Babbage’s big jump: the aftermath

If you were following the live feed and our live tweets on Saturday, you’ll know that Babbage the bear’s attempt to beat Felix Baumgartner’s stratospheric parachute jump with a couple of Raspberry Pis was a bit of a curate’s egg. It was a very blustery, cloudy day at the launch site, and while Babbage made it into the stratosphere (beating the world record – also held by Dave Akerman, who was behind this weekend’s launches – for highest pictures transmitted live from an amateur device), he did not separate from his platform properly, so rather than leaping into the void, he plummeted, platform and all, when the balloon burst at 41.109km, and fell to earth under the tatters of the balloon. We were able to use GPS to work out where he had landed (in the middle of a barley field somewhere in rural Berkshire), and retrieved him. Here are some pictures from Saturday (thanks to Anthony Stirk for the pictures which I didn’t take – you can tell which ones they are, because I’m in them):

The day opened with a bacon muffin. And a radio mast.

It was a VERY blustery morning. Here Dave struggles manfully against the wind, which is trying to blow our balloon into a bramble patch just after filling, before the payload had been attached.

Despite planning every minuscule detail, Dave forgot to make a capsule for Babbage’s parachute. Fortunately, there was an empty Smarties tube in the back of our car.

Dave recorded a time-lapse video of the preparations for launch (and selected a doozy of a frame for the still you can see now – not impressed, Dave):

We ended up using three lines to stabilise the balloon for launch.

Babbage got away safely. Dave does a happy dance of glee.

Here’s the launch in all its very windy glory:

We retreated to Mission Control (Dave’s house) to monitor the flight.

Back to Mission Control (Dave’s house) to watch data coming back from the payload.

Both the capsule and Babbage himself were equipped with Raspberry Pi camera boards. While waiting for the balloon to burst, we were able to watch images like this streaming back from the stratosphere.

Dave’s currently uploading all the pictures taken from both parts of the payload to Flickr.  An hour’s driving towards a GPS location and a half-hour’s scramble through hedges and fields later…

We had to climb through a few thickets full of brambles and nettles from the car before we could get to the barley field where Babbage landed. Dave went to get the wreckage alone so we didn’t disturb the farmer’s crop. As you can see, the separation hadn’t worked – all the bits of the payload are still attached to each other.

And this resistor is why. A program trips in the Pi at 39km up and sends current through it, which is meant to heat the whole assemblage up and melt the nylon cord. It has 5 seconds to get from -50C to +200C – which wasn’t enough at 39km up. As you can see, no melting occurred. For the next launch, Dave added more batteries, which worked like a charm.

Back at the car. If Eben had hair, it’d look like he’d just crawled through a bush too. (Mine looks like I’ve just crawled through a bush because I’ve just crawled through a bush.)

So Dave, dissatisfied with the performance of that 5p resistor, decided to launch again on the Bank Holiday Monday. (We didn’t join in this time, largely because it’d have meant another drive of some hundreds of miles.) And this time, the separation worked like a charm.

Dave’s second attempt on Monday ended up being covered by the BBC, the Independent and the Register, so you can read all about it there. He’ll be being interviewed on BBC Radio Berkshire this evening from 4.30pm for a few minutes – and the BBC is also sending someone from Click (the radio edition) to chat to him later on today. He’ll also be updating his own site with a report on the flight later on – check back soon!

If you want a Babbage of your very own, whether you want to send him into near-space, or whether you just fancy something to cuddle, you can buy him at the Swag Store. All profits on Pi merchandise go straight back into funding the Raspberry Pi Foundation’s educational work. And Babbage is just the right size to be hollowed out and filled with a Pi, batteries and a camera board, and just the right weight to be put under a balloon and sent into the stratosphere to take some amazing pictures.


omenie avatar

Utterly brilliant. And so relieved the little fella got home in 1 piece.

BlueSky avatar

Perhaps a .125W resistor would get up to temperature quicker than the 1/4 or 1/2W.

Dave Akerman avatar

A little, but probably not enough. I think the cord managed to move onto the wire (as shown in one of the pix) which doesn’t help. Anyway, using a smaller value resistor and more volts more than doubled the power for the second flight. Also the resistor was brought onboard so it would have started at around 0C not -50C.

AndrewS avatar
Patrick - Bethesda, Maryland, USA avatar

The Earth rotated during Babbage’s flight. Plus, there was wind present.

