WEIGHT AND BALANCE . . .
By Chris Murray 1944 E. Pegasus Tempe, AZ 85283
I HE COMPUTER AGE is here. The number cruncher hs arrived. In my last article, I introduced builders to the use of home computers with a simple program to calculate sheet metal bend allowances. Thinking that I'd perhaps slighted the owner/pilot who bought or has already built a plane, I've written a short program to help do weight and balance computations. The program listed in Part 2 of this article can be used for pre-flight planning or for the removal, addition, and/or moving of aircraft components. The program is generic enough to run on virtually any computer. No provisions are made for hard-copy printouts, but that can be added at the user's discretion. In Part 1, I will give a refresher on weight and balance theory and effect on aircraft. Those of you who feel very comfortable with weight and balance already will need to wait until next month to get the program. Weight is an element that affects all of us in our earthly pursuits. We're aware of it from the first thing in the morning when we step on the bathroom scale to the last thing at night when we sink into the nice soft bed. Aircraft have weight, too. Like our own weight, it's usually enough, or in the range that the builder wanted. Other times there is too much weight on the frame. We can easily see when we personally have a weight problem, but it is more difficult
to tell when an airplane is heavy. Complicating the weight picture is the center of this weight. Too much in the paunch and we tend to fall forward, and taildragger aircraft fall on their noses. Too much in the rear and we (and planes) want to sit backward. Thus, for humans and airplanes alike, weight, and the distribution of weight, called balance, are of significant importance. And we can control both factors in ourselves and airplanes. If you want to know about personal W & B, see your doctor. I'm here to talk primarily about your plane. The weight component of the airplane is important for two reasons. First, if there's too much, you have a noisy, impractical car, for the plane will never get out of the taxi mode. In that condition, you might as well take off the wings and register it with Motor Vehicles, for it will never fly. The second point: if acceptable weight is distributed incorrectly, the plane may fly but be unstable to the point of being a danger to those in it and those on the ground. Weight and balance are not the only factors that determine stability or instability. This discussion concentrates on the effects that weight and balance have on aircraft stability, control and performance. Technically speaking, there are two types of weight we will deal with: empty weight and gross weight. Empty weight is all those items that make up the basic aircraft. (Note: Preflight weight and balance formulae usually start from HORIZONTAL DATUM
FIGURE 1. BALANCED AROUND THE CENTER OF GRAVITY. 40 FEBRUARY 1985
FIGURE 2. THE THREE AXES.
the premise that the empty airplane is just that: empty. No pilot, no fuel and no oil. Only residual or unuseable quantities of oil and fuel are part of the empty weight. Therefore, you'll need to know your oil capacity in quarts and the gallons of fuel to be added to the tanks.) Gross weight (or sometimes maximum or maximum gross weight) is the maximum authorized weight of the aircraft and all its contents. (Notice that the definition does not specify in flight or.a weight that the aircraft can lift.) Gross weight minus empty weight gives us the aircraft's useful load or how much we can legally pack into or onto the plane. Aircraft manufacturers establish the desired empty and gross weights of any projected airplane when the design goals are first conceived. Regardless of the plane's as-built empty weight, the plane is designed and constructed so that at its gross weight, it will hang together under virtually all normally encountered flying conditions (thunderstorms, tornados and hurricanes excluded). If a plane is to be used for aerobatics or hurricane chasing, it's built more stoutly, but the percentage of gross weight to empty weight decreases as the structure is strengthened. To allow more weight to be loaded onboard, the aircraft is made larger and fitted with bigger engines. Under certain atmospheric conditions, the aircraft may not be able to lift off the ground at gross weight. If it can, we don't need to worry about structural failure unless we cause the problem. The designer of the homebuilt similarly shoots for constructed empty and gross weights. The prototype usually comes in near the empty weight and is limited to the designed gross weight. However, as various builders make their own versions from the plans, empty weights vary all over, depending on the materials substituted, or on gauges, electronics or modifications added to the original design. Gross weight limits remain the same. Some builders, facing a reduced useful load capability, install bigger engines or
lengthen wings to lift an increased gross weight off the runway. Hidden in this
approach is the possibility of pulling the wings off in a maneuver that would be safe for the same airplane at its normal gross weight. Changing the gross weight capacity
WEIGHT ARM_____|
} 50 LBS.
