Welcome to NORB!
NORB has returned!
After two years of unscheduled hibernation, I’d like to say that the NORB blog will be back in service. Having just completed my first year of Aeronautics and Astronautics at the University of Southampton, I’d like to revive the blog but set it on a slightly different trajectory.
Now that I’m fully immersed in the course, it seems a logical step to post a little more about what I’m doing in the aerospace world and document some of my latest engineering projects. Keeping in mind, of course, that all of this has grown from the HAB community, a large portion of this will be relevant to HAB. Since aerospace encompasses HAB and other my other interests, this is now going to be the NORB aerospace blog!
A year ago today I heard I'd been succesful in exceeding my A*AA offer to study Aeronautics & Astronautics (MEng) at the University of Southampton. This seems like a good day to kick off the new blog.
13th August 2016
A GREAT SUCCESS!
Yesterday was the first flight of our first ever to fly AVR based circuit board, and WOW did it perform well. A massive thanks goes out to every single tracker who helped us follow the progress of NORB 2 yesterday! You're all awesome!
Burst altitude = 36.1KM
After troubleshooting sound problems only minutes before launch, we were all set for launch of NORB's second flight. Armed with a GoPro HD Hero 3, NORB board version 3 (1 and 2 never flew because I kept making them better), and a backup pava in a ball named BRON, we were ready to take to the skies. And had it not been for Steve Randall assisting us hugely with the filling and launching and supplying of all the kit necessary for flight, we wouldn't have been going up. Thanks Steve!
And off she went, climbing at a steady 5 m/s attached to a Hwoyee 1200g balloon filled with hydrogen gas (we had 2 fire extinguishers on hand!) The pictures speak enough words themselves:
Above you can see BRON, our backup tracker, in the distance
Unfortunately, the GoPro didn't survive to shoot the landing, but this flight was still a huge success! After writing a quick Python script to turn the data on the NORB board into something useful, here was the result:
You can see from the above temperature graph that there's no way an exposed GoPro can survive -25 degrees celcius unless it's in its trusty case (and we thought it would overheat!) The graphs also show a very clear increase in humidity as the payload descended through the cloud layer and into the moisture of lower earth's atmosphere.
When NORB hit the ground, it was only 30ft from the A14! Struggling to find access to NORB's final location, I received a call from the famous Mr Upu. Having had Mr Upu's invaluable directions, we were able to find it much much sooner than we other wise would, if we'd have even found it at all! So thanks again Anthony! More pics to come...
So all in all, a very very very good, successful and extremely exciting day out! Now, what's the next project on my list? ;-)
NORB 3 board is about to fly, NORB 4 board is on it's way!
Having had sufficient time to do absolutely nothing while we wait for the British weather to relent, I was eager to get on to a new exciting project. I've been involved in the HAB community for just over a year now, and in my time here I have seen a huge variety of wonderful projects, including long-range floaters such as those that Leo Bodnar famously (perhaps infamously) sends up very regularly. You can probably see just what I'm about to attempt to get myself into...
After some preliminary research and several conversations with the masters (particularly Anthony Stirk), I had a rough idea of what I wanted my board to do and how I was going to do it. Then it was a case of reading the datasheets for the new components I'd be having to use very thoroughly to figure out exactly how the circuits needed to be laid out. My main components list was finalised:
- LTC3526 Regulator
- SI4064 Radio IC
My reasons for choosing the above parts are simple. The ATMEGA328P has been used on all previous NORB board trackers due to its brilliant suitability for HAB trackers. With the ability to be operated at a wide range of speeds (for HAB typically 2-8MHz, or 16MHz if you like to drink charge), and the reasonable number of IO pins, it can be seen that the ATMEGA328P microcontroller is well-suited to the job. Furthermore, the MU package as being used on NORB 4 is the smallest of the lot which works in my favour when designing a tracker that is super light and super power efficient.
The LTC3526 voltage regulator is very similar to the TPS61201 voltage regulator used on NORB 3. Both are step up converters and both are super efficient. But having compared the datasheets and spoken to Mr Upu, it was proven that the LTC3526 was the more efficient of the two, which makes it the better one for NORB 4.
Image from Silicon Labs
The use of the SI4064 radio IC allows me fundamentally to create my very own radio circuit, as opposed to using the commonly used Radiometrix NTX2 transmitters and others of the sort. This means I can avoid the added weight of the casing of an actual ready-made radio, and I can understand how the radio circuit actually works instead of taking it as a given. The SI4064 is configured over the SPI bus and can be used for DominoEX and THOR by toggling a single GPIO pin from the microcontroller. THOR might be a tad complicated for me just this minute, but DominoEX is well within my capability for NORB 4's downlink. The use of DominoEX means that the signal will be particularly resistant to any noise as it passes over various spaces on its journey. Since NORB 4 won't be floating at high altitudes, this is a good thing to have.
And here she is, all complete:
Since this board consists of a mixture of 0603 and 0402 sized surface mount components, I have been informed that it is a wise move to use a stencil and oven as opposed to hand soldering these on. Being able to slap the components on the board with some solder paste, let it bake for a few minutes, and then pop it out and voila, very much appeals to me I must say. And that is why I have also designed a stencil to go with the board.
