21

A stable system is one where there's a force that pushes the system back towards it's original state when the system is moved from its balance point. For example, when the driver gets into a car, there's more weight on one side of the car than the other but the car doesn't flip over. The springs on that side of the car compress and push harder on the wheels....


17

One practical advantage is increased ground clearance, reducing the likelihood of a prop strike on landing or take-off. Aerodynamically, a pusher1 design can be less efficient because the propeller is spinning through the wake of the fuselage - this results in 'lumpy' air, causing vibrations. I don't have exact figures, but I've heard anecdotally that this ...


15

Any vehicle yaws (i.e. turns) by having a net torque applied. What's interesting about a quadcopter is not just how it yaws, but how it yaws and doesn't roll, pitch, or climb at the same time. To understand how this works, we need to briefly look at the math. We'll use a plus configuration, but really any mutirotor configuration works. The thing to keep in ...


14

There are several things that can be causing this with different likelihoods. The first thing to check is - are your propellers on correctly? It is an easy mistake to make and always worth a check. The next thing to check is that all of your motors are working correctly. Start by spinning each of the motors by hand and see if anything feels obviously wrong,...


14

It sounds like you've encountered what's called "vortex ring state", when a rotorcraft descends into its own wake -- essentially, a self-created downdraft. There are two ways to escape from such a situation: Power out of it. Climbing out of the craft's wake vortex requires about twice as much power as hovering, so while most full-sized helicopters can't ...


14

Having Googled the S49 drone, it appears that your drone uses ‘headless rth’. This means that instead of using GPS, the drone goes into ‘headless mode’ then pitches backwards towards you. Unfortunately, due to the nature of how this works and the inaccuracies of the accelerometer, this process is rarely accurate. I don’t know of any way to fix this as it ...


14

Expanding on @Kralc's answer: Here's a study (unfortunately behind a paywall) that I'm going to copy key parts of below: The hexacopter was mounted on a load cell test stand, and data were collected in the University of Michigan’s 5 × 7 ft wind tunnel over different freestream flow speeds, motor thrust percentages, and hexacopter angles of attack. To ...


12

There are several things that can be causing this with different likelihoods. The first thing to check is - are your propellers on correctly? It is an easy mistake to make and always worth a check. The next thing to check is that all of your motors are working correctly. Start by spinning each of the motors by hand and see if anything fella obviously wrong,...


12

Background Stiffness, oscillation, and vibration damping are separate concepts but all somewhat relevant to the question. Each affects flight dynamics, and each is (somewhat) a function of material choice. For example, titanium is very stiff, and it rings like a bell. CF is very stiff, but it rings like mud. Aluminum is in between. Stiffness Stiffness ...


11

The yaw effect created by the same effect that would cause a helicopter to spin if it didn't have a tail rotor. On a multirotor, half the propellers spin clockwise (CW) and half counter-clockwise (CCW). This 50/50 split evens out the rotational forces for straight and level flight. To yaw, these forces need to be unbalanced. To spin CW for example, the CW ...


11

Yes, you actually can! There are a couple of options for the Betaflight firmware which are mostly plug and play. OpenTX Lua Scripts Radios running OpenTX can use scripts written in Lua to control these parameters with the radio's scroll wheel and buttons. Please see @PaulKendall's answer for an explanation of how this method works. Betaflight OSD If you ...


9

"Hot quadcopter" is a bit broad of a term, a lot of things can be hot in there. Maybe it's the VTX, then it's normal, they can get hot up to 80C. You might want to use a heatsink though, depends on your VTX. It might be the Flight Controller's CPU itself. For example, F7 processors can get hot up to 70C It also might be motors. If you can barely touch them ...


8

Checking Direction In Betaflight you can have your motors spinning either props out or props in. The default is props in (towards the body of the quad from the front and back). Be aware other flight control software such as FlightOne and Kiss have different defaults. Default Direction Reversed Direction If you are running props out, make sure you flip ...


8

According to this paper: pitch and roll control authority is up to about 30% greater for the cross-configuration since all four (as opposed to only two) rotors are used. However this is a bit academic as you often combine pitch and roll in normal flying, or fly at an angle, so it only matters if you want to do the fastest possible flips or rolls. For most ...


