82 replies to this topic

[dead_eye]

Afternoon all, ive got a few idiot questions for you! ive been trying not to ask them but im no materials engineer and everywere else i look for info on this baffles me!

Im just about to start building the spaceframe chassis for my new track, and ive poured everything ive got into it (its even a true spaceframe-feels good to be 5'6 and 10st ) But now im coming to the building point im looking at other options i didnt really consider before, probably due to cold feet and trying to delay it all :

so first off, has anyone heard of or seen a titanium spaceframe/ rollcage before? Im contemplating building the front and rear subframes from ti but there seems to be a distinct lack of it use in this area. It maybe because the teams with the money for use cf monocoques instead or ive missed something in its stats that makes none of its grades suitable for the job?? like i said im no materials engineer.

Secondly, ive got a supply through work of various carbon fiber honey comb panels with various different materials but mainly ally honeycombs. Ive seen a few top end cars now using these for their bulkhead panels and floor panels due to the superior stiffness off them. How ever all the materials i seem to find on them are sae style papers etc and to someone whos never come across them before quite baffling! So if anyone could fill me in on the details it would be much appreciated. i.e are they a design in material like a pre peg component with the fibers the right way etc or is it like and ally sheet that can just be bonded on, that sort of thing really as there more than a bit alien to me.

thirdly does anyone know of a reliable way to bond steel tubes to carbon fiber tubes? im looking at removing some of the smaller non critical triangulation pieces in chassis and replacing them with carbon tubing to help bring the weight down. However other than a mechanicall bracket (like those used in bolt in roll cages) i cant find a reliable way of doing it? perhaps a stressed sheet over the whole section would resolve the problem better?

Ohhhh why couldnt i just be happy with what i had lol now im all confused again!

The cars a closed top single seater btw est finished weight 690kg with a 49:51 f:r weight split.
Its subject to no regs and ideally the front and rear subframes will be removable and replaceable as 1 unit to facilitate complete fresh suspension/ engine changes etc as my crazy learning curve needs to test its theories on.
thanks, harry

[Goran Malmberg]

I may not come up with a good answer to this complex question, just a short note worth mentioning.
The material strength discussion comes up now and then. Ok, we should not overlook the importance of selecting the right material, but to put things in the right proportions let me describe a situation.
I made a torsion test of my own car, that showed not to be to glorious, some 7000 fp/dgr. After X bracing the weak rear area of the car, the number raised to 15500 fp/dgr. Now, the tubing was simple extruded aluminium! It appear by far more important to put the triangulation in the right possition than selecting the right material concerning torsional stiffness. This tubings was also light, to say the least.
Regards
Goran

[cheapracer]

There is a radical new material that has just come on the market that you may be interested in although it requires an extreme bonding technique.

I think its called "mild steel tube" although I could be wrong (try Google).

The new technique I beleive is called "welded triangulation" - again sorry if its the wrong term as its such a new process.

Not much is known about it at this time but further investigation at these websites may prove fruitful....

http://sports.racer.net/index1.html

http://www.apexspeed...isplay.php?f=70

http://www.stohr.com/

http://www.phoenixracecars.com/

[jeremy durward]

i agree with cheap racer, mild steel is the easiest and possibly the better option all round.

as for bonding carbon tube insted of using metal for triangulation i'd have thought a flat panel of carbon would be the way to go there, look up west race cars, they use a paneled space frame in mild steel and carbon.

i also think there might be a problem bonding carbon directly to metal... or so i'm told by a boating friend of mine. apparently there is a reaction through electrolosis which corodes the metal.

[Stefan_VTi]

You could start by reading this thread about rollcage tubing:

http://forums.autosp...&threadid=75278

[Fat Boy]

As the crowd has already recommended, go with steel. In terms of fabrication, I tend to like 4130 better than mild steel just because the mills seem to make it a little more cleanly and so it's less of a problem getting a clean weld. I've had some mild steel tubing that has a bunch of crap in it and no matter how well you clean it, the welds come out suspect. Having said that, a good DOM 1018 steel will easily do anything you need it to do.

