Aerodynamics

[Julian5]

I am currently engineering my v2 version of my f1 in schools car, it is a small scale car powered by a co2 cartridge designed to go down a 25m track, my current version does 25m in under 1.4s, however, I would like to shave off another 0.3-0.2s I believe my main issues are the bearings (only ceramic hybrids) and the weight. It weights about 70g I believe. I have attached pictures of the model and the one I am currently designing to be CNC'd. Will taking material off the side of the body underneath improve speed, any tips?

https://i.gyazo.com/d10bb98329a639e96fbd9d942d0da553.png
https://i.gyazo.com/dd0c44a7416831d6905dab4849031632.png
https://i.gyazo.com/b4f70659cfef30fe55607dee724c5fd3.png

As you can see on the second model the  front wing has a little funnel to direct the air into the under slot, should I place the wheel as high or low as possible?
 

[Thunderpup]

This isn't my forte, but i have a question about the split wing design for the front.

 

Is there a reason you are trying to funnel air that way? Because i'm thinking doing so adds unnecessary drag especially since the air only ends up crashing against the tire.

 

Also is it possible to mount some, if not all, the tires internally?  I know a lot of the rocket cars that go for land speed records have the tires inside the body to reduce drag.

 

If you haven't already you could look up pictures of the bonneville salt flats speed record holders for some inspiration. 

 

 

 

 

[Julian5]

I agree with your first comment and I designed them for esthetics (dumb me) but the wheels are as enclosed as the restrictions allow. To be honest I doubt aerodynamics are the main factor but Weight is the issues. I will try printing the PLA parts in a lower density.

[Thunderpup]

2 minutes ago, Julian5 said:

I agree with your first comment and I designed them for esthetics (dumb me) but the wheels are as enclosed as the restrictions allow. To be honest I doubt aerodynamics are the main factor but Weight is the issues. I will try printing the PLA parts in a lower density.

Just be careful if you decide to remove material from the body.  Any cavity you open up could create air pockets and turbulence that more than offset the amount of material you removed.

 

Is the body one solid piece?  If so is it possible to have certain sections be hollow?

[TVwazhere]

Does it have to look like a F1 race car? If not, just trim off literally as much weight as you can. Aerodynamics really only matter when you start going really fast. I would try to make the body sides hollow, leave them to have 1/8th thickness. Weight reduction will increase acceleration. Aerodynamics will just decrease the rate at which drag affects your car, which at this sizer, speed and track length isnt as big of a factor. (I did this project in my 7th grade class but it was hand made with wood, the winner jsut happened to be the lightest)

[Bananasplit_00]

6 minutes ago, TVwazhere said:

Does it have to look like a F1 race car? If not, just trim off literally as much weight as you can. Aerodynamics really only matter when you start going really fast. I would try to make the body sides hollow, leave them to have 1/8th thickness. Weight reduction will increase acceleration. Aerodynamics will just decrease the rate at which drag affects your car, which at this sizer, speed and track length isnt as big of a factor. (I did this project in my 7th grade class but it was hand made with wood, the winner jsut happened to be the lightest)

its going almost 65km/h, i would say some downforce is quite needed. but probably not as much as there is in these scetches.

 

make the body as low weight as possible and settle for a lesser angle on the front wing and makeing it a solid thing could help a bit more

[Julian5]

I am gonna stay with the chassis design however I think I am going to try and reduce as much weight as possible on the wheels and ailerons. the minimum weight is 50g