Received-SPF: pass
 receiver=logan.com; client-ip=209.86.89.68; envelope-from=jerryhey@earthlink.net
DomainKey-Signature: a=rsa-sha1; q=dns; c=simple;
  s=test1; d=earthlink.net;
  h=Date:Subject:Content-Type:Mime-Version:From:To:Content-Transfer-Encoding:In-Reply-To:Message-Id:X-Mailer;
  b=sLm7ILUcWNihFGSGk15N4UyH/d/JU+Kvz6J+pKdVfTvPGTB02wIHe8P0KwyrqtSd;
Date: Tue, 12 Apr 2005 18:36:42 -0500
Subject: Re: [FlyRotary] Re: Ram and Alt air
Content-Type: text/plain; charset=US-ASCII; format=flowed
Mime-Version: 1.0 (Apple Message framework v552)
From: Jerry Hey <jerryhey@earthlink.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Content-Transfer-Encoding: 7bit
In-Reply-To: <list-866946@logan.com>
Message-Id: <B95DDD7E-ABAB-11D9-A355-0003931B0C7A@earthlink.net>

I have not actually studied the ideal ram scoop opening. I know that 
Tracy is using a 3inch dia round  scoop that would have about 7 inches 
of area, just a little smaller than the scoop I proposed.  I want to 
keep the scoop as low as possible while retaining the performance.  The 
snouts that stick up into the air are not the look I want.  Does the 
scoop get smaller with a higher top end?  What would it be for 240 mph? 
    Jerry


On Tuesday, April 12, 2005, at 06:19 PM, Al Gietzen wrote:

>
> Here is pic of the plenum (at this point a piece of 1/4 inch ply.  The
> ram air scoop will be 4 inches wide and  two inches high.
>
> Jerry:
>
> Is the 2" x 4" the opening size?  I think that is more than double the 
> area
> that would give the amount of ram air needed for a 2-rotor at, say, 
> 120 kts.
> So it will be spilling air and likely cause some amount of unwanted 
> drag.
> Ideally, a ram induction scoop is close to the area needed for near top
> speed; and have radius on the entrance lip (about that of your index 
> finger)
> to minimize entrance loss when you are at low speed.
>
> FWIW, I have no idea it any of this matters for what you're doing.
>
> Al
>
>
>>>  Homepage:  http://www.flyrotary.com/
>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>