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Radial Renaissance
Radial Renaissance
Bryan McGrath
Published by brinesharks
10 May 2005
Radial Renaissance

Radial Renaissance

By Bryan McGrath

      If you have been to an air show in the last sixty years you are bound to have enjoyed the unmistakable tune of a radial engine, burbling away on the ground, or roaring overhead at low level. I was fortunate to hear one of the latest Radial engines to be developed when I visited Rotec’s factory.

Rotec’s Jim Chernikeeff kindly organised a demonstration of their non-certified 2800 radial engine at their facility in Melbourne, Australia for me recently.

The Rotec 2800 is a 7 cylinder 2800 engine developing around 110hp. The excellent design and manufacturing effort has produced a beautiful engine. It is reminiscent of the 1930’s radial engines, yet with important modern design features that improve reliability and safety.

A completed R2800 on the factory floor
awaiting test running
Much of the manufacturing of the engine occurs in-house, with all major components being milled from solid block. The engine has reduction gearing inside the front bell-housing (3:2 Engine:Prop). A dual ignition system is powered by a lightweight automotive alternator which produces enough output to power the aircraft’s electrical system, including lights and radios. The distributors are fitted to the rear of the crank case and operate independently. One is a magneto and the other, a Hall Effect electronic ignition. Both are breaker-less and require no adjustment after leaving the manufacturer. The ignition system is designed to keep the engine running in the unlikely event that one distributor fails.

The operation of the engine is completely conventional and anyone with experience using certified aero engines should have no difficulty operating the Rotec 2800. One item of note is that of course, this is a radial engine and as a result, hydraulic lock can occur when oil has had the time to drain to the lower cylinder and the pilot then attempts to start the engine. Generally, this can be alleviated by turning the prop several times with the ignition off, before a start up is attempted. A drain cock has been fitted to the latest production engines to allow operators to drain any pooling oil prior to start – thereby virtually eliminating the chance of hydraulic lock on the R2800. Jim notes that only one customer has had trouble with compression lock and the company replaced the damaged components free of charge as a sign of their good will. Once started, the engine should be idled at 1200 RPM for a few minutes, until the oil pressure is “in the green”. Rotec has found that customers who have fitted carby pre-heaters have discovered they don’t need them. The start-up reliability of the Rotec is very good, even in extremes of temperature. The carburetor itself is a Bing pressure/altitude compensating carburetor as used on other aero engines. Recommended take off power is set at 3200 RPM with a red line of 3400 RPM. It should be noted by readers that these settings are for the recommended 76 inch propeller – larger than most 110hp engines could swing. The largest propeller used by a customer to date is 83 inches with the customer reporting extremely good climb and cruise performance. The engine is rugged enough for use when conducting aerobatics, however like most radials, the carburetor does not supply fuel for sustained inverted flight. So, loops and rolls are in but prolonged inverted flying shouldn’t be attempted.

R2800s crated and ready for shipping to a
distributor in Italy
The Chernikeeffs have been overwhelmed by the interest in their modern radial. They have sold nearly 150 engines worldwide over the last five years. Rotec’s philosophy has led them to establish an agent network selecting companies who sell a range of products which complement the R2800. Rotec feel that their ideal agent is one who has a range of experience in the homebuilt and experimental field. This enables the agent to provide customers with an option of not only supplying the a R2800 but fitting it to their aircraft.

With the overwhelming number of sales, Rotec have steadily increased their production batches. They have found that most customers are submitting a 10% deposit to secure a pre-production order. The latest batch of 25 engines has already been earmarked for eager customers who have pre- ordered. Jim says that the WW1 replica movement has shown a great deal of enthusiasm for their radial. Able to swing a large propeller at a relatively low RPM (compared to other “110 hp” engines on the market) they are a safe and economical substitute for rotary engines in Sopwiths and Fokkers. Jim is in touch with customers who are building a Fokker D8, an Eindekker and several Sopwith designs. In fact, Graham Lee of the replica Nieuport fame is a Canadian Agent for Rotec engines. A full-scale Nieuport 17 should be flying soon with an R2800 pulling it aloft. Rotec have found that the homebuilders they deal with have all displayed a high level of practical knowledge and have coped with engine installation quite easily. If customers have any queries, they can contact the company by phone and talk directly to the designers of the engine, or by email for a quick response.

