lead ballast

Hendrik

You beat me to the answer by a hair.

A very thin hair.

I wonder if 2 post arrive at CR4 at the same time. will they sort if alphabetically or how?

Your a GURU. I'm just a lowly POWER USER. Maybe they go by postings or maybe your just a faster typer?????

Personally I think they should use mercury or platinum for ballast. One would fill the little nooks and cranny's better and the other just looks nicer.

Probably isn't commonly used in many parts of the world these days for that purpose but the primary reasons would be cost, low melting temperature and weight. Melting temperature of pure lead is 327°C and it weighs about 0.41 lbs per cubic inch (which is about 45% more than carbon steel).

Also, it is relatively corrosion resistant.

It can be sheared easily during adjusting. And I suppose one of its main advantages is --- it does not disturb silence being shaken .

Also because it is soft and easily formed to fit whatever cavity or space is available.

Shawn

Another good reason my friend the sailor gave me is that it is readily found on building sites as waste. Therefor it is the cheapest you can get which is for free.

The other reason he likes using it is that it is very easy to correct the weight needed in case of different loads or different sea conditions. Lots of bits of lead chucked in the keel and you can always take a few out or add a few. You start cementing gravel in the bottom of your keel and you would know about it if you wanted less in there next week.

Check out the atomic mass of some of the other elements and take your pick. Mercury would do a nice job filling in the voids of your ballast tanks.

http://go.hrw.com/resources/go_sc/periodic/SSHK1PER.PDF

I will correct myself. Mercurys volume will change with temperature. Nothing like purging the mercury tank on a hot day!

Mercury does not expand more than most other material. It simply flows better than steel and doesn't boil or freeze in the temperature range we live in.

....and poison us all further if the craft sinks......no thanks!!

Uranium has been used, as it is more dense than lead, but lead is more practical and less likely to lead to a visit by Homeland Security.

It is my understanding that DU is used on Boeing 747's as keel ballast in order to save as much space as possible.

DU is also used in the keels of very high performance sail boats. In Canada this requires a permit from the Canadian Nuclear Safety Commission so I assume that the required paper work would wiegh nearly as much as the DU. Then one would have to import the DU because we don't have any enrichment facilities so I can imagine the paperwork on the other end to export the DU and the Canadian customs paper work. Then one would have to find someone with experience working with DU. I have a friend who considered it and gave up.

I have to admit to a misunderstandings:-

What idiot would make an aircraft heavier?

Please comment and put me out of my misery on this point asap, thanks.

DU is damned heavy and probably not as mechanically strong as either steel or what they normally build aircraft out of, some form or alu or similar.....

It is not so much that they need to make the aircraft heavier, but to counterbalance the mass distribution so that the CG is in the proper place, directly over the wing spar.

I hate to say this, but if true, then they haven't a clue how to build aircraft if they need to put in heavy metal to get the C of G right!!!!!!!

To be honest, I simply do not believe it to be true, sorry.......

Are there any Boeing Aircraft engineers that can prove or disprove this claim out there?

I don't know about boeings but glider aircraft have water in their wings to aid the flight characteristics so much so that if they do a record attempt they can carry up to their own combined weight as water in the wings. They seem to fly much better when full of water than they do when empty.

Does not sound like logic but I know it as a fact. If you want to know more do a google on it as I cannot be bothered, sorry.

The reason gliders are ballasted with water is to increase the speed, to increase the distance flown during the available time. For best L/D, the wing should be at the optimum angle of attack. Any attempt to increase speed by "putting the nose down" will increase drag while lift remains fixed. If, however, the glider weighs more, the speed at best L/D will be higher. Before landing, dump the water, and the lighter glider will have a lower landing speed.

Andy, it makes sense when you realize that you cannot always move bulky equipment from where it is needed or will fit to where it would balance best. you also need enough mass at the CG so that passenger movement during flight won't upset the balance much.

