×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Tail Section Weight Changes and Flutter

Tail Section Weight Changes and Flutter

Tail Section Weight Changes and Flutter

(OP)
A colleague and I are at odds about how concerned we should be with regards to the dynamic effect of removing an APU from the tail section of a commuter aircraft.  The APU is a light modern design (~100lb) but is at the extreme aft location.  The mode we would be most concerned about would be the empennage vertical bending.

At what point would you be concerned about dynamic effects from a similar design change?  What would warrant investigation to you.

RE: Tail Section Weight Changes and Flutter

First of all it will change the CG - so I would be concerned right there.  After all it is 100 lbs about as far from the existing CG as possible.

How does it affect the structure - does it somehow stiffen or strengthen something?  Obviously, we don't know but depending how it is installed, it could??

RE: Tail Section Weight Changes and Flutter

(OP)
cg limits are not affected.

Mounted in isolation.  Does not carry any loads.

RE: Tail Section Weight Changes and Flutter

Then I have no clue if it will affect anything - but my gut reaction is that it will.

RE: Tail Section Weight Changes and Flutter

Check to see if it changes the natural frequency of the fuselage in yaw. With that weight removed, the frequency may go up. Then look to see if it couples with anything.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them.  Old professor

RE: Tail Section Weight Changes and Flutter

and pitch ... had a case where we had to ballast a plane ('cause sales effed up, and sold a configuration with out of bounds cg).  dynamic landing analysis showed that the ballast was going to feel Huge accelerations, way more than the rigid airplane flight envelope.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources