Twenty passengers on missing flight 370 worked for Freescale Semiconductors

[EEVblog]

- 60 feet is generally considered to be the upper ocean layer so 30m / 100 feet seems more reasonable.

I recall there was a mechanical depth stop so you could select between two depths. This was almost 20 years ago though, so my memory is a little fuzzy. I started work on them in 1995.

[EEVblog]

I guess the sink is a measure to avoid any encounter with ships and marine life (sharks etc).

The float bag would eventually degrade and leak anyway, and the whole thing would sink.
But the scuttling was built into the spec as a "security measure".

[EEVblog]

When I was in the army in the 1980's the dragons (anti tank missiles) were already costing $10k a piece and for practice those guys shot around 5 pieces a person (6 persons) in a weekend, and that was just the yearly training. Add tankshells, mortars hell laserguidedmissiles and $5k is peanuts.

IIRC the production contract of 15,000 units was based on a 5 year supply for the navy. Do the math 

[Kjelt]

IIRC the production contract of 15,000 units was based on a 5 year supply for the navy. Do the math 

15k*5k = 75M$ that is a bit more then the price of a Boeing AH-64D Apache helicopter, I mean in the defense industry the numbers are huge 

[KJDS]

IIRC the production contract of 15,000 units was based on a 5 year supply for the navy. Do the math 

15k*5k = 75M$ that is a bit more then the price of a Boeing AH-64D Apache helicopter, I mean in the defense industry the numbers are huge 

Now do the numbers for mobile phones, televisions and PCs.

[Kjelt]

Now do the numbers for mobile phones, televisions and PCs.

[CaptnYellowShirt]

IIRC the production contract of 15,000 units was based on a 5 year supply for the navy. Do the math 

15k*5k = 75M$ that is a bit more then the price of a Boeing AH-64D Apache helicopter, I mean in the defense industry the numbers are huge 

I used to know a crew chief for an Apache. He said the Apache has a set of frangible main rotor tips that run $100,000. They're designed as a safety measure for low-level maneuvering. If the pilot gets too close to a tree, these tips hit first, shatter, and protect the main rotor and blades.

This crew chief said that during each training mission, there would be at least one Apache that came back without  its tips. And this is perfectly OK.

The view isn't: $100,000 is a lot of money. Its: $100,000 to save a $15M aircraft is a good bargain.

[dr.diesel]

Its: $100,000 to save a $15M aircraft

And more importantly, the lives of the men/women inside!   

[CaptnYellowShirt]

Its: $100,000 to save a $15M aircraft

And more importantly, the lives of the men/women inside!   

True, but there's a reason only the pilot gets the airbag. It doesn't have anything to do with the crash-worthiness of the front seat.

[Kjelt]

The view isn't: $100,000 is a lot of money. Its: $100,000 to save a $15M aircraft is a good bargain.

Make that an $52M to $61M aircraft 

http://www.aircraftcompare.com/helicopter-airplane/Boeing-AH-64D-Apache-Longbow/263

[pickle9000]

Most of this info is from the CBC website in Canada.

- The sona-buoys do have a 300 meter operational depth. The Australians are described as "world leaders in the field"
- 4500 meters is the approx depth of the signals. There is a deep trench (Diamantina) near the signals 5800 meters and there is no indication it is in the trench.
- Expected battery life for the pingers is less than 10 days, described failure mode is decreasing signal strength until it stops. This was from an internal briefing (for the members of the search team) that was leaked.
- The Bluefin robot with the sidescan sonar will not be launched until pinger contact is definitely lost. I guess that means 10 days or more. The dive will be a the maximum operational depth for the robot.
- There are a number of other deeper diving subs that can be used if needed. That would delay things while they are transported.
- Still no mention of an actual ROV to visit the site. The Woods Hole Oceanographic Institution is mentioned and they have a vast array of ROV's so that would be my guess.
- The British sub has been doing a search around the initial Chinese ping contact and there has been no reports on any more signals found in that location. There has also been no reports of it moving to another search location.

[tom66]

This is magic - almost like a Mars rover landing - perhaps not quite as advanced but still impressive!


(not the same as used for the aircraft search - not sure what this is for...)

[EEVblog]

This is magic - almost like a Mars rover landing - perhaps not quite as advanced but still impressive!

Yes, trust me, it's not easy to get that stuff right.
I'm not sure what one that is, but our Barra 6PC Sonobouy deploys almost identically. It has the same extending 5 arm design with 5 hydrophones each.
We spent years perfecting the design of the "gravity jerk" technique of the arms self extending and unfolding, not to mention the coiling of the wires so they didn't get tangled etc.
I remember drop testing those, you can buckle half inch steel plates if it hits the water at the wrong angle, it can be like hitting concrete.

[kizzap]

For this purpose it seems a little silly that they wouldn't modify the sonarbouys to not sink, so that someone can come pick them up later. I get that you don't want this tech public knowledge, but it just seems silly.

