britishtrident
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| posted on 15/3/11 at 04:55 PM |
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quote:
Originally posted by Neville Jones
Mr.Britishtrident, STOP trying to be an engineer!!! You're talking a load of uninformed boll*cks regarding Davrians and polar moments.
Polar moment is the measure of how much weight is at the extremes. High polar moment has weight closer to the extremes than a LOW polar moment.
quote:
Perhaps you should start to behave less like an offensive fool.
Will you stop assuming anybody that that has served a proper apprenticeship doesn't have a degree as I told you already without spelling it
out too bluntly among my pile of diplomas and other bumf I have a very decent mechanical engineering degree from the days when universities used
actually have to subject their exams results to external verification and coursework couldn't be copied off the Internet (habit you clearly have
as I recognise the ( incorrect) information you have on Davrians was copied from a site I am familiar with. Like many of my generation I came up
the long route having deliberately chosen an apprenticeship as a seagoing engineer because it gave me the best possible grounding in widest spectrum
of engineering.
A lot of guys on this forum are very knowledgeable some of them have degrees (not always in engineering) some have post grads others
HNC/HND/OND/ONC or C&G others who get my respect don't have a single engineering qualification just a good logical brain and a retentive
memory, others have the real practical abilities I will never have such the gift and knowledge that allows them to run a perfect weld.
The practical lessons I learned in the practical side such as the proper way sweat on a starter ring on have been far more useful to me in life than
the fact I could once solve a control engineering problem by using Z space transforms or a vibration problem by the Eigen Value method.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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coyoteboy
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| posted on 15/3/11 at 06:17 PM |
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Don't worry guys, I am an engineer by quals too, I just like to hear experience from the ground as well as understand the theory and all
opinions and reasoning will be taken into account. I'm also aware that despite my experience in a few automotive areas, my knowledge in others
is lacking and it's good to hear both sides of any argument to help identify the correct answer, should there be one. Theory can tell you one
thing, experience on the ground tells you how much the theory applies to reality.
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Neville Jones
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| posted on 16/3/11 at 10:13 AM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by Neville Jones
Mr.Britishtrident, STOP trying to be an engineer!!! You're talking a load of uninformed boll*cks regarding Davrians and polar moments.
Polar moment is the measure of how much weight is at the extremes. High polar moment has weight closer to the extremes than a LOW polar moment.
quote:
Perhaps you should start to behave less like an offensive fool.
Will you stop assuming anybody that that has served a proper apprenticeship doesn't have a degree as I told you already without spelling it
out too bluntly among my pile of diplomas and other bumf I have a very decent mechanical engineering degree from the days when universities used
actually have to subject their exams results to external verification and coursework couldn't be copied off the Internet (habit you clearly have
as I recognise the ( incorrect) information you have on Davrians was copied from a site I am familiar with. Like many of my generation I came up
the long route having deliberately chosen an apprenticeship as a seagoing engineer because it gave me the best possible grounding in widest spectrum
of engineering.
A lot of guys on this forum are very knowledgeable some of them have degrees (not always in engineering) some have post grads others
HNC/HND/OND/ONC or C&G others who get my respect don't have a single engineering qualification just a good logical brain and a retentive
memory, others have the real practical abilities I will never have such the gift and knowledge that allows them to run a perfect weld.
The practical lessons I learned in the practical side such as the proper way sweat on a starter ring on have been far more useful to me in life than
the fact I could once solve a control engineering problem by using Z space transforms or a vibration problem by the Eigen Value method.
ALL BS!
You WERE an engineer on board ships. No degrees needed for that, other than the 'bits of paper' you got at the maritime college. Nothing
wrong in being a hands on grease monkey, and the practical experience can be invaluable.
You make many statements on here that show you have very scant(at best, to be generous) understanding of the basics of engineering theory, and anyone
who has been past second year of a degree course will see the howling mistakes you come out with. Those statements on polar moments are classic
examples. If you did a degree course, you spent a good deal of it in the pub, and bought the end certificate from Woolworths.
