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Weight Distribution And Balance On The ERJ-145  
User currently offlineHorus From Egypt, joined Feb 2004, 5230 posts, RR: 59
Posted (9 years 5 months 1 week 1 day 12 hours ago) and read 7256 times:

I just have a quick (probably stupid) question regarding how the weight distribution and balance are maintained on the ERJ-145/135.

The cabin configuration is 1-2 as shown in these photos:

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How is the balance maintained when you can have upto double the weight on the right side of the jet compared to the left?

Do they load cargo and luggage on the left? What if the flight is full in both the passenger cabin and cargo hold?

Now I realise this question is probably quite trivial and stupid so no sarcastic remarks please, just a simple explanation will suffice. Thanks in advance

Horus


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16 replies: All unread, jump to last
 
User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 1, posted (9 years 5 months 1 week 1 day 9 hours ago) and read 7199 times:

I've wondered the same thing about the MD-80 and it's variants with 2+3 seating configuration, but just figured that the explaination must be so simple or fundamental that it would eventually come to me. It hasn't, and I give up.

O



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User currently offlinePPVRA From Brazil, joined Nov 2004, 8958 posts, RR: 40
Reply 2, posted (9 years 5 months 1 week 1 day 8 hours ago) and read 7190 times:

Good question. My guess is that they can balance it with fuel... otherwise I don't know.

PPVRA



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User currently offlineCRJ200Mechanic From United States of America, joined Feb 2005, 204 posts, RR: 2
Reply 3, posted (9 years 5 months 1 week 1 day 8 hours ago) and read 7188 times:

My guess is the fuel too. I'm pretty sure the cargo hold is on the left side, so I'm sure that helps too


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User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5
Reply 4, posted (9 years 5 months 1 week 1 day 6 hours ago) and read 7173 times:

There is no balancing with fuel or cargo load. The aisle seats on the r/h side are very close to the centerline which will not produce any noticeable lateral imbalance.



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User currently offlineHorus From Egypt, joined Feb 2004, 5230 posts, RR: 59
Reply 5, posted (9 years 5 months 1 week 1 day 6 hours ago) and read 7167 times:

Troubleshooter, yes its 'close' to the cetreline but its not actually on it (most of the seat is positioned to its right) so wouldn't there still be siginificantly more weight on the right?



Horus



EGYPT: A 7,000 Year Old Civilisation
User currently offlineUSAFMXOfficer From United States of America, joined Nov 2004, 174 posts, RR: 0
Reply 6, posted (9 years 5 months 1 week 1 day 4 hours ago) and read 7157 times:

OK....if you put a 200 lb person in each seat and figure out weights and moments, you determine that the lateral CG shifts 3 inches off the centerline (to the side with 2 seats) because of the seat configuration.

This is negligible, and is not countered by "shifted baggage" or fuel.

I would wager that a lateral cg shifts several inches to either side of centerline throughout a flight, due to fuel shifting, pax movement, etc.

Not an issue.



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User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 7, posted (9 years 5 months 1 week 18 hours ago) and read 7124 times:

Like any aircraft, it must be loaded within limits. You can't fill the B and C seats with the A seats empty. After that, though, it's likely easy to keep level with aileron trim.

The only stupid question is the one that isn't asked. I've wondered the same thing often, especially when flying American, as I always get an MD-80 to DFW, then an ERJ to the smaller destination city.



Position and hold
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 8, posted (9 years 5 months 1 week 16 hours ago) and read 7114 times:

Left to right balance is just not that big of an issue when the moments are that close to a center line.... unless the difference is that drastic. Fwd and aft are the key and critical weight and balance figures with any aircraft. Besides, you can always kick in a little aileron trim to make up the differance.


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User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5
Reply 9, posted (9 years 5 months 1 week 10 hours ago) and read 7083 times:

I know some Avro RJ operators with a 2+3 seat config. It´s the same issue. No noticeable lateral imbalance which requires trimming with fuel or cargo. I don´t even think that it requires extra aileron trim.

Just keep in mind that in case of a fuel imbalance the applicable warning is given at an imbalance of a few (I don´t have actual values at the moment) hundred kilos. Before that it might not affect the aircraft handling in a dangerous matter.



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User currently offlineLoggat From United States of America, joined Feb 2000, 666 posts, RR: 0
Reply 10, posted (9 years 5 months 2 days 13 hours ago) and read 6968 times:

Quoting Troubleshooter (Reply 9):
Just keep in mind that in case of a fuel imbalance the applicable warning is given at an imbalance of a few (I don´t have actual values at the moment) hundred kilos. Before that it might not affect the aircraft handling in a dangerous matter.

800 lbs in the ERJ-145



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User currently offlineStarlionblue From Greenland, joined Feb 2004, 17029 posts, RR: 67
Reply 11, posted (9 years 5 months 2 days 13 hours ago) and read 6957 times:

Same with the DC-9 and the MD-80/90. The shift in CG is so small as to make no difference.


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineKAUSpilot From United States of America, joined Jan 2002, 1958 posts, RR: 33
Reply 12, posted (9 years 5 months 2 days 12 hours ago) and read 6948 times:

I've never had to use aileron trim in this airplane. In addition, the galley equipment is all on the right side of the aircraft, and most of the bags are loaded toward the right side since the door for the rampers to get in and out of is to the left. On the other hand, the APU does burn fuel out of the right side fuel tank, so it's not uncommon to take off with 100 lbs or so more fuel in the left than the right.

Still, when you're talking about a 50,000 lb airplane, having the CG a couple of inches off centerline doesn't make a noticeable difference.


User currently offlineJetskipper From United States of America, joined Jun 2001, 393 posts, RR: 0
Reply 13, posted (9 years 5 months 2 days 12 hours ago) and read 6953 times:

As an Embraer captain in the US with over 3300 hours of Embraer flight experience. I can attest that balance along the lateral axis is never of concern. The slight misbalance from left to right can be easily overcome by a slight airleron trim input. As was stated earlier the max fuel imbalance is, I have flown aircraft with imbalances of upto 700 pounds with no adverse flight characteristics.

User currently offlineLoggat From United States of America, joined Feb 2000, 666 posts, RR: 0
Reply 14, posted (9 years 5 months 2 days 7 hours ago) and read 6922 times:

Quoting Jetskipper (Reply 13):
I can attest that balance along the lateral axis is never of concern

I assume you meant to say the longitudinal axis? That being the axis that goes from nose to tail, of which lateral balance is pivoting/rotating on.



There are 3 types of people in this world, those that can count, and those that can't.
User currently offlineMrocktor From United States of America, joined Jan 2005, 1668 posts, RR: 50
Reply 15, posted (9 years 4 months 2 weeks 5 days 11 hours ago) and read 6787 times:

Quoting Loggat (Reply 14):
assume you meant to say the longitudinal axis? That being the axis that goes from nose to tail, of which lateral balance is pivoting/rotating on.

Although literally speaking you are correct (as the axis the aircraft rolls around is longitudinal as you described), traditional aeronautical terminology is:

longitudinal axis = pitch
lateral axis = roll


User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5
Reply 16, posted (9 years 4 months 2 weeks 5 days 2 hours ago) and read 6744 times:

Quoting Mrocktor (Reply 15):
Although literally speaking you are correct (as the axis the aircraft rolls around is longitudinal as you described), traditional aeronautical terminology is:

longitudinal axis = pitch
lateral axis = roll

That´s not correct! The movements along the three axes are as follows:
longitudinal axis = roll (controlled by the ailerons)
lateral axis = pitch (controlled by the elevator)
vertical axis = yaw (controlled by the rudder)

So Loggat was correct in reply 14.



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