[KVRC] SR71 2016

Post here information about your own engineering projects, including but not limited to building your own car or designing a virtual car through CAD.
SR71
16
User avatar
Joined: Wed Jan 27, 2016 8:23 pm

[KVRC] SR71 2016

Post by SR71 » Sun Feb 28, 2016 1:35 am

Wanted to start a thread dedicated to my car. As this is my first year I appreciate any tips/insight...

The car is under development for the first few high down force circuits, I'm reposting the Launch Spec images and livery along with launch simulation results. Also including a new view...

Image

Image

Image


Launch Simulation Stats:

Total drag: 1089.56 N
Front wing(s) drag: 67.86 N
Rear wing(s) drag: 213.68 N
Other wing(s) drag: 0.00 N
Drag coefficient - Cd: 0.55
Drag area - Cd.A: 0.91 m2
Total Downforce: -2255.49 N
Front wing(s) downforce: -991.41 N
Rear wing(s) downforce: -1655.36 N
Other wing(s) downforce: 0.00 N
Downforce coefficient - Cl: -1.13
Downforce area - Cl.A: -1.88 m2

CoP of downforce: 4.077 m along streamwise (Y) direction from Y = 1.17 m.
KVRC Only: Corrected CoP of downforce: 2.863 m along streamwise (Y) direction from Y = 1.17 m.

Surface Pressure:

Image

Image

Drag/Downforce:

Image

Image

Thanks,
SR71

machin
180
User avatar
Joined: Tue Nov 25, 2008 1:45 pm

Re: [KVRC] SR71 2016

Post by machin » Sun Feb 28, 2016 8:08 am

I think your Origin is in the wrong location: it should be on the front wheel centre-line (this is making your COP look much worse than it really is).

You definitely need to put on a "double inflection diffuser": there's a profile section in my guide that you can copy...
COMPETITION CAR ENGINEERING -Home of VIRTUAL STOPWATCH

CAEdevice
36
User avatar
Joined: Thu Jan 09, 2014 2:33 pm
Location: Erba, Italy

Re: [KVRC] SR71 2016

Post by CAEdevice » Sun Feb 28, 2016 8:19 am

As Machin wrote I have doubts about the center of coordinates, but from the chatrs, I wuold try a more aggressive front wing and a bigger angle of attack for the rear diffuser. For the first 2 races, even 1500N of drag would be accetable, for the last three (efficiency races) 1000N is ok (excpet for my car that has a completely different design concept, where maximum efficiency is reached with more drag than the average).

SR71
16
User avatar
Joined: Wed Jan 27, 2016 8:23 pm

Re: [KVRC] SR71 2016

Post by SR71 » Sun Feb 28, 2016 8:51 am

CAEdevice wrote:As Machin wrote I have doubts about the center of coordinates, but from the chatrs, I wuold try a more aggressive front wing and a bigger angle of attack for the rear diffuser. For the first 2 races, even 1500N of drag would be accetable, for the last three (efficiency races) 1000N is ok (excpet for my car that has a completely different design concept, where maximum efficiency is reached with more drag than the average).
I'm having massive difficulty exporting properly coordinated geometry out of solidworks. Currently I'm hand tuning all final positioning in paraview, not very effective.

I'm building my CAD with 0,0,0 on the front wheel centerline and floor on 0, still no luck exporting. These simulation results are also old. Currently im around 4k downforce and 1400 drag with a 45/55 balance. Hopefully I can get more out of it before the first race.

I wanted to share the baseline simulation results so you guys could see what was actually happening with the rendered geometry I shared.

New development share-out coming soon.

Thanks,
SR71

CAEdevice
36
User avatar
Joined: Thu Jan 09, 2014 2:33 pm
Location: Erba, Italy

Re: [KVRC] SR71 2016

Post by CAEdevice » Sun Feb 28, 2016 9:13 am

Your car will work better on efficiency tracks (last three): I quite sure you can add at least other 500N working on the rear diffuser and 500N from the front axle area, without exceeding 1500N of drag (you should have a df/dr ratio above 3 as a target).

What about the cooling requirements?

LVDH
27
User avatar
Joined: Tue Mar 31, 2015 1:23 pm

Re: [KVRC] SR71 2016

Post by LVDH » Sun Feb 28, 2016 11:36 am

Well turning the car to the right direction is the first step and will probably be the one that improves the car the most.
But yes, now you have to move it to the correct coordinate system center to correctly determine the center of pressure CoP.
I wonder how you got it so wrong. You should take the guide files and make sure that your car fits into them. Then also take the provided wheels and make sure they fit to your car.

