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How to Make a Drone / UAV – Lesson 1: Terminology
How to Make a Drone / UAV – Lesson 2: The Frame
How to Make a Drone / UAV – Lesson 3: Propulsion
How to Make a Drone / UAV – Lesson 4: Flight controller
How to Make a Drone / UAV – Lesson 5: Assembly
How to Make a Drone / UAV – Lesson 6: Get it all working together
How to Make a Drone / UAV – Lesson 7: FPV & Long-range
How to Make a Drone / UAV – Lesson 8: Aircraft

Now that you have either chosen or built a frame, the next step is to choose the right propulsion system. A complete propulsion system includes motors, propellers, ESCs and a battery. Almost all small multi-rotor drones / UAVs are electric, with almost none being gas-powered. For this reason, we will focus on implementing an electric propulsion using brushless DC motors.

1. Motor

The motors you use will have a huge impact on the payload (or maximum load) which your UAV can support, as well as the flight time. We strongly suggest using the same (propulsion) motor everywhere. Note that even if a pair of motors are the same brand and model, and from the same production run, their speeds may vary slightly, which is something the flight controller will take care of.

Brushed DC Motor

Inrunner Motor

Brushless DC Motor

Brushless DC Motor

Brushless DC "Pancake" Motor

DC “Pancake” Motor

Brushed vs Brushless

Brushed motors spin the coil inside a case with fixed magnets mounted around the outside of the casing. Brushless motors do the opposite; the coils are fixed either to the outer casing or inside the casing while the magnets are spun. In most situations, you will be considering only brushless DC motors. Brushless DC motors are used extensively in the hobby RC industry for products ranging from helicopters and airplanes to the drive system in RC cars and boats. “Pancake” brushless motors have a larger diameter and are essentially flatter and often allow for higher torque and lower KV (details below). Smaller UAVs (usually the size of the palm of your hand) tend to use small brushed motors because of the lower price and simpler two-wire controller. Although brushless motors come in a variety of different sizes and specs, selecting a smaller brushless motor rarely means it will be less expensive.

Inrunner vs Outrunner

There are a few types of brushless DC motors:

  • Inrunner – these have the fixed coils mounted to the outer casing and the magnets are mounted to the armature shaft which spins inside the casing (tend to be used on RC cars because of the high Kv)
  • Outrunner – these have the magnets mounted on the outer casing which is spun around the fixed coils in the center of the motor casing (the bottom mounting of the motor is fixed).
  • Hybrid outrunner – technically outrunners but have a static outer shell around them to make them look like they’re inrunners

Inrunner brushless DC motors tend to be used in RC cars, airplanes and helicopters because of their high KV. They may also be geared down to increase the torque. Outrunners tend to have more torque.

“KV”

The KV rating / value of a motor relates to how fast it will rotate for a given voltage. For most multirotor aircraft, a low KV is desired (between 500 to 1000 for example) since this helps with stability. For acrobatic flight however, you might consider a KV between 1000 and 1500 and also consider using smaller diameter propellers. If the KV rating for a particular motor is 650rpm/V, then at 11.1V, the motor will be rotating at 11.1V x 650 = 7215rpm. If you operate the motor at a lower voltage (say, 7.4V), the rpm will be 7.4V x 650rpm/V = 4810rpm. It is important to note that using a lower voltage tends to mean that the current draw will be higher (power = current x voltage).

Thrust

Some brushless motor manufacturers give an indication of a motor’s thrust corresponding to several propeller options (often presented in a table). The unit of thrust is often Kg, Lbs or N. For example, if you are building a quadcopter and find that a specific motor can provide up to 0.5Kg of thrust with an 11 inch propeller, that means that four of these motors (with that given prop) can lift 0.5Kg*4=2Kg at maximum thrust. Therefore if your quadcopter weighs just less than 2Kg, it will only take off at maximum thrust. You need to either choose a motor + propeller combination which can provide more thrust, or reduce the weight of the aircraft. If the propulsion system (all motors and props) can provide 2Kg of thrust (max) then your entire copter should be at most about half this weight (1Kg, including the weight of the motors themselves). The same calculation can be done for any given configuration. Let’s assume a hexacopter‘s  weight (including frame, motors, electronics, battery, accessories etc) to be 2.5Kg.  Each motor should therefore be capable of providing (2.5Kg/6 motors) x 2:1 = 0.83kg of thrust (or more). You can now calculate the specs of your motor(s) but suggest reading through the sections below before making a decision.

Additional Considerations

  • Connectors: Brushed DC motors have two connectors: one for positive, the other for negative. Reversing the wires reverses the rotation of the motor.
  • Connectors: Brushless DC motors have three connectors. Refer to the ESC section below to know how to wire them and reverse direction of rotation.
  • Windings:  The windings impact the KV of a motor. When you want a lower KV but maintain the torque, you may need to consider a larger pancake-style brushless DC motor.
  • Mounting: Most manufacturers have a general mounting pattern for brushless DC motors which has allowed companies which produce frames to not have to design adapters. The pattern is normally metric, with two holes spaced 16mm apart, and another two holes spaced 19mm apart (at 90 degrees to the first).
  • Thread: The mounting thread used to secure a brushless motor to a frame can vary. Common metric screw sizes include M1, M2 and M3 and imperial might be 2-56 and 4-40.

2. Propeller

Propellers for multi-rotor aircraft are adapted from propellers used in RC airplanes. Why not use helicopter blades? Although it has been done, imagine the size of a hexacopter which used helicopter blades. Note that a helicopter-type system also requires that you vary the pitch of the blades which significantly adds to the mechanical complexity. You may also ask why not use a turbojet, turbofan, prop-jet etc? These are incredibly good at providing a lot of thrust, but also require a lot of power. If the objective of the drone was to move really fast rather than hover in confined areas, one of these may be a good option.

Propeller

Propeller

Blades & Diameter

Most multi-rotor aircraft have either two and three rotor blades, with the most common being two. Do not assume that adding more blades will automatically mean more thrust; each blade must travel through the wake of the one which precedes it, so the more blades, the more prevalent the wake will be. A smaller diameter propeller has less inertia and is therefore easier to speed up and slow down, which helps in acrobatic flight.

Propeller Diameter

Propeller Diameter

Pitch / Angle of Attack / Efficiency / Thrust

The thrust produced by a propeller depends on the density of the air, on the propeller’s RPM, on its diameter, on the shape and area of the blades and on its pitch. A propeller’s efficiency relates to the angle of attack which is defined as the blade pitch minus the helix angle (the angle between the resultant relative velocity and the blade rotation direction). The efficiency itself is a ratio of the output power to the input power. Most well-designed propellers have an efficiency of 80%+. The angle of attack is affected by the relative velocity, so a propeller will have different efficiency at different motor speeds. The efficiency is also greatly affected by the leading edge of the propeller blade, and it is very important that it be as smooth as possible. Although a variable pitch design would be best, the added complexity required as compared to a multirotor’s inherent simplicity means a variable pitch propeller is almost never used. Additional information regarding the theory behind blade design and thrust generated can be found online at sites such as the MDP project. There are also several online tools which help calculate a propeller’s thrust. Certain sites list a variety of motors such as eCalc for the thrust calculations

Propeller Pitch

Propeller Pitch (one revolution)

Propeller Angle of Attack

Propeller Angle of Attack

Rotation

Propellers are either designed to rotate clockwise (CW) or counter-clockwise (CCW). It is important to know which part of the propeller is intended to face upwards (the top surface is curved outward). If the design of your multirotor inverts some of the motors (as is the case for a Vtail, Y6, X8), be sure to change the orientation of the propellers so the thrust is still downwards. The top of the propeller should always face the sky. The documentation associated with the flight controller (discussed in the next lesson) normally shows you which way each propeller is intended to turn for each multi-rotor it supports.

