Optimizing for Weight in Ultralight Aircraft Builds

Table of Contents

The ultralight aircraft industry is a rapidly growing market with the increasing popularity of ultralight drones and other UAVs (unmanned aerial vehicles). In recent years, these technologies have been found in markets of all sizes ranging from uses in the arenas of civil, commercial, and military, as well as hobbyist and recreational areas. 

As a material supplier and specialist in a variety of fabrication services, we at SendCutSend can offer valuable guidance, materials, and services to prospective ultralight UAV builders looking to enter this rapidly growing industry. 

In this article we will explore one of the most critical things in the design of ultralight aircraft— materials used for optimizing weight in ultralight UAV structures. 

Design

To give context to the importance of material selection when it comes to the mechanical structure of ultralight aircraft, let’s take a look at the basic and general components found on ultralight aircrafts. In a typical ultralight aircraft or UAV, the primary components consist of (but are not limited to) the following.

  • Frame: The frame serves as the structure that holds all the components together. It can be made of lightweight materials such as composites, plastic, or light metals.
  • Propulsion System: This includes motors and propellers. Electric motors are commonly used in UAVs, and they provide the necessary thrust to lift the drone off the ground and maneuver it in the air.
  • Battery: Drones are powered by rechargeable batteries.
  • Electronic Speed Controllers: Speed controllers regulate the speed of the motors by controlling the power supplied to them. They receive commands from the flight controller and adjust the motor speeds accordingly.
  • Radio Transmitter and Receiver: These components enable communication between the drone and the ground control station or remote controller. The transmitter is operated by the pilot, while the receiver is installed on the drone to receive commands and relay data back to the pilot.
  • Sensors: Drones may be equipped with other sensors such as GPS for navigation, barometers for altitude sensing, and cameras for capturing images or videos.
  • Payload: Depending on the intended application, drones may carry various payloads such as cameras, sensors, packages for delivery, or other specialized equipment.
  • Safety Features: These may include features like fail-safes (e.g., return-to-home function), obstacle avoidance sensors, and propeller guards to enhance safety during operation.

These components work together to enable the drone to perform its intended tasks efficiently and safely. The specific configuration and features may vary depending on the drone’s size, purpose, and complexity. From the list of components, a clear observation can be made that a critical piece of the aircraft is the frame and brackets used to mount smaller items to the frame. Therefore, materials that have high strength and stiffness are extremely important in the design of aircraft structures in order to ensure rigid mounting and reliability. 

However, due to the requirement for the aircraft propulsion system (motors and propellers) to be able to overcome the force of gravity, it is also critical for these components to be lightweight. 

Therefore, a careful consideration of material choice is extremely important, as it relates to structural components. 

In the end, material choice will always be heavily interdependent with other important factors such as the intended motor power and strength requirements required for durability and end use cases. Nevertheless, general knowledge of the benefits, material properties, and characteristics of common materials is valuable in making material choice decisions to optimize weight for strong but lightweight aircraft. Let’s dive deeper into that.

Materials

Strong sheet metal materials — such as Aluminum, steel, titanium, and composite materials — are commonly used materials in the design of lightweight aircraft structures. Important considerations to make are their weight, structural properties and durability, performance, maintenance, and cost. 

Aluminum

Aluminum is favored in aerial drone design, offering both strength and lightweight properties crucial for flight efficiency. Although not as strong as steel or titanium, its structural integrity still allows for sturdy frames capable of withstanding the stresses of flight maneuvers while maintaining a lighter weight than steel or titanium. Aluminum’s performance in drone applications is notable for its ability to endure various environmental conditions and impacts. 

Maintenance requirements are typically low due to aluminum’s resistance to corrosion, reducing the need for frequent repairs or replacements. While aluminum is generally more affordable compared to other lightweight materials like carbon fiber, its cost may still vary depending on the grade and specifications required for specific drone designs. 

Overall, aluminum stands as a cost-effective and reliable choice for drone construction, contributing to the widespread adoption of this material in the UAV industry. At SendCutSend we offer 2024, 5052, 6061, 7075 Aluminum alloys in a variety of thicknesses.

Steel

Steel, though denser than aluminum, offers exceptional structural properties suitable for aerial drone design, particularly in larger or industrial-grade drones where durability is paramount. Its high tensile strength and rigidity ensure stability and resistance to deformation during flight, making it a preferred choice for heavy-duty applications or situations where drones may encounter significant stress. While steel’s density may slightly compromise overall flight efficiency, its robustness enhances performance in harsh environments or high-load scenarios. 

Maintenance requirements are generally low due to steel’s corrosion resistance and longevity if using alloy steels that are corrosion resistant. This reduces the need for frequent repairs or replacements. However, steel’s heavier weight may impact flight endurance and maneuverability, and its cost can be higher compared to aluminum, especially in customized or specialty grades or alloys. 

Nonetheless, for specific drone designs prioritizing strength and resilience, steel remains a reliable material choice in aerial UAV construction. SendCutSend’s catalog of steel materials ranges from AR400 and AR500 to 1075 Blue Temper Spring Steel, G90, Mild Steel, and Stainless Steel

Titanium

Titanium boasts a remarkable strength-to-weight ratio, making it an ideal choice for aerial drone design where both durability and lightweight construction are crucial. While still heavier than aluminum, it has lower weight but similar strength as steel, ensuring a superior strength to weight ratio. 

