stick had een brought back centrally, thus stalling the inside wing completely on a subsequent occassion, and the resulting spin was fast clean, and a positive forward movement of the stick was required to regain control.
The next item was a loop, and the nose was pushed down with plenty of engine on initially. At 130 knots, a slow movement of the stick brought the aircraft round in a wide smooth loop, and although when at the top, a glance at the ASI showed it to be reading 40 knots, no marked tightening of the loop was necessary to keep one's bottom on the seat.
The slow roll was more like that produced in a modern fighter, for the crisp ailerons took it round at such a speed that at no time did the engine cut. At 120 knots, the nose was pulled about 20 deg. above the horizon and full aileron applied. The nose rotated smoothly around a fixed point for the first half of the manowuvre, and a limited amount of forward stick movement was needed to maintain level flight during the inverted stage. On the roll out, however, there is a distinct tendency for the nose to drop, and full top rudder has to be applied to negate this. Mr. Burridge assured me that three rolls could be complted from that starting speed without losing height, and I can well believe him.
The barrel roll in this machine, is extremely comfortable, the snappy ailerons and positive elevator giving excellent control throughout.
At this stage, I was becoming aware that thanks to the hospitality of Len Wenman, I had lunched not wisely, but too well. My stately airline stomach had taken serious offence at the treatment meted out to it, and the pork chops had made one circuit too manu. When "Budge" suggested returning to Croydon, the motion was carried without division.
Back in the circuit, the flap was lowered in two stages, and teh nose down moment trimmed out so that a power-off approach was made with no stick load at 70 knots. This was reduced to 65 over the hedge, and the low cut-off angle, and effective elevator made the flare-out easy to judge. There being rather more elevator than is actually needed, getting the tail down presents no difficulties, and during the landing roll there is no tendency to swing.
I think that the Chipmunk can be classed as "the poor man's Spitfire". It has all the qualities of a thoroughbred with none of the temperament, and if is rather expensive to hire, then for the real pleasure to be enjoyed, it is money well spent.
I would very much like to fly it again 'ere long, but I think it had better be before lunch next time.
Note from February 2009 - The club still maintains a de Havilland DHC1 Chipmunk among it's fleet, which can be hired out for trial flights from £120.
