Rotary engine vs. standard radial

[Ed]

Was there an advantage to using the
rotary engine over the standard radial
engine? It seems to me that the rotary
was quite troublesome to operate.
I don't think we guys wouldn't have
appreciated one of those things twirling
around in the engine compartment of our
M4 tank.

[Kory Clark]

One thing i was wondering did all engines spew castor oil? Or were rotaries more prone?

In flight that gyroscopic movement might be a pain, but didn't it help the camel manuver to the right fast like a snake? Does one have the ability to take more damage?

[Brad]

Hi The advantage to rotary's is the power to weight ratio. using largly steel components it was hard to beat in those days. Only rotary's spewed castoroil because they were the only engines using it.

[Ron_F]

Right, the rotaries only used castor oil for cooling/lubrication of the engine parts. same as a 2 stroke dirt bike uses a mix of gas and oil for lube, even tho the rotaries were still 4 strokes.

the inlines were using coolant in radiators for cooling of the engines.

another forumite noted that a pilot flying behind a rotary could definately smell the castor oil trail it left, and i think mentioned in WW1 pilots could also tell if any rotaries had passed through due to the castor smell.

they produced more power for little wieght, and the gyro effects could help in turning, ala more so the Camel.

as far as damage, i guess it would be how much damage it took. if a cylinder was shot off on a rotary, it would make it out of balance and severely effect the operation of the plane. radials would just keep on going as they were stationary.

fwiw,
Ron

[John L]

The rotary engine in a Camel allowed quick maneuvers upward to the left, but often produced a "right dive" that many pilots could not pull out of if they were low.
In machining a LeRhone rotary engine, each cylinder started out as a 97 pound billet of nickel steel and ended up a 6.5 pound finished cylinder That left a lot of chips on the floor under the Warner and Swasey turret lathe.
In that no engineer had mastered the art of dynamic balance at this point in time, most engines were run out of balance (to the standards we understand today.) But, the rotary holds one first prize even to this day: It put out more torqe per pound than any other engine. Part of the beauty of a rotary was that it was its own flywheel.
Rotary radial engines were used in automobiles, at least one of which still exists in a car collection. They were obsolete by the end of the war, but many survived to this day.
Despite what Barrett and other "ex-spurts" say, it was a remarkable engine for its time and it allowed airframe designers a new latitude in design. Like any other engine it had its good and bad features. And, it helped the Nieuport 11 and Sopwith Pup, Camel and Snipe to make an impact on aeronautics of the Great War period.

[Ed]

Thanks for all those replies guys. Oh!
One other oddity about those castor oil
burners-----the pilots swallowed a lot
of the atomized oil and I read that the
latrines were pretty busy after a flight!

[John L]

They didn't always make it to a latrine.

[joegertler]

The advantage in 1909-1918 of a rotary over a radial was cooling. Cooling of the barrels and heads of cylinders, and valves, was not sufficiently advanced in static radials until Lawrance and others came up with more sophisticated cooling fins, and materials after the war. Lawrance, of course, was reponsible for the Wright radials starting right after the war that could cool with efficiency and reliability. Prior to that,The turning of the entire engine at 1200 rpm or thereabouts directed enough air over the cylinders to get by. (But not by much)You will note earlier static radials such as the six cylinder and ten cylinder Anzanis, for example. and the earlier fan-type engines. cooling was a big problem for them in those days. could not compare to contemporary rotaries that competed.

[Dan_San_Abbott]

Ed:
The reason they used castor oil in rotaries engineit was not diluted by the gasoline or benzin. Petrolum based oils would be diluted by the fuel and could not provide sufficient lubrication to the engine. Oil consumption to fuel was 1 liter of oil to 10 liters of fuel. The consumption was two fold under pressure through galleries in the engine and atomized and mixed with the fuel in the crankcase in order to lubricate the the rod , piston and rings which wound up going out the exhaust port.
Dan-San Abbott

[leb1933@uia.net]