10"
requires the analysis and change of
n
several interrelated components and
25 LBS.
structures. Best to either build lightly
and limit your accessories, or build an
airplane big enough to carry everything
20"
you want. If you're stuck with a reduced useful load, it will be easier to reduce what the plane's required to lift than to redesign it. Less baggage, less fuel and fewer people all help keep the plane at or
.05 LBS.
10,000"
below its gross weight. For the purposes of flight planning, the FAA has
set the typical pilot/passenger weight at 170 pounds. Personally, I have to give up 5 gallons of fuel to carry my non-typical body. So, if the fuel, bags and numbers of bodies still have to go, reduce the weight of the bodies. (Again, see your doctor.) Prior to each flight, wherein the airplane is to carry more than the pilot,
an analysis of the loaded weight versus gross weight should be done. (Of course, if the plane is a single-seater that is weight-critical, you should do this check anyway.) Using addition and
subtraction, the pilot totals the weights of all components to arrive at a loaded weight. If your plane can be loaded beyond its gross weight easily, or you fly in areas of high density altitude, it might be a good idea to keep a bathroom scale in the trunk of the car. Then, for a trip, each person, with coats, cameras and books, can be weighed prior to loading the plane. Similarly, all baggage and extra gear can be weighed before stowing it onboard. If these added weights, plus the weight of fuel and oil, total more than the gross weight or than
can be lifted on that particular day, you
can begin offloading things before the
situation gets really sticky. I've lead you this far with the easy part of weight and balance. We're all conscious of weight, but our balance control is left to the inner ear, so we're not as skilled in this more abstract portion. To talk about balance, we will need to use some commonly accepted, but often vaguely understood, vocabulary. As in all fields, common agreement on words and terms to be used helps all involved communicate more clearly. Besides, you can impress your non-flying friends more easily. Balance is simply a point somewhere in the airplane such that if the airplane
were suspended on a cable attached to
this point, it would not tip or try to fall one way or another. (See Figure 1) The balance point of a ball, for example, is its exact center. This point of balance is the center of gravity, or CG. Because
FIGURE 3. DIFFERENT WEIGHTS, DIFFERENT DISTANCES, BUT SAME EFFECT ON DATUM. ITEM WEIGHT x ARM = MOMENT CUBE A 50LBS 10' 500 CUBES 25 LBS. 20"' = 500 CUBEC 05 LBS. 10.000" = 500
the CG does exist, it can be located. The CG is the intersection of three
axes: fore-and-aft, side-to-side, and upand-down. The fore-and-aft axis is the most important and is used in weight and balance calculations for flight planning. The longitudinal CG is located by measuring along a straight line parallel to the line of flight, measured from a vertical line called the datum line, or more simply, datum. (Datum is a classy Latin word meaning a given point to measure from.) The distance from datum to the CG, or any other point in
the airplane, is called the arm. (See Figure 2) Each axis has a datum line from which to measure.
The side-to-side, or lateral, axis is a line parallel to the wing tips and is used to locate items on either side of the center of the aircraft. And, logically, the datum line for lateral measurements is most frequently the centerline of the aircraft. The vertical axis runs at right angles to the other two axes. The datum line for measurement is a horizontal line usually located below the plane. One might assume that the ground would be the point to measure from, but think
how the measured location of things
would change if the airplane were empty or partially loaded. You might as well try establishing a definitive measurement for "high". The CG, or point of balance of the aircraft, will probably not occur on any
of the axes. It's exact location can be found by weight and balance computation. The longitudinal CG, as mentioned, is the most important, for adding people, bags, and fuel will move it backward or forward, with a resulting effect on control. Shifting the CG side to side can be done by flying solo in the right seat or flying with a full right wing tank
and an empty left wing tank. The effects solo are usually barely noticeable, and proper fuel management will eliminate any wing-heavy feeling. Vertical CG shifts are hard to accomplish. The best illustration of this shift would be putting boxes of feathers on the floor of the baggage compartment and stacking heavier and heavier boxes on top. This makes the airplane "top heavy", and its flight characteristics will change a little. Heavy weights low in the plane make it more stable. For the purposes of this weight and balance discussion, I will deal only with the longitudinal CG. All the theory and calculation techniques are applicable to the other axes. Now that balance, datum and arm have been reasonably well defined, I'll muddy up the picture a bit. There is NO standard place for the datum. It's wherever the manufacturer or designer says it is. It may be at the firewall or prop spinner on an airplane, or at the rotor
mast of a helicopter, or even a foot in front of the aircraft. The Type Certificate Data sheets for manufactured aircraft must specify the datum location. Designers of homebuilts should specify one for each type of plane designed. If you're building an original design, you'll
need to establish one. With the airplane in an attitude of normal flight, pick a
point on a horizontal line parallel to the line of flight that isn't likely to be moved
or changed as the plane is modified.
