Open or enclosed? Our experts tell it like it is
Many microlight and gyroplane pilots train in cockpits that are open to the elements. Go back far enough in aviation history and there was a time when everyone flew in open cockpits. If, like most pilots, you haven’t tried open cockpit flying, you might wonder what it feels like and what are its advantages and disadvantages.DEGREES OF EXPOSURE
Aeroplanes in the Edwardian era often left their occupants sitting in the open without even a flat windscreen. Today’s gyroplanes, hang-gliders, powered parachutes and a few microlights also leave your body, or at least the upper half of it, exposed. You can get a similar experience in conventional aircraft with a high wing by leaving one or both doors off. (And a few low-wing aircraft, like the Rallye-Koliber can be flown with the canopy slid back.)
Unlike the Edwardians, you will still have a windscreen in front of you. More conventional open cockpits like those in the Tiger Moth can have curved, flat or three-sided windscreens. These can come back to surround the pilot or be positioned only in front. The sidewalls of the open cockpit can be high – to the pilot’s shoulders, or low – down by the pilot’s waist. They can have an upper edge that is curved or straight. The cockpit rear can be as high as the pilot’s head or lower than his shoulders and might be embellished with a streamlined headrest. There is a lot of variation. FIRST EXPERIENCEOpen cockpits take some getting used to. The first time you fly in one may literally take your breath away and overwhelm you with noise and various distracting sensations. If you have to be trussed up in a flying suit, Irvin jacket, scarf, helmet and goggles you might very reasonably wonder why pilots talk about the freedom of open cockpits.Persevere, though, and you quickly tune out the distractions. Then you will discover what generations of pilots have known – that nothing beats open cockpit flying, especially for short flights in clement weather.SEEING OUTOpen cockpits give you a better view of the outside world. Even clean canopies cut down the amount you can see and they don’t stay clean long. By the end of a summer flight they will have a coating of crushed insects and a microscopic layer of oil mixed with dust. This can be a real hindrance when landing into a setting sun.Most pilots have experienced the sudden blindness of landing in rain when the rain stops streaming as you slow down and suddenly becomes raindrops. Open cockpits produce fewer blind spots because there’s no structure in the way. Furthermore, you can lean out the side for a better view while taxiing or coming in to land.In WWI the SE5a at first had a closed cockpit. Pilots felt it stopped them seeing ‘The Hun in the sun’ and it was discontinued.RAIN
If you are riding a motorbike in rain, the drops hit exposed areas of skin like little stinging pellets. This doesn’t happen in open cockpits with a windscreen. The water reaches you, but as a steady dampening effect rather than in stinging drops. In light rain you remain surprisingly dry, although you might find water streaming down the sides and dripping onto your knees from a seam in the cockpit wall.OPEN IS SIMPLER
Cockpit canopies have to be slid back or swung open to allow access to the cabin. They need hinges, runners and locks. Open cockpits reduce weight and complexity, because there is nothing to close and nothing to lock. However, the windscreen and open part of the cockpit does need to be carefully designed. Some open cockpits, like those in the Tiger Moth, still need to have doors fitted. The cockpit edges often need to be padded to provide protection in a crash.BETTER IN A CRISIS?
