1268 replies to this topic

[Aerodynamic]

Wouldnt it be better to use air as middle layer?

Br, Per

In any laminate its the outer layers that do the work. using a glass core is a way of adding thickness without costing a fortune. Might be this?

[2-20]

It's a bit difficult to bond I think...

[FLD]

You'd use foam or honeycomb to include air. You need some sort of link between the skins.

[Aerodynamic]

Yhea I kinda know. Is it expensive?
Which is lightest to its thickness? Glassfibre or carbon fibre?

You'd use foam or honeycomb to include air. You need some sort of link between the skins.

[FLD]

It can get expensive if you're not careful. In terms of value I'd go for some 3mm pvc foam. For ultimate lightness I'd go for nomex honeycomb. For convenience soric is OK but it's quite a heavy core.

WRT lightness per thickness there's not much in it in the thicknesses we use but the stiffness (ooer) will be very different. This assumes same resin, no core, etc. For panels I've been favouring 2x200g twill/foam/2x200g twill. It gives a nice compromise between weight / strength and durability.

[2-20]

Glassfiber is the heaviest...
The lightest is Kevlar but carbon is very close.

[Doctor Ed]

best stuff ive got locally is 3D Core. It runs at about €10-15sqm i think. not expensive, and available in various thicknsses - but as space under the car is very very tight, and the diffuser is supported at multiple points across ist surface, i opted for thin-ness (ie no core) over stiffness. im pretty certain ist going to be stiff enough

and yeah glass CSM is heavy stuff... the fiber:resin ratio is terrible (i think 15-20% fiber mass) which is half that of CF (ie twice as much resin). but as mentioned, its actually pretty cool stuff, the polyaxial fibers contributing to the overall strength of the piece. its also cheap

this thing literally used up the entire 10sqm CF twill i had on a roll, and thats only 3 layers )plus reinforcing and overlaps). €25sqm adds up quick!

Edited by Doctor Ed, 31 May 2019 - 01:55 PM.

[FLD]

I used 3d core in my undertray with solid carbon around the mounting holes.  It gives a nice stiff laminate but it is quite heavy.  If I were to make mine again I'd just use foam, or solid like you are doing.

[Doctor Ed]

id say this will make a very useable part :yup:

in the middle of laying things up



first look at the cured part sitting on the mould



"popped" off the mould (aka destroyed the fcuking mould)



mmmmm carbon/kevlar:



jury is still out as to whether its stiff enough in parts. will need to let it cure fully, then look at whether something else i needed

[Aerodynamic]

Impressive work. I want to learn moulding carbon fibre.

 

Br, Per

[Doctor Ed]

fcuk yeah!

[Doctor Ed]

been working on some reinforcement spars and fine tuning the mounting. doesn't look much different, but who cares, here's some more pics

[Aerodynamic]

Again, very nice.
Im looking forward to see that thing real life flow tested. :-)

[Doctor Ed]

flow testing is going to consist of smoke flares and early morning Autobahn flybys

[Bargi]

flow testing is going to consist of smoke flares and early morning Autobahn flybys

 
Some DIY hints and tips for measuring Aero... guy is even a fellow Ozzie
 
Measuring car aerodynamic panel pressures https://youtu.be/OuSf3K6yuMc 

Aerodynamic tuft testing of cars https://youtu.be/CsREhs9zZTQ

[Doctor Ed]

wow, Julian Edgar. Blokes a bit of a tugger, and has obviously been on a video making binge to push his new book. very 1990's but not entirely wrong either.

Edited by Doctor Ed, 03 June 2019 - 08:17 PM.

[Bargi]

wow, Julian Edgar. Blokes a bit of a tugger, and has obviously been on a video making binge to push his new book. very 1990's but not entirely wrong either.

 

ha ha, fully agree

[Doctor Ed]

Because working with carbon is so much fun!!

[Doctor Ed]

Had a spare 30mins... so smoke flare, woll tufts, GoPro, big ass leafblower. Tested at 100mm ground clearance.

Flow attachment baby!! All the way to the end

[Aerodynamic]

Nice very nice. If or when I make a new diffusee I will go a bit more aggressiv.
Maybe not this much since my car seems to produce some downforce with my latest setup.
What was the maximum angle you had on this?
Did you use Epoxi or Polyester resin with carbon for this?

Br, Per