Article from Today's Pilot

The following article is reprinted with permission from the Sept 2001 edition of "Today's Pilot" magazine, published in the UK. Many thanks to Today's Pilot for allowing us to reprint the article here.

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CIRRUS SR20

Fast, efficient and comfortable, the Cirrus SR20 is definitely a general aviation aircraft for the 21st Century. Dave Unwin is impressed.

There are times when being the editor of Today's Pilot is perhaps not all it's cracked up to be. Difficult designers, subversive sub-editors, awkward advertisers and the ever-present threat of the next deadline can all combine to take the shine off of what is actually quite a good job. Still, it can have its compensations, such as flying a brand-new Cirrus SR20 high over Lake Constance on a spectacular spring evening! With Johann 'Baron' von Riemeishausen in the seat alongside me and a Zeppelin passing overhead, we raced down the runway at Friedrichshafen and up into the cool evening sky for an aerial view of the Austrian Alps. As much as I enjoyed my flight with the 'Baron' it actually left me with more questions than answers and I was eager to get my hands on another Cirrus in order to perform a more qualitative evaluation.

My next chance to fly the SR20 came a couple of months later, when Mike Glaser flew his immaculate aircraft into Conington on a very hot July day.

Before we went flying, I had a good look around the machine and was extremely impressed, both by the very high build quality and by the amount of thought that had gone into its design. One of the first things that struck me during the walk round was the width of the wheelbase. For a four-seat aircraft it is incredibly wide. It is also very low maintenance. Both the mainwheels and nosewheel struts are of composite construction, making for a very simple undercarriage. As befits an aircraft designed to go places at a good rate of knots, all three wheels are closely spatted.

The relatively high aspect-ratio wings were also interesting as they feature drooped leading edges at about two thirds span. The logic behind this design is that it keeps this part of the wing (and the ailerons) flying after the inboard section has already stalled. I was also interested to see that the wing features two sets of stall strips - one set relatively close to the fuselage and the second set situated just inboard of the drooped leading edges. Again this is to ensure that the inboard section of the wing stalls before the drooped section. Large span, single-slotted flaps complete the wing. Although the airframe is predominantly constructed of composite materials, I noted that Cirrus has wisely decided that the parts of the aircraft most vulnerable to hangar rash, such as the ailerons, flaps, elevator and rudder, should all be made from aluminium. The engine, a 200hpTeledyne-Continental IO-360 air-cooled flat six, is quite tightly cowled and features a pair of very long, tuned exhaust pipes. In common with many other aspects of the SR20, the propeller is also slightly unusual.

It is a three-blade constant speed unit made by Hartzell, with blades that feature an intriguing swept-back leading edge.

While moving around the fuselage, I was particularly impressed by the door to the baggage bay, as it features a very simple - but much appreciated - feature, a pocket built into the door. This is absolutely ideal for holding a litre bottle of oil, a fuel strainer and other pre-flight paraphernalia. Like all great ideas it is brilliantly simple, and I couldn't believe that it hadn't been thought of before. Another great idea is the small window set into the roof of the cabin just forward of the cover for the CAPS, as it lets light into the baggage area.

Access to the cockpit is good. There is a grab handle on either side of the fuselage, and a pair of steps just aft of the trailing edge complements these. I was rather surprised to see that the non-slip surface of the wing root walkway is white, although this may have something to do with keeping the temperature of the composite mainspar down. The doors open wide and are well-supported by gas struts.

