Is my landing gear design suitable for the cyclone airplane?

Click For Summary

Discussion Overview

The discussion revolves around the suitability of a landing gear design for the Cyclone airplane, focusing on analysis related to material selection, stress calculations, and fatigue considerations. Participants are examining technical specifications and requirements for the landing gear under specific loading conditions.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • The initial design parameters include an aircraft mass of 43000 lbs, landing speed of 65 knots, maximum deceleration of 3g, and a factor of safety of 1.5.
  • One participant calculated the force in the Y direction as 516.115 kN and in the X direction as 238.555 kN, but found a high stress value of 40190 N/mm² in their analysis.
  • Questions were raised about the cross-sectional dimensions, area, moment of inertia, and the length of the part, as well as the number of stress cycles per landing.
  • Another participant inquired about the specific material name for H950, suggesting it might refer to hardness rather than a material designation.
  • Clarifications were requested regarding the input units for calculations and the output display units in the analysis software.
  • The material was identified as Hardening Stainless Steel bar, specifically AMS 5629 (13/8 PH VAR), but uncertainty remained about how to incorporate the number of landings into calculations.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the calculations and material suitability, with ongoing questions and clarifications indicating multiple competing views and unresolved issues.

Contextual Notes

There are limitations regarding the assumptions made in the calculations, the dependence on specific material properties, and the lack of clarity on how to factor in the number of landings for fatigue analysis.

gimini75
Messages
50
Reaction score
0
Hello

I have an assignemt to analysis a landing gear for the cyclone earoplane, an initial design being supplied, I have being askedto check for the suitability of the part, the conditions are:

Aircraft mass with fuel: 43000 lbs
Landing speed: 65 Knots
Maximum deceleration: 3g
Each part takes 25% of the landing load (see the picture attached)
External diameters cannot be exceed or pitch between lug centres changed.
Factor of safety for landing load: 1.5
Maximum number of landings: 500000

Here what I have done, I converted all units to (N, mm), the mass of the aeroplane is (0.45 x 43000 = 19350 Kg), speed (=65 x 0.514 = 33.41 m/s), Force (= 19350 x 3g = 564.47 kN), I found force in Y direction = 516.115
X = 238.555 kN (Fx=Fcos25), but when I run the vo mises ProMechanica analysis I found (40190 N/mm2, which is to high as I have to choose a material from a list provided to me, the max is (H950 with 1517 MPa), now I don't understand what mistake I have made for my analysis, I appreciate any help from you.



Thanks
 

Attachments

Last edited:
Physics news on Phys.org
(1) What are the cross-sectional dimensions, cross-sectional area, and moment of inertia of the part? (2) What is the length of the part? (3) How many stress cycles, n, occur per landing? (4) What is the fatigue strength of H950 at 500 000*n stress cycles? At least answer items 1 and 2.
 
Hi

Thanks for your reply, I have attached the dimensions of the landing gear which you asked for.

Thanks
 

Attachments

Last edited:
gimini75: What is the name of the material for H950? I think H950 is the hardness. But what is the name of that material?

Ensure all of your input units are N and mm, not kN. Ensure your software expects all input values in N and mm. Also, see if your output display is showing MPa or Pa. Is your output display showing units of MPa or Pa?
 
Hi

The materials is Hardening Stainless Steel bar, all my units are in N and mm, just one thing else I don't know how to use the number of landings in my calculations as I don't have any other information about it.


Thanks
 
Give us the name of the stainless steel material. Which stainless steel? Also, please answer my last question in post 4.
 
Hi

The materials is AMS 5629 (13/8 PH VAR).

Thanks
 

Similar threads

Corrugated tube (bellow) under axial load
  • · Replies 2 ·
Replies
2
Views
2K
Load analysis on a motorcross bike - need some advice
  • · Replies 5 ·
Replies
5
Views
2K