Benonymous
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| posted on 16/12/07 at 05:57 AM |
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Neo7 Project
Hi All.
I have been lurking for a while and learning heaps of good stuff. My intention is to build a BEC project and as you see I have opted to make it
front-mid-engined as I think that the irritation of reverse is best solved with a Quaife reversing box and not a big mess of gears and electric motor
and other Heath Robinson stuff. Id be interested in your opinions of the initial design. Click on images for a larger size.
I'm planning to construct the chassis with a steel called Hi Lite made here in Australia. The larger tubes will be 50x2mm and the smaller
diameter will be 35x1.5mm.
Thanks to information off the forum I'll also be looking for a Freelander diff and driveshafts for the rear. All suspension will be pushrod
coilovers and unequal length 'A' arms.
[Edited on 16/12/07 by Benonymous]
[Edited on 17/12/07 by Benonymous]
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Doug68
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| posted on 16/12/07 at 07:12 AM |
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Make sure you can buy Hi-Lite where you are in WA I never managed to find a small volume supply of the stuff.
I resorted to the more common GR350 material.
Doug. 1TG
Sports Car Builders WA
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Benonymous
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| posted on 16/12/07 at 09:22 AM |
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Hi Lite
I am in NSW, right next to Port Kembla steel works. I reckon I can get Hi Lite but if not, I'll settle for mild steel in similar dimensions.
BTW Doug, I've looked at your website and I really like what you're doing  I won't be starting this project for real until next
year as my shed is filled up with unfinished sea kayaks ! Don't you have a onesteel outlet in WA?
[Edited on 16/12/07 by Benonymous]
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Puk
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| posted on 16/12/07 at 09:57 AM |
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Hi Nice concept - great name too! Looking at your frame sketch the area between the front suspension pickup looks a little open. Have you considered
how you will pass the loads into the chassis yet?
It is this front "box" that often seems to be the fist area to be strengthened when people set out to make Locost chassis stiffer. The
catering-van (another great name!) CSR introduced a load of stiffeingin this area.
http://en.wikipedia.org/wiki/Caterham_CSR
 
Rescued attachment Caterham_CSR_Suspension.JPG
Before you judge a guy, walk a mile in his shoes. Then when you judge him, you're a mile a way and you've nicked his shoes.
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Doug68
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| posted on 16/12/07 at 12:14 PM |
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We have One Steel over here but they wont bother stocking the stuff unless you want a rail car full it seems.
The difference between the materials is actually not as big as it looks, I spoke to a tech guy at one steel and apparently as even though the Hi-Lite
has a UTS of 450mpa it develops an equal amount of strain at lower loadings to GR350, so probably the only benefit you will see to it is in horror
situations.
I had been trying to get the stress / strain graphs out of one steel but gave up when getting the stuff was obviously going to be too hard.
Thanks for looking at the website, I sometimes wonder if anyone does.
BTW amongst all the other crap in getting a car registered in Aus, you'll have to pass a 4kn per degree torsion test. So you might want to
think of doing some stress analysis on the design before you get cutting metal.
A book locost wont do 4kn and neither will many other UK kit cars (not sure about the Atom) and there is no such requirement in the UK. So just be
careful where inspiration is drawn from.
I like the design if it were me though I'd put the engine in the back and either forget about reverse of use one of these:
They're double the price of the reversing unit though.
Doug. 1TG
Sports Car Builders WA
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Benonymous
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| posted on 16/12/07 at 06:06 PM |
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Steel
Thanks for the feedback. Puk I'm going to use a laser cut sheetmetal part in the front of the chassis, less hassle than a load of small tubes.
I hear what you're saying with regards to the steel Doug. I'm not married to the idea of using the Hi Lite. Actually the whole idea
started off as a mid-rear but I thought if it's going to be a modern Lotus Seven style car it really should be mid-front. I wonder how many
production cars would pass 4Kn too. You just have to wonder at our bureaucracy here in Aus. What are they trying to achieve with these enthusiastic
targets? maybe it's just to discourage us.
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ettore bugatti
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| posted on 17/12/07 at 07:11 PM |
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Looks nice.
Do you have some dimensions? (track, wheelbase)
I would make the passenger entry a bit larger though.
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Benonymous
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| posted on 17/12/07 at 10:32 PM |
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Passenger entry
Yeah, that's been bugging me I think I need another 100mm for the passenger compartment opening front to rear. This is the second draft of the
chassis and there will probably be others. The basics will stay pretty much the same though.
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Benonymous
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| posted on 19/12/07 at 04:08 AM |
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V2 Chassis
This is actually the third draft of the chassis. I really should post a pic of the one where one of the cross members on the top of the frame went
through the occupants!
Anyway, the passenger opening is larger now and I've put in a draft of the bulkhead for the suspension in the front. An identical one would be
in the back. I had a look at the Caterham CS chassis and they've put a couple of pyramid structures in the front, very stiff! There is a bunch
more triangulation to go into my effort, and a transmission/propshaft tunnel. Comments are welcome
BTW Track and wheelbase dimensions are shown on the reference dimensions in the images
[Edited on 19/12/07 by Benonymous]
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ettore bugatti
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| posted on 19/12/07 at 06:50 PM |
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Your track is very wide. So big lateral G's is no problem
Mind the propshaft, though.
You will need in this config a split one. Since you not connecting @ the crank, but at the transmission.
Still you are at the right direction.
Keep the progress!
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Benonymous
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| posted on 19/12/07 at 10:32 PM |
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Yeah, I figured on a split propshaft with the quaife reversing box acting as a centre bearing. If it ends up putting the reversing lever in a
difficult place I'll just remote it.
