Lightyear's SE Replica Track/Road MX-5

[beavis]

[stuart1]

Working with aero can be quiet time consuming and frustrating.

It is not until you get to the really fast tracks that you realise how strong these aero devices and their mountings have to be.

Then you have springs and suspension travel plus clearance issues and possible tyre damage until you discover and fix these issues.

It is very difficult to let your driver know one of his tyres is smoking badly due to body contact induced by a rear wing down force that you could not produce even with 2 100KG persons sitting on that corner.

Aero forces and the load they impose can be quiet startling.

Once you get all your package working you have to also see a benefit on the stop watch as even though your car should be more stable at high speed your VMax will be down and may counter what you are trying to achieve unless you have ample engine power.

Even if you are able to get all this working your setup may not work on slower tracks due to the heavier springs you may have had to use with aero on the fast track.

Yes it is not just a matter of bolting on a wing (most of which will fall apart at high speed anyway) and expecting gains.

One thing for sure though is the MX5 has a short wheelbase and you certainly don't want the rear stepping out in turn 1 at EC or PI so aero assist will help there but create other problems if you are really just inducing understeer as in that case EC and PI will eat your front tyres.

Yes aero is not easy but I applaud anyone who is trying it and especially in this case where they are giving public feedback.

Thanks for the video comparison.

[mx5002]

Great comparison, you can really see how much more effort it takes to keep the car straight. Love the oversteer across the crest when the car gets light

[lightyear]

Yep, aero set up is tricky to get right. I have never gone out with aero that has been "right".
Mostly due to not enough time or no budget. Or just a little lazy thinking that will be good enough.
The new aero package should be a lot better. Probably 12hrs work in it this time. And cost, nothing so far except materials that are lying around.

Front splitter/undertray is done now. I had to cut the splitter back to 50mm from the bumper as per Clubsprint class rules. I want to enter the Vic Time Attack on the 1st of April. I know I can't win, but will be interesting to see how it goes against the best cars built in the country.
Mine will probably be the cheapest car in the class. But I am hoping that my advantage of home track will help. Some guys have never dríven at P.I that are going. If I get into the top 10 I will be happy.

New front splitter.


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[lightyear]

Also have new front wheel bearings. The rear wing has had the uprights deleted, and new end plate extensions. Also have a gurney flap on the second element now, and it's all finished. This pic is when I was making it. I am going to put some cable to help support it and stop sideways movement from one of the bolts to the boot gutter.
This should all work properly and not fail, I hope.








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[Magpie]

Did you change the spring rates for the extra force of the rear wing?

stuart1 great post!

[lightyear]

Nope. Just running the road springs - 6 and 8kg. The front is the problem. It needs much stiffer springs to keep the tyres away from the chassis above. Would like to try 10kg in the front to start with.

[lightyear]

I made a Camm tail for the boot, but had to leave a gap to open the boot. Race tape will fix that when I am at the track. Gurney flap is on the 2nd element. Just need to put the rear bumper back on, then brace the centre of the Camm tail. Keen to try this out.


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[Waz man]

So with a wing on, on one of the fastest tracks in Aust it is only 1 second faster???

[davekmoore]

So with a wing on, on one of the fastest tracks in Aust it is only 1 second faster???

It's another second faster, and seems more driveable - not that I'd know much about it, being over 10 seconds slower.

[lightyear]

So with a wing on, on one of the fastest tracks in Aust it is only 1 second faster???

It's not just a wing. You need front downforce to match. A wing and aero package could be worth several seconds depending on the car and wing/aero.
A wing alone may only give 1 second. So many variables.
The run without the wing in the video was with a big front splitter and undertray. So too much front downforce, not enough rear, hence the oversteer in the video.
And the run with the wing, was with the monster rear spoiler also attatched to the car. So way too much drag. Top speed was 21km/h slower.
Plus, I only did 2 fast laps with each set up. I need to play around with it until it is optimised to get real lap time differences. The car will drop a lot of time on the next outing.

When I did the 1:50.1 with the NA8B, it had the wing set very low (at the back edge) so I could steer the car. So I have never dríven with this wing set at positive to zero angle. So never had a chance to see how much it can help. Except I did drive Brendan's car with better balanced aero, and the wing set to normal position. The car was very easy to drive, and needed much more power (almost too easy to drive). Basically you drive 90% of the lap with your foot flat to the floor.

[NitroDann]

It needs power for the downforce package, the downforce package is probably too aggressive for the power level.

[stuart1]

It needs power for the downforce package, the downforce package is probably too aggressive for the power level.

+1

Most down force means extra drag = speed loss = more power needed.

Even when you get down force right for increased corner speed your straight line speed loss may result in a negative overall outcome.

It is a balancing act with the final decider being the stop watch but having said that down force on an MX5 with its short wheelbase should give you a lot more confidence to drive harder on a high speed track.

[Tim_cyc03]

Great end plates! If you don't mind sharing how many layers did you use and what material?

I've been keen to try and make some but I'm worried they would fail.

[lightyear]

I used 8 layers of 200 gram plain weave carbon fibre with 2 layers of 1.5mm Soric for the core. It feels very strong.
This is hand layed up with a brush, so anyone can do it. Best to make the part out of alloy, then use the alloy for a mould.