The Passion Car

[Kambu]

PASSION
The challenge to build the best trackday car in the world.

There are many ways to describe „Passion“ the easiest way for the reader to understand is probably to explain it as the passion being the foundation. Its the only thing I had in the beginning, a passion to build the ultimate car, car faster than any other, everything else came later. My passion was fuelled by my father, engineer, businessman, kart driver and coach. That was even before I was self-aware of my passion. Its always been there, but every year it keeps getting bigger, the more you learn the more you want to achieve, there is no end. When you are truly passionate about something it becomes a curse, you start projects, but you learn in a pace that makes the original idea out-dated, then you start another, and the circle continues.
The beginning is the hardest, having wild ideas, too wild to tell anyone in the fear that they will think you are insane. Some people will never get over the fear I guess, others just dont have the ideas, ive been lucky, I had help. There have been several projects in the past, they have failed. The reason: Fear of others seeing you fail.
That fear leads to not asking for help, its unprobable that an uneducated 26 year old can complete a project of this magnitude without running into problems, add the fear of asking help and you´ve got a failure. This post is here to remove that variable in the equation, an attempt to keep my Passion alive through your comments and feedback.

The First Concept:




Any advice on how to improve the aerodynamics of the car very welcome, Dont get into too specific with the dimensions of things, its a first concept and should be treated as such, feel free to ask for additional images of specific areas.

[flynfrog]

Before you can work on the aero you have to set your goals, know your engine power what track are you planning to run at ect.
Off the top of my head the planes off of the nose look to be producing lift. The front wheels could be faired in better. Not sure you will have enough front DF to balance out your massive rear wing.

[Kambu]

I havent decided on the engine yet, but the power output will be somewhere between 600-800bhp, The idea is to run it on European Road Courses.
The original idea was to use a GM LS7 engine together with a Hewland Transaxle, but that isnt something that i have decided on
If someone knows how well does the GM LS7 engine take over revving on downshifts, and other driver related errors? What I am looking for is an engine that is powerful, and bulletproof. If you can think of any gearbox-engine combo that would work well for my application just shout it out. Should be a sequential gearbox.

You are right about the wheel arch supports probably producing lift, I will fix them.
What options can you think of to make the front end produce more downforce? I will change the rear wing for a smaller one. As far as the rear wing design, is it safe to assume that having the endplates connect to the rear bodywork is a more efficient design?

[wesley123]

Seeing the tire width front to rear, the balance seems to be much more rearward(my guess) thus making front DF less of a must.

I do like the front end treatment with the wing and the wide tub(wide enough to fit two people?), together with the clean path and the front wheels/fenders it seems to be though out fairly well. Treatment of air behind the front wheel, plus exiting air from the front wing seems to be much more complex than anything else on the car.

I disagree with flynfrog that the front wheels could be faired in better. Well, I do agree it could be done, but with that you'd increase frontal area, as the fender has to incorporate room for the front wheels to turn, making the fender wider, this in turn would also reduce area between the tub and fender.

On the rest, I agree with him. Setting goals to what to achieve(I wouldn't call make the best track car in the world clear enough) and what you have to work with. Getting a good idea what to achieve, and what you have to achieve that is important for pretty much every project in any field of work.

[flynfrog]

to clarify what I was talking about on the front wheel it looks like your pods end in a square edge I would try to make the top view more of an airfoil shape. Or you could make them flow into the side pod. I am guessing those will need to be bigger once you figure out your cooling requirements.


Not sure if you have seen it but check out http://www.DPcars.net


When I see stuff like this its really best to start with the basics. The car looks really good but as wesley pointed out much of the airflow looks complex which probably means it doesn't work and is extra draggy . Maybe dig on this site a little and look at the CFD challenge cars its not the fancy looking ones that do well.

[Kambu]

Thanks for the feedback guys!

Currently working on still blocking out everything.



I do agree that the sidepods are probably a bit too small. Trying to make everything airtight, and then might take a look at autodesk CFD. I will try to work on a more better description for the car, just got really excited in the modeling phase

[turbof1]

I see you took some inspiration from recent F1 ideas:
-Heavily undercut sidepods with airflow redirected underneath the bodywork over the top of the diffuser.
-A F-duct
-High nose.

I'd lower the nose. And bend it slightly into an aerofoil shape. It'll lower the front CoG and produce more front downforce. It'll take a bit of rear downforce away, but I think you have an abundance of that already.

[wesley123]

The original idea was to use a GM LS7 engine together with a Hewland Transaxle, but that isnt something that i have decided on
If someone knows how well does the GM LS7 engine take over revving on downshifts, and other driver related errors? What I am looking for is an engine that is powerful, and bulletproof. If you can think of any gearbox-engine combo that would work well for my application just shout it out. Should be a sequential gearbox.

Judging the engine and concerns surrounding I'd say you'd indirectly want a cheap to maintain engine. Thus, simply said, not an LS7(unless I'm wrong here). Seeing your base design I'd say a lightweight, compact engine would bring you more than a heavy, powerful engine, but that's always hard to say when the end goals are still unclear.

What options can you think of to make the front end produce more downforce?

Front diveplanes, louvres over the wheel well are a quick way to generate downforce. Judging on the front tire width, I'd say it would be good on downforce. Remember that the tires have to be able to take the load and carry it through the turns. You could increase front overhang a bit, but I would start taking a look where you are in the project before making (big) changes.

