Tour in Tomark Aero factory: how two-seater planes are born (Video)

Tour in Tomark Aero factory: how two-seater planes are born (Video)

Travelling is different when you are an aviation enthusiast. While some are looking for the best places to eat, researching nightlife, trying to list all the must-see places, I am browsing the internet for something else. I like travelling through new airports, I enjoy visiting local aviation museums and I always hope I will get to sit in an aircraft I have never flown in before. However, my latest trip to Slovakia beat all of that, because I got the opportunity to visit an actual plane factory – a place where Skyper GT9 and Viper SD-4 ultralights and EASA certified Viper SD-4 RTC are born.

Visiting industrial sites is not for everyone and I fully understand people who don’t see any value in it. However, I, for once, had never been to any plane factory before, so I was very excited about this opportunity. I wanted to see how a mass-produced ultralight plane is made, what processes does it go through, how are they controlled, what drives the design decisions. So I was really glad I got to visit Tomark Aero – Prešov, a Slovakia based airplane factory.

Tomark Aero is actually part of a bigger company, called TOMARK. Its main business is metal working: manufacturing trailer subassemblies, pressure vessels and a number of other metal components for the heavy industry and agriculture. The CEO of TOMARK has been an aviation enthusiast for years, so one day he decided to form a team that would create the perfect plane for him. Long story short, the design was so good that soon the decision was made –Tomark Aero had to make airplanes for sale.

Tomark Aero factory is located in Prešov, Slovakia.

Viper SD4, the company’s first plane, took off for its maiden flight in 2006. It is a low-wing two-seater – a quite athletic design from where I’m looking. The second plane, the high-wing Skyper GT9 took off for the first time in 2014. It is a faster, more touristic type of a plane, but more about the differences between the two models later.

Viper – is a low-wing two-seater – you can easilly recognize it by its wingtips.

Tour of the Tomark Aero factory

I had never been to a plane factory before so I didn’t really know what to expect. Somehow in my head I pictured almost a laboratory setting with people rushing to complete their tasks in time and partially assembled airplanes moving along on a conveyer. Obviously, that couldn’t be further from the truth as we found out getting a personal tour guided by Tomak Aero airworthiness specialist Robert Benetin.

Skyper is a high-wing model. It is not just the placement of wings, it is an entirely different airplane.

I wanted to see the entire process of the airplane build so the tour started in the point where both TOMARK businesses meet. Sheet metal (mostly aluminium and stainless steel) is cut into shapes using an industrial laser cutter – the exact same machine is used to cut out parts for the trailer subassemblies. The laser cuts out all the holes, so that workers in the assembly line would not have to drill or cut anything. That is pretty much the only area where these two industries meet in the entire site. Interestingly, Tomark Aero always stocks up on parts, so that the manufacturing process would not be hindered by shortages.

Entering into the factory you see an unfinished Viper.

Then these flat parts are deburred and bent into shapes using other machines. Later they form all the needed components for the structure of the plane, including beams for the monocoque construction of the front part of the fuselage of the Viper SD4. The Skyper GT9 is a little bit different, since its front fuselage is actually constructed from thin steel tubes – a common architecture for this kind of plane.

This is where the engine is fitted. You can see the bare metal construction of the Viper.

Of course, before any of these parts get put together to form the basic structure of the plane, they are coated against corrosion and marked so that the assembly line workers would know which part goes where and what process it has to go through. Both Tomark Aero models are basically fully metal, so there are a lot of different parts. I was surprised to see how controlled the process is and to find out that quality check-ups are done at each and every stage.

You can simply feel these people love aviation.

When the basic structure is assembled, the engine is installed on a special frame at the nose of the plane and workers start putting the wiring in. That is a very meticulous task, because not only engine controls have to be installed, but also cables for avionics, whole-plane parachute for emergency landing, fuel tanks switch and many other devices. After that, the outside layer of aluminium is riveted on and the basic shape of the plane is complete.

In the main assembly room the wings of Tomark Airplanes are finished and stored before installation.

At the same time, the wings are being made – also fully metal. Skyper GT9 has slightly thinner wings, but both airplanes have fuel tanks with pretty much the same capacity. Interestingly, Viper SD4 has nice wingtip devices, with a gentle curve going up and back. They are made from composite materials and serve to reduce aerodynamic drag, but, at least for my eyes, they make the entire plane look much more elegant.

Some clips from our visit

When the plane is partially assembled it is time to put it into the paintshop. Tomark Aero has the biggest closed paint booth in Central Europe. Clients can choose from a selection of paint schemes, but, if they think nothing in the catalogue represents their taste, they can opt for a custom paintjob.