Counter Rotating Propellers

Counter Rotating Propellers

Material

The material(s) used to make the propellers can have a moderate impact on the flight characteristics, but safety should be the primary consideration, especially if you are new and inexperienced.

Plastic

Injection-Molded Plastic (ABS / Nylon etc.) is the most popular choice when it comes to multi-rotor aircraft. This is largely because of their low cost, decent flight characteristics and respectable durability. Normally in a crash, at least one propeller ends up broken, and while you are calibrating the drone and learning to fly, you will end up with a lot of broken propellers. A plastic propeller which has been reinforced with carbon fiber is arguably the best overall choice because of its high rigidity and low cost.

Fiber-Reinforced Polymer

A fiber-reinforced polymer propeller (carbon fiber, nylon reinforced carbon etc.) is “cutting edge” technology in more ways than one. Carbon fiber parts are still not very easy to produce and as such you pay quite a premium for them over a plastic propeller with the same specifications. In the event of a crash, a carbon fiber propeller is harder to break and flex and as such will cause more damage to whatever it contacts. This having been said, if you want to consider a fiber-reinforced propeller, they are normally well made and rarely require balancing, are stiffer (so fewer losses in efficiency due to flexing etc) and are lighter weight than other materials. We suggest considering these high performance propellers only after you are comfortable flying.

Natural

Natural materials such as wood are not used often to make propellers for mulitirotors as they require machining to produce and therefore cost more than plastic. The main advantage heere is that wood is quite strong and will not bend. Wood propellers are still used for RC airplanes.

Propeller Materials

Propeller Materials

Folding

Folding propellers have a central part which connects to two pivoting blades. When the center (which is connected to the motor’s output shaft) spins, centrifugal forces act on the blades, forcing them outwards and essentially making the propeller “rigid”, with the same effect as a fixed propeller. Because of lower demand and higher number of parts required, folding propellers are less common than fixed propellers. As expected, a folding propeller makes transporting the aircraft quite a bit easier, and combined with a folding frame, the “retracted” size of the UAV can be significantly smaller than in flight. Folding propellers also have a nice advantage of only having to change one blade in the event of a crash.

Folding Propeller

Folding Propeller

Mounting

Since aerial vehicles can come in a wide range of sizes, so can propellers. As such, there are a few somewhat more “standard” sized motor shaft diameters in the industry. Propellers often come with a small selection of these adapter rings (which look like washers with various different diameter holes in the middle) to press into a cutout of the propeller so it centers it on the motor’s shaft. If you find that the center (“bore”) of the propeller you are using is way too large for the shaft of your motor, you will need the spacer / adapter ring. Don’t assume that the propeller you are purchasing includes the adapter; check the bore and compare it to your motor’s shaft diameter.

Certain manufacturers further customize the way the propeller mounts to the motor. Some have D-shaped (single or double) cutouts on the motor, and the propeller has the missing material; this ensures that the propeller will not loosen itself in flight. Other manufacturers have been known to include other types of specific “male / female” motor to propeller connections as well. Newer propellers have a thread rather than a hole which is opposite to that of the rotation, and the motor’s shaft has the same thread, essentially tightening the propeller when rotating.

Prop savers

Prop savers replace the normal propeller adapter on a motor and have a small part (such as an O-ring) which keeps the propeller in place. In the event of a crash, the propeller is normally prevented from rotating (ex it contacts an object) and since the motor is still rotating and high speeds, it causes the O-ring to either rip apart of fly off, ideally saving both the motor and the propeller from damage. As great as this might be, there are a few disadvantages:

  • The propeller sits higher on the shaft
  • If the design of the prop saver is off, or not properly centered center it can lead to vibration
  • Check O-rings periodically since they may become brittle and crack in flight

Prop guards

Propeller guards (“prop guards”) connect to the main frame and provide a fixed ring / cushion around the propeller. Should the UAV contact an object, ideally the propeller guards will contact the object first and withstand the impact so the propellers are not touched. Small toy multi-rotor UAVs often have removable plastic prop guards included. As always, there are some compromises to using prop guards:

  • They can be a high source of vibration
  • Only good for low force impacts
  • Can lower thrust if there are too many supports directly under the propeller wash
Prop Guard

Prop Guard

Balancing

Most inexpensive propellers are not very well balanced, which can be seen by simply balancing the center on a pencil (one side will likely be heavier than the other). As such, it is always good practice to balance your propellers before fixing them to the motors. It is very important that the propeller be balanced because if not, the vibrations caused by an unbalanced propeller often propagate to the flight controller, causing erratic flight. A propeller can be balanced many ways, but if you are building your own UAV, then an inexpensive prop balancer is ideal. A prop balancer simply allows you to easily see where there is a weight unbalance in the propeller. In order to adjust the weight, you can either sand down the heavier part (evenly sand the center part of the propeller only as opposed to leading or trailing edges, and DO NOT cut off part of the propeller), or add clear masking tape (which is very thin) to the lighter side (and keep adding lengths of tape evenly until it is balanced). Note that the farther away from the center you make the modification (sanding or adding tape) the more of an effect it will have based on the principle of torque.

Propeller Balancer

Propeller Balancer

3. ESC

An ESC (acronym for “Electronic Speed Controller“) is what allows the flight controller (covered in the next lesson) to control the speed and direction of a motor. The ESC must be able to handle the maximum current which the motor might consume, and be able to provide it at the right voltage. Most ESCs used in the hobby industry only allow the motor to rotate in one direction, though with the right firmware, they can operate in both directions.

Brushless ESC

Brushless ESC

Connectors

An ESC might initially be confusing because it has several wires exiting on two sides.

  • Power input: The two thick wires (normally black and red) are to obtain power from the power distribution board / harness which itself receives power directly from the main battery.
  • 3 bullet connectors: These pins are what connects to the three pins on the brushless motor. There are some standard sizes in the industry, but if you find the two are mismatched, you will need to replace one set.
  • 3-pin R/C servo connector: This connector accepts RC signals, but rather than requiring 5V on the red and black pins, most of the time an internal BEC provides 5V to power the electronics.

In certain instances, the manufacturer does not want to assume which connectors you are using, and leaves the wires for the motor connection and power input bare (they may provide bullet connectors in the packaging which you may or may not want/need and would have to solder onto the wires). The bullet connectors you received with the motors may also not match those of the ESC, so in this case, it’s simply best to replace one or the other. Your next question is obviously given three bullet connectors, which one plugs into which on the motor? As far as the connector for the power, this is entirely up to you – ideally you would use connectors to make the ESC easily removable in case of failure, or if you want to use it on a different project, but be sure that the positive on the ESC goes to the positive on the battery, and same for negative. In order to reverse the direction of rotation, swap any of two of the three connectors between the ESC and the brushless motor.

