All posts tagged 'Flying'

How CG Location Can Affect Airplane Performance

Hey everyone! I hope you all have had a good start to 2020, stuck to your resolutions, and greased all your landings so far. I heard a pretty good joke the other day that I wanted to share at the start of this post before we dig into some CG topics.

So we all know about Murphy's law right? It's very prevalent in aviation: anything that can go wrong will go wrong.

Well, here's how to get your friends on a good joke. 

"So you've heard of Murphy's law right?"

"Yes"

"Well have you heard of Cole's Law?"

"No what's that?"

"Oh it's just sliced cabbage with some dressing."

Love it! So cheesy but it's funny.

Ok now let's dig into some topics of the center of gravity.

First off: What is it? Well according to the Pilot's Handbook of Aeronautical Knowledge it is "the point at which an airplane would balance if it were possible to suspend it at that point."

Think about when you would get bored in elementary school and try to balance a pencil on your finger. Remember when you'd finally get it balanced, but it had to be a specific spot on the pencil or it'd fall back off? That's exactly what CG is on a plane. It's where most of the weight is concentrated, so once we load up the plane if it's within the CG then it flies the most stable and safe. It's also important to note that a CG is not just a fixed a point but it can move depending on the distribution of weight throughout the plane. 

But let's say we loaded the plane with too much weight or we didn't distribute it well and now we're out of CG limits. We can either be forward or aft (behind) that area. 

Forward Characteristics:

-Nose heavy

-Difficult to impossible to lift nose for takeoff

-Better stall recovery

-Total lift required by the wing is increased

-Wing flies at higher angle of attack, resulting in higher drag and higher indicated stall speed

Aft Characteristics:

-Tail heavy

-Difficult to impossible to recover from a stall

-Violent stall characteristics

-Light control forces that make it easy to overstress the plane

-Wing flies at lower angle of attack, resulting in lower drag and higher cruise speed

It's also always important to ensure to not take off past the max takeoff weight, and if you do it's brought down quickly/easily due to fuel burn. The effects of being overweight are dangerous. It includes:

-Higher takeoff speed

-Longer ground roll on takeoff and landing

-Higher stalling speed

-Reduced climb rate

-Excessive weight on the landing gear that can cause a collapse

-Accelerating metal fatigue over time

These characteristics run for all planes too, whether you're flying a Cirrus SR-22 or a King Air A100 you never want to be overweight or out of CG.

When it comes to weight and balance there is also several important terms to know that we use in order to help us calculate properly. These include:

Arm: horizontal distance from the datum line to the CG of an item (measured in inches)

Datum: an imaginary line from which all horizontal distances are measured in order to balance the aircraft. This is picked by the manufacturer and is usually somewhere like in front of the engine firewall or the leading edge of the wing. 

Basic Empty Weight: the standard empty weight of the plane and any optional equipment installed

Standard Empty Weight: the weight of the airframe, engines, permanently installed items in the airplane, unusable fuel, full operating fluids and oil.

Moment: this is the product of weight x arm and is considered to be the force that causes an object to rotate.

If you're ever trying to remember these and study some more check out chapter 10 of the Pilot's Handbook of Aeronautical Knowledge and your own operating handbook for whichever plane you're flying. There's always so much to talk about with weight and balance but if you remember anything know this: don't ever land overweight and never accept an aft CG! That's the two most dangerous scenarios. 

Anything else to add about weight and balance? Drop it below!

Initial Radio Calls for Beginners

Have you been working on radio calls lately and struggling to get them down?

Let's talk about how to at least make your initial call and go from there.

Ok so here's the scenario: you're sitting at a towered airport and completed all your checklists that were called for so now you're ready for taxi. Your hand goes to the PTT (push to talk) and your mind goes blank. What do you say?

This is the format to use on the ground:

-Who you're talking to

-Who you are

-Where you are

-What you want

So let's say this towered airport is KEFD (Ellington Field), your plane is a Grumman Tiger N9696W (this is just a fictional tail number I created), and you're in front of the FBO Signature there waiting to go on your flight to KACT to Waco. Using all of that information as well as knowing they have an ATIS there you need to listen to for information, let's put it together for a radio call.

"Ellington ground, Grumman 9696W at Signature, ready to taxi with information Papa"

Some people can argue you don't need to say direction of flight on the ground, only after you switch to tower, but I sometimes let ground AND tower know. I simply do this because often when I call ground at a towered airport, if I don't say it they come back with "say direction of flight." So here it's your preference, given that at the minimum you let tower know which direction you're headed.

