Articles for October 2015

How much power is needed to hover ? (REVISED!)

This article is a theoretical venture that aims to answer a series of practical questions, such as:

– given a certain electrical setup that can generate a certain power, what is the maximum thrust that we can achieve ?

– can a human-powered aircraft be built ?

– can I tell the expected thrust generated by a copter simply by knowing the power it consumes and vice-versa ?

– are larger propellers really more “efficient” ?

– which multicopter configuration is more efficient:  tricopter ,  quadcopter ,  hexacopter or octacopter  ?

– I heard that for every gram of mass I add to my multicopter, the flight time will decrease by 1 second, can you put any sense in this ?

– and many more…


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Here Are the 25 Members of the Drone Task Force

The Federal Aviation Administration has announced the 25-member task force that will advise the administration on its proposed drone registration rules.

The FAA says the group’s co-chairs are Dave Vos of GoogleX and Earl Lawrence, director of the FAA’s Unmanned Aircraft Systems Integration Office.

Amazon has two members on the task force, joining others from 3D Robotics, DJI, Google, GoPro, and many others.

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Automated Precision Landing on a (stationary) Boat

How many copters did we sink? 🙂 Check the video above. The development of Precision Landing hardware and software has progressed since our last blog post. The existing controls code has been added to master in APM:Copter (i.e., V3.4-dev). The two demo videos included in this post were produced with a modified version of APM:Copter V3.3 (similar to the master code). This documentation (link) should provide some clarification for advanced users who want to experiment with the features. And the relevant APM Wiki link is here: link

CONTROLS: Keep in mind that the Precision Landing controls code will probably undergo significant changes in the future. As it stands, the sensor detects the target and outputs an ‘angle-to-target’ reading. The roll/pitch of the copter is subtracted from these readings, assuming the sensor fixed to the copter frame. Coordinates are transformed from body-frame to earth-frame. Then, the altitude of the copter and angle-to-target in earth-frame is used to calculate the distance-to-target in the ‘x-y’ plane. This distance-to-target is used to re-position the copter over the target. One limitation of the current controls method is that the relative altitude wrt the target is required. Fortunately, there are good range-finder options available now.

VARIABLE LOGS: One helpful improvement is that the Precision Landing variables are logged, enabling much more effective post-flight troubleshooting and analysis.

bX/bY: Angle-to-target measurement in the body-frame reference BEFORE accounting for roll/pitch of copter.
eX/eY: Angle-to-target measurement in the earth-frame reference AFTER accounting for roll/pitch of copter.
pX/pY: Calculated distance of target from copter in earth-frame. Note that the distance calculation depends on the altitude measurement. Also, the altitude variable in this particular instance is range limited, such that a negative value or very small value is not used to calculate the position offset.

SENSING: There are improved sensor system options for professional users (MarkOne). There has been significant interest from industrial users/developers regarding the development of automated UAV systems: automated charging, safe automated landing, copter-on-vehicle landing, etc. The boat landing demo video is useful for demonstrating the improved reliability of the sensor readings, which is critical for professional use in automated systems. 

Some of the logged sensor readings from the boat landings are plotted below. The green line indicates the altitude of the copter. The red line (‘bX’) indicates the angle-to-target measured by sensor in the x-direction, relative to the sensor (fixed to the copter). We no longer have issues with false detections, even in challenging operating environments. False detections which would be indicated by immediate, large changes in the ‘bX’ value. (see an example of false detections here: link).

INTERPRETING LOGS: When the LAND mode is initiated, the copter begins moving toward the target, driving the angle measurement toward zero. Oscillations in the angle measurement are typical. ‘Flat lines’ in the bX/bY plot indicate periods of time when no target is detected. This may due to the target being out of range of the sensor, or out of the field of view of the sensor. In this test (below), the MarkOne beacon is detected at distances of over 15 meters.

Toward the end of the landing, the angle measurement may increase significantly and/or turn into a ‘flat line’. A flat line is expected if the copter does not land directly on top of the marker (i.e., 5-30cm away). The marker can easily escape the field of view of the sensor during the final ~10cm of descent. Also, the detection angle can easily become very large when the sensor is very close to the marker.

DEMO 2: Here is a demonstration with 5 consecutive Precision Landings. Below, you will find the following content:
->Plot of logged variables for 5 landings
->Plot of logged variables for a single landing

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FAA/DOT UAS Registration – A Very Short Window to Comment

Hi All,

We have a very short window of opportunity to comment on the FAA’s proposed registration process.