Such a location might be the firewall or the leading edge of the wing. With an established datum location, or one that you've just defined, CG can be calculated. Traditionally, all points between datum and the tail of the aircraft are positive numbers and locations
the opposite direction from datum are negative. For clarity, I'll continue the tradition. (Continued on Page 85)
SPORT AVIATION 41
WEIGHT AND BALANCE . . . (Continued from Page 41)
In all probability, you're familiar with the acronym "IWAM", but tend to confuse it with some Middle Eastern country. "IWAM" stands for: Item's Weight times its Arm equals its Moment. Moment is the last term requiring definition. Moment is the mathematical product of weight and distance that represents the bending force applied at the beginning of the arm. It is used to help determine an item's effect on the location of the center of gravity. Three items, each of a different weight, can all possess the same moment. To do this, they must be different distances, or have different arms, from datum. (See Figure 3) The closer that an item is to the CG, the less effect on the balance of the WASHINGTON REPORT . . .
(Continued from Inside Back Cover)
before you reach your destination. Which of the five alternatives best illustrate the RESIGNATION reaction? 1. You feel there is no need to worry about the weather since there is nothing one can do about it. 2. You immediately decide to continue and block the weather conditions out of your mind. 3. You feel nothing will happen to you because you have plenty of fuel. 4. You think that the weather people are always complicating your flights, and sometimes, such as now, it is best to ignore them. 5. You fly on, determined to prove that
aircraft that item will have if it is added or removed. This is why fuel tanks in the wings are advantageous. The CG frequently is on the same lateral axis as the fuel tanks, and as fuel is consumed, no trimming is necessary for the CG moves forward or aft very little. You would, however, notice a CG change if you drained one wing tank. Now, the CG moves laterally toward the wing with the fuel and the plane begins banking that direction. Horizontal CG is still the same; it just moved sideways. As a review, empty weight is the weight of the aircraft with all permanent equipment and residual fuel and oil. Gross weight is the maximum that the aircraft is permitted to carry based on its structure and power. The point of balance is called the Center of Gravity
(CG), and all weights in the aircraft are balanced around this point. All points in or on an aircraft can be found by measuring from a datum line. The measurements are made parallel to the horizontal, vertical and/or lateral axes. For balance calculations, the arm of a component is the distance from a datum line along a line parallel to one of the above axes to the center of the component. The moment of an item is the item's weight times its arm. The sum of all moments is used to calculate the location of the CG. Now that you have refreshed your memory banks on weight and balance concepts and terms, you're ready to begin using the formulae and the computer program, which will be the focus of next month's article.
your own weather judgment is sound. And, finally, the lesson is: I am not helpless, I can make a difference In addition to the student handbook, GAMA, Transport Canada and the FAA have prepared another prototype handbook for flight instructors based on the curriculum of the student handbook but showing how these principles should be taught. An instrument training handbook is already under development by Ohio State University Handbooks for Multi-engine and Multi-crew pilots may be developed. Preliminary results show that newly certificated pilots who had been given judgment training made 83% of correct decisions in judgment situations compared with a grade ot 43% for those students who did not take the judgment training.
The label "judgment" as it relates to these programs will be dropped and changed to pilot decision to reflect a much broader outlook on a whole host of human factor issues that contribute to this high 85% accident rate. Subjects for these new control areas include decision making under stress; risk assessment and risk reduction management; cockpit organization and cockpit task management and crew coordination for multi-pilot aircraft. A major meeting to discuss all these subjects is planned for March 1985 to be held in Washington. From the above details it can be seen that this is indeed a fresh approach to pilot training. So far, the results look promising towards increasing the level of pilot judgment and therefore safety.