Okay now let's say it's the same situation except you're at an uncontrolled airport T41 making an announcement call. This sounds almost the exact same (using the same format still) but you start AND end the radio call with who you're talking to. Remember at uncontrolled as well you're not asking for clearance, so you're only announcing what you're about to do.

Assuming there is a Signature there as well (though in reality there is not) and we want to taxi to runway 12 via Alpha here's what this radio call would sound like:

"La Porte traffic, Grumman 9696W at Signature taxiing to 12 via Alpha, La Porte traffic"

The call for takeoff would sound the same, except then we'd be announcing which direction we'll be departing to to let other traffic know. If we're going to Waco from T41, the direction is to the northwest. Here's what that would sound like:

"La Porte traffic, Grumman 9696W taking the active 12, departing to the northwest, La Porte traffic"

Still generally the same format as we first talked about. Just to keep elaborating, if I'm now holding short of 17R on Bravo at Ellington and ready to takeoff here's my call to tower:

"Ellington tower, Grumman 9696W holding short of 17R on Bravo, ready for departure VFR to Waco"

You notice how in every call they're all similar? The format may change in some calls as you'll learn the more you practice using radios, but this is always the basis most of them follow. 

There comes the subject of after making your initial call what to repeat back at a towered airport and what you don't need to repeat back, or in uncontrolled airspace how to communicate well with other pilots. There's a lot more that can be talked about with radio calls, so we'll likely talk about them another day. 

I hope everyone has a Happy New Year, stays safe, and sounds like a pro on the radios now!

Questions or comments concerning radio calls? Let us know below!

Happy Landings,

-Addi

 

Tips for Noting the Wind on Ground Reference Maneuvers

Here's a short scenario:

You've just taken off from your home airport. You fly about 25 nautical miles out from where you took off and go find an area to do ground reference maneuvers.

Once you find an area you like you begin to get yourself set up to do your first maneuver: rectangular course for example. For rectangular course you have to enter it with a tailwind just like you would enter a typical traffic pattern. So now it's time to note the wind.

First rule: don't just use the direction the winds were at back at your home airport.

But it's just 25nm away, they should be the same right?

Wrong!

The winds can actually be blowing a completely opposite direction than they were back at the airport. This can be due to surface friction, the terrain of the area you're in, and of course what the weather is like for the day. If one area has thunderstorms blowing in the winds can be gusty and shifting, while 20nm away they're calm and skies are clear.

Remember this, especially on a check ride, when it comes to noting the winds. 

So, if you're just over an area with a bunch of fields and no airport to report the weather how do you find the wind direction?

Very simply: look outside.

Now, obviously you cannot truly see wind. But, you can see objects that it's blowing and the direction they're facing.

A great example would be the references that I use since I fly in Houston: refineries. The stacks are almost always blowing steam from the top and it's very easy just to glance at them and see which way the wind is blowing it.

Some other outside visual references would be trees, water, smoke if there is any fires out etc.

If there isn't any references to use and you have an avionics system on board, bring up the groundspeed display. You can always look at this and fly a 360 degree turn to set up for the maneuver and check where you groundspeed is fastest and where it is slowest.

This will tell you exactly where your tailwind is and where you have a headwind, so you can calculate from there how to enter the maneuver.

Using groundspeed also tells you a rough estimate of how strong the wind is blowing, so you can have an idea of how much correction you'll need during the ground reference maneuvers to hold your track. The bigger a difference between your slowest and fastest groundspeeds, the stronger the wind likely is.

Have any other tips you've found for your maneuvers? Drop them below!

We hope you're getting in the Christmas spirit this month, head over to Globalair.com to check out our cool Santa hat on the logo and see what's available on our website!

 

How to Determine Your Pivotal Altitude

Whether you're working on your commercial certificate now, going to be, or already have then you'll find this useful.

As part of the Commercial ACS, we as pilots have to learn Eight's-on-Pylons. This is a maneuver in which the plane flies around two pylons maintaining a visual sight reference with each one in relation to the lateral axis of the airplane. Drawing the plane's ground track, it looks like a figure 8, thus the term Eight's-on-Pylons. 

Picture from the Airplane Flying Handbook

One of the most important concepts to take from this maneuver is pivotal altitude.

So what is it?

