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I recently had to create a V-n diagram spreadsheet for a loads report we are working on for a client. This is for part 23 aircraft and is based on the utility category maneuver envelope, but it does show the normal category envelope for comparison. You can download the free spreadsheet here Enjoy!

We have updated the lug methods for our engineering textbook and one of the best explained and best laid out classic lug analysis comes from the US Airforce Stress Manual, AFFDL-TR-69-42  and is explained in our online textbook here. We have used this as the basis for our lug analysis spreadsheets. All of the curves are fully […]

It has been a few weeks since we posted any new analysis spreadsheets. We have been busy getting the check version of the engineering textbook ready for the mailing list subscribers which was finally released in the June newsletter. Along the way we did manage to create some analysis spreadsheets of the membrane analysis methods in […]

  This is an update to a previous post here. During further background reading I came across this reference ARC-RM-2588 which gives a more detailed method for developing spin-up loads for aircraft landing gear. When I get time I will see if it is worth adding as an alternative spreadsheet method to the library and run […]

We had to design a set of belleville washers for a client last year so we had to go and find a useful design criteria. NASA came to the rescue this time. In (NASA TM X-73305, 1975) there is a simple method for sizing and behaviour of disc springs. The behaviour of disk springs is non linear […]

There is a relatively simple method in the FAR part 23 appendix for calculating rational landing gear spin-up and spring-back loads. This method is referenced to and better explained in NACA-TN-863 which also has some other very interesting and useful data. This Spreadsheet has a method for calculating the rational horizontal loads for the part […]

Again, NACA provides a the solution to another problem. The theoretical derivation of plate compression buckling coefficients. I had a simple derivation, which uses this equation for the simply supported  plate buckling coefficient NACA-Report-733 has the expression that give the general curve for any edge restraint condition: The free spreadsheet is available here and has the simple expression […]

A note on Google. We love Google – we use Google as the backbone for our company communications and Google hangouts makes a lot of what we do possible. But since we moved from Canada to the Cayman Islands we have had trouble getting our Google maps entry to update correctly. First we were not able […]

Yet again NACA shows what a remarkable set of work it really is. I am going through the buckling of isotropic design features for our Stress Analysis book. Almost every time I need a derivation from first principles or the mathematical basis for a set of design curves NACA does not disappoint. In this case I […]

One of the basic building blocks of any stress analysis is material data. It is one of the 3 basic parameters of material, geometry and loads that are required for a stress analysis. I wrote the first version of the spreadsheet 15 years ago and it has been updated and improved over time. It automatically […]

Earlier posts here and here, Prompted by my colleagues in the industry I posted my comments to the FAA – the text of my submission is duplicated below and there is a link to the pdf document of the same at the end. After further consideration I have come to the conclusion that the change to […]

This post here looks at the a public domain method for the strength of potted inserts – However it is very important to note that the two main references for these methods are flawed in some way. This is the introduction from our (soon to be released for draft review) free engineering textbook: This chapter […]

I wrote something initially in this blog post post on this subject. This month I have had discussions with several of our clients regarding the new part 23 regulations. From the reviews we have done the technical content and definition of requirements looks to be either unchanged or improved. However, the change to the public […]

As we go through the process of up loading all of our reference data to the library we can also complete uploading the linked and referenced spreadsheet methods. We have just uploaded our ECSS references so we have linked and uploaded our potted insert analysis spreadsheets. AA-SM-140 Composites – Potted Insert Strength – Key Parameters AA-SM-140-001 Composites – Potted Insert Strength […]

This is a follow on to the previous post of the FPL reports here. We have taken the derivation for the sandwich compression panel buckling coefficient and made it available in spreadsheet form. We have also started to upload our general set of sandwich analysis spreadsheets. These spreadsheets are numbered AA-SM-102-XXX and include AA-SM-102-001 – Composites – Cored Laminate Basic […]

I took our tension clip spreadsheets off line while I derived a theoretical method that matches the leading OEM tension clip analysis strengths. That was an interesting process……… The full derivation will be in the up coming free text book. The three spreadsheet methods are available here: AA-SM-027-003 Tension Clips – Formed Aluminum – Abbott Aerospace […]

You can read the first three posts in this series here: Post 1, Post 2, Post 3 There are limited options for dealing with a hole in a shear web. There is a often used ESDU reference for this situation. ESDU sheets are a commercial product and unless you, or your organization have paid for […]

You can read the first two posts in this series here: Post 1, Post 2 When you calculate a buckling allowable that is beyond the material shear yield stress the allowable is unrealistic. For shear buckling this can be particularly problematic as the shear yield strength is not typically given in the common material data set so […]

To refine the simple buckling analysis in the first post you can take account of the panel edge fixity and account for material non linearity. This post concerns how to take account of panel edge fixity. The method I prefer is defined in (NACA-TN-2661, 1952), this reference is the grand daddy of aircraft buckling source material. This paper […]