No insult intended! This idea spun so wildly out of control! What started as a mild curiosity -- whether I could use vibration analysis equipment to study a not-terribly-important seemed to take on a life of its own. I was not intending to put down your practical solution, instead, I was goofily spinning things toward absurdity. I just don't express myself as well as I wish I did and sometimes don't know when to put a sock into it. -- 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 >>>> >