backtop


Print 63 comment(s) - last by Arc177.. on Feb 5 at 11:04 AM


Elon Musk  (Source: wired.com)
He offered his help to Boeing, but the company declined

Boeing's 787 Dreamliner jet has had a lot of troubles lately -- namely with its batteries -- and the last person the aerospace company likely wanted advice from was competitor Elon Musk.

Musk, the CEO of automaker Tesla and private space transport company SpaceX, recently told Flightglobal that the 787 Dreamliner's batteries are "inherently unsafe." His company SpaceX competes with the Boeing/Lockheed Martin partnership, United Launch Alliance, in the aerospace sector.

"Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," said Musk.
"Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature. Moreover, when thermal runaway occurs with a big cell, a proportionately larger amount of energy is released and it is very difficult to prevent that energy from then heating up the neighboring cells and causing a domino effect that results in the entire pack catching fire."

However, Mike Sinnett, Boeing's 787 chief project engineer, defended the design and development of the batteries.

"I design a cell to not fail and then assume it will and then ask the next 'what-if' questions," said Sinnett. "And then I design the batteries that if there is a failure of one cell it won't propagate to another. And then I assume that I am wrong and that it will propagate to another and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that."

Musk's Tesla uses batteries fueled by lithium cobalt oxide, which is what Boeing uses for the 787. Musk understands that these batteries have highly flammable tendencies, and even offered his help to Boeing in its construction, but Boeing declined.

"They [Boeing] believe they have this under control, although I think there is a fundamental safety issue with the architecture of a pack with large cells," said Musk. "It is much harder to maintain an even temperature in a large cell, as the distance from the center of the cell to the edge is much greater, which increases the risk of thermal runaway."

In a recent report by The New York Times, it was discovered that Boeing knew about the battery fire issues in the 787 before this month's problems occurred, which grounded the jets in the U.S., Japan and India.

The report said that Japanese airline All Nippon Airways (ANA) replaced 10 787 batteries from May to December of 2012. Reasons included an unexpectedly low charge in the main battery, batteries that failed to start normally and one battery showing an error reading.

Japan Airline (JAL) also had "several cases" where it had to replace the 787's batteries before the issues that occurred this month, but it didn't disclose an exact number.

The airlines said they reported the incidents' to Boeing, but Boeing felt they didn't need to alert safety regulators because it was not considered a safety issue, but rather "within the scope of regular maintenance" carried out by airline crews.

It was also recently discovered that the Japanese government loosened safety regulations for the 787 Dreamliner back in 2008 in an effort to speed up the aircraft's deployment within the country.

Source: Flightglobal



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

By Jeffk464 on 1/30/2013 6:44:33 PM , Rating: 2
argh

ground cart to start the engines

F15's and 16's cant be started without ground equipment, its really not a big deal.


By GreenEnvt on 1/30/2013 10:37:46 PM , Rating: 2
Great in most cases, but then the plane is limited to airports with that infrastructure.

Also, then you are f'd when the engines shut down in flight and you want to restart them. There have been several cases where hundreds of lives were saved because the engines could be restarted in flight after a failure.


By Jeffk464 on 1/31/2013 12:12:08 AM , Rating: 2
Ram air, you use the forward motion of the plane to get the engines spooling up to starting speeds. If the plane hasn't fallen out of the sky its engines are no doubt already spinning up to speed. If I remember right you only have to spool them up to about 30% of their operating speed to get them started.


By sorry dog on 2/4/2013 11:12:20 PM , Rating: 2
The minimum speed required for a windmill start maybe (and probably is) quite a bit higher than the best glide speed.

...and parameter for one engine operation may leave a narrow margin for windmill start of the other engine.

Regardless...the batteries are not used to start the main engines. They are used to start the APU and provide emergency power to things needed at all times like flight controls and high tech computerized glass cockpit in 787 (that would probably take 10 minutes to reboot is power were disrupted). Once the APU is running, an 1100 HP Sunstrand unit in the 787, then that can start the starter/generators on the main turbines.

Of course it was the batteries for the APU that had problems in one the JAL flights....


By sorry dog on 2/4/2013 10:50:04 PM , Rating: 2
Not a big deal in the F16....until you have to pump the hydraulic accumulator 300 times for one shot at the restart...


"Nowadays you can buy a CPU cheaper than the CPU fan." -- Unnamed AMD executive














botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki