MAKING TAKEOFFS

[Tom Goodrick]

You might think you can just make a takeoff by getting the plane going fast enough and jerking back on the stick. That may do it but you will display no class. The trick is to lift off smoothly so that the plane continues to climb smoothly without dipping. Some tips that will help you look like a pro are given below.

We will discuss takeoffs in general with more attention toward the single engine aircraft. In a single, when the one and only engine quits, you will land the plane, period. No "if's ands or buts." Maintain flying airspeed and steer to miss the hard stuff.

Before starting the engine, make sure the fuel amount is correct for the flight. It should allow you to get to the destination with at least 45 minutes of flying time left. Of course this implies some flight planning. In most aircraft you don't jump in and get airbourn and then decide where to go. You need a flight plan. An additional aspect in figuring the amount of fuel is the required maximum landing weight for many aircraft. This present a problem with short flights. You cannot "tanker" the fuel or carry more than you need because it will leave you too heavy to land. The max landing weight assures that the landding gear can handle the stresses of landing. In FS9, we design the gear parameters to handle the max landing weight. If heavier than this you will have problems and may crash, as in real life.

Before beginning the takeoff, it is important to check several things. First, make sure the altimeter shows the proper value (the elevation of the field). Tap B if in doubt. Next make sure you are looking at Indicated Airspeed. That is the only airspeed to look at when flying the aircraft. It will guarantee you won't stall (if you stay above the stall speed) regardless of altitude. Note that FS9 incorrectly give the airspeed (in the aircraft.cfg file) in KTAS - true airspeed. That should be KIAS for Indicated Airspeed.
Next, make sure the autopilot it OFF. Set trim as mentioned below. Finally look through the windshield at how the runway edges intersect the sides of the windshield. That is close to the view you want when you land. (Actually, a little more nose up than that.) You'll see the best view momentarily before lift off.

Twin engine aircraft have a minimum control airspeed, called VMC, which is the lowest airspeed at which control can be maintained with one engine at full power and the other at reduced or zero power. A pilot of a twin must stay low over the runway until reaching that speed.

All aircraft will hold a particular airspeed in any aspect of unaccelerated flight when the pitch trim is set at a particular value and the stick is relaxed. There is a particular trim setting desired for takeoff. It is best to set that trim value. I always use a digital trim indicator so I can set particular values as noted in the checklist for takeoff. Then during the takeoff, I hold a slight forward pressure on the stick to keep the plane from flying off before I am ready for it to fly. If the wind is gusty I'll keep it on a little longer. Then by simply releasing the pressure on the stick smoothly, the aircraft will rotate a little and fly away at a good angle and maintaining the proper airspeed.

When I said the aircraft holds a constant airspeed for a constant trim setting, I fibbed a little. What I mean is there is one airspeed value at which the forces balance for a given trim setting. But if the forces are out of balance, there will be an oscillation called a "phugoid" that will take place for a few minutes as the airspeed and the vertical speed change out of phase until the forces begin to balance. At altitude that is a very minor annoyance. But within a 100 feet of the ground it can kill you.

Get either the Cessna 172 or 182 in the air with one of my digital trim gauges on the panel and get it into steady level flight at 75 or 80 KIAS respectively (75 for the 172, etc). Use the autopilot to assure very steady flight. Jot down that trim setting. Now go back and do a takeoff with that same exact trim setting. As the aircraft rotates you may have to fight the phugoid a little bit to get it climging steadily. Use full power. You should be able to remove all displacement or pressure from the stick while the steady climb continues. After making sure the aircraft is climbing steadily, reduce power with no change in the stick setting. Watch the airspeed and attitude. It should transition smoothly to climb at a lower rate or even fly level. Find the power setting that keeps it flying level.

If you drop the power completely shortly after takeoff, you may find the plane noses down extremely and dives a bit as it starts a phugoid. You must move the stick forward and back enough to reduce the severity of that initial dive. Then let the aircraft glide, find a spot and land it. Doing takeoffs from a 10,000 ft runway in a Cessna is not realistic. Most Cessna's take off from runways between 2000 ft and 3000 ft long so you are past the end when power is lost. Do several takeoffs and cut power at various stages in the climb out to get used to the idea that you can handle a loss of power after takeoff. The sim will tell you if you have crashed.

Next reduce the Reliability of the engine and make more takeoffs followed by a climb to a reasonable altitude for cruise.

It is actually possible to fly an airplane through a takeoff, climb, cruise and landing using just the throttle for pitch control. Smooth power changes can avoid or reduce the severity of phugoids. When you line up with the runway, reduction of power will give you a safe final approach. Add a little power to flare gently for touchdown. This is good opractice to wean yourself off the stick. Many people think the plane cannot fly without good stick work. Actually, the stick and pitch trim do nothing but set arispeed and damp phugoids. The throttle determines whether the plane climbs or descends.

[Allan_Lowson]

Perfect choice for a launch topic for the new forum, Tom!

[Tom Goodrick]

This was mostly copied from the other forum. But I overlooked a couple of issues: tailwheel takeoffs and V speeds.

With tailwheel aircraft, you begin the roll holding the stick back. You don't want it to fly until you are ready. At about 30 KIAS you push the stick forward a bit until you raise the tailwheel gently. Then the rest of the takeoff is the same as in a nosewheel aircraft.