FORD TRI-MOTOR
WANTED
Limited Edition
C O L L E C T O R S of A V I A T I O N MEMORABILIA
Shown here is the actual 1929 Ford NC8407 wall plaque with corrugated alumi-
This collectors package includes a rare 1927 brochure reprint ot Ford suggestions tor In-Motor use. circa 1927
EAAs Ford Tn-Molor will be flying soon1 The wings are installed, engines installed and new exterior finish sparkles Interior appointments, gold trim and new seats are in place, the same as it left the factory in 1929 Ounng the restoration some of the corrugated aluminum was replaced and these remaining 'onginar pieces have been mounted onto a limited quantity of commemorative "numbered" plaques. The first flight is being planned now and all of us will be seeing this historic aircraft flying again!
num artifact, etched photoplate and Ford nameplate
This entire otter, including a personalized certificate and a book on Ford history by EAA. is available for $100.00 postpaid to your address or as a gift, mailed directly to requested address. Send your tax deductible contnbutron to the Ford TrtMotor Limited Edition Fund.Wittman Airfield.Oshkosh, Wl 54903-3065 Checks should be made payable to EAA Aviation Foundation
SPORT AVIATION 85
CPmPUTER
Programs For HnmebuildErs
WEIGHT AND BALANCE BY COMPUTER PART II
By Chris Murray
1944 E. Pegasus Tempo, AZ 85283
I Hi: •MS IS PART 2 of an article begun last month covering weight and balance theory and a computer program to do preflight and equipment change weight and balance computations. Because this is a magazine primarily for homebuilders, and because each new aircraft needs to have a weight and balance check done for certification, I'll use the initial weighing procedure as my first example. Using Figure 1 as reference, imagine the Shinbarker II stands ready to be signed off for certification and flight. Datum is the tip of the prop spinner. Estimated design values are: Empty Weight - 655 Ibs., Empty - CG-52 inches, CG travel - 45 to 61 inches, Gross Weight - 1600 Ibs. Scales have been put under each tire and the plane adjusted up or down on the scales until it is in a level flight attitude. (Note: Block the wheels so that you don't ding the plane or yourself when it rolls off the scales.) Next, measure the distance from your datum point back to the center of each axle. Be sure that you measure parallel to the line of flight and to the centerline of the plane. Naturally, the distance for the two main axles on traditional aircraft with three wheels is the same. Record the distance to each axle/scale and the weight indicated on the respective scales. In Figure 2, you can see the measured arms and weights. The arms are all positive numbers because the scales are between the datum and the tip of the rudder. The weights are all gross empty weights and may need to be corrected. If you used blocks, stands, chocks, etc., you will need to subtract the weight of these safety devices from the weight shown on the scales. Remove the aircraft from the scales, and then place back on each scale all of the chocks, stands, etc. that were on that scale while the aircraft was being weighed. Subtract the new weight (called tare weight) on each scale from the gross weights you previously recorded. You now have the net weight of each axle. The sum of the three net weights is the airplane's empty weight. (Write it in the log book now so that you won't forget it). See Figure 2. The net weight and arm of each scale are multiplied to give the moment of 48 MARCH 1985
Left Scale = 310 Ibs. Right Scale = 322 Ibs.
Tail Scale = 68 Ibs.
FIGURE 1.
each axle. All the weights are added (empty weight), and all moments are added. Finally the total moment is divided by the total empty weight and, presto, we have the invisible, but, oh, so important CG at 50.6209 inches, or 501/2" for us loose flyers, behind the tip of the prop spinner (datum). Half of the plane's weight is in front of this point, and half behind. Make a note of the total moment and the CG location in the aircraft's airframe log book for use by you and future owners. See Figure 3. The empty weight and empty weight CG should be close to the specifications given by the designer. If the aircraft is too heavy, it's almost too late now to make the components lighter or leave radios out. If the CG's off, changing the location of components, like batteries, can put the CG closer to the desired point. It's best to get the CG at its designed location as take-off and landing
Axle 1 Ax 1 e 2 Ax 1 e 3
characteristics can be affected by variations. In some situations, the builder sets an approximate location for the battery installation, but does not install it yet. With the battery placed where the builder figures it should be, an initial weight and balance study is done to find the CG. If the CG is farther aft than desired, the battery is moved forward until the CG is closer to its desired location. The battery is then permanently there. Battery movement is frequently used to move the CG in helicopters, which have a very narrow CG range. In some extreme cases, lead ballast has to be permanently mounted to the structure of the aircraft. This is unfortunate for it reduces the useful load of the aircraft. If you must use permanent ballast, be sure that you make a clear record in the log book that ballast is required. Someone three owners hence may remove
NET GROSS TARE WT WT WT 310 8 •= 302 322 8 - 314 54 68 - 14 = FIGURE 2.
