Engine Development this is the home of rotecradial
Rotec Aerosport Pty Ltd has methodically researched the radial engine concept for the home-built enthusiast for several years.
In early 1997 the first test engine – a smaller 350cc version - was built and successfully tested to prove the design concept. The engine was a success and performed flawlessly. The two men then commenced construction of the Rotec R2800, a naturally aspirated 2.8 litre direct driven, seven cylinder, pushrod, overhead valve radial engine.
In September 2000 Rotec ran the new R2800 for the first time. It was a momentous occasion as it had taken the brothers six months full time work including design & machine time, including many late nights in the shop to have the prototype ready for testing. “ People often don’t realise the enormous effort it takes to realise a project of this magnitude. We could only have achieved it on the small budget we had due to all work such as design, machining, even pattern and die work being done 100% in house”
What lay ahead for the new R2800 was months of ground testing and fine tuning including a series of dynamometer tests. These tests proved to be invaluable as the two Brothers learnt more about their exciting new creation. After an exhaustive period of ground testing Rotec Aerosport made the bold and exciting decision to begin a series of controlled flight tests.
Rotec approached “Slepcev Aviation” about the possibility of fitting one of their new engines to what is arguably one of the safest aircraft ever built, the well known “Slepcev Storch”. Nestor Slepcev was enthusiastic, he liked what he saw and was prepared to give the new engine a go. He and his team pulled out all stops to fit the R2800 to a specially modified Storch called the “Criquet” So named after the French radial powered version of the Fieseler design.
The Rotec R2800 first took to the air on 1st of December 2000 on what was to begin a series of flight tests conducted by Slepcev Aviation and Rotec Aerosport . The test flight was a success and there was a real sense of achievement once the engine took off and gracefully flew around above with that unmistakable radial sound. The two companies kept in close communication throughout this period and Mr Slepcev was invaluable as he relayed important data back to Rotec Aerosport for evaluation.
After some months and around 30 hours of flight testing a decision was made by Rotec to develop a Propeller Speed Reduction Unit (PSRU) to further enhance the performance and flexibility of the, at that time, direct driven unit.
It was apparent that the R2800 despite its good direct drive characteristics could benefit from a small amount of propeller speed reduction as is the case with most small capacity engines. Rotec Aerosport spent the next period designing and manufacturing their new planetary PSRU which was carefully designed to fit neatly into front nose with minimal disruption to the out side dimensions. They called on the help of well known Australian aero-engineer Bill Whitney to do some calculations regarding the new design. “Bill is simply the best, we are in debt to him, few have his knowledge about all facets of aviation dynamics, he has been very generous in his willingness to help our new company get ahead particularly regarding technical issues”.
The (PRSU) as mentioned earlier is in planetary configuration, at a reduction ratio of 3:2 so engine revs are relatively low when compared to the high revving ratios other manufactures employ.” They are literally trying to wring the last drop of HP from their small capacity engines”. Ratios approaching 4:1 are not uncommon amongst some manufactures.
The first tests on the new geared R2800 proved to be nothing short of a revelation; the propeller diameter went from the direct drive 68” to 76” with more pitch than before. The PSRU had allowed the R2800 to realise more potential as the engine had ‘unloaded’, the propeller range had increased dramatically allowing for more user flexibility.
The R2800 was delivered back to “Slepcev Aviation” for continued testing. Their response was as expected, “Fantastic” The R2800 was now in a class of its own when it came to hauling around aircraft with high parasitic drag such as the Storch and popular Biplane and the like.
Continued PSRU testing and the recent introduction of a fully scavenged lubrication system including remote mounted oil tank. Also a revision of the push rod tubes which has made an improvement in the oil leak department. These have been the most recent inclusions. All engines now come standard with these features as has been the case with all engines produced in recent production runs, including retro fits to existing units.
As an ongoing commitment towards achieving a product of the highest quality Rotec Aerosport will leave no stone unturned in it's quest for safety and dependability via methodical testing and performance evaluation.
Major overhauls are to be carried out by Rotec Aerosport Pty Ltd until qualified distributors / servicemen are appointed. With the exception of the cast rocker covers and intake manifold, all engine parts are machined from solid metal by CNC (computer numerically controlled) machine tools which results in parts with incredible structural integrity in comparison to the inconsistent nature of castings.
For a given capacity, the radial configuration is arguably the most effective for hauling around big props at low efficient RPM. High torque ratings have always been associated with the radial engine. In layman’s terms this is the result of good bore stroke ratio, low master and link rod angles resulting in superior transmission of cylinder pressure to the crankshaft with all rods acting on a single crank journal. The radial crankshaft is also very short and sturdy when compared to its long spindly inline and flat counterparts and, as a result, does not suffer from torsional distortion or excessive friction caused by the accumulation of many plain bearings.
All telling reasons why the radial engine was often described as “unstoppable” due to its robust nature it dominated the world of piston aero engine construction and was the configuration of choice right up to the introduction of the gas turbine engine.
And also, all telling reasons why you should consider a Rotec radial engine for your aircraft. In doing so make sure you get the genuine product. Click here to make contact with us.
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