So, it seems to me that he could have landed many miles away. Potentially, he could have landed in the ocean or Iceland or Canada.

So, tell me please – how did he come to land so relatively near by?

liz avatar

General relativity (why don’t you zoom down the carriage if you jump up and down on a train?), and some attention paid to wind direction and speeds.

Patrick - Bethesda, Maryland, USA avatar

That was short, sweet and to the point.

I understand !!!!
Thanks Liz.

Peter Stevens avatar

Ooh you didn’t want to go there…

In an inertial reference frame you do indeed land on the spot you started. Unfortunately you’re in a rotating reference which isn’t inertial and even using Newtonian physics you can measure how fast you’re rotating by removing the entire atmosphere, firing straight up in the air and measuring how far away from you it lands.

To over simplify horribly, imaging a perfectly spherical earth of circumference 40km. On the surface of this earth at the equator you’re travelling at roughly 1.666km/s in a circle around the axis. At an altitude of 40km, you’re now a circumference of 40,251km. If you imaging sitting there for 24 hours you’ll travel the same 40km as the surface of the earth beneath you, but at this altitude you don’t get the whole way around – you’re 251km short. So if you don’t change your horizontal velocity during the ascent, from the point of view of the sensible people on the ground you’ll travel opposite to the earths spin at around 251km/day. Now for a 3h30 flight time that’d give you a drift of about 36km. However, you’re not at that height the whole time (roughly halves it), you’re not on the equator (roughly halves it again) so you’re actually expecting around 9km of drift due to the earth moving beneath you were it not for the fact that the atmosphere is terribly significant for helium balloons which have no mass and huge drag coefficient so all that calculation is completely and utterly irrelevant because they just follow the air currents.

Peter Stevens avatar

That’s a circumference of 40,000km obviously…

Dave Akerman avatar

“They just follow the air currents” – yep, that’s my stock answer :-)

liz avatar

I’m so glad one of us stopped playing Starcraft at university for long enough to pay some attention. ;)

Jim Manley avatar

What, no discussion of the fact that the mass of the planet and all of the teddy bears, balloons, Pi boards, people, Smarties, etc., stuck to it is decreased ever-so-slightly whenever Babbage and his balloon rig take off, causing the rotation of the Earth to incrementally speed up due to the decrease in rotational inertia as the mass of Babbage and his rig goes away? Oh, the humanity (or, bearanity in this case, I suppose), indeed! :D

At least I think it speeds up, but I may have it backwards. I’m trying to relate it to when an ice skater pulls in their arms and legs to speed up the rate of rotation as the moment arm is reduced, instead of the mass. Where’s a licensed physicist therapist when you really need one? :lol:

liz avatar

No idea. I’m too busy playing Starcraft. ;)

Steve avatar

When’s Picraft coming :)

Pygar avatar

Meanwhile, the Earth sweeps up untold tons of dust and ice every day, mostly far smaller than the bean-sized gravel that makes a visible “shooting star”… and it all settles to the ground eventually, pretty much. So our Borg Bear is waaaaaay down in the statistical noise of gravity, inertia, and such… I’m talking, “make a right at the decimal point and pack your lunch, it’s a long walk”.

Jim Manley avatar

Curmudgeon! Spoilsport! Next thing you’ll be telling us is that the Earth (along with the poor, defenseless teddy bears and kittens … kittens, mind you!) is spiraling inexorably toward a Sun that’s on its way to becoming an iron cinder in another five billion years, or so. Before that happens, you will say, that same Sun will first morph through a red giant phase that will expand to engulf all of the planets, moons, teddy bears, and kittens probably out to Mars. When will this slow, agonizing punishment end?

Besides, don’t you know how many decimal places to the right “ever-so-slightly” is? That packed lunch had better include a full-on Thanksgiving turkey dinner (or substitute your favo(u)rite holiday feast here) and the walk had better be in hiking boots … on an intercontinental flight! :D

Pygar avatar

Now, now, you can’t mention Thanksgiving dinner and expect me to *think*, all on the same day!

Whenever anyone mentions horrendous disasters, I try to get over to YouTube- they’ve got the last 3 or 4 minutes of “The Man Who Could Work Miracles” somewhere around there.

I am *not* a curmudgeon, but am studying hard and have every confidence in passing my finals, btw. I just didn’t want anyone to think the world was in any danger because LoCUTEus had left it for a while (well, 24 miles or so, anyway…

Steve Smith (G0TDJ) avatar

A great effort from Dave and the team. It was a lot of fun tracking, receiving telemetry and, in a small way, helping out with directions etc. across the internet.