Racecar chassis' are generally built to a certain level of strain as opposed to a certain level of stress. If a chassis is so flexible (i.e. strains are so high) that the stresses become an issue, then you need to start over. From that perspective alone, 4130 is generally overkill....until you crash.

[dead_eye]

evening all, thanks for the advice

cheap racer- if you extend your search you will find info on various other metallic and composite substances that can be joined through various other means have differing qualities including density and stiffness.
Ive built succesfull spaceframe cars before but this is going to be the test bed for a few ideas ive got and is looking to be fairly special already (think bentley speed 8 in miniature). My point is having put so much effort into designing everything if by using some other more exotic materials and paying a bit more i can improve the chassis then i will. After all why put up with a car that takes 5 minutes to get into for that extra bit of strength when asking a few questions about other materials could considerably increase the chassis capabilities?

TBH because the subframes will be removable im mainly concerned about the main tub and making the bulkheads, floor and roof as strong and light as possible. any changes i need to make to the subframes i can do at a later date when i know a bit more about the use of these materials and im more confident in their inclusion.

P.s mild steel may be cheap and easy but when youve got a cheap supply of t45 it would just be silly

[J. Edlund]

In the past it was not uncommon to use for example aluminum for roll cages and space frame chassis. But in recent years I think safety regulations have gotten harder in this respect while the teams with big budgets have moved to the use of monocoque carbon fibre chassis with "integral roll cage".

For instance Ti-6Al-4V offer a strength of around 900 MPa with a specific gravity of 4.5 resulting in a specific strength of about 200 MPa. 4130 steel offers a strength of 600-1200 MPa depending on heat treatment. With a specific gravity of 7.85 that results in a specific strength of 75-150 MPa, not that much behind titanium but still I think it's uncommon to heat treat it after welding to higher strengths. In any case, both materials offers a similar specific stiffness of around 26 GPa, so building a chassi from titanium has no stiffness advantage and you are probably more likely to have stiffness issues before you have strength issues.

Given the increased material cost of Ti-6Al-4V compared to the small increase in specific strength (which you don't have much use of) I think that it's generally not a wise investment to use titanium. But titanium can probably be a good choice if it needs to be mated to carbon fibre, due to the low CTE of titanium and galvanic corrosion issues when bonding carbon fibre to aluminum or steel. On the other hand, with the increased cost of titanium it is perhaps better to switch to a aluminum/aluminum monocoque with CNC machined aluminum bulkheads instead.

Mild steel is cheaper than 4130 and offer a similar specific stiffness, but the higher strength has advantages. Especially when it comes to safety.

[Fat Boy]

Originally posted by J. Edlund
In any case, both materials offers a similar specific stiffness of around 26 GPa, so building a chassi from titanium has no stiffness advantage and you are probably more likely to have stiffness issues before you have strength issues.

Given the increased material cost of Ti-6Al-4V compared to the small increase in specific strength (which you don't have much use of) I think that it's generally not a wise investment to use titanium.

Bingo, Bango, Boom!

Strangely enough, Aluminum and Magnesium also have similar specific stiffnesses to steel and ti. It's just one of those little jokes God plays on us.

[cheapracer]

BSA used a Ti frame for Jeff Smith for a year in motocross in the 60's and couldnt stop the thing constantly cracking/breaking. Yes tech may have changed but sorry, its the only example I know of.

This is really great reading..... http://www.motorcycl...eID=2807&Page=1


As with Fat Boy, since your not bound by rules, alloy frame would look great and do the job as well intergrated with Ti crosstubes etc. make it a boltable deal (using Ti bolts as well) and really wow them :-)

Honeycomb alloy has a history in racing, I'm sure someone here can point you in that direction or search for classic race car restorers maybe? Maybe someone at Lotus can inform you as to the chemical supplier for the glues? I have a mate who's ex-Lotus, I'll ask him if the gluing was before his time or not.

