In an interview for the Aerospace magazine, Grob’s Test and Chief Instructor pilot Major Ret. Tom Reinert talks about the company’s history and its breakthrough trainer Grob 120TP.
The story of GROB AIRCRAFT SE (previously known as Grob Aerospace) started in Tussenhausen-Mattsies in South Germany in 1971. Since then, Grob has become an important player in the world’s aircraft manufacturer market which can design, test and certify a range of complete carbon fiber 21st century trainers to meet the needs of today’s air forces worldwide. Grob Aircraft has its own production plant on site along with its own airfield and testing facilities.
Interviewed by: Kateřina Ševčíková Urbanová
Grob Aircraft started as Grob Aerospace in 1971, can you tell us more about the company’s history?
The history starts really with the person behind it. The founder was Dr. Burkhard Grob, a Bavarian mechanical engineer who ran a machine tooling company in Mindelheim. He had a passion for aviation and was a glider pilot. When he wanted to buy a glider airplane for himself and was told by an aircraft manufacturer that he would need to wait for two years to get his new glider he cancelled the order and said that he would build a new one from scratch faster than that. Unfortunately, I have never met him but that describes his personality pretty well. He passed away about 2 years ago at the age of 90.
In 1971, Burkhart Grob Luft- und Raumfahrt GmbH & Co. KG (that was the former name) began to build the “Schempp-Hirt Standard Cirrus“ under a license at the machine tooling company headquarters in Mindelheim. More than 200 aircraft were built back then. The founder’s vision was to deliver a full composite glider at a very competitive price with a high rate of production. The G102 ASTIR CS was born from that. A full composite glider with a price tag of about 20,000 Deutsche Mark introduced in 1976 was a disruptor in the glider world. That led to a relocation to a newly established airfield in Mindelheim-Mattsies just a couple of kilometers away from the main location. Many more glider types followed including the first motorized glider in the early 1980s. The motorized glider led to the development of an own Grob 2500 engine with 90hp. That was used in the G109B. A real single engine piston aircraft followed with the G115. Dr. Grob was a pioneer and he always looked for new ideas and designs. In 1987 the GF200, 4 to 6 seat aeroplane in a pusher configuration was envisioned. 4 years later, the GF200 performed its maiden flight. Two more prototypes never made it to production. The G140TP and the G160 Ranger. The G140 TP was a 4 seat fully aerobatic aircraft powered by the same Rolls Royce turbine as the G120TP. So you can get the whole family airsick in one flight. The other one, the G160 Ranger was designed to be a business aircraft. Powered by a Pratt & Whitney PT6 it is pretty similar to the Pilatus PC12 regarding envelope and performance.
The special mission aircraft were also made in this period but I will mention them later in more detail.
2005 was the year of the maiden flight of the Grob 180 SPn jet, the world’s first fully carbon reinforced business jet.
That was the time when Dr. Grob retired and sold the company to Execujet in Switzerland. The company operated under a new name, Grob Aerospace, until it went bankrupt in 2008. The bankruptcy was rather the result of the overall global financial crisis than bad business on the Grob side but that’s life.
The advantage of that is that we wouldn’t have the current company if that wouldn’t have happened, and there would not be a Grob G120TP which has been the first new aircraft designed and produced by Grob Aircraft.
Grob revolutionised the making of complete carbon fiber airframes by using the “wet carbon fiber technique” and is one of the world’s largest and most experienced composite aircraft manufacturers today. What are the main benefits of this technology?
The wet lay process is an “easy“ process, as you don’t need special tools or complicated machines. But it requires hands-on experience and good craftsmanship skills. Fortunately, we do have this expertise in the company as a result of our experience of more than 48 years. In addition, for well-educated light aircraft builders, GROB has good in-house training capabilities to teach people from other professions to become experts with the composite technology. Although most of the fabrication process is done manually, the reproducibility of the composite parts and process reliability is a big advantage. For these purposes, GROB uses a resin impregnating machine that allows for the correct amount of resin within the laminate, and thus a constant fiber volume content. This machine prepares a kind of “just-in-time-prepreg“ that can be easily processed.
A two-stage cure cycle gives sufficient strength to the composite structures. In the first stage at 60°C, the part is exposed to vacuum pressure that provides an excellent compound of the laminate layers. After demolding and assembly of parts, the second stage is performed at 80°C. This provides the required strength and stiffness for the airframe at its maximum operating temperature of 72°C.
