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Old Jan 19, 2013, 05:33 PM
Intermediate Multi
Trisquire's Avatar
Columbus, OH
Joined Mar 2005
3,338 Posts
Quote:
Originally Posted by CurrentDude View Post
It's really sad to read this thread. We're i.e. model flying pilots are supposed to be more techno savvy than a guy on the the street and yet revealing our lack of knowledge.... and allowing tabloid papers to tell us about science... outrageous.
Who's telling anyone anything about anything?
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Old Jan 19, 2013, 06:00 PM
Location: The Flightline
ssautter's Avatar
United States, OR
Joined Feb 2011
394 Posts
This thread is overblown

All lithium batteries are not created equal.

Voltage to the receiver and servos, or other full-scale systems, is more important than the uninformed bias of any given pilot, A&P, or operator.

If the servos you run in your sailplane, aren't rated for any voltage above 4.8V, then don't use Lithium batteries without a regulator or voltage booster.

Also, NiCads and NiMH batteries are not "ancient technology".
Many gasser ignition engines specifically recommend 4.8 volts to the module and plug.
Adding a voltage regulator is impractical in many modelling applications.

It's entirely possible to use unregulated A123s, Li-Ions, and LiFePO4s for receiver power; but, these packs can display a voltage of over 7.2-7.4V, immediately after charging.
Receiver brownouts or premature servo failure is inevitable.

The long-chain molecules (i.e. polymers) in LiPo batteries are what makes them the most volatile of the Lithium types.
Once again: All lithium batteries are not created equal.

Many combustible fuels are also long-chain molecules (i.e. polymers) so the electric motor vs. internal combustion engine debate is completely unnwarranted.
And, all RC models require receiver batteries, regardless of the main power system. Try flying a nitro RC ship, without any batteries, and see how far you get.

The major reason (pro) for using LiPos in sailplanes is the relatively small size and light weight.
The major reason (con) for not using LiPos in sailplanes is the 3.7V/7.4V nominal voltage.

So, kwitcherbellyachin'&gofly.....
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Old Jan 19, 2013, 06:16 PM
Alphabets make great soup
Hamburglar's Avatar
Australia, QLD, Toowoomba
Joined Jul 2008
1,907 Posts
Whenever I'm sloping I use Chapstick to stop my lipos from burning.
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Old Jan 19, 2013, 06:18 PM
Right Rudder
PittSpecial's Avatar
USA, FL, Orlando
Joined Nov 2010
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Quote:
Originally Posted by Hamburglar View Post
Whenever I'm sloping I use Chapstick to stop my lipos from burning.
Ha Ha Ha!

That was funny and the cute Baby Picture Avitar as well!
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Old Jan 19, 2013, 06:25 PM
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IceRain29's Avatar
Canada, ON, Toronto
Joined Jun 2011
138 Posts
lol volt seems nice though

does volt use a giant lipo?
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Old Jan 19, 2013, 06:36 PM
Faster!
Joshua Wesley's Avatar
United States, NV, Sparks
Joined Oct 2004
1,159 Posts
I've seen NiCads and Lead Acids cause damage in business aircraft. We shouldn?'t be so quick to condemn lipos in full scale aircraft. A lot of early turbine? engine blew up and failed in flight. Look at where we are now with Turbofans and Turbo props. Takes time to perfect things.

My two cents.

-Joshua
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Old Jan 19, 2013, 07:35 PM
Crashing into the sky!
jackosmeister's Avatar
Auckland NZ
Joined Aug 2007
7,401 Posts
Quote:
Originally Posted by Joshua Wesley View Post
I've seen NiCads and Lead Acids cause damage in business aircraft. We shouldn?'t be so quick to condemn lipos in full scale aircraft. A lot of early turbine? engine blew up and failed in flight. Look at where we are now with Turbofans and Turbo props. Takes time to perfect things.

My two cents.

-Joshua
^ This.

Nicads with thermal runway make a damn big mess of planes to. Have seen it happen, and had to clean up the mess.
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Old Jan 19, 2013, 07:54 PM
"Comin down Fast"
South East Pennsylvania
Joined Jun 2007
202 Posts
Well we heard all of the negative.

I look forward to the TV news report's broadcast of how Boeing and Boeing engineer's solved the problem.

