When The Sky Is The Limit: Light Sports Aircraft Pipistrel Virus 912 SW Review

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While on business trip to Slovenia, I decided to take an opportunity to visit  "Pipistrel" factory which produces sailplanes, ultralight airplanes and motorized hang gliders. I drove to Ajdovscina from beautiful town of Portorož, which is located on the Adriatic coast, by car. A trip through the Alps submerged in clouds, as indeed the whole of Slovenia, left a lot of good impressions. In Ajdovscina, as was previously agreed, I was greeted by a factory representative Tadej Hozic and ... the clouds ceiling as low as the tree-tops.

In 2008, NASA handed out 250 thousand. USD for companies that are developing small airplanes intended for mass production. Four teams presented double seated airplanes and competed in categories such as the rapid rise, speed, economy, controllability and noise. The winner of 100 thousand dollar worth prize became creators of an ultralight airplane Virus 912 SW, company „Pipistrel“ from Slovenia.

Company "Pipistrel“ was founded in 1982 by four think-alikes: Gliders Janko Bezjak and Marjan Bozic together with Ivo Boscarol and Bojan Sajovic who had experience in manufacturing radio-controlled models

Modern Enterprise

The first part of my visit was to the plant. It is equipped with the latest technologies, many manufacturing processes are robotized. An integrated management system covers all the parts of the manufacturing process – from aircraft design to test flights and preparation of the aisplanes for the maiden trips to new owners‘ home airfields.

What I found very impressive is that electricity used in the plant is produced exclusively by solar cells. Solar cells cover not only the roof but also the barriers of the balconies. Currently, „Pipistrel‘s“ solar power plant is the largest not only in Slovenia, but also in the entire Balkan peninsula. Tadej has revealed that most of the electricity produced by "Pipistrel“ is being sold to local electricity grids. Due to alternative energy sources and energy efficient technologies utilized in the manufacturing process, „Pipistrel“ claims 100% energy self-sufficiency. The factory premises are heated and cooled by geothermal system. "Ecolution" (Ecology + Evolution) philosophy emanates from everywhere - from alternative energy solutions to staff‘s cars, many of which are hybrid. Aircraft the company produces are friendly to the environment as well.

Low wing aircraft is in the pipeline

Currently, the factory builds seven aircraft per month. "Pipistrel is currently producing motorized hang gliders Spider and Twister, motorized two seat gliders Sinus and Taurus, single seated Apis sailplane and ultralight airplanes Virus and Virus SW. The factory representative revealed that the company is developing low wing four seater which will be using Lycoming IO-360 engine.

I was shown the design section, the composites workshop, small parts assembly plant, metal work shop, engine testing and electrical installation departments and aircraft assembly line. In the meantime the sky cleared up and I was informed that the plane I originally came to see – Virus SW is ready for a test flight. In fact, I was very curious to experience how the new virus SW is different from its predecessor, with 12.5 m wingspan.

Smaller And More Robust

The new version of the Virus has almost two meters shorter wingspan -  down to 10.7 m. SW stands for „Short Wing“. Even though shorter wingspan is the most obvious change there are more less evident ones: the shape of front wheel spat was changed to become more aerodinamically efficient, the stabilizer, rudder and elevator dcreased in size yet were made to be more sturdy. This is not surprising, given that the never exceed speed of SW was raised to 303 km / hr. I was also informed that the construction of fuselage was new from ground up. It was greatly strengthened in order to withstand the increased flight speeds.

Now Virus SW cruises at speeds exceeding VNE of the old Virus 912, The selection of engines is between 80 or 100 HP 912 Series Rotax. Currenly factory does not offer SW with the turbocharged 115 HP Rotax 914, but given the performance figures of the 100 HP version this would probably would be overkill anyway. The entry-level engine is coupled to Pipistrel‘s proprietary in-flight variable pitch propeller, which also can be feathered. The more powerful engine  with variable pitch Woodcomp airscrew. All family of Virus aircraft can be equipped with ballistic rescue system GRS. It certainly takes a hold of the lugagge space, but the added safety factor is probably a good trade-off.  The main advantages of GRS comparing it to other manufacturers‘ products  is the fact that the parachute can be opened at any speeds - even those exceeding VNE and also close to the terrain.

