Lesson 27: Loading and performance

Welcome back, remote pilots! So far, we’ve  covered almost everything you’d need to know to become a professional pilot. 

Today, we're going to dive deeper into loading and performance, something we briefly explored at the beginning of our course.

Essentially, we’ll learn how the invisible forces of physics work and impact how our drones can fly. 

The Principles of Aerodynamics
Thrust, Drag, Weight, and Lift  

I’m sure many people here have wondered how planes don’t fall from the sky. Today, we’ll answer that question. 

We’ll get into the physics mindset and explore how different factors like aerodynamics, weight, gravity, and weather all help a plane stay up in the air. 

It’s time to explain the Four Principles of Aerodynamics!

Before we fly into the world of physics, let’s quickly define two words that pilots use all the time: level and unaccelerated flight. 

Flying at a level flight means you’re flying
at the same height – and not going up and down!  

And flying in an unaccelerated flight means you’re flying without speeding up or slowing down. Like cruise control on a car! 

When you’re flying in a straight-and-level and unaccelerated flight, there are four invisible forces that impact your drone.

Physicists call these four forces The principles of Aerodynamics, or the study of how air moves stuff around, especially things that fly.

The four principles are:
Lift, drag, thrust, and weight.

Lift is the force pushing the drone upwards. It's what makes the drone move through the air. Drones have motors and propellers that create thrust.

Lift is the force that pushes the drone up into the air. It's the opposite of weight. Drones have wings (or rotors) that create lift. The air flowing over and under the wings generates an upward force, lifting the drone.

Drag is the force that slows an object down. It's caused by air resistance, as the drone moves through the air. 

Drag is the force that tries to slow the drone down. It happens because of the air pushing against the drone as it moves. Pilots and engineers work to minimize drag to make the drone fly more efficiently. You might also see drag described as “friction”.

Thrust is the force pushing the drone forward. It's what makes the drone move through the air. Drones have motors and propellers that create thrust.

And finally, weight is the force of gravity pulling the object down. It must be balanced by lift for an object to stay in the air. 

And finally, weight is the force pulling the drone down toward the Earth. It's like how gravity makes things fall. The weight of the drone depends on how heavy it is.

Awesome! Physics is cool, but what’s loading and performance, and what does physics have to do with today’s lesson?  

The principles → the performance of your drone! 

So, what exactly is loading and performance? Let's break it down.

Hold up – What’s Loading and Performance?  

It’s time to peel the onion! 

So, what exactly is loading and performance? Let's break it down.

Loading is like packing your suitcase for a trip. It means putting people, bags, and fuel on the airplane.

If the airplane is packed too much on one side, it won't fly straight. So, everything needs to be packed just right to keep the airplane balanced.

Performance is about how well the plane flies. If it is too heavy, it needs a longer runway to take off. Also, if it's flying very high or if the weather is hot, the airplane might not fly as well. 

So, how well the airplane performs depends on how it’s packed and the weather.

For drones, loading means all the weight your drone is carrying, including its payload (like cameras and sensors) – plus the weight of the drone itself (like the batteries and parts of its structure).

Loading refers to the weight a drone carries, which includes its payload (like cameras, sensors, and other equipment) and the weight of the drone itself (including batteries and structural parts).

And performance means how well the drone flies and does its job. If the drone is carrying too much weight, it might not fly as high or as fast as it should. It could also run out of battery quickly! 

Ultimately, loading affects the drone’s flight abilities, including stability, maneuverability, and flight duration, and performance is all about how well a drone flies.

“Performance”  encompasses every aspect of a drone’s flight, from the moment it takes off to the moment it lands.

Great work! Before we dive into the details of how physics influences our flights, here’s a helpful, real-life tip.    

There’s something important you should always do when you get a new drone.
What do you think it is?

Every drone comes with a Flight Manual or a Pilot Operating Handbook. Before you fly, you should always read the manual first!

Now, why do you think reading the manual before flying might be important?

Fantastic answers! Another great reason we should read the manual first is that they contain lots of information about the physics / optimal performance of our drone and what it can handle. 

In your manual, you can find information about the 6 different phases of an aircraft’s flight – a path from start to finish: and they are takeoff, climb, range, endurance, descent, and landing.

And knowing all that physics info will help us improve our loading and performance! So let’s talk about each one. 

The 6 Phases of Performance
Take-off, climb, range, endurance, descent, and landing  

Takeoff is when the drone lifts off from the ground or a platform and starts going up into the air.

Climb is the phase where the drone is ascending, increasing altitude, or 'climbing' up into the sky.

Range is the farthest distance a drone can fly away from where it started, while still being able to talk to and be controlled by the person flying it.

Endurance is the amount of time a drone can stay in the air on a single battery charge, before needing to land for recharging.

Descent is when the drone goes down from its flying height to get ready for landing, moving closer to the ground or landing spot.

Landing is the final phase of a drone’s flight, where it touches down on the ground or its designated landing spot.

Wonderful job! Now that we know what all these words mean, you’ll recognize them when you see them in your drone’s manual — remember, you must always read it before your first flight! 

So, how do you think what’s loaded onto your drone affects these phases? For instance, what if your drone’s payload is way too heavy? 

Precisely! If your drone’s payload is too heavy, it can affect how well it can take off, climb, and even maintain a stable flight.

It’s all about balance. 

Did you know that the more a plane weighs, the faster it has to go at a faster speed to maintain its altitude? Otherwise, the plane could fall. 