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ettore bugatti
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| posted on 20/12/07 at 12:15 PM |
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Hmm, that's not a bad idea.
I think I will use the split prop shaft in my design as well.
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Benonymous
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| posted on 14/1/08 at 12:09 AM |
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A little progress, big mods.
A little progress. I have dealt with a couple of issues. The main one was that the rear wheels lacked sufficient clearance from the vertical tube at
the rear and the curved top tube. I thought about it for ages and decided to extend the wheelbase 200mm to move the diff centre back. I also
ditched the curved tubes at the top and bottom rear and went with straight ones. Much simpler. I have also added a truss that goes in to tie the rear
suspension subframe to the top rear cross tube.
Comments and suggestions are welcome :-)
[Edited on 14/1/08 by Benonymous]
[Edited on 14/1/08 by Benonymous]
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Alan B
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| posted on 14/1/08 at 01:30 AM |
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quote:
Originally posted by Benonymous
......you see I have opted to make it front-mid-engined.......
Or as most of us traditionalists would call it..."front-engined"...
Seriously though, despite my hatred of marketing BS inspired terminology, it's developing into a really nice project.
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Puk
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| posted on 14/1/08 at 07:51 AM |
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quote:
Originally posted by Benonymous...I have also added a truss that goes in to tie the rear suspension subframe to the top rear cross
tube...
Hi B'
That new truss is triangulated in the plan (XZ plane) but doesn't look to be in plane parrallel to the seat back (XY). Did you consider tying
them in like this:
 
Neo7 - truss comment GIF
http://www.locostbuilders.co.uk/upload/TrussDesign.gif
Sorry adding images seems to be a bit hit or miss!
[Edited on 14/1/08 by Puk]
[Edited on 14/1/08 by Puk]
[Edited on 14/1/08 by Puk] 3rd time got it!!
[Edited on 14/1/08 by Puk]
Before you judge a guy, walk a mile in his shoes. Then when you judge him, you're a mile a way and you've nicked his shoes.
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Benonymous
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| posted on 14/1/08 at 10:18 AM |
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I hadn't considered that....
I hadn't considered that Puk. It looks good in the plane you've drawn in but that leaves a quadrilateral between the tubes you've
added.
Its all speculative at this stage however so I'll make a version like you've suggested and include it in the testing later on.
I based this choice on a local builder who has been keeping a build diary on his 'Godiva' project. It was surprising to see that in a
similar area of his car that this truss assembly is superior to a pair of crossing (X shaped) tubes in the same area.
As he points out. If the angle of the crossed tubes is too acute, it's stiffer to have a truss, closer to 45 degrees in the corners.
This whole thing is a great learning exercise for me and the joy of using SW is the fact that I can load the chassis and get a really good idea of the
torsional strength before laying down a single weld.
I was looking at Dennises car (DP Cars) a couple of days ago and I was very surprised to see how little triangulation he had included in his chassis.
He has used stressed aluminum skins for stiffening.
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Puk
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| posted on 14/1/08 at 10:36 AM |
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Hi B'
I'm wary of the long term strength of stressed skin steel frame, even though early 7s did use that technique. I've got no direct
experience but two issues appear to me:
1 if bonding - difficult to be certain that you have a structurally sound joint.
2 if you discount bonded joints you are left with mechanical methods - rivets. Rivet holes experience high local stress which leads to strain and a
loosening of the joint. Perhaps wrapping the skin around the tube before riveting would give a better stress distribution - difficult to model
though??
That said I'm designing chassis that will use composite aluminium panels, and am hoping to find some mechanism for creating a reliable bonded
joint. Jaguar are mass-producing riv-bonded aluminium chassis so it must be achievable.
Have you considered approaching Dennis to ask him how he mitigated against these risks?
Cheers,
Puk
Before you judge a guy, walk a mile in his shoes. Then when you judge him, you're a mile a way and you've nicked his shoes.
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Puk
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| posted on 14/1/08 at 12:04 PM |
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B- just reread your response and you pointed out that my solution wasn't triangulated in the horizontal plane. Guilty as charged.
Thinking further though, wouldn't the horizontal loads be introduced by the reactions at the inboard ends of the suspension wishbones? If so
horizontal triangulation in the plane between the inboard suspension pickups might allow you to get away without a diagonal brace higher in the frame.
Maybe count the diff as a stressed component tying the inboard suspension pickups together. FEA or long hand truss analysis would help untangle that
lot.
Cheers,
Puk
Before you judge a guy, walk a mile in his shoes. Then when you judge him, you're a mile a way and you've nicked his shoes.
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Benonymous
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| posted on 14/1/08 at 10:27 PM |
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Stressed skin.
Hi Puk. I'm actually not proposing to use any stressed skin in my chassis. I used Dennis as an example just because I found it interesting
that he chose that route.
I agree with you on the stressed skin issues. I built a locally produced Seven replica many years ago and when I put the floor skin in I used
bathroom silicone as an adhesive. Unfortunately I had to remove the skin and the silicone was unbelievably tenacious. Got it off but it was
buggered.
I think I could go bananas putting triangles into the chassis and then having to redesign around inconvenient items like shock absorbers and steering
racks and the like 
While the basic layout will not change, I feel there may be more versions of this as I go on. More versions from scratch. It's fun to do and
with the FEA in SW I'll be able to give it all a good twist!
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Puk
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| posted on 10/4/08 at 09:20 AM |
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Kindered spirit:
Linky to LocostUSA
Before you judge a guy, walk a mile in his shoes. Then when you judge him, you're a mile a way and you've nicked his shoes.
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