Your car shows some first good features:
  • The splitter is red on top
  • Underneath it is blue
  • Some nice blue where the floor starts
  • Blue infront of the rear diffuser
And you can now learn how to read those force development histograms. The downforce plot shows bars going upwards more or less at the wheel locations. If you look at the pressure picture of your car you will notice blue between the rear wheels looking from above. This is lift. You do not want that. You should avoid dark blue areas on top of the car. Here you will have to come up with something and fix it.
The lift bars at the front end of the car are most likely your suspension covers. This is probably the most challenging part to design in this competition. On the pressure picture you can see that this area is red when you look from below. This is not good and could indicate that the air flow in your front diffuser is detached.

However coming back to CoP you will notice that getting rear end downforce is not so difficult as soon as you have incorporated a rear diffuser like suggested earlier and maybe a very good rear wing.
I think after you have that getting the car balanced will be difficult with your design. You should go to the virtual stop watch and check how much of a difference it makes to have a balanced car or not.
After that you should have a good look at Variante's and JJR's high downforce cars of last year.
I think you will have take out some of the beauty of your car and replace it with an extreme front wing.

CAEdevice
36
User avatar
Joined: Thu Jan 09, 2014 2:33 pm
Location: Erba, Italy

Re: [KVRC] SR71 2016

Post by CAEdevice » Wed Apr 27, 2016 8:10 pm

Any chance to see it racing for the next race?

SR71
16
User avatar
Joined: Wed Jan 27, 2016 8:23 pm

Re: [KVRC] SR71 2016

Post by SR71 » Thu Apr 28, 2016 4:09 am

CAEdevice wrote:Any chance to see it racing for the next race?
For sure I'll make an appearance. Just need to make sure it's the one I can win :-)

For real though losing multi core support threw me for a little while, I don't like going backwards with regards to technology.

This was always an aero competition in my eyes and cooling was an interesting and valid challenge but having multiple and complicated cooling options that stripped us of simulation time felt like a step backwards in time. The future will see less and less cooling and I felt KVRC was a leader in future race car design. We will NEVER escape the effects of air pressure on a race car (on earth) so it's a bit ridiculous to sacrifice aero research and development for cooling simulation (something that will soon be dead).

As I understand it, option 1 is similar to last year which is acceptable and shouldn't prevent me from rolling back my one-click to a previous (and more advanced) version that supported multi core simulations.

Love,
SR71

CAEdevice
36
User avatar
Joined: Thu Jan 09, 2014 2:33 pm
Location: Erba, Italy

Re: [KVRC] SR71 2016

Post by CAEdevice » Thu Apr 28, 2016 6:22 am

I have good news: now multicore works perfectly (Julien switched to a different OF porting). :)

About coooling: the new rules improved very much realism and the design is much more interesting from my point of view. The cooling options are only two and, compared to 2015, the rules are quite simple.

No cooling meeded on future cars? Well, are the thermodynamics laws going to change? :)

Seriously: I liked your car and it would be great to see it racing.

SR71
16
User avatar
Joined: Wed Jan 27, 2016 8:23 pm

Re: [KVRC] SR71 2016

Post by SR71 » Thu Apr 28, 2016 4:28 pm

CAEdevice wrote:I have good news: now multicore works perfectly (Julien switched to a different OF porting). :)

About coooling: the new rules improved very much realism and the design is much more interesting from my point of view. The cooling options are only two and, compared to 2015, the rules are quite simple.

No cooling meeded on future cars? Well, are the thermodynamics laws going to change? :)

Seriously: I liked your car and it would be great to see it racing.

Cooling will always be important, I didnt mean to suggest otherwise...

I will upgrade again to the latest One-Click... That is great news, thanks to Julien for the hard work!

CAEdevice
36
User avatar
Joined: Thu Jan 09, 2014 2:33 pm
Location: Erba, Italy

Re: [KVRC] SR71 2016

Post by CAEdevice » Thu Apr 28, 2016 6:02 pm

Ok, take care about the installation of openmpi (or equivalent), this is the critical point.

