The RFB Fantrainer; Making a Basic Trainer Handle Like a Jet

March 2, 2023

In my recent video about Thailand’s RTAF-5 experimental trainer, I told how the need for that aircraft had been largely removed by the purchase of the RFB Fantrainer for the Royal Thai Air Force. And that led to a fair number of you asking what that was.

Well, I’ll tell you.

West German-based Rhein-Flugzeugbau is the sort of small and out-there aero company that we love here at Military Matters. Set up in the 1950s, they started by building one off pusher aircraft of their own design, before moving to experimenting with ducted-fan propulsion systems in the 1960s. In 1970 they thought that they recognized a potential market for a new, innovative trainer aircraft that used this design style, and this idea formed the Fantrainer.

 

As fighter aircraft became more and more complex and expensive, so did advanced military trainers, with aircraft like the Northrop T-38, the Mitsubishi T-2 and even the SEPECAT Jaguar all being developed because of the increasing leap in capabilities that new pilots had to go through to become competent to fly. This shunted the capability gap further back down the training schedule, with the leap between pilots qualifying on small piston-engine basic trainers to now literally advanced jet trainers becoming an issue, which required another class of jet trainer aircraft to be developed to bridge the gap, creating aircraft like the Dornier Alpha Jet and the British Aerospace Hawk.

But RFB figured the solution might be to build an aircraft that would combine the cheap operating costs of the basic trainer with the handling characteristics of a jet, which would mean the jump for rookie pilots would be less jarring. It would also allow air forces to potentially reduce the need to maintain different types of trainer aircraft in the qualification process.

To do this, they essentially created an aircraft with a tandem two seat cockpit which was apparently modeled on that of the Alpha Jet trainer, but with the powerplant being a ducted fan propellor behind the cockpit in the middle of the aircraft.

This helped replicate the same flying characteristics as a jet aircraft, with the weight of the powerplant being in a mid-position instead of at the front of the aircraft as with other trainers, which led for handling characteristics closer to those of service jet aircraft. And it did this at less than a tenth of the operator and fuel costs of a jet trainer, though admittedly it was much slower than such, but still gave rookie pilots an idea of how a jet would handle right from the start of his basic flying training.

I mean honestly, it sounds like a really good idea.

Despite that their primary intended potential customer, the German Luftwaffe, didn’t indicate any interest, so instead in 1973 RFB built a civilian touring version which also served as a proof-of-concept, the RFB Fanliner.

 

This caused enough interest that the German Ministry of Defense decided that there might be something worth exploring with the concept and they commissioned the construction of two prototypes in 1975 of the new Fantrainer.

The new aircraft did indeed look more like a jet than a standard propellor aircraft. Construction was mixed, with plastic and fiberglass being used for the wings and much of the cockpit, while metal was used around the engine due to the heat generated. Additionally, the aircraft had a retractable tricycle landing gear – again, an advanced feature for a basic trainer but one which any fast jet pilot would soon have to get used to.

 

RFB’s vision for the Fantrainer was that one largely common airframe could be fitted with different wing sizes and more powerful engine fits in order to accommodate basic or advanced training programs. This would allow pilots to progress in a single type that they became increasingly familiar with, meaning that as they moved onto aircraft of increasing performance the consequent leap was far less difficult as they were essentially familiar with the type throughout most of their training.

The two initial aircraft built for the German government fulfilled this concept.

The first prototype, which flew in October 1977, was fitted with twin Wankel rotary engines coupled together that produced 150hp each and had larger wings for better stability. This was intended to replace basic piston-engine trainers in air force service, providing pilots with their first powered flight training.

The second version, which flew in late May 1978 was fitted with a more powerful Allison 250 turboshaft that produced 420hp and was also used by the German military’s new Bo 105 helicopter. This version also had shorter wings for better acrobatic capability, again in line with the idea that this would act as a more advanced trainer.