Also, in case of a necessary repair this “low temperature/low pressure-technique“ allows a field repair with very few tools. You just need to build a box around the repaired part and heat it up to that temperature again to cure the repaired material. This could be done with a hairdryer and a “shoebox“.
Grob Aerospace was bought by H3 Aerospace at the beginning of 2009 and became GROB AIRCRAFT SE. What were the key changes the company went through after the acquisition?
H3 Aerospace is owned by 3 siblings. Their family name starts with an H. That is the reason for the H3 name. Grob Aircraft is fully owned by H3 which is a family company. This means that the strategy is more focused on increased value in the future rather than the short term results a regular stock market company would be looking for.
One of the 3 siblings is actually the CEO (Mr. André Hiebeler, editor’s note) and he runs the show. His sister and brother are acting more in the background since they run their own businesses.
Since the acquisition, the new owners have mainly focused on the military aircraft market, and the glider division has been transferred to another company.
Shortly after that, in 2010, GROB AIRCRAFT SE introduced the new Grob 120TP to the market. Originally designed to be a further development of the G 120A, the G 120TP almost turned into a new type of aircraft. Can you tell us more about the development of this aircraft and the key features of the new G120TP?
The idea for the G120TP goes back to the “Enhanced Flight Training Aircraft Concept“. Meaning one aircraft that can be used for a long time and covers many missions and training tasks. Historically, military flight training was accomplished with many different aircraft types to become a rated pilot. In my case I flew 3 different aircraft types before I earned my wings as a military pilot. The reason for that was just that the first two aircraft types didn’t provide all the training content required for becoming a rated pilot. The G120TP covers at least two of the three aircraft types regarding training options and offers even more in addition to the old trainers. The big advantage is that you save time in transition training and by flying just one aircraft for a longer period of time the student pilot gains more proficiency in this aircraft and is a safer pilot. A good example for an efficient downloading is the situation we have together with Aero Vodochody’s new L-39 NG. The L-39 NG has the same Avionic System as our G120TP. It is the GENESYS Aerosystems IDU680 Electronic Flight Instrumentation System (EFIS). If a student pilot learns to fly in the G120TP with the IDU680 EFIS he or she will know already how to use that in the later training in the L-39NG. So the pilot interface to the aircraft is the same. It is just a new airframe behind that interface but the student is already proficient in the use and by that saving a lot of time not having to learn something new. Also the so called “law of primacy” that I described above is observed by that. The added value is also achieved by downloading training from (in my case a twin jet trainer) to a single engine turboprop with the same performance values to a much more cost-effective price point.
Those ideas formed the design criteria for the G120TP and on 25 May 2010 the very first G120TP, or at least the Proof of Concept (POC) of it, performed its maiden flight from our Airfield in Mattsies/Germany. The POC was based on a G115TA airframe which is almost the same as the G120A. On 1 August 2012, the very first “real“ G120TP performed its maiden flight. That was the prototype that was mainly used for the required certification flight tests. In May 2013, so just 3 years after the maiden flight, EASA CS 23 Certification was issued.
So can you describe the main differences between the G 120TP and its predecessor the G 120?
The G120A airframe is a complete carbon fiber aircraft. Carbon fiber is very strong and lightweight but sometimes even in aircraft manufacturing “less is more“. Let me explain a bit what I mean. You have already heard that Grob Aircraft has this long experience of composite aircraft manufacturing and knows about the pros and cons regarding the different composite technology. In the G120TP we went back from a full carbon airframe (G120A) to a mix of carbon fiber and glass fiber structure. So we combine the different materials to achieve the best possible result. All parts that need to be very strong are made from carbon fiber and those parts that don’t need this extra strength are built of glass. This also allows us to install antennas inside the fuselage. Should the frame be built only in carbon, this would not work due to the “shielding“ of the radio waves inside a fuselage made of carbon.
If you see a “naked“ G120 A, so no filler yet and no paint applied, it is completely black due to the carbon fiber. A naked G120TP has a lot of yellow/greenish parts and the black color is, for example, on the wing and lower fuselage where the gear and the wings connect to the fuselage.