Viper with its canopy and engine cover in place.

Then the airplane is taken to a nearby airfield for final assembly and flight testing. At first, the plane is finished – all devices are installed, seats, cabin upholstery are put in and temporary number for testing is pasted onto the fuselage. Initial testing is done on the ground – quality control experts look over the entire airplane checking for defects. Then all controls and avionics devices are inspected and after that the plane is prepared for its maiden flight.

Preparation for the paintjob – planes are painted in-house and customers are allowed to choose whatever paint schemes they like.

This job belongs to a test pilot. He follows instructions about what manoeuvres he has to do in the first flight and registers all the defects if there are any. Then they are immediately corrected so that the customer would get his/her plane in perfect condition.

Tomark Aero planes have an emergency landing system – a parachute that shoots out of the plane in case of a technical problem or other potentially catastrofic issue.

Finally, when the customer decides to ship his/her airplane to aforeign country, the wings are taken off, the plane is packed into a crate and shipped to its owner. It is also possible to fly-over finished airplanes directly to the customers and there is also the option to pick-up the airplane at Tomark Aero test airfield. It typically takes around four months from order until delivery, but, in some cases, Tomark Aero can deliver an airplane quicker – stocking on parts allows for some flexibility in manufacturing time. Delivery time also depends on the customer paint-job scheme, whether it is one already available or if it is customized.

Skyper’s cabin is constructed from tubes.

Both Skyper GT9 and Viper SD4 look mighty impressive for an outsider like me, but how do you chose which one to buy?

Tail structure of the Skyper.

Skyper GT9 and Viper SD4

Skyper GT9 is a high-wing airplane, designed mostly for touristic-type of flying. Because its wings are mounted on the top of the fuselage, the ingress is simple, the luggage compartment is easily accessible from the outside and the plane sports an impressive performance. Meanwhile, the Viper SD4, although a bit slower, is a more robust airplane, which will appeal to more passionate pilots. It is more athletic looking and it is EASA certified to be used in pilot schools – that is a big part of its appeal.


Differences of variants of individual Tomark Aero Airplanes

  „Viper SD-4 RTC“ „Viper SD-4 LSA“ „Viper SD4 UL“ „Skyper GT9 UL“
Wing span 8,4 m 8,4 m 8,4 m 9 m
Length 6,4 m 6,4 m 6,4 m 6,3 m
Height 2,2 m 2,2 m 2,2 m 2,1 m
Engine Rotax 912 S / ULS (100 HP) Rotax 912 UL/A/F (80 HP)

Rotax 912 S / ULS (100 HP)

Rotax 914 UL / F (115 HP)

Rotax 912 UL/A/F

(80 HP)

Rotax 912 S / ULS

(100 HP)

Rotax 912 UL

(80 HP)

Rotax 912 ULS

(100 HP)

Maximum take-off weight 600 kg 600 kg 472,5 kg
Cruise speed 195 km/h 195 km/h 195 km/h 220 km/h
Maximum speed 240 km/h 240 km/h 240 km/h 250 km/h
Ceiling 4 725 m 5000 m
Runway (take off/landing) 240/ 176 240/ 176 150/140 m 120/80 m
Fuel tank capacity 100 l 70 / 100 l 70 / 100 l 88 l

In LSA specifications both planes are heavier (maximum weight reaches 600 kg), which means that a bit-longer runway is required. Also, instead of the 70l fuel tank LSA specified the Skyper GT9 and Viper SD4 get 100-litre fuel tanks.

In short, Skyper GT9 is easier to use and maintain and to live with. It is also faster than Viper SD4, although a little less rigid. Meanwhile, Viper SD4 is a sportier airplane. It is strong, reliable and looks good. It is also very easy to fly – a perfect choice for pilot schools. Viper SD4 can be also used as a great towing machine for gliders or banners. Ideal for flight clubs.

Wingtips of the Viper look very elegant, but are also functional – they reduce aerodynamic drag.

By the way, I asked about the safety record of these planes. This really not-polite question was met with a smile – while there have been several crashes, none of them were caused by mechanical faults nor factory defects.

Summing up

It is the first airplane factory I’ve ever been to. While I was expecting a busy and almost laboratory-like setting, it was much simpler – just an industrial site where everyone fulfils their functions. There are no robots as far as I could see and every plane was caressed by human hands on every step of the way. Kind of a romantic image, to be honest, but it is very technical.

Assembly is completed in a nearby airfield where flight testing is done as well.