From your first post you sounded like a newbie, excuse my humour ;)

[cheapracer]

Originally posted by Fat Boy
I've had some mild steel tubing that has a bunch of crap in it and no matter how well you clean it, the welds come out suspect.

.

ex China or India no doubt. I sometimes bend pieces of 25mm x 2mm square that get to 30 degrees or a tight radius on 25mm tube and "SNAP"

The ChMoly 4130 is a very American thing I think, not the big go, at least in my circles, in Australia but then again Australian mild steel tube is pretty darn good.

[NRoshier]

Look on the FSAE forum and also the sports 2000 forms plus others, see below:
http://www.apexspeed...orums/index.php
http://dsrforum.yuku.com/
http://fsae.com/grou...a=Y&s=763607348

The Lotus adhesive is an elevated temp cure epoxy. There are plenty of structural acrylics and epoxies that can do the job e.g Hysol 120, but research what is in your area.

[dead_eye]

many thanks guys, just read my reply to you cheap racer it had been a bad day yesterday hope it didnt come across to sarcy lol

I did contemplate aluminium especially with the cheaper costs to, although off the top of my head i believe while ally is lighter due to its weakness over steel id end up needing to use nearly twice as much of it? and then some more to make up for its low youngs modulous?
carbon fibers looking the most tempting at min with its low weight and ym of 130-150 with an even resin/ carbon mix. Trouble is i like to know what going on in my car and i wouldnt know were to start calculating the stresses through multiple layers of carbon and alinging grains with forces etc so i may end up with something worse than i start with!


the hunt for the perfect material continues:D

[NRoshier]

There is no perfect material, everything has it's benefits and downsides. One thing to keep in mind is that a lot of very clever people have been down this road before and it is unlikely that you will 'invent' a new process etc. Re alloy, I am writing an article on the 917/30 ATM, which uses a gas welded spaceframe...and it has a shrader valve on the chassis so that they could pressurise it to check for cracks...
Folded honeycomb panel construction is perhaps something you should investigate more and also look at the Daytona Prototypes for a different method of using the material.

[dead_eye]

oh definately but coming from a pure engineering background im playing with a lot of newish versions of old ideas and a lot of old ideas that were abandoned as they wernt practical at the time. tbh i get just as much enjoyment from learning about say how forces dissipate in a new material as i do from hitting an apex right. And lets face it the mistakes are normally more interesting than getting it right! which is why i was to determined to make a fully triangulated space frame work etc things most designers cant do due to practicality. For instance the engine going in this chassis to start with is supercharged and turbocharged with infinetly variable inlet AND variable exhaust manifolds, hydraulic valve operation (i.e no cams) and the intake is fed through a vortex cooler to give an inlet charge temp of -10 deg at the plenum inlet.

Every one of those systems amongs all the other was designed from bare sheet of paper from the theory up and taken damn near every penny, drop of blood and tear i have lol but the joy i get from seeing it run cant be explained. I guess deep down i just need a challenge to keep my mind working and it makes sense to match it up with my love for driving.
for instance at the moment every chassis node or load node is supported by at least 3 chassis members (triangular triangulation if you like:D) but i cant resist sitting here doodling trying to make it work support them all with 4 nodes members instead. incidentaly ive come up with a design i call the spider hub that looks very promising at the early stages but a nightmare to build!

I might do the main tubs strucutral members in steel for my own safety and do everything else in carbon fiber tube at least that way if the car dies i dont. theres virtually no bending loads in the frame with it being a space frame just the nominall flex the cf should be ok but if i remember correctly i need to be carefull with tension aswell as cf has ultra low elongation factor? Im going to a local company tomorow that do parts for BAR honda to see what they have to say and learn the various way of joining composites and types etc

[Fat Boy]

So, I see you're taking the K.I.S.S. approach for your first car.

[cheapracer]

F1 cars are nor built for any loads other than what they do, they aren't a good place to start for an all round track day car.

Notice the incidents on the weekend and the immediate destruction of components, noticeably A-arms, the moment non designed loads struck them.