ARM 37" 37" 206"
AXLE 1 AXLE 2 AXLE 3
WI 302 314 54
X X X
ARM 37 37 206
MQMENI 11 ,174 11,618 11,124 33,916
670
CG - 33,916/670 = 5O.62O9" FIGURE 3.
that ugly chunk of metal and end up destroying an otherwise good aircraft. General design practice is to place the CG ahead of the center of lift of the wing (see Figure 4). In straight and level flight, if the elevator were parallel to the line of flight, the aircraft would tend to pitch nose down into a dive. To counter this, the horizontal stabilizers are typically mounted with their leading edge down, as in the drawing. This forces the tail down and the aircraft's nose up. If speed is increased, lift increases, overcoming the effect of weight, and the nose comes up. Decreased speed equals decreased lift which equals pitch down. Back to the CG itself. As the CG is moved toward the center of lift, less effort is required to control the aircraft. As the CG moves away from the center of lift, the more you as pilot have to work to change, or sometimes, even maintain control. Too far forward, and you may not have enough elevator travel to hold level flight. Release back pressure on the controls and down she goes! Too far aft and full forward stick may not bring the tail up. In flight, this means that the plane will continuously want to pitch up. On the ground, a taildragger may do no more than run up and down the runway in a three point stance. Therefore, for your health, it is very crucial that the CG be kept within its forward and aft limits. It should be mentioned again that even if the CG and the weight of the aircraft are within their limits, the aircraft may be unstable in flight for other reasons such as elevator arrangement, control slackness, etc. Many factors contribute to the safety and stability of flight, and observing weight and balance restrictions are but two. The manufacturer has set a range of travel that the CG can move within and allow the aircraft to perform safely. Some aircraft are tolerant of a large CG range. Others, particularly helicopters, are extremely sensitive. The next thing you should do with your new airplane is check the CG travel. This means that you calculate how far you can get the CG to move with various loading patterns. (I'll show
you the longhand method, but the program will make this a snap.) I'll first determine the aftmost CG location for the Shinbarker, which was specified as 61 inches. To do this, all items located or loaded behind the empty CG are added to the plane and all items in front of the empty CG are removed or reduced to a minimum. My plane's fuel tank is just behind the engine, so I'll figure that it's nearly empty. The pilot and copilot sit ahead of the CG, so only the pilot is going. The two passenger seats and the baggage compartment are behind the CG, so two 170 Ib. people and maximum baggage (200 Ibs.) are going. See Figure 5 for the calculations. As you can see, the new CG is too far aft of the allowable range. By removing 115 pounds of baggage, I can get it back within limits. The forwardmost CG check is done the same way. All items in front of the empty CG are maximized and everything behind the empty CG is minimized or left out. It may be that with full fuel and heavy pilot and passenger the forward CG is exceeded, but the gross weight is not. To fly in that configuration, you may have to add rocks or tire chains to the baggage compartment to bring the CG back within its range. Whether or not you are able to load your plane in such a way to move the CG beyond its range, you must know if it is possible, and what it takes to exceed the range. Then you can determine what to do to
mander 680 is so close to the rear landing gear that when the tail is pulled down to the ground, the CG moves to a point behind the rear gear, and the plane will sit there with its nose in the
air. Imagine loading a 680 with a light pilot, half fuel, a couple of passengers
in the rear seats and a full baggage compartment. It'll assume a take-off angle of climb even before the engines are started. The concentration of weight behind the landing gear also moves the CG behind the gear, and the plane in this instance rocks backward. A preflight weight and balance check is simple and straight forward. The
weights of all the added items (fuel, oil, pilot, passengers, lunches, etc.) are added to the empty weight of the aircraft and compared to the specified gross weight. The moments of all items are calculated and added to the moment of the plane. This total is then divided by the loaded weight to give the loaded CG location. Is it within the CG range? Is the aircraft overloaded? Part of the attached program will do this for you. It asks for the pilot and passenger(s) weights, the quantity of oil and fuel loaded, and the weight of
maps, books, baggage, tents, etc. you
plan to carry, and the arm of each. Equipment changes also move the CG. Changes, though, are not simply adding weight. Components can be removed, added or changed from one place in the plane to another. Now weights and moments may be added or subtracted, or the weight remains the same and the moment and CG vary. When using paper and pencil for calculating, weights to be removed should have a minus sign placed in front of the weights to indicate removal. Added weights are positive in value. The weights are added or subtracted from
the plane's weight as indicated by the
sign. Calculated moments are added or subtracted as per the sign that results after multiplication. Weights that are moved do not affect the empty weight, but their moments must be calculated, the moment of the old location sub-
remedy the problem.
