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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."
The 747 with a gross weight of the 747 of roughly 800,000 pounds is more than that of almost any other aircraft built. The 747 can carry a maximum payload of approximately 144,000 pounds for a distance of 6854 miles and has a cost-economical cruising speed of 564 miles per hour. That's a lot of water in with a short flight time (even if local). And for an airplane that's been around since the 1960's -- not bad either.
747s can go down to 250knots and be managable - heavy load turn stall speed is around 210knots IIRC.
I am not sure a commercial airliner is the best recipe for this problem. In general they are designed to get up to Mach 0.78 - 0.84 and cruise along at 35,000 ft.
A derivative of a military aircraft would be more appropriate. Problem is, by the time the National Guard has used them up (repair costs exceed operating value) there is not much left to the structural integrity.
Bottom line, you get what you pay for. Hearing the dollars on NPR, it is amazing to me that companies were able to keep WWII vintage aircraft in the air for what they make.
When the people fear their government, there is tyranny; when the government fears the people, there is liberty.
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.
But Canadair turnrounds can be as low as 15 mins between bombings, and that is also usefull for ground crews to provide feedback. I think little and often is a better strategy than big drop/big interval.
BTW, the 747 not only needs a significant airstip, you have to get all that water on board and it has to come from somewhere!
True, my knowledge of Canadairs comes from thier use in Italy, where you are never far from a lake or the sea, I can imagine some areas of the US may be different.
And if you thought that was boring you obviously havn't read my Journal ;-)
For years, commercial pilots had to essentially make the "low altitude drop in mountainous terrain" you are speaking of at Kai Tak in Hong Kong. The airport was essentially nestled up against a steep mountain, densely populated by tall apartment buildings and the ocean at the end of the runway. This called for some truly interesting descents and there were "incidents" on the runway but none major, if I recall, before the airport was eventually closed.
Check out this photo:
http://www.airliners.net/open.file/076911/M/
a 747 in full flap configuration can be slowed down to 210kt (approx. 340km/h) IAS fully loaded, and close to 140kt (approx. 220km/h) IAS empty. the maneuverability is a little bit limited, i.e. bank angles over 25 are forbidden. no steep turns are possible, so it takes over 1 minute to do a 180 turn.
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
24,000 gallons of water weighs just shy of 200,000 pounds. A quick glance at the technical specs for the 747 says that the maximum payload capacity of a 747-400 cargo freighter is 244,000 pounds.
ABSURDITY, n.: A statement or belief manifestly inconsistent with one's own opinion.
"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.
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.
AVWeb ran an article about "heavy airtankers" - used ex-Airforce/Navy C-130 and P-3s pressed into service as tankers. From this, we get a weight of 9.3lb/gallon for retardant, for those interested. For our 747, this would be 223,200lb, or 111.6 tons. The most interesting part of this paper is where they talk about the fatigue resulting from the rapid unloading of the aircraft. Apparently, this is the main cause of catastrophic wing failure. When you suddenly change the aircraft load by 15-20%, you get a definite bending action in the wings. Just like bending a paperclip, eventually this leads to failure.
The paper also briefly mentions the super-tanker idea (747 or DC10 based).
The other big concern is that the economic payback for larger aircraft is longer than for smaller aircraft. They were talking about the proposition being questionable with an $8 million acquistion cost. I don't think you could get an operation 747 for anything close to that...
I've heard of proposals like this before. For a while there, the FUSSR was trying to get interest up in Western countries to buy/lease IL-76's for similar duty. FUSSR aircraft might make more sense, they are notoriously inexpensive.
What happened in that 2002 crash was, one of the wings of the plane just sheared off in flight as it came out of a turn. It was structural fatigue, as this article says. The plane involved was just under 60 years old, IIRC.
The pilots got profiled in the papers. Impressive people. Most pilots are flying for the love of it, they get paid next-to-nothing even for the airlines until they have tons of seniority, but these guys were what you'd call heroic characters.
They're truly old planes; it was like seeing a B-24 Liberator at an airshow, only instead of being carefully eased along in their dotage they were still hauling massive loads of water at low altitudes and speed, flying risky in the mountains in this case, for decades after the war. Pretty hard use.
"Fundamentalism" isn't about divine morality. It's about human authority.
A 747 can actually slow to around 120knots, about 140 mph. The standard approach speed for one of these behemoths is around 140-190 knots, depending on the weight. I don't think the proper question is "can the plane go slow enough?" but "can the plane maneuver at low-altitude among mountains?"