LVDH
27
User avatar
Joined: Tue Mar 31, 2015 1:23 pm

Re: [KVRC] SR71 2016

Post by LVDH » Sat Apr 30, 2016 7:55 am

SR71 wrote:... so it's a bit ridiculous to sacrifice aero research and development for cooling simulation (something that will soon be dead).
How soon will that be? Right now most race cars are getting smaller turbo charged high efficiency engines.
High efficiency creates higher temperatures for reasons every thermal dynamics book will explain within the first two chapters. So right here we already have higher demands on cooling.
Turbo charged engines need charger air cooling. This is another big heat exchanger, or as you can see on the Mercedes F1 even two.
Then cooling electronics and batteries of the electric propulsion system does not seem to be a big thing but from what I know it is important to keep the battery in the sweet spot for optimal performance.

So I do not see how cooling is currently loosing its importance, rather the opposite.

SR71
16
User avatar
Joined: Wed Jan 27, 2016 8:23 pm

Re: [KVRC] SR71 2016

Post by SR71 » Sun May 01, 2016 1:16 am

LVDH wrote:
SR71 wrote:... so it's a bit ridiculous to sacrifice aero research and development for cooling simulation (something that will soon be dead).
How soon will that be? Right now most race cars are getting smaller turbo charged high efficiency engines.
High efficiency creates higher temperatures for reasons every thermal dynamics book will explain within the first two chapters. So right here we already have higher demands on cooling.
Turbo charged engines need charger air cooling. This is another big heat exchanger, or as you can see on the Mercedes F1 even two.
Then cooling electronics and batteries of the electric propulsion system does not seem to be a big thing but from what I know it is important to keep the battery in the sweet spot for optimal performance.

So I do not see how cooling is currently loosing its importance, rather the opposite.

I can see how one would naturally arrive at that conclusion in a petrol based future. Unfortunately for me I dont live with that same vision - electric is going to swamp petrol racing within a decade - probably within 5 years.

Apple and Google both are spending billions on battery research (these batteries will be on the market in under 5 years if you trust some inside sources). Combined with the work done by Tesla we are looking at a battery revolution not decades in the future but a few years.

There is no doubt at all electric motors, pound-for-pound are far more powerful and efficient than any petrol engine. We just need lighter batteries and as I stated above this isnt far off.

Yes, racing cars will always be on the limit and will run hotter than production cars but we're already seeing the effects of minimal airflow into electric cars and racing will benefit from the same.

This will be a 180mph car. Check out the minimal cooling:

Image

This is a car that does 0-60 in under 3 seconds (and is much faster than a FE car):

Image

No doubt this car will receive the same updates over its lifetime that the model S received - and no doubt that tesla could 'unlock' this car to be faster than a Model S. Note the cooling.. or lack of:

Image

The future is coming whether we like it or not - cooling will be something we remember akin to hand crank starters on race cars.

It would be awesome if KVRC decided to say we are a future racing league and we focused on the main point - aero.

CAEdevice
36
User avatar
Joined: Thu Jan 09, 2014 2:33 pm
Location: Erba, Italy

Re: [KVRC] SR71 2016

Post by CAEdevice » Sun May 01, 2016 6:59 am

It is funny: none of the car mentioned above has aero development (one of them does not exist at all), except for drag reduction for Tesla.

On the contrary, Formula E, that is a real race car, with basic aero performance, seems to have radiators.

Image

Image

Anyway: cooling added realism and made the design more interesting in KVRC, but a good project in 2015 is still winning in 2016 (with advanced cooling). See MantiumRay for example.

Will we see you at the Nurburgring or in Monaco?

LVDH
27
User avatar
Joined: Tue Mar 31, 2015 1:23 pm

Re: [KVRC] SR71 2016

Post by LVDH » Sun May 01, 2016 9:11 am

Yeah, somehow strange that when you use technologies with less then 100% efficiency you need cooling.
Also showing passenger cars seemingly without cooling intakes is a bit misleading.
Today’s dinosaurs only seem to have huge cooling intakes. They are black but mostly blanked. This way the standard 120bhp mini crap car looks super aggressive and fast. Also I think the designers cannot come up with anything more creative.

Going full electric, the aero-accoustics of the car get much more important as they are not overlayed by the ICE. That is why a Tesla looks and is more sleek. However I highly doubt that you want to go for aero-acoustic simulations using conventional CFD software. But AAC simulations are what is gaining importance right now in the automotive field.
CAEdevice wrote: Anyway: cooling added realism and made the design more interesting in KVRC, but a good project in 2015 is still winning in 2016 (with advanced cooling). See MantiumRay for example.
I am pretty sure that MantiumRAY messed up cooling for the next race. Yet, the car was submitted.