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From: Bob Tilley <btilley@mchsi.com>
Subject: Re: [FlyRotary] Re: Fire extinguishers
Date: Tue, 23 Aug 2005 12:13:18 -0400
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Folks,

I know of another system for a spacecraft where they are concerned of 
the engine having a burn thru. To get protection they wrapped the 
igniter wire/tape around the engine. in the event of burn thru it would 
melt the wire and shut down the engine.  Maybe we could come up with a 
modified "Scaled" system to work inside our cowlings.

Bob

On Aug 23, 2005, at 11:31 AM, Ernest Christley wrote:

> Bulent Aliev wrote:
>
>> I was just thinking: a sensor from a house smoke alarm positioned at 
>> the cooling air exit point, can give a first alert signal? Any smoke 
>> has to come out there.
>> Buly
>
> They're smoke detectors, and the smoke has to reach a certain 
> threshold before the alarm trips.  There won't necessarily be a lot of 
> smoke in a gas fire.  Any smoke that is made will be heavily diluted 
> by the fresh air used for cooling.
>
> There was a recent thread on the Aerolectric list that discussed 
> detection techniques. Infra-red detectors were recommended, and 
> they're supposed to be fairly cheap and will feed into one of those 
> miniature monitors so that you can see what is happening.  In my 
> opinion, it's more weight and complexity than it's worth.
> I didn't like the first idea that was offered; run a twisted pair of 
> thin wire all around the engine compartment.  The theory is that a 
> fire will burn through the insulation, shorting the wires and tripping 
> an alarm.  My theory is that the wires would get oxidized and covered 
> in melted plastic before they could short, preventing a good contact 
> and defeating the alarm.  I would modify the design to be a single 
> wire of the thinnest possible gauge, made from that cheap twisted 
> aluminum stuff instead of real copper.  It would always be powered 
> when the engine was running, and if anything cut the wire for any 
> reason an alarm would go off.  I'd have no idea what cut the wire, but 
> I'd know something was amiss, be it a fire or parts leaving the 
> engine.  Either way the alarm would mean, "Get on the ground. NOW!!"  
> I'm going on the assumption that the death rate on precautionary 
> landings is very low.
> -- 
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