APU's or water/sewage holding tanks or flight control hydraulics are all bulky and heavy, and you can't put all of that at the CG. Flight control ball screws must be in the control surfaces. Holding tanks must be near the bathrooms. APU's need to be tucked away in the tailcone to get them out of the way of passengers, cargo and crew. Avionics need to be in the cockpit area. You can't just pile everything on top of the wing spar and call it good.

I also believe that on top of the centre of gravity considerations, they also need a ratio of weight at CG compared to balanced weight spread out. This means that even if the weight is balanced over CG, if the total weight ratio at CG is below as certain degree, they must add weight at CG to compensate. To do with pitch, roll and yaw or something.

Maybe a "real" avionics engineer can help us out here .

that was my point about having enough mass at the CG so that shifts in weight distribution (passengers moving about, cargo shifting in flight, fuel burning off out of fuel tanks, etc.) don't throw the system into instability. you want the ratio of mass at the CG several times larger than the amount of mass that could move during flight so that there is no way that enough mass moving to one side all at once could make the aircraft unstable.

I would add that this is the very same reason why you put ballast in boats as well. You need to make sure the bottom stays wet and the top stays dry, if the CG is too high and/or the ratio is too low, you can't keep the top dry and the bottom wet.

Little hard to get the CG right when you got passengers on board sitting where ever they want unless you can fill every seat. Then all passengers do not weigh the same.

I can see it now if a major airline brought out scales to weigh its passengers to assign seating.

I agree completely with your post, many thanks, I gave it a GA too.

I was assuming (maybe naively!) that an aircraft was designed with all its equipment and tanks so that either full or empty, the C of G would be either be exactly right, or well within the bounds allowed and thereby catered for by the "trim" controls available to the pilots.....

I also assumed that the baggage packers follow some computer generated plan for packing the luggage carriers and exactly where they have to go.

I also assumed that the weight of the aircraft and the weight of the luggage and fuel, are so much greater than the (relatively) minor differences in each passengers weight (fat or thin) that the trim would do the rest!!!

I watched several programs about airbus and they even carefully calculate the cost (in weight) of painting the aircraft!! Every extra kilo is a kilo less fuel that the aircraft can carry, which reduces the maximum distance it can fly...........

Certainly no mention was made by Airbus of adding heavy metals just to get a miscalculated C of G corrected!!!!! I simply do not believe it, sorry.

I truly personally believe that any weight in a modern aircraft will only be added by metals that will only contribute to the strength and safety of that aircraft. Not just in changing trim.....Such errors would force a redesign in the design stage.

WHAT, BOEING HAS JUST DELAYED THE FIRST DELIVERY OF THE 787(?) TILL NEXT YEAR???? Really!!!! What a surprise, the C of G is wrong!!! Go and buy some lead quickly, a couple of tons should be enough!!!!!

Hello Andy and the chap that posted about CG in the first place,

I have just spent a considerable time, about as long as it takes for me to drink my pint of coffee from my German beer mug, searching in various ways for CG correction on airplanes and how they do this.

Although I can see they DO CORRECT the CG, I cannot find any reference to adding heavy weights to the already big planes in order to maintain this CG. I do see they have moving weights to keep the CG stable while turbulence, fuel usage and passenger movement but none says anything about additional ballast in large planes.

I know they do ballast in little private planes as they are much more susceptible to CG shift simply as their total weight is so low to begin with.

I do find evidence of them painstakingly REDUCING the total weight as it means better fuel economy, further flight and or more load.

If anybody has evidence to the contrary above, please let us see it as for now I stick with Andy and think that they DO NOT add heavy weights to large aircraft in order to correct CG. CG is done at design stage and remains within the acceptable range while the fuel is used up or while passengers move about. Don't forget as well that CG needs to be at one point for optimum performance but it has an allowable range. The bigger the plane the bigger this range will be. Also modern planes monitor the CG themselves and counter act automatically for errors.

