Subaru Impreza Pikes Peak

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MadMatt
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Re: Subaru Impreza Pikes Peak

Post by MadMatt » Tue Jun 04, 2013 11:59 am

jamsbong wrote:Sounds like you have a tight schedule. Well good luck with the project! Be sure to update your blog when you can. :D
Cheers for the support mate, yes it is really tight. I even planned to do a RP of one of the model and test it in the wind tunnel (1/10 scale) but I am afraid that I won't have time. Who knows but it is really tight.

Do not hesitate to post your comment on the project, again I am not an aerodynamicist so I might do some mistakes :)

jamsbong
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Re: Subaru Impreza Pikes Peak

Post by jamsbong » Tue Jun 04, 2013 2:23 pm

Just focus on getting those scheduled work done first. After you show us the results, i think we can discuss more about it.

MadMatt
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Re: Subaru Impreza Pikes Peak

Post by MadMatt » Wed Jun 12, 2013 12:31 pm

Finally the Pikes Peak "v1" is presented!

Image
Yes! It is now time to present the 3D model of the car I have designed. It is the first version, which implicates that there will be devices added or changed, modified, and so on, to meet the objectives that I specified some time ago. I must also repeat that I have taken the WRC version as a base car (which I presented already as well). My job here was to create this parts and assemble them on the car. All the modifications done are not affecting the chassis structure so they can be added or removed easily (this is also valid for real life).

As you can see, it has got a fairly large rear wing assembly consisting of a main element on top with a flap over it, and a lower element. The planes are connected through very large end plates and fixed to the car by 4 swan-type mounts to ensure the downforce produced does not break them. The diffuser is divided into a large central section that starts at about the rear wheel axis and expends nicely up, and a smaller section behind the wheels where extra flaps helps to use this “lost” area efficiently. We can also slightly see the (blue) radiator in the boot with its opening.

Moving to the side now, we see the cut in the rear door to feed the radiator with air, and a small wing below it to help guiding the air inside. The splitter end plates extend quite far back (over the front wheel) and far in upfront as well to use the air stagnation there at the maximum. We also see that the car is sitting lower (80[mm] actually) than the WRC version, as the Pikes Peak race is now fully asphalted. The rear tyres width has been increased by 50[mm] and the rear arches extended accordingly!

Finally, a front view of the car with its sister car on the left, showing that the engine cooling has been enhanced and that winglets have been added to the side of the front splitter end plates. Under this splitter are diffusers (that I will show in the next update), but you already get the idea.

Again, this is the “v1″, so after the aerodynamic simulations, parts will be changed to enhance the performance of the car, but to be honest I have already conducted quick calibrating simulation, and results looks already very very promising, but I will not say too much for now!
>> HERE! <<

:)

Blanchimont
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Re: Subaru Impreza Pikes Peak

Post by Blanchimont » Wed Jun 12, 2013 12:58 pm

It looks great!

Are you planning to simulate the different versions of the car through a laptime simulator like virtual stopwatch ( http://www.competition-car-engineering.com/ ) or optimumlap ( http://www.optimumg.com/software/optimumlap/ ) to get some numbers on how effective your aero upgrades are for a given track?

For me that would be the next logical step after calculating cd and cl numbers by CFD.
Dear FIA, if you read this, please pm me for a redesign of the Technical Regulations to avoid finger nose shapes for 2016! :-)

MadMatt
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Re: Subaru Impreza Pikes Peak

Post by MadMatt » Wed Jun 12, 2013 1:03 pm

Blanchimont wrote:It looks great!

Are you planning to simulate the different versions of the car through a laptime simulator like virtual stopwatch ( http://www.competition-car-engineering.com/ ) or optimumlap ( http://www.optimumg.com/software/optimumlap/ ) to get some numbers on how effective your aero upgrades are for a given track?

For me that would be the next logical step after calculating cd and cl numbers by CFD.
Thanks!

I made myself a simulator in MATLAB that I will maybe use (if I have time at the end), but it is all steady state. Ultimately it would be great to have the Pikes Peak race course with elevation modeled but that would be a project in itself. The problem with simulating the car on a "random" track is that it completely depend on the gear ratio and the track for example! I would have to find a track that is very close to Pikes Peak in order to make this useful so I don't know if this is relevant. I don't know if I have explained well.

