Sunday, July 8, 2012

Confusing units of measurement and standards

When we were young and under the influence of British colonial rule, we were taught to use all feet, inches, pounds, Fahrenheit degrees and miles etc as our units of measurement. Upon the time when SI units were introduced into our science textbooks for our "O Level Cambridge Examination", we were told to discard all those imperial units and get on with cm, Kg, Centigrade and kilometers etc. Initially I really had a hard time to interpret them when I used to tell my friends that I am 5 feet 6 inches and weigh 150 lbs and now I have to say them differently as 168cm and 68Kg. The Americans are still using the old imperial units and sometimes I could not figure out how cold or how hot is the weather forecast in Fahrenheit while we are so used to the Malaysian tropical mid day temperature of 32 degrees Centigrade and the freezing coldness of minus 4 degrees Centigrade in Qingdao of Shandong China as our frame of references in our mind.

Here comes again another complication about the sizes of the factories that I used to work for. The current plant that I am working is with an area of 8.3 hectares and base on 1 hectare equals to 2.47 acres, and the total land area is roughly about 20.5 acres. 1 acre is 43,560 square feet and therefore to answer a Singaporean who asked me on how many square feet, the Lion Plate Mills factory area is roughly 900,000 square feet. So by the same calculation, the Silverstone tires plant in China is double the size of this, it means to say the land size is now 40 acres or 1.8 million square feet.

We used to have an exchange rate of 1 USD = 2.5-3.0 Malaysian Ringgit or RM and therefore it is customary for us to quote our sales revenue in millions of RM per month. When you are transferred overseas, one has to mention them in US dollars, for example, the Silverstone China plant with a headcount of 580 people was roughly USD 8 millions per month, that of Mexico plant with 800 employees was in the region of USD3-4 millions per month whereas Lion Plate Mills sales turnover with just 180 workers is almost the same as that of the Mexican plant. Steel plate is a bulky item and that accounts for the high sales revenue though with lower number of headcount.

Very often someone will ask me what kind of steel plates that we are producing? We are producing plates complying to the various standards of BS4360 50B or EN10025-2 S355JR, BS436043A or EN10025-2 S275JR, JIS G3101 SS400 and ASTM A36 . This sounds confusing enough? They are just different standards used by the British, Europeans, Japanese and the Americans. We normally omit the BS, EN, JIS and ASTM portions and simply quote the standards as 50B, 43A, S355JR, S275JR, SS400 and A36! Once we have different countries setting their own standards, the confusion starts to creep in!

Our finished products are considered as low carbon steel plates with carbon content ranging from 0.12-0.17. Basically these plates are with Carbon Equivalent or CE between 0.24-0.34. The CE comes into play because some of the other minerals such as Manganese tend to have certain effect on the steel mechanical properties. The CE is defined simply as C + Mn/6. Since we are producing these steel plates mainly as structural steels and therefore the weldability of the steels is important. Generally speaking, the weldability of steel plates with CE of 0.35 and below is good while anything exceeding 0.5 would be poor.

I do not intend to write this as something too technical, just to quote here a few examples of how our minds are confused with all these conversion of units and standards!

Saturday, March 3, 2012

Duration of a flight - battery or fuel

Many new beginners have the notion that by using nitro or petrol engine, filling a bigger tank of fuel could fly the RC plane for HOURS,  and this is not true! Most of the fliers actually fly their planes in the air for half an hour accumulatively and that would be good enough for the fun. Seldom any plane could last more than 10 minutes up the sky per sortie whether it is a nitro fuel or electric powered plane.

I remember those days I bought some Nikko RC cars or trucks for my son and the batteries could only last a few minutes and one had to charge the whole day in order to play again. The technology of batteries nowadays is good enough to send the planes up there for 5 - 10 minutes without much problem.  It all depends on how aggressive you fly those planes and also whether it is a glider that could soar with the wind or thermal column at half or even one quarter of the throttle. And the fast charging time with a balanced charger on a LIPO battery will take only 30-45 minutes. Some of the fliers just plug in the charger to the battery of their cars parked near the flying field. In this way, the electric powered planes become a fast and easy toy of great fun without the hassle of  the need to charge the batteries for long hours and also to clean the oil from the fuselage of a nitro plane.