Everything regarding the airplane manufacturing is done to the highest possible standards. The quality control is meticulous and watches over every airplane at every stage. However, make no mistake – Tomark Aero airplanes do have some passion about them. They appeared in this world because the CEO of the company simply loves aviation and this sense is visible throughout the factory. I saw posters with fighter jets in one of the stations where the cabin and interior get installed – these people just love what they are doing. And I loved visiting the factory, learning a lot about manufacturing of ultralight airplanes and seeing these birds before the wind touches their wings.

Huge THANKS to Tomark Aero for allowing us to visit their factory. Definately visit their website –

The fastest propeller-driven airplane was developed during the Second World War?

The fastest propeller-driven airplane was developed during the Second World War?

Science and technology is constantly moving forward, but that doesn’t mean that some records will just continue to be broken. While planes with piston engines are still being developed, many roles nowadays are being fulfilled by jets. Therefore, it doesn’t really come as a surprise that the fastest propeller-driven airplane was actually born during the Second World War. However, we’re not really sure which one would it be.

You may think that describing such record is simple – whichever one was the fastest is the record holder. But there are some layers to this question that we’d like to explore. But, first things first, the official record holder is Grumman F8F Bearcat – American single-engine carrier-based fighter aircraft.

Rare Bear, heavilly modified Grumman F8F Bearcat, is the fastest piston-engined airplane in the world. (Don Sleeter, Wikimedia)

It took off for its maiden flight in August 1944 and was a mighty impressive aircraft. It was so potent, so quick and so versatile it managed to stay in service up until 1963, but even then it never stopped flying. AT this point enthusiasts wanted to get their hands on one and many did.  Grumman F8F Bearcat became popular between acrobatic flying pilots and air racers. Of course, for these purposes plane had to be heavily modified. That was how the fastest of them all – the Rare Bear – was born.

Rare Bear, extremely modified F8F Bearcat, dominated Reno Air Races for decades. It was just too fast for others to even think of competing with it. Its official record is 850.24 km/h and so it is the fastest airplane with piston engine in the world. Or is it?

Hawker Sea Fury was fast in service already, but people have modified these planes for air racing. (Don Ramey Logan, Wikimedia(CC BY-SA 4.0)

Rare Bear holds the official record, but another heavily modified airplane, based on British Hawker Sea Fury. This fighter plane was also born at the end of the Second World War. Seeing that war is pretty much over, RAF lost interest in Hawker Fury, but the Royal Navy still wanted the fighter, so a Sea Fury version was developed. It was amazingly quick for its time, but, when got even quicker after it finished its service and got into hands of acrobatic pilots and air racers. Unofficial record of highest speed of propeller-driven airplane belongs to a heavily modified Hawker Sea Fury – 880 km/h.

So we know which airplane holds the record. But both of the contenders were heavily modified and it is kind of interesting to see, which airplane was the fastest straight from the factory. That would be German Dornier Do 335 Pfeil. It was introduced at very late stages of WW2 and didn’t manage to prove its full potential. However, we do know it was the fastest propeller-driven airplane in the entire war.

Blue Angels, United States Navy’s flight demonstration squadron, transitioned to the Grumman F8F-1 Bearcat in 1946. (USN, Wikimedia)

Dornier Do 335 Pfeil had two engines mounted in the fuselage and each one of them drove a separate propeller – one was pushing the airplane, while the other one was pulling. This peculiar arrangement meant that Do 335 Pfeil could reach speeds of up to 765 km/h and even if one of the engines was turned off or disabled it could still fly at 563 km/h. Only 11 fighter planes were delivered in 1945 until Americans took over the factory, but those Allied pilots who witnessed the Do 335 Pfeil could not believe its speed at level flight.

Dornier Do 335 Pfeil had to engines and two propellers – one was mounted on the tail of the airplane. (Guinnog, Wikimedia(CC BY-SA 3.0)

Now the only surviving example is in a museum, so we will never know what speed could it reach in a dive. However, we do know that a British Supermarine Spitfire reached 1,110 km/h speed in a dive in 1952. That’s the closest propeller-driven airplane ever got to the speed of sound. That is an impressive performance, but it is far from the actual fastest plane in the world.

A similar Supermarine Spitfire got close to the speed of sound several times, but only in a dive. (RAF official photographer , Wikimedia(CC BY-SA 3.0)

That would be Lockheed SR-71 Blackbird, which in 1976 reached 3,530 km/h. This strategic reconnaissance aircraft is retired from 1988, but is still regarded as one of the best airplane designs ever.

