Join the discussion for how to make project F-Dat an aerodynamic machine!

Is there a CFD software that will accept Sketchup files?  I can export what I did as a OBJ and i think STL conversions are available.

I left the rear wheels like that because it looks amazing.  I've always thought cars with bodies that just kind of end (Porsche 917) look the absolute business.  Also at at Challenge speeds it shouldn't mater too much.  The important parts (as I understand it) are the diffusers to floor interaction and the ability of the diffusers/rear wing to interact in essence extending the depth of the diffusers.  

The front is modeled somewhat off of what Pink Panther and other successful MOD cars have done.  I added barge boards mostly for aesthetics, as at 60MPH I doubt the infill and vortex generation will occur or matter much. 

The Formula width chassis within a body give the opportunity to pull the sides way in.   Relocating the radiator to the side and using the existing door edge as a inlet should work nicely.  

Robbie can choose to use any or none of the look.  I just had the model and the wheels started turning.   But I kind of want to see it in real life now.  I think the F-DAT:EVO has to stay though.

Can you send the models?  I might be able to smooth some of it out.

Mr_Asa said:

I like that you've enclosed the engine area.   I'll be interested to see how you access it for maintenance.

Why not seal the rear wheels in?

Dunno yet, so, me too!

For the engine area I would just make the fin/cover removeable as either 1 piece or a few pieces.  You could  also split be body at the doors and just have everything yellow behind the door gap lift off.  You could actually improve the Aesthetic some if you added a line that followed the lower step on the sidepod area.

The model is currently 27 MB.  Its also very hollow and crude (All thin elements).  I will see if I can export it as something smaller for Emailing, or I will put it on my Google Drive and share it.

Pics first, words edited in later...

so, my first reaction is that you probably want to make the raised middle opening have vertical sides to the lower section in front of the tires.  I expect this will be easier to construct, and it would maximize the volume you're feeding into the underbody area.

this side view kinda elaborates most of the feedback I'd have.  I like the barge boards ok-ish; but you really want a vertical panel right behind the wheels (front and rear) if you can.  Most of the LMP cars have moved to this kind of setup, from having a more "open" area behind the wheel, and that's because it's tough to get a flow out from the 'under middle' of the car that can over come the tendency for the flow off the tires to 'wrap up' behind the tire.  So, the vertical panel behind the wheel gives the flow... around the side and/or off the tire... something to "attach to" / "stick to" / "orient to" to encourage it to "move along nicely towards the back".

Similarly, you'll want to extend the 'low down splitter blade' as far back towards the tire that you can.  I've tried to add a vertical rear 'after face' that's minimal and keeping in line with the visual... mounted to a horizontal extension of the diffuser behind the tire.  I've also extended the endplates forward to aid with trying to tie them in for structural reasons.

so, these two I'm trying to outline an idea that (if possible) we try to squeeze in the engine cover behind the driver so there's more of a 'gap' at the body line between the 'angled faces' of the cover and the rollbar.  Then, I'd suggest trying to fill in the triangle of the bar with cheap (free?) insulation and wrapping it in the cheapest r/c aircraft covering you can get.  Or you could probably do the same with dollar store foam board and hot glue.  the benefit of this being improving flow back to the wing.

this back shot is just two suggestions on how you'd probably want to run an 'endplate mount support' off either the frame supporting the diffuser or off the body work.  Between course undulations, aero loads, and the weight of the wing/endplate... I reckon that's more than you want to coordinate a single attachment point to have to handle.

Here's what I currently have the underside set up as.  

I will add changes as Sleepyhead identifies them.  Recognize that much of the shape weirdness is simply trying to make the model quickly to communicate general shapes, and not as plans to build from.   I did not smooth out anything in the cockpit area, or fully enclose it as that would of taken more time.    The ? mark you have indicated is the air intake for the Radiator and general engine air flow as the rest of the car would be enclosed cutting airflow to the engine greatly.  

Also after this one we do the same for the LMP360 K-thanks

Robbie, you still planning on having the hinge setup with this?

In reply to sleepyhead the buffalo :

I will work on adding those tonight.  I like your ideas and wish to subscribe to your newsletter.

nocones said:

Recognize that much of the shape weirdness is simply trying to make the model quickly to communicate general shapes, and not as plans to build from.

The ? mark you have indicated is the air intake for the Radiator and general engine air flow as the rest of the car would be enclosed cutting airflow to the engine greatly. 

Also after this one we do the same for the LMP360 K-thanks

Yeah, I understand.  Hopefully I'm conveying my "broadstrokes" this is why I'm suggesting this.  And yes, that's why I put the "?" there... I suspected that was an intake, but "better to ask".

nocones said:

Also after this one we do the same for the LMP360 K-thanks

Yeah, sure.  I know I made a couple of early comments in your thread, and then kinda "laid off" as you moved off the model and more towards "make the initial big metal pieces" thing.... which effectively what I've done here.  I made a few comments, realized Robbie had a "big bite to chew" just getting this car to Challenge in 2020, and held my mouth shut so he could get it done.  Now, that we're coming back around to a 'second optimization' iteration, I'm being a bit more active.  I'm happy to provide similar to your effort, if/when as you're ready for it.

nocones said:

In reply to sleepyhead the buffalo :

I will work on adding those tonight.  I like your ideas and wish to subscribe to your newsletter.

so, one of the big things that you might have over looked a bit, is that Steve and I were advocating a bit for having a set of tunnels that ran between the body and the formula frame from (at a minimum) the original firewall, all the way back to the end of the body work.  For the autocross, this would probably be fed by either the front splitter, and/or the headlights/turn signals... and it would be "similar" to the Nissan GTR Nismo LM, or whatever it was called.