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Here's some more reading from a slightly more advanced aviation source: http://www.avweb.com/eletter/archives/avflash/238
Are referring to this? First, trying to get a prop plane to go the speed of sound is something I don't want to try anytime soon. IIRC, you start encoutering problems with the blades and shockwaves. No thank you. Also, that aircraft is fairly tiny. Lastly, it's amazing that the government keeps pushing that plane through testing considering how many accidents in testing that have occured and killed US soldiers. Not too mention the aircraft has had quite a lengthy development cycle.
Why hasn't it been done in Australia?
Distance, expense, distance, lack of water, distance, lack of airfields that can take 747s, and distance.
We use Chipmunks and news helicopters in Western Australia, they cover a tiny area of the 990,000 square miles of WA, one of six states of Australia.
As I said, distance. Fires close to humans get fought, others just burn.
During a fire a few years back, the pilots were using are road as ref. point for heading back to the fire after scooping up a new load of water. These things were passing over our house not more then 100 ft from the top of our roof. With a full load of water then engines make one hell of a noise.
Vancouver Island is home to two other interesting fire fighting planes: The Mars Water Bombers.
The Mars planes fight fires in the US all the time since they are privetly owned.
It can be done. Theoretically, at least. But keep in mind that in some applications, pretty extreme manoeuvers are flown regularly. Take Parabolic flights for example.
Did you know you can fertilize your lawn with used motor oil?
Very doubtfull, dont forget those engines were built to operate at some 30k ft, at a higher speed granted, but check the partial pressure of o2 at that altitude and youll see its still lower than what would generally be encountered at near ground level even during a fire.
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
Bombardier's 415 is an awesome plane and doesn't have the concern of decades-old surplus planes (remember that video from a couple years ago of a C-130 losing its wings during a drop?). From their site:
It takes only 12 seconds, travelling at 130 km/h (70 knots) to scoop up the 6137-litre (1621-US gallon) water load. This requires an on-water distance of only 410 metres (1350 feet). The Bombardier 415 can scoop water from sites as shallow as 2 metres (6.5 feet) and 90 metres (300 feet) wide. This means that a great number of water sites can be used to reload its tanks. The aircraft doesn't need a completely straight scooping path. Since it's still in "flying" mode while scooping, the pilots can maneuver the Bombardier 415 around river bends or avoid visible obstacles in the water. As well, if the water site is too small for a full pick-up, the Bombardier 415 can take a partial load and return to the fire.
In the case of dropping on a fire, it is an ad hoc mission, the pilots would have to eyeball the situation and think on their feet. Also, suppose they count on being rid of 150,000 lbs of water before they need to do a climbing turn at the end of a valley and a hydraulic valve sticks? The only good news as that 25,000 gallons of water would help extinguish the 30,000 gallons of jet fuel.
The wind conditions around a forest fire are also dangerous. Fires create their own weather.
When the people fear their government, there is tyranny; when the government fears the people, there is liberty.
http://www.avweb.com/eletter/archives/avflash/238- full.html#187301
Forest fires typically occur in mountains. Mountains are usually between 1,000 feet and 13,000 feet tall (300 - 4000 meters). Forest fires usually occur in the summertime. Forest fires make a lot of hot, dry air. The net result of this is a substantial increase in the density altitude in the region around a forest fire.
The density altitude is the altitude the airplane "sees" - taking into account air density, temperature, humidity, etc. Above a 5,000ft density altitude (~1,500m), most airplanes have a hard time just taking off with a full fuel load, much less performing high-g maneuvers close to the ground. At Las Cruces, New Mexico, the airport here is at about 4,500ft (1,370m) mean airfield elevation. Density altitudes above 7,000 feet (2,130m) are not uncommon - even early in the morning.
To operate under these conditions, pilots simply reduce their passenger and fuel loads. I haven't done the math, but I suspect that to make a 747 light enough to operate safely "down low" at a high density altitude, it wouldn't be able to carry much more water than the C-130 tankers we already use. Plus, a loaded 747 would tend to perform like an elephant on ice skates - a consequence of its swept wing and turbine engines - which don't "spool up" as fast as props. There would be zero margin for error.
This sig is a test. If this had been an actual sig, you would be reading something quite a bit wittier than this now.
A B-52 would be better. It is already low level qualified for years ( low level bombing with high drag dumb iron, ) and has a modern enough bombing system to have the ballistics for the water / chem package slewed into the computer, so as to hit any location a forward air controler calls in. Plus the crews out of Barksdale and Minot ( the 2 B-52 bases ) could still get decent training hours.
Why try and reinvent the wheel?