BEC

Most ESCs include what is called a “Battery Elimination Circuit” or BEC. This comes from the fact that historically, only one brushless motor was needed in a given RC vehicle, and rather than splitting hte battery, it would just need to be connected to the ESC, and the ESC would have an onboard voltage regulator to power the electronics.It is important to know the current which an ESC’s BEC can provide, though it is normally in the range of 1A or above and is almost always 5V.

In a multi-rotor, you need to connect all ESCs to the flight controller, but only one BEC is needed, and having power coming from multiple sources all being fed to the same lines can potentially cause issues. Since there is normally no way to deactivate a BEC on an ESC, it is best to remove the red wire and wrap it with electrical tape for all but one ESC. It is still important to leave the black (ground) wire in place for “common ground”.

Firmware

ESCs are not all equally good for use with multi-rotors. It is important to understand that before multi-rotors were around, that brushelss hobby motors were used primarily for RC car drives, airplane propellers and as primary motors in model helicopters. Most of these applications did not require very fast response time or rapid updating. An ESC equipped with SimonK or bheli firmware is able to react very fast (much higher frequency) to changes in input, which may mean the different between stable flight or a crash.

Power Distribution

Since each ESC is powered from the main battery, the main battery’s single connector must somehow be split amongst four ESCs. To do so, a power distribution board, or power distribution harness is used. This board (or cable) splits the main battery’s positive and negative terminals into four. It is important to note the type of connectors used on the battery, ESC and power distribution board may not all be the same, and it is best, whenever possible, to choose a “standard” connector (such as Deans) which is used throughout. Many inexpensive boards require soldering, as they do not want to assume you are using any specific connector. A very simply power distributor could involve a two input terminal block or soldering all positive connections together, and then all negative connections together..

4. Battery

Chemistry

Batteries used in UAVs are now almost exclusively Lithium polymer (LiPo), with some more exotic ones being Lithium-Manganese or other Lithium variations. Lead acid is simply not an option and NiMh / NiCd are still too heavy for their capacity and often cannot provide the high discharge rates needed. LiPo offer high capacity with low weight, and high discharge rates. The downsides are their comparatively higher cost and continued safety issues.

Voltage

You should really only need to consider one battery pack for your UAV. This battery’s voltage should correspond with the motors you chose.  Almost all batteries used these days are lithium-based and incorporate a number of 3.7V cells, where 3.7V = 1S. Therefore a battery which is marked as 4S is likely 4 x 3.7V = 14.8V nominal. Providing the number of cells however will help you determine which charger to use. A single cell high capacity battery may physically look a lot like a low capacity multi-cell battery.

Capacity

A battery pack’s capacity is measured in amp-hours (Ah). Small battery packs can be in the range of 0.1Ah (100mAh) though battery packs for medium sized drones are 2-3Ah (2000mAh-3000mAh). The higher the capacity, the longer the flight time, but the heavier the pack will be. You can expect the flight time of a normal UAV to be in the order of 10-20 minutes, which might not seem like a long time, but you need to consider it’s always fighting against gravity, and unlike an airplane, there are no surfaces to help with lift.

Discharge Rate

The discharge rate from a lithium battery is measured in C, where 1C is the capacity of the battery (normally in amp hours unless you’re looking at a very small drone the size of your hand). The discharge rate of most LiPo batteries is at least 5C (five times the capacity), but since most motors used in multirotors consume high current, the battery needs to be able to discharge at incredibly high current, which is often in the order of 30A or more.

Safety

LiPo batteries are not entirely safe since they contain pressurized hydrogen gas and have a tendency to burn and/or explode when there is something wrong. As such, if you have any doubts about the battery pack you are holding, DO NOT plug it into the UAV or even the charger – consider it a “write off” and dispose of it properly. Telltale signs that something is wrong include dents or the battery is larger than it was when you first received it (i.e. leaking gas). When charging a LiPo battery, it is best to keep it in a LiPo safe bag. Storing the battery is also ideally done in a LiPo bag as well. In the event of a crash, the first thing you need to do is unplug and check the battery. Having the battery in a fully enclosed case may add to the weight, but can really help keep your battery safe in a crash. Certain battery manufacturers sell batteries with and without a hard case.

Charging

Most LiPo batteries have two connectors: one is intended to be the main “discharge” wires which can handle high current, while the other, normally smaller and shorter one is the charging connector. This charging connector is almost always a white JST connector which has one ground pin following by the same number of cells used to create the pack. This is what you connect to the LiPo charger which then takes care of charging (and balancing) each internal cell. The charger should indicate when charging is complete and, given the safety issues with LiPo batteries, it is best to unplug the battery and charger when charging is complete.

Mounting

The battery pack is the heaviest item on the UAV and as such, should be placed dead center to ensure the motors are subjected to the same load. A battery does not include any specific mounting (especially screws which could puncture the LiPo and cause a fire), so some mounting methods currently used involve Velcro straps, rubber, plastic compartment among others. Having the battery suspended below the frame using Velcro is quite popular because of accessibility.

LiPo Battery

LiPo Battery

 

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209 Responses to “How to Make a Drone / UAV – Lesson 3: Propulsion”

  1. Marius

    Hi
    I hope you can help me….it make sense to me- and that is what everyone recommend- that the esc must have a amp rating which is higher than the max current draw of the motor it will supply. But I also see that you, and many other manufacturers, recommend a esc with a amp rating which is lower than the max rating of the motor.
    Is the esc current rating specced at a different voltage than the current rating of the motor?
    Regards
    Marius

    • Coleman Benson

      @Marius If the motor will draw maximum current (maximum thrust), then the ESC needs to be able to provide that current. There may be a few rare instances where the ESC’s maximum current is below the motor’s maximum current, and it’s likely a compromise for reduced cost.

  2. shikhar

    sir can you guide me for this that how to mange the price and what it will cost for all to be prepared

  3. shikhar

    i actually wanna know that making this project at home in all simpler manner, then what will be estimated in rupees. great honour for ur help sir

    • Coleman Benson

      @Salaris High Kv usually means higher RPM and less torque. The upside is you can use smaller propellers and get a faster response, but lower payload capacity. “Rule of thumb” can be 1Kg quad should (ideally) use <1000Kv.

  4. anil kasana

    hi sir , m mechanical engineering student i want your help . m going to make a project of uav . which can carry 5 litter water. m great lover of nature . i want to grow more n more plants in remote areas. plz suggest me best model n best component of uav model.
    plz send me mail on my gmail…..
    anilkasana4003@gmail.com.

    • Coleman Benson

      @anil kasana Carrying 5L means carrying around 5Kg (not including the weight of the container) which does not include the weight of the UAV itself or the battery, which means the complete platform will likely weight around 8-10Kg, which is actually avery heavy platform. You will therefore need to consider a very large multirotor vehicle (likely a hexacopter or octocopter). If you are prepared to spend several thousand dollars on such a platform, please contact us via the RobotShop Forum with an idea of your budget and requirements and we will see what can be put together.

