Rotor Cooling

[Charles Wilson]

This is a continuation of a Topic brought on GrosOurs New Member welcome. If it goes too far astray, let me know. (I have "Smilies disabled" but they still appear. Measures have been taken)1. When Curtiss-Wright began their development of the Rotary, their first engine, the IRC-6, was scaled up from the NSU work. The single chamber volume was 60 cubic inches, about 1 liter. There is an extremely interesting pair of sentences concerning the motor in Norbye's book, The Wankel Engine, p. 202 (emphasis added):"A nodular cast-iron rotor was designed and used experimentally. It performed satisfactorily, under less stringent conditions, with no internal rotor coooling at all."Huge amounts of cash and R&D time have been spent on Rotor Coooling, especially coooling the rotor with oil and as you look at the RE-5, you can see the results of this line of thought:Plain Bearing.Plates and Seals to keep the oil in without massive oil leaksOil CooolingHigh Pressure oil pumpWeight. Lots and lots of weight.2. If the RE-5 was developed from the NSU line ('N it was), this solution was off-the-shelf technology from the automotive side of the engine. However:SAE 770190 "Suzuki Production Rotary Engine...":"As regards rotor cooling, the feasibility of fresh gas coooling was checked but it turned out that the mean effective pressure was hard to raise to the needed level..."I would love to see the development pictures on this one. Here is the proverbial "Fork in the Road". Did Suzuki get NSU data and Fichtel and Sachs engines? At this time, for the oil coooled Rotors, the oil was sprayed by a jet into the rotor into "cells" The oil sloshed around in a clever manner. Eventually the oil would "migrate" to a collector on the other side of the rotor. Then, off to the oil radiator. It's more complicated than it sounds and it sounds fairly complicated.NSU then spent an enormous amount of cash to develop the "Thin Film Principle" on the 871 motor, eliminating the need for all of that oil to slosh around. There are still a few 871 engines - somewhere. Few people cared.This was the end of the road for the RE-5 development. It worked. The engine was bulletproof, even if the result was compromised (Haven't even mentioned the exhaust). Meanwhile, another small company made gigantic strides with the Rotary. Norton used caged roller bearings and an air coooled rotor. The results were astonishing. The rotor got coooled, friction was reduced to very low levels and it was VERY light. Horsepower was WAY up compared to the original Fichtel & Sachs motor, on which the Norton M/C engine was based. It was rock solid.3. So what was different? Everyone on this site should know. The gas circulating through the rotors was diverted to a Plenum, the carburetors were realigned and all sorts of good things happened. The volumetric efficiency still suffered a bit but compared with machining several plates with various sealing elements placed in grooves and such, it ended up as a wonderful PRODUCTION solution.4. 'Zat it? No. Consider SAE 770044, "An Update of the Direct Injected Stratified Charge Rotary...". Every Rotary Kook should have this Paper ("Hrr-mmmph...As well as 821068 "Development of the Norton Rotary Motorcycle Engine", thank you..."). Curtiss-Wright is developing Direct Injection in their Big Rotaries. They begin looking at Rotor Cavity design and they manufacture rotors that allow inserts to be screwed into the rotors - It's easier to machine a single plate than it is to produce rotors. BIG NEWS: Emissions go way down! Remember what Norbye reported? "The engine performed with no rotor coooling at all". Now, you can't just Not-Coool the rotor so what does this mean? If you can restrict heat transfer from the rotor face to the rotor proper, all sorts of goodies accrue. Call it the "Hot Rotor". One would even hope that volumetric efficiency might improve incrementally. Less heat to the coooling rotor gas, more volumetric efficiency. Less heat to the roller bearings. 'N so on.5. Norton already tried this. They were called "Hand Grenade Rotaries" because the screwed together rotor faces sheared the screws. OK. Back to the drawing board. However, a question arises, Richard: Did anyone ever test one of these HG Rotaries for emissions? Would be very interesting to see. Modern ignition technology would take care possible pre-ignition problems.Rotor Coooling has taken huge amount of cash on the Big Engine automotive side. The Norton record, however, is sterling. A wonderful accomplishment. It would be nice to see this work continue. But we knew that already.CW

[GrosOurs]

Very interesting. And this made me discover that several books about the rotary engine exist (technique and history). I think I will buy some of them to discover new things about this very astonishing technical solution.GrosOurs