The, for the drags, the front duct would be "reconfigured" so that the original radiator entrance scoop would feed into those tunnels directly... and effectively we'd reduce the crossectional area by ~50% and Robbie'd probably be able to take off the second element and trim down the wing.  So he'd still have high speed stability/reardownforce... but significantly lower drag.  And, this idea, is uniquely suited both to the Datsun (Datsun-Nissan) and the formula frame inside the car body, setup.

In reply to sleepyhead the buffalo :

I get what your saying about tunnels.  I'll look in his build thread to see what the chassis looked like San's body.  I'm not sure how much space there will be to transition from the area beside the frame to inside of the rear wheels (if that makes sense).  The "Sidepod" can easily be lifted to allow for this tunnel effect and ducting added to the headlights.  I likely won't model that feeder duct but leave that to Robbie.  I can model the changed stepped splitter feeding the tunnels and the area outside of the step being directed to the bargeboards and above the sidepod.  

I'm planning ot update the LMP360 model with the final chassis once it's done.  Then we can start to figure out the Aero.  So far I'm basically planning on making it as close to a Lieger LMP3 car as I can :D

I think I incorporated most of your concerns.  

Also as an aside this is What D/Emod Aero rules should allow.  This car looks amazing and like a spaceship instead of like a doorstop.  

Dude, this is so epic!

Theoretically, would anyone be able to download sketchup and start modifying these files? Did you end up emailing or posting them somewhere? I feel like this might really be my time to start learning stetchup. 

Sleepy - for the 'tunnels' that go on either side of the driver, I was thinking they didnt have to be fully enclosed. Like in nocones drawings, essentially the area outside of the doors but above the floor and below the toneau area would effectively be the tunnel. Does it still work if there isnt an outer wall?

Does that make any sense at all?

I have no insightful bits to contribute, but am here in the role of sponge.

There is so much info here; dispelling some notions as well as confirming some suspicions. Great stuff!

PM'd about the file.  For now I'm not wanting to just put it "Public" but can and will share it with those interested.  

Robbie (Forum Supporter) said:

for the 'tunnels' that go on either side of the driver, I was thinking they didnt have to be fully enclosed. Like in nocones drawings, essentially the area outside of the doors but above the floor and below the toneau area would effectively be the tunnel. Does it still work if there isnt an outer wall?

Does that make any sense at all?

An open sided duct along the sides of the car will have similar effects, BUT the interaction of the front and rear wheels will have a major impact. The basic premise to follow is the closed duct only "sees" the pressure at the entrance and exit. Pressures are the driving force for a component like this. Open sides change that and you effectively have two distinct ducts on each side, with a lot of interaction from other sources.

The LMP cars that start to migrate this way are working within a rule set, one that may be more open than most other motorsports, but a rule set none the less. This car has the opportunity to make the most of not having rules to deal with. 

Also, in my opinion, the car will look more like the original if the sides/door skins are mostly still in place.

Hey, nocones, can I get a "top" view rendering to go with the bottom one you posted today?

Like this?

Its gonna be real difficult to get into that thing.  Its high enough on the sides and far enough in that you can't just step into the seat easily.

Not that that can't be overcome when it reaches reality, just noting what I saw of the car at the Challenge so it is remembered

Mr_Asa said:

Its gonna be real difficult to get into that thing.  Its high enough on the sides and far enough in that you can't just step into the seat easily.

Not that that can't be overcome when it reaches reality, just noting what I saw of the car at the Challenge so it is remembered

I actually have plans for that!

I'm thinking one of the main body supports will come basically from the main roll hoop straight to the door, horizontally. I plan to mark it on top as well with "step" and "not a step" or similar. So a driver would be able to sit on the body on that brace, swing legs over into seat, and then lower I to seat. Removal is reverse of install of something like that.

In reply to Robbie (Forum Supporter) :

Solid.  Make sure to plan for quick egress if need be.

Don't know how I missed this but love where it is going! Hope you have another Zoom meeting.

nocones said:

Like this?

Absolutely Beautiful, thanks!

Robbie (Forum Supporter) said:

Mr_Asa said:

Its gonna be real difficult to get into that thing.  Its high enough on the sides and far enough in that you can't just step into the seat easily.

Not that that can't be overcome when it reaches reality, just noting what I saw of the car at the Challenge so it is remembered

I actually have plans for that!

I'm thinking one of the main body supports will come basically from the main roll hoop straight to the door, horizontally. I plan to mark it on top as well with "step" and "not a step" or similar. So a driver would be able to sit on the body on that brace, swing legs over into seat, and then lower I to seat. Removal is reverse of install of something like that.

That is basically how we handled drivers getting into and out of the open wheel cars. With the extra help that the sidepods usually allowed the driver to get close enough to where they needed to be that they could step into the seat bottom befoe wiggling into place. Similarly, sports racers and cars like that use the method you describe.