From: "Charlie England" <flyrotary@lancaironline.net>
Received-SPF: pass
 receiver=logan.com; client-ip=209.85.220.41; envelope-from=ceengland7@gmail.com
Subject: Re: [FlyRotary] Prop
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-8003168@logan.com>
Message-ID: <55FF5FCA.7000907@gmail.com>
Date: Sun, 20 Sep 2015 20:39:22 -0500
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101
 Thunderbird/38.2.0
MIME-Version: 1.0
In-Reply-To: <list-8003168@logan.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit

On 9/20/2015 11:56 AM, GEORGE PUTNAM wrote:
> Ernest made it impossible for me to pass up his nearly completed Dyke Delta. So basically I am just starting in the rotary world. For now I am figuring out Megasquirt and   Asking the group to opine on a prop. Looking forward to responses. The Dyke made a 4500 mile road trip to get to my hanger.
> George

Hi George; welcome to the group.

If memory serves, Ernest's redrive wasn't one of Tracy's. Do you know 
the ratio? You'll need to tell the prop carver the expected cruise & top 
speeds (honest, non-optimistic numbers), the actual HP of the engine 
(again, honest #), max expected rpm *of the prop* at top speed (wide 
open, low altitude), and the maximum diameter prop that the plane can 
physically handle safely with adequate ground clearance. (With a fixed 
pitch prop, you want the largest diameter you can safely swing without 
the tips approaching Mach, to improve takeoff/climb performance). The 
prop pitch number should be whatever the prop carver says it should be, 
because different prop makers use different methods to measure pitch.

Charlie