I,and my peers in my office, have to work with graduates who can't drill a hole and put a bolt in it, let alone spec the bolt size. We also work
alongside some of the best tradesmen/technicians in the world. A couple of us here have had the privileged upbringing to have very high levels of
practical skills , AND the education to back up the wheres and whyfores.
When engineering mechanics changes to say that high polar moments have the mass centralised, and low polar moments have the mass at the extremes, then
I might take you seriously. But hundreds of years of teaching isn't about to change.
Stick to what you know and are good at, and any comments to the contrary will be unneeded.
Cheers,
Nev.
And my comments on Davrians comes from hands on experience of the cars, nowhere near the internet! And some years before it existed! 
[Edited on 16/3/11 by Neville Jones]
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v8kid
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| posted on 16/3/11 at 02:08 PM |
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quote:
The practical lessons I learned in the practical side such as the proper way sweat on a starter ring on have been far more useful to me in life than
the fact I could once solve a control engineering problem by using Z space transforms or a vibration problem by the Eigen Value method.
Crikey! I've got a couple of engineering degrees and I struggled with Laplace transforms! Solving Z transforms deserves real respect. Now
I'm beginniong to feel inferior, I hate to think what have I missed in life by not knowing
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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Doug68
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| posted on 21/3/11 at 07:19 AM |
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Quoting from here
“Some people have made a bit of a big deal about it, but if we, HPD and Wirth Research didn’t push the envelope and make the car as light, as wide,
and as fast as the rules would allow, we wouldn’t be doing our job would we. “If we turned up with a car that was 5mm too narrow – we’d be leaving
performance on the table. The car has it’s tech inspection sticker in place and will be ready to roll in the moring. We’re really looking forward to
seeing how it performs.”
Doug. 1TG
Sports Car Builders WA
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v8kid
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| posted on 21/3/11 at 09:15 AM |
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They are talking about complying with regulations which limit the car dimensions and is not really relevent to the track/wheelbase relationship
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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Doug68
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| posted on 21/3/11 at 10:51 AM |
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quote:
Originally posted by v8kid
They are talking about complying with regulations which limit the car dimensions and is not really relevent to the track/wheelbase relationship
I'd say it shows the opposite LMP cars can be up to 2m wide as per the regs. Clearly they see benefit in using all of that and are prepared to
push it to the last mm to get the wheels as far apart as possible.
I think the wheel base discussion cames after that, which is more to do with packaging etc.
If you look at modern LMP cars they can vary quite a lot in wheel base but they're all near as dam it 2m wide. For example the data below is a
radom sampling from http://www.mulsannescorner.com you can see a 210mm difference in wheel base and a 30mm difference in the overall width. Given
that the body of the car won't be made wider than required to cover the tyres and discounting the changeing tyre sizes over the years (some of
this years cars are running fronts wider then the rears I believe) its clear that the wheels are being put as far apart as possible
Bentley Speed 8 from 2003
Width: 1990 mm
Wheelbase: 2740 mm
Peugeot 908 from 2010
Width: 2000 mm
Height: 1030 mm
Wheelbase: 2950 mm
Lola LMP1 from 2009
Length: 4630 mm
Width: 1999 mm
Height: 1029 mm
Wheelbase: 2890 mm
Courage C65 LMP2 from 2005
Length: 4650 mm
Width: 1970 mm
Wheelbase: 2790 mm
Front overhang: 860 mm
Rear overhang: 1010 mm
Front track: 1750 mm
Rear track: 1600 mm
Toyota GT1 from 1999Length: 4840 mm
Width: 2000 mm
Height: 1125 mm
Wheelbase: 2850 mm
Front Overhang: 1000 mm
Rear Overhang: 990 mm
Track Front: 1600 mm
Track Rear: 1644 mm
[Edited on 21/3/11 by Doug68]
Doug. 1TG
Sports Car Builders WA
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v8kid
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| posted on 21/3/11 at 12:43 PM |
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Thanks for the clarification Doug I know nothing whatsoever about LMP cars.
My point is in general designers design to the regulations for a particular class and it can be misleading to draw general conclusions from this.
