Date: Fri, 8 Aug 2008 21:16:07 -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: <ac1f198b0808082053w7f7d2b8cn68977b348dafebe6@mail.gmail.com>
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Besides -- I'm a little anxious about this trip.
--
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 8:53 PM Jim Akiba wrote:
> Ah my mistake, I thought you actually wanted to get an answer as
> quickly/easily as possible ha... R Goldberg is about using creative
> unneeded steps to get the desired result, and make the whole process
> an interesting and fun distraction with the end result the punchline
> to the long setup. If anything is goldberg, this thread, the sensors,
> laptop, and software are it... you could have been done by now with a
> video camera.. hell even a piece of cardboard, elastics, and weighted
> magic maker will give you the peak to peak displacements of the
> trailer bounce! It's a *very* simple thing you're trying to find out,
> why complicate it? You don't need absolute data at all, only relative
> information is needed to reach the desired answer, and that's a piece
> of cake with very little... if it wasn't so dangerous indeed riding on
> it and reporting back would be even simpler. If you want an excuse to
> buy toys, that's different, but totally understandable as well... but
> at least acknowledge the fact that the simpler path to the solution is
> never by definition the goldberg one. You know the simplest thing to
> do would be to start the trip, adjust it on the road, and see if you
> can tell during the drive.. it might be obvious.. and if it isn't,
> it's not likely to matter all that much in any case so long as you
> aren't wildly out of range.
>
> Jim Akiba
>
> On Fri, Aug 8, 2008 at 7:02 PM, Mike Elliott <camping.elliott@gmail.com> wrote:
>> 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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