So a year ago, on the 3rd of January 2012, we published the first post here on as we moved from our old site at Back then we were fairly confident that we would release the kit during the first half of 2012. But it turned out the be more work (and more problems) than what we thought. Now as the new year begins we are very confident that anyone who wants a Crazyflie will have one in their hand before the first half of 2013 has passed.

Even though we haven’t made much progress the last two weeks it’s now a matter of fixing the details like packaging, what parts should be in the spare kit and so on. We feel that the hardware and the current state of the software is good enough for release when the kit is released (after some cleaning up). There’s still a long list of stuff that we would like to do but don’t really have the time for. So if you get a Crazyflie Kit and want to contribute there’s a lot of fun stuff still left that we need help with.

Next week is our first Monday meeting after the holidays and then it’s full throttle forward.

Happy new year and thanks for supporting us!

Even though it’s Christmas Eve we managed to sneak away from the celebrations to post the regular Monday post. Unfortunately there’s not much progress to report this week, but we are continuing the planning for the release of the Crazyflie Dev Kit. More and more stuff is being sorted and soon all the details will be in place. As soon as we have a timeplan we feel that we can commit to we will release more information.

Finally we want to wish everyone a Merry Christmas!!

A combination of Christmas preparation, overtime and water leakage took most of the time during the last week so not much progress was done :-(

So what’s the current status in the project? Well, we are still discussing with Seeedstudio on how to start up but most of the things are now in place. We are continuously working on the software/firmware and wiki when we have spare time. Also since we don’t really know how many kits we will sell we are aiming at having a two week pre-order phase before the production of the kits begin.

After one week of flying the new copters we have to say that they are preforming very well. We’ve done a lot of crashes but only had one incident with a bent axis on one of the motors which we fixed by replacing the motor.

We have noticed that using some radio channels in combination with some link speeds causes too much packet drops when the motors are powered. It’s almost certainly the PWM that causes ripples on the power supply and that effects the radio transmission. It was by chance we saw this and changing the channel or speed works around the problem.

Currently we are working with Seeedstudio to sort out the details for starting up but we don’t have an estimate for when it will happen yet. But one thing is for sure, we will go with the rapid-prototype mounts for the first DIY kit. We are still working on the details for the molded motor mounts but since there’s a lot of leadtimes for this it would delay the kit with months and we really don’t want that. Since after the summer we have been using the same design for the rapid-prototype motor mounts and we have only had 2 that has broken.

The plan is to package 1 spare motor, 1 spare motor mount and 4 spare propellers with the kit. There will also be extra spare parts available for purchase.

On Wednesday we assembled and tested all of the kits in the pre-series. We ran though the production tests, that will be used once the kits are produced, as verification. Since we can’t test that they really can fly the test isn’t covering everything but it checks most of the components. One of the units had a solder-bridge between two of the MPU-6050 pins and our tests showed that the unit was faulty. We are glad our tests caught the problem and removing the short fixed it.

The assembly doesn’t take too long and once you have done a few it’s fairly quick. We timed the last one we assembled and it was finished in just under 10 minutes (including fixing errors that were made :-) ). And that time was done by the worst solderer of us! As long as you are a bit steady on you hand it should be ok. It was a really great feeling unpacking, assembling, testing and then directly flying them! We numbered all the units and will track them if there’s any problems. So during the next weeks we will be flying a lot :-). We cross our fingers that they will hold up to what we expect.

The change we did where, connecting the motors directly to the battery and not through the power management chip, turned out great and we could feel the 8% increased power difference (it might have been some placebo effect but it just feels great).

To sum it all up it was a great night and we are really happy with the results! We remember in the beginning when we had to be in a pretty big room to be able to fly the Crazyflie at all and now it’s so stable you can (if you are brave enough) hover it 10 cm in front of your face and then push the throttle and it swishes away!

As for the project progress we are now discussing with Seeedstudio on how to carry on and we are trying to sort out the motor mount problem and some smaller issues.

We’ve also spent some time creating a new page on the wiki describing the hardware. It’s still a work in progress, but there’s a lot of information. We will continue updating the wiki whenever there is time.

