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Using a 747 to Fight Wildfires
RotJ writes "It's fire season again. And the government just grounded 33 aging air tankers on Monday due to safety issues. Looking for a modern solution, Evergreen Aviation has come up with a 747 supertanker with 24,000 gallons of tank space onboard, which allows it to cover seven times the area of today's largest existing airtanker. In addition to fighting fires, it will be able to contain oil spills and 'perform challenging homeland security missions' like neutralizing chemical or biological attacks. And think of how many John Goodmans you could cover with fire retardant. Be sure to watch the videos."
How much can you slow down a 747.... would it no make it hard to hit the target at 600mph
Cruise TT
This "11,000-gallon tanker plane pours 'too much water,'". I guess 24,000 gallons (90000L) is not too much though...
Then again, in a flight simulator I've flown the 747 straight up so you could approach the burn and then climb hard while dropping the water.
:)
Do I even need to add anything to make you sound less credible?
I've got more mod points and GMail invi
But I thought 747's weren't particularly strong.
They were strong enough to carry the shuttles around on its back. According to the specs, the 747-400ER has a maximum takoff weight of 910,000 lbs. A fully-loaded 18-wheeler dirt truck averages around 80,000 lbs, to put that into perspective. I don't see how it gets off the ground. 11 trucks are heavy.
And here's the thing, once a fire gets to the size that you start thinking about dropping 24,000 gallons of water on it, YOU'VE ALREADY LOST! Water sure as hell ain't stopping it, unless it happens to be in the form of a severe rainstorm, and even then fires can burn underground for months. There were fires in Yellowstone that started in late fall, got snowed on, smolderd the entire winter underground and then reemerged the next spring.
What the Forest Service needs to do, and to their credit seem to at least be aware of on the ground (at least from my personal experience), is have quick response helicopters that can get to fires before they have blown up (read, still under 100 acres, give or take). Once a fire gets much bigger than say 1000 acres, it starts to create its own weather - at this point, the effort becomes more one of 'figure out where the wind will push the fire and get the hell out of the way!'
The only possible use I see for this plane, and one in which it is probably well-suited for, is in protecting man made structures from large, fast moving fires. Let's say there was a fire bearing down on Denver and threatening a rather pricey subdivision. This plane would be perfect for that job - they could load it up with fire retardant and create a huge 'wet line' in front of the subdivision. Maybe make a couple drops and you would be golden. My guess is that's what they have in mind, but I could be wrong.
One thing the Russians are good at is making things tough. Their design philosophy on military aircraft (including their fighters) is to make them robust to hostile environments including unimproved runways etc. On the surface this looks like a far more economical model using either the Russian or Canadian equipment than to retrofit some used up aircraft not designed for anything like this mission.
When the people fear their government, there is tyranny; when the government fears the people, there is liberty.
24000 gallons of water weighs 99.96 tons.
Load capacity of a 747 is just over 116 tons.
But yeah, that sure is a lot of weight. Amazing aircraft.
"The problem with internet quotations is that many are not genuine" -Abraham Lincoln
"flown the 747 straight up" sounds about as dumb to a pilot as those tech support calls that ask what the cupholder is for to a computer company.
Now, I can't speak for the -200, but as far as the -400 goes, if you fly the 747 straight up in real life, you will in all probability die.
Hi Tom. I'm going to go out on a limb here, and guess that the 747 won't be completely full of water. I know what you're thinking -- that's crazy talk! But I have this funny feeling that just won't go away: maybe the people who think of this stuff have better things to do than make up stupid shit that doesn't work.
I'm just guessing, of course. It's quite possible that the plan involves filling a 747 up with water and watch it sit on the tarmac. That could also be fun.
All tanker delivery systems in use today, except the MAFFs systems (modular airborne firefighting system; military) are capable of multiple drops, split loads, and variable coverage level on every drop. It's part of the basic requirement to field a tank system for use over the fire.
The Evergreen project is being tested at Marana (AZ) now through the middle of next month.
I believe it holds a certain amount of promise, but also some challenges. Like every asset over the fire, it has advantages and drawbacks.
The delivery system is reported to use water injection ahead of the retardant stream to break up the airflow; a fairly complex and weighty soloution to an otherwise simple problem.
The aircraft is swept wing, which presents certain difficulties at low speeds in the fire environment. The concept is of a tanker that makes high retardant or water drops, rather than using it for directly fighting fire. The aircraft will be very limited in the fields from which it can operate, restricting it from being useable at most tanker bases. It also means the airplane will have to make longer ferry's to get to fires, which will give it longer turn around times, greater costs, and may negate any advantages to carrying a greater retardant payload.