If a catastrophic engine failure shoots oil everywhere, much of it may go over the windscreen, and in a closed cockpit the pilot will be unable to see out. Open cockpit windscreens get coated too, but you can see round them. It’s unlikely that much of the oil will reach your face or goggles.Open cockpits also make it easier to escape in a crash, especially if the aircraft ends up on its back and there’s a canopy that has to be slid back or opened outwards. On the other hand, closed cockpits do provide protection. A bird strike can result – and has resulted on occasion – in a large struggling creature suddenly arriving in an open cockpit.FATIGUE
Most open cockpits are unheated and some are windy and full of draughts. The effect on a long flight can be surprisingly tiring, to the point where control of the aircraft can be compromised. The Tiger Moth’s cockpit is, for instance, poor at shielding its occupants’ shoulders and upper arms, which get a cold battering. Some cockpits generate a lot of wind noise from the air flow around the pilot’s head. Many fail to protect the top of the head, so that, for instance, the strap for retaining the headband of a David Clark style headset is buffeted continuously by slipstream. Most open cockpit pilots will have found their faces so frozen after a winter’s flight that they have difficulty enunciating words on the radio. There is little doubt that a closed cockpit is more comfortable in winter. Having said that, many pilots will remember the discomfort of queuing on the taxiway to depart from busy summer fly-ins when the air vents are hopelessly inadequate and the doors or canopy could not be opened. A few cockpits in convertible aircraft like early Pitts Specials and the JodelD9 are actually noisier closed than open, because of engine noise reverberating around a closed box. BETTER CONTROL
Despite the fatigue of extended open cockpit flying, one of its advantages is better control of the aircraft. You feel side winds when the slip ball goes off centre, and turbulence when the aircraft is about to stall. There is undoubtedly an enhanced ‘feel’ from wind-on-face in addition to ‘seat of the pants’ (at least, there is once you get used to flying in the open). The ability to lean over the side already mentioned can also enhance control in a difficult approach or when taxiing.AERODYNAMICS
Open cockpits create drag, cutting airspeed; they can also cause local turbulence that affects the flying qualities of the aircraft by reducing effective airflow over the tail surface and inboard area of the wings. However, some enclosed cockpits also cause aerodynamic problems. Careful design of open cockpits can stream the airflow so effectively that they create negligible drag; these cockpits will also be less noisy and draughty and the pilot may not need a helmet or goggles. It is, though, difficult to design a low-drag open cockpit without giving the pilot a small aperture, with the attendant complications of doors to allow entry and exit.The turbulence in an open cockpit can be quite marked. Occupants can find themselves being buffeted about by wind in a poorly designed cockpit. Let go of a piece of paper in a Piper Cub with the door down and window up and it will be blown all around the cockpit by invisible currents of swirling air before finding its way out.HELMET, GOGGLES AND OTHER GEAR
One disadvantage of flying ‘open’ is having to wear a helmet and goggles. With goggles you are still seeing the world through a screen of Perspex and goggles introduce blind spots. The RAF WWII style goggles look the part, but you might find you get on better – especially if you wear glasses – with skiing goggles. Wind in the hair may be romantic, but it’s also rather uncomfortable, which is why most people wear a cloth or leather helmet. In the early days, pilots stuffed cotton wool in their ears before donning the helmet, but today most are too concerned about going deaf to rely on something so ineffective, and wear a modern headset with proper ear defenders, perhaps supplemented with ANR.A hard hat safety helmet with visor is worn by most microlight pilots. It’s very comfortable, but won’t suit traditionalists. Modern boom mikes have replaced the discomfort of facemasks made from rubber that had to be clamped over the mouth. Facemasks, if you must have them for authenticity, can be left dangling and only clamped to the face and switched on when you want to speak to someone…but don’t expect passengers to cope with this.Thermal suits are extremely effective if your body is going to be exposed. Otherwise, jeans and a sweater are fine. You ought to wear Nomex fireproof flying overalls and leather gloves because both can save your life in a fire, but also to keep warm. Irvin jackets are bulky and only really necessary in exceptionally draughty cockpits like the Tiger Moth’s. Many open cockpits demand a long scarf as a way of keeping draughts from stealing their way down the back of the neck. Wool is fine, but silk works surprisingly well and isn’t so itchy. In winter your feet can get very cold and fur lined boots may be necessary. In some cockpits, tucking trouser bottoms into socks ‘plus-four’-style can stop draughts coming up your trousers.EXAMPLES