Bill Sherwoods web page has a slightly different pyramid thingy spaceframe featured, not sure if for strength or for something mystic, Bills trying to keep himself fresh or something ;)

[Bill Sherwood]

Originally posted by cheapracer
Bill Sherwoods web page has a slightly different pyramid thingy spaceframe featured, not sure if for strength or for something mystic, Bills trying to keep himself fresh or something ;)

Smartarse.

It's a Mallock Mk31, and they have a fairly stiff chassis.



You can use a few different materials, you just have to make sure all the loads going straight down the tubes - that way they can be light and the whole thing stiff enough.

[mariner]

A few observations, I am not qualified enough to give answers.

In principle stressed skin monocoques are stiffer/lighter than spaceframes BUT their overall efficiency depends a lot on how well you feed in the point loads like spring and engine mounts. On planes the need to pressurize makes stressed skin well nigh essential but they are also easier to make efficient because there are only 4-7 point loads ( three undercarraige struts plus 1-4 engines).

Cars have many more point loads , up to 6 per suspension corner, two for the rack and 3- 4 for the engine. So up to 28 point loads all of a reversing cycle and subject to high frequency vibration as well as force loads.I think the success of a monocoque depends a lot on how efficiently you get these loads into the thinnest possible skin. If you think through the transition down the load path from a 10mm spring bolt to a 1.5 mm or less skin over a large area that is where the design skill probably lies.. A single seater is maybe easier as the lower cross section dictates a thicker skin than possible on a wide sports car tub, also on sports cars you usually have to "bend" the load path out around the front wheels to the outer car edge whereas single seaters are a straight run.

Lots of times several point loads are combined ( the famous Lotus top spring mount/top link mount and roll bar fixing trhough one bolt). Then a good stong bulkhead , machined if you can afford it, makes sense as you "stitch" the thin skin all around the long bulkhead diameter.

So I suspect it is not only easier,cheaper and quicker to fabricate a spaceframe but it is easier to design it right so at the lower budget/engineering resource levels spaceframes do very well. Minimum weight limits help them too.

One other comment on fixing carbon fibre panels to spaceframes. As Henry Rolls said " ultimately all materials are elastic". So if you fit a stiff panel which starts out unstressed to a tube frame which takes the intial stress load most of the panel to tube joining will take little of this stress because there is a differential movement acros the panel edge as the tube stretches.The old teaching aid on this was four sticks in a rectangle , a sheet of rubber and lots of nails joining them. The nail holes elongated around the nails at different rates all round the frame edge! Eventually all the joint is stressed but by then you have the very chassis flexing you dont want. So CF panels may be very good for impact protection but less effective in boosting pure stiffness.

[Bill Sherwood]

Originally posted by mariner
Minimum weight limits help them too.

Not really - you still build the car absolutely as light as possible with whatever you can use/afford/get, then ballast it up to the minimum weight with the mass also where you want it.
It can easily end up being more expensive.

[NRoshier]

When I contacted multimatic re their daytona prototype chassis I was told that the ali honeycomb panels added approx 10% to the stiffness of the space frame.
A carbon panel will have adhesive attaching it to the tube and a mechanical fastener to stop peel, so panel fixture via rivets etc is not usually an issue. A carbon panel is unlikely to be as good in an accident as an alloy panel of the same dimensions as the composite is not usually reckoned to be good in the secondary impact. Carbon and steel will also have a galvanic corrosion issue.

[Fat Boy]

Originally posted by NRoshier
When I contacted multimatic re their daytona prototype chassis I was told that the ali honeycomb panels added approx 10% to the stiffness of the space frame.

But, the rest of the car was made with al dente pasta, so..........

[cheapracer]

Originally posted by Bill Sherwood


Not really - you still build the car absolutely as light as possible with whatever you can use/afford/get, then ballast it up to the minimum weight with the mass also where you want it.
It can easily end up being more expensive.