Very much looking forward to the UKHAS Conference in September ( and future launches.

Mark Swope avatar

I really enjoyed following Monday’s flight. Was Dave able to verify at what altitude Babbage left his platform?

Dave Akerman avatar

Only that it was > 39,000 metres. The exact point was recorded by Babbage as his GPS dropped out when he switched to video mode at 38km, however we do know that the cutdown was triggered when the PIE GPS saw > 39km, and would have triggered after about 2 seconds (10 metres or so).

Dave Akerman avatar

Sorry, *wasn’t* recorded by Babbage.

Mark Swope avatar

Thanks for the reply, Dave. Now, for an even more important question: Is the bear’s name “Babbage,” or is it “Ted?” I’ve seen both.

liz avatar

It’s Babbage. For the purposes of this flight, though, there was a pun in play: Felix Baumgartner’s jump was called Red Bull Stratos, so this flight got called Ted Bull Stratos because Dave thought it was funny.

AndrewS avatar

Wasn’t “TED” the name of the tracker, embedded inside Babbage?

liz avatar

It was. For double confusion, we were also referring to Babbage as Ted occasionally.

Dave Akerman avatar

I was going to call Babbage “BABBAGE” on the map and the image page, but the image software is limited to 6-character names, and “BABBAGE” is too long. So I opted for “TED” for both, to be consistent.

The Raspberry Pi Guy avatar

Excellent… Just plain brilliance there! If that doesn’t get people interested in electronics then I don’t know what will! I would of loved to have been at the launch site!

The Raspberry Pi Guy

Norman Dunbar avatar

I must congratulate Dave on his excellent taste in music. I can see the album cover from Jim Steinman’s “Bad for Good” album in the stills above!

I once had an artist friend of mine paint me a copy of that particular cover – that was back in the eighties! I still have it, somewhere!

Oh, well done on another record too!


Dave Akerman avatar

Well spotted, and heah, I’m a big fan, met him a few times etc.

Chris Bradfield avatar

Pleased to hear that on the second flight, Babbage leapt as intended, aided by the resistor melting the nylon tie. It reminded me of two past experiences. One was in Cambridge, when our lab technician had a delightful kit for welding up small thermocouples – a bench power supply to charge up a stack of electrolytic capacitors, probably a couple of thousand microfarad each, charged to say 30V. A trigger circuit used a thyristor to discharge this bank into the fine wires to be welded, probably sandwiched between an electrode on the positive side of the supply, and a baseplate on the negataive side. Secondly, some years later, I wanted to release a restraint on a mechanical system, and to know the instant of release, before recording the subsequent vibrations. I proposed using a piece of fuse wire at the restraint, and melting it using a similar arrangement to discharge energy into the fusewire. – monitoring voltage and current across the fusewire would allow us to identify the moment when it melted. I offered this as a student project, but unfortunately have no definitve results, as the student decided that the idea was impractical, and devoted most of the project time to proving that!! But is there any merit in replacing your resistor by a short length of fuse-wire, with the nylon cord looped over it. Probably one needs to look at both your scheme and this, to see which ekes out the energy budget better. Thanks for an interesting weekend, and well done.

AndrewS avatar

When I was at high school we were plotting volatge/current graphs of some component – I think it was a diode but might have been a resistor. We cranked up the voltage to higher levels than we were supposed to, and all of a sudden the current level dropped to zero! The component had got so hot that it had unsoldered itself and fallen off the bottom of the mounting frame ;-)

Steve Williams avatar

Love the video of the start of Babbage’s jump. Did the chute open properly? Hope to see some descent videos too.

liz avatar

There’s not a lot of atmosphere up there, so the chute doesn’t open until it gets lower down, where there’s enough air to fill it.

Dave Akerman avatar

Yes the chute opened correctly, and worked very well so he had a nice soft landing.

Which is just as well with that wire stuck in his bum …

AndrewS avatar


Mac Rutan avatar

This is my favorite project yet! I’m looking forward to interviews with Babbage!

Winfried Ursin avatar

Now on Austrian TV
Greetings from Salzburg, where Felix Baumgartner and Red Bull have their home.

All the best

JBeale avatar

More thoughts on ruggedizing, in addition to gluing (or soldering?) the SD card into place. When you separate Vehicle A from Vehicle B in the stratosphere, is there a possibility of a static charge buildup as the nylon cords, parachute etc. drags past the host vehicle? ESD could be a factor?