Bell P-39 Airacobra fighter plane recovered from the bottom of the lake in Russia (Video)

Bell P-39 Airacobra fighter plane recovered from the bottom of the lake in Russia (Video)

It‘s been more than 70 years since the Second World War ended. However, traces of the biggest humanity‘s conflict can still be discovered. Just recently a Bell P-39 Airacobra fighter has been retrieved from the Lake Shukozero in Russia and a year ago a couple of Sherman tanks have been recovered from the bottom of the sea almost in the same place.

Bell P-39 Airacobra was mid-engined and therefore required a long shaft to spin its propeller. (US government, Wikimedia)

Bell P-39 Airacobra is a peculiar airplane. It took off for its amiden flight back in 1938 and entered service in 1941. It featured one unusual construction solution – its engine was mounted behind the pilot, which meant that a long shaft was required to spin a traction propeller. However, it was a good fighter plane – it is often said that together with P-63 Kingcobra, the P-39 was one of the most successful fixed-wing aircraft manufactured by Bell. But it did have one issue – its engine was not turbocharged or supercharged.

It is likely that the plane will go to the museum as is – it is just more authentic that way. (Минобороны России)

It meant that it could not operate at high altitude very well and therefore RAF did not want it. Meanwhile soviets took it gladly – 4,746 P-39s Airacobras were sent to Soviet Union to aid its efforts of fighting Nazi Germany. However, this one did not fall into a lake because of some intensive fighting – this accident occurred on a training mission.

As it was said, Fyodor Varavik lost control of his airplane and crashed into Shukozero Lake in northern Russia. Since it was March of 1945, lake was covered with ice so it could’ve been that Varavik performed emergency landing, but at the result is clear – P-39 Airacobra sunk to the depth of 45 metres. Recently this plane has been discovered and Russian Navy personnel assigned to the Northern Fleet organized the recovery operation.

Divers reached the plane, but no human remains were found – only a boot of the pilot was inside of the plane, together with 37 mm ammunition and oxygen tanks. Bell P-39 Airacobra was retrieved and now will find its way in a museum. Very likely, it will not be restored – it will remain authentic with its own story.

Plane was found in a lake in Murmansk region. Not too far away last year Russian Navy recovered a couple of American Sherman tanks. They went down with the SS Thomas Donaldson ship, when it was torpedoed by a German U-Boat.  Tanks were also meant to help Soviet Union – in total 4,102 M4 Sherman medium tanks were sent to the Eastern Front. Interestingly, despite spending 71 years in salty water, tanks were in decently good condition. Some say it is because they were packed very good and could resist water damage for some time.

People love stories about tanks and planes sunken to the bottom of the sea and later discovered by some enthusiasts. But the truth is that most of it is just some legends and myths that are completely made up or got distorted through the years of going from one person to another. However, it is very satisfying to see these gracious machines emerge from their watery grave, because some more years and nature will claim what is hers. Soon all of the lost WW2 weapons will simply be rotten away.

The largest NASA’s cargo airplane still uses turboprop engines and can trace its ancestry to WW2 (Video)

The largest NASA’s cargo airplane still uses turboprop engines and can trace its ancestry to WW2 (Video)

Planes age differently than most other things. While a 10 year old car is really not in its prime anymore, an airplane at that age is still considered pretty young. And technology is not progressing that fast – our beloved Boeing 737 took off for the first time in 1967 and it is still going strong. But, even in this context, the largest NASA’s cargo plane seems a bit old – it can trace its roots to a legendary WW2 bomber.

Pregnant Guppy was a little shorter than Super Guppy. (NASA/DFRC, Wikimedia)

NASA definitely needs a good cargo plane. Not only rocket modules are big in diameter, but also laboratory equipment has to be carried from one place to another, sometimes in one piece. That is why Aero Spacelines made a Pregnant Guppy, which took off for the first time in 1962. It was a ballooned Boeing 377 Stratocruiser and looked pretty much like a whale.

Super Guppy looks a lot like a whale. (NASA/Tony Landis, Wikimedia)

While the Pregnant Guppy was very useful in the initial stages of the Apollo program, it soon became clear that an airplane that was a bit longer would be preferred. And so it was built using the Boeing C-97 Stratofreighter and the Boeing 377 Stratocruiser as a basis. Interestingly enough, the C-97 was actually a derivative of the famous B-29 Superfortress bomber, which was the one dropping the atomic bombs in Japan during WW2.

Only the top portion of the C-97 Stratofreighter was ballooned – the cargo compartment floor remained the same. (NASA, Wikimedia)

The Super Guppy took off for the first time in August 1965. It was exceptionally large, although it resembled the Pregnant Guppy a lot. It had a distinctive balloon-shape cross section, because only the upper part of the fuselage was enlarged. The Super Guppy was easily large enough to fit separate parts of rockets as well as large modules from the Apollo and subsequent programs. It was so useful that soon it was decided that some other C-97 bombers could be transformed and one Pregnant Guppy was used up as well. In total, 5 Super Guppy airplanes were built.

