Photo courtesy of Brad Groom.
Photo courtesy of Brad Groom.
What is round and made of metal, comes from Australia, and many aviation people enjoy it? A can of Fosters? Could be, but I’m thinking engines as in the Rotec radial engine. And if you haven’t seen one of these you are truly missing one of the most aesthetic looking aircraft engines that come with a high degree of performance and reliability that brings back the golden age of aircraft engines.
This article is not about a big manufacturing company but about the little shop that could and how it succeeded in supplying the aviation world with two radial engines.
Another set of brothers
Rotec Engineering Pty. Ltd. was established in the year 2000 but even before that the ground work was being laid down for this company. Just like the Wright brothers made a good team in aviation so did the Chernikeeff brothers, Matthew and Paul.
It started around 1997 when Paul’s first radial design seven-cylinder 350cc radial engine was made for his scale model aircraft which drew great interest from the Australian aviation community. The brothers were taken by surprise by all the attention and were asked to make a larger engine. Soon they were invited to the Caloolture air show in Queensland to display and run their radial engine. Well, every time they started it up they were flocked by people and soon were out of brochures about the engine.
Next was to try to find someone to fit one of their engines on for test flights. The process of ground testing and fine tuning with a series of dynamometer tests was completed and the next step was flying. Slepcev Aviation accepted this challenge and installed the R2800 on a specially modified Storch called the “Criquet” named after the French radial powered version of the Fieseler design. Mr. Slepcev was very valuable as he relayed important information back to Rotec Engineering for evaluation.
As mentioned, this is a small company with Matthew, a toolmaker by trade with an operational background in CNC (computer numerically control) machinist, and Paul, a qualified automotive electrician and a skilled machinist with a passion for radial engine design and construction. With the help of a qualified aeronautical engineer, Bill Whitney, this team is very capable of manufacturing some great radial engines. Round this out with an individual with a B.S.c. with honors’ combined with many years of business, their “Dad” Jim Chernikeeff brings another great component to the team that navigates the business.
The R2800 radial engine
The R2800 is the seven-cylinder radial engine that started this company and helps it expand and deliver the engines around the world. Dry weight of this engine is 224.4 pounds which produces 110 horsepower at 3,600 rpm via 3:2 planetary reduction gearbox.
It was only a matter of time until the aviation community desired another larger engine and Rotec was asked and looked upon to fill this need. So far, this company was trying hard to pay off bank loans. Exploring another engine was not in the cards at this time, but over the 2003 Christmas break Paul produced the first set of design drawings. Everyone at Rotec agreed this was viable but what about funding? As the word got out that Rotec was trying to build a nine-cylinder radial engine, some individuals committed to purchasing these engines, which helped in the decision making to move forward.
By Jan. 18, 2005 the Rotec R3600 went into production. Basically, this engine is the same as the R2800 with two more cylinders and 40 more horsepower making this engine perfect for a lot of builders that are building WWI aircraft like the Nieuport, Sopwith, Fokker DR1, aircraft like the Hatz, and people wanting a 150-hp radial vs. a 110-hp engine.
We mentioned before the horsepower and weight of the R2800 but let’s get into some other technical information.
The ignition system consists of two auto type spark plugs per cylinder that independently fire by both a single self-energized magneto and a Hall-effect 12-volt electronic ignition system. This system in effect eliminates total failure of the ignition system when used in tandem. The timing is fixed at 22 degrees BTDC. An electric 12-volt starter motor, which is mounted in the rear, has a built-in solenoid for reliable engagement and cranking. Also rear mounted is a 35-amp alternator with a built-in voltage regulator.
The fuel is supplied to the engine by an engine-driven mechanical fuel pump, an electric fuel pump (which you need to purchase) and then configure both in series. The carburetor is a single Bing 40mm constant compression that has very good automatic altitude compensating mixture control that gives a smooth delivery of power. A conventional valve train is utilized with two per cylinder with dual row cam rings and roller tappets for smooth valve movements by a pushrod and 1:1 rocker transmission. There is a dry sump lubrication via geared oil pressure primary and secondary scavenge pumps.
The propeller hub is driven by a precision ground and matched taper. The propeller flange specifications are standard and are the same as are used for a Rotax 912 Series. The gearing is by a planetary speed reduction unit at a ratio of 3:2 engine rpm: prop rpm. The propeller’s rpm fixed with a 76” diameter x 51” is rated at 2,400 rpm.
The minimum octane is 97 RON or 100LL aviation or high octane mogas is recommended. Compression ratio of 8.5:1 is standard. Fuel consumption with avgas 100LL or high octane mogas is 5.8 gal./hour at 80 percent power. Rotec recommends using a high quality, major brand, four-stroke motorcycle oil, like Pennzoil motorcycle motor oil SAE 20W-50 or Valvoline Dura Blend Synthetic SAE 10W-40. Rotec recommends time between overhaul (TBO) of 1,000 hours.
Beware of corrosion
Builders of experimental aircraft like to have all their parts ready for installation as needed and not have to wait for them to be delivered. This is also true with the engine and sometimes they are delivered and end up sitting in a corner waiting to be installed. This practice will eventually damage your new Rotec engine as corrosion will start. Remember rust never sleeps. In the manual, corrosion protection is outlined but Rotec also has additional recommendations that must be followed if the engines are not in use or are in storage. It is very important to take the necessary steps Rotec outlines to protect your investment.
On a personal note when I was employed at the Aviation Institute of Maintenance in Chesapeake, VA, I would send emails with technical questions about the R3600 we purchased for our WWI student project which was to build a Nieuport 24 aircraft using the Redfern plans. Rotec was very helpful with all our questions and provided the technical answers when we needed help. We even purchased other items like antique looking gauges and a propeller from Rotec.
With hundreds of these engines sold it won’t be long before you see one of these engines at your nearby air show and hopefully you will hear that distinctive sound of a radial engine in flight and maybe just maybe you’ll have a Fosters in your hand also. How great would that be?
Brad Groom has been an aviation enthusiast and an educator for more than 25 years. He has served in the U.S. Air Force, spent many years teaching foreign nationals how to maintain and troubleshoot aircraft for a defense contractor, part of the Navy Adversary Program Quality Assurance, and was employed in a FAA Part 147 school as an instructor and a manager. Currently he is the program coordinator for Centura College’s online aviation maintenance management degree program. He holds an Airframe and Powerplant certificate and a bachelor degree in technical education.