I have sent in the following comment which you are welcome to copy, edit, do whatever you want with, but I think it realistically presents a decent case for moderation and common sense on the part of the FAA.

(Yeah I know good luck with that!)

In any case, here is my comment:

I understand the need for increased accountability when dealing with UAS of all types and some sort of registration process if appropriately limited can provide the access needed to better assure safety for everybody.
But there are some very important issues that should not be ignored.
There is a very large hobby market already in existence including RC Planes and toy quadcopters with many tens of thousands of people already owning and flying.
And so far these have been flying for decades with a very good safety record.
There are several classes of remotely controlled flying things that represent little or no real hazard to anyone, based on light weight, low mass and short range.
Individual UAS registration seems excessive, I personally have over 20 RC planes and quadcopters and registering each of them would be an unnecessary burden and serve no practical purpose.
So I propose that you consider the following.
1. Register “pilots” not UAS and make it free or very cheap in order to encourage compliance. Provide a pilot registration number that is required to be affixed to each of the “pilot’s” qualifying UAS.
You could even provide some legal obligations information in the course of the pilots registration process.
This is much less ponderous than trying to deal with huge numbers of each individual UAS.
2. Set some reasonable limits on what is to be defined as a UAS.
At a minimum their should be a weight limit below which registration is not required.
For Multicopters I would suggest 1 Kilogram as this is a common cutoff in Europe and the UK but I realize that 1 kilo could still be dangerous and even 1 pound could be OK and would represent very little hazard.
You could also consider exempting specific examples of both quadcopters and fixed wing UAS based on specific construction benefits such as foam construction, short range and low mass.
It is my feeling that if you do not exempt toys and small UAS you will create an unenforceable and ponderous mess and damage the existing hobby and toy markets severely for no reason other than that you can.
I sincerely hope that you choose to take a conservative and reasonable approach to this that truly serves all of the American Public.

You can send your commentst in via the link here:!documentDetail;D=FAA-2015-4378-0022

3DRs link on this weeks download doesn’t work and is already closed for some reason, but this one is still open (as I write this anyway).

Only have a few days to comment (probably don’t want a repeat of all those comments they got last time).

Best Regards,


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GoPro’s Unreleased Drone Already Shoots Great Video

GoPro’s been working on this camera thing for a while now, so you’d expect anything it makes to capture great footage. This video is still impressive. GoPro’s launching a drone in the first half of next year, and released a two-minute video captured with a prototype. “The footage has not been stabilized in post-production,” the video says, and if that’s true GoPro’s got a winner on its hands.

The color and dynamic range aren’t the point—the footage is shot on the Hero 4, which you can already buy. What’s amazing is the perfect, almost dolly-like stability of the shots of an idyllic farm and a journey through the forest. The sleepy guitar music, though, has nothing to do with the drone. It’s just nice.


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Erle-Brain 2, the newest Linux autopilot from Erle Robotics

Since we made Erle-Brain we’ve got a lot of feedback on what’s most used and useful for users. With this in mind we are happy to announce we have released a new version of our brain: Erle-Brain 2, a more powerful unit, smaller, faster and cheaper brain for building robots and drones.


Erle-Brain 2 ships with a cost of €199, includes a quad-core Cortex-A7 with all the sensors needed to create copters, rovers, planes or even hexapods. It includes integrated optional 1080 HD 5MP camera, Wi-Fi, Bluetooth, 3G/4G networks, USB, Ethernet, I2C, HDMI and UART.

The weight of the whole system is 100g and the size is a bit smaller than his predecessor with 96 x 70 x 25mm.


Some specifications regarding the sensors included:

  • Accelerometers: MEMS digital-output triple-axis accelerometer with a full scale range of ±8g (or alternatively ±16g) and integrated 16-bit ADCs

  • Magnetometers: MEMS triple-axes 16 bit (15μT/LSB) with a full scale measurement range is ±4800μT

  • Gyroscopes: MEMS triple-axes with a full-scale range of ±1000 (or alternatively ±2000) °/sec and integrated 16-bit ADCs

  • Barometers: digital pressure sensor with 10 cm resolution



For those of you interested. Erle-Brain 2 has been built on top of the Raspberry Pi 2. This decision has been made mainly due to its popularity and existing support for this board already. We are looking forward to collaborate with other existing options based on this exact same board

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Dashboard for Agriculture Drone Data: Early Preview 

First I would like to Thank you to this wonderful community here, who have helped us learn latest and greatest about drones, agriculture in specific. Past several months team at Harvesting have been working on building a innovative dashboard for farmers, to provide them data driven insights. This dashboard is now available for early preview for this group and would like to get your feedback. Tell us how we can make it better My email is [email protected]

How to sign-up for free public preview?