  5. Shripal

    If I use a microcontroller should I use a ESC?
    Can I make 3 inputs of a brushless motor to 2 inputs

    • Coleman Benson

      @Shripal A microcontroller cannot control a brushless DC motor – you need one ESC per motor. If you use one ESC to power two motors, it needs to be able to provide enough current, and you won’t have the ability to control each motor separately. It’s best to have one ESC per motor.

  6. honey

    hi sir,this is honey,i am a since student(mca),but i am interesting to build a drone,it’s maximum flying time 6 hours — 8 hours etc, it is to use to carry a 10 kg weight with attachment of a 200 meters rubber pipe.
    ——————->my main doubt
    1)it is designable or not?
    2)if it is not,than what requirements i need?
    3)if it is possible,it’s budget how much require?

    • Coleman Benson

      @honey If the drone is an airplane, it is possible. If the drone is a multirotor which always needs to fight against gravity, it’s rare that they operate beyond 30 minutes (most operate for under 20 minutes). 10Kg is also quite a heavy payload for any type of UAV, and the fact that you need it to drag 200m of pipe does not seem practical.

  7. Rutuja

    Hi Coleman, please tell me whether we must use ground station (ex. Laptop or mobile) or complete Drone can be controled with the use of RC transmitter. Also if we are using only RC transmitter, how to receive data from flight controller to ground station, if we want to receive.

    • Coleman Benson

      @Rutuja You rarely need a computer when operating a drone; the ground control station is used primarily when you have a controller in a box, a large video display, several transmitters and receivers (and possibly a computer), and sometimes a larger directional antenna. For waypoint navigation however, the GPS coordinates are saved on the drone itself, after which the computer is not needed unless you are getting feedback. What are your objectives?

  8. Rutuja

    Thank you so much for your reply coleman. The objective of our project is to develop a Drone having capability of handling payload of 1.5 Kg and should be able to travel for a distance of 8 Km.

  9. Avi

    Hi Coleman Benson,
    It was really very helpful and informative link. Can you please help me out in solving a small query?
    If payload is 5Kg including everything(battery,frame,etc.) ,Propeller Size is 13 inches with 4 blades and overall size is 32 inches. Then what battery specs should i choose.. So that it can get 10 Kg of thrust. Don’t include ESC and motor specs for now.
    i.e. , can 10000mAh provide me a thrust of 10kg.
    Thanks in advance…..

    • Coleman Benson

      @Avi You need to know the specifications of your motors when you use 13″ propellers while operated at a specific voltage. The battery does not determine thrust. If you don’t have these specs, you might need to do some testing. A 10Ah battery pack is actually quite large and heavy (are you certain that’s within your 5Kg total weight?).

  10. Rutuja

    Hi Coleman, The requirement of our project is to have thrust generation of 600 g. Can you please suggest the suitable motor, propeller ESC combination for our thrust requirement.

    • Eric Nantel

      @Rutuja To choose the right power system, you need to know the total weight of your assembly including everything. Motors are rated at maximum thrust production. If you need a total of 600g including everything, many choices are available. Here is a suggestion:
      T-Motor AIR 350 Multirotor Kit

  11. bhushan

    Sir actually these lesson will be also helpful for my cllg project ty so much…:)

  12. Nate

    How do you pair a motor to an ESC? I know the ESC needs to be able to handle the maximum amount of current, but what about the voltage? Does it matter? The ESCs I have seen have had a much lower input voltage than the motor.

    • Coleman Benson

      @Nate Most ESCs should have a voltage rating (or min/max). Since the common voltages used by brrushless DC motors for hobby use are 3S (11.1V) or 4S (14.4V), some manufacturers simply make the assumption that this is what you’ll apply and don’t list the specs on the ESC. If you’re not sure, it’s best to contact the manufacturer.

  13. vaibhav Patil

    sir i want to make a drone which can carry approx 5-6 kg weight and flight time around 30 min,so for these which battery and motor i should select as in according to there specs

    • Coleman Benson

      @vaibhav Patil 5-6Kg payload is actually quite a bit, especially if you also want a 30 min flight time (which means a lot of batteries). Take a look at the procedure for choosing motors and propellers and we suggest considering at least a hexacopter design.

  14. vaibhav Patil

    Yes sir i am going to make hexacopter only so for that i am thinking of using two Multistar 10000Amh batteries and 940kv bldc motor and depending upon these what size propellers i should select , will these be enough to achieve my target ?

    • Coleman Benson

      @vaibhav Patil Two 10,000mAh batteries (likely 11.1V?) are quite heavy – that makes for a very large hexacopter. Can you find a large BLDC motor which provides thrust based on propeller size? You will likely be considering propellers in the 14″ (or larger) range.

  15. K.Mohan

    Can I have some Regression Models (benchmarking) of Key Parameters of proven Electric-powered UAVs with Fixed Wings, please? Many thanks in advance.

    • Sébastien Parent-Charette

      @K.Mohan: We do not have regression analysis of fixed wings UAVs to share. You can probably find some by performing an online search.

  16. Jonas Woodruff

    Starting with a Tarot Iron Man 650 building my first UAV. Learning lots and thanks so much for this publication. Looking at props I keep finding matched pairs with one a CW and one a CCW. Can you please tell me why props are sold in matched pairs of CW and CCW?

    • Coleman Benson

      @Jonas Woodruff Almost all multirotor UAVs are symmetric about the center axis and as such, the propellers need to spin in the opposite direction. Selling the propellers in pairs decreases the chance that customers will buy the wrong quantities of each type of prop.

  17. Abhishek

    Sir I have not understood the concept of angle of attack and blade pitch.could u please guide me!

    • Coleman Benson

      @Abhishek Think of a propeller blade like part of a screw: it has a certain pitch and angle. The distance traveled for one revolution of the propeller is the pitch, whcih also relates to the angle of attack. If you find a resource online where you feel the explanation is better described or presented, we invite you to bring it to our attention.

  18. Bizby

    Hi 🙂 I need some guidance. I want to make a tricopter for my paper license and i want to calculate the thrust for my propellers. But i can’t find anywhere how to calculate. I need some mathematical formulas. I found for planes. Is it the same formula? can i use that for my propeller for tricopter?

  19. Amey Ganore

    sir
    I want to know can phone camera be connected to the drone if yes please can you tell me the materials for connecting phone camera or camera to it

    • Coleman Benson

      @Amey Ganore Certain cameras like the GoPro are able to send video wirelessly (WiFi) to smart phones. You need to download the app.

  20. Tomas

    Hello, first of all thanks for the post, is very helpfull for beginers like me. Can you explain me this sentences please?, i dont know if a couldnt undestand it or in the second “ESC” should be “BEC”. “In a multi-rotor, you need to connect four or more ESCs to the flight controller, but only one ESC is needed, and having power coming from multiple sources all being fed to the same lines can potentially cause issues”.