Bang on the mark for the new F1000 category in the States. The 1000lb min weight entrants are $50,000 700lb racers with ballast. So much for the original idea of a steel tube frame with min weight to keep cost down.

http://www.stohr.com/

http://www.phoenixracecars.com/

[dead_eye]

fatboy- its my first FULL chassis design/build, that doesnt mean i havent got experience in other areas ;)

Bill- have you got any more pics of that chassis? looks very interesting!

[Canuck]

I'm wholly unqualified to be in this discussion but...if money isn't a consideration and doing something way outside the boundaries is, then this might be the stuff you're looking for. It's an all-metal MMC (no ceramics) that will break the bank and it's not legal in any racing series that I'm aware of. In addition,there are health risks associated with it however having said that, I work with it's variants on a daily basis and it's not hard to devise adequate safe guards though I doubt you could find anyone to weld it for you. It seems to me the FIA banned the use of the material specifically over the health concerns but that seems like a bit of a red-herring to me (though perhaps brake systems should not have been the place to use it).

[mariner]

No offence to Phoenix racing or any other constructors but if the organisers of an "amateur" series are letting people build 700 lb cars then put in 300lb of ballast then I think they are deficient in their scrutineering process. Not only is it clearly going to drive up cost for no purpose to anybody but it is potentially MORE dangerous than no minimum limit because the designers have to bulid a car at 700lb with 100lb strength instead of doing a 700lb car with 700lb strength.

[dead_eye]

canuck half my valve trains berrylium i didnt delve into the depths of its though the work was done by an ex cosworth machinist. sounds fun i believe its ubbber stiff foor its weight about 400ym in its pure form?
haha il smoke anything with a kick to it
;)
Although cost isnt a limiting factor i.e if it will do the job il get it im no millionaire but this will get some serious consideration!
out of interes anyone know how youd go about welding an mmx with the different melt temps etc wouldnt it just turn into a hot mess?

[McGuire]

Originally posted by mariner
No offence to Phoenix racing or any other constructors but if the organisers of an "amateur" series are letting people build 700 lb cars then put in 300lb of ballast then I think they are deficient in their scrutineering process. Not only is it clearly going to drive up cost for no purpose to anybody but it is potentially MORE dangerous than no minimum limit because the designers have to bulid a car at 700lb with 100lb strength instead of doing a 700lb car with 700lb strength.

The weight is 1000 lbs on the grid, with driver and fuel. There isn't really 300 lbs of ballast which would be stupid, agreed.

That said, even with strict regs it's not exactly cheap racing. They got around a dozen cars at their nationals at USRRC last year and are hoping for two dozen this year (woo hoo). Personally, I don't think it's going anywhere. I'd love to be wrong about that, but the problem here in the USA is not a shortage of racing classes. In the SCCA National categories alone there are 25 classes.

[NRoshier]

Originally posted by Fat Boy


But, the rest of the car was made with al dente pasta, so..........

They do use an unusually open arrangement of tubes, well spaced and a lack of triangulation too. The panels are supported by carbon fibre angles, which seems a brave move from the galvanic corrosion front.
They did suggest a torsional test figure of around 15,000 lb/ft - deg. Though how that was measured I have no idea.
Have you had a look at the cars in the flesh?

[Bill Sherwood]

Originally posted by dead_eye
Bill- have you got any more pics of that chassis? looks very interesting!

Yep, go here ->
http://www.billzilla.org/newrcar.htm

FWIW this is the car it's replacing ->

http://www.billzilla.org/rcar.htm

And this is the long rebuild it's undergoing - You can see the small improvements I've made to the chassis.

http://www.billzilla.org/rcar2.html

You should get some good information out of all that.

[NRoshier]

it may be the only car in the world taking longer than mine...we could have an unofficial construction race!

[Bill Sherwood]

Originally posted by NRoshier
it may be the only car in the world taking longer than mine...we could have an unofficial construction race!

Um we build the Fraser and also rebuilt the current racer in the mean time.

I'm hoping to start on the Mallock in the next couple of month, I just have to defrag the garage so there's space and I can find all the tools.

[NRoshier]

so, in effect you are saying you have too many cars, not enough women and need to give one of the former to a hard working but skint publisher you know?