It may be that there are some other considerations in the regs that force this circumstance but in view of my ignorance on LMP I'm happy to
defer to you if you are quite sure there aren't.
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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Doug68
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| posted on 22/3/11 at 01:32 AM |
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quote:
Originally posted by v8kid
My point is in general designers design to the regulations for a particular class and it can be misleading to draw general conclusions from this.
Too true.
Doug. 1TG
Sports Car Builders WA
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coyoteboy
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| posted on 22/3/11 at 12:04 PM |
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Certainly can be misleading I know. The question is "is it indicative". If, for any formula (with a similar target use), the designer
doesn't push the max of the allowable envelope then you can assume it's not that important. If they all tend to push it as wide as
possible it's a good indication that in that use it's a positive.
A 2m wide car would allow plenty of bay space for....a pair of litre bike engines. Plenty of wishbone length to maintain susp geom through travel.
Lots of positives. The only thing I can see as a neg is added drag and possibly tougher on twisties.
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cheapracer
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| posted on 22/3/11 at 12:15 PM |
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quote:
Originally posted by Doug68
If you look at modern LMP cars they can vary quite a lot in wheel base but they're all near as dam it 2m wide.
[Edited on 21/3/11 by Doug68]
For the record Doug most LMP and F1 cars etc's wheelbases are more dependent on aerodynamics and not mechanical grip thats why they are all up
around the 120" mark.
It's coming....
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v8kid
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| posted on 22/3/11 at 12:33 PM |
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Something else that just came to mind is how are you going to get it to the racetrack? My front track is 1536mm with rear track of 1498mm and with
8" tyres on front and 11" on rear I can just squeeze it in a standard Brian James trailer. Be a bu66er if you built it and could not get
it on the trailer 
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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cheapracer
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| posted on 22/3/11 at 12:34 PM |
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quote:
Originally posted by britishtrident
Actually the Stratos was infamous for twitchy handling -- it was very fast due power to weight ratio, and great traction which came from weight
distribution and long travel suspension but the short wheelbase and low polar moment meant it was only a useful tool when in the hands of the very
best drivers at the top of their game.
At the end of the day a car will only go so fast around a corner regardless of who's driving it and since the Stratos did well everywhere on
every conceivable road surface (include the East Africa Safari for example) over a long period of time one would have to say it handled rather well
overall.
The power to weight ratio was not that spectacular and quite comparable to others at the time but it was a purpose built rally car with weight over
the driving wheels with room for massive tyres and as you mentioned, long travel for rough stuff.
It is well documented that Markuu Alen and others drove the Stratos by choice over other competitive options verifying that "nervous" or
not, they weren't scary.
It's coming....
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cheapracer
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| posted on 22/3/11 at 12:40 PM |
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quote:
Originally posted by coyoteboy
A 2m wide car would allow plenty of bay space for....a pair of litre bike engines. Plenty of wishbone length to maintain susp geom through travel.
Lots of positives. The only thing I can see as a neg is added drag and possibly tougher on twisties.
You do not want to own a 2 meter wide car daily or when you get to twisties and "plenty of wishbone length" is poo for "maintaining
geometry thru travel" and pretty much from your view is exactly the opposite of what you need.
It's coming....
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v8kid
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| posted on 22/3/11 at 02:04 PM |
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quote:
Originally posted by cheapracer
"plenty of wishbone length" is poo for "maintaining geometry thru travel" and pretty much from your view is exactly the
opposite of what you need.
I thought that was exactly what we need the only reason we don't have it is due to packaging reasons. Can you expand on that please
cheapracer?
Every time I run a SLARK spreadsheet the only way to get reasonable camber recovery without large track variations is to lengthen the swing arm how
are you doing it with short arms?
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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coyoteboy
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| posted on 22/3/11 at 02:39 PM |
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quote:
You do not want to own a 2 meter wide car daily or when you get to twisties and "plenty of wishbone length" is poo for
"maintaining geometry thru travel" and pretty much from your view is exactly the opposite of what you need.
