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From: daver@felix.UUCP (Dave Richards)
Newsgroups: net.aviation
Subject: Re: Airport Fog
Message-ID: <962@felix.UUCP>
Date: Thu, 13-Mar-86 20:57:23 EST
Article-I.D.: felix.962
Posted: Thu Mar 13 20:57:23 1986
Date-Received: Sat, 15-Mar-86 19:25:29 EST
References: <491@ssc-bee.UUCP>
Reply-To: daver@felix.UUCP (Dave Richards)
Distribution: net
Organization: FileNet Corp., Costa Mesa, CA
Lines: 68

In article <491@ssc-bee.UUCP> maa@ssc-bee.UUCP (Mark A Allyn) writes:
> Operation FIDO consisted of employing several large 
>gasoline burners placed alongside the runways of airports. hat were used
>to raise the fog cieling by heating the air in the vicinity of the
>runway and causing circulation.
>
>My proposal would be to construct deflectors at periodic intervals
>along the parimeter of the runway sections of airports; deflectors
>similar to those used to protect roads and hanger areas from jet 
>blast. In the event of fog, a number of aircraft, preferably jets,
>whose exhaust is hot, would back up to the deflectors and run their
>engines, thereby hopefully causing the same effect as that accomplished
>by Operation FIDO.
>
>Mark A. Allyn

I think Mark's heart is in the right place and he has a good idea, but I
think it needs a little massaging to get the maximum benefit.

1. While jet engines do produce large amounts of heat, they are primarily
designed to produce large quantities of thrust.  
To use a jet engine burning jet aviation fuel as
a heater is pretty expensive.  Especially when the engine is attached to
an aircraft with a value in the 100 million dollar range. That's a lot
of fuel, and a lot of real estate sitting around depreciating.

2. Jet engines are noisy.  A few of them sitting around idling is one thing,
but if we're talking about several running for long periods at high power
settings, then we're talking about people complaining (and rightfully so!)
if they live within about a mile or two of the airport.

3. How would the aircraft be tethered to prevent it from racing around,
terrorizing the neighborhood?  Remember, we're looking at somewhere
between 10,000 and 100,000 pounds of thrust for most of these aircraft.
I don't know how long brakes will be reliable at these loads.  A pilot 
would probably be required in each cockpit at all times, just in case.
(or at least someone able to steer the plane, shut down the engines, etc.)
Those wages add up to more expense.

4. I question the usefulness of clearing the fog *right at the runway*.
While this might help planes taxi, what good does it do right after
takeoff or on final approach?  Isn't that where the most vision is needed?
Of course if there's wind, and it's going right down the runway then
you'd have sort of an "alley" of vision stretching out the final path.
Any wind other than straight down the runway will negate the whole effect.

This last problem is the only one that I think is at odds with the basic
idea, and I don't have an answer.

But, never being one to criticize without an answer of my own, I propose
the following:  Implement the idea, but use multiple large heating units.
Permanently installed, they could run on natural gas or heating oil, either
one of which would cost hundreds of dollars less per minute than using jets.
Of course no matter what, it's never cheap to heat the whole outdoors!
(anyone who's ever had a parent and a house with a door knows that!)

Foggily,
Dave "Ramjet" Richards

PS.  I don't see any validity in allowing jet engines used in this way to
have the time subtracted from their inspection/maintenence schedule.  The
engine doesn't care whether it's pushing an aircraft or sitting on the ground, 
it has the same load at a given power setting either way.  As a matter of
fact, it may even run hotter because it's not getting the extra cooling
over the outside by moving through the air at hundreds of miles per hour.
Now that I think about it, that may kill the whole idea right there! 

D.R.