Difference between revisions of "Strix StratoSurfer Motor Mount Design Study"

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The photos below show a typical failure.
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==== Typical Failure ====
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The photos below show where the foam will "tear" and an actual failed mount.
 
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If there was some kind of structural tie-in to the wing mount bolts it would be considerably stronger. Below is an illustration of just one idea for a stronger part to be embedded into the foam. <br>
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== See Also ==
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{| border="0" cellspacing="1" cellpadding="1" width="800" align="center"
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:* [[Strix StratoSurfer Twin Conversion]] {{Star}}'''NEW'''{{Star}}
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:* [[Parts Catalog - Strix Stratosurfer]]
| align="center" | [[File:SS125.jpg|700px]]
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:* [[Current Parts Catalogs]]
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:* [https://www.thingiverse.com/markqv/designs Thingiverse Design Page]
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=== Comments? Questions? ===
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:'''<u>[mailto:qmar80@hotmail.com?Subject=About%20The%20Strix%20Stratosurfer%20Design%20Study&body=Question? email me!]</u>'''
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[[Category:Contents]]

Latest revision as of 14:31, 5 March 2019

Introduction

This page is written to support my findings with regards to modifying the motor mount structure and durability on the Strix Stratosurfer. This applies to motor mounts which have been modified with an offset mount plate to gain clearance for a larger prop and motor. In no way should this write-up be construed as a negative comment or complaint about this excellent model.

Design

The stock mount has very little foam in cross section to support the plastic mount pieces and the motor so any additional weight or leverage will put this foam piece under enormous stress. Below are some general sketches and some photos of an un-assembled stock foam mount to illustrate where weakness shows up when modifying the mount for a larger motor/prop.

SS121.jpg
Cross section showing where the mount might fail with an offset plate mount


Below you can see the difference in how load forces are applied with a hard landing or sudden stop of the airplane. In the top view of the stock configuration, the applied force goes through the mount foam compressing it but not creating a serious bending moment. In the bottom sketch you can see that by raising the motor via an offset plate, the applied force line is well above the supporting foam structure creating a serious bending moment around the weakest part of the mount.

SS121B.jpg
Application of forward forces on landing


Typical Failure

The photos below show where the foam will "tear" and an actual failed mount.

SMB7.jpg


SMB5.jpg


SMB6.jpg


Below is a picture of a failed mount showing how small the area of foam support is. The area highlighted in yellow is all that supports the motor and the motors center of mass is above the weakest part of this support putting it in an extreme stress condition anytime the plane comes to a fast stop.

SS123.jpg



See Also



Comments? Questions?

email me!