Now you have lost me mate, longer wishbones = possibility of smaller rates of change of camber during bump (more space to select wishbone length to
suit). Small package cars suffer from having short wishbones which drastically alter the geom as it moves through the travel.
2m wide car isn't THAT wide, it's only a foot wider than my current normal car.
[Edited on 22/3/11 by coyoteboy]
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Doug68
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| posted on 23/3/11 at 11:06 AM |
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I think that whether or not a 2m wide car is apropriate or not depends upon where you live and where you like to drive.
Here in Australia the standard Falcon or Commodore is ~1900mm wide at the body and ~2.1m accorss the mirrors, going to the USA C6 Corvettes are a
little wider than that, but these examples would be considered monster cars in the UK.
[Edited on 23/3/11 by Doug68]
Doug. 1TG
Sports Car Builders WA
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coyoteboy
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| posted on 24/3/11 at 01:16 AM |
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Monsters, yep. Nothing quite as mad looking as a car thats massively flat and wide. There are quite a few 1900ish wide (not track) crs in the uk
though - 7 series BMWs for example. Not disproportionately wide?
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liam.mccaffrey
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| posted on 25/3/11 at 09:15 AM |
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just to add, it looks like my car will be around 1850 to 1900mm overall width
Build Blog
Build Photo Album
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Neville Jones
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| posted on 25/3/11 at 12:06 PM |
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A 70's/80's 911 turbo body is 1800 wide across the rear arches, for a comparison.
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cheapracer
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| posted on 30/3/11 at 05:50 PM |
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quote:
Originally posted by v8kid
quote:
Originally posted by cheapracer
"plenty of wishbone length" is poo for "maintaining geometry thru travel" and pretty much from your view is exactly the
opposite of what you need.
I thought that was exactly what we need the only reason we don't have it is due to packaging reasons. Can you expand on that please
cheapracer?
Every time I run a SLARK spreadsheet the only way to get reasonable camber recovery without large track variations is to lengthen the swing arm how
are you doing it with short arms?
Cheers!
By "track variations" I presume you mean lateral scrub where the contact patch of the tyre moves sideways in distance from the vehicles
centerline?
Firstly modern radials are designed to accept a mild amount of lateral scrub without any consequence and a high profile tyre can even need a chunk to
take up the 'sidewall slack' and get to a stabile slip angle before the lateral weight shift of the car itself takes effect - one reason
production car racing use around 40 + psi.
One of the key determining factors of lateral scrub is the height of the outer lower BJ, the higher it is the more lateral scrub you will get all
things being equal - thats a simple lever equation. Most standard uprights have a high BJ for LCA ground clearance first, handling second, one
advantage to making your own uprights. before aerodynamics took over everything in motor racing you will notice that lower BJ's are outside of
the wheels and nearly scraping the ground in older race cars.
Long arms are for F1 due to aerodynamics and not related to whats best for road cars. Only generally speaking and the way most lay them out, longer
arms will not provide enough camber gain and incorrectly continue the negative camber gain they have in the upper travel regions (ever heard of the
Atom's snap oversteer)?
Again and generally speaking the way they are laid out (Locost for example), shorter arms provide correct negative camber gain initially and then
later positive, yes positive not negative, camber gain in the upper regions of travel (nearing full bump).
Keeping this as simple as possible, when you turn into a corner the car will roll a certain amount, you want camber gain to keep the tyre square to
the road - I'm sure you all follow that easy enough. Now what you don't want is when you are in this nice steady state and the car hits a
bump or undulation and the suspension compresses further (the car barely increases it's roll), of course you want that tyre to stay square to
the road, you do not at that moment for the tyre to increase it's camber further decreasing tyre contact patch.
When you have shorter arms you can design the lower ams arc to start decreasing the neg camber gain immediately after you achieve your ideal initial
neg camber gain, the arc starts to draw the lower BJ towards the center of the car - the longer the arms the less chance you have to achieve this and
the closer you will be to a linear gain and a small one at that.