Any changes in the equipment of the aircraft will affect not only the empty weight, but also the location of the CG. By equipment, I mean items that cannot be easily shifted or removed from the airplane, like radios, snow skis or large tires. It's easy to visualize how adding a bigger battery or nice new NAV/COM or LORAN changes the empty weight, or how gross weight can be exceeded by carrying that moose carcass in the baggage compartment. It's harder to see the CG moving as equipment or baggage is added. That is why doing the balance calculations before flights or after the equipment list is changed is so important. The CG of the Aero Com-
Gravity FIGURE 4.
Relation of Center of Gravity and Center
of lift on straight and level flight.
SPORT AVIATION 49
tracted from the moment of the new location added to the plane's moment. But that is all too complicated in this day and age. Just type in the program, save it and run it. It will ask for the quantity of items to be changed. It will ask what to do with each. Just enter the weight(s) and arm(s) as necessary, and the number cruncher does the rest. (Be sure to put a minus sign with any arm distances that are ahead of datum. If you are building a new plane, why not put the horizontal datum at the tip of the prop spinner? Then all arms are positive values. If a datum has already been established, the one set by the designer or manufacturer should be used to avoid confusion.) With the preflight calculations as well as the equipment changes, if the gross weight is exceeded or the new CG is outside the CG range, a warning to that effect is printed out. No provision was made in this program for hard copy printing, but using my bend allowance program, you should be able to modify the "Print"
HIM Aircra-f t Pilot
Copi lot 2 Passengers Baggage Totals
70 PRINT "HHAT IS THE PLANE'S BROSS HEIGHT"; 80 INPUT SHiPRINT
90 PRINT "HHAT IS THE PLANE'5 ARH"; 10C INPUT PA:PRINT 110 PRINT "HHAT IS THE PLANE'S FORNARDHOST C.G. LOCATION1; 120 INPUT FCB:PRINT 130 PRINT "NHAT IS THE PLANE'S AFTHDST C.S. LOCATION"; MO INPUT AC6-.PRINT
150 PRINT "IS THIS A (O)PREFLIGHT, DR (DEQU1PHENT CHANGE")
