sleepyhead the buffalo
sleepyhead the buffalo PowerDork
11/11/23 3:27 p.m.

made it on youtube too

which, I think ended up getting the words you referenced above correctly

preach
preach UltraDork
11/12/23 6:59 a.m.

In reply to sleepyhead the buffalo :

Fantastic!

Congrats again Dan!!!

preach
preach UltraDork
1/13/24 11:43 a.m.
AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
1/13/24 12:18 p.m.

In reply to preach :

Too many N's in UNNACCEPTABLE

nocones
nocones PowerDork
2/18/24 10:32 p.m.

It's almost March.  You know what that means, time for me to try to do everything I should of done all winter in a few short months.  

Before I take the back half of the car completely appart it was time to do some quick mockup work on the direction I'm going to go with the car.   There are going to be some big visual changes that may be unpopular.   

I've slowly been evolving parts of the car from rushed mockup $2000 Challenge car to something more long term.  There will be subtle changes throughout the car but the big changes come at the back.  So step one was to remove all the existing Aero mounts.  

So in an effort to maintain challenge legality I kept as much of the body "OEM" as I could.  The car is basically shaped like an Egg, and in fact some of the Subaru marketing focused on the eggshell imagery for "safety".   Eggs may be a very strong shape but they are not the most aerodynamic.   Rounded at the front is fine, but eventually rounded at the end just results in flow separation, and given the complete lack of flow through my vents, it was pretty obvious that the fenders and greenhouse were experiencing pretty substantial flow separation.  

Flow separation is not good because it makes the wing less effective and most importantly leads to lots of drag.  The car behaved fine at 110mph but the new engine probably will push it up to 130+ which could result in some strong loss of rear down force if the flow is bad enough.  So I need to make the car shapped a bit more like a modern LMP car.  

I was going to mock this change up only in SketchUp, but I honestly wanted to see it "in the flesh" to determine if I would really like it.  Everything is temporary just to really get an idea of the shape.  

I used my favorite tools of Builders board and Hot glue and got to work.   The basic idea is taper the car rather then round the back of it.  Have the taper end abruptly to cause controlled flow separation at the back of the car rather then somewhere along the surface.  

Early effort looked promising so I kept adding board.  It's all just hot glued together and to the car.  

The center only looked pretty good.  It was unplanned but it has a big of a Pagani Zonda look to the way the upper meets the smooth form that makes the bulk of the back. 

Adding the fenders I realized I wanted a bit more height to the middle so I extended that with another piece of board and I had this.  

It will still have a wing so I propped that up just for visual.  

 

I feel like I accidentally went and made it a Ford GT.   But I like it.  It does loose the actual shape of the Subaru 360 a bit but I think it visually works with the rest of the car.  

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
2/18/24 10:43 p.m.

The diffuser looks like your car is E36 M3ting a Batmobile. :-D

nocones
nocones PowerDork
2/18/24 10:45 p.m.

I also wanted to make it all one color.  For one it makes it easier to visualize the lines and the other sometimes things can weight up visually and I didn't want the back to be to heavy looking.  

I think it works really well.  Remember all of this will get reshaped in foam so some of the curves will become a bit more compound and some of the seams and dents will go away but overall the shape looks excellent to me.  

So now who wants to come help me do lots of fiberglass?  I want to make molds of the fenders and remake them entirely of fiberglass and possibly carbon, mostly to remove weight.  The car is substantially rear heavy and when I remake the rear I hope to remove some weight.  The fenders are about 25lbs each so there is opportunity there.  

Piguin
Piguin Reader
2/19/24 5:38 a.m.

Huh, we seem to have a new type of canoe - guess this is what the mods were thinking about with the new edit rule.

 

The car is looking great - yes, it might deviate a bit, but then again it isn't like you could mistake the LMP 360 for a stock Subaru. I like the way it blends, and feels like a natural evolution.

preach
preach UltraDork
2/19/24 6:17 a.m.

I like it, kinda Kammback.

Please put the exhaust out the back panel either in the middle section spread a bit or out the backs of the fenders.

 

TurboFource
TurboFource HalfDork
2/19/24 7:06 a.m.