Try to find a 'real' car such as Ferrari, Lambo, Porsche, etc. all noted for brilliant handling that has long Aarms and don't state
packaging as a reason for them either, Enzo's weren't designed to go shopping in. Note how short they all are - not stupidly short of
course, there's a balance to everything.
Now who here knows better than Ferrari, Lambo or Porsche?
Ever seen an Ultima's suspension Aarms?
Ferrari Enzo?
[Edited on 30/3/11 by cheapracer]
It's coming....
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Neville Jones
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| posted on 31/3/11 at 10:35 AM |
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That diatribe above is so full of misquotes and misconceptions, it is difficult to know where to start.
Cheapracer, you're the fella who tried to tell us that some sort of LM car is designed with a bucket load of trail, and no caster, right?
Then you put up pics of a front corner, supposedly of a V8 supercar, which was supposed to show that even the supertaxis had trolly trail, but the pic
was so fuzzy as to be useless.
You've yet to post proper pics of either of the above, despite being asked.
I've been very close to both disciplines quite recently, and can tell everyone here, with a good degree of confidence and surety, that neither
of the above cars is designed anywhere close to what was being said.
These common misconceptions, are mainly due to forums with statements like yours.
1. Wishbones should be as long as possible. This is constrained by packaging and parts being used. The reason is to minimise lateral changes in bump
and droop.
2,. The long lower bones in top end racecars are for very good reason, and not aero. See above.
3. The supercars you mention, are as they are, due to design compromises being taken, and not ideal geometry. Look at the length of F40 bones compared
to those of ferrari's 30 years ago and more.(Have a look at the construction. More 'locost' like than you might expect!)
4. Ultima are not the epitome of what suspension design is all about. More to do with 60's design thinking, and Staniforth. (who was a
journalist, not an engineer!)
A close family member is about to start a year in the chassis department of one of the top F1 teams, let's see what he comes back with. They
also do engineering and build work for other teams and disciplines, which I was surprised to find out.
Cheers,
Nev.
[Edited on 31/3/11 by Neville Jones]
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cheapracer
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| posted on 31/3/11 at 02:48 PM |
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quote:
Originally posted by Neville Jones
That diatribe above is so full of misquotes and misconceptions, it is difficult to know where to start.
Cheers,
Nev.
[Edited on 31/3/11 by Neville Jones]
Nev? Is that you Nev? LMAO.
Why don't you just start at the beginning Nev, tear it apart one sentence at a time, show me your "stuff".
Misquotes would indicate that I have quoted somebody else, that would be incorrect, I do all my own work there Nev.
I offer actual explainations but you offer dismissasl, can you or can't you offer any actual statements on the workings of a suspension system?
Can you back up what you write when you do (if you do)? I am quite happy too.
By the way Nev, that "non existent" LMP2 car, the one runs around zero caster and about 65mm of trail won LeMans class last year, won 4
rounds of 6 (2 DNF's) and was on LMP2 pole every race, it is by far the fastest car out there in LMP2 and beats most LMP1 cars - HTH.
Now start your next post with something like "this is why a long Aarm suspension is better ...." and cut the personal poo - so get to it,
put up some counters and cut with the mouth.
It's coming....
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Neville Jones
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| posted on 31/3/11 at 03:28 PM |
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What do you want, diagrams and explanations in simple words? My explanations are all over this forum, and plain enough to me and a few others.
'cut with the mouth', now that's a bit ripe coming from someone who's just posted that load of smart mouth rubbish.
You have yet to post the pics of that LM car, showing the 'trail' clearly.
Do just that, close ups which can be verified, and you may live in peace.
My statements come from (nearly) everyday hands on experience.
Cheers,
Nev.
[Edited on 31/3/11 by Neville Jones]
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cheapracer
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| posted on 31/3/11 at 03:46 PM |
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Neville, why are longer Aarms better than what is similar to what say Ferrari use on their unrestricted designed Enzo or even a common but well proven
Locost/Caterham/Westfield?
What do you think are the main problems with their general length compared to say an Atom's F1'ish style length?
Possibly a moderator could encourage Neville to answer without trolling?
[Edited on 31/3/11 by cheapracer]
It's coming....
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