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Comment: Re:Mystery (Score 1) 442

by oobayly (#49377869) Attached to: Why the Final Moments Inside a Cockpit Are Heard But Not Seen

Um, ignore that last comment, I completely misread what you said - facepalm.

However, I based the cost on using satellite 100% of the time, and I've realised that actual cost could be 50% (2c per second), and is likely to come down in the future. If you're needing to send 6kB/s per aircraft HF obviously is not the way to go, but it doesn't mean that the bandwidth isn't available.

Comment: Re:Mystery (Score 1) 442

by oobayly (#49377861) Attached to: Why the Final Moments Inside a Cockpit Are Heard But Not Seen

I didn't think of that in this case, however I've come across this in the past. Internet on Irish Ferries is (was? - it's been a year) via satellite (the provider is in Norway when I did a whois on the public IP) even when within range of land or when docked. I couldn't understand why their AP didn't route depending on whether it was within range of a 3g cell.

Comment: Re:Mystery (Score 1) 442

by oobayly (#49377803) Attached to: Why the Final Moments Inside a Cockpit Are Heard But Not Seen

Rolls Royce already do this with their engines - if you have the right contract your ground crew will be alerted that there - for example - are too many metallic particles in a gearbox, without the pilots ever knowing. I think it's done because RR have maintenance contracts and catching issues early saves money (and looks good). I'm sure GE and others do the same.

There's probably a myriad of reasons. Building a standard takes some time - manufacturers will probably have their own propriety methods and will want theirs to be the standard as it will cost them less. Systems will have to be certified. Airlines will have to pay for this equipment, plus the time and money to train technicians.

I can see this happening sooner than expected after the disappearance of MH370 and this crash. We're now getting to (or already have arrived at) the stage that the aircraft an becoming more reliable than the aircrew. Don't get me wrong, BA Flight 36 and US-1549 have show that pilots are better than any computer at dealing with unexpected situation.

Comment: Re:Mystery (Score 1) 442

by oobayly (#49365501) Attached to: Why the Final Moments Inside a Cockpit Are Heard But Not Seen

Only one thing I disagree with - bandwidth costs. The FDR [apparently] records at about 6kB/s (I'm trying to find a source to back that up), so that's 6kB/s per aircraft in satellite data costs. There can be up to 11,000 aircraft flying at any one time, so that totals 66MB/s of bandwidth required globally. I don't believe lack of bandwidth is a factor.

Bandwidth is apparently between 5 and 7 USD per MB, so about 4c per second. In comparison, and A320 consumes about 665 gallons of fuel per hour, equating to about 29c per second. It's not an insignificant increase in cost. Along with that, the cost of equipment, certification, etc is why we haven't seen it yet, though I believe there are working groups.

There is also the issue that it will always be possible for the flight crew to pull the breaker on the transmitter, much like they can pull the breaker on the CVR (and probably the FDR), so that doesn't solve the issue when it comes to a malicious agent.

Comment: Re:Still waiting for a "hackability meter" (Score 1) 159

by oobayly (#49349905) Attached to: Many Password Strength Meters Are Downright Weak, Researchers Say

Why should there be a character limit on passwords? Providing you're hashing them then storing them just needs a constant width field. If you're dealing with html inputs, then the default is not to have a maxlength attribute and if you're POSTing the form data then you're unlikely to hit any limits.

Comment: Re:This validates the US policy... (Score 1) 737

by oobayly (#49346397) Attached to: Germanwings Plane Crash Was No Accident

I imagine we'll being seeing this policy across EU airlines pretty damn quickly. I also guarantee that all flight crew members will be looking at where the door mechanism is on the flight deck and how to use it. As you say, it would take very little time to open the door - we're talking about real life here, it's unlikely that a single man will be able to knock out anyone in an instant, especially while sitting down.

Comment: Re:Photosynthesis thumbs up! (Score 1) 65

by oobayly (#49217161) Attached to: Solar Impulse Plane Begins Epic Global Flight

There are some difficulties when it comes to scaling aircraft. Very simply:
Lift = Air_density * Velocity^2 * Coeff_lift * Wing_Area / 2
Drag = Air_density * Velocity^2 * Coeff_drag * Wing_Area / 2
Coeff_drag = Parasite_drag + (Coeff_lift^2 / (PI * wing_span_efficiency * wing_aspect_ratio))
efficiency is a number in the order of 0.85 to 0.9

So, whilst you only have to increase wing area linearly with mass (or increase speed to the square root of mass), doubling your speed quadruples your drag, and doubling your lift quadruples your lift-induced drag.

I can't do the numbers at the moment, but it should be quite easy to determine scale at which an electrically powered aircraft is not longer possible (using current technology)

... though his invention worked superbly -- his theory was a crock of sewage from beginning to end. -- Vernor Vinge, "The Peace War"

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