Just a word of precaution though, all LIPO batteries are highly inflammable. Never ever leave a charging battery unattended or put LIPO batteries in your car and park under hot sun for a long time. They could simply explode and burn your house or vehicle away!

Most of the batteries are rated by MAH, the bigger the value it is, the longer the battery could last, and it also means the batteries are bigger and heavier in weight. One has to consider the space of the plane and also how such heavier batteries could affect the CG and also the lift of the planes. The number of cells of each battery is  denoted by 2S, 3S, 4S etc. Each cell is 3.7 V and when connected in series, 2S means 7.4V and 3S is 11.1V, so on and so forth. Small and light planes are normally using 2S, while mid size planes are usually using 3S and above. 4S, 6S or even higher S are commonly used for those ducted fans fighter plane models.

I have the tendency to fly electric powered planes more nowadays because it is clean and neat, just charge a few batteries at home, and you are ready for the flight!

Thursday, March 1, 2012

Common mistakes when flying a RC plane

Setting up a plane to fly is a meticulous task. I had always under-estimated a lot of little things which I thought were just trivial. When the elevator or the ailerons control surfaces were not fully level or flush, I thought that would be alright and I could perhaps trim them while in the air. Many a times, the planes never get to leave the ground high enough before they crash!

Try to bring along a few planes so that you do not end yourself in a frustrating situation with one faulty plane after driving a long distance to the flying site. Under such circumstances, you have no other choice but try to fly it despite all those small things not in order, which you know the plane is not good enough to be up in the air. If you could not fix it there and then, choose another plane to fly instead.

Other common mistakes include the reverse of the control in one particular channel which could cause a plane which is supposed to go up but plunge downwards; instead of turning to the right, going to the left etc. Do remember this simple concept, when a particular control surface when moved upwards towards the sky by the servo, it means to say more air is passing through and thus reducing the lift that makes the plane staying afloat, therefore it will make that part of the plane sinks as a result of it. So when the elevator at the tail is pointing upwards towards the sky, the tail will sink down while the head of the plane will be lifted upwards during the take off. Since the controls of the ailerons of left and right are moving in opposite direction, the banking of the plane to the right starts to occur, when the servo moves the right hand side aileron upwards, while the left hand side aileron points downwards towards the ground. In the same manner, the movement of the left hand side aileron upwards will activate the plane to bank to the left side to get ready for a left turn. (For more information on how to turn a RC plane to the right and left, kindly read my earlier written article on the topic). By checking the movement and positions of the control surfaces on the ground when moving your control stick, then you will know the setting of the controls is correct, if not just use the program in the radio transmitter to reverse and rectify it.

We have the tendency to forget the rudder most of the time, though we normally use it to navigate the plane right and left just to keep it on track to the intended landing spot. We could not use the ailerons to turn anymore in the landing mode because one has to keep the ailerons flush with the wings on both sides once the plane is flying level without tilting to either side when approaching the landing path. Now try to visualize that when the plane is banking 90 degrees on a "knife edge" style of flying, the rudder now acts as an ELEVATOR and the elevator becomes a rudder.  Thinking along that line, turning with the aileron together with  the rudder at the same time in the SAME direction of the normal sense, thinking we could get a double turning effect from two control surfaces combined would possibly land us into trouble. This could plunge and tip stall the plane. Use the simulator to figure out the effect when using multiple control surfaces at the same time!

One very important part that we must always do, that is checking the CG or center of gravity of the plane. Normally the CG is roughly about one third from the leading edge of the wing, or just under the wing spar. It is better to have a slightly head heavy for a plane to fly properly, it is almost impossible to fly a plane tail heavy. However to fly a RC kite, a slightly tail heavy would be easier to get it manouvred. Always check the CG when you change a battery of different size or weight.

