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Author Topic: Trojans take on engineering  (Read 17411 times)

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SPEC

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Re: Trojans take on engineering
« Reply #45 on: April 29, 2009, 11:44:19 PM »
 ;D
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trojan

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Re: Trojans take on engineering
« Reply #46 on: April 30, 2009, 02:42:27 AM »
OK, after being beaten over the head with a  dictionary (thanks Oz) I'll rephrase:
Draughtsman vs Engineer.
it seems a lot of draughtsmen call themselves engineers....
And like I said, the fact that Doug drew it up for them is cool in itself.

Newtonian Physics.
F = ma
P = mv
S = ut + 1/2at^2
http://en.wikipedia.org/wiki/Vector_sum#Vector_addition_and_subtraction
http://en.wikipedia.org/wiki/Strength_of_materials
http://en.wikipedia.org/wiki/Trigonometry
http://en.wikipedia.org/wiki/Structural_analysis
etc......
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Offline Boostinjdm

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Re: Trojans take on engineering
« Reply #47 on: April 30, 2009, 03:27:56 AM »
You mean Draftsman vs. Engineer?
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Offline fabr

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Re: Trojans take on engineering
« Reply #48 on: April 30, 2009, 06:43:00 AM »
Let's take trojan to task here. Use as an example a front lower a-arm with no rake. Seems pretty simple and I'm sure that many of us have built them (notice I didn't say design or engineer them). Starting at the frame , detail for us where you would start with engineering them. Lets assume they are 20 inches long. Shock mounts to a arm 15" from frame pivots. ASsume the arms are symetrical and the mounts are spaced 12" apart.Car will weigh 1200#'s with a 60/40 weight distribution.Car front track is 72". Objective is to allow the arm to survive a 10mph impact to the outer heim from any direction with an immovable object/tree. What else is needed? ANyway,trojan ,engineer it.
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"There can be no divided allegiance here.  Any man who says he is an American,
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artie on edge

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Re: Trojans take on engineering
« Reply #49 on: April 30, 2009, 07:04:46 AM »
Quote from: Masterfabr on April 30, 2009, 06:43:00 AM
Let's take trojan to task here. Use as an example a front lower a-arm with no rake. Seems pretty simple and I'm sure that many of us have built them (notice I didn't say design or engineer them). Starting at the frame , detail for us where you would start with engineering them. Lets assume they are 20 inches long. Shock mounts to a arm 15" from frame pivots. ASsume the arms are symetrical and the mounts are spaced 12" apart.Car will weigh 1200#'s with a 60/40 weight distribution.Car front track is 72". Objective is to allow the arm to survive a 10mph impact to the outer heim from any direction with an immovable object/tree. What else is needed? ANyway,trojan ,engineer it.

I say build it outta 25 mm (oops sorry 1") solid bar, try it and see if it bends. If it doesnt, up the size by 200 percent to allow a safety factor...

Seriosuly Trojan, this challenge is beneath you mate..Id ignore it.... if I wasnt such a smartarse ....
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trojan

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Re: Trojans take on engineering
« Reply #50 on: April 30, 2009, 09:36:38 AM »
Everyone in the real world knows that science and engineering are done in metric ::)
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Offline fabr

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Re: Trojans take on engineering
« Reply #51 on: April 30, 2009, 11:33:04 AM »
It's not a challenge.It is asking for an explanation of the process that wouild be involved.Trojan posted up a bunch of stuff that is relevant and I assume he knows how to use it or it is irrelevant. The point is that there is no exact science in engineering anything.That is why 10 engineers will come up with 15 different"correct" answers to the same question.IMO my "challenge" makes that perfectly clear.TOO MANY variables to be able to engineer it in the first place. Engineer has it right IMO with WAG.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

trojan

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Re: Trojans take on engineering
« Reply #52 on: April 30, 2009, 12:58:16 PM »
I can take it if I'm wrong.
If it was "Wild ass guesses" analysis software couldn't do it's job?
It's not easy, that's my point.
Simply, so you get to ignore things like friction and gravity, hell include them it's your dime, you would define everything required and convert from your "medi-evil" system to metric ;D
Then:
A dash of: http://en.wikipedia.org/wiki/Polar_moment_of_inertia
A sprinkling of: http://en.wikipedia.org/wiki/Area_moment_of_inertia
A scoop of: http://en.wikipedia.org/wiki/Section_modulus
A pinch of: http://en.wikipedia.org/wiki/Elastic_modulus
A touch of: http://en.wikipedia.org/wiki/Yield_(engineering)
Then find yourself a table of yeild strengths for the material you want to use and apply what you've got to to that. eg: http://www.davesport.com/cgi-bin/davesport/specs.html

Munch!
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Offline fabr

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Re: Trojans take on engineering
« Reply #53 on: April 30, 2009, 01:52:47 PM »
Heheheheheeee,I know that and yet it still requires a lot of hunches and best guesses. That's my point. I'm not saying it CAN'T be done just that it will alll be based on WAG.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

trojan

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Re: Trojans take on engineering
« Reply #54 on: April 30, 2009, 04:45:15 PM »
nah no WAG. in your example, hitting the immovable object dead on will transfer the most energy, and will cause the buggy to rotate about an axis. knowing the total mass and length of the "lever" and the speed, we can calculate the force applied. Calculating the overall yield strength required of the triangle is matched to the triangulated yield strength of the arm constructed of the minimum sized available tube.... giving the answer you asked for.... essentially like  Finite Element Analysis software does.... or are you saying FEA software just guesses wildly?
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Ozpilot

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Re: Trojans take on engineering
« Reply #55 on: April 30, 2009, 06:24:59 PM »
Quote from: trojan on April 30, 2009, 02:42:27 AM
OK, after being beaten over the head with a  dictionary (thanks Oz)

Sorry Trojan, I was biting my tounge till the "invitation" turned up - I just figure "design" means stacks of things and I thought Doug's use of that word was fair.  To use an example, I said on this board recently something about "designing" my al trailer.  When I "designed" the trailer I carried out calculations with data being specific corner weights of the buggies and material weights etc in formulas to work out the loading involved and resulting moments to position the axle but the rest of the design (material sizes etc) was from experience - so when I say "design" it doesn't always mean calculations.

BTW, I have a long standing gripe about draftsmen calling themselves engineers.  Draftsmen have valuable skills (mainly in using software these days from what I know).  However, if you can't sign off then you're not an engineer (in my book) so I understand the point you were making. 
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trojan

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Re: Trojans take on engineering
« Reply #56 on: April 30, 2009, 07:10:34 PM »
Mate, don't be sorry! I'm glad to  be shown where I'm mistaken, misled or wrong, even though the latter never happens ;D
And I'd like to think I'm man enough to take it on the chin ;)

Now, being merely contraire (hi Fab) on the other hand, is down right annoying :P
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Offline fabr

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Re: Trojans take on engineering
« Reply #57 on: April 30, 2009, 07:43:43 PM »
Yes,(trojan) being contrary just for the fun of it is annoying. ;D ;D ;D ;D Now  tell mewhere I'm wrong in what I said about engineering being the RESULT of trial and error and then engineering slowly came into being with the lessons learned from that very trial and error.Secondly where am I wrong in thinking that much of what is "engineered" is just a Wild Ass Guess at best that can be demonstrated with math tobe correct but based upon that very WAG.
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"

trojan

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Re: Trojans take on engineering
« Reply #58 on: April 30, 2009, 07:44:28 PM »
 :t
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Offline fabr

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Re: Trojans take on engineering
« Reply #59 on: April 30, 2009, 07:48:41 PM »
Aw,c'mon,mate! You know I'm right! ;D
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"
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