Settling into the very comfortable cockpit, I was immediately struck by how 'car-like' it is. Someone at Cirrus Design has obviously made the connection that the kind of person who will buy a Cirrus Design aircraft almost certainly drives a fairly expensive car. Consequently, in many ways the cockpit resembles the interior of an upmarket motorcar (I was later to read that the interior is actually modelled on the BMW-5 series). The seats adjust fore-and-aft over a wide range, and a handy grab handle is situated above the windshield to help you pull yourself forward. The seat tracks are arranged in such a way that as the seats move forwards, they also angle upward slightly. This ensures that shorter people are positioned slightly higher as they move the seat forward. A nice touch, and doubtless one much appreciated by anyone who is 'vertically challenged'. The backs of the front seats recline, while the backs of the back seats can be folded forward to make it possible to carry bulky objects that extend forwards from the baggage bay. The cabin is very large for a four seat aircraft, with plenty of room for four adults. Each occupant is provided with a headset socket, and even a cup holder, while underneath the armrest between the two front seats is a very useful storage compartment.

Having adjusted and locked my seat and fastened my harness, I began to familiarise myself with the instruments and controls. The most obvious feature is the very uncluttered panel, a product of clever design, and the use of side-stick controllers, of which more later. With a few minor exceptions, I thought the cockpit was extremely well thought-out. The instrument panel is dominated by the ARNAV ICDS2000 multi-function display screen in the centre, with the flight instruments situated on the left side of the panel and the engine instruments on the right. The main switch panel for the electrical services is situated directly below the flight instruments and consists of a row of large, user-friendly rocker-switches. Conversely, the main circuit breaker panel is less user-friendly, being situated to the right of the pilot's right leg, along with the parking brake and alternate air knob. Another feature that I didn't really like was the location of the fuel gauge. This is located on the centre console aft of the combined throttle/prop lever, and doesn't really lend itself to being incorporated in an ordered scan of the instruments. However, there is a low fuel light on the annunciator panel.

The centre console contains easily the most comprehensive avionics suite I have ever seen installed in a single piston-engined aircraft. Two immensely powerful Garmin GN430 GPS receivers are fitted, with number one coupled to the HSI and STEC 55autopilot and number two coupled to the ILS. Either can supply information to the ARNAV moving map display, and this can also display a wealth of other information, such as aircraft performance charts and checklists from the Pilots Operating Handbook. The ARNAV is also coupled to the BF Goodrich WX500 stormscope, which can detect lightning at ranges of up to 200 nautical miles. Communications are taken care of by a pair of Garmin GNS430 VHF transceivers connected to a Garmin GN 340 integrated audio system and intercom. A Mode C transponder and a marker beacon receiver, both also produced by Garmin, complete an avionics fit that wouldn't look out of place in a Lear Jet. Upon looking up, I also noted the cover for the CAPS deployment handle, which is located in the roof. More on this later.

Starting the engine is perfectly straightforward. Between the seats and to the left of the throttle is a rocker switch. Having pushed the mixture lever to 'fully rich' and the power lever fully forward, simply rock this switch backwards and hold, to prime the engine for four seconds, then click it forward to the 'boost' position. The power lever is then retarded until it is only open about an inch, and then the engine is started. A flick of the avionics master switch brought the awesome avionics on line and we were ready to taxi. By now, the temperature in the cockpit was rising steadily under the merciless glare of the midday sun and I couldn't help but observe that the well-situated cockpit air-vents weren't actually doing anything. Despite having a number of very useful automotive features, the Cirrus SR20 doesn't have an electric fan to supplement ram-air pressure, and on the ground it could certainly use one. Mike told me that it is possible to taxi with the doors open, but that he found it awkward to shut the door once strapped in. I was also surprised to note that the SR20 is not fitted with a direct-vision panel, as this would also have helped in lowering the cockpit temperature.

