votingprawn

> I haven't checked the exact circumstances of the 'drone' being near a aeroplane, but if it was more than 50m away from the 'vehicle' at all times, it would appear that what happened was not forbidden.

Even if they hadn't been operating beyond the Visual Line of Sight (VLOS) conditions (they were apparently at 700ft, CAA accepts VLOS to be below 400ft), I wouldn't be surprised if the aircraft was in breach of other rules, such as operating an FPV/Surveillance aircraft over a congested area, or within an aerodrome traffic zone.

> The rule requiring line of sight is interesting, as it forbids what seems a likely common use - looking where you can't see.

I think you'd be surprised at how much of a "non-issue" this is (excuse the awkward grammar). UAVs are my profession and I do a lot of surveillance and data acquisition work, and I can't remember ever _needing_ to fly out of VLOS. Real time video feeds give you a great view of what is going on in front of the camera, but not of what is happening around the aircraft. As advanced as UAVs have become they are not infallible and, as unlikely as it may seem, you should be prepared for your flying blender to fall out of the sky at any moment.

We were operating just a few days ago and the crew list was: pilot, pilot's spotter/assistant, payload operator, and three spotters. This may seem like overkill but a 7kg object falling from 50m can do some serious damage, and that is assuming the blades stop spinning on the way down.

Small Unmanned Aircraft (SUA) flown under FPV are defined under a separate exemption from Small Unmanned Surveillance Aircraft (SUSA), although the rules broadly overlap. Additionally for FPV the CAA mandate you must have a competent observer who can maintain unaided visual line of sight with the aircraft at all times.

I suspect their 150m surveillance rule is part privacy, and part a belief that if you're trying to film something/somebody with a camera you pose a higher risk than if you're just flying past them.

Top quality reporting. "Senior engineer with 20% more experience receives 20% higher salary"

Ah sorry I was unclear - I was referring to an actual thread on HN: https://news.ycombinator.com/item?id=8526805

> It's really unfortunate though there there are people who can't resist the urge to shame others and enlighten the world with their sharp & intelligent wit

Amusingly this has now happened in another thread in these comments.

The meaning of a post has been overshadowed by a conversation on how the author used word A when they really should have used word B, and then they were berated for trying to explain why they thought word A was acceptable in the context.

From the image in the article it looks to me like the researchers are using commercial software from Agisoft, called PhotoScan[0].

For free (but not enitrely OS) you can look at VisualSfM[1], which is a GUI which pulls together a variety of separate tools to generate SfM. You can run all these tools seperately too, VisualSfM just vastly simplifies things. The author (Changchang Wu, now at Google) has a couple of interesting papers on the algorithims[2].

Both the commercial and the free software largely give you the same quality of result, the commercial stuff is just usually much much easier to work with.

As always, quality of your source imagery is paramount. I can't over emphasise how much geo-referenced images will help you. Second best is some "ground control points" (ideally with GPS locations). I've had limited success with completely unreferenced datasets but it is a slow process.

My workflow with GoPro video is to first defisheye the footage in CineForm Studio (there are other ways, but I find their defisheyeing to be pretty good), then I grab a frame every second or so from the footage depending on how fast I was flying around the object of interest. Too much data can almost be as bad as too little data!

[0] http://www.agisoft.ru/ [1] http://ccwu.me/vsfm/ [2] http://ccwu.me/vsfm/vsfm.pdf

Probably worth pointing out that the FLIR FX is just a HD webcam, not a Thermal Infrared camera.

Flir sell uncooled TIR cores (Tau and Quark) which will very happily sit on a small multirotor or fixed wing.

"Sense and avoid" is the current holy grail of UAV research.

Restricted zones have some interesting effects. DJI, a Chinese multirotor manufacturer, recently introduced 'no-fly zones' around airports for their ultra-consumer-level uav, the phantom 2. An unfortunate side effect, in the UK at least, is you are now unable to fly your phantom 2 in areas where it is perfectly legal to do so. I believe this limitation also effects where you can place waypoints on their more advanced autopilots.

They also prevent you flying over or near Tienanmen square...

Can you share any more on this project?

We're currently working on a project for an environment agency to determine viability / produce a proof of concept for monitoring methane levels over landfills using UAVs.

> As an ad for the pizza company, it works well though given how much this video seems to have been shared.

I was exhibiting at a UAV conference back in November, at there was a guy from Hootsuite exhibiting for the conference next door.

He spent quite some time trying to convince me that we should be working with pizza companies on an advertising campaign involving UAV delivered pizza. He was right, it's a good 'viral' ad idea.

> it didn't seem automated in any real sense.