But that's an option, for sure! :)

variante
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Re: Subaru Impreza Pikes Peak

Post by variante » Wed Jun 12, 2013 1:17 pm

Good start!
I guess, just looking at it, you're not far from your target.
But why don't you attach those pylons, the four mounts i mean, to the beam wing? Structural reasons?
Also, if i were you, i would work a lot with that beam wing (looks like it will almost produce lift with that AoA), especially considering the help it could give to extract air from the diffuser.
You might want to consider vortex generators on the roof as well.

Great project BTW

Blanchimont
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Re: Subaru Impreza Pikes Peak

Post by Blanchimont » Wed Jun 12, 2013 1:19 pm

I forgot to mention that optimumlap is freeware and you can create your own simple tracks with this software.

Although i don't know how accurate it is, it is great to change certain parameters and get nice plots from the changes.
The plot is a surface that represents the lap time dependent from two variables (power, downforce, drag, weight,...).

You should at least have a quick look over the software, i would say!
Dear FIA, if you read this, please pm me for a redesign of the Technical Regulations to avoid finger nose shapes for 2016! :-)

Alonso Fan
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Re: Subaru Impreza Pikes Peak

Post by Alonso Fan » Wed Jun 12, 2013 1:21 pm

looks good! :D

the only thing i'm concerned about is that the front wing has two large fins attached to the body of the car. this, theoretically wouldn't allow air hitting the front bumper to spill out around the car, and thus, would create vast amounts of drag, as the air has nowhere to go except hit the bumper head on. i would advise making it so that the front wing creates downforce, and guides air to that magnificent rear wing you have there. i know its only v1, so this is just some advice for your next version

love the rear wing btw :D

i don't mean to say the body kit is bad, its still a very good attempt, much better than i could do myself
MVRC - SHM Racing

MadMatt
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Re: Subaru Impreza Pikes Peak

Post by MadMatt » Wed Jun 12, 2013 1:36 pm

variante wrote:Good start!
I guess, just looking at it, you're not far from your target.
But why don't you attach those pylons, the four mounts i mean, to the beam wing? Structural reasons?
Also, if i were you, i would work a lot with that beam wing (looks like it will almost produce lift with that AoA), especially considering the help it could give to extract air from the diffuser.
You might want to consider vortex generators on the roof as well.

Great project BTW
Thanks!

I think that the end plates will be enough to hold the beam wing, so I don't have these huge mounts going all the way down. You are absolutely right with the beam position, I will it will be very interesting to vary (height and longitudinal position), considering I also have the radiator flow to pump (and the diffuser as you said). But it produces downforce (roughly 20% of the whole wing assembly) already.

Vortex generators are already to be implemented in future versions, but I first really have to look carefully how the flow is so I can place them efficiently! :)
Blanchimont wrote:I forgot to mention that optimumlap is freeware and you can create your own simple tracks with this software.

Although i don't know how accurate it is, it is great to change certain parameters and get nice plots from the changes.
The plot is a surface that represents the lap time dependent from two variables (power, downforce, drag, weight,...).

You should at least have a quick look over the software, i would say!
Then it makes sense! Yes why not that sounds really good, I will have a look at that and hopefully can manage something. :)
Alonso Fan wrote:looks good! :D

the only thing i'm concerned about is that the front wing has two large fins attached to the body of the car. this, theoretically wouldn't allow air hitting the front bumper to spill out around the car, and thus, would create vast amounts of drag, as the air has nowhere to go except hit the bumper head on. i would advise making it so that the front wing creates downforce, and guides air to that magnificent rear wing you have there. i know its only v1, so this is just some advice for your next version

love the rear wing btw :D

i don't mean to say the body kit is bad, its still a very good attempt, much better than i could do myself
Your point makes sense! Yes it creates a high amount of drag, so maybe I will cut a bit the end plate like they are doing on F1 front wings endplates. That's definitely an area that needs work there! I value all points of views, good or bad ones, you learn from everything so I'm happy people post their views on that, don't worry! There is so much to do on an "unlimited" car that it is sometimes difficult to keep feets on the ground.

