Lotus Elan

"Monocoque"

PostPost by: elj221c » Tue Nov 22, 2011 1:22 pm

Mine is ISBN 0-947981-95-0. Published 1995.

I just had a look and there is one for sale at Abebooks. £145! :shock:

I thought that the £29.50 I paid back then was steep.........
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PostPost by: garyeanderson » Tue Nov 22, 2011 1:46 pm

No clue as usual, my copy is also 1989 so I have a lovely Sprint leading a pack. Oh Well. My thoughts may be wrong again but it seems that the topic has been productive.

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PostPost by: CBUEB1771 » Tue Nov 22, 2011 3:17 pm

ardee_selby wrote:I always understood that strength was also derived from the energy needed to break the grip between fibres & resin i.e. fibre pull-out from the matrix material which, apart from fibre lengths, was also a function of the resin composition.


Richard,
I did over simplify. The toughness of the matrix is vital to keeping the fibers oriented in the correct direction. Matrix toughness is also important when a composite structure is loaded in ways that the fiber orientation may not be optimal for, i.e. collision impact v. normal suspension loads.
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PostPost by: GrUmPyBoDgEr » Tue Nov 22, 2011 4:21 pm

elj221c wrote:Mine is ISBN 0-947981-95-0. Published 1995.

I just had a look and there is one for sale at Abebooks. £145! :shock:

I thought that the £29.50 I paid back then was steep.........


Aha, that probably accounts for mine having a different page 127; the book has a total of 168 pages & your later edition it would seem has grown to include additional information.

Suppose that makes my ol' 1st Edition worthless? :roll:

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PostPost by: GrUmPyBoDgEr » Tue Nov 22, 2011 4:26 pm

CBUEB1771 wrote:
ardee_selby wrote:I always understood that strength was also derived from the energy needed to break the grip between fibres & resin i.e. fibre pull-out from the matrix material which, apart from fibre lengths, was also a function of the resin composition.


Richard,
I did over simplify. The toughness of the matrix is vital to keeping the fibers oriented in the correct direction. Matrix toughness is also important when a composite structure is loaded in ways that the fiber orientation may not be optimal for, i.e. collision impact v. normal suspension loads.


Laying up fibres, be they glass, carbon, kevlar etc., in the X, Y & Z Axis is
"the Holy Grail" that is still being sought.
One day, maybe :roll:

Cheers
John
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PostPost by: elj221c » Tue Nov 22, 2011 4:47 pm

GrUmPyBoDgEr wrote:Suppose that makes my ol' 1st Edition worthless? :roll:


John, I would think not. First editions and all that.

Just for the record, my '95 copy has 256 pages. Does your edition have the +2 in it? My one does. I guess you also don't have the Ron Hickman notes.

Gary has shown that the early cars had a ribbed floor. I guess that was because the frameless design needed extra stiffness there.
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PostPost by: ardee_selby » Tue Nov 22, 2011 5:48 pm

GrUmPyBoDgEr wrote: Laying up fibres, be they glass, carbon, kevlar etc., in the X, Y & Z Axis is "the Holy Grail" that is still being sought. One day, maybe :roll: Cheers
John


"etc"?

Hemp, eco-wool, sisal...http://www.ruleworks.co.uk/carguide/lotus-eco-elise.asp

Straw! http://www.design-technology.org/comp2.htm

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PostPost by: CBUEB1771 » Tue Nov 22, 2011 6:38 pm

GrUmPyBoDgEr wrote:Laying up fibres, be they glass, carbon, kevlar etc., in the X, Y & Z Axis is
"the Holy Grail" that is still being sought.


John,
I agree that current solutions are far from optimal but there has been a fair amount of work done with Z-axis reinforcement of thin composite panels to increase resistance to delamination. Thin aluminum pins have been used:
https://dspace.lib.cranfield.ac.uk/handle/1826/107
I used to work for a company doing much of this development.
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PostPost by: GrUmPyBoDgEr » Tue Nov 22, 2011 7:00 pm

CBUEB1771 wrote:
GrUmPyBoDgEr wrote:Laying up fibres, be they glass, carbon, kevlar etc., in the X, Y & Z Axis is
"the Holy Grail" that is still being sought.


John,
I agree that current solutions are far from optimal but there has been a fair amount of work done with Z-axis reinforcement of thin composite panels to increase resistance to delamination. Thin aluminum pins have been used:
https://dspace.lib.cranfield.ac.uk/handle/1826/107
I used to work for a company doing much of this development.


