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Author: Subject: Chassis Weight
orton1966

posted on 28/12/10 at 09:01 AM Reply With Quote
Chassis Weight

Iím currently finalising my midi design and drawing it up in solidworks. One of the aspects thatís always concerned me about some exo-midiís is relatively poor triangulations so Iím currently trying to satisfy myself whilst still keeping the Ďexoí look.
Just out of interest I looked at the projected weight, I think Iím heading for about 75kg for the chassis does this sound about right?


[Edited on 28/12/10 by orton1966]

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JoelP

posted on 28/12/10 at 09:53 AM Reply With Quote
that bit at the front will be tricky to make, to say the least





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russbost

posted on 28/12/10 at 11:11 AM Reply With Quote
75Kg is exactly the weight of the Furore chassis, the Furore is quite a large car, but obviously tandem seating saves some weight so shorter & wider I'd say you're about spot on - that front end with all the tubes coming together at a single point is identical to MNR's lmp car & they seem to manage it without a problem!





I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours. http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

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matt_gsxr

posted on 28/12/10 at 11:13 AM Reply With Quote
Square tube striker chassis including braced rollbar comes in at 62kg.
Striker is considered to be pretty light (in an oldskool way)

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russbost

posted on 28/12/10 at 04:55 PM Reply With Quote
Just an observation, the chassis as shown has no bracing to the lower engine bay & would be very weak - particularly if you were mounting suspension to those tubes!





I no longer run Furore Products or Furore Cars Ltd, but would still highly recommend them for Acewell dashes, projector headlights, dominator headlights, indicators, mirrors etc, best prices in the UK! Take a look at http://www.furoreproducts.co.uk/ or find more parts on Ebay, user names furoreltd & furoreproducts, discounts available for LCB users.
Don't forget Stainless Steel Braided brake hoses, made to your exact requirements in any of around 16 colours. http://shop.ebay.co.uk/furoreproducts/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

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loggyboy

posted on 28/12/10 at 05:24 PM Reply With Quote
It also seems to be missing the curved tube on the Drivers side going from the bottom of the roll car to the rear edge of the cube.
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orton1966

posted on 28/12/10 at 06:23 PM Reply With Quote
Yes still missing a few tubes

quote:
Originally posted by loggyboy
It also seems to be missing the curved tube on the Drivers side going from the bottom of the roll car to the rear edge of the cube.


Yes still missing a few tubes; at the front will be small diameter diagonal tubes in the rectangle space between the upper and lower wishbone mounts, there is a stressed one-piece floor (sandwich composite), engine will be a stressed component and at the rear a stressed diffuser/under-tray.

Also, as spotted, not all tubes are drawn in, especially at the rear. The front tube arrangement, as noted, was something also on a couple of LMP style cars and does really help triangulate the front, so worth the effort

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MikeR

posted on 28/12/10 at 06:42 PM Reply With Quote
If possible make the floor to go on the floor and around the sides to the lower chassis rails (making a large 'u' shape). This will add a lot of strenght but i've no idea how you'd do it practically using sandwich composite.
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orton1966

posted on 29/12/10 at 06:52 AM Reply With Quote
Fortunately....

quote:
Originally posted by MikeR
If possible make the floor to go on the floor and around the sides to the lower chassis rails (making a large 'u' shape). This will add a lot of strenght but i've no idea how you'd do it practically using sandwich composite.


This is really my area of most expertise, composites have been my trade for 20+ years, so I have a couple of ideas

The most likely way will be to make a mould, first by making a buck actually on the finished chassis. In its simplest form this will mean Iíll just turn the chassis upside down fill the flat sections with flat board, carve the rounded section in foam, skin, fill and apply a spray primmer-filller to finish.

The mould will be a simple one piece GRP moulding, if I use vinylester resin this is temperature resistant enough to use low-temp pre-preg (60 deg. Cure) if I chose to go that route for the finished part but Iíll probably wet-lay and vacuum bag with regular epoxy

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indykid

posted on 29/12/10 at 11:32 AM Reply With Quote
your nearside lower rail seems to curve in 2 planes. is that odd solidworks perspective or the actual shape of the spline? i'd try make it single radius/single plane bends to aid fabrication if i were you. istr nitram had enough trouble getting anyone to ring roll his rails with a change in radius

are you using weldments in solidworks? if not, the tutorial's thorough and easy to follow. it's good to give you an idea of the final shape of tubes and will tidy up a few of your overlaps. also useful if you want your tubes laser profiling dependent on budget

i know the spider brace at the front may be a design feature, but have you considered making it primarily an X to tie the rearmost front wishbone uprights together and then working back to the node in the x?

not sure why you've gone so high with it (pedal box clearance?) but surely it'd be stiffer if at least one x was working in plane. it'd help stop the front box lozenging too, though i imagine it's imperceptible stiffness gains.

finally, can we have some more ortho views of it please? i like stuff like this. one of my christmas jobs is to start reworking our formula student spaceframe for the electric car.

tom






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orton1966

posted on 31/12/10 at 07:01 AM Reply With Quote
Thanks for the input. Iím pretty new to solid works, the model is built with weldments but I havenít played with trimming tube ends etc. so Iíll give the tutorial a go.

The top and bottom main-tubes both feature two radius but each of these is only rolled in one dimension, although the plane they sit on in the model differ (forward and rearward of the roll-hoop) giving the corkscrew effect. Iím relatively happy with the top one but at certain angles the bottom one doesnít quite flow right. I think increasing the angle will improve things effectively this means lowering the rear end of the chassis, I might try putting up a before and after pic so people can judge the result.

There are a few things that arenít finally dimensioned yet, some are just down to making final decisions, cockpit width/length. Some hinges on other modelling, front and rear suspension and others are about playing until it looks right. The thought about the height of that area of tube joints is that this can also support the Ďbonnet/front panelí (for want of a better word) but it might also become a central shock mounting for the pushrod suspension so its height and position might change a little with that


quote:
Originally posted by indykid
your nearside lower rail seems to curve in 2 planes. is that odd solidworks perspective or the actual shape of the spline? i'd try make it single radius/single plane bends to aid fabrication if i were you. istr nitram had enough trouble getting anyone to ring roll his rails with a change in radius

are you using weldments in solidworks? if not, the tutorial's thorough and easy to follow. it's good to give you an idea of the final shape of tubes and will tidy up a few of your overlaps. also useful if you want your tubes laser profiling dependent on budget

i know the spider brace at the front may be a design feature, but have you considered making it primarily an X to tie the rearmost front wishbone uprights together and then working back to the node in the x?

not sure why you've gone so high with it (pedal box clearance?) but surely it'd be stiffer if at least one x was working in plane. it'd help stop the front box lozenging too, though i imagine it's imperceptible stiffness gains.

finally, can we have some more ortho views of it please? i like stuff like this. one of my christmas jobs is to start reworking our formula student spaceframe for the electric car.

tom

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cheapracer
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posted on 3/1/11 at 11:33 AM Reply With Quote
With floor, all braces and brackets you won't beat 100kgs.





It's coming....

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Doug68

posted on 3/1/11 at 10:41 PM Reply With Quote
Hope you have the suspension - damper pickups sorted as without this it's it kinda putting the cart before the horse.
Looks nice though, the point at which you have 7 tubes coming together will need sorting, either done away with somehow or a fixture put in there for the tubes to weld onto, as that situation will be a PITA to do.

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posted on 8/1/11 at 09:17 PM Reply With Quote
I weighed mine today with suspension, axles, brakes but no calipers and 3 wheels bolted on and got 150kgs.

Quite happy, am on target for my hoped for 500kgs with 2 litre engine.





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