🚀 go-pugleaf

ahennell [Thu, 23 Jan 2003 01:21:51 GMT] wrote:

>Marco Desloovere wrote:
>
>> ahennell [Wed, 22 Jan 2003 01:48:59 GMT] wrote:
>>
>> >Marco Desloovere wrote:
>> >
>> >> I was wondering whether it would be possible to blow out the Canberra
>> >> fires using helicopters? Just like one would blow out the flame of a
>> >> candle...
>> >
>> >- Energy required to "blow" out a fire would be phenominal.
>>
>> How much is "phenomenal"?
>> More than a couple of your most powerful helicopters?
>> If it cannot be calculated, then it's obviously a trial and error
>> thing.
>
>Have you ever stood between a bushfire and a house?  Have you ever 'felt' the
>beast as it approaches?  At 50m, the heat is unbearable.  The energy of a
>fire is far beyond what a helio could hope to overcome.

I have witnessed 2 big adjacent stores burn down to the ground. One
was selling carpets and the other all sorts of electrical appliances,
from electric razor to washing machine.
It was awesome! I was standing about 100 m away from the fire and it
felt as though the hot midday summer sun was shining in my face.

>> The point is that if my method were applied *before* the fire gets out
>> of hand, then no phenomenal force would be required later.
>>
>> I think that it might be worth a try!
>
>In the wilderness?  You wouldn't get close enough for all the trees - the
>only effect would be to fan the fire & spread embers.

Yes, the embers would be a problem.

>> >- Smoke usually travels with the fire - in the direction you'd have the
>> >choppers approaching from - stopping any visability
>>
>> This could be co-ordinated from the ground using adequate electronic
>> devices, if really necessary.
>>
>> >- Formation flying that close to eachother, and that close the ground is
>> >never a good idea at the best of times (SAS & Blackhawk?)
>>
>> Indeed, and it would require some excellent pilots and also good
>> co-ordination from the ground!
>
>Fire creates its own weather - updrafts, fire tornados, winds - it's hard
>enough flying through when you're a sole aircraft at height, let alone
>getting close enough to trees, powerlines, houses, etc to 'blow' anything
>onto the fire.

OK, point taken.

>> >- Wouldn't produce enough 'wind' to make much effect
>>
>> That remains to be seen. Big choppers can create quite a big thrust!
>
>They don't 'blow' air, they rotate their wings through it.  yes, there's
>significant downdraft from them, but it's not like a fan sitting in the air.

I have seen hovering helicopters flatten a rough sea. This is pretty
impressive.

>> >- You'd end up, if anything, spreading fire more than putting it out
>>
>> That is a possibility which could only be observed, if the operation
>> were tested in real life.
>
>Have you watched wind gusts & their effects on fires?

Random wind gusts yes, but what about a *controlled* constant gust of
wind?

>> >- Heat of the ground will simply reignite anything you do manage to blow
>> >out
>>
>> That heat would be much easier to control than a raging fire!
>
>A bucket drop works because the initial gust of cold air & water quenches the
>fire, and the remaining water helps stop reignition.  Air alone would have a
>very difficult time in stopping that reignition.
>
>I have personally seen fires put out, only to watch leaves fall to the ground
>& spontaneously ignite.  You are underestimating the heat component.

Well, perhaps the helicopter has to hover over the fire long enough?

"Long enough" will have to be determined through experimental trial
runs.

>> >- The energy of a moving fire front is simply massive.  These fires give
>> >off the equivalent force of many hiroshima bombs during their burn.
>>
>> Yes, indeed. That is why my method should have to be used as quickly
>> as possible, to avoid the beginning of real massive fire.
>
>Again, where these fires start there is no way of getting a chopper that
>close to do any effect.  Let alone any ground controll.

OK, I realize that a raging bush fire, that has gotten out of hand,
would be a challenge...!

>> >Nup, I can't see it working.
>>
>> It may have to be tried on a small scale first, to see whether it
>> *really* doesn't work...
>
>Well, off you go.  This isn't putting iron wheels on a car & sending it along
>tracks, it's something that, when you consider all the components of the
>operation, would simply not work.
>
>May I ask:  Are you a firefighter? A pilot?  Have an understanding of fire
>behaviour or flight theory?

No, I am not a fire-fighter nor a pilot, but that is not the point.

I think it would be interesting to observe, in a live experiment, of
what is happening *exactly*, when a couple of helicopters try to blow
out a fire using the downdraft from their rotating blades.

It might turn a crazy idea into a crazy experiment, but what if it
turns out to be a crazy *solution*...?

Marco