Taxying out to the active runway revealed very nice ground handling. The nosewheel castors so all steering is by differential braking. Fortunately, the SR20's toe-actuated hydraulic disc brakes have a nice progressive feel. At the run-up area we ran through the pre-take-off checks, and again a number of the SR20's innovative features revealed themselves. As mentioned earlier, the SR20 features sidestick controllers, so to trim for take-off requires the use of the 'coolie hat' electric trim switch on top of the stick as there are no manual trim controls. The control handles are mounted on tubes that are square and installed in such a way that an edge is on top. The correct take-off trim positions for both elevators and ailerons are marked on the box section tube, and it is a simple matter to motor the trims to the correct settings. Another interesting feature is the fact that the SR20 is fitted with a single power lever, which incorporates the functions of both the throttle and prop control levers. During the run-up checks the power lever is smoothly advanced until it hits a detent. At this point rpm should be increasing to around 2,000rpm until the lever reaches the detent, at which point it should reduce by around 100rpm. This indicates that the control link to the hydraulic constant speed unit, and also the CSU itself, are functioning correctly. Although approved for take-offs with the flaps fully retracted, Mike recommended setting them to the 50% (16 degrees) position. This is accomplished by moving the flap-shaped lever located at the base of the avionics stack to the desired setting. An electric motor then extends the single-slotted flaps until they are in place. Flap position is indicated by one of two yellow lights mounted coincident with the flap lever. When the flaps are fully retracted this is indicated by a small green light.

The rest of the pre-take-off checks revealed nothing out of the ordinary and I rolled out onto the runway and lined the aircraft up with the centreline. Having allowed the SR20 to slowly trundle forward a few feet to ensure that the nosewheel was straight, I smoothly advanced the throttle to the stop. As the power lever goes through the detent there is some resistance, requiring a positive increase in the push force for the power lever to travel to the full power stop. I would estimate that at our weight we were probably around 500lb below the maximum weight of 2,900lb and with a power-to-weight ratio of around 12 pounds per horsepower, acceleration was correspondingly brisk. Initially, the SR20 revealed a slight preference for the left side of the runway and small dabs of right brake were necessary to track the centreline until the airspeed started to build and the rudder became effective. As the ASI needle swept briskly through 65 knots, I eased the sidestick back and the SR20 leapt off the ground and settled into a brisk climb. Eighty knots was attained within seconds and I flicked the flap lever to the up position. The flaps retracted quickly with only a small change in pitch trim. At this point I did notice that I was applying a considerable amount of right rudder in order to hold the slip ball in the middle, and wondered briefly whether the aircraft would benefit from the addition of a rudder trimmer. Although Vy is attained at 84kts, Mike suggested that 95 would be better, for both visibility and engine cooling. As I increased speed, the requirement for right rudder reduced while the VSI continued to show a very healthy rate of climb. The electric trim for both pitch and roll works very well. I had read that, in common with many other electric trim systems, it was geared a bit high for precise trimming. However, I had absolutely no trouble at all. I think that the key to using such systems well is to simply 'blip' the switch momentarily in the appropriate direction. If you actually press and hold the switch, you will almost certainly over-trim.

Levelling at 3,000ft, I eased the power lever back through the detent and retrimmed. Whenever the power lever is set for full power the interlinked prop control ensures that the governor maintains maximum prop rpm. When the power lever is pulled back, the governor keeps the prop at max rpm until manifold pressure drops to around 24in-25in of manifold pressure. At this point the prop governor reduces rpm to around 2,200 - 2,400. With the SR20 trimmed out and the six-cylinder engine humming quietly to itself, the ASI needle swept inexorably around the dial until it settled on just over 150kts true. With a maximum wing loading of around 24lb/sq ft, the SR20 has relatively high wing loading, and this gave a rock-steady ride as we punched through some light chop. Indeed, although I know it's a cliché, the best way to describe the ride is that it really did feel as if we were on rails. Stability and control around all three axes is excellent. With the aircraft correctly trimmed, it is really more a matter of control pressures as opposed to control movements, although, particularly in roll, the aircraft responds with alacrity if you apply a large control input. A couple of steep 360 degree turns revealed excellent handling qualities that really required no rudder inputs to balance the turn. I was later to read that there is a spring interconnection which deflects the rudder when aileron is applied. Visibility all though the turn, and indeed throughout every stage of flight, is simply superb. The SR20 also displayed an interesting phugoid during the longitudinal stability check. Having released the stick from a trimmed speed of 140kts at 120kts, it only performed one very long, gentle phugoid before returning to the trimmed speed. As I was to note once again in the circuit, it is extremely speed-stable. Slowing down to explore the low speed side of the flight envelope took a while, as the SR20 is a very 'slippery', low-drag machine. Whether flaps are up or down, the SR20 is quite reluctant to stall, ample pre-stall buffet occurring before the warning horn sounds. I think it would be quite difficult to inadvertently stall an SR20. Even with full aft trim applied, holding the nose up required a considerable amount of back pressure, and it may well be that Cirrus Design have made a conscious decision to restrict up-elevator. It was also interesting to note that, even deep into the stall, the ailerons remained effective - clear testimony to the efficiency of the stall strips and drooped leading edge. One area that I would have liked to investigate further is the aircraft's behaviour with a contaminated wing. I know from flying sailplanes fitted with laminar-flow wings that even minor contamination by rain or even dead insects can have a significant effect on performance.

