Designing a Model Aircraft: Calculating Thrust and Lift for an Efficient Flight

In summary: ever...) but I'm just a high school student, so a lot of this stuff is new to me. Thank you for the book suggestions, I'll give those a look over. I don't want it to come across as me underestimating the scope of the project or anything like that (nobody...ever...) but I'm just a high school student, so a lot of this stuff is new to me.
  • #1
TheArrow
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TL;DR Summary
Planning to build a model aircraft, looking for feedback
Hello Everyone,

I'm planning on designing a model aircraft that would be powered by an Arduino and electric motor. I'm interested in pursuing an aerospace degree and I figured the best way to get a headstart would be be to dive right into a project. This is also probably overthinking/overdoing it, but I want to get in the mindset of "thinking" like an engineer.

Thinking aloud, if anyone actually knows what they're doing, by all means correct me or give ideas:
  1. Since I have a payload in mind (i.e. the Arduino board, the power supply, servos, etc.), I have to ballpark how much thrust the prop will need to generate to move the aircraft. From playing around with the industry standard design simulator, Kerbal Space Program, I'm looking at this similarly to Delta-V. A rocket needs to provide sufficient Delta-V to lift the payload and the mass of the rocket to fulfill whatever mission objectives are laid out for the payload.
  2. Design an airframe around the motor and other components with sufficient lift to make the plane do plane things.
  3. Design a controller to do pilot things.
So for Step 1, I was wondering how I would go about computing how much thrust would be required so I can select an appropriate prop/motor combination.

For Step 2, a question that comes to mind off the top of my head would be whether the bottom of the fuselage counts as a lift surface when doing calculations pertaining to surface area (assuming this will be a cantilever wing monoplane design). So the bottom of the wing will be flush with the bottom of the fuselage.

Anyways, that's all I have for now. I'll update this thread with progress as I go along.
 
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  • #2
You're talking about a fixed-wing airplane, right? Have you looked into what hobby kits are available, and how they are designed? For your first, maybe it would be better to build an already designed airplane and learn from its design? Making an autonomous airplane is not a small task.
 
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  • #3
russ_watters said:
You're talking about a fixed-wing airplane, right? Have you looked into what hobby kits are available, and how they are designed? For your first, maybe it would be better to build an already designed airplane and learn from its design? Making an autonomous airplane is not a small task.

I've built static model airplanes before. But I haven't ventured into the RC field. The kits that I've seen are a bit out of my price range (being unable to work at my usual job because of the Rona) at the moment. For the most part this was lending itself more towards a FreeCAD design exercise that could eventually lead to putting together a physical model in the future. And yes, a fixed wing design.
 
  • #4
TheArrow said:
I want to get in the mindset of "thinking" like an engineer.
An engineer starts by doing some research on the scope of the project. The suggestions by @russ_watters are an excellent place to start. Have you considered getting a model glider (3' to 4' wingspan) and adding the Arduino? Less cost than a powered model, and the control challenges would be the same. An RC model will have power supply, servos, servo wiring, and servo linkages all properly sized, connected, and working. You could replace the controller with your Arduino.

If you really want to design your own model airplane, get a book such as Aerodynamics, Aeronautics, and Flight Mechanics by McCormick. That's not the only book out there, but the first edition has 652 pages of everything you need to know about lift, drag, power, and controllability. Especially controllability.

For structural design, Aircraft Structures by Peery covers aluminum construction very well. I do not have a good recommendation for the wood and/or fiber reinforced composite construction used by model airplanes.

I once had the idea of designing and building my own real airplane, so I bought and read the above books. And I bought a 1946 Taylorcraft BC-12D for a rebuild project to learn the practical aspects. All of that convinced me to do something else.
 
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  • #5
jrmichler said:
If you really want to design your own model airplane, get a book such as Aerodynamics, Aeronautics, and Flight Mechanics by McCormick. That's not the only book out there, but the first edition has 652 pages of everything you need to know about lift, drag, power, and controllability. Especially controllability.

For structural design, Aircraft Structures by Peery covers aluminum construction very well. I do not have a good recommendation for the wood and/or fiber reinforced composite construction used by model airplanes.