I will change the rear wing for a smaller one. As far as the rear wing design, is it safe to assume that having the endplates connect to the rear bodywork is a more efficient design?

Hard to say imo, Mulsannes corner has an article about endplate depth, but you don't want to over-complicate things quickly.

I have more concerns with the fin which will have to carry the load of the rear wing. Where is this fin connecting to? Due to it's length we can expect it to be heavy(placing this weight high up) and complicated. I'd say remove the fin as a whole and utilize normal pillars.

[Kambu]

Will be gone for a bit now, holidays here.
Not alot of progress on the modelling side, but I have been messing with the Autododesk Flow Design software, and making the mesh acceptable for it. Had alot of issues with scaling and some odd things happening when exporting from MODO.
Here are my first flowlines Alot of studying to do to understand everything.

[turbof1]

I have more concerns with the fin which will have to carry the load of the rear wing. Where is this fin connecting to? Due to it's length we can expect it to be heavy(placing this weight high up) and complicated. I'd say remove the fin as a whole and utilize normal pillars.

I disagree there. Yes it raises the CoG, but having the support this way keeps the underside of the wing, more important then the top of the wing, free from obstacles, increasing aero efficiency.

It btw still looks like an f-duct-esque tube. Kambu, are you intending to have the wing stalled at higher speeds?

[Callum]

Sorry to be 'that guy' but how far have you considered the safety aspects? Is there crash absorption? Air bags? How good do you expect the visibility to be through the pillars holding the windscreen in?

Also for the CFD have you removed the wheels? I'm not sure if this is done to simplify things but I would have thought blocking the wheel arches to simulate a wheel being there may produce more accurate flow results. You may find air bleeding out of the empty wheel holes when it may have stayed in-board going to your radiators.



Just to be clear, i'm not criticising, just voicing my thoughts. I think the design looks pretty cool .

[Tim.Wright]

I like this kinda stuff. Though its quite an optimisti goal you have set yourself. Its hard enough to build a car that runs let alone the best track day car ever.

I'd recommend some reading first up otherwise I can guarantee you will make a huge mistake somewhere and not realise it till its too late.

I'm designing a something similar albeit smaller engine and not only for the track:
http://www.f1technical.net/forum/viewto ... pen+source
There have been some pretty interesting discussions on chassis and suspension design in there.

This book is an excellent resource for a self build car. Its written by an engineer and there is a very good mix of theory and practical considerations:
http://www.kimini.com/book_info/

Definately pick up the set of Carrol Smith books including this one:
http://www.amazon.com/Engineer-Win-Carr ... roll+smith

Just my opinion but if I were you I'd also step back a bit with the design. You can't be doin detailed design of little aero parts on the car if you haven't sorted your overall layout. And you can't sort your layout until you nail down the overall goals. this means:

• Top speed
• Cornering performance (lateral acceleration)
• Stability/Agility trade off
• Grip/balance trade off?
• Short or long competition runs?
• Racing class
• Mantainability
• Running costs
  etc...

From these you can deduce your tyres, target mass and CG location, chassis construction type and powertrain...

With these defined, you then need to start on the layout which means to sort/buy/size the following large heavy objects:

• Engine
• Gearbox
• Fuel tank
• Driver position

And put them in the correct position with respect to the:

• Wheels/tyres

In accordance to hit your target mass distribution.

Then you can start stuffing about with things like

• cooling ducts
• wings
• diffusers

[wesley123]

I have more concerns with the fin which will have to carry the load of the rear wing. Where is this fin connecting to? Due to it's length we can expect it to be heavy(placing this weight high up) and complicated. I'd say remove the fin as a whole and utilize normal pillars.

I disagree there. Yes it raises the CoG, but having the support this way keeps the underside of the wing, more important then the top of the wing, free from obstacles, increasing aero efficiency.

It btw still looks like an f-duct-esque tube. Kambu, are you intending to have the wing stalled at higher speeds?

That's why WEC teams use swan neck wing mounts.

aero efficiency is the least of the troubles in that solution. As I said, it requires quite a bit and stiff beam to carry the wing loads. knowing how a lever works, the horizontal pillar will have quite a bit of load to take care of, not to mention flutter in general.

And then where does the pillar connect to the car? Directly to the tub? There it will have to acknowledge that it will cross the air intake somewhere, adding even more complexity to the mount.

I don't see any actual advantage compared to a regular swan neck mount. This single pillar definitely is going to be overly complex and heavier than a regular pillar.

[Kambu]

Excellent Post Tim!

People shouldnt have to get carried out with the overall design of the car currently, this whole thread is about the journey to get to the "best car".
If the first car I am planning to build gets to the final CAD stage, then even that is a huge milestone, if it gets finished that is superb, and then there will be improvements.
The image from the CFD program is just that, an image that shows that I have finally got the program itself working, the whole goal of it was to find a way to make quick changes to the 3D model, in a way that it would work in the CFD package aswell, (All 3d models must have thickness, and should be non self intersecting). Its not a CFD analysis, I have no experience or knowledge to carry out a detailed analysis yet.

As for the safety aspect of the car, the idea is to establish a general concept of the car, its looks its layout etc, then send the whole data to a engineering and manufacturing company in italy and refine everything. They will also build the monocoque of the car. I have helped to build a monocoque 2 years ago myself, but its not something that I would like to do again. Too much uncertainty, and I think its wiser to leave it to someone who has experience. I will try to write up a description of the car and the whole process when I get back from holiday. I also have a Formula Renault race next week which can postpone things even more.