Pivotal altitude is the altitude at which, for a given groundspeed, the projection of the visual reference line to the pylon appears to pivot. Simply put, it's what the plane keeps coming back to each time you're able to maintain the pylon off the wingtip and hold it. 

This is also something that is calculated before the maneuver is begun using the airplane's groundspeed. It's the groundspeed squared divided by either 15 for miles per hour or 11.3 for knots. 

Some things to note about pivotal altitude is it does not change with the angle of bank, given that it is not steep enough to affect the groundspeed (but if you do the maneuver and correct for wind properly you shouldn't have to over-steepen the bank where this happens). 

Pivotal altitude can be noted very easily while flying around the pylons. All you have to do is get the plane stabilized where you're holding the pylon off the wingtip with no pitch up or down correction, then look at your altimeter and note the altitude! This is what the plane will keep coming back to. 

You should also enter and exit the maneuver at the pivotal altitude; how close or far you are from it when exiting can exhibit how well the maneuver was performed. 

If you're needing help with commercial maneuvers, or just want to pursue a commercial certificate, take a look at our Aviation Training Directory to find somewhere near you to train.

Best of luck with your Eight's-on-Pylons and happy landings!

-Addi

 

Understanding the Fundamentals of Instructing

Picture this: it's your first flight lesson ever. You walk into your brand new flight school, in which you've never flown their planes before, and have yet to meet anyone you know there. This is all fresh to you. Do you think your first flight lesson will be highly productive, or will produce somewhat of a challenge?

The answer is, according to Maslow's hierarchy of needs, that you will not learn as much as if you felt comfortable in your new school. This is the belonging hierarchy. Once you get settled in, learn their fleet, make some friends and are known by the people there then you'll start to unconsciously progress better with each lesson.

Factors such as this are what makes up what is referred to as Fundamentals of Instructing, or FOI's. 

FOI's are important to the instructor in flight training as well as to the student because it defines concepts like human behavior & how we acquire knowledge; why we act the way we do and how we learn. 

Let's discuss some important topics of FOI's that are commonly seen as well as discussed on a flight instructor check ride:

1) Human Needs That Must Be Met to Encourage Learning

Physiological: Biological needs such as water, air, sleep and shelter. It's easier to focus and grasp something when you've eaten and are properly hydrated compared to when you're not.

Security: Feeling safe and secure in the environment around you

Belonging: Just as previously discussed, feeling wanted and including

Esteem: Have you ever heard of a lesson where your instructor refers to it as confidence building? Self confidence is important in flying

Cognitive & Aesthetic: This is connected to when we as humans like or don't like something. We'll learn more from a teacher that we like than one we don't.

Self-Actualization: I like to think of this as knowing where you're at and where you're going. Helping a student achieve their potential is an important job of a flight instructor.

2) Defense Mechanisms

Repression, Denial, Compensation, Projection, Rationalization, Reaction Formation, Fantasy, and Displacement

These are important to recognize because they're excuses (so to speak) that people use when they have a bad experience to protect their ego. One of the most common exhibited by students in flight training is reaction formation; faking a belief opposite to the true belief because it causes anxiety. For example, pretending they don't care how their lesson went after a bad day when in reality it bothers them. These can all be found in more detail in the Aviation Instructor's Handbook chapter 1.

3) Types of Practice

Skipping ahead to chapter 3, there are types of practice instructor's can use to help a student learn a skill. These are:

Deliberate: Aiming a practice at a deliberate goal, such as specifically focusing on slow fight during one lesson. The student and instructor have set a goal to accomplish something before beginning the lesson.

Blocked: This is doing the same drill until the movement becomes automatic, also known as creating a muscle memory. Blocked practice can be seen most often during landings, as the instructor has the student memorize a before landing checklist. The student configures the plane on downwind (mixture full rich, carb heat, gear down etc) then can go to the checklist to ensure they did not forget an item. 

Random: Random practice is mixing up skills, for example going out and giving the student maneuvers to perform randomly so it tests how well they understand and can perform it consistently. 

There are MANY many concepts to learn about when studying FOI's. These are just 3 that will likely be brought up by an examiner, however they will cover much much more. 

The Aviation Instructor's Handbook as well as the Flight Instructor Oral Exam Guide published by ASA are good materials to use when preparing for a CFI check ride. 

After you finish reading about FOI's, go check out some more articles full of aviation information published by Globalair.com as well as reading articles written by our 2019-2020 scholarship recipients! 

Questions are comments about FOI's? Comment below

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