In 1978 both aircraft were handed over to the Luftwaffe where they were flown off against the America Beech T-34C Turbo Mentor and the Swiss Pilatus PC-7, all in competition to be selected to replace Germany’s existing Piaggio P.149 basic trainers.

And the Fantrainer basically won, proving not just good enough against the other, better-known aircraft but much cheaper to purchase and operate. Despite the second prototype being lost in crash while on a routine transfer flight, the German government began preliminary negotiations to build thirty turbine engine aircraft.

Unfortunately for RFB, the German Air Force would a year later decide that they would have to continue to use the Piaggio for a few more years for costs reasons, as much of their pilots’ advanced training was conducted in the United States anyway.

But feedback from the Luftwaffe trials and additional suggestions convinced RFB that they could produce the Fantrainer in a format that would attract sufficient orders to be worthwhile and two basic models were built; the Fantrainer 400 and -600.

The -400 dispensed with the complicated and troublesome twin Wankel engines and settled on the Allison Model 250 C-20 turbine engine that produced 420hp, while the -600 used the more powerful C-30 that had an output of 650hp. With this the FT-600 had a top speed of around 260mph (418km/h) and an endurance of more than four hours.

As said, much slower than a jet trainer, but far cheaper to operate.

In line with the concept of the aircraft effectively being modular for ease of construction to differing requirements, the two models shared 92% commonality in their parts. They also needed to alter the fan to a five-bladed design instead of the original seven and make some other changes to the drive system because the aircraft was reputedly extremely loud.

Sources are mixed as to how successful this ultimately was, but the concept of an almost universal trainer found appeal with the Thai Air Force, and in 1982 they ordered 31 Model 400’s to be their new basic trainer and 16 of the -600s to provide training to pilots going on to eventually fly the RTAF’s new F-5E fighters, with options on another 26.

The cockpits of the Thai FT-600s were corresponding altered to be more in line with that of the F-5E, including with ejection seats fitted. The deal saw the first two made in Germany and then the rest assembled in Thailand from kits, with aircraft starting delivery in 1984 and the entering Thai service from 1987 onwards.

The Thai’s also had the fiberglass wing of their FT-400s changed to a metal construction to better stand the tropical weather in that country. Unfortunately, this proved tricky to do, and as a result the FT-400s would be later into service than the FT-600s with the RTAF and proved problematic throughout what turned out to be a short service life.

Regardless, the sale inspired RFB to additional marketing attempts, including a proposed Fantrainer 1000 for Paraguay that would have actually been a light attack aircraft. Though that came to nothing RFB persisted, launching another bid to get a contract from the West Germans in the mid-1980’s, which again failed.

At this point RFB decided that perhaps they should see about moving into the jet trainer field and teamed up with Rockwell International to take a crack at the US military’s JPATS program. This led to the creation of the Rockwell Ranger 2000, an aircraft based off the Fantrainer but now with a conventional jet engine propulsion.

This too was unsuccessful but it didn’t really matter because in 1992 RFB shut down and that largely ended the attempts to sell the Fantrainer and indeed the limited service it was seeing as the Thai’s, concerned that they would no longer be able to get parts for the type and able to buy surplus German Alpha Jets cheaply with the end of the Cold War, retired the type.

But the story of the Fantrainer isn’t quite done yet. Three are still flying and do appear at air shows in Europe on occasion.

But in addition to this, a new company formed in 2010, Fanjet Aviation, who purchased all the rights and manufacturing equipment associated for the aircraft. And they are quite keen to restart production of the Fantrainer, potentially improved with glass cockpit instrumentation, if new customers can be found.

 

So, watch this space, because the Fantrainer isn’t a completely forgotten aircraft quite yet.

 

Sources/Related:

https://fanjetaviation.com/aboutus/

https://en.wikipedia.org/wiki/RFB_Fantrainer

http://www.aeroflight.co.uk/waf/aa-eastasia/thailand/thai-manu-history3.htm#post

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