company history
A history of relentless innovation
The founding of Radial Engines Ltd in 1981 can only be described as a hobby that got out of control.  Steve Curry had dreamed about owning a Golden Age biplane since his childhood in the early 1950s.  His dad had often taken him on Sunday afternoon excursions to little grass strips where he had climbed on derelict Wacos, Alexander Eaglerocks , and Travel Airs parked out in the weeds.  While his friends built models of F86s and F100s, Steve was busy building Jennys and DH4s.  Twenty years later found Steve repeating those Sunday afternoon airport adventures with his own kids,
Josh, Caleb & Hannah Curry circa 1978
while still wondering if there was an antique airplane in his future.  His big chance came in the late 1970s when he was able to trade a 1950 Ford coupe for a derelict Stearman duster in Kansas.
With help from his young sons Josh and Caleb,
Josh in the Stearman
the Stearman was disassembled, and repairs were begun.  The nine-cylinder Lycoming engine looked intriguing, so even though overhauling an engine is not the best place to start on a years-long aircraft restoration project, Steve moved the engine to the front burner and after a few months had it finished and ready to test.  A test stand was fabricated and the seven hour test run went off without a hitch
First R680 overhaul on the test stand
In the meantime, Steve had purchased a few Allison V-1710 P-38 engines from a nearby junk yard at scrap price.  These were disassembled, again with help from his boys.
Caleb and an Allison
Josh and an Allison
These Allisons were sold one part at a time to overhaul shops which by then were having difficulty finding V-1710 parts.
With the success of that first Lycoming R680 came requests for engine overhauls from other antique aircraft restorers.  What had started as a part time hobby was starting to feel like a real business.  So, in mid-1981 Steve leased industrial space in Oklahoma City and hung out the shingle for Steve Curry Aircraft, forerunner of Radial Engines, Ltd.
Steve Curry & Ken Kennedy at the first shop
The boys continued to help after school and in 1986 the first paid employee came on board.  By this time there was a two year backlog of engine overhaul work, so a search began for a location outside the city where engines could be run without bothering the neighbors.
The decision was made in early 1988 to make application with the FAA for Radial Engines Ltd to become an FAA Certified Repair Station, and on April 22, 1988 REL became Repair Station RAQR194K.  Later that year an original Land Run of 1889 homestead located twenty miles north of the City was purchased, and an outbuilding was converted into an engine shop
The shop at the homestead
In the late 1980s the National Biplane Association began holding its Biplane Expos in Bartlesville, OK, and Radial Engines was one of the first vendors attending.
Steve, Abby, & the display at the Biplane Expo
That fly in was not only an opportunity for REL to showcase their engines, it also became for the Currys a family vacation each year.
REL soon outgrew the original shop building as employees were added, so the building was expanded in 1994 and then again in 1996.  By 2002 the roster had grown to 17 employees, and REL had become the premier repair station specializing in the overhaul and maintenance of small radial engines.
Radial Engines Ltd crew circa 2002
In 2003 during a visit to the shop, Aaron Higley, one of  the REL customers, told an interesting story.  It seems that before WWII Aaron had grown up only two miles from the REL facility on land still known as the old Higley Homestead.  Aaron had left home to enter the Navy when the War broke out and afterwards went to work at Lockheed in Kelly Johnson’s Skunk Works.  There he had been an engineer on the SR-71 project and had traveled the world troubleshooting that aircraft.
Now Aaron was retired, but had long harbored a dream of building a little airport on the homestead.  His question to Steve and Caleb was, “If I built a grass runway and hangar there, would REL move its facility there?”  It did not take long to see the opportunity that Aaron was presenting, so over the next two years a runway was graded and planted, and a 22,000 square foot hangar was constructed.  In keeping with the vision of a vintage aerodrome, a round top façade was added to the building to mimic the hangars of the 1930s.
Completed hangar and tower at Higley Field
REL hangar construction
Aaron lived to see his dream aerodrome built but passed away at 92 in 2011.  The airport is named Higley Field in his honor and REL purchased the airport from his estate in 2016.  More construction photos can be found here.
