Guy Leitch
One of the world’s most eagerly awaited piston single engine aircraft designs has finally arrived in South Africa. ZU-KTR is a long awaited Panthera, proudly owned by Bertus Kritzinger, a Free State trucker, and based at New Tempe in Bloemfontein.
Pipistrel have won many prizes for efficient planes and so the Panthera generated much excitement when it was announced at Aero Friedrichshafen in 2012. If it had been any other company, the claims would have been laughable.
The key claim was that the Panthera was going to manage, “four seats, 200 knots and 1,000 nm.” These were the magic numbers Pipistrel CEO Ivo Boscarol set as a challenge for his engineers in 2007. This was taken to mean a 200 knot cruise – on just 210 hp. Considering that the sleek Piper Comanche 400 cannot do that on 400 hp, many observers just quietly shook their heads and adopted a wait and see approach to the Slovenian plane builder’s aims.
Time passed and it seemed that Pipistrel were indeed having problems making their numbers come true when Panthera development was moved to a back burner. Then it was quietly announced that the engine had been increased from the original’s 210 hp to 260hp.
So the big question is – has Pipistrel managed to nonetheless create a 200 knot speedster that can comfortably seat 4 for 1000 nm?
Development
Founded in Slovenia by the charismatic and brilliant Ivo Boscarol in 1989, Pipistrel has always been committed to efficient aircraft. Significantly he has now certified the first electric trainer, the Velis Electro, built on the uniquely named Pipistrel Virus base.
After the Panthera’s launch in 2012 things went quiet. “The main reason it was held up was because Pipistrel was contracted by several governments, including the U.S. government, to convert their two-seat airplanes into unmanned aerial systems for surveillance use by the military,” the company said in a later announcement.
ENGINE OPTIONS
The Panthera was designed from the outset to have not just one – but three, different engine options: an all-electric version, an electric hybrid and a conventional internal combustion engine (ICE). Perhaps unsurprisingly so far only the ICE version has made it to market. However, in 2016 a Panthera mock-up received a hybrid-electric engine, being powered by either a 200-kW electric motor driven by batteries only, as well as by a 100-kW generator-only, and by both combined. In October 2021 Pipistrel announced that the hybrid version had completed the first phase of its flight test programme.
Pipistrel had originally specified the IO-390 because of its good its power-to-weight ratio and because it could burn Mogas (car petrol) . Except, in the end it couldn’t, as Lycoming said that the IO-390’s 8.9:1 compression ratio was too high for Mogas. So Pipistrel switched to the 260-HP IO-540-A5V4, which does allow Mogas. The extra 50 hp no doubt helped with the elusive top speed goals.
The IO-540 weighs about 100 pounds more and is longer. Pipistrel addressed the centre of gravity by adding additional length to the rear airframe. The extra power also helped with high density altitude operations. The max all up weight was increased by 210 lb to make up for the extra weight of the engine.
At the time of the engine change, Tine Tomažič, the Director of Engineering, said, “A lot of this decision was made because customers want good hot and high performance. We have lots of people coming from South Africa, from Argentina, from Mexico, from Colorado, places that would otherwise demand a turbocharger solution. But instead of going to a turbocharged four-cylinder, we decided to go for a normally aspirated six for maintenance and operational simplicity,’ he said.
ON THE GROUND
The Panthera is the low-slung sportscar of the air. Its commitment to a low profile is reminiscent of the iconic Ford GT40, which was only 40 inches high. To get this low, sleek look, the canopy is not far from horizontal and, like a glider, needs to be kept spotlessly clean if it is to be properly transparent, with minimal distortion.
Composite construction may be sleek, but it’s not necessarily lightweight. The 260 hp Panthera is now a 2,900 lb MAUW plane with a useful load of about 1,100 lbs. That makes it comparable with the Mooney Acclaim and 240 pounds lighter than recent Cirrus models – and even about 130 pounds lighter than the Diamond DA50.
Interestingly Tomazic said, “Fuel capacity remains the same, 220 litres (58 USG) because for the given mission, the airplane will not consume more fuel. We are targeting the same cruise speed of 200 knots true and the same 10.5 gph.”
Dimensionally, the Panthera is the smallest. It’s the same length as the Cirrus SR22, but the wingspan is almost three feet shorter. And even with its tall T-tail, the Panthera is nearly a foot shorter than the Cirrus. Notably, the cockpit is low and wide, but at 47 inches, still narrower than the Cirrus’s 49 inches. Once seated inside, the limited headroom makes it feel tighter than an SR22.
The cabin has two large gullwing doors on either side, and, for the rear occupants, an even larger gullwing hatch, similar to Diamond’s DA40. It’s surprisingly easy to step down into both the front and back seats.
Gullwing doors did not become popular because they let the rain in, and if the plane is lying on its back, may be impossible to open. Yet accident reports suggest that occupants being trapped after a crash doesn’t appear to be a real problem. Either planes don’t flip much or, if they do, survivors manage to get out okay. Further, the Panthera’s rear hatch doubles as an emergency exit – a glass-cutting hammer is provided. Gullwing doors opening in flight is another concern, because the door is likely to be ripped off and hit the tail. Pipistrel has addressed that with a robust closing mechanism that uses an over-centre lock.
Unlike the Cirrus, which has a long single-piece wing and thus has to be flown from the factory to South Africa, the Panthera has removable wings. The whole aircraft fits into a standard shipping container. Like composite gliders, the wings have overlapping spars that are mounted to the fuselage and each other with hefty steel pins with locks. Also like a glider, the controls use push rods for the ailerons and elevator.
