Cox model engine
On February 7, 2009, Estes Industries stopped producing Cox engines and sold all of their remaining inventory – mainly spare parts – to several private buyers from Canada and the US.
After the bankruptcy of Hobbico in 2019, MECOA (Model Engine Corp of America) purchased Cox Hobbies in its entirety from Estes Corporation.
The self ignition is due to the heat produced from the compression of the air/fuel mix, and the catalytic reaction between the platinum element in the glow plug and the methanol in the fuel.
(The Cox engines employed a starting spring which kept fingers free of the propeller and generally ensured correct rotational direction.)
The piston and cylinder were made from mild steel bar stock and the crankcase and fuel tank were cast aluminum.
The classic Babe Bee was the first engine Cox produced with an extruded machined anodized bar stock aluminum crankcase.
This engine was also supplied in thousands of RTF (Ready to Fly) airplanes sold in department stores worldwide.
It is a Babe Bee with a muffler, twin bypass port cylinder with no sub piston induction and a high compression (#1702) glow head.
[15] The engine was designed for power launching Radio Controlled Gliders and had a red tank with a blue spinner.
The engine came after the Babe Bee and looks very similar with its anodized, machined extruded aluminum crank case and fuel tank.
According to an Aeromodeller engine test done in August 1974 the Black Widow on 25% Nitro output power was 0.08 bhp (60 watts) at 15,000 rpm with a max.
[17] The Killer Bee was an attempt at making a fast reed valve 049 engine from information that had been learned over the years of racing and competition.
It had a tapered cylinder with SPI and lighter piston similar to the Tee Dee, a stronger balanced crankshaft and a new reed valve shape.
[18] The Killer Bee 051 existed so that modelers could fly the same plane in two competition classes (i.e. A and 1/2A) simply by changing the engine.
It was designed by Bill Atwood who had been hired by Cox specifically to produce the Tee Dee line of competition engines.
[21] (Note: The modern Norvel AME 049 engine which has an aluminum piston running in a ceramic coated cylinder, outputs .14 bhp (100 watts)@ 20,000 rpm).
The 051 was simply a Class A version of the engine, physically the same on the outside only the bore was different and the piston had a small groove in the skirt to bleed off just enough power to exactly equal an 049 so no trim changes would be required to free flight models (this groove also visually differentiates the 051 from the 049 but this was of secondary importance).
It immediately became the engine to use in FAI FF with vastly higher performance than the Olympic, which had supplanted the European diesels used at the time.
Fritz Schneeberger (Switzerland) won the FAI free flight world championships using a Tee Dee .15 in 1961.
[25] They proved fragile however, particularly the thin-wall cylinder, and ball-and-socket connecting rod, and were replaced by beefed-up versions (as noted below).
The cylinder was a non-tapered twin bypass with no boost ports (like the one used on the Black Widow), the crankshaft was drilled out rather than milled like the Tee Dee, and the carb body was a one-piece unit with a conventional needle valve and spray bar.
The horseshoe backplate had additional mounting holes drilled in the plate allowed fitting to after market and kit aircraft.
It also had a spring starter and red aluminum spinner, and the fuel intake tube was extended below the plastic backplate.
Rear reed valve .15 sized version of the Space Hopper Sportsman with twin ball races - designed for FAI Power FF event Prototyped only (50 made by Bill Atwood) They were handed out to various people to try out and as such a few still exist today and appear from time to time for sale at swap meets and on eBay.
All early cylinders had a thin wall which was later found to need improvement because they bent easily in a crash or when trying to undo with a Cox wrench.
The early engines that were produced before 1957 had a light alloy piston rod which is retained in its socket by a slotted steel retaining cup which in turn is held in place by a steel circlip located in a shallow groove in the interior piston wall.
The advantage of this latter set-up was that it simplified assembly and the bearing could be re-set to take up play using a suitable "reset" tool to re-swage the cup.
Sometimes, especially with engines that have had a lot of use, the piston / conrod ball socket joint is very loose and will adversely affect performance.
They found under the heavier torque loads caused by running diesel fuel, that the pins would break also; hence they produced their own killer crank.
Claims are that Mylar and Teflon are lighter and make the engine easier to start and go faster, but they do not last as long as the stainless ones.
