That disassembled ECU photo is great.
Thanks!
William
Printable View
That disassembled ECU photo is great.
Thanks!
William
I have not yet seen another front beam. Everyone seems to be sticking with wishbones there.Quote:
Originally Posted by Pete Marsh
We are building a 4 corner spring car this year. The change is due to an overall concept decision and tight manufacturing timeline, we are already machining parts for this year.
Thought I would share the 2015 UQR beam. Triangulated 4 link with roll centre and antisquat adjustment. Whole assembly including all links and brand new tyres (exactly what you see here besides driveshafts) weighs in at 20kg. Main tube is 2.5x0.065" 4130.
Would like to thank Kev and Z for their excellent input into this thread. There are a few pages from ~20-23 that are absolutely gold if you're interested in 4 link design.
Thanks for sharing that Mitchell, looks really tidy!
Couple of queries:
-your upper trailing arms appear to be non-nodal. Problem?
-does this configuration have adequate lateral restraint or am I missing something?
Good spotting Jay. The upper link on the chassis is not triangulated. The attached picture shows more clearly. To put it in perspective the whole length of that tube is ~150mm. It is primarily due to packaging and the goal to have a certain amount of antisquat adjustment without changing the length of the link.
Lateral restraint is fine. The links are as far apart as packaging would allow on the beam with the uppers nearly inside the wheel and the lowers with ~5mm of clearance to the sump. This puts them nearly perpendicular in top view.
That makes more sense, cheers
Totally unrelated, but wow that car is small!
Yeah they mostly look great before subjecting them to the nose cone atrocity haha
Erik,
Back to page 22 there was a discussion about Inertial Forces.
I think nothing can describe what I've learnt and wanted to discuss better than this video about Inertial Frame Of Reference
https://www.youtube.com/watch?v=aRDOqiqBUQY
Better to watch it starting from 13:00.
Ahmad,
I liked the first few minutes of the video where the first presenter showed real commitment to his belief that his "frame of reference" was the right one. Or, at least, that his frame was just as good as the second presenter's. Even though, on a practical level, it obviously wasn't!Quote:
Back to page 22 there was a discussion about Inertial Forces.
...
https://www.youtube.com/watch?v=aRDOqiqBUQY
Unfortunately, the rest of the lesson repeats the same old ideological claptrap that claims "Inertial forces are fictitious".
This nonsense starts with the ASSUMPTION, at ~10:15 of the video, that "... the "Law of Inertia" [states] An object moves with a constant velocity unless an UNBALANCED force acts on it". (<- My emphasis.)
Then, when strange motions are observed in accelerating frames that seem to contradict their assumed version of the Law of Inertia, they argue "... our belief in the Law of Inertia is so strong that when we see [this strange motion] we think there is a force causing it, so we make up a fiction that there is a force, and ... call this a fictitious force..." (<- at ~16:25+).
In other words, they start with a flawed assumption, and then when the facts get in the way they call these observably real facts "a fiction". But, as all small boys who fall out of their billy-carts as they try to take the corner at the bottom of the hill too sharply know, the (fictitious?!) "centrifugal" forces are very, very, real!
Claiming that Inertial forces are "UNreal", "fictitious", etc., just because they contradict a faulty assumption, does not make them so.
Much more that can be said, but I will keep it to the following two points.
~o0o~
Newton explained all this much better and more reasonably in his "... Principia...". Quotes below are taken from Motte's English translation.
In Axiom 1 (or Assumption/Law...1), Newton uses the words "... forces impressed upon [the body]", rather than the modern corruption used in the video of "...unbalanced force". The video version (and other comments in the video) make it clear that they consider there is a net (or "unbalanced") EXTERNAL force acting on the accelerating body, but NO equal and opposite ("balancing") INTERNAL "Inertial reaction force".
By contrast, Newton makes it very clear in his Definition III (right at the front of book!) that all massive bodies have a "... 'vis insita' or innate force of matter, ... [that may] be called inertia (vis inertiae) or force of inactivity..." (<- my emboldening). Furthermore, Definition IV makes clear that "An impressed force is an action exerted upon a body...", and Newton stresses the difference between these (external) "impressed" forces and the (internal) "Inertial" forces.
The reason for the above corruption of Newton's version of Mechanics is that early 20th century science had no good explanation for how "Inertial" forces work, so they simply got rid of them at the "axiomatic" stage (ie. at the ~10:15 quote from video).
This was also done because in the late 1800s the "Relativists" (a sort of scientific/religous cult founded by Ernst Mach) were trying to abolish any notion of preferred reference frames, such as the Absolute Space that Newton discussed in the Scholium at the end of his Definitions. It was also partly because of the speed-of-light experiments that were being done at that time, that the Relativists wanted all reference frames to be equally valid (a bit like modern teachers preaching that "all opinions are equally valid"). So anything that depended on "the rest frame of the universe", such as "Inertial" forces, had to go.
Of course, the recently conceived Higgs Field may give a reasonable explanation (?) of Inertial forces, with the HF acting as the universe's "rest frame", or N's Absolute Space. But before "HF=Inertia=real" can be accepted and widely taught, the science teachers will have to admit they have been peddling bulldust for a hundred years. So we might have to wait quite some time for an update (or apology?).
~o0o~
Modern science teaches that in any NON-accelerating frame it is perfectly acceptable for all the usually acknowledged "real" forces acting on a body to sum to zero, or be "balanced".
For example, a book sitting on a table has a downward gravitational force acting on it, and an exactly "balancing" (ie. zero-sum) upward E-M force acting on it. Both these forces are the result of the relative POSITIONS of the various stuff. Position of book-CG and Earth-CG for the gravity forces, position of lower-book-atoms and upper-table-atoms for the E-M forces.
Similarly, "Magnetic" forces are the result of charged particles moving at a relative VELOCITY to other stuff, and these forces can also be in perfect "balance" with other real forces. In a looser sense, a winged-racecar travelling along a racetrack has VELOCITY dependant aero-downforce that can also be in perfect "balance" with the upward road-to-wheel E-M/atomic forces. And there are many other examples of bodies in various states of "motion" that have perfectly "balanced" systems of forces acting on them.
So the big question is: Why should ACCELERATING bodies be the ONLY CASES where there MUST BE an "unbalanced" system of forces in action?
Is it not simpler to always have all the forces acting on the body as "balanced"?
(That is, you determine the balanced system of forces necessary for a body's given position, velocity, and acceleration relative to other stuff around it, and thus predict the subsequent behaviour of the body. Too easy?)
All that is needed here is to acknowledge the reality of Inertial forces. (Which is something all small boys already know! :))
Well, ... also needed is that apology from the Scientific Establishment (sort of like the Vatican) for peddling such nonsense. Could take some time...
Z