  21. rob

    i was interested in learning more about the micro pancake motors. or “penny motors” can these be put on quadcopters, and do they make brushless pancake motors that are doule shafted? or even a “double shafted brushless inrunner”?

    • Coleman Benson

      @rob it’s certainly possible; most tend to use brushed DC motors for small UAVs simply for the $ savings. BLDC pancake motors are certainly preferable.

  22. Arvind Kukreti

    I bought a bldc motor having specification- Biggest Thrust (g/s) – 1200/4
    What does it mean?

    • Coleman Benson

      @Arvind Kukreti normal conventions would mean g/s translates to grams per second, whereas the normal unit for thrust is a force (g, Kg, N, oz, lbs etc). Can you indicate where you found these units?

    • Coleman Benson

      @kshitij Certainly, but the cheaper you get, the more you will have to do (electronics and programming). It all comes down to your abilities.

  23. Kamal

    Hi,
    I’m an aeronautical engineering undergraduate designing a multicopter for my final year project.
    The multicopter should be capable of:
    Lifting a 60kg payload
    Travelling a distance of 50m
    Flight time sufficient to cover required distance.
    I’ve selected KDE’s strongest motor and ESC. However the current rating of the recommended ESC is lower than the current rating for the motor.
    The ESC is recommended by the manufacturer, however are they really compatible? Would the system work?
    Furthermore which battery would you recommend?

    • Coleman Benson

      @Kamal It may be that they never expect the motor to reach max current. Normally we would suggest the ESC be able to provide more current than the motor, but with such a large UAV, the ESC they suggest may be the largest they were able to find and test. In terms of the battery, we can only suggest LiPo, but we don’t have anything large enough for a 60Kg UAV. We suggest not purchasing any parts until you have worked out if they will all be compatible, including the battery.

  24. Varun Kumthekar

    This tutorial was really helpful, but i have the same question as Mr. Arvind. I came across this motor with biggest thrust being specifies as 1200/4. Can you help me with what those specifications mean
    Here is the link : amazon.in/gp/product/B00MTHGH1S/ref=pd_lpo_sbs_dp_ss_2
    Will 4 such motors be able to lift weight of about 2.5kgs (Quadcopter + payload) and will 2200mah 20c battery suffice. Will arduino be good controller for the same

    • Coleman Benson

      @Varun Kumthekar Honestly don’t know what those units are. Try contacting the seller. If you want to program the Arduino entirely yourself, that will take quite a lot of time.

  25. Ethan

    Hi I am thinking about make chinook and I need some advice on how to to like what motors to buy I would like it to carry about 2.5-1.5 kg in pay load and a about 45-50cm long so I know I will need to get two brushless Motors and servos to run the hatch a the back ad battery and receivers and remote but do you have any tips on were to get them from and how to build the frame thanks please email

    • Coleman Benson

      @Ethan Not many flight controllers allow for a chinook design because each propeller requires more than just one motor (i.e. is not “simple”). A 2.5Kg payload is quite impressive, so your rotors (and corresponding motors) will likely be quite large. You’re back in the realm of normal RC rather than drones.

  26. Ayo

    Dis is so good and thoroughly detailed but still I would like to know how to calculate the thrust, based on the kv ratings and the propeller size. With this I would be able to calculate acurately the total thrust of my four propellers. Thanks man

    • Coleman Benson

      @Ayo We may create a tool in the future, but for now, take a look online and there are quite a few free websites which will allow you to do exactly what you describe.

  27. ralrigs

    Hello , i have a motor broken lh x10 drone and i would like to build a rc drone with the controller board of this x10 , do you think its possible to use rc frame and rc motor with esc with those board , to make a mod with the black yellow input and black red motor output of the controller .thank you , great article series about drone , you did a great job !

    • Coleman Benson

      @ralrigs Appreciated. Note that the electronics included with the lhx10 drone are not really modifiable, so hackig the unit is not easy. The motors are also brushed, not brushless. Consider building a new drone from scratch.

  28. ralrigs

    Ok ty , after some more research its not possible that way as ESC apparently need PWN signal http://robots.dacloughb.com/project-2/esc-calibration-programming/ and not DC input , it would need another controler like a arduino then and some more programing , better go directly with an arduino from scrach,ill make back a diy drone with that board and ship an arduino mini pro wich look very interresting , thanks

  29. saisaching

    sir, iam planning a quadcopter drone. i liked your lessons sooo much and they helped me to know more about drones.but i have a small cofusion in placing the motors .i.e. if iam using an 1400kv motor or above (4 motors) then what is the recommende lipo battery for my entire drone.

    • Coleman Benson

      @saisaching The two are not related – when you choose your battery, take a look at the input range of the motor. Normally 1400kv corresponds to a specific voltage.

  30. Geoffrey Nyaga

    Hi, I am currently making a fixed wing drone and overall weight including electronics and prop is 2.5kg. i have a 1020kv motor and 11x7e prop and a 11v lipo battery. will this be enough to make it fly? i have a 2m wingspan

    • Eric Nantel

      @Geoffrey, One of the best way to calculate all that is the eCalc software.

  31. love

    sir please suggest me the finest structure of the quadcopter…bcz this is mine project and i wanna make it very differnt from other model…so i need ur help bcz i think you can only show me the right way of making the better quadcopter..!!

    • Coleman Benson

      @love If you are looking to make a custom quadcopter, but for it to be different than the others, but do not know where to start, we strongly suggest getting experience designing and building a normal quadcopter or two before trying something different.

  32. chinalu

    thanks for every thing SIR, can u plz explain on the pattern for propeller rotation for left,right etc

  33. Jatin

    hello sir, I am making gesture controlled quad copter. I want to know that which transmitter and receiver circuit I can use to make it gesture controlled??Does it require programming??

  34. Aniket

    Sir your article is awesome. My point is, i want to make a drone ( quadcopter) which can lift 4.5 to 5 kg of load except 2 kg his own weight. So which type of motor and battery how many amps) i should use to do it?

  35. Amireza

    I would really need help to understand the contributing factors to the thrust force as measured in the following: T = Ct ρ A (ΩR)^2
    especially which parameters can you change to improve the capability of a motor-propeller
    system to provide more thrust? and its correlation to the equation above.

    Your article has been really useful and Ive been able to extract some info on this but not in a packed complete precise way.

    Really appreciate your feedback

    • Coleman Benson

      @Amireza We certainly understand that ideally we would provide equations and how each variable factors into thrust. The objective of this article however is a bit more basic. You might try seeing the corelation between thrust on a multirotor and thrust on an airplane (there are many articles about this online with equations).

  36. robert

    Hi! I’m new in the hobby and have a more likely dumb question. What is the difference between two brushless motors that have the same kv but different sizes? Say for example a 2822 1300kv and a 2208 1300kv. I know one is bigger than the other one, but what is the pros and cons of each?
    Thanks in advance!

    • Coleman Benson

      @robert It really depends on the manufacturer – normally a larger diameter means more internals, which can create more thrust. The “kv” rating is a measure of rotations per voltage, but not thrust.

  37. suzan

    hello sir! I want to add a gripper on a quadcopter to lift at least 500g. would you please advise me what quadcopter should I use and which gripper kit ? and is it possible to control the gripper from an application or something ?