Looks great!

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
2/19/24 9:10 a.m.

can you route the exhaust to blow the diffuser?

AxeHealey
AxeHealey SuperDork
2/19/24 9:26 a.m.

I saw this on Instagram and have been anxiously awaiting the post here. 

Love it!

2GRX7
2GRX7 Reader
2/19/24 11:44 a.m.

Any concern that those blacked out panels will create too much drag/disruption in the diffuser and wing operation?

sleepyhead the buffalo
sleepyhead the buffalo PowerDork
2/19/24 1:27 p.m.

In reply to 2GRX7 :

My initial impression is that the black in the middle will actually help to cool the engine.  The new bodylines will aid flow to the rear wing, and the low pressure from the rear foil's downforce will help pull air out from the engine bay.

In reply to nocones :

you mentioned (offline) thinking about moving to swan necks, that are 20inches apart, based on the chassis structure.  Does that end up in about the place these orange lines are:

if so, I'd suggest that the rear middle section be "flat" between those mounts, and then have the curve outboard of them.  that way there's no acute angle between the body and those mounts... which has some drag benefit.  alternatively, I might suggest you hold off on making the fenders, in case you decide to push the mounts out to here:

and there'd be a similar suggestion to square off the inside face of the fender and have the swan mount be just outboard of the inside face of the fender.  I can see pros/cons to both setups... and I recall design language for both setups in past LMP cars... which also tend to have some gridding at the back end of those fenders to extract/straighten the flow out of the tires "up".

nocones
nocones PowerDork
2/19/24 1:53 p.m.

In reply to sleepyhead the buffalo :

Yes the orange is approximately where the chassis rails are.  That is the easiest place to get strenght for the wing to push on.

I hadn't fully considered your second suggestion.  The structure would have to be more remote from the chassis so it may wind up overall heavier.  That said it would be easy to make the supports bolt in from the side and be easy to remove.  I suspect there isn't a clear winner from an Aero perspective just roughly equivalent tradeoofs.  

Wing support wise I don't think there would be much difference in required internal structure.  If the mounts where narrow I would have ~24" of unsuported outboard wing, and with wider mounts the center span would be about 48".  The spar would be a bit smaller but not dramatically.  

I will annoy you more for sure once all this starts to become real stuff.  It will be a bit before concept becomes reality as this weekend the motor swap starts in earnest.

sleepyhead the buffalo
sleepyhead the buffalo PowerDork
2/20/24 11:01 a.m.
nocones said:

In reply to sleepyhead the buffalo :

Yes the orange is approximately where the chassis rails are.  That is the easiest place to get strenght for the wing to push on.

I hadn't fully considered your second suggestion.  The structure would have to be more remote from the chassis so it may wind up overall heavier.  That said it would be easy to make the supports bolt in from the side and be easy to remove.  I suspect there isn't a clear winner from an Aero perspective just roughly equivalent tradeoofs.  

Wing support wise I don't think there would be much difference in required internal structure.  If the mounts where narrow I would have ~24" of unsuported outboard wing, and with wider mounts the center span would be about 48".  The spar would be a bit smaller but not dramatically.  

I will annoy you more for sure once all this starts to become real stuff.  It will be a bit before concept becomes reality as this weekend the motor swap starts in earnest.

yeah, it might be a wash... structurally; I wasn't sure how strong those angled supports were that were going from the bottom center of the chassis up to support the top body cross-rail.  the closer center mounts will be there will be less disrupted flow at the tips... although that'll be reduced anyhow with the use of swan necks instead of under-wing mounts.  off hand, I think the biggest benefit will be that more of the upright will be "hidden" from creating drag by being inside the fender... than it would be in the middle.

along the lines of "no aero rules"/"reduce drag"... I'm not sure how bad rear brake cooling has been, but spatting the way I'm about the suggest probably means you want to force some cooling air into the rotors... which could be easily picked up from the front of the rear fenders...

MNIMWIUTBAS
MNIMWIUTBAS New Reader
2/20/24 4:44 p.m.

I don't know if the airflow is attached enough for this to be much of a factor but it's something to consider.