I recall the problems that Rolls Royce ran into over 30 years ago in their attempt to manufacture fan blades for their big by-pass engines.
Those very complex shapes would be easily manufactured with composite materials if the Z axis problems could have been resolved.

Not wishing to sound (too) flippant as I appreciate that you are talking in nano type engineering, but using alloy rivets to hold laminate layers together sounds like a manufacturing method that Brunel would have appreciated :D

Cheers
John
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PostPost by: cabc26b » Wed Nov 23, 2011 3:14 pm

Gary,

here is a drawing of the torque box off a Marcos GT that used a wood monocoque - they don't need to be huge .
Btw for the Marcos the sub-frame was attached to the foot boxes( forward most part) . stiffness was reported to have been greater than what we have with the elan.
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PostPost by: dodo_z » Tue Nov 27, 2012 11:40 am

Yesterday evening I was looking for some information about parts and the different sources in my Robinshaw and Ross "Authentic Lotus Elan and Plus 2" copy.

There is a illustration on page 127 which isn't described. This might be a drawing from the time when it was discussed if the Elan should get a chassis or not.
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PostPost by: TurbineHeli » Tue Nov 27, 2012 2:53 pm

A very interesting discussion here.
I have an early S1 26/0505.
Perhaps this has already been discussed but is seems to me that the plywood instrument panel would provide some degree of torsional stiffness to the S1 body. Even more so if it spans the full width of the body. This may partly explain why the polyurethane finish cracks.

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PostPost by: dodo_z » Tue Nov 27, 2012 3:28 pm

TurbineHeli wrote:...seems to me that the plywood instrument panel would provide some degree of torsional stiffness to the S1 body. Even more so if it spans the full width of the body. This may partly explain why the polyurethane finish cracks.


This would be an explanation why the dashboard is also showed in the mentioned drawing.
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PostPost by: GrUmPyBoDgEr » Tue Nov 27, 2012 3:53 pm

Hi guys; I got a message that this thread has woken up.

Yes the dashboard has a very important function in fixing the sides of the body & the scuttle to the backbone of the body & chassis.
For that reason large fasteners & load spreading bushes pushed in to the plywood are used to take the loads that may be transferred through the dashboard.
The cracks that so often appear in the dashboard varnish may be caused by these loads but my money is on the dashboard not sitting flat onto the body bosses (bobbins) & twisting moments being induced during assembly; almost impossible to avoid, I think.

Cheers
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PostPost by: elj221c » Tue Nov 27, 2012 6:21 pm

dodo_z

From page 4 of this thread, my interpretation of the parts.

elj221c wrote:I have read and reread this thread and I can't find any reference to the Robinshaw and Ross book wherein, in my edition at least, there is a drawing showing clearly how the Elan might have been without the backbone frame.
It is on page 127 under the heading; The Two-Seater Elan. Some further notes. (Written by Ron H)
I assume that Gary has not seen this as his idea is based around a Spyder type frame. I suspect a few other contributors to this thread haven't seen it either. Interestingly the diagram has question marks pertaining to the suspension mounting reinforcing frame at the rear and what looks like some kind of outrigger to the battery box mouldings both sides and being attached to a tunnel reinforcing frame. Or maybe the thought was that the whole tunnel reinforcing fabrication might be superfluous? There are nine separate sections but the dashboard is bolted to the front bulkhead of the tunnel member.
1 & 2. The sill reinforcing latice.
3. Front turrets and cross member.
4. Rear turrets and diff cross member
5. Tunnel member formed of a bottom and three bulkheads.
6. Cross brace under the engine.
7. Cross brace to presumably hold the headlight actuators.
*. This number is not used although the S1 style dash is highlighted as one of the components so I assume it is number 8.
9?Rear suspension mounts. Not sure why the question mark as I would have thought that this bit would be required.
I would like to have scanned the drawing but it is copyright to Motor Racing Publications Ltd. Essentially all the components look similar the those that we recognise except the are now all joined by more sheet steel, the tunnel reinforcement being the exception as we know that the other three sides have been added. I'm not sure about 7 as I do not have pop up lights. Is there a cross brace at that point on 'proper' Elans?

GrUmPyBoDgEr wrote:Yes the dashboard has a very important function in fixing the sides of the body & the scuttle to the backbone of the body & chassis.
For that reason large fasteners & load spreading bushes pushed in to the plywood are used to take the loads that may be transferred through the dashboard.
Cheers
John


John, (back here! :) )

I replaced the dash on the S2 with a home made job but I don't remember any load spreading bushes on the original. Was that just on the S1?
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