Visit and click on ‘free trial’ button

What functionality this solution have currently?
Once you sign-up for free trial, you would be able to :

  1. Upload and manage NDVI, Ortho processed imagery from drones.
  2. Create time series of your imagery to see how its changing over the period of time.
  3. View satellite image of your farm.
  4. See hyper-local historical weather information as well seven days forecast.
  5. See water-stress in your area (mostly useful for rain harvested farms)
  6. Analyze crop-growth for following supported crops Barley, Canola, Cotton, Oat, SugarBeet, Sunflower, Wheat, Corn
  7. See soil information, a pie-chart which shows what type of soil you have on your farm.

What functionality coming in future?

There is a lot in our pipeline, but our primary focus would be to make it easy for agriculture drone operators/farmers to easily manage and share their data online and get meaningful insights on click of the button. Some of things we are exploring includes auto-detection of certain pests, digital classification, detailed field health reports, etc.

Thank you so much again, please visit and sign-up for free trial. Keep your feedback coming.


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VR Brain 6 Core : Virtualrobotix upgrade and reinvent the oem Flight Control : Preview

This is the first preview of Next Gen STm32F7 flight control by Virtualrobotix.  New core , much power and a reliable solution based on industrial micro controller. 

A new oem and hobbyst platform with full support for :

  • Copter 
  • Helicopter 
  • Plane
  • Rover
  • Boat

This new form factor is simple fast prototyping platform for your own custom design but a reliable design for your final solution. The standard version of VR Brain core 6 support classic STM32F4 micro controller.

Will be available in mass production Q1/16 prototypes for our OEM customers will be available in December 2015

If you are not already our OEM partner and are interested to the product  contact me at [email protected] 

Suggestions are welcome.



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All new Hubsan H107D+ With Alt. Hold.

Hubsan announced it’s new models for their mini quadcopter product range, one of them is H107D+. It’s announced on January,however; it is not fully available neither online or on site, not even a curtain release date. Currently only a UK Company sells it online and on site. I got mine from their Peterborough store with price tag 169 GBP. 

Unlike H107D, D+ has a different control mechanism. Throttle stick is centered just like Aileron/Elevator stick. To fly it you first arm it with a stick configuration than you raise the Throttle more than %50 percent. As soon as you release the Throttle stick it tries to hold it’s altitude. As an Engineer i could not stop my self to open and see the electronics inside. From the photos above it has a outstanding build quality. As you can guess barometric pressure sensor is covered with foam to read more accurate pressure sensing.

I had i couple of flights with it both indoors and outdoors. Battery lasts ~6 Min,which you charge it via usb on quad.It has a special battery and battery compartment, no more plugging cables. I like this compact military design. Indoor flights are not as perfect as 107D or X4 because alt. hold mode can’t hold the altitude rock steady, it oscillates within 20cm up and down at a low frequency to manage it’s altitude . On outdoors, it’s much more stable and fun to fly. Video feed range is very good, it can hover in a point where you can barely see it without loosing transmission. 

You can start stop video recording and take photos from TX. Video quality is good day/night (with 720P resolution).My overall opinion on D+ is it requires firmware update to fly much more stable and solve rare bugs, i hope that usb connector build this in mind.

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My Quadcopter- Arris X-Speed 300

Hey guys I started out building my first quadcopter with a plastic frame, 1900kv motors, 15A ESCs, DJI NAZA flight controller, and some LEDs.

Everything was going well until I decided I wanted to put my gopro on and have FPV at the same time!  I went with the Fatshark goggles, 600TVL HD camera, and an Immerse RC 600mw Transmitter.  Then I crashed 🙁

Currently I did a new build with the ARRIS X-Speed 300 Racer Carbon Fiber Frame, Emaxx 2300kv motors, and I reused the DJI, 15A ESCs, and the LEDs.  Also threw on the same FPV gear.

I just started out with the multirotors and so far its been a fun ride.  I can’t wait to see how this new one performs.  Glad to be apart of this community and DO please let me know if you have any tips / tricks / suggestions on how I can improve my build!

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