flyrotary@lancaironline.net Mailing List Archive

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Kelly, I don't recall any direct evidence of anyone running mismatch rotors, but certainly they must be carefully matched with the correct counterweights. All the parts I have used are from 1986 6-port motors, I carefully checked the rotor Ken Powell gave me to make sure it was the same weight and compression ratio as the other, and correct for my motor. I don't know if there is a weight difference between single spring and dual spring and seal combination that could be measured. The single spring seal itself would be heavier, but would not have the weight of the second spring. That would make the resonant frequency different between the two, but I wonder how or if resonance in the seals in one rotor could affect the other. Who knows, maybe that is all or part of the reason for the chatter marks.

Chuck

Chuck,

   This may be a stretch of my imagination but has there been any mention

on this forum of what happens internally to the Rotary if mismatched rotors

and / or counterweights are used ? Obviously the engine will not be as smooth

and a vibration encountered........The question is what happens internally at

continuous high rpm........Could such an unbalance such as this set off a high

frequency seal chatter ?

   Not saying that you have this problem Chuck but it would be an easy mistake

to do among those of us that build our own engines and mix and match parts

of several engines........Also those new to the group need to be made aware

that there are subtle differances between the various year model Rotary engines

that we use that are not apparent just by looking........You need to know what

year model your engine is and be certain it is not a bunch of parts cobbled together

by someone.........That is also a problem when buying used parts........Some

sellers on E-bay for instance are not knowledgeable about the Rotary and lump

parts together from all models either on purpose or because they just do not

know any better........IMHO

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Chuck Dunlap" <crayd@cableone.net>: --------------

I just now removed the remaining apex seals from the failed rotor, they both broke in half getting them out. They are the one piece spring style. I can't find any record of the group buy, but they must have been Hurley seals.

The good rotor has two springs, so they must be the Mazdatrix seals. I reported before that the good rotor with the new rotor housing had chatter marks as well, they are not too bad after 150 hours but may not have lasted another 150 hours.

The free height on the one piece spring measured .195" which is within Mazda limits, does anyone know if the limit is different for the one piece spring?

Cary, I normally cruise between 5700 and 6000 RPM, but usually lower if just flying around locally. I don't have a scale that would measure seal weights.

Thanks, everyone for helping sort this out.

Chuck

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Kelly Troyer
Sent: Saturday, March 18, 2006 10:18 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Motor teardown results

Chuck,Tracy and all,

      I also was in the group buy of Hurley Seals in 2002........We had a choice of

Racing seals (two springs) or the so called Long Life seal (one spring).........Do you

recall which you have Chuck ? The Racing seal was more expensive........

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Tracy Crook" <lors01@msn.com>: --------------

One more question Chuck, Were the apex seals you were using single or dual spring type?   This would help identify the original source. Hurley seals use a single spring while Atkins seals use dual springs (stock Mazda type).

Tracy

Subject: [FlyRotary] Motor teardown results

Hi Chuck;

A couple more questions.

Did you typically cruise at 6000rpm for most of the hours? other ranges?
Are the apex seal springs still in spec?
Do you have a gram scale to weight the seals? someone might be able to
identify them that way?

Thanks
Cary