As we closed on the camera ship for the photo-shoot, the position of the power lever friction knob revealed itself to be less than satisfactory. However, the real problem was the actual power control lever. When flying formation, and particularly when turning in formation, quite minuscule adjustments in power can be required in order to hold station accurately. The problem of flying formation with two fairly disparate types was exacerbated by the detent for the Cirrus's combined throttle/prop lever. Unfortunately, the detent always seemed to be in the wrong place, which meant I invariably had either just too little or just too much power. However, this should in no way be taken as a criticism of the aircraft. It has not been designed for close formation work - it has been designed to transport four adults quickly, safely, efficiently and comfortably, and in these respects it excels.

The photo-shoot over, we broke away from the camera ship and set the SR20 up for the purpose it was designed for - going places. At 6,000ft the power lever was set to give 23in of manifold pressure. The interlinked prop control drew the prop rpm down to 2,500 for a percentage power setting of 74%. After adjusting the mixture control, fuel flow settled on 9.5 imperial gallons an hour, and having corrected the ASI reading for temperature and pressure the true airspeed came out at a very impressive 151kts. This means that, in still air, you are covering the ground at nearly three miles a minute and, let's face it, that's the way to get somewhere!

Of course, it is actually possible to cruise the SR20 nearly ten knots faster, should you deem it necessary. However, this requires the power to be set to 88% (24in and 2,700rpm) and fuel flow rises accordingly to nearly 11.5gph. Once we were established in the cruise, Mike delighted in showing me just a fraction of the capabilities of his aircraft's incredible avionics suite. First, he brought the stormscope up onto the ARNAV display, and we were both impressed to see it had detected and recorded lightning strikes at a considerable range. Then, having engaged the STEC autopilot, he simply hit the 'go to' button' and the SR20 obediently banked back towards Conington. But rather than simply take us back to the field, Mike had asked it to intercept the extended centreline for the active runway before turning onto the approach, and this it unerringly did while maintaining both speed and altitude with robot-like precision.

But why should the autopilot get all the fun? A firm push directly downwards on the 'coolie hat' disconnects the autopilot, and I resumed control and swept the SR20 gracefully around to position it to join on a downwind leg. As mentioned previously, the SR20 is a slippery beast, and care must be taken not to let it run away from you when the flaps are retracted, particularly as the maximum flap extension speed is a relatively low 100kts. However, once the air speed has slipped into the white arc and it is safe to extend the flaps, they really bite. You can actually feel the deceleration, and with full flap extended, even lowering the nose some way below the horizon failed to accelerate the aircraft. Mike had recommended a speed of 80kts in the circuit, reducing to 75 on short final, and the speed control is so easy that I had no difficulty in holding the speed exactly. A smooth, easy flare and the mainwheels rolled gently onto the tarmac. Flaps to 50%, full power and the SR20 surged back down the runway and up into the sky. The next circuit and approach worked out even better, and by retarding the power lever fractionally earlier the tyres kissed the numbers with the minimum of fuss.