Settled into its new home on Higley Field, REL turned its attention to making improvements and upgrades to the engines they maintained.  Stainless steel exhaust valve seats, improved shielded wiring harnesses, baffle modifications, and intake pipe drains all received FAA approval.  But the most ambitious project was fitting Bendix Precision fuel injection to multiple radial engines and airframes.
Fuel Injection fuel flow tests on the Stearman
Ultimately the Jacobs R755A2, R755B2, L6MB, and the Pratt & Whitney R985 engines received approval, as well as STCs for the Cessna 195, Waco YMF-5, Boeing Stearman, G-164 Ag Cat, and De Havilland Beaver aircraft.  More about these projects can be found here.
In early 2005 REL was contacted by a woman in Idaho who said that she had some radial engines for sale that her father, Eugene Frank, had collected.  Caleb flew to Idaho to investigate, but what he found was much more than just a few engines.  Twenty-six vintage airplanes in various stages of disassembly were scattered through four hangars.  
One of Gene Frank’s N3Ns
Wacos, Eaglerocks, N3Ns, Birds, Jennys, and a host of very rare aircraft and engines were hidden there.  Caleb negotiated a sales contract with her, and over the next few months the airplane projects were identified, dusted off, photographed, and ultimately sold.  The story of that adventure is here and more photos are here.  Since that time REL has gotten involved several times helping families to sell aviation estates.
Much of what Steve and Caleb found themselves doing in the early 2000s was answering calls from aircraft owners and mechanics with questions about how to operate and maintain their engines.  So, beginning with the Jacobs engine, then moving to the W670 Continental and R680 Lycoming, maintenance videos were made answering many of those questions.
R680 Lycoming maintenance DVD
Originally released as VHSs and later DVDs, these videos have now been broken into ten to fifteen minute chapters and are posted on the REL YouTube channel.  They can be accessed here. For those wanting DVDs, we can still supply that format.
Something that especially bothered Steve was the mountain of rejected parts that were generated during the overhaul of engines.  He just could not bring himself to scrap them or throw them away.  Solely by design, the radial engine is a thing of symmetry and beauty:  multiple cylinders situated radially around a central case and crankshaft.  There just had to be something that could be done with all that scrap (and aviation history) that did not involve simply melting it down.
Then, one day a customer came to see the progress on his engine.  He was so impressed by the beauty of it that he asked if a coffee table could be made of rejected parts but detailed exactly as his engine.  The table was built and delivered.
Continental W670 display table
But it brought up a question:  would there be a market for more of these tables?  Another table was fabricated and taken to display at Oshkosh.  Two hundred engine tables later the question has been answered!  In addition to tables, ceiling fans, wall hanging engines, and a host of other designs have been built.  More about that here.
During 2011 two more needs presented themselves.  First, the accessory overhaul shops could no longer find fuel pump seals for the 200- and 400-gallon fuel pumps.  The 200-gallon pump is an absolute necessity for the Cessna 195 and several other applications.  
REL PMA’d Pesco fuel pump seal
REL was able to develop the tooling and resources to manufacture those seals and add them to their PMA.  Additionally, an electronic ignition system was developed for the Jacobs and some models of Continental W670 engine.  You can see the details here.
During WWII it was common for radial engines to be utilized in tanks, landing craft, and motorized guns.  It is probably not surprising that military vehicle collectors would need engines and ultimately would contact REL for help.  So in addition to aircraft engines, REL is now a major supplier of engines for other WWII vehicles
W670 powered Stuart light tank
Then, in 2017, REL was contacted by the FAA Technical Center to see if there would be interest in getting involved in testing experimental fuels in radial engines for the FAA’s Piston Aircraft Fuel Initiative (PAFI) program.  PAFI would have as its goal the replacement of 100LL fuel with one or more newly developed unleaded fuels.  REL was granted a contract and infrastructure construction was begun to accomplish that end.
PAFI dynamometer test cell under construction
More about that project here.
Now, Radial Engines Ltd finds itself well into its fourth decade of maintaining engines and aircraft from the Golden Age of Aviation.  Well over a thousand engines have been overhauled and many rare vintage aircraft are nearing 100 years of age, still reliably powered by REL engines.  As REL approaches its half century mark the goals remain the same as they did in the beginning:  building the most reliable engine possible under the banner of the REL motto, “a history of relentless innovation”.