Alex Eames (RasPi.TV) avatar

You can’t change thumbnails on YouTube vids unless you become a “Youtube channel partner”. Unless you do that it selects them for you automatically from the worst shot it can find. ;)

Alex Eames (RasPi.TV) avatar

Correction – it gives you a choice of the three worst shots it can find. ;) I wonder what the other two were like ;)

Dave Akerman avatar

I don’t remember changing anything or being asked! Anyway, I’ve chosen a better shot now :-).

liz avatar

I just have a very expressive face. Right now it’s doing this. :(

Alex Eames (RasPi.TV) avatar

Oops. Sorry Liz, I didn’t mean to be rude :( I was trying to be helpful and humourous.

I hope your expression changes massively for the better on hearing good news later today. If Pi wins tonight I hope you’ll be :) for a long time.

liz avatar

Not at all – I may look grumpy, but within I am full of joy and gladness (no results here for a couple of days, but we *do* get a lot of herring).

Matthias avatar

Awesome! It made it up to Austrian online news broadcast!

Congrats from me this is really really a cool project!

And Felix B. got red cheeks like a little girl when he see how brave Babbage jumps in to the depth! :)

Greetings Matthias

Dave Akerman avatar

I’ve had more media requests from Austria than anywhere else. I wonder why …. :p. One today was from a station owned by Red Bull :-)

Winfried Ursin avatar

Talk to the Red Bull TV Station, they are very Close to the owner of Red Bull who might as well Support the Raspberry Pi Idea, as he also supports a lot of other youth initiatives!

Fabrizio avatar

I’m trying to explain my cat that he can’t do the same jump. He saw the video and strangely understood that Babbage was quickly falling, and wanted to follow him :)

Jim Manley avatar

There is a certain dog from “The Far Side” comic strip saying, “Please, please, please, oh, PLEEEEASE!!!” :D

Fabrizio avatar

And, most importantly, was is complicated to obtain all necessary permissions to launch, I mean airspace closures, air traffic control stuff, defence etc…?

Jim Manley avatar

If the balloon and payload are small and light enough and remain below a threshold for battery power, they can be launched in many places with little/no notice. However, launching sites have to be far away from any controlled airspace, airways (typically between airports and/or navigation beacons), and anywhere else aircraft may typically be found. Obviously, for example, the approach and departure ends of Heathrow’s runways might be extremely seriously frowned upon (can you spell anti-terror laws?) at any time of day or night – Dave’s back yard, not so much :D

As balloon and payload sizes and weights increase, so do the restrictions and requirements for adding things like strobe and navigation lights, radar corner-reflectors, fluorescent/glass-granular-reflective paint, etc. NOTAMS (NOtices To AirMen) are required some number of days in advance of a date/time of intended launch, again with size/weight being proportional to the advance notice period required.

Civil aviation authorities obviously need to be notified of an intent to launch and they will know of potentially conflicting activity and can coordinate a location/date/time most advantageous to the launcher, while being as safe as possible for everyone else. Predicted weather right up to the launch window can also determine a go/no-go, especially if the winds aloft at aircraft altitudes are strong enough to potentially take the craft into controlled airspace or an airway during the expected ascent and descent period.

I hope we don’t start seeing a “rain of ted-bear” meteorological phenomenon as a result of all of this Ted Bull fun ;)

Hans Wenzl avatar

What a brave little bear! Hope to see him shake Mr. Ban Ki Moon’s hand quite soon.

AdrianBevan avatar

Heartiest congratulations to you Dave, and the team. I bet Paddington never had such adventures and must be green with envy !!

Ratti Von Plush avatar

Well Done to Babbage. I am sure he was really cold up there and you made him go up twice! Shame, that is seems like a bit unfair on him. Pleased that he made it back, not so happy that you took out his FLUFF. Open-Fluff surgery need to be undertaken under by a qualified Doctor of Plushi and Fluff Medicine. Pleased a PLushi holds the record and not a HUMAN.

Ratti von Plush
Grand Vizier of PLushiland
Office of the King
Plushi Towers

John Holroyd avatar

I find this whole project disappointing. The images of the bacon are out of focus and that pretty much ruined it for me. Then, to compound the issue, the bear had no space suit. Now that is mean and is just a shame as everything else is truly spectacular. Some detail on how the telemetry was accomplished would be appreciated.

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