Good post, I have given you a GA as well.

I think that common sense will win the day and your post and my post are, I do feel, very common sense.

In modern aircraft (I am told) as bits of a plane get relatively heavier in flight (toilet tanks for example), or should I say as other bits get lighter as well (fuel and fresh water tanks), fuel is moved automatically by some on board computers to compensate and keep the aircraft correctly trimmed.

Concord was I believe the first passenger aircraft to have this advanced fuel system which had been only used in small fighter aircraft before them.

Concordski (the Russian look alike screwup) actually exploded in mid air at the Paris air show, trying to do a stylish takeoff - roll and bank etc., as Concord had just done that morning, because the Russian fuel system was not sophisticated enough to allow the aircraft to be thrown about like a jet fighter......(all from memory, I hope its correct!)

Maybe the Russian plane had too much Russian radioactive Depleted Uranium to get the C of G right!!!

With regards to toilets, have you ever noticed how they are spread over the full length of the plane. One bank far up front, one double bank over the wings and one bank at the tail end. This is not really to aid passengers in finding a toilet easily and with little need for walking, it is to assist with CG. Like you said, common sense.

I don't know Andy, what would they do without us

Is this "concordski" for real? That is just too funny to even laugh at.

Please check the following Wikipedia link and click on Paris air show crash:-

Concordski.Paris Air Show crash

I was not kidding, its actually true, but the real reasons may have not come out still, at the time, the bog standard fuel system was blamed.....it did explode in the air, I saw the footage at the time, before striking the ground.

Here is the footage in Black & White:-

Concordski Crash Paris

We actually have one now in Germany, sitting next to an Air France Concord at an open air museum.

Concordski going to Sinnsheim

Paris Air Show crash

At the Paris Air Show on 3 June 1973, the development programme suffered a severe blow when the first Tu-144S production aircraft (reg 77102) crashed. While in the air, it undertook a violent downwards manoeuvre. Trying to pull out of the subsequent dive, the plane broke up and crashed, destroying 15 houses and killing all six on board and eight on the ground.

The causes of this incident remain controversial to this day. A popular theory was that the Tu-144 was forced to avoid a French Mirage chase plane which was attempting to photograph its canards, which were very advanced for the time, and that the French and Soviet governments colluded with each other to cover up such details. The flight of the Mirage was denied in the original French report of the incident, perhaps because it was engaged in industrial espionage. More recent reports have admitted the existence of the Mirage, though not its role in the crash.^[4]

Another theory claims that the black box was actually recovered by the Soviets and decoded. The cause of this accident is now thought to be due to changes made by the ground engineering team to the auto-stabilisation input controls prior to the second day of display flights. These changes were intended to allow the Tu-144 to outperform Concorde in the display circuit. Unfortunately, the changes also inadvertently connected some factory-test wiring which resulted in an excessive rate of climb, leading to the stall and subsequent crash.^[5]

A third theory relates to deliberate misinformation on the part of the Anglo-French team. The main thrust of this theory was that the Anglo-French team knew that the Soviet team were planning to steal the design plans of Concorde, and the Soviets were allegedly passed false blueprints with a flawed design. The case contributed to the imprisonment by the Soviets of Greville Wynne in 1963 for spying.^[6][7]

Don't forget Bismuth -- the non-radioactive element with the highest atomic number. It has a high density like lead, but Bismuth has very low toxicity (Bismuth subsalicylate serves as the active ingredient in Pepto-Bismol). It is also relatively inexpensive. Its one drawback is its brittleness. But still, Bismuth will probably replace lead in many applications (for example fishing weights, tire balancing weights, and bullets).

Forgive me for replying to my own message, but I forgot to mention another important reason that Bismuth will serve as a great replacement for Lead in ballast. Bismuth melts at 271°C (521°F), even lower than Lead which melts at 327°C.

