Return-Path: Received: from mail.viclink.com ([66.129.220.6] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2947964 for flyrotary@lancaironline.net; Sun, 25 Jan 2004 09:58:52 -0500 Received: from mail.viclink.com (p170.AS1.viclink.com [66.129.192.170]) by mail.viclink.com (8.11.7/8.11.7) with ESMTP id i0PEwmL62850 for ; Sun, 25 Jan 2004 06:58:49 -0800 (PST) Message-ID: <4013D98E.6080604@mail.viclink.com> Date: Sun, 25 Jan 2004 06:58:22 -0800 From: Perry Mick User-Agent: Mozilla/5.0 (Windows; U; Win95; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Torsionals References: Content-Type: multipart/alternative; boundary="------------010505020406040200000409" X-RAVMilter-Version: 8.4.3(snapshot 20030217) (mail.viclink.com) --------------010505020406040200000409 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit > > > > > Tracy Crook wrote: > >> Don't know if anyone has commented on this already Pete, but yes, >> the single rotor does have torque reversals. >> >> Don't know how much of a problem this will be but the torque >> signature (IGNORE RPM FOR THIS COMPARISON, it doesn't matter) >> will be the same as the three cylinder piston engine. Raven had >> a challenging time developing a redrive for the Suzi/Geo 3 cyl. >> engine if that is any clue. >> >> Tracy > > If the two rotor is similar to a 4 cylinder 4 stroke piston > engine, wouldn't a one rotor be similar to a 2 cylinder 4 stroke > engine? Lamar has published the plots many times showing no torque > reversals for a two rotor but very strong torque reversals for a > one rotor. > >-- >Perry > > > Ahh yes, the never ending debate on how to compare the rotary with > a piston engine. > > The reason I said to ignore the rpm when comparing torque > signatures was to compare ONLY the relative torque amplitude > variation of the engines. The two rotor engine looks just like a > 6 cylinder in this respect. Yes, I know the 2 rotor rotary only > has two power strokes per rev but they are 50% longer (270 degrees > vs 180) than those of a piston engine, thus, they overlap exactly > like those of a 6 cyl. This is relavant because tortional > resonance has nothing to do with rpm that the system happens to be > turning. > > The torque variation represents the amount of excitation energy > fed into the system. The higher this energy, the more critical > the damper is if the system has to spend any time at or near the > resonant point. In terms of this excitation energy, the one > rotor probably has double or more the amount that a 2 rotor has > (all else being equal). Notice that this excitation energy is not > directly related to engine horsepower. > > Somehow I doubt that I have made things any clearer. > > Tracy > Yes it does make it clearer, thanks. I thought about that after I posted the last message (maybe I just reread your previous message!). It is clear that the PSRU will be under more "stress" with a one-rotor. Has anyone ever bolted your PSRU to a one-rotor? Do you even approve it for a one-rotor? -- Perry --------------010505020406040200000409 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit

Tracy Crook wrote:

Don't know if anyone has commented on this already Pete, but yes, the single rotor does have torque reversals.

Don't know how much of a problem this will be but the torque signature (IGNORE RPM FOR THIS COMPARISON, it doesn't matter) will be the same as the three cylinder piston engine. Raven had a challenging time developing a redrive for the Suzi/Geo 3 cyl. engine if that is any clue.

Tracy

If the two rotor is similar to a 4 cylinder 4 stroke piston engine, wouldn't a one rotor be similar to a 2 cylinder 4 stroke engine? Lamar has published the plots many times showing no torque reversals for a two rotor but very strong torque reversals for a one rotor.
-- 
Perry
Ahh yes, the never ending debate on how to compare the rotary with a piston engine.

The reason I said to ignore the rpm when comparing torque signatures was to compare ONLY the relative torque amplitude variation of the engines. The two rotor engine looks just like a 6 cylinder in this respect. Yes, I know the 2 rotor rotary only has two power strokes per rev but they are 50% longer (270 degrees vs 180) than those of a piston engine, thus, they overlap exactly like those of a 6 cyl. This is relavant because tortional resonance has nothing to do with rpm that the system happens to be turning.

The torque variation represents the amount of excitation energy fed into the system. The higher this energy, the more critical the damper is if the system has to spend any time at or near the resonant point. In terms of this excitation energy, the one rotor probably has double or more the amount that a 2 rotor has (all else being equal). Notice that this excitation energy is not directly related to engine horsepower.

Somehow I doubt that I have made things any clearer.

Tracy

Yes it does make it clearer, thanks. I thought about that after I posted the last message (maybe I just reread your previous message!). It is clear that the PSRU will be under more "stress" with a one-rotor. Has anyone ever bolted your PSRU to a one-rotor? Do you even approve it for a one-rotor?

-- 
Perry

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