Many thanks to Surya Batchu for the following correction to our free textbook. At the top of Page 91 of the textbook the phrase “The interaction equation for fasteners loaded in the unthreaded shank is:” should read “The interaction equation for fasteners loaded in the thread is:”. This will be corrected in the much anticipated […]

An eagle-eyed engineer using our free textbook has spotted an error. We rely on the community of engineers who use our original and hosted materials to help us correct mistakes and improve the quality of our output. If you see anything that is incorrect or can be improved please comment on this post or contact us […]

We have taken a copy of the Part 23 regulations as they were on the 25th August 2017 and have reproduced them below: All of the regulations are included in the same page. You can use ‘find’ or ‘search text’ to find the information you want. To the best of our knowledge the ‘old’ part […]

Free Structures Analysis Spreadsheets Update: One of our stress engineers found an improvement to be made in the method for determining stress due to an interference fit bushing the difference between the material strengths for the lug and the bushing are now clear. We have also improved the layout and made it easier to use. Please update your […]

One of our users has found an error that under-predicts the peak stress ‘f’ in the disc washer. Revision C with the corrected expression for ‘f’ has been up loaded at the link below. Makes sure that you update your personal library with the latest version. AA-SM-042-001

We have uploaded our next set of free engineering spreadsheets. These are for three-member two-dimensional rigid frameworks. These spreadsheets are written by Sophia Abbott (my daughter) who is starting at Ryerson University in Toronto this year studying Mechanical Engineering (thankfully, she gets her talent and her looks from her mother). I have checked all of them […]

Thanks to the hard work of our esteemed technical librarian – Kenan Stewart – we have reached the milestone of 15000 unique items in our free technical library. We are building towards our aim of being the premier online aerospace technical reference library. We now average between 1500 and 2000 downloads per day from all over […]

Many thanks to one of our diligent readers for finding the following error in our free textbook. On page 83 of our textbook, there is a method for the pull-through strength of a bolt in a composite laminate. This contains an error with regard to the definition of the parameter ‘D’. A corrected version of […]

As part of the inclusion of a Torsion chapter in the third edition of the textbook, we have revamped and broken out the torsion of regular section analyses into different spreadsheets. This also has given us the opportunity to check and make some minor corrections. Links to the spreadsheets are below.   AA-SM-002-011 Torsion – Regular […]

These methods are only applicable to simple, traditional aircraft configurations. Part 23 Appendix A should be read in its entirety to fully understand the context of these loads methods.

Weight and thickness of sheet metal, standard thickness of sheet metal and wire. Material Specifications for Steel Sheet Metal: A366: Cold Rolled Commercial Quality A569: :Hot Rolled Commercial Quality A570: Hot Rolled Structural Quality A526: Zinc Coated (Galvanized) Steel A526/A527: Galvanneal A591: Electrolytically Zinc Plated

Download our free structures textbook and analysis manual or view the online version AA-SB-001. Machinist Drill Bit Size Table – ANSI Drill Size Chart – ISO Metric Drill Bit Size Table. Millimeter to inch conversion Fractional and Metric Sizes ref. ANSI/ASME B94.11M-1993

Minimum (minor) and maximum (major)  thread diameters, threads per inch, tap size and drill sizes. ANSI External screw thread dimensions. Installation torque values from two different sources. The data fastener thread pitch and diameter data below is taken, in part from,  from  MIL-S-8879 External screw thread dimensions from ANSI standard: Bolt installation torques are taken […]

Rivet Shear Strengths for common rivet materials, drill bit sizes and modification for sheet thickness   Rivet Shear Strengths are taken from  (MIL-HNDBK-5H, 1998) Table 8.1.2(a) and Table 8.1.2(b). These strengths are the solid rivet shear strengths and describe the shear strength of the shank of the rivet. For the double shear strength of a rivet, the […]

We are very happy to announce that the second edition of our free engineering textbook “Analysis and Design of Composite and Metallic Flight Vehicle Structures” is now available. We have also added many new free spreadsheets to our collection and now have over 200 free spreadsheets available to complement the textbook available in the Technical […]

This method is taken from our free textbook “Analysis and Design of Composite & Metallic Flight Vehicle Structures” and gives a way to calculate the shape factor in the plastic range for a ductile material. The Ramberg-Osgood Stress-Strain Curve Shape Factor in the yielding region (NACA-TN-902, 1943) can be found for most common ductile materials from  (MIL-HNDBK-5H, 1998). A more […]

This post is taken from our free textbook “Analysis and Design of Composite & Metallic Flight Vehicle Structures” and defines a method for calculating the stresses due to an interference fit bushing. The method in this section is referenced to (AFFDL-TR-69-42, 1986) Section 9.16. Note that several errors in the source material have been corrected. The […]

Recently I got pulled into some problem solving on a part 23 aircraft program. It is great to suddenly get thrown into a new group of people and try and unravel all of the technical and personal knots. These were a great bunch of engineers and it was a pleasure to spend an afternoon with them. […]

First Post – Introduction In writing our free textbook I had to make what I consider to be a huge personal and professional concession. I had to use Microsoft Word. I started out writing the book in Excel but the page formatting and section numbering and referencing issues were too great. Word is great writing […]

As we work towards the second edition of our textbook we are completing and uploading the accompanying spreadsheets. We have finally completed the simple beam analysis section of the book and the 33 spreadsheets that will accompany that chapter in the book are now written and uploaded (We will leave multi-span beams and curved beams […]