Stress in aircrafts landing gear

• marcus91
In summary, the conversation discusses the calculation of stress in the landing gear of an aircraft for a physics coursework presentation. The formula for stress is mentioned and the questioner is seeking figures for the force and cross-sectional area of the landing gear. A website is suggested for reference and some rough estimates are calculated for a Boeing 747 and a Boeing 737. The accuracy and validity of the calculations are questioned and alternative suggestions are made.
marcus91
Hi I am doing a physics coursework presentation, and i need to calculate the stress in the landing gear of an aircraft. It can be any aircraft I just need some figures, for instance the force on the landing gear as it lands, and the cross-sectional area of the landing gear.

The formula for stress = force / area
so does anyone know a particular aircrafts force when it lands, and the area of the landing gear? If you know a website with data on this or other helpful info. please let me know what it is.

I could state the stress on the landing gear whilst on the ground stationary, but this would require the area. For the boeing 747 i know the maximum takeoff weight is 396890kg so i could use this figure but still need the area. Many thanks in advance

Google is your friend http://www.aoe.vt.edu/~mason/Mason_f/M96SC.html

Last edited by a moderator:
Hi thanks for the reply, do you know which chapter or page I should look at? thanks for this though its useful.

I also found a few other figures out now:
max weight of B747 = 396890, so max force would be this x9.8 so i got 3889522N

for the area i found a website http://www.malabar.com/pdf/product/axle/sd65P10AR.pdf stating cyclinder diamater is 8 inches, which is about 20cm. So therefore the cross-sectional area would be about 0.0314159265 msquared

so now one divided by the other gives about 123,807,330 Pa. But this would be across the 5 main landing gear sets so the stress on landing gear of B747 when stationary is about 24761466 Pa or about 25MPa. Does this seem an appropriate figure?

Last edited by a moderator:
Another ball park estimate is that the tire pressure is about 150psi which is 1Mpa so 25Mpa in the gear seems reasonable.

Generally there is almost no weight (5%) on the nose gear - just enough to provide some friction for steering.

Boeing provide detaile dspecs on their aircraft and the airport and servicing requirements start here http://www.boeing.com/commercial/overview/overview3.html

Last edited by a moderator:
hm ok thanks, I decided I would use a B737 now instead, but the cyclinder diameter is supposed to be the same as the website http://www.malabar.com/pdf/product/axle/sd65P10AR.pdf states it is used in main landing gear. A B737 only has 2 main landing gears sets and a nose gear. If i took the max weight to be about 70080kg, and the area of the cylinder at 0.032365 Meters squared, then the stress would work out at

21219649.797Pa, or about 21MPa, but this is across the two main landing gear so approximate stress would be 10.5MPa

so firstly does this number seem more accurate for the landing gear?
do my calculations make sense?
and are my choices of the cyclinder Cross-sect-area best to look at stress of landing gear?

Thanks for all your help let me know any suggestions or whatever ... thanks

Last edited by a moderator:
The pdf is for a jack not the actual landing gear, the 737 probably has smaller diamter cylinders than a 747.
And it would be more normal to say that the stress is 70t / 2*0.3m^2, and use the total area.

1. What is the main cause of stress in aircrafts landing gear?

The main cause of stress in aircrafts landing gear is the impact and weight of the aircraft as it lands on the runway. This puts pressure and strain on the landing gear components, such as the tires, wheels, and struts.

2. How is stress in aircrafts landing gear tested and measured?

Stress in aircrafts landing gear is tested and measured using various methods, such as strain gauges, load cells, and finite element analysis. These tools allow engineers to accurately measure the stress levels in different components of the landing gear.

3. Can stress in aircrafts landing gear cause failures?

Yes, excessive stress in aircrafts landing gear can lead to failures, such as fatigue cracking, buckling, and deformation of components. This is why it is crucial for landing gear to be designed and tested to withstand the expected stress levels during landings.

4. How do engineers reduce stress in aircrafts landing gear?

Engineers use various techniques to reduce stress in aircrafts landing gear, such as optimizing the design to distribute the load evenly, using high-strength materials, and implementing shock-absorbing mechanisms. They also conduct thorough testing and analysis to identify potential stress points and make necessary adjustments to the design.

5. Are there any regulations or standards for stress in aircrafts landing gear?

Yes, there are regulations and standards set by aviation authorities, such as the Federal Aviation Administration (FAA) and European Aviation Safety Agency (EASA), for the design and testing of landing gear. These regulations ensure that aircrafts landing gear can withstand the expected stress levels and maintain the safety of the aircraft and passengers.

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