I've posted a better photograph of a bismuth crystal. This unusually large specimen is shown as the actual size. Bismuth, a byproduct from the processing of other metal ores, occurs in nature as oxide and sulfide compounds, not as the pure metal. So these crystals are grown in laboratories from the molten pure metal. Dense, non-toxic, fairly inexpensive, low-melting, beautiful -- what else could you ask for?

I find it totally aBismuth personally....

Cheep! Cheep! add a low melting point and bingo! Counterbalances for rotating equipment are using Tungsten. The MIM industry has begun making bullets using this process with Tungsten. Thats Metal Injection Molding. All the carbide tooling and there respective geometries are made either using MIM or press and sinter techniques.

Tungsten is hell on rifle barrels though. Wears them out pretty dang fast.

They, there must be secret society known as they, anyway the projectiles are coated using copper. There has been some research incorporating polymer coatings in order to reduce the friction between the barrel and bullet. Generally the tungsten or any other heavy metal (interesting movie) is used as the "core" of the projectile. The military has used this technology for armor piercing bullets. These round will generally smoke most body armor. A nasty game this war thing.

But the tungsten "dart" never touches the barrel bore; it is suspended by a discarding sabot. The protectile is much smaller than the rifle bore.

We are talking about two different kinds of ammo and getting them confused in the process. You are discussing the tank killer sabot round used by the M1A2 Abrahms MBT gun. That dart is not tungsten (except for practice rounds) but is DU. It is only about 1-3/4" in diameter and about 18" long. It has a aluminum sabot that flies off after it exits the barrel of the gun and aluminum stabilizing fins that burn off in flight.

We are discussing tungsten rifle rounds for shoulder fired weapons that have a tungsten core and copper jackets to engage the barrel rifling.

Buoy! I dint know this one would evoke so many responses.

Thanks all!

By the way, what would be the next best option to lead, if I cannot use DU and tungsten? Lead melting point may be too low for me. How does antimony respond to corrosive environments?

Google Tungsten carbide counter weights.

Osmium? Bismuth? Mercury/Tin Amalgam? Some combination of the above?

NO! Not osmium. Aside from the cost it is very toxic and oxidizes easily. Before you smell it, you are already blind, they tell me.

I, too, have difficulty thinking Boeing would use DU to fix the CG of an airliner. (The US Air Force has been known to use ballast to move the CG of an aircraft, but they are not as smart as Boeing, and they usually get around to fixing it properly) One place, however, where DU in airplanes makes lots of sense is in mass balancing control surfaces. If the CG of, for example, an aileron is not at the hinge point, accelerations will deflect it and could lead to destructive flutter. Since the internal volume ahead of the hinge point is limited, DU is much better than lead.

If you want cheap DU, help yourself. There are tons of it lying around Iraq, mostly as an oxide dust in the soil, which, by the way, means you cannot safely grow food there. The US uses DU in 30 mm bullets (GAU-8 gun on A-10 aircraft), because they are good for piecing armor (where tungsten used to be used) and, just to add nastiness, upon entering the tank, the DU burns violently. If a crew member should escape the fire, he still faces uranium poisoning from breathing in the dust. (Uranium is a "heavy metal", like lead and mercury, not congenial with healthy bodies. Many think that "Gulf War syndrome" is simply uranium poisoning. About a hundred years ago, civilized countries agreed not to use poisoned bullets, but the 21st century USA is not a "civilized" country)

I'm not sure what tungsten costs now, but from time to time there have been shortages (as during WW-2), and it seems too valuable to use just for ballast.

An interesting aside. Years ago, when I lived in England, the Russians started exporting watches with gold cases. It appeared that the cases weighed more per pound (sterling) than gold bullion, and there was a run on the stores, people buying the watches with the intention of melting down the cases and selling the gold. Ha, ha! The gold contained tungsten, and it could not be melted and purified!

For a non civilised war against non civilised idiots prepared to blow themselves up with dirty bombs, you need an uncivilised response and lots of it my friend.