Large burning objects fly around over a fire, including trees or parts of trees. A turbofan engine is subject fo FOD contamination by smoke on the compressor blades, but also to direct strike damage from objects over the fire. It is also subject to flame-out, a greater liklihood than a piston engine that has continuous ignition
Drops are typically best done slow; the faster the tanker is moving, the higher the drop needs to be in order to allow the retardant to stop it's forward motion and fall straight down. Retardant moving forward on contact with the fuels only coats one side, an effect known as 'shadowing.' This leaves one side of the fuel unprotected, and negates the value of dropping the retardant.
A fast tanker may need to drop so high that the benifits of the retardant drop are muted. The higher the drop, the greater the drift isue, meaning reduced accuracy, and consequently reduced usefulness.
A DC-4 can be supported by the flight crew; often mechanics who can work on the aircraft as well as fly it. Often a single additional mechanic is a luxury, or all that is necessary to keep the airplane flying. Not the case with a B747.
Maneuverability close to the fire, in terrain with severe or extreme turbulence and reduced visibility may present a number of unique problems for the B747.
If it's viable, the B747 concept (and the DC-10 being fielded by Omni) will present a useful and valueable tool over the fire. It's just one tool, however, and not a soloution of a panacea for other problems plaguing the industry right now. Each aircraft over the fire, heavy fixed wing, single engine fixed wing, light helicopters, heavy helicopters, lead aircraft, air attacks, jump ships, etc, all have important roles. No one aircraft can or should perform them all. Additional available resources such as a B747 only mean that additional tools are available from which to choose when deciding how to most effectively fight a fire.
I fully support any developmental effort to enhance the industry. I tend to take a wait-and-see attitude; these aircraft were never intended to enter or operate in an environment such as the fire ground. Only time will tell what the success of these projects will be.
Back in the 80's, I worked 3 summers as a Smokejumper for the BLM out of Fairbanks, Alaska, and was detailed to the lower 48 on 2 occasions. Smokejumpers and air tanker are considered initial attack resources, so, getting to the fire while it was small and containable was the primary mission. Personally, I find that the aging A-10 aircraft would be more practical than the 747, as it can be forward positioned to the existing air tanker support facilities (Minden, NV being nearest to my neck of the woods/desert), and is fast and exceptionally maneuverable, a requirement for the mountainous terrain of much of the west.
It's the turbulence that causes fatigue, not the action of unloading a lot of water at once. If you think about it, when you go flying in an airliner and you hit a bumpy patch of air, it's usually around clouds. The reason clouds usually form is that air (moist air) is rising, and carrying the water vapor up to a height where the temperature drops enough for the water to condense. The point is, the air is RISING. As the plane flies thru this rising air, the direction the wing is encountering the airflow suddenly changes slightly. Not a lot, but enough that the lift on the wings suddenly increases. The lift (the force that holds the plane up) is a function of angle of the airflow to the wing, as well as airspeed squared. So when you increase the angle of airflow, the lift increases. Now you have more lift than weight, so the plane bumps upwards. But the area of rising air is relatively small, so you get a short transient bump.
Over a fire, you've got LOTS of bumpy air - the fire is superheating patches of air, and it's all bumpy and roiling around. All that mess is rising rapidly into the sky, and fresh cold air is rushing in around the edges (remember Backdraft, the movie?), moving downward.
To be an effective air drop platform, you need to fly very low, so that the water doesn't disperse too much before it hits the target zone. So you're deliberately flying an airplane thru extremely unstable (rapidly rising and falling) patches of air, with very large vertical speeds (which means, larger changes in airflow direction, which means more severe turbulence).
As any materials engineer knows, and as most of us geeks know, if you bend something often enough, it breaks. And the further you bend it each time, the faster it breaks. An airplane wing is designed for a certain "fatigue life" - a certain number of cycles of bending. With the above primer on turbulence, you can imagine how drastically different from the design you will be using the airplane when you fly it 500 ft over a forest fire, compared to relatively smooth air at 38,000 ft.
So watch the amazing video from last year of a C130 losing its wings over a fire - it's a natural but hopefully rare consequence of abusing an airplane this way. The way the airplane owner SHOULD handle this is frequent and intensive inspections. That C130, as I recall, was NOT properly inspected and was well past its service life. You can read the NTSB report on that accident at http://www.ntsb.gov/Recs/letters/2004/A04_29_33.pd f (PDF file). A particularly telling quote: "The rate that maneuver load factors between 2.0 and 2.4 were experienced by firefighting aircraft was almost 1,000 times that for aircraft flown as commercial transports." (Load factor is engineer-speak for "g-force" - 1g is normal gravity; most transports never exceed 1.4g except in severe turbulence.)
--Brandon / Split Infinity Music