 

Full slides here http://www.grandmarq.net/blaze/Blaze_Pics/AE%20507%20lect%207%20Aero%20Drag%20of%20Autos.pdf

2GRX7
2GRX7 Reader
2/21/24 11:46 a.m.

 

I'm not sure if you've placed the wing there just for a visual mock-up, or if it's going to mount in the that exact location, but consider either moving that wing forward of the engine bay/wheel well openings as you'll allow that rear wing to utilize the laminar flow from your reworking of the body, plus, it could create low-pressure suction to draw air out of the engine compartment. If left that far back, you'll no only run into the energized, high-pressure air of the wheel-well, you'll run into the drag-inducing engine compartment (are you directing high-pressure air into the front of the engine bay?) wreaking havoc on wing efficiency.   

 The low pressure zone between the engine compartment and the well would also benefit from a spoiler, possibly helping diffuser efficiency.

Don't take my word for it-my info's from my work with ALMS 20 years ago, but you can pretty much look at any LMP1 from the last two decades. None of them have wings extending past the bodywork-unless its' name is Peugeot, and that's not really a wing!

Purple Frog (Forum Supporter)
Purple Frog (Forum Supporter) Dork
2/21/24 12:39 p.m.

I didn't sleep in a Holiday Inn last night... not an aero expert.   But, from my research I'm wondering if the upturn angle of the diffuser is a bit too steep.   I was told ~15 degrees was max to prevent separation.  I was just wondering if that bell design is too large for the HP/weight/size of the Subie.  I know on my previous 140 mph cars we had smaller units that generated a lot of downforce... so much we could reduce wing sizes.

Not attacking, just asking.

Gzwg
Gzwg New Reader
2/22/24 2:51 a.m.

I'm in no way experienced with any aero, but I would hate to see you doing lots of fibreglass work without having at least an idea of the results.

Wouldn't it make sense to model it in CAD and run a Test? Superfastmatt shows a nice website in his episodes for the landspeed car.

I'm pretty sure this will not be 100% accurate, but just to get a comparison between the two versions it could help?

 

But looking at all the help you have available, I'm sure this is nothing new to you smiley

 

Beside that - I love that car!

sleepyhead the buffalo
sleepyhead the buffalo PowerDork
2/22/24 2:09 p.m.
Gzwg said:

Wouldn't it make sense to model it in CAD and run a Test? Superfastmatt shows a nice website in his episodes for the landspeed car.

I'm pretty sure this will not be 100% accurate, but just to get a comparison between the two versions it could help?

That was AirShaper, which has a "try out a run for $50", otherwise it's $1k to setup with a 25 simulations / year limit on their "Discovery" lowest tier.

I've also heard recently of SimScale, which has a "Community" tier that is free for "10 unrestricted simulations", so long as the model isn't too detailed (i.e. limited to "3000 core hours", which afaik is a processing time limitation).  Unfortunately, there's nothing public on their pricing for a "professional" single seat tier.

I have not used either, and expect it'd take some time for me to get up to speed on using either.

nocones
nocones PowerDork
2/22/24 2:21 p.m.

In reply to sleepyhead the buffalo :

Now I wonder if Airshaper would want some silly flow map graphics with a pretty interesting looking budget oriented race car..  

I've looked a little and yeah the cost to do something real just gets very spendy very quickly and based on my FEA experience the skill and effort required to prevent Garbage In from occuring and ensuring you get Garbage Out very high.  

But I would consider it if someone wanted to spearhead that effort on the cars behalf. 

TurboFource
TurboFource HalfDork
2/22/24 3:22 p.m.

Nocones, , is the builder board stiff enough to put a layer of fiberglass on?

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
2/23/24 10:25 a.m.

In reply to sleepyhead the buffalo :

"a car is neither spherical nor rotating, unless you've really messed up."

Gzwg
Gzwg New Reader
2/26/24 3:07 a.m.

One more thing that goes through my Head:

Your Windscreen is quite upright. How much disturbed air does it create, and is it maybe worse enough that it does not really matter what you do at the back of the car?

Would some kind of small deflector before the screen help with that?

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