Date: Fri, 8 Aug 2008 16:02:33 -0700
Reply-To: Mike Elliott <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike Elliott <camping.elliott@GMAIL.COM>
Subject: Re: [NVC] Engineers: quick and cheerful vibration analysis?
In-Reply-To: <ac1f198b0808080941g568c4551m5d4704a4402ecd4a@mail.gmail.com>
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Well. Yes. Of course. One /could/ use such a *sniff* low tech approach.
One might as well plant a small boy back there with a video camera, Blair
Witch-style, and review the tapes later.*
There is something about your solution that I like: it appeals to my inner
R. Goldberg. But my inner Mythbuster (read: Grant Imahara) wants
accelerometers and graphs.
I, personally, would combine your approach with my approach (subjective
ball-watching v geeky graphs and stuff AND would add to it some means to
inflate/deflate the tires remotely while in motion as well as sense and
report back sidewall temperatures. I'm telling you: with sufficient
funding this could quickly mushroom into a completely absurd project!
====================
* Actually, if that wasn't so darn dangerous and illegal, it would be a
great way to evaluate tire pressure v ride harshness!
--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus -- NOW SOLD TO THE BUYER OF OUR HOUSE
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
On 8/8/2008 9:41 AM Jim Akiba wrote:
> For what you're trying to do, software, sensors and data are way
> overboard I think. Match the solution to the problem... you simply
> want to be able to verify that at X tire pressure you do or don't have
> an additional level of "bounciness" whatever that means correct?
>
> What not just grab a cheap video camera, some bungees, a plastic wide
> mouth jar big enough for a tennis ball, a ping pong ball, and a
> softball for example(you might need something much heavier/lighter
> depending on the displacement and frequency of bounce). Put the tires
> at X pressure, write that on a piece of paper and "show" this to the
> running camera(to link that tire pressure with the video with
> certainty) that is now strapped to the trailer and recording the ball
> in the see through plastic container. Ride in a set path that you will
> repeat at whatever speeds you would like. Concentrate on road safety
> and consistency in driving. Change the tire pressure a few times and
> repeat. Simply watch the tape, and "see" what you can see... You
> could likely run this test and have an idea of what you want in the
> same amount of time it would take to track down a good sensor for
> cheap, install the software, run the test, and analyze the data.. and
> I'm almost 100% certain that interpreting the simple visual data will
> be much more intuitive for your average bear than raw numbers...
> especially if you aren't sure of what range of displacements and
> frequencies you're starting with(which you would really need to
> ballpark to even pick the correct sensor)
>
> Hope this helps,
>
> Jim Akiba
>
> On Wed, Aug 6, 2008 at 12:06 AM, Mike Elliott <camping.elliott@gmail.com> wrote:
>> This is a question for the engineering geeks here.
>>
>> Say you were towing a little trailer behind your Vanagon. Say that the
>> trailer had a rudimentary suspension consisting only of leaf springs. Say
>> that this trailer also had tires, the pressure of which could be adjusted:
>> higher pressure results in a harsher ride, while lower pressure results in
>> a softer ride. Say you wanted to determine the optimum pressure of ride vs
>> tire squishiness but were unable to find a small boy to ride in that
>> trailer to report back about smoothness of ride v tire pressure while the
>> experiments were being conducted, so lacking that small boy, your thoughts
>> naturally turn to instrumentation. Okay, so say you had a laptop computer
>> (WinXP) which could ride in the passenger seat, and /three/ business days
>> in which to acquire the needed sensor (accelerometer?) as well as the
>> software to display the ride bounciness.
>>
>> Could it be done?
>>
>> --
>> Mike "Rocket J Squirrel" Elliott
>>
>
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