Heavy payloads can also reduce the range and endurance, meaning it won’t be able to fly as far or as long. 

Weight can also make the descent and landing trickier, potentially causing rough or unsafe landings.

Oops! 

If your drone is too heavy (beyond what the manufacturer says is okay), you can try removing non-essential equipment. 

And, perhaps you remember this from long ago. What’s another reason pilots should care about how much your drone weighs? 

Wonderful. Changing how much your drone weighs can put it in a different category, and each one has its own special rules for flying –
and more dreaded paperwork to fill out. 

We’ll cover paperwork in the next lesson, but know that your drone’s manual will tell you how much weight you can add to it, before it moves into a different category. Handy!

And now, let’s summarize all of the things that can go wrong when your drone weighs too much. 

Bravo, everyone!  So, what happens when a drone is overloaded? Let’s look at 12 things that can happen.

Higher Take-off Speed
The drone would need to go faster to lift off the ground.

Longer take-off run 
The drone would need more runway to take off.

Reduced rate and angle of climb

The drone can’t ascend (get higher) as steeply or as quickly.

The drone would need more runway to take off.

Lower maximum altitude

The drone can’t fly as high. It struggles because of so much weight and sinks down. 

Shorter range

The drone can’t fly as far before needing to refuel or recharge.

Reduced cruising speed 

The drone flies slower when it’s up in the air.

Reduced maneuverability

The drone can’t turn or move as easily.

Higher stalling speed

The drone will stop flying at a higher speed.

Higher approach and landing speed

The drone needs to come in faster to land.

Longer landing roll

The drone needs a longer runway to come to a stop after landing.

Weight on the nosewheel or tailwheel

Too much excessive weight at the front (nose) or back (tail) makes the drone harder to control.

So to recap, when a drone weighs too much, it can impact how high and fast it can go, how quickly it can move, how much battery it takes, and how much space it needs to take-off and land.    

Activity Time
Let’s look at a real drone manual and find information about the drone’s loading limits and performance phases. 

The drone’s manual will also tell you about something super important: the weight and balance (W&B) limitations of your drone. 

Weight and Balance Limitations refer to two key things:

The most weight your drone can carry
How to spread the weight evenly to keep the drone balanced and safe while flying.

Now, even if the flight manual shows a drone’s maximum weight, you still have to worry about other conditions that will affect how your drone can safely take off and land. Oh, my.

But it’s not just about weight! Let’s explore why. 

Remember our good old friend, density altitude?

The higher you go up, and the more humid and hot it is, the air is less dense, and so the density altitude gets lower.    

In thin and less dense air, our drones have to work twice as hard to keep up – there’s not much air to hold onto!

Oh… well, how do we solve this problem? 

Wonderful question! Basically, if you know you’re going to fly in high density altitudes (at higher elevations, or in really humid or hot weather), you simply do this:  

Lighten the load! The payload, that is.  

In other words, you must reduce the weight from your drone, so it’s less than the maximum takeoff weight. 

So in high density altitudes, lighten the load! 

I get weight, but how does high density altitude affect the way drones perform? 

Another great question! This is how high density altitudes affect your drone’s ability to fly. 

Less Lift! At higher density altitudes, the air is thinner, which means your drone's wings can’t  generate as much lift – it’s hard to lift up! 

Less Thrust

Your drone's weight can decrease due to fuel burn or dropping off a package. These changes can directly impact your drone’s performance, so always monitor and adjust for these variations.

Your drone's weight can change during a mission, especially if you’re using it for peculiar things. 

Another thing to consider is that while reading your drone’s manual, you may very well come across the term “Center of Gravity” or CG.

It’s physics time! Let’s explore what the Center of Gravity (CG) is.

Center of Gravity 

Imagine your drone hanging from the ceiling on a string. If it’s perfectly balanced and not tilting at all, it’s hanging from its CG!

But here’s the thing: the CG isn’t always in the same place. What do you think happens if you attach a bigger, heavier camera to your drone?

The Center of Gravity will shift! Even a small change, like adding a heavier camera, can move the CG and impact your drone’s performance.
If your drone’s CG is off, it will be unstable and harder to control.

Less Thrust! Your engine produces less power, making it harder for your drone to climb, accelerate, and carry heavy loads.

A center of gravity is the point in an object where all of its weight is evenly balanced or where it would perfectly balance if suspended. 

🤖 How the FAA Talks 🤖

Compliance with the weight and balance limits of any aircraft is critical to flight safety. Operating above the maximum weight limitation compromises the structural integrity of an aircraft and adversely affects its performance. Operation with the center of gravity (CG) outside the approved limits results in control difficulty.

Maximum altitude: the highest your drone can go  

🤖 How the FAA Talks 🤖 

So, what should you do to keep your drone stable? And… keep the center of gravity? 

To do this, we can follow two steps. 

Keeping the CG within the right limits ensures the drone remains controllable and performs well. 

And you can find those limits in the manual! 

The manual will tell you the CG limits of your drone.

For example, the manual might say “attaching a camera or removing a payload can shift the CG” or “moving the battery to a different position can change the balance.”  

So, reading the manual is like doing homework before flying. It tells you all the things you should and shouldn’t do to your drone. 

The next step is like taking a practice test after doing your homework.

Take your drone out for a spin. Hover your drone in the air for a few seconds, to make sure it’s stable before starting your mission. 

If it flies lopsided, the CG is off and not balanced. 

Great work! I see you’re all a few steps closer to becoming a certified drone pilot.