Getting aboard requires stepping onto the wing. The flaps are about two-thirds of the span, so the wing walk area on both sides is protected with a solid surface. Technically, that makes that section a split rather than semi-Fowler flaps.
The flaps and the gear are electric, driven by rods and tubes. The gear backup is a crank located in the centre console between the two front seats. It’s a pity they could not make a gravity free-fall system.
The Panthera has a whole-airframe parachute as standard, but unlike the Cirrus, it is not required as a condition of certification, and so may not need expensive 10-year servicing.
The Cockpit
Getting in is easy. From the wing you can step onto the cockpit floor and use a handgrip to lower yourself into the seat. But getting out requires considerable upper body strength to pull yourself up with one hand.
ZU-KTR has a two-display version of Garmin’s G3X Touch, driven by a GTN 750 with autopilot. While this provides plenty of capability, some buyers may view it as a step down from the G1000 NXi found in new Cirrus and Diamond models. Because of the Panthera’s smaller panel, the G1000NXi may not fit.
ZU-KTR does not have Garmin’s ESP envelope protection, even though it is available for the autopilot and is a planned addition. And while the NXi/GFC 700 in the Cirrus and Diamond may eventually get Garmin’s Autoland option, it’s not contemplated for the Panthera. ADS-B is via the GTX 345 transponder.
There is a secondary battery to power an essential bus that includes the primary flight display and one of the two ADAHRS units. Additional backup is provided by a Mid-Continent SAM MD302, plus the Touch display has reversionary capability for primary attitude.
There’s plenty of space for maps, engine monitoring and the primary flight display. There is a clever sub-panel that shows the cabin air status. Push the test button and it shows the status of gear, flaps and fuel remaining as a percentage.
IN THE AIR
Taxi is smooth, thanks to the beefy trailing link gear. The bottom-hinged rudder pedals are comfortable to use and the Beringer toe-brakes effective. Thanks to a steerable nosewheel, taxiing is easy and accurate.
The view forward through that long sloping windscreen isn’t great. The instrument panel glareshield is higher than a C210s and the seating position is laid back. This means you can’t easily see beyond the right side of the nose when taxying. And when turning from crosswind onto downwind in the circuit, you won’t easily see traffic coming straight in to the downwind leg.
Having plenty of glass makes the cabin hot on a sunny day however you can taxi with the gullwing doors open, and this provides more than enough cooling from the prop.
Unlike the Americans, the latest European designs have control sticks, which provide a more precise, uncompromised feedback.
Given that it was designed for speed – the question is how does it compare to its competitors? Its natural competitors are the similarly built-for-speed Mooney Ovation, the sleek Diamond DA50 RG, and the 315 hp Cirrus SR22.
Pipistrel elected to avoid the weight and complexity of a turbocharger and the Panthera is faster than the turbo Cirrus SR22T all the way to 18,000 feet. The Panthera is about 5-knots faster than the normally aspirated SR22 G6. However the 310 hp turbo Mooney Acclaim Ultra is still the fastest.
Pipistrel is not just about speed, it’s about efficiency. For this, the measure is how far a plane flies on a pound of fuel. Here the Panthera easily beats both Mooney models but with its turbocharged diesel, the Diamond DA50 RG is the efficiency champion.
The Panthera has about 1100 pounds of useful load and the CofG range is a generous 9 inches, so loading it out of limits takes effort. As a sample weight and balance, with 375 lbs in the front seats and 300 lbs of pax in the back and 100 lbs of bags, the plane is at gross and still within CofG.
The Panthera gets airborne at about 65 knots with a moderate but not over-light pitch force. During initial climb, the restricted forward visibility is no worse than over the long nose of our Saratoga. The Panthera climbs well, with, at best rate Vy, 1600 fpm available initially. A cruise climb at 130 knots still yields a 600 to 800 fpm climb.
It’s all about the cruise numbers. And impressively the Pipistrel beats its book figures. On a typically hot ISA +30 day, at 8000 feet, it delivered 184 knots true on 13 GPH at 65 percent power. At 55 percent, it cruised at 174 knots on about a gallon less.
The stall isn’t as benign as say a Diamond DA40. If held deep into the stall, it will drop a wing hard and fast.
Pitch stability is lower than its competitors. If the nose is high and the stick released, the Panthera takes its time damping the phugoid. In a dive it almost reached Vne before heading back up.
Despite its super-slippery design, Pipistrel have not given it speed brakes. So it takes careful speed management and planning to get slowed to the relatively low 106-knot gear extension limit. (The Mooney Ovation is 140 knots.) Max flap speed is also a low 106 knots.
Seventy-five knots is the recommended across the fence Vref speed The trailing-link main gear smooths out bad landings. Although the Panthera was never designed to be a STOL plane, a proficient pilot should easily manage a 2500-foot runway at light weights.
Conclusion
If you want responsive handling, efficiency and head turning styling, the Panthera is for you.
It carries a little more than a Mooney, but less than a Cirrus, and it’s faster than both, including the SR22T at lower altitudes. It’s more efficient than both, but at the expense of a less spacious cabin than the Cirrus.
The Panthera promised a 200-knot plane that would be more efficient than anything else – and greener too, since it would eventually be offered in both pure electric and hybrid-electric versions. What it has, at least for now, is a not-quite-200-knot top speed plane with better efficiency than modern Mooneys, an adequate, albeit not capacious cabin, and sporty, well-harmonised handling.
For more information Contact: Sizwe Buthelezi – Director – Sales and Marketing on email: sizwe.buthelezi@absolute.co.za or call + 27 063 779 9545