160 INPUT TJ-.PRINT 170 IF T« = "f THEN 60TO 440 180 REH COLLECTING PREFLIGHT DATA 1?0 CLS:PR1NT "HO* KANY PEOPLE, INCLUDING PILOT, ARE ONBOARD" 200 INPUT C'.PRINT 210 PRINT "NHAT IS THE HEIGHT OF THE PILOT"; 220 INPUT H:HUI=N 230 PRINT "HHAT IS THE ARH OF THE PILOT"; 240 INPUT A:A(l)=A:IF C < 2 THEN GOTO 300 250 FOR L=2 TO C:REN LOOP TO GET PASSENGER DATA 260 PRINT "NHAT IS THE NEIBHT OF PASSENGER 'jL-1; 270 INPUT N:N(L]=N 280 PRINT "NHAT IS THE ARH OF PASSENGER ";L-lj 290 INPUT A:A(L)=A:PRINT:N£XT L 300 PRINT "HO* HANY GALLONS OF FUEL ONBOARD"; 310 INPUT F:N!C*!I=F«6:REH 6 LBS/6AL 320 PRINT "NHAT IS THE ARH OF THE FUEL TANK"; 330 INPUT A:A(C»1)=A:PRINT 340 PRINT "HON HANY QUARTS OF OIL ADDED"; 350 INPUT OiN(C+2l=(0»7.5l/4:REH 7.5 LBS/GAL 360 PRINT "NHAT IS THE ARM OF THE OIL"; 370 INPUT A:A(C*2)=A:PRINT 380 PRINT "HON MANY POUNDS OF BAGGAGE AND GEAR";
390 INPUT B:N(C+3)=B 400 PRINT "HHAT IS THE ARN OF THE BAGGAGE"; 410 INPUT A:A(C*3)=A
420 FOR ! = 1 TO (C»!)•.NT=NTiN(I):H(I)=»II)t«(ll:TH=lN»n(l):N£JT I CLSiPRINT "HON RANY I TENS HILL BE ADDED, ROVED, OR CHANGED"; INPUT I:IF Kl THEN GOTO 890 FOR L= 1 TO 1:PRINT PRINT "NHAT IS THE HEIGHT OF 1TEH f;L;
50 MARCH 1985
67O 170 17O 340 20O
ARM
MQMENI
-
50.62 52. OO 52.00 82. OO 95 . 0
1 55O
=
=
33915.4 8840. O 8840.0 27BBO.O 19OOO.O
9B475.4
statements accordingly. At four places in thp program, the expression 'CLS' is used to clear the screen of all printing. Change CLS to the command that your computer will understand. At the end of the routine, the computer will ask if you want to do it again. If you are adjusting equipment or baggage, answer 'Yes' and enter in new weights or arms until
50 PRINT "HHAT IS THE PLANE'S EUPTY HEIGHT"; 40 INPUT PEH:PR1NT
450 460 470 480
£
Aft CG loading: 9B475. 4/1550 = 63.53" Aftmost CG = 61" FIGURE 5
!0 RE!! HEIGHT AND BALANCE PR06&AK BY CHF;1S HURRAY !EAAB9706I 20 BIB A!!OI,!(10),H!10),T»(5!,HllOi,Y$
720 GOTO 760 730 FOR L=l TO I 740 PRINT "ITEH r;L;" 'jHU.ll' 'i«(LI;' ";INT(H(L» 750 NEXT L 760 REH CALCULATE NEH ARH AND C6 770 TH=TNt(PEH«PA):HT=HTtPEH:C6«TH/NT 780 PSINT:PR!NT "PREVIOUS EMPTY HEIGHT = ";PEH; " LBG." 790 IF T*="l" THEN GOTO B20 800 PRINT "LOADED HEIGHT = ";HT;" LBS." 810 PRINT 'GROSS HEIGHT = "iGH;" L8S.":60TO 830 820 PRINT "NEH EHPTY HEIGHT = ";HT;" LBS.1 830 IF NT>6N THEN PRINT •«f»nnnHt««»mi":PRlNT"«*AIRCRAFT LOAD EICEEDS GRO SS NEIBHT«»":PRINT M«mtt«ttmtntftf"
840 PRINT "PREVIOUS HOflENT = ";FEH»PA 850 PRINT "NEN TOTAL HOHENT = "; INTKTNMOO)* .51/100 860 PRINT "PREVIOUS C.G. = 'iPA;" INCHES FROH DATUH' 870 PRINT 'NEN C.G. = "jlNTHCGMOOH .51/100;" INCHES FROB DATUN" 880 IF C6AC6 THEN PRINT ••«tH«t*i««**Hf«*':PRINT "i*CG TRAVEL LIN ITS EXCEEDEDti":PRINT M«»««mHHtt«*" 890 PRINT "DO IT AGAIN (Y/N)1; 900 INPUT Y»:IF YI="N" THEN GOTO 940
910 920 930 940
FOR 1=1 TO 10:A(I)=H(I)=N(l)=0:NEn I A=0:AC6=0:C=0:F=0:FC6=0:BN=0 PA=0:PEH=0:Th=0:H=0:HT=0:60TO 30 END