Helicopters serve a variety of uses. One of our main jobs was elevator service. Some areas we worked in had fires extending up 2-3000 feet of steep hillside without trails in thick brush. We also hauled our share of heat-strokes, turned ankles, and other medical types.
However, the comment about helicopter water-carrying capacity is fairly accurate. In general, helicopters have much faster turn-around time and much greater accuracy for cooling hotspots, but are useless for a big running fire. Then again, almost NOTHING we can do actually stops a running fire. A change of weather, running out of fuel, and winter are the best bets.
We carried 12'x12'x4' collapsible tanks with a trash pump. The helicopter could get to a fire well ahead of trucks, I'd chainsaw a clearing next to a stream, set up the tank, and we'd be dipping water inside half an hour while the trucks were still grinding up logging roads to get to the fire. Our waterholes were any stream or lake in the area. In some cases, I'd have the deck chair out next to a stream watching the helicopter drop 250 gallons on leading edge hotspots every two minutes, just long enough to dip, lift 500', drop and dive back down.
As a side note, it gives you a good jolt to drive a truck loaded with 750 gallons of jet fuel down a road lined by burning trees. It's not actually all that flammable, fortunately. The 100 gallon side-mounted gas tanks were probably a bigger risk.
... grumble, grumble, grumble, mutter, mutter, Millenium... Hand... Shrimp, I tol' 'em, I tol' 'em.
The fuselage of the Buff isn't really shaped properly for the job of tanker, and would require massive mods.
C-130s work fine. Just retire more of the early 1960's fossils from the active inventory and buy the USAF more C-130Js.
With a larger payload, you can probably afford to drop from a higher altitude.
You'll have a tough time selling that theory to the firefighters who are on the ground.
Precision is still very important, not just to conserve payload, but to get the payload in the right spot.
--
Boeing is working on something similar to this, IIRC. A version of the jet-copter from the Sixth Day (really bad Ah-nold movie). It has a rotor that translates to fixed wing, and has jet engines in back. It's initially going to be used for small UAVs, not passenger craft.
r y/unman ned/x50.html
Slashdot had an article on it last year, IIRC.
http://www.boeing.com/defense-space/milita
Divide the bucket into two sealed compartments. Fill one compartment fully with water, while leaving the other one empty...
Given that planes have been used in fighting fires for rather some time now, I'm guessing they have considered the problems.
Actually, who bother with a Boeing 747 is may not be structurally sound for low-altitude firebombing missions?
Recently, Boeing proposed an idea of using C-17A Globemaster III transports dropping 2,800 beachball-sized containers filled with water or fire retardant in a wide pattern some 2,000 feet above the fire. This means you could deliver up 144,000 pounds of fire surpressant in a wide pattern, which means more of a fire can be quench with such a plane. And because it is dropped around 2,000 feet in the air, that means the plane will fly in far less hazard conditions than firebomber planes do now.
If you check out the Popular Mechanics web site, the proposal is mentioned here: http://tinyurl.com/2otpd
Another interesting proposal is to bombard a fire with artillery sheels filled with liquid nitrogen. Why liquid nitrogen? Because it has these advantages: 1) the extreme cold of liquid nitrogen will quickly slow down a fire, 2) the presence of that much nitrogen gas expansion will snuff out the oxygen needed to feed and fire and 3) liquid nitrogen quickly boils away, so you don't have an enviromental hazard like you do with some chemcial fire retardants.
A few years ago, a friend (hi Mike!) took my gf & i to CAE's flight sim shop over the christmas holidays. We got to play on the static sim - used to test graphics and to sell their airport sims to prospective customers. It's a normal enough room with some laptops, except there's a stripped-down cockpit where one wall should be.
We did a few a few TOs & landings at various airports (including a gorgeous 20 km approach in the Alps somewhere) For the last one, he dialed up Kai Tak for us. Absolutely insane. There were landing lights on the apt. buildings, curving through the city. It's true you can see into peoples windows. Anyway, i almost made it; though i'm sure i still never would have corrected enough to put it down properly if i hadn't sheared off several floors of one building.
Very nice pic, btw. I did some googling and found this page with Kai Tak photos. Scroll to the middle for a video to make you giggle insanely. (warning: lots of images and absurd amount of javascript. Here's the link to the video) If you'll be flying anytime soon, i leave it up to you to decide if you want to see this*. Notice, also, the concordes - does anyone know how they handle differently than a 7*7 on approach? I imagine that would have been trickier.
spoiler: * there were never any accidents at Kai Tak.
"Our interests are to see if we can't scale it up to something more exciting," he said.