Titanium’s good corrosion resistance also ensures longevity and reduces maintenance needs, particularly in harsh environments. However, its high material and manufacturing costs may limit its widespread use, typically reserved for specialized or high-performance drone applications where its unique properties justify the investment. 

Overall, titanium offers unparalleled strength to weight ratio with reliability, albeit at a premium price. Therefore, it is a preferred material for cutting-edge aerial drone designs demanding the utmost in performance and durability. SendCutSend currently offers Grade 2 Titanium and Grade 5 Titanium in multiple thicknesses. 

Composite Materials

Composite materials, such as carbon fiber reinforced polymers (CFRP) or fiberglass, offer a compelling alternative to traditional metals like aluminum, steel, and titanium in aerial drone design. They possess a lower density and weight than metals while still maintaining excellent structural properties, resulting in lightweight yet sturdy frames ideal for drones. Composites offer superior strength-to-weight ratios, enhancing flight performance and efficiency compared to metal counterparts. 

Maintenance requirements are typically minimal due to their resistance to corrosion and fatigue, prolonging service life. However, the initial cost of composites and manufacturing processes tends to be higher than metals, although their performance benefits often justify the investment, particularly in high-performance or specialized drone applications where lightweight construction is critical. 

Overall, composites stand out as a preferred choice in aerial drone design, offering a compelling combination of lightweight, strength, and durability. SendCutSend’s composite material offerings range from Carbon Fiber and ACM Panel to Cork, G-10 and Phenolic

Other Materials

In addition to composites, aluminum, steel, and titanium, other materials finding application in aerial drone design include plastics, polymers and wood

Plastics offer versatility and ease of manufacturing, enabling intricate designs and lightweight components. They are often used for non-structural parts such as housings, covers, and propellers. 

Polymers like ABS (Acrylonitrile Butadiene Styrene) and nylon provide sufficient strength while being lightweight and cost-effective. However, they may lack the structural integrity and durability of metals and composites, limiting their use in critical load-bearing components. 

Wood can be beneficial in the design of aerial drones due to its lightweight nature, ease of machining, and natural vibration dampening properties. However, its susceptibility to moisture and environmental factors may require additional protective coatings or treatments for prolonged durability in outdoor settings. 

Density
(Weight/Volume)
Yield Strength
(Force per square inch at which material deforms permanently. This varies greatly according to the material type)
Cost ($)
Aluminum2.7 grams/cm35,000 – 87,000 lbs/in2$$
Steel7.8 grams/cm329,000 – 145,000 lbs/in2$$
Titanium4.5 grams/cm343,000 – 145,000 lbs/in2$$$
Composite1.5 – 2 grams/cm314,000 – 145,000 lbs/in2$$$
Plastic (ABS)1.0 – 1.4 grams/cm34,000 – 7,000 lbs/in2$
Wood0.3 – 1.2 grams/cm31,000 – 10,000 lbs/in2$

In Summary

Designing lightweight aircraft and drones while optimizing for weight poses several challenges. Balancing weight reduction with structural integrity is crucial, as lighter materials may compromise strength and durability. To address this, designers should prioritize materials with high strength-to-weight ratios, while employing advanced structural design techniques or testing to ensure safety and reliability in their application. Other considerations for a successful design include lightweight propulsion systems that deliver the required power, and materials that withstand the harsh environment the aircraft might find itself in.

Overall, a multidisciplinary approach and innovative solutions are necessary to overcome these challenges and achieve optimal weight reduction without sacrificing performance or safety.
The good news is that SendCutSend has more than 165+ materials in stock and only requires a $29 order minimum. With no quantity minimums and price reductions starting when you order at least two identical parts, it’s easy to go from prototyping to mass production runs without sacrificing time or quality. Get started today with instant pricing in just a few minutes.

Get our latest articles in your inbox!

Start your first SendCutSend project today!

Upload your CAD design, or try one of our customizable part templates to get instant pricing on your custom laser cut parts. All delivered to your door in a matter of days.

We proudly use hardware by PEM

Flush Standoff, 4-40, .250" Zinc plus Clear Chromate

Aluminum: 5052, 6061, 7075 Steel: Mild, G30

SKUSO-440-8
Thread Size4-40 x .250″
Hole size in sheet (+0.003/-.0.000).168″
Minimum sheet thickness0.040″
Maximum sheet thickness.125″
Fastener materialSteel
Minimum distance hole C/L to edge0.230″
When determining the distance between two or more fasteners, you can calculate the distance by the formula, C/L to edge + 1/2 the diameter of the second mounting hole..345″
Recommended panel materialSteel/Aluminum
Coating typeZinc
Length.250″
Aluminum material ranges (5052, 6061, 7075)0.040″-0.125″
Steel material ranges (CRS, HRPO, HR)0.048″-0.119″

We proudly use hardware by PEM

Flush Standoff, 4-40, .250" Passivated

Stainless Steel: 304, 316

SKUSO4-440-8
Thread Size440
Hole size in sheet (+0.003/-.0.000).166″
Minimum sheet thickness0.04″
Maximum sheet thickness.125″
Fastener material400 Stainless Steel
Minimum distance hole C/L to edge0.230″
When determining the distance between two or more fasteners, you can calculate the distance by the formula, C/L to edge + 1/2 the diameter of the second mounting hole. Example shown with x2 of the same hardware..313″
Recommended panel materialStainless Steel
Coating typePassivated
Length.250″
304 Stainless Steel material ranges0.048″-0.125″
316 Stainless Steel material ranges0.060″-0.125″