×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

*
*
*
*

Thanks. We have received your request and will respond promptly.

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!
*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

Maximum Inertial Load

thread2-425836

Maximum Inertial Load

Maximum Inertial Load

(OP)
See image. The blue & orange curves represent + ultimate load factor curves for the shorter, lighter model of a type. The grey and yellow is for the longer, heavier model of the same type for which I just have some tabulated data. Both derivatives share common cg (x394). The shorter model distribution makes sense. The grey curve for the longer model makes sense too given the higher mass moment of inertia. But I don't understand the sudden change in the three last data points represented by the yellow curve. The tabulated maximum ultimate loads for the longer model are all given from the same yz axis. The slope change does occur just forward of the t-tail horizontal stabilizer.



I think I'm missing something fundamental here - is it obvious to others?

RE: Maximum Inertial Load

you say you're comparing a shorted and longer plane, but the axis is in "fuselage station". won't it make more sense to plot in terms of normalised fuselage station (ie %age of length) ?

why does the load kick up towards the tail ? maybe ditching ? maybe dynamic landing ?

another day in paradise, or is paradise one day closer ?

RE: Maximum Inertial Load

...or "Mean Aerodynamic Chord" which is more commonly used, to amplify RB's comments.

My turn for a WAG: Fuselage elastic flex and recoil. I think an effect like that would be X^2 with length, but very small for most of the fuselage. You said this is a stretched fuselage, so maybe that effect begins to matter when it gets >40 feet from the spar.

STF

RE: Maximum Inertial Load

is the certification basis the same for both models.

It looks like 2 super imposed load cases. The gray line is 6.5G at the CG and yellow is 2.48 G so I would guess that the yellow is a pitch related load at maximum maneuvering load and the gray emergency landing maybe.

RE: Maximum Inertial Load

(OP)
Certification Basis is the same. The steep curve intercepts the main gear at 2.96g. I would think RB is right...landing load. For interest:

RE: Maximum Inertial Load

those are pretty extreme g loads (>9) ... is this commercial, or military ?

another day in paradise, or is paradise one day closer ?

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! Already a Member? Login

Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now
Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close