One surefire way for airplane makers to get a lot more performance out of their existing designs is by adding a turbocharger. It’s hardly a new approach. It’s been popular since the 1960s. And just in the past few years Columbia, Mooney and Cessna have all introduced turbocharged models, all based on good-selling existing airplanes. So it was no surprise when Cirrus, which had in fact been openly talking about the possibility for a while, pulled the trigger on its very own turbo project, launching the SR22 Turbo Charged at AirVenture last summer.
Fans of Cirrus’ iconoclastic reputation will be happy to learn that the company somehow managed to change the way such programs are done. While Cirrus took a highly unusual (maybe unprecedented) approach, like every other controversial path they’ve tread-think parachute; think flat panels; think The Jet by Cirrus-there were good arguments in this case too for why it made sense to go outside the box to get things done.
Of course, the conventional way of developing a turbo model is to simply (okay, it’s not really simple at all) bolt on a certified turbocharged version of the naturally aspirated engine already on the airplane and make the necessary airframe changes, if any, to accommodate the increased speeds, altitudes and weights. In the case of four of the current (or emerging) production turbocharged airplanes, the Cessna Turbo 182 and 206, the Columbia 400 and the Mooney Acclaim, the airplane makers went with just that formula and came up with impressive performance increases. The Columbia 400 and the to-be-certified Mooney Acclaim can do around 235 knots true at 25,000 feet.
In developing its turbocharged model, however, Cirrus decided to modify the naturally aspirated engine it was already using on the airplane. So it partnered with aftermarket turbo mod house Tornado Alley in developing the turbo system, which earned an STC for it last fall.
The STC approach had risks: Would the airplane fly well enough at altitude to not need airframe changes? Would Continental honor the warranty on its very expensive engines given the modifications? And would the modification do everything, or at least most of everything that Tornado Alley promised?
The lure of the potential benefits of the STC approach apparently won out. One of those claimed by Cirrus is highly unusual and deserves mention. The company has all along said that by going the STC route on the turbocharger, owners would have the option of removing the turbocharger at some later point if 100LL avgas ever disappears without there being a suitable replacement, a scenario that Cirrus apparently believes is more likely than most other industry observers.
According to Cirrus cofounder Dale Klapmeier, the “engine warranty does not change” for the turbocharged airplane. “There have been discussions between Cirrus and TCM on the subject,” Klapmeier said, but the bottom line is “that warranty claims are made just like every other Cirrus SRV, 20 or 22, and assuming they are a valid claim, things get corrected.”
Be that as it may, the STC approach has several far less theoretical advantages, including lower developmental costs, easier certification and a faster route to market. And the Tornado Alley installation offers greatly reduced engine management. As I found out on my flight, while the SR22 Turbo Charged isn’t a single-lever airplane, it’s about as close as it can get with two levers.
The turbocharging package includes a built-in, four-place oxygen system by Precise Flight; we used the nice Precise Flight silicon masks with built-in mics. There’s also another pair of masks, without the mics, for the backseat passengers. And four nasal cannulas, which lower oxygen consumption considerably, are stand-ard too. The system is easy to use. A single switch activates the flow of oxygen in the airplane, and an LED status board keeps you apprised of the remaining supply and even alerts you to when oxygen is required. No one likes masks or cannulas, but short of a pressurized system, this is about as good as it gets.
One downside of the turbocharged airplane is that because of space limitations under the cowl-the cowl is unmodified- you can’t get it with air conditioning. A mitigating factor is that the airplane climbs to cool air so fast, you might not miss the lack of A/C as much.
The other very important part of the system is the new Hartzell three-blade composite propeller, certified just last summer, which represents the second generation of composite design from legendary prop maker Hartzell. The new prop boasts a number of improvements over the first generation and is a natural on the SR22 (turbo or not). The blade material is now a combination of Kevlar and carbon, as opposed to the earlier all-Kevlar blades, allowing for a thinner blade section at the tips, greatly improving efficiency and even rivaling metal blades, which can be made quite thin at the tips. The co-molded steel shanks have better retention qualities than those on the first generation models, so they don’t need secondary fasteners (bolts and screws on the previous model). Of course, the obvious advantage to the new prop is that it greatly cuts weight-the blades are 30 percent lighter than metal blades and overall the prop saves 14 pounds. But from my point of view the best part is that it really cuts down on vibration. The difference is very noticeable from the cockpit. With the Kevlar and carbon fiber prop, the airplane seems much smoother, especially on takeoff and climb-out, and the noise signature seems different too, smoother and slightly quieter, as well.
Like everybody else, I’d been aching to fly the new model since Cirrus unveiled it at AirVenture last summer, but the company was so busy certifying it, it wasn’t until the AOPA Convention in Palm Springs that anybody got the chance. It was, in short, worth the wait.
I’ve been flying SR22s of every description for several years now; I’m currently flying G2 and GTS versions with PlaneSmart, a Texas shared-ownership company. Non-turbocharged SR22s feel pretty familiar to me, so I was curious to see just how different the new model would seem and how difficult it would be to master whatever new operating procedures would be required.
As it turned out, there was almost no challenge to it at all.
It was a beautiful early November morning in the Low Desert of Southern California on the day when I went flying with Cirrus demo pilot Steve Noldin. To get away from the insanely dense air traffic at Palm Springs, we flew out of Bermuda Dunes, a few air minutes to the east. It was only slightly less insane there. Our mission was to see just how the airplane flew up high, really high, so we wasted no time at the lower altitudes I already knew all about. After all, there is no airframe difference, and because the engine is turbonormalized – meaning that the turbo keeps ambient pressure as you climb – there’s no increase in performance at sea level, except for the added acceleration you get from the prop.
Inside the cockpit, the engine controls are identical. Even the instruments are the same, with the exception of an additional set of parameters on the engine page of the Avidyne EX5000 multifunction display that shows turbine inlet temperature (TIT), in addition to EGT and CHT. There are the oxygen system ports and display and control, but the overall look and feel of the cockpit won’t startle any Cirrus pilot.
Operating the airplane, in terms of levers and gauges and masks, won’t take much additional training, either. In many ways, the turbocharged airplane is easier to fly than the normally aspirated one, though the risks and challenges of high-altitude flight shouldn’t be underestimated. Neither should pilots ignore the differences in weather to be encountered flying in the mid-teens to mid-20s. The planning challenges, for preflight, weather avoidance, winds and fuel, are different at those altitudes. Cirrus recognizes this and says that it focuses on many of these subjects in the transition course it offers for the Turbo.
You lean the mixture slightly for taxi and advance it again to full rich before takeoff. Unlike on some turbocharged models, the maximum manifold pressure in the modified IO-550N in the turbo is ambient pressure, so power management on takeoff is simple. Just push the power lever full forward and off you go. You will note on the engine page (which is also shown on the PFD) that the fuel flow will be through the roof, around 34 gph. After the initial climb you can pull that back to 30 gph and watch the airplane skyrocket. Because it can maintain max power as it climbs, this airplane, unlike non-turboed models, can continue to show high rates on the VSI even as it moves through 7,000 feet and above.
In a normally aspirated Cirrus, or any other non-turbocharged airplane for that matter, once you get much higher than around 6,000 or 7,000 feet, the lack of air starts to cut down on the airplane’s performance, reducing rate of climb substantially. Not with this airplane. We watched the percentage of power on the EX5000 stay right up near 100 percent throughout our climb almost all the way up to 25,000 feet, an impressive display of the turbocharger’s capability.
Because we step climbed in order to check performance at different intervals along the way, I didn’t get the chance to see how long it took to climb to the airplane’s ceiling of 25,000 feet, but it’s easy enough to estimate that at an average of close to 1,000 fpm for the entire climb-much greater than that down low and slightly less than that up higher-we’d be looking at between 25 and 30 minutes from sea level to FL 250.
Engine management during climb was easy. Keep the mixture at full rich (34-36 gph)-yes, that’s a lot of fuel-and 120 to 130 kias and the engine stays very happy, with CHTs (which we used as an easy reference for engine temperature) staying close to or lower than temperatures in the non-turboed model, even in climb. As I said, that is a lot of fuel, but then again, you’re climbing so much faster in the turbo-we saw rates in excess of 1,000 fpm through the mid-teens-you get up to altitude so fast it’s worth the expenditure. You can lean for the climb, but you lose much of the turbo’s advantage in doing so. While the turbocharged airplane doesn’t have any more fuel in the wings than its predecessor, thanks to the higher speeds, its range (around 840 nm) is practically speaking about the same as its non-turboed counterpart.
The Tornado Alley installation is a twin turbo, twin intercooler system, and you get the added bonus of GAMInjectors, a fuel metering system that Cirrus claims keeps cylinder head temperatures at optimum values. Based on my flight, the claim is solid. Not only were the CHTs well shy of 400 degrees, but they were remarkably well balanced, with the spread between the hottest and coolest cylinder seldom being more than 40 degrees. Cirrus claims that the inherent design of the IO-550 when mated with Tornado Alley’s turbocharger system is a more efficient, cooler running system than purpose-built turbocharged engines.