Wednesday, February 22, 2012

RC components - Propeller

I wanted to write a little bit about some of the interesting components of the RC hobby. A lot of the people are actually not so technical as to understand the actual functioning mechanism of those components. I will try  to explain them in a simple way and also quote some examples or analogies so as to make our mind to think it in a simple manner that we could relate, visualize and understand it better, though it might not be technically correct to be so.

We always have a broken propeller resulting from RC plane crashing nose down. Even for a light crash, normally the propeller would break into pieces or bend the shaft of the motor. Therefore it is advisable to have a "prop saver", which is actually a device that one attaches it near to the tip of the propeller shaft and ties the propeller onto it with a rubber band. The propeller shaft is cut and shortened, protruding less to the front so that the impact of the fall would not be transmitted  in full force to bend the shaft, instead the propeller will break loose when the rubber band gives way. It is simple as that!

We are always confused with the various sizes of propellers, and their sizes are denoted by two numbers. E.g.  7x3.5, 8x4.3 etc. The first digit signifies that diameter of the propeller while the second number is the pitch, in imperial unit of inches. Now comes the interesting analogy, imagine that the propeller is a screw, while the air is now the piece of wood. The bigger the diameter of the propeller then you will drill a bigger hole into the air to make way for the plane to pass through. The plane will fly more stable in a bigger tunnel, and more volume of air has to be cut out in order to make that hole bigger. Because of the bigger hole in the sky then the plane will fly at higher speed IF the torque of the motor could handle and displace the bigger volume of air.  Please note the "IF" here because we are talking about a more than enough powerful motor and a bigger diameter propeller will fly a plane faster than a smaller propeller of the SAME pitch.

Look at it in a similar way that if a screw has a fine thread, then the effort to screw it into the wood would be less compared to one with a bigger or wider thread. The pitch is defined as distance traveled per revolution which  is quite similar to the "thread pitch" of the screw. A bigger pitch of thread will require a higher torque from the motor or a screw driver to turn it against the piece of wood because each turn of it will require it to go comparatively deeper into the wood. In the case of RC plane now the air is giving the resistance to the propeller to move forward!  What I am trying to drive at here is that when you break a propeller and could not find the exact size to replace it,  as a rule of thumb, you could find one which is one size bigger in diameter but one size smaller in pitch. In a similar manner if you choose a smaller diameter, you could opt to have a one size bigger pitch propeller. In this way, the motor is not strained as per the original design intended. If we choose our replacing propeller this way, the volume of air cut out roughly remains the same. As the rated output power of a particular motor is a constant, you could not get high speed and high torque at the same time by attempting to play with the selection of various sizes of propellers . So if you want high torque then you have to sacrifice the speed as far as the motor is concerned, and vice versa. Remember the formula of  the power of a motor is equal to Torque x RPM!

Generally speaking when the plane takes off, higher torque is more desirable to climb the plane upwards against the gravity; once it is up the sky, less torque is required and higher speed of horizontal flying could be achieved. Most of the time the combo set we purchase will come with a cheap brushless motor and you will not get both high speed and torque at the same time. If you want both speed and torque, you probably have to upgrade and change to a higher power output motor, this is similar to how we change to bigger cc engines to our cars! We might have to imagine that the MAXIMUM power of a motor is equivalent to the capability of cutting out certain volume of air to allow a plane to fly through the hole, at maximum power output (full throttle), then a smaller diameter propeller should cut a deeper distance into the air and therefore travel faster. Please note it here that the variables to consider are: power of the motor, the diameter and the pitch. To understand them, one has to keep one or two of the variables constant in order to visualize the effect of varying the sizes of the others otherwise we could get very confused over what had been written here.