Some of Rotec’s CNC machinery used to create
the R2800
Rotec takes pride in their comprehensive operator’s manual which contains a great deal of information about operating the engine. Pilots who operate certified aircraft will be pleasantly surprised with how much more information is provided by Rotec, compared to larger aero-engine manufacturers. The manual also contains suggested oil system and electrical system layouts or you can download them from the Rotec website. Before a customer receives an engine, it is test run by the factory. This ensures that the engine you receive (including associated ignition and fuel system) are functioning correctly prior to shipping.

There have been very few problems with the early delivery engines. One problem that did occur, was a noisy gear within the reduction gear unit. Although not a safety issue, it was felt that customers would be happier with a quieter engine. Rotec replaced the offending part on the first five engines with one using more rugged manufacturing methods. The engine has a planned Time Between Overhaul (TBO) of 1,000 hours, although Jim pointed out that this may be extended after more data is gathered from customer engines. The company plans to conduct overhauls initially at the factory and later by trained distributors who will act as maintenance agents. With the highest customer engine at approximately 300 hours, Rotec plans to train the maintenance agents in time for the first round of overhauls. The factory overhaul however has a two week turn-around time and currently costs approximately AU$2,400 plus parts. Check out the overhaul cost of a certified engine such as a Continental O-200 and you’ll be amazed at the low cost of operating the Rotec engine.

Paul, Jim and Matthew Chernikeeff - creators
of the Rotec R2800 radial engine
Rotec has focused on the development of the R2800 for five years and has a satisfied customer base as a result. From the feedback they received, Paul and Matthew have been encouraged to consider an even bigger radial. Customers have seen the potential of a larger 150hp radial to enhance the look and performance of designs such as the Hatz Classic and the full scale pine structured Fokker DR1. Enter the R3600, a nine cylinder radial based on the design of the R2800. Paul believes it will be a highly economical replacement for the Warner Scarab engines that are currently struggling on, well past retirement age. The development of the R3600 has been progressing in Paul and Matthew’s free time, with a design now in production on the first batch of 6 engines. Experience from the R2800 and common parts will reduce the development risk of the larger radial.

Rotec had asked for people interested in the 150hp engine to assist in its production by placing a deposit for the first five pre-production engines and it is telling of their customers’ confidence in the company that 3 prospective owners of the R3600 currently operate the R2800 and another 2 have based their decision on reports from existing R2800 owners. These five customers will assist in speeding up testing of the engine by producing data from five engines at once. Rotec will ensure that before the R3600 is released that they have tested the engine to a level that satisfies them it is safe and reliable. This company understands how important their hard earned reputation is.

For more information on the Rotec radials, visit Rotec Radial Engines.

This article was originally posted on The Aerodrome in May 2005. The article and photographs are copyright the author.

By Ray Jarvis on 9 June 2006, 03:53 AM
First Rotec Radial R3600 as fitted to my Airdrome Aeroplanes Nieuport 28-C1.
Attached Images
File Type: jpg N28-C1-DSC01708.jpg (48.8 KB, 133 views)
By Machinbird on 6 August 2006, 02:35 PM
2006 Rotec Display at Oshkosh

The relatively new R3600 radial was shown again at Oshkosh. Thought I'd post some pictures of it for those interested in possibly using it in place of a rotary.

Perhaps one day they will offer a little better gear ratio on the PSRU to get the output shaft into the 1500-1600 RPM range. When you put a big piece of your life into building an aircraft, you don't want any unplanned letdowns.
Attached Images
File Type: jpg R3600frontweb.jpg (32.2 KB, 121 views)
File Type: jpg R3600DataWeb.jpg (34.7 KB, 137 views)
File Type: jpg R3600-1web.jpg (29.8 KB, 118 views)
File Type: jpg R3600Accessory-Web.jpg (24.5 KB, 113 views)
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