REFLECTOR: [Fwd: [FlyRotary] UV-Tron Fire Detection System]

Jim Sower canarder at frontiernet.net
Tue Aug 30 23:59:22 CDT 2005


Doesn't UV penetrate smoke?  I would guess you'd have a tough time 
generating enough unpurged smoke to cause a problem. 

Interesting concept though.  I always thought fire fighting stuff on a 
plastic airplane was kind of silly.  Most detection systems would seem 
to give a lot more false positives than anything else and a LOT more 
folks would die in too hurried emergency landings in challenging terrain 
than would ever be saved by detecting a fire soon enough to get on the 
ground successfully and while the plane was still flyable.  Sort of like 
the military banned practice flameout approaches when they discovered 
that many more people were getting killed practicing than were being 
saved by the benefits of practice. 

Once on fire, a plastic airplane doesn't last long.  Couple of minutes 
for wing root (that's all your roll and yaw resources) and then the spar 
goes shortly thereafter.  It would seem that if you're at cruise 
altitude, the only thing fire detection buys you is the opportunity to 
die all tensed up.  Prevention appears to be the only approach that will 
yield real world dividends. 

Now this UV detector has me revisiting all that.  The biggest danger is 
still false positives though.  You still have to land very quickly and 
successfully, and acquiring the skill to do that will most likely cost a 
lot of lives and airplanes.  Got to wonder if it's worth it, all things 
considered.  Hard to figger - we don't have any idea of the cost, and 
perhaps less of the benefits.

I'll have to focus on prevention for now ... Jim S.


Scott Derrick wrote:

> I wonder how it would do if there was a lot of smoke?
>
> Scott
>
> Jim Sower wrote:
>
>> Thought this might be of interest ...
>>
>> -------- Original Message --------
>> Subject:     [FlyRotary] UV-Tron Fire Detection System
>> Date:     Tue, 30 Aug 2005 08:04:25 -0500
>> From:     Mark R Steitle <mark.steitle at austin.utexas.edu>
>> Reply-To:     Rotary motors in aircraft <flyrotary at lancaironline.net>
>> To:     Rotary motors in aircraft <flyrotary at lancaironline.net>
>>
>>
>>
>> Last week we were discussing various methods of dealing with fire 
>> dangers in our aircraft. I decided to try out the Hamamatsu UV Tron 
>> flame sensor, and promised to report my findings to the Fly Rotary 
>> group.
>>
>> I located a pre-assembled circuit board from Superdroid Robots, a 
>> company that supplies a variety of parts for robots. They were the 
>> only place I could find that carried the Hamamatsu C3704 flame 
>> detector and driver card. So, I ordered both along with a relay 
>> board. (Attached is a picture of the boards.) The UV Tron sensor is 
>> the clear glass “bulb” in the foreground. The small board on the left 
>> is a voltage converter, allowing it to be connected directly to 14v.
>>
>> I hooked it up to a 12v cordless drill battery and tested it using a 
>> propane fire starter. It could easily “see” a flame from 6’ away 
>> (maybe more, but I didn’t test it beyond 6’) and up to 90* right or 
>> left. I didn’t test up/down, but the spec sheet indicates that it is 
>> about the same in the vertical and horizontal planes. I could not get 
>> it to false trip by using a fluorescent or a halogen light. There is 
>> about a .5 second delay before it trips the relay. The tech rep at 
>> Superdroid Robots indicated that the UV Tron sensor could be remotely 
>> mounted up to 3’ away from the board. I plan on mounting it in a 
>> small box on the firewall with the leads running though the firewall 
>> to the circuit boards inside the cabin, wired to a big red flashing 
>> LED on the panel. Everything in the picture (including s&h) ran $150. 
>> I look at it as cheap insurance. Hopefully, I will never need it.
>>
>> Mark S.
>>
>>
>> ------------------------------------------------------------------------
>>
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>>
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