7

If the battery was low enough, voltage sag during flight could be enough to cause the loss of thrust. When the quad has enough time to sit, the voltage may bounce back enough to take off for a brief period of time. Lipo Batteries are near empty when they are around 3.3v per cell. And to keep from damaging them, they should not be brought down even that far....


7

It’s called Airmode. It keeps the motors in a constant idle state, even at zero throttle. This gives you pitch, roll and yaw authority even when you are upside down. You can enable it in the configuration tab in Betaflight. You will notice that your props may try to spool up even when your quad is just sitting armed on the floor, but this is called I term ...


7

I have found that the simplest and probably one of the safest ways is to use a compressor (alternatively a compressed air can will probably work), to lightly blow away the dirt. This works especially well if you just want to get rid of grass straws or similar. If you want to more thoroughly clean something Joshua Bardwell has a video on how to clean a motor,...


7

This design is to prevent unwanted yaw when moving, or vice-versa. Consider the following two actions: When a quadcopter yaws, it does so by creating a speed difference between the opposite-rotating rotors; creates a torque that rotates the quad. When a quadcopter moves left/right, it does so by slowing all the motors on one side of the frame and/or ...


7

The trick is speed. The reason why multirotors don't lose (very much) altitude while performing quick mid-air aerobatics is because of the speed of the move and the skillful management of throttle by the pilot. You're correct in presuming that a multirotor performs a flip by changing the speed of the motors on each side of the craft. Freestyle pilots ...


7

Inherent stability is a concept from aeronautics – it is the tendency of an aircraft to return to an equilibrium when the controls are released by the pilot. Quadcopters are not inherently stable. Say, you have the quadcopter rolling to the right: (image source) A quadcopter requires active counter manoeuvres to restore it to a stationary hover: (...


6

I would personally recommend using isopropyl alcohol or mostly any other type of alcohol and using it with a cloth to gently clean the drones shell and propellers off any marks/stains. This shouldn’t damage the drone. As well as this, a microfibre cloth could also work well.


6

Airmode and idle up both seek to increase a control authority and stability during ultra-low throttle moves. In normal flight, when the pilot commands the multirotor to pitch or roll (cyclic), the flight controller responds by increasing thrust on one side of the craft and decreasing thrust on the other side by the same amount proportional to the cyclic ...


6

I think the Cidora SL5-E is a very good choice. What you need to look for is the "BNF" suffix in the description which stands for "Bind and Fly". In that case a receiver is already built in. On the iflight website you can select this option. If you have the choice, it's best to select the r-xsr because it comes with telemetry. If you are ...


5

I've got a paintbrush in my flight kit which I use for removing chunks of mud/grass from my quads so I can keep flying on the day. If they get really dirty, I use a toothbrush dipped in alcohol once I get home. If they are really bad, I pull them apart and go over each part with the toothbrush and alcohol.


5

I've had this recently with 2 different BNF's. One I had the props on the wrong way! The other I needed to recalibrate the accelerometer. You can either use Betaflight to recall, or the stick commands (Google them and keep a copy in your flight bag).


5

Additionally to the options listed above, looking into whether or not: You may have a reversed or upside down prop Motor spinning wrong way FC board orientation isn’t what it thinks it is


5

I've had success cleaning grass from drones using a damp cloth (just water.) You shouldn't need chemicals to get grass splatters off if they are fresh, but if you do use them then try it on an inconspicuous part first in case it does cause discolouration. Make sure the battery is removed to prevent damage should any electronics get too wet, and let the ...


5

For non-electronic parts (frame, camera case etc.) I'm using just those "cotton ear cleaning sticks" and plain water. If you just wet the dirty spot, wait a minute until the water softens the dirt and then you can just easily wipe it off. And for electronics I would use same technique but use alcohol like other answers recommend.


5

Altering the location of the CG (center of gravity) also changes the CM(center of mass) because the force of gravity acts roughly on the CM. Normally, the motor arms are equally sized so that all motors have equal control authority and all contribute equally to providing thrust while in level flight when the CM is close to the center of the multirotor. ...


5

TL;DR: You wouldn't want to be responsible for the design of such a project. :) Between the environmental constraints (atmospheric pressure, temperature, etc.) and physical requirements (extreme radiation tolerance, etc.), this would be an incredibly difficult thing to make. Believe it or not, there is actual flight hardware being prepared to do something ...


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