There is always a maximum size of the propeller that a plane could physically take on. This is because if the propeller is too big, it could hit the ground during take off or landing. While for some pusher prop planes, the propeller is mounted facing the back of the plane, the fuselage, the wing or the space will limit the size that could be mounted. In this case, a higher speed or KVA motor has to be used. For example, with a front mounted propeller RC kite, a 1000 KVA motor with bigger propeller would do the job, while a glider with a back mounted propeller, it needs 2200 KVA together with a 5 x 5 small size propeller.

Please note that KVA rating of a motor denotes the rpm per volt of battery applied to it. If you use a 2S Lipo battery, the voltage is 7.4V while using a 3S Lipo battery the voltage will become 11.1V. You will get a higher rpm for the same motor if a 3S battery is being used instead of a 2S. However one has to bear in mind that with the increase of voltage, we must ensure that the ESC and the motor ampere ratings could take on the extra loading without causing a burn in the electric components or over heating problem. The 3S battery is heavier and bigger size than that of 2S, and for many practical reasons where the weight and CG of a RC plane are to be taken into consideration, therefore an attempt to make such an upgrade of a bigger motor or higher voltage application becomes not possible.

Sunday, February 19, 2012

Some clues on flying RC aircraft for beginners

It was almost a year or more since I started to try my hands on flying RC planes. What I am trying to say is, really flying one without causing a disaster or just up the sky for one circle and the next moment ended up nose down to somewhere in the swamp or tree tops. I had my fair share of plane crashes!

For beginners, we have the tendency  to buy smaller and cheaper planes so that when we crash them, we have the thinking that this will not cause a financial pinch and pain even if we were to write-off and rubbish the planes completely. Actually the smaller the plane, the harder it is for us to handle it outdoor; this is because a slight breeze will severely affect  its stability, not to mention about strong gust of wind, which is fairly common when flying by the seaside or near mountains.  To compromise, I suggest a mid-size, lower speed high wing or curved wing plane with higher angle of dihedral would be a better choice for beginners. An electric plane of mid-size I would consider that as one which has a wing span of less than or equal to 1.4 meter. Some examples of slow electric planes which I flew before are Slow Stick, Soarstar, Phoenix 2000 and Cloud Fly etc. Some of these planes are actually a hybrid of glider and normal high wing plane, which are good for a start in acquiring the basic RC flying skill.

The tricks that nobody could actually teach us are primarily on the control of the plane movement. Theory itself will not help much without actually trying to fly and have a  feel on the planes by ourselves. Some of the clues worth mentioning and sharing here could be useful if you intend to start this hobby:

1. The choice of the transmitters, could be either in mode 1 or mode 2 orientation. Most of us are taught to be right hander since we were young. For this obvious reason, most of us, the dexterity of our fingers are more suited for mode 2, where the left hand of the control is used to activate the engine throttle and the rudder, while your right hand on the stick is used to control the pitch and the roll of the plane, i.e. the elevator and the ailerons. The difference of mode 1 as against mode 2 control is just those 2 sticks are located in opposite direction on the transmitter.

Why I say this mode 2 is generally better, it is because once the plane is fully throttled up the sky to the desired height, you will turn back down the throttle at a fixed position of the stick using your left fingers just to maintain and keep the flying height, thereafter you hardly have to meddle with the throttle anymore, probably once a while just to throttle up a bit against the wind or to manourve the plane for landing. For beginners, the rudder is not frequently utilized other than for sharp and tight turn, or navigate the direction of the plane for landing or  taxiing on the ground. Playing frequently with the ailerons and elevators using our more versatile right fingers on the right hand side stick is good enough to fly the plane in the air most of the time.

I was first introduced to this hobby using mode 1 and now I had changed mine to mode 2. The choice of having mode 2 is not an absolute thing, it is up to you to choose whichever mode you think you could be more at ease with.

2. The trick of turning the plane actually is not just using ailerons or rudder ALONE, which is a common misunderstanding or wrong concept for most beginners. It should be a combination of, ailerons which bank the plane and nose it down a tad bit,  and up the elevator at the same time to execute a smooth and nice turn, either to the left or right! This is an important trick that took me many months to grasp the concept and I finally got to perfect this skill by practicing it on a simulator.