[cheapracer]

Originally posted by NRoshier
so, in effect you are saying you have too many cars, not enough women and need to give one of the former to a hard working but skint publisher you know?

He doesnt have any women to spare as you pointed out.

Surely you couldnt be stupid enough to think that a man would give up a racing car?

[cheapracer]

Originally posted by McGuire


The weight is 1000 lbs on the grid, with driver and fuel. There isn't really 300 lbs of ballast which would be stupid, agreed.

Rule H1. N: "MINIMUM WEIGHT - minimum weight is 1000lbs"

There is no more detail, what am I missing? I did download the PDF regs some time back, maybe theres been an update to confirm your note?

Its not stupid, a 300lb steel plate floored car is going to go around a corner faster than a car with the weight evenly distributed throughout - as per F1 practice.
I note that the similar Jedi Racecar series cars (UK) are around the 650lbs mark and the very substantially framed (of steel) Gloria race series (Italy) complete with the heavier Yamaha Fazer 1000cc (in difference to the R1 engine) are at 850lbs ready to go.
I beleieve the 1000lb weight rule was to encourage older FC class cars to be modded and be competitive.

An interesting rule is the engine rule:

E. ENGINES
1. Motorcycle-based 4 stroke up to 1000cc

It does not clearly mention how many you can use, in fact the sub title is in plural form, he he.

[Bill Sherwood]

Originally posted by NRoshier
so, in effect you are saying you have too many cars, not enough women and need to give one of the former to a hard working but skint publisher you know?

Yes, no, and no.

[Fat Boy]

Originally posted by NRoshier

Have you had a look at the cars in the flesh?

Yup. They didn't race it much, so I don't really know it from head to toe or anything. I just remember thinking 'What were they thinking?'.

On the racetrack, it was really entertaining to watch Maxie hustle it around. One of the more evil handling racecars I've seen in a professional series. One driver told me that he was hoping it'd break at Daytona so he wouldn't have to drive it any more. It didn't, and they won. Go figure.

[NRoshier]

what did you think of the mixed chassis construction?
Also what did you put the evil handling down to?

[McGuire]

Just my $00.02 but as I see it the Multimatic suffered for being the first scratch race car by a tier-one auto supplier so it looked good on paper, then became obsolete before it was ever properly sorted. The early-gen DPs were at a significant disadvantage to the cars that followed as the designs were frozen to a large degree by the rules. Same thing happened to the Fabcar and Doran. Nothing wrong with the mode of construction per se and DP rules require a tube frame, though the execution can be critiqued. Lola and Tracy Krohn have since purchased Multimatic's Grand Am constructor's license.

I looked the car over semi-closely once, parked next to the media center at Talladega as part of a promotion. I figured it was a mule/show car of some kind. Then somebody said nope, that's the class-winning car.

Anyone seen the Dallara DP? Wooie it's homely.

[McGuire]

Originally posted by cheapracer


Its not stupid, a 300lb steel plate floored car is going to go around a corner faster than a car with the weight evenly distributed throughout - as per F1 practice.

To me that would not make a safe and economical club racer. Instead of 300 lbs of ballast let's put the mass in strong and affordable structural materials.

[NRoshier]

I fully agree that the DP's are not a good looking car, which is a shame as it is part of what is needed. Still they were designed with a purpose of providing safer and dare I say slower racing than the previous cars.
I was puzzled by the very simple multiple box structures tacked onto each other and the unusual bar in the middle of the w'screen, which I assume was an anti intrusion device ala' Nascar?

[cheapracer]

Originally posted by McGuire


To me that would not make a safe and economical club racer. Instead of 300 lbs of ballast let's put the mass in strong and affordable structural materials.

I couldnt agree with you more and its the fault of the rule makers that the situation is as it is. I argued with them to the point that I got kicked out of the forum. But what would I know, let them run their 20 car National series with 5 or 6 $80,000+ cars up front that will dwindle down to a 10 car series with which they will have to combine with another class that went the same way - as usual.