Thank you for the book suggestions, I'll give those a look over. I don't want it to come across as me underestimating the scope of the project or anything like that (nobody should underestimate the challenging job engineers have). For me, it's more about stumbling into problems naturally and then looking for solutions for those problems. It's not entirely about completing the project and having a physical little plane zooming around. It's more so exploring and stumbling on purpose. But I will look into a little glider model in addition to your book suggestions. Thank you so much for your informative reply!
 
  • #6
TheArrow said:
It's not entirely about completing the project and having a physical little plane zooming around.
Any experimental electric powered model will benefit from good glide characteristics. Buy a kit or a set of plans, then build an RC model glider. That way you get the quick reward and some experience soaring.
Then fit the battery, control system and motor once you know what your powered launch requirements are. Consider a pusher prop that will be less susceptible to damage when landing.
With GPS on a glider, it should be possible to autonomously map the rising air as it flows over a hill, or in a thermal.
Glider pilots are aware of the ground conditions and the flow of air around them, so they can avoid getting into trouble in the first place. They understand the range of forces on the aircraft.
 
  • #7
Baluncore said:
Any experimental electric powered model will benefit from good glide characteristics. Buy a kit or a set of plans, then build an RC model glider. That way you get the quick reward and some experience soaring.
Then fit the battery, control system and motor once you know what your powered launch requirements are. Consider a pusher prop that will be less susceptible to damage when landing.
With GPS on a glider, it should be possible to autonomously map the rising air as it flows over a hill, or in a thermal.
Glider pilots are aware of the ground conditions and the flow of air around them, so they can avoid getting into trouble in the first place. They understand the range of forces on the aircraft.

After all these replies, I'm definitely going to find to a cheap glider model and play around with it while I work through the books that were suggested to better understand what's going on. I've flown myself for hundreds of hours in flight simulators but also in real life as a student pilot in powered aircraft. So I have an intuitive understanding of how forces of flight work, but not necessarily a quantitative or analytical sense for the exact relationship those forces have with each other. But the book by McCormick is exactly what I'm looking for with that.
 
  • #8
Google Ardupilot. Starting from scratch if you have no experience and financial means sounds to me like a way to fail.

There are several RC DIY model/plane/whatever forums, where you will easily get help from people doing these things (designing models, tinkering with autopilots) and having a lot of experience. They will probably guide you to some sets of approximate rules they use for any more or less typical model, I remember reading them collected somewhere on a web.
 
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  • #10
Borek said:
Google Ardupilot. Starting from scratch if you have no experience and financial means sounds to me like a way to fail.

Thanks I'll take a look into Ardupilot.

My recommendations:

Thank you for the resources!
 
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1. How do I choose the right materials for my model aircraft?

Choosing the right materials for your model aircraft depends on several factors, such as the type of aircraft, its intended use, and your budget. Generally, lightweight materials like balsa wood, foam, and carbon fiber are popular choices for model aircraft. It's important to consider the weight, strength, and durability of the materials when making your decision.

2. What is the best design for a model aircraft?

The best design for a model aircraft varies depending on its purpose. Some popular designs include gliders, trainers, and scale models. It's important to consider factors like stability, aerodynamics, and structural integrity when choosing a design. You can also find inspiration from existing aircraft or experiment with your own unique design.

3. How do I ensure the balance and stability of my model aircraft?

Balance and stability are crucial for the successful flight of a model aircraft. To achieve this, make sure the weight is evenly distributed and the center of gravity is in the correct position. You can also use a flight simulator or conduct test flights to fine-tune the balance and stability of your aircraft.

4. What tools and equipment do I need for building a model aircraft?

The tools and equipment you need for building a model aircraft will depend on the complexity of your design. However, some essential tools include a hobby knife, sandpaper, glue, and a cutting mat. You may also need specialized tools like a heat gun or soldering iron for more advanced designs.

5. How can I make my model aircraft fly longer and higher?

To make your model aircraft fly longer and higher, you can make adjustments to its design and weight distribution. For example, reducing the weight by using lighter materials or adding wingspan can improve its flight capabilities. You can also experiment with different propulsion systems, such as rubber bands or electric motors, to increase the power and flight time of your aircraft.

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