In more complex aircraft, especially turboprops and jets, Vspeeds determine what you do during takeoff. As mentioned above, VMC is used in a twin to determine when to lift off with full directional control even if one engine quits. other Vspeeds are used on takeoff. V1 is the decision speed. Below that speed, you can stop on the runway. After that speed you are committed to flight. This depends on aircraft weight, on airport elevation and on runway length. Normally there are charts in the Pilots' Operating Manual that show you how to figure this speed. Regulations require that commercial pilots determine V1 for each takeoff.

VR and V2 are the airspeeds for rotation and for safe takeoff speed. You rotate at VR and then you lift off at V2. I have developed a gauge that shows V2 for each takeoff based on aircraft weight. This value is 1.3 times the stall speed for the aircraft weight. It is displayed digitally next to the digital airspeed indication in the PFD (Primary Flight Data display). I recommend that you make VR 10 knots below V2. The takeoff at that point is highly dynamic and you can't be doing fancy arithmetic. 10 knots below V2 works because you will actually lift off a little above V2 in most case. All V speeds are in KIAS. V1 is determined based on elevation because it relates to ground-based momentum. VR and V2 work regardless of elevation as they are keyed to the stall speed.

If you download a V2 gauge from my web site (on an existing panel), make sure it was developed for your aircraft. It can be used with a different panel if you prefer. The name of the aircraft is included in the name of the gauge.

[Tom Goodrick]

This deals with AIRSPEED and STALLS.

There are several types of airspeed. We should mention them because you will find them used in aviation books and magazines. Indeed it can be very confusing for anyone. Stall speed is very important to know. When you get checked out in an aircraft you have not flown before (in real life), you buy or borrow the Pilots' Operating Handbook (POH) for that plane and study it before showing up for the checkout. One of the most important things they tell you is the stall speed. This is given for the plane at gross weight with power off. When I transitioned to the Cessna 172, I bought the manual and still have it. It says the stall speed with flaps up and zero bank is 57 mph cas. (That was an old plane and old book when we still used miles per hour instead of knots.) So what is CAS? It is Calibrated Airspeed.) Fortunately, on the same page of the manual there is a calibration chart that shows 58 CAS equals 50 IAS. So that told me that 50 IAS (43.5 KIAS) can be used as the stall speed with flaps up at zero bank. (It is a little high but that is okay. You can use a speed higher than the actual stall speed because you will endeavor to fly the plane always at higher speeds.)

The trouble is that in the cockpit you only see IAS, not CAS. If you start getting slow you have no time to consult a table in a book. The calibration is highly non-linear. At 50 IAS the difference is 8 mph. At 60 IAS the difference is 5 mph. At 70 IAS and above it is only 2 mph until 110 IAS where there is no difference. Indeed, the stall speed in a 40 degree bank is 65 CAS which is 60 IAS. In a 60 degree bank the stall speed is 81 CAS which is 79 IAS. The difference is in the way in which air flows near the pitot tube that measures the airspeed. Ideally, the pitot tube would be on a long probe extending well in front of the aircraft. You see such probes on aircraft that are undergoing developmental testing. They would be rather impractical on an airport parking ramp. So today if you look at the specs listed for an aircraft in a magazine, you will often see "60 KCAS" or 60 knots CAS. But you don't know what the calibration table looks like so you don't know what the KIAS value would be at stall. That is unfortunate. In FS we develop the aircraft so it stalls somewhere near that KCAS value as though it were a KIAS value. There is a standard calibration equation but it is linear and should never be used because it is pure poppycock.

The bottom line is to use the KIAS stall speed as a guide. The reference material and/or checklist for any FS airplane should tell you the stall speed. Because it is given always for gross weight, the actual weight you will fly will generally be lower and the corresponding stall speed will be lower. But by assumming stall will occur at the higher speed, you are safe.

Stall really occurs at a particular angle of attack at which the lift can barely hold up the aircraft. When airspeed drops slightly below the stall value, the wing lift drops very significantly and the aircraft begins falling. It will not resume flight until you get the nose closer in line with its path through the air, reducing the angle of attack. Your survival depends on having enough altitude to allow you to transition to level flight when you get the plane flying.

When the plane is flown with a normal 1G acceleration - just countering the downward acceleration of gravity, there is a direct correspondence between the indicated airspeed and the angle of attack. But when the plane is accelerated as in a bank where only part of the lift can support the aircraft, more than 1G must be maintained to keep the plane turning along a level path. This is why the stall speed will increase in a bank.

At 15 degrees bank, stall speed increases by 1.75% over level stall speed.
At 30 degrees bank, stall speed increases by 7.46%.
At 45 degrees bank, stall speed increases by 18.92%.
At 60 degrees bank, stall speed increases by 41.42% over level stall speed..

It becomes obvious why turns at low altitude near the airport should be kept to 15 degrees bank in instrument conditions and why any bank over 60 degrees is considered aerobatic flight.

Now another dragon rears its head to smoke the poor uneducated pilot. We said the relation between airspeed and angle of attack holds true only in normal 1G flight. What if you takeoff, level off and then pull into a climb as you roll into a bank? You can expect to encounter an accelerated stall which can be a doozy, flipping you inverted before you can say something like "Oh, Golly!" The result is often fatal.

The first turn after takeoff is usually made at 400 feet above runway elevation. If you pull back hard on the stick as you roll into that turn, you will probably encounter an embarrassing situation. Try it in FS but not in real life. As you float into the After-life, you will say "But I was well above the stall speed!"