Lightweight 3d Drawing

[Guest Wragie]

Just wondering if anyone is interested in this to help them out (and me a bit)

 

I've been working on fixes for the frame, which is basically seeing what everyone

has done and seeing if I could add any of my own to help. During the process I

recreated the original LW chassis in Solidworks so I could see it more clearly.

This is not an exact duplication as I did not have enough dimensions to do that,

so it is close in some areas and out in others. What it does have is all of the parts

in the approximate locations. So what I am thinking is that I can save this out

to a Edrawings file that you can load into the free Solidworks viewer. At that point

you have a 3D image/model that you can spin tilt zoom explode to your hearts content

and see how things fit together.

 

I have hesitated offering to do this before as it isn't exactly representative. For instance

I have not done the various overlaps of sheet metal on the outer skins under the chassis.

So the deal is if you download and find something wrong let me know and I will correct

it and upload the new file. The edrawing file size btw is 100K so it doesn't take much

to grab.

 

Iso view of LW chassis not showing scuttle or tunnel cover (is modeled but not shown)

 

 

View of Boot with transparent skin showing fuel tank and some structure.

 

That's about all I can upload here to show but it should give you an idea of what you

can see or do.

 

Let me know and I'll post the drawing files and link to the viewer.

 

Dave

[Guest N1CK2B]

Thanks Dave, good job.

 

 

If anyone needs in a different format to view I can help with Autodesk (AutoCAD/Inventor/Mechanical) file formats.

[Guest mccaughd]

Hi Dave, N1ck2b and All,

 

My name is Damien and I live in Adelaide Australia.

 

My father in law has just purchased a lightweight. In Australia, the equivant of the SVA (as i understand) requires a beam and torsional test of the chassis. From my reading, the lightweight chassis is very flexible and is unlikely to comply with Aust Design Rules for the beam and torsional test.

 

What i would like to do is have a planned approach to adding stength to the chassis to make it comply with Aust design rules. An ideal way is to replicate the chassis is CAD and then apply force to it, see the results, apply changes in CAD and then test again. Gone is the old trial and error method in the shed.

 

I would appreciate it very much if i could grab a copy of the files related to the lightweight chassis as it would be a great headstart to the project.

 

BTW I have built myself a Locost with a Nissan SR20 with IRS and the lightweight will be one of a number of clubman type cars my father in law has constructed.

 

Regards

 

Damien

[Guest Wragie]

Welcome to the dark side!

 

If your Dad has the kit there at hand, then you have way more accurate information than I had to do this. With that in hand and cad I would start from there. The files I have are really only good for seeing what part goes where. They are not going to give enough accuracy for a FEA beaming test. For example I excluded all of the overlaps of the aluminium to make my life easier as Solidworks has a cow over those things. You would have to redraw the part to get it back to what/how RHE did originally. You still have to do the physical beaming test to get past the ADR.

 

All is not hopeless though, I've worked on a version of the original frame and managed to get it over 4000 NM without getting drastic so you should be able to increase it and get it passed. I've been puttering at pushing it over 6000 but haven't run anything yet. The problem areas are much like a steel tube 7 but here you have 3 "almost" connected bits. Nose, cockpit, and boot. Of those the rear suspension/boot area is the most lacking, the rest ties in nicely with side rails etc. The stock frame is sort of like wet spaghetti, it's all attached but sort of does what it wants to.

 

Willing to help out as much as I can but I don't think the files I have are what you will need. PM me if you want any details.

 

Cheers

 

Dave

[Guest mccaughd]

G'Day Dave,

 

Thanks for the quick response.

 

The car gets picked up in early July so unfortantetly we don't exactly know what we are dealing with until then.

 

It is very encouraging to hear that you got 4000nm without too much trouble. My Locost came in at about 3500nm in a tradtional steel chassis and well and truly satisified the beam and torsional test requirements for the Nissan 2l motor i used. There is a relationship between the chassis stength requirments and the engine size in Oz. I don't know the exact relationship except that the bigger/ more powerful the motor the stonger the chassis must be.

 

In Adelaide, we are fortunate to have a very strong clubman community and a couple of very supportive engineers so there is no doubt the car will be completed to meet registration requirements.

 

 

Cheers

 

Damien

[Guest Wragie]

Hi Damien

 

Collect the information from Grahams and ScotMac's posts and websites (and everyone else's).

They will give you a good clue on some of the fixes. Scot was reading this when I got here so

he knows whats coming (lots O questions).

 

I thought the ADR was 2000nm to pass on a under 2 or 3l engine. Have a little voice

saying they changed that in 06 or 05 so your mileage may vary. Really should be based

on weight not hp but not my rules. Planning on doing that here anyway (Canada) even

though there is no requirement. I'm not sure how stiff the RHE LW would be modified

so you may have a bit of work to get it over the limit. I've heard (not confirmed)

that it is only about 900nm which is pretty wimpy compared about 1400 for a Locost

frame.

 

Dave

[peter_m7uk]

Hi Dave,

 

Nice work, interesting approach! If you are using Solidworks to investigate the bending strength and torsional rigidity of the chassis,

that could give some really handy results. I was just thinking, though, looking at the bits of chassis that you've included in that Edrawing

pic, you seem to have missed out the entire tunnel top sheets, which do complete a box section running up the middle of the car. I think

the results with and without a complete tunnel could be quite different? Also, I would argue that the battery tray and even the scuttle are

important structural elements, as they again complete a box which is otherwise open on one side. The only other bits I would point at are

the eight thick aluminium square sections which are used to mount the suspension front and back. The front 4 in particular add an awful

lot of strength and rigidity at the front of the car when they are bonded, bolted and riveted into the surrounding area, so it isn't really

representative to miss them out. I don't know how easy it is to do, but I think if you added all of those elements to what you have now,

you would really see a big difference. This is just based on my "feel" for the design, but I think boxing off areas of chassis is very important

for a monocoque.

 

Hope your build is going well, anyway. Check out my site for progress on my own Lightweight. Hoping to have the engine running in August

 

Cheers,

Pete

[Guest Wragie]

Hi Pete

 

I did mention that those bits were modled but not shown ^^ up there. ;-]

 

The only thing I do not have in there is the diff. I didn't have enough dims

to recreate it. The rest is what you would see at the point where you start

bolting on the a-arms and dropping the engine in.

 

Dave