The other main difference is the propulsion. A 6 cylinder 260 hp engine and a 3-bladed prop versus the 456 hp turbine with the 5 bladed propeller. Due to the turbine, the TP burns Jet Fuel instead of AVGAS. In some parts of the world, AVGAS is hard to get and AVGAS will vanish from the world in the future and will be replaced by lower quality fuels with no lead at all. The G120A’s ceiling is 18,000 ft and the TP’s is 25,000 ft. I have about the same amount of flight hours in both aircraft. I was never above 13,000 ft in a G120A but in the TP I cruise all the time at FL250 if I needed to go somewhere. We also changed the flight controls a little bit and the big game changer besides the performance is the cockpit. The current G120TP features a full glass cockpit with dual FMS and optional autopilot. The most modern G120A (build 2013) is not even close to the features available here. The size and weight are pretty much the same and they really look like siblings when parked next to each other on the ramp. The nose is longer on the TP and it has winglets and more surface area behind the center of gravity (CG) for controllability and stability. I personally believe and know that the G120TP is actually easier to fly for a student pilot than the G120A. Even when the numbers (bigger envelope, more power) often lead to an assumption that the opposite would be the case. This also shows the improvements that we made in developing the G120TP from the G120A (or 115TA).
And how does the G 120 TP differ from its main competitors?
The G 120 TP has very competitive economics and due to its cockpit arrangement – the side by side seating – supports high efficiency training.
The real competitors regarding the aircraft performance are the TEXTRON T-6, Pilatus PC-9 (or 7 Mk. II), and maybe the KT-1. Those are all metal aircraft and in a tandem seating arrangement powered by a Pratt & Whitney PT-6 turbine. They are about 3 times heavier and the power output is also higher but in terms of the power to weight ratio the G 120 TP is about equal or better. Since they burn about three times more fuel than the G 120 TP and have a more powerful (and more expensive) turbine the operating costs are much higher.
Another advantage of our G 120 TP is its Civil certification. The aircraft is certified in the EASA CS 23 category and also in FAA FAR23. So you can register the aircraft in a civil registry with a civil licensed pilot flying it. That also means that you can use the aircraft for training for civil licenses. You can’t do that with military- only aircraft as no Civil Aviation Authority (CAA) will allow training within an Approved Training Organization (ATO) on military registered aircraft.
Since the beginning of the serial production of G 120TP in 2013, more than 100 aircraft have been delivered to seven global fleet customers mainly for basic military pilot training. What were the key elements of this success story? What training needs does G 120TP cover?
One key element for sure is that Grob has been on the market for a while and has been providing training aircraft and dependable service for more than 4 decades. The Royal Air Force was the biggest G115 operator with 117 airplanes in different training locations. Many countries send their pilots to the UK for training. So some of the new customers, like Kenya in 2013, were attracted by other air forces’ positive experience with Grobs.
The other key element is the unique performance in a side-by-side cockpit mentioned above. If you want to do ab initio and elementary flight training there is no other comparable side-by-side trainer available. Military flight training is often categorized in phases such as I to IV or Elementary, Basic, Advanced, Fighter Lead-In & Conversion. The G120TP covers the Elementary & Basic Phase and can even take over the early parts of the advanced training. This applies for a future fighter, transport, and even helicopter pilot. We tend to consider military pilot training as fighter pilot training. However, the reality is that armed forces have more transport and helicopter than fighter pilots. Again, due to the side-by-side cockpit, the G120TP covers the training for all future military pilots, even the ones flying drones from a container.
Who are the main operators of the G 120TP? Why do you think they have chosen G 120TP over its competitors?
The biggest operator up until now is Indonesia with 30 aircraft, followed by Mexico with 25 and the Royal Air Force in the UK with 23. Myanmar has 20 and the Royal Jordanian Air Force 16. But even lower numbers like 10 in Argentina, 7 in the USA with CAE for the US Army training and 5 in our own Joint Pilot Academy Grob (JPAG) for the US Air Force in Texas are making a difference in their operation since the versatility of the G120TP that I have mentioned allows them to do all the training they need. This is further emphasized by the fact the Empire Test Pilots School (ETPS) at RAF Boscomb Down in the UK delivers first class training for future test pilots and flight test engineers on the G120TP.
You have also developed efficient training programs for the G 120TP called Grob Training Systems. Can you describe the training process and why you think it is an important part of your service/selling point?