[EEVblog]

For this purpose it seems a little silly that they wouldn't modify the sonarbouys to not sink, so that someone can come pick them up later.

They are not designed to be reusable, so it's pointless picking them back up. Also, it costs more money to retrieve them than it does to let them sink.

[pickle9000]

These are the guys that are responsible for the black box finder and own the side scan robot. The web site is interesting and they are fully equipped to handle the recovery. They did the Air France recovery, at least 50 recovery's for the military, Space Shuttle Columbia and so on. It would make an interesting documentary. 

http://www.phnx-international.com/uw-search.html

[SeanB]

The view isn't: $100,000 is a lot of money. Its: $100,000 to save a $15M aircraft is a good bargain.

Make that an $52M to $61M aircraft 

http://www.aircraftcompare.com/helicopter-airplane/Boeing-AH-64D-Apache-Longbow/263

just do not ask how the pilot ejection system works, it removes the main rotor blades by firing a jam block into the main gearbox ring gear and this then fractures the rotor hub allowing the blades to fly free, the pilot and copilot then going up through the place just vacated. Biggest difficulty was making the fuses armoured well enough so they would not fire if the engine bay was on fire, or to fire if hit by small arms fire or even larger fire that did not disable the gearbox instantly.

If you think the purchase price is high, look at the cost of running any military aircraft, and as they typically operate for decades your spares cost makes the purchase price seem like just a minor cost. It may well cost more for a regular major airframe overhaul than the original purchase price. The regular sceduled services and line service as well is not cheap, and the funny thing is an aircraft running cost is more or less constant, more flying is not a linear rise in cost, as things still fail or time expire even if not in use. There is an incredible amount of rubber and synthetic rubber in hoses tanks and wiring looms in the airframe, all of which has a service life in both hours, cycles and time that need regular scheduled replacement with new.

[pickle9000]

Time for the robot to get wet. It may already be in the water. The sonar data is on board I'm not sure if they have any real time info. The Navy has several of these but it appears that at least two are on site. No mention of the search pattern but that would be interesting. Expected coverage is 40 square miles per day.


Here are the details from the US Navy (Naval Sea Systems Command) http://www.navsea.navy.mil/SitePages/TPL25_bluefin21_faq.aspx

Bluefin-21

Q. What is the Bluefin-21?

Bluefin-21 is an autonomous underwater vehicle (AUV) that can be equipped with either a side-scan sonar or a still camera to gather underwater data.  Bluefin-21 is 16.2 feet long, has a diameter of 21 inches and its dry weight is 1,650 lbs. Its depth rating is 14,763 feet and has a maximum speed of 4.5 knots. Its mission endurance is 25 hours with standard payload at a speed of 3 knots.   

Q. How does this system work?

Technicians program the Bluefin AUV to search a specific area before the vehicle goes in the water.  During the search, the system uses a side-scan sonar or a still camera to gather data. Once an area search mission is completed, the AUV is removed from the water and plugged into a processing suite for data download. The data is then analyzed. While data is being analyzed, a subsequent mission may be programmed and the AUV may be deployed to perform its next area search.

Q. How much ocean can be covered by the Bluefin-21?

The effective range of a sonar device and therefore the Bluefin-21 is dependent upon a number of factors. These factors include the water depth within the search area, the contours of the sea floor, and the size of the material being searched for.  Therefore it is not possible to provide a standard maximum range for the side-scan sonar/Bluefin-21. However, as a rough estimate, the Navy expects to be able to search approximately 40 square miles per day using the Bluefin.  This estimate will be affected by the specific environmental factors encountered.

[EEVblog]

If they have fairly well pinpointed the location enough to send down the sub, I'm surprised they haven't found any debris yet. Debris is always the first thing found in these ocean crashes.
It would be hilarious if they found the black boxes, but not a single piece of wreckage.

[pickle9000]

If they have fairly well pinpointed the location enough to send down the sub, I'm surprised they haven't found any debris yet. Debris is always the first thing found in these ocean crashes.
It would be hilarious if they found the black boxes, but not a single piece of wreckage.

My nephew said that 2 hours ago! 

I suppose it's possible that the fuselage could be in one piece but that's hard to imagine. Luckily when it comes to things like this the evidence will be waiting there you just have to go get it.

[Wytnucls]

Don't hold your breath, finding anything could take a couple of years or more, if someone still pays the bills. But it seems that luck has been on their side so far, so let's see.

[pickle9000]

I wonder how much input the Phoenix International crew have on the search? They certainly have the hands on experience.   

[Kjelt]

What if................
they flew so low (under radar) and made a belly landing on the sea, so no crash just plain landing on the sea, would there still be debris or would it just sink to the ocean floor?

[Nermash]

I wonder why they didn't sent in HMS Echo to do a sonar sweep first, to get at least a broad picture of what is down there, then send the sub.

[amyk]

It would be hilarious if they found the black boxes, but not a single piece of wreckage.

That would be a real WTF... implying that somehow, they were able to remove them from the plane and throw them out into the ocean while still flying?