X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-04.southeast.rr.com ([24.25.9.103] verified) by logan.com (CommuniGate Pro SMTP 5.1c.3) with ESMTP id 1376979 for flyrotary@lancaironline.net; Tue, 12 Sep 2006 09:21:50 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-111-055.carolina.res.rr.com [24.74.111.55]) by ms-smtp-04.southeast.rr.com (8.13.6/8.13.6) with SMTP id k8CDKeZ5028461 for ; Tue, 12 Sep 2006 09:20:49 -0400 (EDT) Message-ID: <000101c6d66f$041c3830$2502a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: It runs! Date: Mon, 11 Sep 2006 23:44:29 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Virus-Scanned: Symantec AntiVirus Scan Engine ----- Original Message ----- From: "Ernest Christley" To: "Rotary motors in aircraft" Sent: Monday, September 11, 2006 10:48 PM Subject: [FlyRotary] Re: It runs! > Ed Anderson wrote: >> >> ----- Original Message ----- From: "Ernest Christley" >> >> To: "Rotary motors in aircraft" >> Sent: Monday, September 11, 2006 9:02 AM >> Subject: [FlyRotary] Re: It runs! >> >> >>> Al Gietzen wrote: >>> >>>> I'd say get a prop load on there, and adjust mixture, get some readout >>>> of >>>> what's going on. I don't think you necessarily want the thing spinning >>>> over >>>> 6000 on first startup anyway. >>>> >>> >>> Way ta' go, Bob. Several people have given the advice to put a load on >>> the engine, but if you're buying parts as you progress (like me) you may >>> not have a prop yet. A 4ft section of wooden fence post will make a >>> nice, disposable load though. >>> >> >> Good idea, Ernest. However, without an airfoil cut into the fence post, >> its not going to impose much load - some resistance for sure, as it spins >> through the air, some additional inertia - but little load - compared to >> a prop. >> >> Ed >> >> > I took a while to respond, because at one time I had and email that laid > out some equations for calculating the amount of power that a square > piece of wood would absorb at different RPM. Some French guy had worked > it out. The idea was that you would guess at what power you thought you'd > get, make up a 'fence post' and run it. Use the results to get a better > idea of what the real Hp is and cut another 'fence post'. I've since > changed computers and I haven't been able to find that nugget. > > As for throwing a chunk of fencepost as some else alluded to, as long as > treated wood is avoided and some effort is expended not to select from the > seconds bin, any wood that a fence post is likely to be made from will be > more than strong enough for a propeller. > If you find the equation, I'd like to see it. A 4" square piece of timber is more than I would care to have swinging at 2400 rpm in front of me {:>). Ed