From the GPS/Compass mount and the flashing LED I think its a pretty safe bet that it's a NAZA flight controller, which doesn't offer any autonomy (beyond stabilisation and GPS assisted position hold). So someone is flying it by remote control, like any RC aircraft.

They're Aluminium over a steel core, not copper. A copper over steel version would be significantly heavier.

> I wonder why this didn't take off.

I think mainly because there isn't much of a usecase for most people.

We use Structure from Motion techniques a lot here where I work (Research Institute) to construct 3D models of buildings and land from UAV imagery.

The current methodologies are great for this use, but they lack the accuracy you'd want to model an object on your desk for 3D printing. That's not to say you can't do it - there's just often a lot of work to be done on the mesh afterwards to make it work.

Autodesk make a pretty good app called 123D catch [0], which uploads your images to their servers for processing.

Alternatively VisualSFM[1] is what I mostly use, I get great results but I don't know how good it is with small things.

[0] http://www.123dapp.com/catch [1] http://ccwu.me/vsfm/

> The prop tips are well into the supersonic range.

I've yet to come across any firm proof that the Bear has supersonic tip speeds, even the wiki article says "according to one media source".

Now obviously with any prop aircraft you can generate a scenario where the tips go supersonic, but I feel "The prop tips are well into the supersonic range" is a disingenuous statement. I do agree with you in general principle though - tips can, and do, go supersonic.

Some back-of-the-napkin calculations for the Bear, using the figures given by the media source on wikipedia: 5.7m prop diameter 750rpm at cruise

Circumference = pi*diameter = 18m 750rpm = 12.5 rotations a second

Giving a tip speed of 220m/s, so contrary to the media source the blades are not supersonic by themselves.

You could, of course, engineer a scenario where the combination of the airflow through the prop + the prop tip speed > mach. But you can do that with a Boeing Stearman too, you just avoid it by design due to the increase in drag, and not to mention the stress placed on prop blade that is subsonic at the root, transonic in the middle, and supersonic at the tip.

I've seen people give the noise created by the Bear as evidence of supersonic blades, but I'd put that down to interactions between the contra-rotating props, a bit like blade slap on a helo.

Now the Republic Thunderstreak is an interesting story - a plane with (proven) supersonic blades: http://www.youtube.com/watch?v=UFhSzReWTgs

> I should also remind you that a year ago NASA didn't actually know "how" the j-2 worked. Their numbers said the bell should melt during flight. Eventually they realized that helium is injected on a outer ring of injectors to insulate the bell.

I think this is remarkable, given that film cooling of the nozzle is a known aspect [0] of the first stage engines of Saturn V.

[0] Thrust Chamber Nozzle Extension section on page 3 http://history.msfc.nasa.gov/saturn_apollo/documents/F-1_Eng...

I've never understood why USA PhD students appear to be paid so badly. My stipend was 36k USD (tax free, so compared favourably with the salaries of my friends who went into industry). I worked pretty much 9-5 with the occasional late nights, and got paid an additional $23/hr for work not related to my PhD (teaching, work on other research projects).

Interestingly if I'd gone into industry I'd have been earning much less than my equivalent in the USA.

> allows rich people in power to remotely kill people they deem as threats whilst selling a story of reduced casualties on both sides.

Don't expensive manned aircraft with (the same) expensive precision guided munitions allow rich people to do exactly the same thing?

A manned aircraft could perform these missions with the same level of "collateral damage" and minimal risk to the pilot.

Couldn't the same argument be made against any other attack aircraft?

I'm surprised, I would have thought that hitting 3/4 of a ton of cow 55mph would do significantly more damage than we can see here.

I'm also struggling to find any reference to this 3 year struggle prior to two weeks ago. Sounds like a nice little Halloween hoax, the "Editor's Pick" comment stating how its definitely not a hoax only makes me more inclined to believe it is.

In fact, after a quick browse it seems to me the Editor is only "picking" comments that support the concept, not those that offer plausible explanations or interesting discussion.

Hmm yes perhaps, I tend to think of a dial as part of a measurement device. So a volt/ammeter has a dial, a clock has a dial etc.

I suppose I could see myself calling the temperature setting of a cooker the "Temperature dial", but not the mode selector knob thing. Mode/Temperature selector is quite a good one actually. Still doesn't come to hand like knob does though.

Plenty of British English speakers would use the word "knob", for example I have no idea what I would call the knobs on the cooker other than knobs.

Or the knobs on amplifiers, or door knobs - well I suppose door handle works but door knobs are distinctly different from handles in my mind.

I had assumed that they were emphasising "non-military" to avoid association with the bad press armed "drones" have been getting.