When you start to circle the plane around, choose to execute and pracise it well, either a Left Hand Side LHS or a Right Hand Side RHS turning ONLY for the start. Once you master it say, the LHS turning, then you will know how to turn the plane back towards you if the plane wanders too far away that could lose the control signals. When you sense the plane is in trouble, at least you have the LHS turning skill that you could comfortably fall back to. You just keep on circling the plane the familiar LHS way, so as to give yourself more time to stabilize the plane or summon the help from a more experienced flyer. It is always good to have some experienced flyer to guide you and help you by your side at the beginning.  I owe this very much to Mr. Winston Chu, who had helped to coach me with great patience on the skill of beginner flying!

3. Most of the planes once fine tuned properly using the trims on the transmitter, will fly horizontally in a stable manner (Under no strong wind condition). If you take them high up enough,  and experience a dive or tip stall etc, just let go of your hand on the particular stick which controls the ailerons and elevator, the stick will automatically spring back to its original neutral central position. Under this condition, most if NOT ALL the planes by nature will align by itself and gain its horizontal position once again within split seconds. Please note that do not try this on the plane if it is already too near to the ground, it will not have enough altitude and time to react, it will just crash!

4. Fly the plane in simple turning pattern, then go home and practise with either a Phoenix SIM or Realflight simulator on a computer. You could slowly acquire your new skill of turning to the RHS in additonal to your already skillful LHS turning, After that, go on with a combination of LHS and RHS turnings so called a " figure of eight" flying etc. The advice here is, fly the actual plane, practise with the simulator, then improve on flying the actual plane again , repeat the cycles until you are good at it.

After going through all these, I could now fly the Soarstar right across the small park near to the housing estate that I am staying. It is sheer joy and fun that I could finally able to fly a RC plane.

Wednesday, December 14, 2011

My aquatic plant aquarium

I am developing interest on things that fly in the sky and those swim in the sea. Had my fair share of the RC planes for the past one year and now I decided to go for aquatic plant aquarium.

There are many things and much knowledge to be learnt in order to have those aquatic plants grown well in an aquarium. My usual way to find out those information are actually from internet, forums, friends and also asking my brother-in-law who had planted a few tanks inside his home.

My list of equipment set-up is as follows:

1. I have 2ft and 3 ft tanks reserved for that purpose. My intention is to have an initial hand-on on the 2ft to gain experience and then move on to grow those plants in the bigger 3 ft tank subsequently.

2. Bought a CO2 cylinder with regulator valve and also glass diffuser to inject the gas into the aquarium. An automatic solenoid regulator instead of a manual one would be better because one could use a timer to on and off the CO2 to be delivered. The glass diffuser is a transparent device that one could observe and count the drops of CO2 per minute or second to get the right amount for the proper growth of flora. There is a drop checker that changes its color to indicate the acidity or alkalinity of the water when there is too much CO2 dissolved or too little.

3. Eheim 2217 and Eheim 2215 canister filters. Eheim is a well-known brand though it is a bit expensive. These filters are important for the good biological bacteria to grow inside the media and to absorb and get rid of all those wastes, nitrates etc. The flow rate is preferably 8 - 10 times the volume of the water. For example, if the tank holds100 liters of water then the flow rate of the filters should be in the region of about 1000 liters per hour.

4. An Aquazonic T5 lighting set with 4 x 39 W 10,000K tubes plus 1x 20W 6,000K ADA lamp. The rough guide is 2 - 3 Watt per gallon of water depending on the type of plants that you want to grow. The spectrum of light must imitate closely the natural light source, the color rendering parameter is therefore important for the plants to grow well.

5. A fan that blusters at the surface of the water level to cool the temperature of another 2 C down from the ambient room temperature of 30C to about 27-28 C. The more suitable range for some plant to grow well is probably 25 - 27 C. Some of the more advanced planters choose to use a chiller instead to get the water at a consistently cold temperature.

