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From: "George Lendich" <lendich@aanet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-4184387@logan.com>
Subject: Re: [FlyRotary] tuned intake  [FlyRotary] Re: P-Port performance
Date: Wed, 31 Mar 2010 17:46:26 +1000
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 Ed,
No wonder I couldn't work it out.
Does anyone we know have that Dynomation program.
I wonder how much it costs.
George (down under)

>A "tuned" intake covers a wide Varity of techniques ranging for Hermholtz,
> RAM, Dynamic Intake, Inertia, etc,.  There are basically three 
> conceptually
> different approaches although they tend to merge under certain conditions.
> You have the resonant tuning, the pulse tuning and the inertia turning
> concepts.  However, truth be known all three phenomena occur in most 
> intake
> systems - it's a matter of emphasis.
>
> The thing that really complicates it is the fact that within any induction
> or exhaust system you have Finite Amplitude Waves - the power of these 
> pulse
> makes a 135 db sound wave very puny - these pulses can actually pound 
> metal
> apart.  They do not interact linearly as do "sound waves" - in fact they 
> can
> respond in what at first seems to be weird ways.  For instance they may
> reverse there "polarity" depending on whether they encounter an open or
> closed termination.
>
> It has only been with the advent of digital computers has it been 
> practical
> to even try and model the effects of these waves in an induction system. 
> I
> find them fascinating.
>
> Here are a few references that some of you might find interesting.
>
> http://home.earthlink.net/~redcat/pulse_ram/theory.html
>
> http://www.motionsoftware.com/simtech.htm
>
> http://www.proracingsim.com/dynomationmainpage.htm
>
> http://www.audietech.com/DMfeaturetable.htm
>
>
>
>
> Ed Anderson
>
> Rv-6A N494BW Rotary Powered
>
> Matthews, NC
>
> eanderson@carolina.rr.com
>
> http://www.andersonee.com
>
> http://www.dmack.net/mazda/index.html
>
> http://www.flyrotary.com/
>
> http://members.cox.net/rogersda/rotary/configs.htm#N494BW
>
> http://www.rotaryaviation.com/Rotorhead%20Truth.htm
>
> -----Original Message-----
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
> Behalf Of George Lendich
> Sent: Tuesday, March 30, 2010 6:22 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: P-Port performance
>
> Thanks Bill,
> I'm transposing off a larger document which was done piecemeal over a 
> period
>
> of time, for my own benefit and you picked me up on some transference
> typo's. I've amended the attached copy.
>
> Your right it's saying how much air you need and how fast that air will 
> get
> there (speed now included). Perhaps I shouldn't have labeled it Tuned. The
> rule of thumb has been between 18 -21" for tuned manifold length ( from 
> what
>
> I understand) and this supports that theory.  How  much the reflected wave
> affects the speed is still beyond me, at this point in time, however it 
> you
> think of the variables as Tracy suggested your going to get confused, I 
> know
>
> I do. This approach just gives a rough start point - it works for me 
> however
>
> I do find the outcomes interesting, when you do some comparisons on
> variables.
> George (down under)
>
>
>> George,
>> Why is the Renesis horsepower lower than the standard at 7500 and higher
>> than the standard at 7200?  It also is higher at the lower rpm??
>>
>> Regards the tuned length.  I thought the idea was to get a reflected wave
>> to
>> bounce from one inlet to the other just as it was closing.  If I
>> understand
>> what you have said, your calculation is how long a tube it would require
>> to
>> hold one charge of air??
>>
>> Bill B
>>
>> -----Original Message-----
>> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
>> Behalf Of George Lendich
>> Sent: Tuesday, March 30, 2010 1:10 AM
>> To: Rotary motors in aircraft
>> Subject: [FlyRotary] Re: P-Port performance
>>
>>
>> Cary,
>> Ed came to the rescue (once again) and reminded me that was a conversion
>> of
>> inlet speed of 120.58 mph to seconds a minute. I adjusted the attached
>> info
>> sheet, to reflect this information).
>>
>> The maths isn't a problem, however Ed has a knack of knowing how to
>> approach
>> and work through a problem, whereas most of us wouldn't bother. This must
>> be
>> how the engineers do it to get to a start point.
>>
>> I don't know of anyone needing to go to 8,000 rpm and if they did they
>> might
>> need another ratio reduction drive, in that case they might need a
>> slightly
>> larger inlet. However greater VE would need to be driven by a greater
>> inlet
>> velocity and a bigger inlet has a reduced velocity, but I'm sure 120% VE
>> is
>> achievable in the racing game and much higher rpm, much as I would love 
>> to
>> see it at our rpm. Then again I would love to be proven wrong.  Perhaps
>> with
>> the higher peak inlet speed Tracy indicated was available. We won't know
>> until we get mare data, perhaps from bill, down the track.
>>
>> Knowing how you love to dabble in things, ( nothing wrong with that) I
>> included a calculation for inlet tube length, in this latest attachment -
>> mind you their only ball park figures, but to me it gives a rough start
>> point and an understanding of the processes involved.
>> Hope that helps.
>> I do have some figures on exhaust speed if your interested.
>> George (down under)
>>
>>> Hi George;
>>>
>>> What is the meaning / origin of the value "176.85" in your "Diameter
>>> of Inlet" calculation?
>>> You should also try running your calculation with 8000rpm and 120%VE.
>>>
>>> SAE900032 has a bunch of useful intake and exhaust info including
>>> volumetric efficiency charts versus Pport sizes and intake lengths.
>>> There are other useful SAE papers that Paul posts on the other list
>>> periodically.
>>>
>>> Cheers
>>
>>
>> --
>> Homepage:  http://www.flyrotary.com/
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>>
>
>
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