This is sad, this class had the potential for a real future too.

I still cant believe Race Governing Bodies around the world continue to make the same mistake.

[p261brm]

Throwing my nine pence worth in, owt wrong with good old T45 tube as frame material?

Originally posted by dead_eye
Afternoon all, ive got a few idiot questions for you! ive been trying not to ask them but im no materials engineer and everywere else i look for info on this baffles me!

Im just about to start building the spaceframe chassis for my new track, and ive poured everything ive got into it (its even a true spaceframe-feels good to be 5'6 and 10st ) But now im coming to the building point im looking at other options i didnt really consider before, probably due to cold feet and trying to delay it all :

so first off, has anyone heard of or seen a titanium spaceframe/ rollcage before? Im contemplating building the front and rear subframes from ti but there seems to be a distinct lack of it use in this area. It maybe because the teams with the money for use cf monocoques instead or ive missed something in its stats that makes none of its grades suitable for the job?? like i said im no materials engineer.

Secondly, ive got a supply through work of various carbon fiber honey comb panels with various different materials but mainly ally honeycombs. Ive seen a few top end cars now using these for their bulkhead panels and floor panels due to the superior stiffness off them. How ever all the materials i seem to find on them are sae style papers etc and to someone whos never come across them before quite baffling! So if anyone could fill me in on the details it would be much appreciated. i.e are they a design in material like a pre peg component with the fibers the right way etc or is it like and ally sheet that can just be bonded on, that sort of thing really as there more than a bit alien to me.

thirdly does anyone know of a reliable way to bond steel tubes to carbon fiber tubes? im looking at removing some of the smaller non critical triangulation pieces in chassis and replacing them with carbon tubing to help bring the weight down. However other than a mechanicall bracket (like those used in bolt in roll cages) i cant find a reliable way of doing it? perhaps a stressed sheet over the whole section would resolve the problem better?

Ohhhh why couldnt i just be happy with what i had lol now im all confused again!

The cars a closed top single seater btw est finished weight 690kg with a 49:51 f:r weight split.
Its subject to no regs and ideally the front and rear subframes will be removable and replaceable as 1 unit to facilitate complete fresh suspension/ engine changes etc as my crazy learning curve needs to test its theories on.
thanks, harry

[NRoshier]

T45??

[murpia]

Originally posted by p261brm
Throwing my nine pence worth in, owt wrong with good old T45 tube as frame material?

Sourcing T45 outside the UK might not be very easy...

Regards, Ian

[dead_eye]

p261brm- yeah t45 would do the job and ive worked with it before but as i say this a personal project for my engineering passions aswell as driving so im looking at alternatives to.
One of the guys i work with used to layup carbon suspension components and mounting brackets so hes running through the basics of using cf structurally and the various grades and resins etc. So far its looking like a t45 safetycell/cockpit and eventually tubular cf front and rear frames. i was tempted to go the hole hog but i want a proper steel frame around just incase especilly on a first build.

unfortunately its all been slowed down by the van driver that decided to pull across the road i was doing 60 down right in front of me yday I bent the steering wheel with my head lol in what the paramedics and police both thout was a fatal accident on arrival! So im under strict orders to nothing for a few weeks!

[robroy]

Hope your steering wheel's straightened out now.
This may or may not interest you or others:


Note bamboo frame in background.

http://www.bmeres.com/c-thruframe.htm

[NRoshier]

I've seen the bamboo frames before and had contemplated making one. The girder frame would be hard to clean.

[cheapracer]

Living here I have become blown away by bamboo, it's amazing stuff, stronger and lighter than you could imagine if you haven't played with it.

bamboo scafold example here - http://www.travelblo...hotos/9874.html

Tastes great too, Chengdu actually has a few dedicated bamboo only restaurants.

[Slow M]

Keep in mind 4130 can be joined by sweating the joints w/ brazing via capillary action as an alternative to welding.
Porsche made a magnesium frame for the 917. Driving that in earnest would make me a bit nervous.
BH