ROVER WHEELS: Monitoring changes over time, NOTE: Read back through the thread to avoid repeating misconceptions |
ROVER WHEELS: Monitoring changes over time, NOTE: Read back through the thread to avoid repeating misconceptions |
May 16 2013, 08:35 AM
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#1
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Junior Member Group: Members Posts: 22 Joined: 10-August 12 From: Australia Member No.: 6530 |
[MOD NOTE: This thread follows on a post by Ed Truthan containing a MAHLI mosaic of MSL wheels taken on sol 275.]
Ed: zooming in on that marvellous underbelly MAHLI montage, there appears to be further (and previously noted) deformation of the wheel surfaces. Damage is most evident in the view of the front-left wheel inner surface. Such wear has previously been discussed and concerns allayed. Nevertheless, the front left wheel surface *appears* to have been punctured. We've only done 700 meters, and have 7000 more to get to Mt Sharp..... Given that more odometry has now accumulated, is any (re-)new(ed) concern valid? DeanM |
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May 19 2013, 01:46 AM
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Senior Member Group: Members Posts: 3009 Joined: 30-October 04 Member No.: 105 |
The likely failure point will not be on the wheel tread surface itself, but at the annulus on the inner surface where the wheel spokes attach to the wheel.
--Bill -------------------- |
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May 19 2013, 02:18 AM
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#3
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
The likely failure point will not be on the wheel tread surface itself, but at the annulus on the inner surface where the wheel spokes attach to the wheel. I'm not following your reasoning; the entire tire is one piece of aluminum, beefed up where the flexures attach. Maybe the slide I referenced will be useful. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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May 20 2013, 11:54 AM
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Forum Contributor Group: Members Posts: 1374 Joined: 8-February 04 From: North East Florida, USA. Member No.: 11 |
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Oct 7 2013, 02:33 AM
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#5
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Junior Member Group: Members Posts: 43 Joined: 13-June 08 Member No.: 4206 |
The MER and MSL builders got a lot of things right when they put them together. I'll assume they know what they're doing with the wheels.
Correct me if I'm wrong: I understand the punctured aluminum is little more than soda can thickness and provides little or no structure strength. I understand the cleats are considerably thicker and beefier and it is these that provide shape and strength. I understand that the wheel motors are insanely high torque and could rotate the wheels if they were triangular shape. I also assume that the wheels (initially with full undamaged surface area) would tend to float on dust and other lightly packed terrain. This I assume will change over time as the thin aluminum gets punched out and ripped up. Now you have less surface area, and the cleats will tend to sink more easily in sand. And at the same time, this digging-in would provide excellent traction. And perhaps even better traction when challenged against more rocky material. Make no mistake, I was horrified to read about this! But if what I said is true, and I'm right, and the builders did their job, then there's nothing to worry over. |
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Oct 10 2013, 01:32 PM
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#6
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
I also assume that the wheels (initially with full undamaged surface area) would tend to float on dust and other lightly packed terrain. This I assume will change over time as the thin aluminum gets punched out and ripped up.... Remember - the wheels were built with several large holes in them....that spell JPL in morse code. They make little to no difference to traction or surface pressure. Remember - it's 899kg across 6 wheels each with basically the same surface contact patch. It wont change significantly with a few dings and dents in it. However - your conclusion "the builders did their job, then there's nothing to worry over" is 100% accurate. |
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Oct 18 2013, 11:16 PM
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#7
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Member Group: Members Posts: 105 Joined: 27-August 05 Member No.: 479 |
Remember - the wheels were built with several large holes in them....that spell JPL in morse code. They make little to no difference to traction or surface pressure. Remember - it's 899kg across 6 wheels each with basically the same surface contact patch. It wont change significantly with a few dings and dents in it. However - your conclusion "the builders did their job, then there's nothing to worry over" is 100% accurate. I would love to see the machinery used to fabricate the wheels |
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