I am no great fan of some of the American aspects of governing anything nor on some of their foreign policies, but on this point I fear you are wrong and not by a little. Let them kick ass by any means necessary.

Could they use the osmium you don't want?

Case491, in war, there is only one rule: WIN. War is inherently an uncivil act. If, in order to win a war, genocide must occur, cry havoc and loose the dogs of war.

Uranium is found in gypsum as well. Wallboard/sheetrock has to have the uranium removed or it is too dangerous to have in the walls of your house.

http://www.aeronautics.ru/archive/du-watch/us_gov_about_du.htm

http://www.osti.gov/bridge/purl.cover.jsp?purl=/787421-QvK516/native/

It would not surprise me to find that ballast is added to an aircraft to level it out. Whenever a ship undergoes overhaul and changes are made (new stuff added/old stuff removed) weight and moment calculations are performed to find out the resulting lever arm and how much and where to put the non-moving ballast, generally lead. The higher up above, the further to the left or right, or forward or aft of the center of balance, the higher the lever arm and the greater it affects the balance. For example, I once designed an emergency generator/essential load system on a wooden minesweeper (a 179 foot or so ship with a 40 foot beam) and the stuff had to go up on the 03 level out to the port side. Now I don't remember the actual weight of the equipment, but it was not a huge generator; 6KW maybe, been a long time, but what I do remember was that the resulting lever arm was about 200 feet off the port side. I figured I must have made a mistake and redid my caluculations several times, all with the same result. I finally went to see the naval architects who would ultimately combine all the data sheets after all the design work was completed to determine where and how much lead to add. They looked at my work and said I was correct; the height placement of the weight was causing the apparent screwy result.

Also think about a finely trimmed hovering submarine, like balancing a broom handle on a pin. If one person walks from the center of balance to either end, the boat will sink down in that direction. In WWII, firing a 2000 pound torpedos out of the tubes was a call for fast computation and shifting of water to prevent broaching.

Someone on the list has mentioned using mercury because it is more dense than lead. Yeah it is, but I believe when the ship moves, so will the mercury; kinda defeats what you want it to do.

Believe me, there is a world of difference between ships and aircraft.

A ship floats (hopefully !) without using any energy.

An aircraft cannot hover or fly without using energy.

I guess you could say that weight on an aircraft is like having a boat with a hole in it, to stay afloat it must use energy to pump the water out. It just depends on how big the hole is and how heavy the boat is.....

In the world of big business, a change/difference of 0.0001 liter fuel per passenger mile is a disaster for a modern aircraft!!!

I agree there is a vast difference between ship and aircraft, but aircraft ARE ballasted to bring the weight to the preferred located of its engineered center of gravity. Google "aircraft center of gravity" plus "ballast" and you will see that even the Wright Brothers added 70 pounds of iron bar to move the center of gravity on their "new" 1904 flyer.

Fuel is expensive in more ways than one in an uncontrollable plane.

Nobody said they did not use ballast ever. We said they do not add weight to an already large airplane to correct CG. They do have added weights on private aircraft and hang gliders.

We are hopefully also in agreement that you simply cannot compare the first ever flight by the Wright Brothers with modern aircraft. If you thought you could in a technical discussion about CG you would be totally bonkers.

Good answer.

I think we should be a little bit beyond the era of the Wright Brothers with regard to positioning of C of E......what they had to do being the first officially recognized pilots, would not be allowed today....

Any perceived possible need for such fixed ballast today will result in a redesign of the aircraft, as the problem will have been noticed in the design stage before anything is built.....there is simply no way round that....software takes care of that for the designers.....to a great degree at least.

May Erbium be allowed used, instead of lead as a fluid-state ballast control?

Space the less space taken in the holds the more room for cargo. Economics you want to use the cheapest material available. We still have some of the old piers here in which they loaded bricks which they use for ballast.