NORB Launch postponed...
After many weeks of weather-related despair, it appeared as though this weekend we'd have our chance. But unfortunately, the British weather won't relent just yet. We're now looking at a possible launch in early April. Hopefully NORB 2 can finally get off the ground with slightly better winds and an alternative launch site further away from the North Sea, Ross-on-Wye. All systems are checked and ready to go including the recent addition of our new GoPro 3 Camera. All that's left to do now is route it into our lovely box:
In the above image you may notice the £30 Canon Powershot armed with CHDK. With our recent addition of a GoPro, you'd have to be pretty much an idiot to fly both cameras up there when one is heavier and more power thirsty than the other and is of less quality. So soon, the Canon compartment will be modified to suit the GoPro.
This tiny foam ball will act as our lifeline, just in the unlikely event that the NORB board inside the main payload designs to go off the rails. After all, with a GoPro on board, who wouldn't want to find their payload again?
So the plan, a 1000g Hwoyee to be filled with a nice amount of H2. Having initially settled on the larger Hwoyee 1600g balloon, I recently realised that the bigger balloon was more expensive to buy and even more expensive to fill than the smaller 1000g Hwoyee, where altitudes of around 30km can still be achieved. Since the primary aim of NORB 2 is to test out the new NORB board tracker, any nice footage above 25km is a bonus!
Current hourly predictions for our launch site are a little scattered at the moment, but we really cannot form a really idea of the likely winds until a minimum of 3 days before. We're keeping our fingers crossed, but we're hopeful NORB 2 will fly on Saturday 15th of March.
The box is complete!
After much hot glueing and one 1/4 wave antenna later...
After some careful designing and precision engineering in my Granddad's garage:
The NORB 2 box was born...
It's not quite finished, but only minor tasks have to be performed on this stunning piece of foam architecture if I do say so myself. We need to drill a small hole right through the centre of the box to allow coaxial cable for the 1/4 wave antenna to go from the NORB board SMA connector, to our antenna radials on the bottom of the box (still need to do that too). Then, we're just going to route some small cutouts to set the battery pack and NORB board neatly into the box so they can't move before glueing up the walls and bob's your uncle.
The foam has arrived and the batteries have saved me...
I'm delighted to announce that after running the camera non-stop on two fresh Lithium AA batteries, after 2 hours 30 minutes, 99% battery power remained. We are go for launch! Well, box design...
Yesterday evening just before I was due to go out, a nice sheet of 25mm thick blue styrofoam arrived:
I have started the designing of the box, and this time it really will be like a box. Our last payload was essentially a sandwich, with two pieces of foam being squished together to contain our vital components. This design should be more sturdy and hopefully a little more reliable. There'll be more on the box and antenna design to come on separate pages on the site.
In recent weeks, I have been tweaking the NORB board here and there to the point where I can now sit back and relax and get ready for a HAB flight hopefully next month. This week I made some slight changes to the code:
Since it's creation, the NORB board has been transmitting over the radio everything it can. By that I mean it has been transmitting temperature, voltage, humidity, as well as all the standard information you transmit as basic telemetry. By definition, a longer datastring coming down over the radio link has a higher probability of a decoding error.
To avoid this issue, I have taken the decision to record all our extra data such as humidity and voltage to the micro SD card, while transmitting only the basic telemetry along with a temperature field, and can now say that this is working good enough for flight.
What does NORB now do perfectly:
- The board sits quietly on my window ledge until it gets a GPS lock. As soon as it gets one, it processes it to check that its all valid data.
- Then, it takes some readings from the temperature/humidity sensor and reads the voltage across the cell from an analog pin on the microcontroller.
- It appends the new data onto the parsed GPS data and stores it as one string called the "log_datastring" and transmits one called "send_datastring."
- The datastring is split up into bytes, then bits, and is transmitted down over the 434MHz radio link back down to Earth where data can be decoded live using some software called dl-fldigi.
After searching through the many different camera options, we have settled on the Canon Powershot. To read more about power issues and CHDK, head over to NORB 3's project page.
For HAB, I and many others opt for the Energizer Ultimate Lithium AA or AAA batteries. Unlike most alkaline batteries, these beauties have a much lower rate of voltage drop over time as can be seen on the graph below:
Now it says on Energizer's website that these batteries *can* last up to 9x longer than standard alkaline batteries in devices such as digital cameras, depending on the camera. So I took my 29 minutes on normal batteries and multiplied it by 7 to account for a slight safety factor which resulted in a rough estimate of 200 minutes or 3.3 hours!
After the batteries arrived and I tested this, the batteries worked flawlessly and used only 1% power after 2 hours 30 minutes!
So, we're good to go:
Balloon: Hwoyee 1600g
Gas: H2 (Hydrogen Gas)
Absolute Max Total Weight: 1KG
Target Altitude: 37KM +
Launch site: Elsworth, Cambridge