    • Coleman Benson

      @suzan We only carry one quadcopter which has mounting for a gripper: http://ow.ly/4npvmP The underside has mounting holes for the Litle Grip Kit: http://ow.ly/4npvwW (you need a Hitec 422 servo as well as some mounting screws / nuts). You can control the gripper directly from one of your RC remote control’s spare channels (connect the servo directly to the RC receiver).

  38. Luka

    hello sir, i want to calculate specifcations propellers for a given speed. that is, if I want to have a given lift force, how to fix the propellers that allow for this value of force? knowing that we have not the pitch of the propeller, Thanks

  39. Denniz Dcosta

    how to avoid red dot indication on propeller in fixed wing uavs?

    • Eric Nantel

      @Denniz Dcosta, What exactly do you try to avoid ? We do not understand the “Red Dot Indication”

  40. sujit

    I made some upgrades in my rc helicopter. Thats why it’s weight is almost reached to 10 kg. The old motor is not working. So which motor can handle and fly with 10 kg weight . Please help..

    • Eric Nantel

      @sujit, you need to determine the thrust needed to carry all the weight of your helicopter. Some brand provide ready made thrust sheets that you can use to choose your motor, it will give you information on the thrust in relation to the propeller and battery. There is a nice software called eCalc that can help as well.

  41. Tarn

    i m an mechanical engineer of 1st year…i want to make a quadcopter which can lift about a kg but i dnt know how to make it moveable in different directions. Can you help me on this

    • Coleman Benson

      @Tarn Moving in different directions is fundamental to multi-rotors. If you’re planning to create a custom multirotor, simply read through this tutorial series to figure out how a flight controller and RC system allow you to control its motion.

  42. Shimon

    Sir
    I am planning to build a quadcopter which can lift a playload of about 2kg . I am planning to make it as an autopilot which is GPS enabled.
    My main intention is to make use of this drone in delivering small stuffs around 3km radius. It should have a flight time not less than 25 minutes.
    Is it possible? Can you tell me what are the requirements? Please help me out sir. I have been behind this for months!

    • Coleman Benson

      @Shimon It is certainly possible, but it’s a custom project and you will have to learn a lot about how to make a drone, as well as long-range communication.

  43. Shimon

    Thank You sir,
    Can you please suggest me the following :
    1) The battery capacity (mAh)
    2) The motor with its rpm
    3) The mean or method of long range communication

  44. sahil

    can you suggest me a set of motor and prophelors have thurst of 45kg.

  45. Shubham pareek

    Hi, I need a little help as I’m stuck. I bought 1400kV motors and I’m using 10*4.5 props. I’m having trouble flying my drone.kindly suggest me different props coz someone suggested me to change the motors, but I cannot since I’ve invested a lot, so the only option is to tweak the prop size. Please, help me

    • Coleman Benson

      @Shubham pareek You’ll need to provide more explanation regarding the “trouble”. If the motors are too weak to lift it, then you either need to take off quite a bit of weight (somehow), or use more powerful motors + props. The prop size can be increased up to a certain diameter (see the motor details / specs to get an idea of the max suggested prop diameter). You should be able to cut down on weight somehow – even if it means drilling holes (which do not affect the structural integrity).

  46. Donald

    pls sir where can source for the parts, its very difficult getting them in Nigeria

  47. Malomo victor

    How can this materials be gotten in a rural area in Nigeria

  48. Rachit

    How to make pcb circuit and where do all this material be available

  49. Alireza

    Hi
    I am going to build a Fixed wing UAV , with atlas 30 minutes flight. and abt 5~8 KG.
    Which motor is good for me?? electrical or diesel? with which battery? and is it possible to connect that to APM autopilot?

    • Coleman Benson

      @Alireza You should be able to get 30 minutes of flight from a normal brushless DC motor and propeller. If you are in the brainstorming stage, we suggest creating a new topic on the RobotShop Forum. We can provide ideas for the frame, motors, autopilot etc.

  50. Alireza

    So it is wiser to use electrical motor for 30 min fixed wing,8 KG ,25m/s,1000ft instead of diesel motor?
    can u give me a start point of calculation and what battery and motor is needed?

    • Coleman Benson

      @Alireza They each have their advantages / disadvantages – most “drones” are still multirotor rather than aircraft, so the best research / discussion between gas powered and DC brushless motors for fixed wing can be found on RC airplane forums. Same goes for the calculations.

  51. akmal

    sir i am working for radar free drone
    i need to know any chemical element that do not react on any chemical reaction and cannt give singnals

  52. krishnakumar

    Sir,I want know about the control unit and its proper assembly of drone(uav) can you help me with that stuff

    • Coleman Benson

      @krishnakumar There should be a user guide with the specific flight controller you select, explaining how to make all the necessary connections, as well as how to connect it to the frame.

  53. Anand.ady

    Hii
    Plzz help me how to made a dron which is able to carry 500g wet..?

    • Coleman Benson

      @Anand.ady We do not provide consultation / design services, so if you are not ready to research everything, it might be best to purchase a kit, or a pre-made RTF drone.

  54. kaushal ranjan

    Hi sir i want to make drone which is able to carry 50kg

  55. johnson

    Can i make a drone which can be controlled by voice recognition module for indoor activity. How can I programm the esc because i need to limit it by using ultrasonic sensors

  56. satish

    Sir I want to work on the drone project please suggest me for what is the procedure and how to make

  57. S.K Gupta

    Sir, I am confused about the size of the propeler can you plz suggest me the size of the propeler i am going to use a 4 motor which can give thrust of 5N by each motor. Can you plz suggest me the proper propeler size.

    • Coleman Benson

      @S.K Gupta The motor alone cannot give thrust – the 5 pound rating is likely with a specific propeller. Take a look at the motor’s description to see which propeller type is suggested.

  58. yaswanth

    hai
    sir
    I am a student of 3rd be tech
    how to make a drone could you plz tell me drone frame length and weight and required components

    • Coleman Benson

      @yaswanth There is nothing set in stone. The “optimum” diameter is ~500mm for the greatest variety of components and support.

  59. Frank

    What mean the number 4045. I searched and think 45=4.5 inch diameter of the prop. But what means the number 40 .

  60. hemant

    how much rpm needs to take off a dc motor with propellor
    how can I controll the direction of flight by remote
    and how much power requires to give maximum thrust

    • Coleman Benson

      @hemant It’s less of a question of RPM than the combination of propeller specs and motor RPM together. You need a flight controller which accepts RC input. The “power” is a matter of how much current each motor requires to provide a certain thrust. Voltage multiplied by current multiplied by the number of motors would give an idea of the power.

  61. sada y aliyu

    this is very interesting project to mi as a student but
    how can i buy the materials

    • Coleman Benson

      @sada y aliyu We have links throughout the article to places where you can purchase the parts. The series however specifically does not suggest specific components; if you need a list of specific components, you should purchase a kit since the drone is no longer “custom”.

  62. hwang soon yong

    thank you very mcuh, I learned a lot about drone . would you send me your E-MAIL plese. I want tolk to you something.