Back at the parking ramp I selected the avionics master switch to 'off', pulled the mixture control to idle/cut off and the prop rapidly slowed to a stop. I have to admit to being hugely impressed by the Cirrus SR20 and would love to own one. Now I'm sure you're all thinking "he always says that" and it is true that when Steven Spielberg turns my book into a film, I'll buy a fleet of aircraft larger than many third world air forces! For moving four adults from A to B quickly, safely and comfortably, the Cirrus range of aircraft certainly takes some beating. I was also impressed by the relatively low price of the SR20. Indeed, bearing in mind the avionics fit and the CAPS, it really does represent extraordinary value for money. Cirrus Design continues to refine its already very impressive range and I am looking forward with a great deal of anticipation to testing what will quite possibly be the four seater of the future, the 230hp diesel powered SR21tdi. Watch this space.

Sidebar:

One of the features that makes the Cirrus stand out from its competitors is the Cirrus Airframe Parachute System (CAPS) which is produced by Ballistic Recovery Systems of Minnesota. Obviously, if at all possible I think most pilots would probably attempt to force-land after an engine failure. However, should the situation be clearly irretrievable (say after structural failure or an engine failure occurring over water or inhospitable terrain) then the Cirrus pilot has one more card to play. A firm pull on the T-handle mounted in the roof will ignite a small rocket mounted aft of the baggage bay, and less than four seconds later the Cirrus should be dangling in a stable, upright condition from a large parachute. True, a descent rate of around 1,800fpm will almost certainly result in more than a few bruises for the occupants, but at least everyone should survive. The system built by BRS for Cirrus weighs approximately 55lb and features a parachute canopy with a 55ft diameter. It is certified for use up to 134kts. BRS believes that the CAPS parachute could be successful under some circumstances at heights as low as only 300ft-500ft above the ground. The system has also demonstrated the ability to recover the SR20 from stalls and spins, even if deployed after one full turn into a spin. The Cirrus is the first production aircraft to be fitted with a BRS, although it is actually not a new idea. Indeed, some hang-gliders were fitted with relatively crude, hand-deployed emergency parachutes as far back as the late 1970s. The first ballistic systems, which were based around a charge similar to a 12 bore shotgun cartridge, began to appear in the early 1980s. However, rocket propulsion was clearly the way to go and all modern BRS units use small, high-energy rockets to pull the parachute canopy from its container. Ballistic Recovery Systems, Inc., has been selling these systems for nearly two decades, and has delivered nearly 14,000 systems, mostly to non-certified sport aircraft. Although a CAPS has not yet been fired in an emergency situation, around 140 lives have already been saved by use of a BRS.

CIRRUS SR20

Dimensions
Length	26ft 7.92m
Height	9ft 3in 2.82m
Wingspan	35ft 6in 10.82m
Wing Area	135.2sq.ft 12.56m2
Aspect Ratio	9:1

Weights and Loadings
Empty weight	1,950lb 885kg
Max AUW	2,900lb 1,315kg
Useful load	950lb 431kg
Wing loading	21.44lb/ft2 104.7kg/m2
Power loading	14.5lb/hp 8.82kg/kW
Fuel capacity	50 Imp gal 227 lit
Baggage capacity	130lbs 59kgs
Design 'g' loading	+3.8/-1.9g

Performance
Vne	200kts 370km/h
Cruise	160kts 296km/h
Stall	54kts 100km/h
Climb rate	920ft/min 4.7m/s
Service ceiling	16,000ft 4,880m
Range	800nm 1482km

Engine	Teledyne-Continental IO-360-ES air-cooled flat six producing 200hp (149kW) at 2,700rpm.
Propel	Hartzell three blade constant speed.
Manufacturer	Cirrus Design Corporation, 4515 Taylor Circle, Duluth International Airport, Duluth, Minnesota