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AA-SM-291
AA-SM-290 – Lap Splice Load Distribution. Free Engineering Spreadsheet In association ...
AA-SM-290
AA-SM-290 – Doubler Load Distribution. Free Engineering Spreadsheet In association with ...
AA-SM-026-122
AA-SM-026-122 Beam Analysis – Compression Flexure – Fixed One End, ...
AA-SM-026-121
AA-SM-026-121 Beam Analysis – Compression Flexure – Fixed One End, ...
AA-SM-026-120
AA-SM-026-120 Beam Analysis – Compression Flexure – Fixed Both Ends, ...

## Popular Items

### AA-SM-503

• Version
• 267.97 KB File Size
• 3 File Count
• March 13, 2016 Create Date
• June 19, 2019 Last Updated
Scroll for Details

Free Engineering Spreadsheets: Loads - Simple Landing Gear Loads. Note that the spreadsheet cells with blue ink are the input values - all other cells are either text or values generated by the spreadsheet

19 June 2016 - Rev B uploaded. Correction of reference lengths.

6 November 2016 - Rev A uploaded. Correction of some mass terms to reference input data.

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### AA-SM-503

• Version
• 267.97 KB File Size
• 3 File Count
• March 13, 2016 Create Date
• June 19, 2019 Last Updated
Scroll for Details

Free Engineering Spreadsheets: Loads - Simple Landing Gear Loads. Note that the spreadsheet cells with blue ink are the input values - all other cells are either text or values generated by the spreadsheet

19 June 2016 - Rev B uploaded. Correction of reference lengths.

6 November 2016 - Rev A uploaded. Correction of some mass terms to reference input data.

FileAction

## 11 thoughts on “AA-SM-503”

1. alex says:

Hello. Thank you very much for the preparation and free distribution of this lengthy calculation. I would be obliged if you could give me your opinion on the following:
i) Is there an empirical or analytical way to calculate the vertical distance of the cg (Hcg) from a given reference point (say ground)?
ii) How did you calculate the Iyy? Does this apply to a 2d cross section of the aircraft or to the 3d aircraft as a whole?
iii) In the end you have “+ or -” on some of the force results. This is to show that their direction depends on the axis system set by the analyst?

Thank you very much for your assistance.

1. Richard Abbott says:

Hey Alex – I will reply to your questions as best I can

i) the CG position of the aircraft is calculated or estimated based on the aircraft mass distribution – the distance from the ground to the CG position is a function of the height of the gear and the position of the aircraft CG. There is no short-cut to get to this other than an educated guess.
ii) The Iyy is the mass moment of Inertia of the aircraft around the Y axis – again this is arrived at from either a calculation from the aircraft mass properties. It can be estimated and there is a method and data in Roskam (ROSKAM, PART V, CHAPTER 3) that will help you – this is available in one of our spreadsheets here
iii) Yes – is it normal to be positive aft (x), positive up (z) and positive right (y)

Good luck!

1. alex says:

2. alex says:

Hello again. I am sorry to ask, but I have a question with respect to the airplane mass used on 23.485 (side load conditions) calculations. It appears that for the max. fwd cg case mass, max aft cg mass, max. landing mass and min.weight the mass used is a percentage of the mass used in the static case calculation (Different on each case).

I looked on the respective FAR 23 article and I couldn’t find anything related to these percentages. Could please explain how they appeared in your calculations?

Thank you very much for your kind assistance.

1. Richard Abbott says:

Alex – my apologies. this is an error in the spreadsheet. Revision A has existed for some time and it did not get uploaded. I have uploaded it to this library page and now the side load conditions reference the input aircraft mass values at the start of the sheet.

1. alex says:

1. Richard Abbott says:

We rely on the help of the engineers using our sheets to iron out our own imperfections! Thanks for your vigilance and professionalism.

3. alex says:

Hello! Has anyone thought to provide similar calculations covering the FAR 25 requirements? I think there are a lot of similarities. By the way, does the lift to weight ratio (L = 0.667) and the K = 0.33 (used in inclined reactions cals as arctan(K) have the same values in FAR 25? Thank you.

4. manos says:

Dear sir,

thank you for provided this free calculation. Could you please provide a reference for the calculated relative distances a’,b’,d’ (pages 4,5 of the spreadsheet)?

Thank you.

1. Richard Abbott says:

Those values are calculated using basic trigonometry and are contained in the cells. We may include the xln function to show the math in these cells in a later version. This method of splitting the load between the main and nose gear is referenced to appendix C of the FAA Part 23 regulations. Specifically this diagram http://www.ecfr.gov/graphics/pdfs/ec28se91.029.pdf

1. manos says:

16,892 Documents in our Technical Library