From: "Charlie England ceengland7@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: over square and detonation of a rotary for my
 pilot friend
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-542416@logan.com>
Message-ID: <8b6ed470-ea7e-5ed2-e13f-cf49606b8b5a@gmail.com>
Date: Sat, 18 Jul 2020 10:23:15 -0500
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All,

Operating 'oversquare' in the piston a/c world is normally interpreted 
as MAP (in inches of water) being larger than engine rpm divided by 100. 
Ex: 28" MAP & 2200-2400 rpm during takeoff and climb is oversquare, and 
would be a normal occurrence with a fixed pitch Lycoming operating from 
an airport near sealevel. And virtually all turbocharged a/c engines are 
*always* operating oversquare to some degree. So the hazard of  
'oversquare', in and of itself, is largely an 'old hangar tale'. What 
Lynn said is the limiting factor in piston engines, just like the rotary.

Not sure how you'd apply the metric to a rotary anyway, since its higher 
rpm would mean it is almost never in the 'oversquare' area.
Charlie
https://www.avweb.com/features_old/why-over-square-is-good/

https://www.aopa.org/news-and-media/all-news/2018/october/pilot/savvy-aviator-hip-to-be-over-square

On 7/18/2020 9:08 AM, Stephen Izett stephen.izett@gmail.com wrote:
> Thanks Bobby.
> We are just NA, but the idea of a turbo and 250hp is appealing and would make the Glasair hum along at altitude!
>
> Steve I
>
>> On 18 Jul 2020, at 9:17 pm, Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net> wrote:
>>
>> Hi Steve,
>> Are you running a turbo? I didn't see it listed when you asked about oversquare, so I thought you were running NA.
>>
>> Sent from BlueMail
>> On Jul 18, 2020, at 7:34 AM, "Bobby J. Hughes bhughes@qnsi.net" <flyrotary@lancaironline.net> wrote:
>> Steve,
>>
>> I used 6800-7000 rpm, 36-38” MP with F/A in the 12’s for takeoff.  Around pattern altitude I would reduce to 6000 rpm and 30-32” MP with F/A a little richer than best power in the 13’s. I monitored EGT’s during all phases of flight and would make mixture changes as needed to keep EGT around 1600 or less during high power operations. I used a vernier cable to control the super charger bypass and could dial in the desired MP. For the turbo I was planning a 4# waste gate with an air control valve to apply more pressure to the top of spring at higher altitudes or lower rpm. Still using the same target numbers as with the super charger. But no turbo for the S21 project. I guess I need to sell it at some point.
>>
>> So I only used boost for takeoff and for normalization most of the time. I liked operating  28- 30” with the prop between 1700-2000 rpm. Rich or lean to keep the EGT under 1600F and intake temps under 140F.
>>
>> Bobby
>>
>> Sent from my iPad
>>
>>> On Jul 17, 2020, at 9:53 PM, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
>>>
>>> ﻿Thanks Bobby.
>>> What boost are you running?
>>>
>>> And I meant to ask, my friend is asking what power setting we consider the engine to be OK with for continual operation?
>>>
>>> Steve Izett
>>>
>>>> On 18 Jul 2020, at 9:59 am, Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:
>>>>
>>>> My preferred cruise economy settings 30” MP, 4800-5200 rpm. F/A 15:8 lean. Or 30-34” MP, 5200-5400 rpm F/A 14:0 or whatever was need to keep EGT below 1600F and intake air temp below 140F.
>>>>
>>>> Bobby
>>>>
>>>> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
>>>> Sent: Friday, July 17, 2020 7:10 PM
>>>> To: Rotary motors in aircraft
>>>> Subject: [FlyRotary] over square and detonation of a rotary for my pilot friend
>>>>
>>>> Hi people.
>>>>
>>>> My test pilot friend and I are continuing our journey of extending the phase#1 envelope and now experimenting with engine settings.
>>>> With a flight adjustable prop he is asking questions about 'over square' and detonation.
>>>> Can anyone give me an answer for him?
>>>>
>>>> Thanks
>>>>
>>>> Steve Izett
>>>> Glasaie Super IIRG Renesis 4 port RD1C variable pitch prop.
>>>>
>>>>
>>>>
>>>>
>>>>
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