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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2376182@logan.com>
Subject: Re: [FlyRotary] Re: Hose clamp myth busters
Date: Tue, 9 Oct 2007 09:45:02 +1000
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 Ed,
Agreed - I was just thinking about the new batteries myself and was 
wondering what sort of flight time you might get out of a set for DC 
115 -125HP electric engine.
After seeing Bill's Video, they certainly have the power!
Perhaps Bill can give us some weights and life expectancy?
Not that I think it practical, but it terms interest and the 'Wow' factor of 
an experimental aircraft.
George (down under)

> Good point, George.
>
> I certainly am guilty of over engineering things.  That is the major 
> reason my aircraft empty weight was originally 1170 lbs which is about 120 
> lbs heavier than the average RV-6A.  My motto was (is?) if in doubt, make 
> it stout!!  So an oz here and an oz there and soon it added up to 120 lbs 
> more than I would have liked.
>
> Fortunately 44 lbs of that was due to two batteries which I initially 
> though absolute essential but after 6 years of flying and hauling around 
> that extra 22 lbs and never using it except to help start on a cold 
> morning, I now fly with one 14 lb battery.  But, it took six years of 
> experience before I could give up that extra battery.  Now, If I could get 
> one of Bill Dube's new 3.5 lbs batteries for less than my annual income 
> (joke! Bill), I would put another battery back in.
>
> But, as has been mentioned and inferred, if you don't feel comfortable 
> with a certain approach then you will find some justification for using a 
> different approach.  Like fuse vs circuit breaker - both certainly do the 
> job they were intended to do, but I just can not bring myself to using a 
> fuse for a flight critical system.  I do use them for secondary systems. 
> Don't want to start that war again, but just using it as an example.
>
> Ed
> ----- Original Message ----- 
> From: "George Lendich" <lendich@optusnet.com.au>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Monday, October 08, 2007 6:26 PM
> Subject: [FlyRotary] Re: Hose clamp myth busters
>
>
>>>> Time and time again, experienced people place themselves in situations 
>>>> where another second or two of engine power, is the difference between 
>>>> an interesting story, and a heart wrenching tragedy. Last fall two 
>>>> pilots, in a  borrowed Bonanza, hit the edge of a ditch off the end of 
>>>> a long runway. No  engine power left to manage. Another 12 inches of 
>>>> altitude. Another second  of power and they could have been explaining 
>>>> this story to the FAA or plane  owner, or others at the next meeting. 
>>>> They lived for weeks with terrible  injuries, and both died leaving 
>>>> behind astounding medical bills and shattered  families. Spring clamps 
>>>> are acceptable on vacuum hoses to power some back up  gages.
>>> I love the depth of information and experience you bring to this list, 
>>> Lynn;  but, unless you can point to a spring clamp being the cause of 
>>> the mentioned accident, I'd say that it is completely irrelevant to this 
>>> discussion.  Mechanical failures happen, and often they could be delayed 
>>> or avoided altogether if one part was just slightly stronger.  But 
>>> there's a long row to hoe to move from that statement to spring clamps 
>>> only being acceptable for backup vacuum gauges.
>>>
>>> We don't have solid data, so we fall back to what feels good, but there 
>>> is some unintended hypocrisy going on here.  If the spring clamps aren't 
>>> up to the job, why would they be acceptable on back-up gauges?  Those 
>>> gauges are going to be the primary gauges after the primaries fail, and 
>>> if the clamp failed it will kill ALL of them anyway.  Why does it feel 
>>> acceptable to use the clamps on the backups, but not the primaries?  And 
>>> why are the spring clamps found all over the cooling system of some of 
>>> the most reliable passenger vehicles ever mass produced?  I doubt 
>>> Toyota, Honda, Ford, Dodge, or BMW use the feel good metric when 
>>> specifying their clamps.
>>>
>>> I'm not really ranting about hose clamps as much as the feel good 
>>> mentality . . . the dismissal of a solution without a quantification of 
>>> what it's supposed to do.  I'm using little velcro straps to contain my 
>>> wire bundles.  These things are amazing for a tube frame airplane. 
>>> They're cheap, convenient, quick to install or move, allow some play in 
>>> the wire while holding it securely and provide for non-abrasive 
>>> separation from the structural tubes.  "But it's just velcro," a friend 
>>> complained. So I strapped a wire to a shelving support tube, and let him 
>>> hang from it. He gave up when the wire was cutting into his hands 
>>> instead of coming loose.
>>>
>>> The aviation industry is rife with over-engineering because someone 
>>> needed an extra ten feet to make the runway.  It's my belief that it 
>>> does nothing but drive the price up.  I say 'belief' because I have no 
>>> actual data to back up the belief.  Until there's some data showing how 
>>> spring clamps will fail in a typical cooling system, I'm going to have 
>>> to reject that notion.  There's just way to much evidence showing that 
>>> they do work...reliably...for years on end.
>>>
>>> That being said, I'll actually use worm clamps.  There's less worry 
>>> about having the exact right size for every hose, simplifying my 
>>> inventory management.
>>
>> Ernest,
>> I agree with your statement we tend to overengineer everything, I believe 
>> through ignorance and I don't think that's too critical of myself and 
>> others, but before we challenge those more experienced, I think some 
>> experimentation should be involved.
>> It's your idea, so what about testing these spring clams to pressure (and 
>> over) and over extended time to see what the outcomes really are!?
>> George ( down under)
>>
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