Re: Thrust Line & Bellyboard
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JohntenHave <Jtenhave@...>
Joseph,
Do not guess. let me give you an outline of how to calculate what you need. Firstly work backwards from what it does (or more accurately) what you want it to do. In this case deploy and slow the aircraft down. So work out the area, and how fast it could inadvertently be deployed (do not be tempted to think this will never happen to me!). That will give you the load to be reacted. Guess high speed. Assume opens at 90 deg to airflow. The Safety factor is then applied to the load. Say 2.5. Next figure out how the loads will flow, i.e. from the uniform distributed load on the plate to the attachment points and the actuator attachment. Next trick is to analyse the loads at the concentration points for the load cases, eg shear around the head if you are trying to pull the bolt through the material, compressive stress if you are trying to load the fastener in shear, edge distance analysis for failure due to pull out, etc, get the picture? Put sufficient material in place to react the safety factored load. Then consider the whole plate as a beam attached with a pin joint at one end and a simple support at the actuator and consider the bending lengthways and across the beam. Make sure the load does not exceed the allowables for hand layup. Next port of call is to put your feet on the desk and think about failure modes, what could happen if it broke? If it broke, where would be the best place for it to break? If you were in a crash and it was deployed would it spear you or would you prefer it to break before it got to you? Then think about where the loads go in the fuselage, With this sort of thing, it is often better to make sure that the parent structure does not fail under limit load whilst the airbrake remains intact. i.e match the strengths or deliberately design the part to fail first. Then lay out the materials to meet the requirements. As a flat sheet you might well find that for most of the loads that the part sees, it is too strong but it is simpler to make, and light enough to tolerate. Last check, reverse engineer what was done before as a cross check ( and be prepared for a few revelations...) Hope this helps John -- In Q-LIST@..., "Sam Hoskins" <shoskins@m...> wrote: I would do the layup on the unblemished belly. After that's done,then dig out the foam per plans. I have now idea about the orientation.Maybe one of our composite engineers could chime in.1/8" foam, then vacuum bag the layup. Any idea on orientation of the carbonfiber cloth, i.e., front to back, side to side, 45 deg. ? I have neverused carbon fiber cloth. Should it be Uni or Bid?<http://us.ard.yahoo.com/SIG=129lkt5td/M=298184.6018725.7038619.300117 6/D=gr oups/S=1705065618:HM/EXP=1109899209/A=2593423/R=0/SIG=11el9gslf/*http: /www.n etflix.com/Default?mqso=60190075> click hereM=298184.6018725.7038619.3001176/D=groups/S= :HM/A=2593423/rand=326108325> |
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