OK Roy. I just want to point out that many people just repeat a public opinion. I am looking for facts that could support this. I know that wooden props need to be beefier due the fact that thin wood simply breaks. But is it really that much of a difference that one could state wooden props are not as efficient? After all the highly praised Hoffmann propellers do have a wooden core. The fiberglass/carbon covering is mainly there to keep away moisture I assume...
Hartmut ----- Original Message ----- From: Roy Stubbs To: Hartmut Beil ; heavensounds ; [email protected] ; Richard Green Sent: Monday, June 09, 2008 9:20 PM Subject: RE: [ercoupe-tech] Props Hi Hartmut: I can only tell you what I have witnessed myself and the advice I have received from presumably qualified individuals that indicate it is not 'myth.' Also, in this instance I do not believe it is an 'apples' and 'oranges' comparison, as the end result is to 'propel' similar aircraft. In my experience of three similar 415-C Ercoupes equipped with C-85 engines and similar spec'ed props at 7148 (I believe) and flying in close formation the one equipped with the wooden propeller could 'not' climb or accelerate with the other two. Indeed, the most experienced pilot was flying with the wooden propeller. We asked my A&P/IA - a former US Navy fighter pilot (from the days of propellers) / Lockheed flight test engineer / and degreed aeronautical engineer and he maintained the difference in wooden vs. metal props. We asked other veteran aviators who had academic / flight test / and formation experience and they all maintained the difference. Indeed, the only person I ever heard disagree with the difference was the wooden propeller salesman - hardly a 'neutral' voice J Roy ------------------------------------------------------------------------------ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Hartmut Beil Sent: Monday, June 09, 2008 2:19 PM To: heavensounds; [email protected]; Richard Green; Roy Stubbs Subject: Re: [ercoupe-tech] Props Importance: Low Roy. I would be interested in proofing this myth about wooden propellers. One has to understand that when comparing wooden props with metal props, it is more like comparing apples with oranges. The wooden props can't be fabricated with such thin blades as the metal prop. This might be a huge disadvantage of the wooden propeller , but maybe not so. I like to see some data comparing the properly chosen props on the same airframe/engine combination. I heard that the metal prop only slightly outperforms the wooden props. The big advantage of a metal prop is the maintenance needed, or the lack thereof. A wooden propeller needs to be checked and taken care of in humid or too dry conditions. Hartmut ----- Original Message ----- From: Roy Stubbs To: heavensounds ; [email protected] ; Richard Green Sent: Monday, June 09, 2008 3:34 AM Subject: RE: [ercoupe-tech] Props Wood props are inefficent compared to simarily spec'd metal props. They noticeably underperform in side-by-side competition all else being equal. Far outweighs any weight advantage. I cannot speak to the exact engineering reasons other than the wooden prop cannot be built to the same tolerances as a metal prop, but I have experienced it first hand in formation flight demonstrations. Roy ---------------------------------------------------------------------------- From: [email protected] on behalf of heavensounds Sent: Sun 6/8/2008 7:36 PM To: [email protected]; Richard Green Subject: Re: [ercoupe-tech] Props For one, the wood prop is lighter. Can carry a bit more fuel or a bit more fat. Eliacim ----- Original Message ----- From: Richard Green To: [email protected] Sent: Sunday, June 08, 2008 4:06 PM Subject: [ercoupe-tech] Props Since I am rebuilding my Coupe's engine over the next few weeks I wanted to overhaul the prop and engine mount as well. Any recommendations for a good shops for those services? Any advantages to wood props besides the appearance piece? By the way, thanks to all for the advice on the control syste. Ujoints made all the difference. Feels like factory new controls now!