6. To set up a proper substrate or soil for the plants to take root and absorb all the nutrients required for their growth. This could be an expensive portion of the set-up cost. Based on the more popular aquatic soil brand ADA, one has to put in a layer of power sand, then traces of special elements, the coarse substrate Amazonic sand then the finer powder Amazonic sand. This will set you back for a couple of hundred dollars.

7. There is also a need for periodic dosing of liquid fertilizer to enhance the growth and replenish the nutrients consumed by the plants. The common ones are: N, P, K, Fe (Nitrates, Phosphorus, Potassium, Iron) etc. The available commercial brands in the market include ADA, Seachem, JBL , Sera etc.

Weekly water change is also performed so as to adulterate the fertilizer to avoid growth of algae and also give a suitable water condition for the fauna and flora to live in. The more professional planters might even test the water hardness, PH value, chemical content etc. to get every parameter right for better and healthier growth.

8. One could choose different kinds of fauna or fishes for the aquarium. The most common ones are Tetras and they are beautiful fishes for planted aquariums. Algae eaters such as Siamese flying fox, Amano shrimps etc are also introduced into the tanks to clean up left over food, algae on leaves or glass, drift wood etc.

It is interesting to note some of the very scientific names of the various kinds of flora or aquatic plants. The names are simply bizarre. Just to give examples: Hygrophila Polysperma, Rotala Rotundifolia, Hygrophila Difformis, Rotalla Macranda. Bacopa Australis, Cabomba Furcata, Mayaca Fluviatlis etc. I kept a number of these plants in my aquarium. You probably could identify some of them in the photos below.

There are also some mosses that one could tie them on the rocks and drift woods that form a splendid view of the aqua-scaping foreground or background. The common ones are Java Moss and Christmas Moss. When the right amount of CO2 and light is shone on the plants, they will start to pearl with little bubbles of air releasing and rising up to the surface of the water. It is relaxing to look at them and enjoying the splendid view of a well-planted aquarium

Saturday, August 6, 2011

Beware of such unscrupulous private education institutions!

How could a private institution that promise a degree course of a reputable UK university to be discontinued when they initially offered its diploma program that is supposed to pave way for the admission to its second year degree program after completion? A BIG question indeed!

A lot of these private institutions charge high fees by providing nice and cozy environment just to attract students. And most naive students are easily influenced by the deceptive front facade instead of the real stuff that an education institution could offer, that is, the quality of education itself. They are mainly commercialized institutions all out to maximize profit, cut corners at having enough qualified lecturers for possible subjects students could opt to take on from semester to semester etc. Despite all these, the worst thing one could ever experience would be,  to be told that the degree program is now discontinued after completion of  your diploma. And  you are then advised to carry on the degree program with other alternative universities of different ranking and standard!

I think it is ethically wrong to advertise on educational courses offered from established  overseas universities to lure students in and subsequently default the intended path of the aspiring students! It is either they are not having enough students to form the class economically or having some fallout deals with the UK universities in question. We are not interested to know the actual reason why!

I had told my son to quickly seek out available courses of other more reliable private institutions at the slightest clue of such unscrupulous practices taking place. Imagine a college could accept your registration fees, promise the entrance to start course in September and subsequently want to persuade you to change university? He had wasted 3 months at home waiting for the second semester to start, he was told that ALL of the existing 1st semester common subjects could be exempted by virtue of the earlier diploma program undertaken by him. But in actual fact they are just using the excuse to buy time for recruiting more students. After that period of time, they probably failed to get adequate new student recruitment and they turned around and told you a such a shocking news. When you complain and threaten to take back the deposit, they have the cheek to mention that now the application is being sent to the overseas university and waiting for the letter of offer instead. No one could wait for such nonsense if the entrance criterion for admission is clearly set at a CGPA  score of  2.5 or above!

My son got the offer from another Australian university applied with his result scripts and I told him to go ahead and forget about that RM500 deposit and whatever fees paid!