Head over to our Picasa albums for more pictures.


Finally our yearning has come to an end, the Crazyflie kit pre-series did arrive from Seeedstudio today! We have not had time to do any extensive testing but so far so good, yay! We did however have time to program and assemble one and it flies really well. It feels like the change we did to route the motor supply directly to the battery and not trough the power management circuit made a difference. The acceleration punch when maxing out the throttle feels stronger. We have uploaded some pictures of the received package. What is still not included in this package are the motor mounts which we ordered separately from Shapeways. The motor mount is one of the last things to sort out before the kit can be ready. We are working on a moulded version which will be much cheaper in bigger quantities but it takes way more time then we expected. We might go with rapid prototyped mounts instead to make it available sooner.

The upcoming week is going to be very interesting as the testing will determine if we can go to the next step!

Since the very beginning of the project we have been maintaining a wiki. At first mostly for internal communication and documentation but more recently we have been focusing on making an easily accessible documentation for the Crazyflie kit.

We now think the wiki is good enough to be released. It is still a “work in progress” but most of the basics are there and it will be updated as we go along. On the wiki we plan to have all information regarding the Crazyflie and other projects. We also intend to complement the wiki with a forum which will be the next step.

The wiki is located at and can also be accessed via the wiki link in the navigation bar.

The last week we have been busy preparing for the presentation we had at the Øredev conference where we talked about the Crazyflie history and design. We had a great time and got to meet some fellow nerds and talk about technology stuff!

All the presentations and keynotes where filmed and can be found on the  Øredev site. So if you have 50 minutes to spare check out our presentation. Or just skip ahead until ~41:00 to see Arnaud stick a Crazyflie in Marcus’ hair…

As for project there’s not much news. We are still waiting eagerly for the pre-series units that will arrive in a couple of weeks.

Last week we received one of the new raspberry pi and we wanted to start doing something useful with it. One idea that came directly in mind was to control the copter with it. As it has 2 USB port it should be possible to use one for the gamepad and one for the Crazyradio dongle.

The Raspberry pi running Debian the operation ended up being surprisingly easy: Just apt-get install python, pygame and pyUSB and we where able to run our old script. By adding pyQT we where even able to run the GUI out of the box (it is still a bit heavy though as the GUI is not yet very optimized when receiving fast log informations). So we just made a “headless” version of the control software, launched it automatically with a udev rule when the radio is inserted and it was done!

We can power the Raspberry pi with a USB battery and we now have a small portable ground station for the Crazyflie. We have also proven that our PC software tools are easily portable to other architecture thanks to Python and all its libs. Currently the software is tested on Windows and Linux (x86 and ARM), but it should also work on MAC.

Raspberry PI controlling the Crazyflie

While we are waiting for the pre-series to arrive, which hopefully will be within 4-5 weeks, we have tested this idea we have had for a while. On the Crazyflie PCB we placed mounting holes in each corner for the possibility to add e.g. a landing gear, canopy or maybe a protective frame. The holes are about 0.9mm and plated so it is possible to solder something in it and a protective frame made of piano wire would be a good candidate.

We bought a couple of 0.8 mm thick 1m long piano wires at a nearby hobby store and got to work. On the first try we bend the wires into the shape solely by hand and it didn’t look or work well at all. We figured there must be some better way! And after searching the net we found this site explaining how to make your own DIY springs of different types. We however needed a circle with a much bigger diameter than normal springs use so it took us a while to find a tube with the right diameter to bend it around to get the right size. We found out that when bending the piano wire around a tube with the diameter of 20mm it ended up at about 55mm which was close enough to the 60mm we needed. Piano wire is a bit hard to solder but with plenty of solder flux it works well. We are pretty pleased with the result!

The piano wire frame itself weights about 3.5-4g so it is within the acceptable payload limit. The flight characteristics is changed a bit making it more controllable but less agile which is perfect for beginners. We have tested throwing it in the ground and crashing it several times and the Crazyflie just bounces so it works great. It might even be possible to go to a smaller piano wire diameter to save weight because now the frame is very stiff. Next step would be to come up with a design that could be attached/detached without soldering. It should also be cheap and easy to manufacture.