The man who made the statement is highly convinced of his knowledge, but I
have noted that he is sometimes wrong.
-----Original Message-----
From: Jim Nichols
Sent: Saturday, July 28, 2012 6:15 PM
To: Olympus Camera Discussion
Subject: Re: [OM] Fly-in airplane photo of the day
Hi Bill,
No PhD here, but I could consult my son who does have it. Your friend may
be correct with the aircraft at rest. However, when one adds a forward
speed vector, things change.
For th AT-6:
Prop diameter is normally 109 inches
Max power is rated at 2250 rpm
This should result in a radial tip speed of 1068 feet/second
The speed of sound in air at sea level and standard temperature is 1126
feet/second.
It doesn't take much of a forward speed vector to bring the effective tip
speed to the speed of sound, since it is already at Mach 0.95 based on the
radial tip speed.
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Bill Pearce" <billcpearce@xxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Saturday, July 28, 2012 4:00 PM
Subject: Re: [OM] Fly-in airplane photo of the day
>I have a friend, an aerodynamicist with a PhD, who states clearly that no
> prop tip ever goes supersonic, as that would make it unable to perform its
> task. I'm not so sure I believe him, though. There's very l little else
> that
> would account for that noise. Once heard, never forgotten.
> -----Original Message-----
> From: Chris Barker
> Sent: Saturday, July 28, 2012 1:42 PM
> To: Olympus Camera Discussion
> Subject: Re: [OM] Fly-in airplane photo of the day
>
> Perhaps because it has a small prop whose tips go supersonic, Bill? If it
> has a prop with a small area, perhaps it has to go faster to create
> sufficient thrust.
>
> I'll ask someone who might know, at work.
>
> Chris
>
>
> On 28 Jul 2012, at 19:00, "Bill Pearce" <billcpearce@xxxxxxx> wrote:
>
>> I love the sound of round engines turning props, but really, the T-6? How
>> could anything with such low performance make so much noise? The most
>> recent
>> T-6, however, just makes a slight wooosh.
>>
>> -----Original Message-----
>> From: Jim Nichols
>> Sent: Saturday, July 28, 2012 12:04 PM
>> To: Olympus Camera Discussion
>> Subject: Re: [OM] Fly-in airplane photo of the day
>>
>> 600 hp Pratt & Whitney, combined with a prop that was maximized for
>> noise.
>> ;~)
>>
>
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