13 August 2014

Flying the De Havilland Chipmunk

The De Havilland Chipmunk, or “Chippie” as most affectionately call it, is a 1950’s British trainer. With 1283 produced from 1947 to 1956, this aircraft gave many student pilots the opportunity to experience true freedom and spread their wings. This particular Chipmunk is one of the Canadian ones.

The Chippie, clad in her red-and-white fabric-covered fuselage and wings doesn’t look too imposing. But once standing next to it, you get a true sense of its size and realise it’s actually a fairly large aircraft. Equipped with an inverted inline Gipsy Major Mk8 engine, the propeller spinner sits around 1.7m off the ground.

Pre-flighting is simple. Climbing onto the wing with the flaps up and canopy closed however, is not. Enter the ‘take-a-run-at-it-and-leap-onto-the-wing-without-sending-your-foot-straight-through-the-fabric’ method. Once on the wing, the bubble-canopy is easily opened and slides back to reveal the tandem cockpits, painted all-black with bucket seats (which are incredibly comfortable).

The instrument panel is relatively uncluttered, however it does take a few minutes to familiarise oneself with where everything is in the cockpit... Mags on the left, Master near the left knee, trimmer near the left hip, lights near the left elbow, throttle and mixture on the left, along with the brake lever. Carb heat below the canopy frame on the right, starter to the right of the panel, compass between the legs, flaps by the right knee, and of course, a stick as well.

It is equipped with dual controls, so the rear cockpit is similar to the front, and includes another set of Magnetos switches.

Checking the controls during the pre-flight, you will immediately feel how light the ailerons are. It almost feels as if they aren’t connected to anything, and are just flapping around on a very well-oiled hinge. The main differences between this and a Cessna 152 for example, is when it comes to the engine. Priming for start is... different. The pilot operating handbook has a very complicated explanation of how to prime it. Once at the aircraft, it’s actually quite straight forward.

Climbing into the cockpit is like stepping back in time. First impressions are that it’s a small cockpit, as it is quite narrow, but once seated, it is surprising at how much elbow and leg room there is. And with the canopy closed, there is no sense of being trapped, or boxed-in. And there’s nothing like tilting your head back, and seeing a clear blue sky through the top of the canopy.

Ask anyone who has flown a Chipmunk what they are like to fly, and the answer is likely to be a smile and something along the lines of “It’s such a well-balanced aircraft, and easy to fly”. And it is. In fact, the most difficult part of flying a Chipmunk, is strapping yourself in. The 5-point harness and I fought a gruesome battle for several minutes, and the harness almost came out on top. But I eventually managed to clip the straps in (it has a system where you need to push a button down, and twist the front part to allow the buckles to clip in).

Originally fitted with a cartridge starter, this Chipmunk is kitted out with a battery-powered starter motor. The Gipsy engine readily fires to life, and will purr away contentedly even when cold. Actually, no, not quite; it doesn’t purr, it growls and shudders like the rumbling stomach of a giant, so much so that the entire instrument panel becomes a blur due to the vibrations.

Taxi-ing requires a considerably amount of co-ordination initially. Being a taildragger, its ambition is to throw its unsuspecting pilots into a ground loop. But coupled with that is De Havilland’s peculiar braking and steering system. It is equipped with a semi-castoring tailwheel, and differential brakes that only kick in after a certain amount of rudder is applied. There is a single brake handle, much like a car’s handbrake lever, on the right hand side, where you set a certain amount of braking power. The more you raise the lever, the more brake is applied, and the tighter you can turn.

So taxi-ing becomes a case of setting the power, holding the stick back with your right hand, sticking your head outside to see where you’re going (but even with its long nose, visibility is quite good due to the narrow fuselage), keeping it going straight with the rudder, and controlling the amount of brake with the left hand. While literally a handful to use, this is actually an incredibly clever design.

The informative De Havilland Pilot Operating Handbook is full of helpful checks. The take-off checklist for example, reads something like:
Engine running? Yes! Ok, go fly!
Alright, it is really like that, but it is very basic.

But being such a simple and easy aircraft to fly, you can safely fly it by the “seat of your pants”; it tells you when it’s ready to fly, and when it’s ready to land.
Even so, I managed to find that it will rotate around 50-60kts, and while best climb is something like 65kts, it much prefers 70-75kts because of the extra cooling. Just remember that as you take power for the take-off, it will yaw to the right due to the anti-clockwise rotating propeller.

This is a machine where you strap it to your back and become one with it. With the incredibly light ailerons, banking is almost as easy as thinking “Go left”. It requires little rudder input in flight, but the rudder is responsive when you do use it.

Steep turns are a walk in the park, because the Chippie is so well-balanced and responsive. Stalls (with and without flaps), are docile. She gives plenty of warning as you approach the stall, and after the buffet the nose drops smoothly and she starts flying again. All of the controls remain responsive throughout the approach to the stall. If you look carefully at the fabric of the wings, you will notice it starts to ripple as the airflow separates during the stalls.

Spinning the aircraft isn't easy. And it has a modified tail section to aid recovery. But to get it to enter a spin to begin with, you really need to commit to it. The Chipmunk doesn't want to spin. But when it does, the entry is rapid, and after about half a turn, starts to stabilise, with a very low nose attitude. Recovery is through the conventional method (unload the wing/release back-pressure, and apply opposite rudder), and it will be on its merry way again within half a turn.

It will happily lap up whatever you throw at it, and cruise at around 90kts. Checking the fuel quantity in flight is as simple as looking at the gauge next to the filler cap on either wing. Perhaps the only downside to the Chipmunk is the fact that it is “more-ish”; once you have a taste, you want more and more, and won’t want to land.

And speaking of landing the beastie... People often say the likes of the Cessna 172 are equipped with ‘autoland’, and that (most) tail draggers are notorious for being feisty on take-off and landing. Well, fly the numbers (if you can find them in the book), and the Chippie will land itself. My very first landing in the Chipmunk was the first and only wheeler I have ever truly ‘greased’. Misjudge the flare during your 3-pointer? Not a problem; get the nose up and stall it down from a foot or two, and you will hardly feel a bounce. In fact, you could probably come in inverted with your eyes closed and your pants on fire, and the old girl will right herself to gently kiss the tar rubber side down.

If it isn’t already, I highly recommend that you add the De Havilland Chipmunk to the top of your “Bucket List of Aircraft to Fly”.