This topic was discussed a few weeks ago and I'll repeat a couple of points which I hope are of interest: Imagine a single cylinder crank (a lawnmower?) bolted into a vise. If you reinstall the rod and piston assembly you can obviously get only a circular motion out of the piston. There is no way the piston can go "up-and-down": Therefore there is no reciprocal motion and all those reversals of direction which put tremendous inertial loads on the piston pins and bottom ends of a conventional engine simply don't occur. Wrist pin failures and "big end" failures which all too frequently disable conventional engines are obviously not an issue: this in itself is a marvelous engineering aspect of the old classic rotaries. If the motion of the reciprocal nature isn't present you don't have to "balance it out". This means you need no heavy counterweights on the crankshaft. This absence of any balancing weight in the crank assembly is the reason the unit is significantly lighter than a radial of the same dimensions. Again a fundamental advantage to the engines of this nature. As re. "castor oil". It is not at all needed. Jim Appleby is a foremost authority around on the "rotaries". He never uses any thing other than Shell Aviation 60 with 10% STP. Moreover, castor oil will "glue up" a infrequently used engine so use of it has that added disadvantage. Modern two-stroke engines mix lubricant with fuel and don't require castor oil: Accordingly neither do the antique rotaries now running.
The "Camel" due to it's own airframe configuration, was a difficult airplane to control. Many a/c which had the rotaries were not difficult and in many cases were a delight to fly.
A friend of mine, Tony Capozzi, is tooling up for a 80 Le Rhone project. We took the finished carb to the Appleby's last week and will be going again shortly to install it and run it on one of Jim's engines.

For DSA: Tony and I will quite likely be going up for the Flayderman auction so will get together with you prior to the event. I'll e-mail you as soon as things firm up. VBR. Lee

[John L]

Shell aviation 60 and Scientifically Treated Petroleum were not around in 1910- 1919 when the rotaries were in general use. Today, certainly no engine needs castor oil because of the synthetics on the market. But in the 1940's many of us broke in our Ohlsson .60's,.23's and 19's using castor oil. We had a small, enclosed back porch. Result: same effect the Great War pilots experienced.
Hindsight is a wonderful thing for present day flyers, but, unfortunately, Andy Granatelli and a group of oil company chemists were not around during the Great War. Therefore it is reasonable to state that castor oil was a necessity. No matter what present day magicians do, radials would not run for any length of time without castor oil.
In "Aviation Engines", Victor Page devoted an entire chapter to castor oil.
And, yes, when my 1/5 scale rotary engine is completed it will not use castor oil. I can't hobble to the can as fast as I did when I was 12 or 13. Perhaps the answer would be an exhaust hood on the back porch, but castor oil will even foul up a hood in short order.

[rudder]

It looks like that with modern metals and bearings that someone could build a Rotary that would hold up reliabily and for at least 500hrs. You could use oil injection similar to what many modern 2 strokes use. With the use of modern oils I think the oil consumption rate would be greatly reduced. I think the Old Rotarys used way too much oil. Much more than I believe was needed for the job of lubrication. I think they ran about 10:1 on the oil fuel ratio. I think that could be gotten down to 50:1 or even as much as 100:1 with modern oils. These engines only turned 1200 rpm. vs. a modern engine turning 10,000+. It looks like some interpriseing individual would copy the LeRhone 9Jb and sell it to experimental Aeroplane builders.

[John L]

Perhaps if the parts were investment cast the plan would be feasible. However, the tooling costs would be a great deal more than the total projected sales of such a vertical type of item.
When I researched the LeRhone about 40 years ago, I came across an interesting disclosure in the Wright Pat museum library. The LeRhone 9cyl. rotary was experimentally altered to the configuration of a stationary radial. Oddly, without rotation, the cooling was as satisfactory as when it spun on the crankshaft. As far as I could determine, the engine under test did not have a cowl covering it.

[Steve Dorste]

John L. mentioned the use of the rotary in a car. It is interesting to note that, at least in the one I saw in a picture, the rotary engine was located inside one of the wheel/tires and directly used the rotation of the engine to drive the vehicle. Wonder how they would clutch such a thing?
Steve

[John L]

Hit the blip switch, pop the clutch in, grind the gears and pop it back out, then let off the blipper?

[Ed]

Would a centrifigal clutch or a "Fluid
Drive" coupling a la '46 Dodge work
on that rotary engine drive line?

[Dave]

The rotary engine is an amazing machine, and for its day the perfect engine for combat aircraft, but it did have its problems, some of which were breathing problems that limited power, the route from the carbuerator thru the crank, and into the crankcase, from there, it entered the cylinders either through inlet ports in the cylinder or into manifoldswhich lead to the combustion chambers. Ignition connection was another problem, these were very noisy engines due to no exaust manifolds. with all of the rotating parts there was power loss due to drag, max power per cylinder was about 11 horsepower per cyl. if more power was needed, a second row of cylinders added, but that would effect the back rows cooling, increase gyroscopic forces and add weight.

[John L]

I'm building a 9 cylinder Gnome in 1/5 scale. There was no carburettor. Petrol and oil flowed into the crankcase and were aspirated through a bypass port, atomizing in the comblustion chamber. Early engines had a crankcase intake that was an extremely righ mixture, to be diluted with air as it passed through a valve in the piston head. It was found that the occurrence of crankcase fire was too frequent, so the later engines were designed with a side bypass and fuel and oil in liquid form poured into the intake tube.