Test aircraft was equipped with the 80 HP engine and ticycle landing gear (the basic aircraft comes in taildragger version).

Spectacular takeoff

Together with Pipistrel‘s test pilot we entered the cockpit. Like in the earlier Virus 912 the interior feels somehow cramped. My guide to confessed that I was not the first to mention the lack of space and the less than average seats. Starting the engine, as it is with any Rotax was non issue. Even though it was the first start of the day, the power plant fired immediately and idled very gently and quietly.  We taxied to the holding point of runway 27, checked out the readings - temperature, ignition systems and lined up. The flaps were set to the second position – 19 degrees. Propeller pitch set to fine, full throttle and very, very soon we were already in the air. The whole takeoff roll off was less than 80 meters. At 74 km / hr. The flaps are raised to the 1st position (9 degrees), and at 90 km / hr to zero. Climbing at 110 km / hr. speed produces about 6 m/s. Mighty impressive, as the power plant is only 80 hp, while the take-off weight was close to the allowable maximum (472,5 Kg in Europe, although it is certified to 600 Kg MTOW).

The Range Is Not An Issue

At the height of 300 m were subjected to breathtaking alpine views. The sky was still a little bit cloudy, but the visibility was perfect. However, we had no time to admire the scenery. Aircraft „conduct“ tests were to about to begin. I was expecting that the SW will behave similarly to its older, sailplane-resembling sibling. Boy, I was wrong. While flying at 130 km/h the aircraft has perfect harmony of the controls – ailerons the lightest, rudder the heaviest - the airplane is exceptionally obedient and well-behaved. When you reach 150 km / hr turns do no longer require rudder inputs. The plane is extremely obedient and stable in a turn. As far as I could tell there was not even a hint of slipping without any footwork. Engine test comes next. At 5000 rpm I begin to increase the pitch of the airscrew until the engine speed droppes to 4600 rpm and manifold pressure reaches 27 In/hg – this is 75% load, as per Rotax datasheets. Airspeed jumps up to 240 km / hr, while there is only 80 HP under the bonnet! Even more impressive is the fact that the Brauniger Alpha MFD multifunctional display indicates that the fuel consumption is only 12.5 liters per hour. I make a quick calculation that with the standard 100-liter tanks the SW has endurance of more than seven hours. At this speed it means the range of  1,700 km. This aircraft is as close to Ultimate Touring Machine as it can get, the only drawback being the inferior seats and seating position which can seriously impair ones ability to withstand 7-hour trip (that‘s providing your bladder will not ask you for a stop sooner than that). I noticed that even at such a speed plane flies very quietly and vibrations are kept at minimum. Out of curiosity, I took off the headphones – it is possible, albeit raising your voice quite significantly, to communicate without them. As we all know acoustic comfort is a very important factor in extended trips.

Unexpected Sensations

We continued with stall tests. Lowering flaps to "2" and reducing the speed to 50 km / hr did not provoke the stall and was still controllable around all three axis. The only indicator of how close to the stall we were was the ASI, lagging somewhere near the bottom of its scale and Brauniger‘s stall warning emitting alarming sounds. SW was persistently reluctant to lower the nose and/or drop a wing. By further increasing the angle of attack you will force the aircraft into mushing at 2 to 2.5 m / s vertical speed. Bearing in mind that with a 100 hp engine, this airplane flies 270 kilometers per hour its speed envelope is incredible!

However, one of the most impressive demonstration was that of the air-brakes. Having reached 500 m the engine speed is reduced to a minimum, nose is lowered and air brakes are opened. The feeling was as if you are speeding down the Lillehammer Olympic Complex ski jump slope. Airplane nose points 75-degree angle to the ground, the aircraft remained completely stable and stabilized at the speed of 220 km / hr. IAS. Within several seconds we lost about 250 meters. It's more like a roller-coaster not an airplane.

Weaknesses Remain In The Shadow

Before landing we made a low pass. We flashed at 260 km/h a few feet above the active runway.  Then - a sharp rise over the factory buildings, 80-degree right turn and – in barely few seconds we are turning to final.

The landing strip is getting close fast. Speed - 100 km / hr, flap position - "2." Descent is accelerated by the air brakes - the VSI indicates 5 m / s. The approach angle is impressive. Landing speed - 50 km / hr, the wheels touch the ground and after merely 60 to 70 meters ground roll we are vacating the runway.