From my explanation you can see that Grob Aircraft SE comes from an aircraft manufacturer background. We are an aircraft manufacturer but also more than that. We deliver all the necessary training around the aircraft, not just for the pilots but also for the maintenance engineers. When we deal with a new Grob user we usually have to train the maintenance engineers as well as they have not worked on composite aircraft before. So we provide all the different types of training including composite repairs. Also, the cockpit technology is a new experience for them. So we also provide the know-how required to work on the avionics and all the other systems as well.
For the pilot training, we have developed the G120TP Training System. This system consists of Computer Based Training, Virtual and Augmented Reality, a desktop trainer for the EFIS and several different simulation levels (Part task trainers, Egress Trainer) with the G120TP Simulator at the top end. The Sim features a 300×155° dome visual system which is pretty unique in this aircraft size. The visual system is available in a modular configuration so that it may be tailored to the end customers’ needs and budgets. A very important feature of the training system is the Mission support system. It allows us to plan, brief, fly and debrief the sortie (a training flight, editor’s note) with data derived from the Flight Data Recorder (FDR). The FDR is not mandatory for the size and weight of the G120TP but every user has chosen to install that option in order to have an unbiased record of the flight for debriefing. The FDR also features audio recording and can be augmented with the optional video system.
The debriefing of a sortie is crucial for the progress of the students. The more lessons you learn in a sortie (also by making mistakes) the more you gain from it. But, if nobody points at your mistakes or has no means of getting the message to the student it is a wasted sortie. The FDR also enhances Flight Safety and Discipline since the instructors are “supervised“ as well during their flying.
How do you see global air forces developing? What are the future needs and key market trends? Where do you see the main challenges for military trainer manufacturers?
One trend is definitely the overall reduction in numbers of military pilots and airframes. Civil aviation however grows steadily and demands airspace for use. Some military aircraft are not equipped to be operated together with civil aircraft in the same air space. At least for the transport aircraft that fly on the same airways as the airlines the military aircraft need to be compliant with Global Air Traffic Management. This is in regard to the installed equipment and also in turn for the pilots to be trained to those standards. The sooner you have these training capabilities, i.e. training aircraft available, the cheaper it is to do the training. An example for this is the Multi Crew Coordination training (MCC). You need a cockpit that is equipped with dual controls and dual FMS. Years ago, this training was typically done on a Boeing 737 and is now available in a G120TP. This downloading has also a limit. It doesn‘t make sense to download tasks from higher level trainers if the outcome would be negative training. An example is weapons training. The challenge is to have the correct and original interfaces available in the cockpit you want to download it to. When you don’t have the exact buttons to push as in the fighter it doesn’t make much sense to train it the wrong way. Humans learn best the first time. So it is better to get it right the first time, otherwise you spend a lot of time relearning it. Also, offloading tasks to the Sim has limitations in the stage of training where the G120TP is used. In my personal experience, about 30 % Sim and 70 % flying is a good mix. The focus on the simulation will be more in the beginning and then blending in with the flying later on. In the beginning, it is actually about 75% Sim and 25% in aircraft to have them prepared properly for flying. But the students need to be in the air for the majority of the training.
Grob Aircraft has already a strong position in the market. What is your vision for the future?
We want to expand the customer base but also to offer more aircraft and training services to existing customers. If you look at the world map we still have some empty spots that we would like to fill. Improvements on the G520 with the G520NG for the special mission aircraft market and new aircraft models are also in the pipeline. I cannot disclose too much here but something like a “small transport“ aircraft completely made of composite is still missing in the market.
Thomas “Tom” Reinert (*1972)
Tom was born and raised in the state of Saarland, Germany, right in the middle between many US and German Air Force bases. He wanted to be a pilot all his life. In 1992, he joined the German Luftwaffe and from there on his journey started. He had a successful career as a military pilot, flying mainly Tornado in various roles (IDS, ECR) and also as Instructor Pilot for Tornado, gaining a Master of Aeronautical Science at Embry-Riddle Aeronautical University in 2010. He retired from German Luftwaffe in 2012. Today he is Test and Chief Instructor pilot at Grob Aircraft SE with over 5,300 flight hours.
Photo: Grob Aircraft SE, Rolls Royce