At cruise, engine management is even simpler, and the fuel flows, as promised early on in the program, are better than they are in the normally aspirated airplane at much higher true airspeeds. Pilots who fly the SR22 love the “lean assist” feature on the Avidyne MFD, but in the turbocharged airplane, it’s not necessary. Cirrus’ technique for leaning is, regardless of the altitude, simply set the power to 2500 rpm and the fuel flow for 17.5 gph and you’re done. It takes all of five seconds, and there are only two numbers to remember.
| The airplane flown for this report was one of the first certified with the new Tornado Alley turbocharger system, earned under a supplemental type certificate (STC), which is an add-on package ($59,995) installed into the SR22 at the Cirrus factory in Duluth. The most typical SR22 package comes with the Avidyne Entegra flat-panel avionics system, which includes 10.4-inch diagonal primary flight and multifunction displays, S-Tec 55X two-axis autopilot with GPS steering, XM satellite weather, L3 Skywatch traffic advisory system, TAWS terrain avoidance system, C-Max electronic approach charting, L3 Stormscope and Electronic Engine Monitoring. Also stand-ard with the Turbo Charged is a Precise Flight built-in oxygen system. All specifications are from the manufacturer. |
While it gets its best speeds up high, the turbo makes a lot of sense down low at non-oxygen-required altitudes from 9,000 to 12,000, where you can take advantage of the thinner air and less-traveled airways and cover a lot of ground fast. At 12,000 feet Cirrus advertises 194 knots true, but we were getting just a tick under 200 knots at that altitude, running at 2550 rpm and 17.5 gph. In a non-turboed airplane running at best power and optimum altitude, you’d be looking at around 180 knots and nearly 20 gph.
The airplane’s top cruise speed comes at 25,000, where the example we were flying was truing 215 knots, again at 17.5 gph. At that speed, the airplane can cover a lot of ground, making up to a large degree for the high fuel consumption on the climb. And it’s nice to note that the handling characteristics of the SR22 at 25,000 feet were fine. There was, in fact, no noticeable difference in its handling manners at all, though we didn’t explore much of the envelope on my flight.
On my flight the airplane did better at every altitude by a few knots or more than Cirrus advertises. And Cirrus makes a very good point when it says that the speed at 25,000 feet isn’t a good measure of the capabilities of the airplane. They contend, and I agree, that few pilots will be regularly operating these airplanes-Cirrus’ or its competitors’-at FL 250. Instead, they’re likely to frequent altitudes from 10,000 to 20,000 feet. And at those levels the Cirrus is very close in performance to its rivals while burning less fuel and running very cool, whereas up higher and burning much more fuel, its rivals are substantially faster.
With the Tornado Alley system installed, the engine’s TBO remains the same, claims Cirrus, at 2,000 hours. And it’s not hard to believe that it could make TBO. On my two-hour flight the airplane ran very cool the whole way with the manifold pressure never getting above around 30 inches of pressure.
The biggest downside of Cirrus’ strategy of sticking with the original SR22 airframe and adding a third-party turbocharger system is that the resultant higher-fuel burn airplane doesn’t have any more fuel than the original, a total of 81 gallons usable. Consequently, while the range is certainly workable-840 nautical miles at 200 knots-there are a lot of pilots who will want more. And the endurance at high-power cruise, 3.9 hours plus a 45-minute reserve, is well within the limits of many pilots, myself included, who might find themselves wishing they could get a few hundred miles further toward the destination without needing to stop for fuel.
Once you’re down low, the Cirrus performs like any other non-turbo SR22, and it offers the same kinds of creature comforts, one of, if not the most comfortable cabins in its class, a great avionics package, luxurious leather and XM satellite weather and entertainment channels. And when it comes to performance, the SR22 Turbo Charged is going to be very competitive with the Columbia and the Mooney at between 10,000 and 12,000 feet, delivering around 200 knots on just 17.5 gph
Because it comes as an option, the $59,995 price of the turbo package is added into the price of the non-turbo SR22. The limited edition SE turbo sells for $532,000, and standard models with the turbocharging package will sell for around $510,000 very nicely equipped.
How popular will the turbocharged model be? Historically (at least within the past 30 years or so) newly introduced turbocharged airplanes sell in substantially higher numbers than their normally aspirated counterparts. Indeed, sales of the Columbia 400 dwarf those of the non-turboed 350. In fact, Cirrus planned to deliver more than 40 turbocharged SR22s in December of 2006 alone, and Dale Klapmeier told Flying that it could deliver as many turbocharged airplanes as demand warrants from that point on.
For more information about the SR22 Turbo Charged, visit www.cirrusdesign.com