I won't hold my breath while waiting.
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Old Jan 19, 2013, 09:38 PM
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stuntflyr's Avatar
Los Angeles
Joined Jun 2010
1,410 Posts
Quote:
Originally Posted by the_canuck View Post
Ya, but if they plug the plane in while on the ground you get Japanese power on the plane.

I can see a design engineer designing the charger for balanced 3ph power and then not consider the Japanese who are one of the only countries in the world that ground one corner of a delta 3ph power. It causes all kinds of issues with 3ph power supplies. It's hard to tell what it would do to a battery charger.

Andrew
Dude,
Airplanes aren't plugged into the wall at the hotel! The ground power is the same volts and freqs as the system on the airplane or it won't accept the power. The airplane's battery charger is powered by the airplane's electrical power system, so it's just going to be a dead airplane electrically unless the proper ground power is present.
If there is no ground power, the airplane's own APU is used to power the airplane and the battery charger is still powered by the airplanes electrical system.
Chris...
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Old Jan 19, 2013, 10:25 PM
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earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
13,606 Posts
Remember the unit was built by the lowest price contractor who bid and won.
So they have literally millions of parts on the plane, all made by the lowest bidders who won the contracts to make the parts. Looks like someone maybe cut one corner too many there.
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Old Jan 19, 2013, 10:46 PM
Registered User
United States, TN, Blountville
Joined Oct 2002
3,662 Posts
What, you guys didn't forward the thread link to Boeing so they can save all that engineering time to solve this problem, since all the root causes have been exploded here, I mean explored here?
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Old Jan 19, 2013, 11:21 PM
Dean
A10FLYR's Avatar
USA, CO, Littleton
Joined Apr 2005
3,907 Posts
Quote:
Originally Posted by RAFster View Post
What, you guys didn't forward the thread link to Boeing so they can save all that engineering time to solve this problem, since all the root causes have been exploded here, I mean explored here?
Theyre already reading this thread to find a solution!!
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Old Jan 20, 2013, 12:59 AM
Where's the wind?
the_canuck's Avatar
United States, CO, Denver
Joined Jun 2004
5,877 Posts
Actually the plane does get plugged in while on the ramp at the gate. Either that or they would have to constantly run the engines to keep the lights on.

Here are the requirements:

http://www.boeing.com/commercial/aer...icle_02_3.html

Looks like 115VAC at 400Hz with 90KVA loads.

I'm just saying that the FAA may have overlooked Japan's weird power grid when approving the power circuits.

After a bit of reading the 787 uses a unique approach to power on the plane. Interesting reading if you care to look.

We all know over charging this type of battery can lead to battery failure so I was thinking of how a circuit could overcharge that would be well tested by the FAA. Well the only thought that came to mind was that it occurred in Japan which may be a factor that the design guys weren't taking into account.

I work as a quality engineer for a company that builds cabin entertainment and communications equipment for Business class aircraft. I get to troubleshoot interesting failures of our equipment on aircraft all the time. The good thing is if our equipment fails, you can't get your email or maybe not going to see the end of that blockbuster that's playing. The main batteries failing and catching fire is a much bigger deal. I used to work on industrial power supplies and Japan's power grid was always a big issue with those products.

Andrew
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Old Jan 22, 2013, 07:44 PM
Location: The Flightline
ssautter's Avatar
United States, OR
Joined Feb 2011
394 Posts
Quote:
Originally Posted by the_canuck View Post
Actually the plane does get plugged in while on the ramp at the gate. Either that or they would have to constantly run the engines to keep the lights on.

I'm just saying that the FAA may have overlooked Japan's weird power grid when approving the power circuits.

After a bit of reading the 787 uses a unique approach to power on the plane. Interesting reading if you care to look.

Andrew
Yep,

Many commercial aircraft use 24VDC systems, as opposed to the standard 12V automotive systems. Not sure about the '87....the link explains the VAC APU systems. Alternating current makes my head spin!
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Old Jan 22, 2013, 08:02 PM
Brett
bjaffee's Avatar
So Cal
Joined Apr 2002
5,311 Posts
Quote:
Originally Posted by ssautter View Post
Yep,

Many commercial aircraft use 24VDC systems, as opposed to the standard 12V automotive systems. Not sure about the '87....the link explains the VAC APU systems. Alternating current makes my head spin!
Last article I read said it uses 32V (or 34?).
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