yahoouser
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Post by yahoouser on Jan 6, 2020 23:05:30 GMT
Bobby Clark
Mon, Mar 9, 2009, 11:35 AM
to Rocket_Belt
After reading the previous post in the "Ball Joint" thread, I have decided
to go with a Bell like design. The lowest rated ź inch spherical bearing
has an axial pull out of 7650 lbs. The rule of thumb that some of the
manufactures are using is a radial load limit of 20% or 1530 lbs. The
dynamic load rule of thumb is 1/3 of the static load. That would put axial
pull out at 2550 lbs and radial load at 510 lbs dynamic load. This seems to
be safe enough based on the flight characteristics of the typical belt. Any
thoughts on the figures or the rules of thumb mentioned?
Bobby
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yahoouser
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Post by yahoouser on Jan 6, 2020 23:05:52 GMT
Peter G
Mar 10, 2009, 10:12 AM
to Rocket_Belt
Bobby,
If you LOOK to the ball joint of an original Bell belt, it looks SCARY.
Such a tiny bolt (about 6 mm)between the corset and the 800 HP motor...
But it was good for over 3000 flights.
Peter
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yahoouser
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Post by yahoouser on Jan 6, 2020 23:06:16 GMT
Bobby Clark
Mar 10, 2009, 11:37 AM
to Rocket_Belt
Hi Peter,
Yes, I admit that I at first thought it was small. But after researching it, I think the numbers speak for themselves. I do not believe there is anyway for the dynamic or static loading to get the part to fail. I also looked at the that attachment bolt. A grade 8 bolt is good for about 4468 lbs in shear and 5009 lbs in tension. Since these bolts are good for millions of cycles of stress, I do not see how that can fail if installed properly. I think the sheet metal will tear out around the fastener head before the fastener goes. With the numbers backing up Bell, I am going to follow the Bell belt as much as possible. No point re-inventing the wheel on some things.
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yahoouser
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Post by yahoouser on Jan 6, 2020 23:06:43 GMT
Peter G
Mar 10, 2009, 10:40 AM
to Rocket_Belt
Hi Bobby
You are right.
Very anxious to see the progress on your belt.
Your pre-research is very good. No loose cannon on your belt!
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yahoouser
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Post by yahoouser on Jan 6, 2020 23:07:05 GMT
Bobby Clark Mar 10, 2009, 11:55 AM to Rocket_Belt Peter, I hope not. There are deviations in my belt, but not on the bits like this. I had to agree to a few terms and conditions for my wife to agree and let me go after this dream. One of them is not to get seriously hurt or killed.  I should start bending metal before April. I am going to miss my April target for first flight, as I have another commitment due in May. Perhaps by the summer. |
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yahoouser
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Post by yahoouser on Jan 6, 2020 23:08:01 GMT
Peter G
Mar 10, 2009, 1:15 PM
to Rocket_Belt
Thanks Bob, and good luck with building.
Remember that SAFETY is the main goal when you build a belt,
You promised your wife, and you know what you get when you do not hold your promise to your wife :-))))
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I should start bending metal before April. I am going to miss my April target for first flight, as I have another commitment due in May. Perhaps by the summer.