I must admit I was stunned by this aircraft. It is extremely stable, all controls are excellently belanced throughout the entire range of flight speeds, the stall behavior is nothing short of amazing. Noise in the cockpit is delightfully low, and even more impressive is the frugal fuel consumption. Two things on this plane could be better - seats and luggage space (or rather lack of it), especially when GRS system is installed. But those drawbacks are redeemed by otherwise excellent combination of speed, stability, build quality and quietness.

As soon as I got out of  the plane I was greeted by Pipistrel‘s CEO Ivo Boscarol'is. He shook my hand and handed the gift that will remind me the visit to the factory. The expression on my face and my shining eyes have probably told him more than any words I could have found at that moment.

Technical Data

 
Virus 912
Virus 912 SW 80
Virus 912 SW 100
Length
6,5 m
6,5 m
6,5 m
Wingspan
12,64 m
10,71 m
10,71 m
Height
1,85 m
1,85 m
1,85 m
Wing area
11 m²
9,51 m²
9,51 m²
Drag to lift ratio
24, at 110 km/h
17, at 118 km/h.
15, at 118 km/h
Empty weight
284 kg
287 kg
289 kg
MTOW
472,5 kg (European Ultralight Registration); 600 kg (LSA registration)
472,5 kg (European Ultralight Registration); 600 kg (LSA registration)
472,5 kg (European Ultralight Registration); 600 kg (LSA registration)
Cruising speed at 75% power
225 km/h.
246 km/h.
273 km/h
Maximum level flight speed
240 km/h.
264 km/h
283 km/h
VNE
250 km/h.
303 km/h
303 km/h
Service ceiling (450 kg)
8100 m
6200 m
6800 m
Range
1280 km
1650 km
1450 km
Engine
ROTAX 912 UL
ROTAX 912 UL
ROTAX 912 ULS

Tine Tomažič speaks about Virus SW at AERO Friedrichshafen 2009

NASA/CAFE Test pilot reviews the Virus:

A very detailed demonstration of Virus at Sebring 2011 Expo, by Dan Johnson.

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Comments 6 comments

Spirit Whisperer profile image

Spirit Whisperer 5 years ago from Isle of Man

An excellent article about very exciting technology. Have you also heard about Steorn. I have written an article about it which you might be interested in. http://hubpages.com/technology/Free-Energy-by-Steo

It is a pleasure reading your hubs. Thank you.


Green Wasabi profile image

Green Wasabi 5 years ago Author

@ Spirit Whisperer thanks so much for your comment!


VictorSierraMike profile image

VictorSierraMike 5 years ago

Great review of a fantastic aircraft.

In fact Pipistrel is now offering an electric 2 seat sailplane "Taurus". The Li polymer batteries on the aircraft have enough capacity to power it to altitude of 2000 meters, which is perfect for soaring. Alongside that they also have developed a trailer which is covered by solar cells. On a sunny day the trailer is capable recharging Taurus' batteries in 5-6 hours. They call it flying for free. I call it a visionary, innovative, and extraordinary company.

You can find more info about the Taurus electric here:

http://www.pipistrel.si/plane/taurus-electro/overv...


Jonathan Edan Charnes 4 years ago

The plane would be safer with a higher wing loading. If it stalls at 50 mph, and you are cruising at 150 mph, you can unexpectedly put 9 g's on the air-frame if you hit clear air turbulence! Better have the ballistic chute. With a wing that stalls at 70 mph, you would only put a little over 4 g's on the air frame if you hit clear air turbulence at 150 mph. It would be nice if the plane were certificated or instrument flying


Lima Sierra 2 years ago

I think Pipistrel designers thought about this issue. The flaperons on this aircraft are set to -5 degrees for cruise, which significantly increases the stall speed and, subsequently, wing loading. And yes, it can be equipped with the ballistic chute. In my 0pinion it is one of the safest light aircraft ever built. Sort of tight inside, bad body weight distribution due to very low seats and visibility in the circuit is poor, but still a great design in terms of safety and efficiency.


Penelope Cruz profile image

Penelope Cruz 13 months ago from Washington, DC

Wonderful review. Very informative, this was chocked full of interesting facts.

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