Trailing Channel Rotors

[Charles Wilson]

For the esteemed Richard Negus-I remember seeing a picture of RN holding a rotor that had a channel running from the back of the Rotor Pocket to the trailing end of the Rotor.What was the performance result of this enhancement?Still a lot of unexplored territory in Pocket design.Did it work?Thank you,Charles

[Richard Negus]

Hi Charles,As you may be aware, that relief on the trailing flank of 9:1 compression rotors was introduced in about 1988 as an antidote to what was alleged by the Norton 'aero' development team to be detonation in their engines. Except for accuracy of dynamic balancing, the rotor was common between aero and motorcycle engines so the latter gained this feature also.I understood at the time that detonation was said to be the cause of side plate scoring. Whether that is true may be open to discussion, but hard-coating the plates is certainly a proven cure.Early single rotor aero engines made by Mid-West Engines had relieved-flank rotors and still suffered plate wear. They adopted full-face molybdenum, curing the wear problem and then had Norton make a batch of non-relieved rotors. They carried out back-to-back testing and demonstrated a slight power improvement with the non-relieved rotor. I don't have any figures now to support that.Mid-West, now Austro Engine GmbH, continues to use the non-relieved rotor.Not having seen either a UAV Engines or Rotron rotor, I don't know whether the relief continues there.An amusing aside is that Bob Rowley had a cardboard fish, coloured red, in his office. I have a feeling that the 'red herring' may have made an appearance at meetings when the flank relief was proposed .

[Charles Wilson]

Thank you!Here is a thumbnail of the (Current?) Rotron Rotor: http://www.rotronuav.com/news/article/r ... /Beautiful piece of work! In the sliver of the Rotor Face that you can see, there does not appear to be a trailing channel.If one purpose of the Pocket is to "shape" the charge plume as it roars towards the front of the rotor face then a trailing channel would provide an orderly route for the squished gasses in the trailing end to move forward.But good ol' science is the best answer and if the total amount of pocket volume was the same in both channel and non-channel rotors and the non-channel rotors produced better results then that settles that - until another designer comes along from another idea.Curtiss-Wright pioneered the Direct Injection rotary and there was no detonation for the simple reason that there was no fuel to detonate until the injectors did their job. They also used screw-on rotor surfaces with insulated air gaps to restrict heat transfer. HC emissions were drastically reduced. Norton experimented with bolted on rotor faces as well. They were called "Hand Grenade Rotaries" as I recall reading.Research proceeds...Charles

[Wayne]

Hi CharlesThe early 10 to 1 race rotors had a machiened secondary traling channel or a gouge hand filed about 1/2 wide. the final duckhams rotors had a central pocket with no trailing channel making the rotors unhanded.Regards Wayne

[Charles Wilson]

Literally just found this one:http://etd.ohiolink.edu/view.cgi?acc_nu ... 13594631If you have a look at this, consider the Rotor Pocket shown.Somewhere in my files of forgotten stuff is a rotor profile of the Audi 871 which shows the same type of notch."We're not done with this patient yet, Doctor..."Thanx,Charles

[Charles Wilson]

Here's a Trailing Channel Rotor (and a coupla' more) from the Curtiss-Wright days.