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Comment: Re:Sort-of-worked. (Score 1) 54

by photonic (#49630511) Attached to: SpaceX Launch Abort Test Successful
They want to re-use this Dragon for an in-flight-abort test, using a Falcon 9 first stage launched from Vandenberg, so purposely introducing mechanical flaws seems risky. If it were a deliberate test, I would be simplest to just set the throttle to one of the motors to zero in software close to the end of the burn (to not ruin the overall test in case of problems), and then see if the control system can recover using the remaining 7 engines. Let's hope that Elon comments on this in the next days ...

Comment: Re:Sort-of-worked. (Score 5, Insightful) 54

by photonic (#49630027) Attached to: SpaceX Launch Abort Test Successful
No, OP's remark was correct, he is not discussing the planned pitch over towards the sea after half a second, but a visible puff of smoke around the 4 second mark and some subsequent 'wobble', as if one of the 8 thrusters is switched of. See the zoomed video here. This proves the effectiveness of having 8 redundant thrusters, instead of having only 4. It is still not clear if this was a real engine failure (which might be verified via post-mortem examination of the motor), or if this was a deliberate, unannounced test of the 'engine out' capability. Credit: the discussion in the forum over at nasaspaceflight.com.

Comment: Re:Graceful degradation (Score 1) 250

by photonic (#49600045) Attached to: Long Uptime Makes Boeing 787 Lose Electrical Power
Indeed, they would need some mechanism like this, which is implemented using several heterogeneous processes. Triple hardware redundancy is useless if they all have a common mode software bug. Same thing happened to the first flight of Ariane 5, where all 3 controllers crashed within milliseconds.

Comment: Bigger issues (Score 1) 1089

by photonic (#49295843) Attached to: Obama: Maybe It's Time For Mandatory Voting In US
I am neutral to mandatory voting. I believe they have this in Belgium, but it is not strictly enforced with sanctians, so the polical system works similar to neighboring countries. America has bigger political issues: 1) too large influence on politics of big money: by rich people via superPacs and by corporations via lobbying or outricht corruption. 2) Effective two party system, where everything is decided on a single left-right axis, so that non-issues like gun rights and being patriotic or christian enough decide all national politics. Fix these two issues first., then we can discuss mandatory voting.

Comment: Wolfram Alpha (Score 1) 210

by photonic (#49074953) Attached to: Interviews: Ask Stephen Wolfram a Question
I am not sure if we will get some personal answers out of this guy, I guess he will just forware every single question into one of these websites that claim to know everything. Serioudly, though, what do you think of Elon Musk's fear of A.I., and when do you think that Wolfram Alpha will become self aware?

Comment: Re:The Secret of Nim (Score 2) 520

by photonic (#49061029) Attached to: Nim Programming Language Gaining Traction
I completely disagree. I have worked extensively both with Matlab and Numpy, and I much prefer Python's 0-based indexing and half-open intervals over Matlab's 1-based indexing and closed intervals. Edsger Dijkstra, the famous computer scientist, explained why this is a good idea. E.g. splitting the first n items off an array in Matlab is head = x(1:n); tail = x(n+1:end) , while in Python it is head = x[:n]; tail = x[n:] . Even worse is when doing some computation over blocks within an array, in Matlab you do for i=1:n; y(i) = fun(x((i-1)*m+1:i*m)); end , while in Python it is for i in range(n): y[i] = fun(x[i*m:i*m+m]) . In Matlab, you always have to think careful about the extra +-1, which causes many off-by-one errors, while in Python you just write it down intuitively.

Comment: Re:Twitter: Ran out of Hydralic fluid (Score 1) 213

by photonic (#48782005) Attached to: SpaceX Rocket Launch Succeeds, But Landing Test Doesn't
The fact that he can make this claim only half a day after the fact (so I assume they had no time to piece together the debris) means that they did recover the most valuable part: the telemetry. Overall, they achieved probably 95% of the required challenges. With around 5 successful retro burns, 1 low-level flame out due to loss of roll control, 2 soft water landings, 1 bullseye impact on a boat and around ten successful low altitude tests with grasshopper, only extremely bad luck can stop them from making a good landing in the next few attempts.

Comment: Make fun of them as much as possible (Score 2) 182

by photonic (#48625071) Attached to: US Links North Korea To Sony Hacking
Some years ago, an advertisement for a Dutch insurance company made fun of some Stalinist dictator, without mentioning North Korea by name. As far as I know, this did not cause any large-scale hacking warfare against the involved company, but Korean diplomats were not amused. Watch it here while you still can. This regime cannot be ridiculed enough, Sony should just release the whole movie for free.

Comment: Too expensive (Score 3, Interesting) 36

by photonic (#48592523) Attached to: OpenMotics Offers Open Source (and Open Hardware) Home Automation
With 50 euro for a power supply, 100 for a sensor conditioning module (without the sensors!), 300 for a base station and 800 for a complete starter pack, I don't care if it is open source or not, it is way out of budget for the casual hobbyist. There are already enough different alternatives, most of which appear to be vapourware. Home automation seems easy enough that many people who follow the IoT hype start their own project. But we don't need more standards, we need less. The best would be if one of the existing protocols (not necessary that one) would win, so that people could mix and match their own components, which don't have to be more fancy than some arduinos and RPis thrown together.

Comment: Advantage of x-wings over normal fins? (Score 1) 96

Can some aerospace engineer enlighten me about the advantage of these tennis-racket shaped x-wings over some standard steerable fins which you see e.g. on a guided missile? I could imagine that the grid-shaped 'louvers' could be seen as many small fins in parallel, but intuitively I would think that one big fin would have more effect. Is it something related to hyper-sonic aerodynamics? Or is it mechanically stronger?

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