  63. Jeniffer Lenirs

    Dear Coleman Benson, Thanks, for teaching us.This is very helpful. I follow your blog for build my own drone. I have a question about rotation, It will be supportive if u describe briefly about the rotation. Thank you so much.

  64. Troy F

    Are there any special changes needed to the design to install a gas/fuel engine to the drone? And how large would the blades need to be too lift 200kg? Thank you

    • Coleman Benson

      @Troy F Do you mean a gas multi-rotor drone or airplane? A gas setup is quite a bit heavier than electric, and it takes away from the simplicity, which is why you don’t see many. 200Kg is essentially two people and a child, so you’re looking at something the size of a normal helicopter.

  65. Prithiv

    Hello sir,i am a mechanical student.I want to build my own quadcopter for my first year project.But I am in a confusion of selecting the motor for flight.So please tell me which is the best choice either outrunner or inrunner so that my drone should have a lifting capacity of 0.8 kg.

    • Coleman Benson

      @Prithiv You should really check the motor’s specifications – both outrunners and inrunners can work, provided they have the right specs, with the right propeller at the right voltage.

  66. Prasanna

    Hello sir…
    I like to build a rc helicopter at my home.But i am not clear about the gear mechanism of the main rotor.Can I use normal dc brushed motor for it?

    • Coleman Benson

      @Prasanna We do not really cover conventional helicopter designs here since they have been part of the RC hobby fiel for many years. It’s best to simply purchase an RC helicopter as there are many intricate components needed. Multirotors have become wildly popular because of their simplicity.

  67. Venkata

    I am more concerned about choosing the battery. For some motors the spec sheet says that at 100% thrust the motor draws 23 amps. When we have for such motors how do select the battery pack

    • Coleman Benson

      @Venkata You need a battery pack whose nominal voltage works well with the motors you chose. You then need to verify the maximum discharge current for a given capacity. Most multi-rotor batteries can discharge at up to 20C or 30C, and their capacity (at least for medium sized drones) is around 2-3Ah, meaning they can discharge at the C rating, multiplied by the capacity. For example an 11.1V, 3Ah battery with a 30C rating can discharge at up to 3×30 = 90A. Note that you should NOT be operating at the peak power for too long.

  68. mohd aasif

    Sir ..plz explane me….difference between brushless motor and core motor…???

    • Coleman Benson

      @mohd aasif You mean brushed / brushless and cored / coreless? It’s too much to explain here, but Wikipedia has good articles about both. An online search for “brushless vs coreless” gives many results too.

  69. Mahesh

    how to select the proper required current rating of lipo battery for a bldc motors of 1800Kv ?

    • Coleman Benson

      @Mahesh It’s less about the Kv and more about the current rating for the motor at max power. See the section under “4. Battery” for capacity and discharge rate.

    • Coleman Benson

      @Mahesh You likely mean the discharge rate of the battery – so long as the battery can provide enough current (measured in C) for all motors at max power, you’re fine.

  70. Mahesh

    what is the plus thread of the bldc motor is it cw or ccw…. ?

  71. Mahesh

    how much rating of battery (battery capacity ) should i choose for 1800kv of bldc wt 30A ESC and 10” propeller …?

    • Coleman Benson

      @Mahesh You need to know the current draw of the motor at max power, then choose a battery which can discharge at that rate. The capacity is up to you and will affect flight time and weight.

  72. Aritra

    Hi Sir, I’m a student of electrical engineering interested in building a quadcopter for cybersecurity purposes around the raspberry pi 3 and want to use it as a flight controller and also to control the power distribution board. I’ve zeroed in on a 450mm quadcopter frame;a set of stands for landing;4 1000Kv Brushless DC motors(2.2Kg thrust each);4 ESCs 30Amp each; 4 10×4.5 propellors;searching for a distribution board;3300mAh battery for motors and 5000mAh power bank for pi 3. Please guide me on the parts that I should add to it and I’d like to know how I could turn the pi3-with astropi HAT for sensors, into a flight controller for the project. Any help and feedback is highly appreciated.

  73. Per Egil Møller

    Hi
    I am going to upgrade my hexacopter frame. its base is now 550mm and i going to build a new witch is 800mm. My engines are NTM 28-30s 800kv the drone has 2 4 cells battery. the engine prop test is 12x6E – 14.8V / 276W / 18.7A / 1.20kg thrust. My new frame is about 1500g netto so about 2.5 kilos build i think. Since its a hexacopter i calculated that it will lift 3600g on 50% trottle so it should be no problem using this engines? i can maybe encrease the lift more if i use 14 or 15 inch blades?

    • Coleman Benson

      @Per Egil Møller Maybe, but check to see if the motor you are using has any thrust data for propellers. Larger propellers don’t always guarantee efficient thrust.

  74. Per Egil Møller

    Thank you for your replay, the only prop test of them with value is the 12x6E – 14.8V / 276W / 18.7A / 1.20kg wich i known then to be true, so its should lift fine on 50% trottle and still have a kilo to spare. P cant find nothing more tests of this engine, its from hobbyKing so i have written to them asking for more info since they made them.

  75. Per Egil Møller

    Thank you again, my soulution to this is that i am going to use a special design 700mm carbon frame that folds like and umbrella and it has a folding landing gear. This kitt only weigh 650g so with all i would like to have on it including two batteries i will be around 1700g finnish with gimbal and two cameras. Since the engines lift 3600g on 50% i would have good flight time too.

  76. Alexander

    Hi Sir, I have a doubt. If I plan to built a drone that carry 1.5kg object, what motor and propeller I prefer to choose. Any suggestion?

    • Coleman Benson

      @Alexander The maximum thrust from each motor and propeller (combined), multiplied by the number of motors used, should be double the total weight of the drone (including the payload). Therefore if your drone weighs 4.5Kg, and the payload is 1.5Kg, and you are using a quadcopter design, that means the thrust from each motor should be [(4.5Kg + 1.5Kg) / 4] x 2 = 3Kg. Therefore you would need to find a combination of motor + propeller which provides 3Kg at max thrust.

  77. Gabriel

    Hi
    I need materials that explain methods of how to design propellers according to my performance necesseties of the drone.. do you know where can i find it or any sugestion for starting this type of project?
    Thanks

  78. Krish

    What about the pc cooling fan ?? For a drone… for a model display.I want to just take off

  79. Dom

    Hi Coleman,

    I am designing a drone for use with the ambulance service for my university dissertation. At the moment I know that my drone will weigh around 7kg, and need to achieve a speed of around 40-45ms. I’m currently trying to work out the power/thrust required for the motor and prop sizing so that I can choose the best-suited frame type. Do you have any advice on where to start with these calculations?

    Thanks, Dom

    • Coleman Benson

      @Dom That’s a really heavy drone. If you opt for a quactoper design, each motor + propeller combination needs to be able to lift 1.75Kg at half thrust. You don’t need any calcuations – just look at motor spec sheets for thrust data using specific propellers at specific voltages.

  80. jaya

    its highly appreciable information thanks for provide these important knowledge

  81. Yash

    I want a thrust of min 1kg and i want to use short length propellers like upto 10 to 12cm
    Suggest me the kv of motor and current rating of ESCs and battery amps required
    Please!

