Avid Flyer Mk IV Major Change and Upgrade


31 posts in this topic

Posted

Beef up the sides of the fuse and seat truss.  computer numbers are always better than flight reports, pics of bent fuselages and pireps hahahahaha.

:BC:

No computers were harmed in the making of this movie. All hand calculated! Notice the cabane has a cross bar at the top to reinforce the fuselage from the side forces of the upper strut. In any case, these loads look a lot like the same from the original bungee system, frankly. The biggest problem is that we have to eventually hit the ground I think.

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Posted

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Posted

I am sure you have read  this thread.  Seeing the report and pictures he wrote up really helps to visualize what I am referring to.  Its not just the loads on the fuse, but the way the bending loads are applied to the gear legs that cause the failures.  Many of the reports come from guys who did not have a very hard landing at all and bent the gear or the fuse.  The gear currently on my plane was from one such fellow.  My quick fix was the different springs that wont go metal to metal so quick.  The real fix is to incorporate Bob's findings into the new gear as well as a few other tweaks I have done after running it through the engineers here and having them run the load calcs and bending moments etc.

:BC:

 

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Posted

Without crunching any numbers, you have A drawn in at 45* to horizontal. Any upward wheel movement would be greater than outward movement from that point up, very close at that point. Were you thinking 4" spread between the two wheels? Only 2" upward movement before spring bottoming would be of great concern to me. Better buy bushwheels and keep the pressure low. ;o)

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Posted

I may have the wrong end of the stick here but when installing my Highwing cabane gear the total wheel travel appeared to be in excess of 6inches vertical(no springs and using full travel of the slot) geometry at work?

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Posted (edited)

Marcus

The angles I used are the actual ones, the upper rod is 58.5 degrees from the ground, and the lower one is 32.3. The sketch I drew is not to scale, it is for identification of the terms used. Here the dimensions and angles are correct, the drawing is just a cartoon, don't use it, just its numbers. The spring is correctly sized, the gear meets Part 23 requirements for a 8 feet per fecond drop, and the spring does not bottom on that drop, it can go to almost 4 g's before it bottoms.

 

Fitt Gear.jpg

Edited by nlappos

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