Only one out of five Super Guppies is flying. (NASA/Tony Landis , Wikimedia)

You probably have seen the Airbus Beluga and Boeing Dreamlifter cargo airships. They are somewhat similar to the Pregnant Guppy and Super Guppy and it is not a coincidence. At some point, Airbus bought the rights to the Super Guppy and used a couple of these airplanes for its own logistic operations. And Boeing was also interested – after all, it was Boeing’s aircrafts that were used to create the guppies.

Super Guppy had no problem swallowing ridiculously large loads like this Saturn V S-IVB stage mockup. (Saturn V S-IVB stage)

Nowadays, only one Super Guppy is still flying and it belongs to NASA. It was originally registered somewhere around 1983, but it is still a very old design. C-97 Stratofreighter is out of production since 1958. Super Guppy is powered by four turboprop engines. It is actually quite unusual to see a plane with propellers carrying the latest NASA inventions today, but it is dependable, so why would they retire it?

The wingspan of the Super Guppy is 47.6 metres, length – almost 44 metres. It is not its size, however, that is so impressive, but its capacity – it can carry 24.7 tons of weight. Despite being quite old, it is probably going to remain in service for the foreseeable future because it is just that useful. Who knows, maybe it will still be flying when humanity will decide to lay its foot on Mars.

This is how US military helicopters might look in the future (Video)

This is how US military helicopters might look in the future (Video)

Military helicopters are a fascinating piece of equipment. There are actually some hardcore fans of some American helicopters, specifically – AH-64 Apache. However, many American military helicopters are starting to feel their age and will need replacement soon. It is likely that a new generation of military helicopters will look something like this.

There is a program, called Future Vertical Lift, aiming to find a reliable helicopter base, which would underlay all five main helicopters that US Army needs. Of course, since the roles are different, they will not look the same, but are supposed to share sensors, avionics, engines, countermeasures and some other components. Also, these helicopters must be quick and capable of carrying heavy loads. We recon, Sikorsky S-97 Raider gives a good indication of what these aircrafts will look like.

S-97 Raider in the middle of test flight.

Just by looking at the picture you know it is not an ordinary helicopter. First of all, it does not have a normal tail rotor. Instead of it there is a pushing propeller, similar to those found in gyroplanes. It is meant to make the helicopter faster.

The problem with helicopters is that they are slow. Usually there is nothing pushing the aircraft forwards, meaning that no propellers are vertical and perpendicular to the helicopter’s fuselage. This is solved by compound helicopters that have propellers pulling or pushing the aircraft forwards. In fact, the fastest helicopter ever was a compound one – Eurocopter X3 prototype, reaching the speeds of 255 knots (472 km/h). It had two propellers at each side and was working pretty well, but did not pass prototype phase. It is said that Airbus Helicopters is still working on the idea and may present a new aircraft soon.

Some would argue that S-97 Raider just looks weird.

Sikorsky S-97 Raider has two coaxial rotors, spinning at different directions. It increases payload and eliminates the need for the tail rotor. It also features a fly-by-wire controls and antivibration system. All in all, S-97 Raider is extremely manoeuvrable at low speeds – flying slowly it is controlled by tilting rotor separately from each other or in one unit.

At higher speeds Raider uses rudders – similarly to a plane. It can reach speeds of up to 240 kn (444 km/h), but in the future, with more powerful engines maximum speed will increase. We will remind that Apache can reach only about 158 kn (293 km/h). Six soldiers and a couple of pilots will fit in Raider, but it can help evacuating injured soldier or carrying some cargo. It can also be used as an attack helicopter, armed with .50 caliber machine gun and rocket launchers.

Sikorsky and Boeing are working on another aircraft for the Future Vertical Lift program – it looks similar, but is a bit bigger and is still not flying – SB-1 Defiant. The biggest competition to Sikorsky’s idea of what future military helicopter should look like is Bell V-280 Valor – a helicopter with two large horizontal rotors side by side. We will probably write about it when it makes its maiden flight – it might happen this year.

Future Vertical Lift is trying to replace H-60 Black Hawk, AH-64 Apache, CH-47 Chinook and OH-58 Kiowa with a unified system. So far, it looks like Sikorsky’s technology is taking bigger leaps than competitors. Therefore, it is very likely that future helicopters of US military will look something like S-97 Raider.

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