The Building of a Modern Denny-Righter Radioplane

Story and Photographs by Luca Mariotti

In 1984, Luca Mariotti built his first UAV by modifying an old model airplane to make some tests on recovery systems. In 1995, Mariotti became interested in vintage UAVs (then called drones) and in particular, the work of Reginald Denny and Walter H. Righter. Such was the facination with Denny's work that, in his albeit rare spare time, Mariotti is collecting data to build a flying replica of a Denny-Righter Radioplane OQ-2A.


A beautifully restored OQ-2A

Photo : National Model Aviation Museum - Click Image to Enlarge

"In the mid-1930s, radio-controlled model airplanes became the basis for the Army Air Corps' development of the aerial targets for antiaircraft gunnery training. Starting in 1935, the Radioplane Company in California developed several variations of an original design by former movie star and modeller, Reginald Denny.

The OQ-2A was successful enough to generate contracts for almost 1,000 targets in 1943. The OQ-2A was catapult-launched and was recovered under a 24-foot diameter parachute. Conventional landing gear cushioned the landing impact. After launch, gunnery target missions were flown by a ground controller using a "beep" box, so called because of the tones transmitted to the target's control system."

Western Museum of Flight

The Engine

Luca Mariotti's first step was to a locate some original Righter engines with his collection now featuring an O-15-1 (OQ-2 engine), an O-15-3 (OQ-3) and an O-45-1 (OQ-14). Star of the show is the O-15-1, (the military designation for the 2-GS-17) now beautifully restored to 'fresh from the factory' condition - truly an example of dedication and craftmanship


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

Currently Mariotti is "translating" a microfilm copy of the original OQ-2A building plans into CAD format suitable to make the parts for the replica.


OQ-2 Microfilm Plans Oct. 9, 1942
Unrestored section


OQ-2 Microfilm Plans Oct. 9, 1942, 3View
Restored by Dr Russell Naughton

Download a master [700Kb] image

Download a parachute detail [730Kb] image

Download a wing section / airfoil [850Kb] image

"The building of a replica OQ-2 will not be an easy task and an interim project could be the reconstruction of an RP-1, which was a scaled up Dennyplane."


Reginald Denny and his RP-1 'Radioplane', 1935

Photo : Righter Family Archives - Click Image to Enlarge

Download a 1500 pixel [260Kb] or 2500 pixel [500Kb] image

Restoring the Engine

Two years ago I answered an advertisement posted on Barnstormers, (a website devoted to aircraft restoration). It was for a vintage 'Righter' aircraft engine. The owners had had it in their basement since the 1950s when it was purchased by their father in a war surplus auction.

I bought engine but, when the long awaited box arrived, I was somewhat disappointed, it was in far worse condition than I expected - nevertheless it was complete and after a month spent reading up on the engine from the small amount of information available, I began the disassembly.


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

The engine was not brand new and must have run for at least several hours before being hung on the basement wall. The oil which had been simply left in the crankcase plus fifty years of inactivity had transformed it into a sticky mess that had glued everything inside the engine together.

The only thing to do was to open the plug in the crankcase and fill everything with gasoline. After a week, I was able to get some movement in the crankshaft and after another week of daily attempts, (the fear of damaging something was ever present), I succeeded in turning the propellers a half turn. The next step was to remove the front cover.


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

Being cautious, I first removed the propellers and all the nuts located along the front cover perimeter. With great surprise the cover came apart together with the rear propeller gear. The smell was quite strong but a generous cleaning with a nylon brush and a lot of gasoline made the thing a bit more manageable. The rear cover was equally as easy to remove.

The timer showed almost no signs of rust and also came apart very easily. The rear crankcase cover was stuck firmly to the rest of the engine but came awy with the help of a rubber mallet. The cylinders however, tried, (and almost succeeded), to convince me that restoration is for masochists only.


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

The pistons seemed soldered to the cylinders and every effort to separate the two couples (left and right) seemed destined to fail. Rescue came from a friend who had restored a Willys Jeep. He suggested to dump the cylinder in a tank filled with Coca Cola!. Believe or not, after two days of bathing in 'Coke', the pistons came loose from the cylinders.

Now all the pieces were ready for a major cleaning and sand blasting. The operation of sandblasting was easy and effortless, followed immediately by the painting of the crankcase parts and cylinders. The painting was performed in the open at the first light of day (5.00 am) to avoid insects and the wind.


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

Next step was to clean all the nuts, bolts and other small parts. The spark plugs were sandblasted while the carburettor was disassembled and soaked in an aluminium cleaning solution. This operation was followed by rubbing it inside and out with a clean cloth and a lot of 'elbow grease'. At this point it was time to reassemble all the parts.

The operation was almost straightforward and at the end, I found myself with a Righter O-15-1 that to all appearances, looked as if it had come straight from the factory assembly line. A small wood support was quickly assembled and the engine bolted to it, but, something was missing: the propellers.


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

The two propellers that had arrived with the engine were split along the glue line of the two layers of wood that formed each propeller and the trailing edge of the front propeller was quite damaged. After re-glueing the layers together I decided to remove the damaged parts of the trailing edge and substitute with a visually different wood to distinguish the original wood from the new one.

After a lot of sanding the propellers were painted in accordance with the aircraft's original 1940 technical manual. The engine is now complete and on show in my studio. I am very happy and proud to have made such an effort as an almost forgotten piece of aeronautic history lives again. Without these target drones and the ingenuity of how they were conceived and built, today's UAV would be only a dream.


Righter O-15-1

Photo : Luca Mariotti - Click Image to Enlarge

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