    • Coleman Benson

      @Yash You’ll need to read the specs of each motor to know the thrust they can provide with a given propeller. KV does not directly relate to thrust. If you have a quadcopter which weighs a total of 1Kg, the total thrust per motor will need to be 500g. The ESC relates to the motor’s max current and voltage. The battery pack relates to the total flight time you want, as well as the motor’s nominal operating voltage (for the thrust you need).

  82. Oz

    Is it possible to put blades on both sides of a pancake or regular DC motor for a quad copter setup?

    • Coleman Benson

      @Oz Certainly, but to be of any real use, they would either need to be counter-rotating or, better yet, independent. Note that the propeller wash from thr one on top will greatly decrease the efficiency of the one on bottom, which is why it’s not common.

  83. Oz

    Are there electric motors that could turn a 3′ carbon fiber blade?

    • Coleman Benson

      @Oz All DC brushless motors can be used with two, three or four blades – it’s a matter of which best suits your application.

  84. Bruce Saint

    Hi …
    Coleman
    I am surprised this time on my first visit to robotshop.com
    This is an initiative for the best of you in the letter of these lessons …. Thank you and God bless you

  85. Yuriy

    Thanks very much for the article! I’ve been playing around with idea of electrifying some octocopters I’ve been making with my son and would require a very specific set of motors for it to maintain the design of the craft. What I’m looking for is a very low profile motor (height wise). The scale doesn’t really matter, as I could re-print the octocopter in virtually any size, and also have access to CNC (in case I have to modify the motor bell/motor attachments. Would you be able to recommend such a motor/point me in the right direction for further research? Here’s a link to the design: http://yurasklyar.com/multi-purpose-octocopter-mpo-2-cargo-transporter.html. Thank in advance!

  86. Pooja

    How I decided the length of propeller???
    Plz suggest me…

    • Coleman Benson

      @Pooja Always check to see if there are propellers suggested by the motor manufacturer (with thrust data ideally). If not see if you can find similar motors (voltage, Kv, Kt) to get an idea. If that is not available, write to the motor manufacturer and ask for propeller suggestions. If you don’t get a reply, that’s not a good sign. Worst comes to worst, several members of the UAV community have invested in test benches to which they can mount a motor to test with different propellers in order to get thrust data, current draw etc.

  87. darshil

    i am making drone which can lift 2.7 kg . so total weight will be min 4 kg so how much kv motor should i use ? and propeller size ? please guide me ….
    thank you

    • Coleman Benson

      @darshil If we assume you’re making a quadcopter, and the copter’s weight without the payload will be 1.3Kg (including battery, frame, motors, electronics), each motor will need to be able to provide 2Kg of thrust (twice the total weight of the copter). It’s less about Kv and propeller size than about the thrust the motor + propeller combination can provide. Try to find a motor which provides thrust data based on voltage and propeller type and select accordingly. If the manufacturer does not provide this data, sometimes users will perform their own tests and provide results.

  88. wamala Richard

    Mr Coleman I am in a third world country Uganda. I want to make my own drone but there is no material here in Uganda. How can I get a “Printed Circuit Board” and done some materials: motor; battery; dampeners; LED; propellers
    Please help me how can I control my machine can fly in wanted direction

    • Coleman Benson

      @wamala Richard Building a drone on a budget is not easy, and the price of a small commercial drone is often less than just the flight controller needed for a custom drone. Example:
      http://www.robotshop.com/en/hubsan-nano-q4-plus-fpv-quadcopter.html
      A custom drone however can easily cost around $250 USD and can crash on the first flight. The flight controller, motors, propellers, ESCs, battery and charger really need to be purchased – you can save only a little bit of money by creating your own frame.

  89. darshil

    EMAX RS2306 2750KV Special Edition Matte White Bell Brushless Motor 2kg Thrust…is it good for my quadcopter which want to lift 2.7 kg so total weight is 4 kg?..if it is right so please guide me for propeller size and battry size…..help me please

    • Coleman Benson

      @darshil If the max thrust is 2Kg (1762Kg from what we can see online), then four motors give 7-8Kg, which is perfect for a 4Kg quadcopter. There should be data regarding what propeller was used to give that thrust. Please see the section here regarding a battery.

  90. Darshil

    Sir there is not any detail about propeller with motor so please help me that which propeller should I use that will give me 2 kg thrust ….motor I selected but for propeller please guide me sir.

    • Coleman Benson

      @Darshil If the manufacturer indicated that the motor can provide 2Kg of thrust, they really need to indicate what was used to do so, including battery voltage and propeller type. If they do not provide that, you should contact them to ask. We are not aware of any quick method to tell you what propeller to use with a random motor.

  91. SHAMSUDHEEN MARAKKAR

    Sir, I am making a 8*8 cm mini drone. But after making it does not fly. The motors are just rotating but does not go up

    • Coleman Benson

      @SHAMSUDHEEN MARAKKAR It sounds like the motors + propellers cannot provide enough thrust for the weight of the drone. You can post photos and specs for the parts you used on the RobotShop Forum and we can provide feedback.

  92. Wisdom

    Am really interested in building a drone, but I don’t have control panel, is it possible for me to build it and it will work without control panel

  93. tauqeer khan

    hi,
    i want to build to 5kg payload quadcopter, can you suggest me motors other specification ?
    thank you

    • Coleman Benson

      @tauqeer khan For a copter to have a payload of 5Kg, the copter itself will likely weight around 10Kg (guess), so the motors will need to provide around 30Kg of thrust (around 7.5Kg each). Unfortunately we do not carry any motors which offer that thrust at this time (max ~2Kg).

  94. Darshil shah

    i want to make home made ESC please tell me sir how low currunt from arduino convert 30A or more as output in ESC please help me with this sir.

  95. MuhammadSaad

    Dear sir…!
    I want to know about thrust of motors ….i mean to say if i will used 900kv brushless motor for drone project
    And on other side i will using 2000kv motor or more than 200Kv so

    Which brushless can lift up more load?
    More KV’s can lift more load?
    Liw KV’s can lift more Load?

  96. Marcio

    Hi Coleman, help me, please, I wanted Mounted my DRONE F450, I utilize ESC 30A and Motor Brushless of 920 Kv, my Drone weight 1.2 Kg, it isn’t flighting, 2 motors works normal, but other 2 not works well, I already calibrated the motors, but the drone not flight, What Do i Have to do?

    • Coleman Benson

      @Marcio That will take quite a bit of troubleshooting. You’ll need to create a new topic on the RobotShop Forum and list all of the parts you are using, as well as a video of what’s happening. It might be a weight issue, software issue, connection issue.. hard to tell.

  97. rajesh

    Hi, i want to drone lift 2kg of weight. then which kv and v motor and prop and a lipo battery i choose
    reply me sir please. your answer is most useful to me

    • Coleman Benson

      @rajesh It’s less about the Kv, prop and battery and more about the specs of individual motors with proposed props. Normally for multirotor, the lower the Kv the better. You did not specify how many motors, but if it’s a quadcopter, each motor will need to be able to provide 1Kg max thrust.

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