The Tiger Moth is the open cockpit that many people first experience. It has side doors that can be lowered to help you climb in and then closed to keep out the worst of the wind. The three-paned windscreen helps divert airflow to some extent.However, the cockpit is noisy, draughty and Practical Aviation Open cockpits terribly cold in winter.The Stampe’s open cockpit is considerably better, because the designer tried many different shapes and sizes of windscreen before he was satisfied. The B�cker Jungmann’s is even better.Turbulents (and the similar JodelD9) have curved windscreens that extend above the top of the pilot’s head. The rear of the cockpit (i.e. the bit behind your back) comes higher than the Moth and Stampe’s to about shoulder height. Even though the sides are actually quite low, this arrangement gives very good results, but the pilot does have a much larger area of Perspex to look through. You can comfortably fly a Turbulent with just ear defenders and without a helmet or goggles in summer weather. Early Pitts Specials had surprisingly comfortable open cockpits, but you do need a helmet and goggles. OPEN DOOR FLYING
Most aircraft that can be flown with the doors removed are noisy and uncomfortable. The Piper Cub has a door and window on the starboard side that are split horizontally; you can swing the window up and clip it to the wing and lower the door in flight. This improves the view downwards but is uncomfortable and noisy, especially for the occupant of the rear seat, who really needs a helmet and goggles. It also robs the aircraft of perhaps 5mph cruise speed and 100fpm climb rate. Reasoning that part of the noise, wind blast and lost performance must be drag from the dangling door and window, pilots have tried flying with them removed altogether – it helps but only a little.The Remos and Cessna 150 and 172 (among others) can be flown with the doors removed. All three suffer from lost performance and cockpit discomfort, but the Remos is relatively unaffected, probably because it is better streamlined to begin with.OPEN CANOPY FLYING
The Rallye and its later replacement, the Koliber, have canopies that can be slid all the way back in flight. Please note, though that most aircraft with sliding canopies must not have them open in flight – you must check the Pilot Operator Handbook. Attempting to open canopies that aren’t cleared can affect the aircraft’s controllability and there is a risk of losing the canopy altogether and it striking the tail on its way aft. Some military training aircraft also allow limited canopy opening in flight. Indeed, it was recommended to slide back the canopy in some WWII fighters to aid visibility when approaching to land.Aircraft with tandem seating manage quite well with sliding canopies, although there is some loss of performance, wind noise and discomfort. However, the Rallye and others that seat occupants side-by-side have cockpits that are too wide to be adequately screened. They are too noisy and uncomfortable to leave the canopy open for long; you certainly wouldn’t want to fly a long cross-country with the canopy slid back.CONVERTIBLES
Some aircraft, like early versions of the Pitts Special and several home builts, like the Taylor Monoplane and the Turbulent, are designed to be convertible. The Tiger Moth and Stampe both have convertible cockpit variants (the Moth’s is designed for WWII training in Canada, where students faced extremes of hot and cold). The idea is to have a permanent windscreen and a canopy that can be left on in winter and left off altogether in summer.CONVERTING YOUR AIRCRAFT
Successful conversions of aircraft with side-by-side seating to open cockpit are rare. A few do exist, for example the WACO currently in production has an open passenger cockpit that holds two. The Robinson Redwing and Tipsy Trainer were both designed with side-by-side open cockpits.If your aircraft is a single-seater or has tandem seating, it ought to be possible at least in theory to convert it to open cockpit. You can’t just leave off the sliding canopy, though (unless the POH allows it). First you will need to apply to the LAA or CAA for a modification. One Tipsy Nipper owner is currently going through this procedure. It has been facilitated because the first Tipsy Nipper is known to have flown with an open cockpit – precedent helps.However, the prototype Nipper had a low fuselage behind the pilot, reaching about one third way up his back. Experiments with the much higher rear fuselage in today’s version of the aircraft have run into difficulty. With a windscreen similar to the one in the prototype, the aircraft’s stall speed rises by 10kt and there is a considerable loss in elevator power. The addition of side screens is currently being tried, with some success, but it may be necessary to convert the rear fuselage – major work.Converting an aircraft from closed to open cockpit is far from straight forward and can completely alter its flying characteristics. However, take comfort should you lose your canopy in flight – the vast majority of such incidents end in a safe, controlled landing.