:)

wesley123
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Re: Subaru Impreza Pikes Peak

Post by wesley123 » Wed Jun 12, 2013 1:44 pm

Alonso Fan wrote:
the only thing i'm concerned about is that the front wing has two large fins attached to the body of the car. this, theoretically wouldn't allow air hitting the front bumper to spill out around the car, and thus, would create vast amounts of drag, as the air has nowhere to go except hit the bumper head on.
That's the whole point of the end plate fences, trapping the air, creating high pressure over the splitter. That's simply how the splitter works. And yes, it adds drag, however I doubt it would be more draggy than a front wing, and if it is, it also generates more downforce. Also, there is (virtual) power to turn into downforce, so drag isnt that big of a problem.
"Bite my shiny metal ass" - Bender

variante
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Re: Subaru Impreza Pikes Peak

Post by variante » Wed Jun 12, 2013 2:42 pm

MadMatt wrote:I think that the end plates will be enough to hold the beam wing, so I don't have these huge mounts going all the way down.
I didn't explain my point very well, i'll be more precise:
in this configuration the car has 4 pylons placed in a sensible position, thus creating a good amount of drag and disturbing the flow to the rear wing. Moreover you have 2 endplates, which are supposed to be thick enough to firmly hold the beam wing. This means a total of 6 thick elements hitting fast moving air with consequences that you can imagine.

My proposal is to get rid of 2 pylons from the main wing, and instead of those, placing 2 pylons on the beam wing (linking the beam wing to the radiator outlet: a non sensible area.
With this solution you could drastically reduce the thickness of the endplates, which wouldn't be structural elements anymore.
Doing so you would have only 2 thick elements hitting fast moving air.

MadMatt
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Re: Subaru Impreza Pikes Peak

Post by MadMatt » Wed Jun 12, 2013 3:03 pm

variante wrote:
MadMatt wrote:I think that the end plates will be enough to hold the beam wing, so I don't have these huge mounts going all the way down.
I didn't explain my point very well, i'll be more precise:
in this configuration the car has 4 pylons placed in a sensible position, thus creating a good amount of drag and disturbing the flow to the rear wing. Moreover you have 2 endplates, which are supposed to be thick enough to firmly hold the beam wing. This means a total of 6 thick elements hitting fast moving air with consequences that you can imagine.

My proposal is to get rid of 2 pylons from the main wing, and instead of those, placing 2 pylons on the beam wing (linking the beam wing to the radiator outlet: a non sensible area.
With this solution you could drastically reduce the thickness of the endplates, which wouldn't be structural elements anymore.
Doing so you would have only 2 thick elements hitting fast moving air.
Ah yes I see now! I already thought about it but I couldn't come up with an elegant design. I might think about it again tho, but since I have these mounts, I recon they are kind of an "unique" feature which will make the car more recognizable. I won't sacrifice performance on behalf of design, but at the moment I will keep this design. It is quite tricky to make such a huge assembly look good with the rest of the car! :)

Alonso Fan
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Re: Subaru Impreza Pikes Peak

Post by Alonso Fan » Wed Jun 12, 2013 3:34 pm

wesley123 wrote:
That's the whole point of the end plate fences, trapping the air, creating high pressure over the splitter. That's simply how the splitter works. And yes, it adds drag, however I doubt it would be more draggy than a front wing, and if it is, it also generates more downforce. Also, there is (virtual) power to turn into downforce, so drag isnt that big of a problem.
your point also makes sense! :D

i was just trying to find other ways of using the air. as MadMat said, making slots in the front wing end plates would allow sufficient air to the rear wing.

just trying to help
MVRC - SHM Racing

wesley123
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Re: Subaru Impreza Pikes Peak

Post by wesley123 » Wed Jun 12, 2013 4:38 pm

Alonso Fan wrote:
wesley123 wrote:
That's the whole point of the end plate fences, trapping the air, creating high pressure over the splitter. That's simply how the splitter works. And yes, it adds drag, however I doubt it would be more draggy than a front wing, and if it is, it also generates more downforce. Also, there is (virtual) power to turn into downforce, so drag isnt that big of a problem.
i was just trying to find other ways of using the air. as MadMat said, making slots in the front wing end plates would allow sufficient air to the rear wing.
Slots in the end plate wouldnt allow more air to the rear wing. Why? This is based on a normal street car(although stripped down), This street car houses more passengers and luxury stuff. It isnt a f1 car or an LMP. In those cases, air to the side of the car would indeed help. Here, not so much.

The air would flow around the side(and not being aided by the wheels) into the duct, and if it doesnt flow in the duct, it would fill in behind the car, then indeed in between the rear wing tiers.

However, over the car you have huge unobstructed area of bodywork where the air can flow over freely, and then flow to the rear wing, and actually fully hitting the wing, instead of filling in the area behind the tiers. So unlike F1 cars(and in a decent amount LMP's) air around the car isnt the better solution, and that gets worse with cooling ducts in the side of the car.

So therefore, together with the splitter end plates, I feel that airflow over the car is a much, much better solution than around it.
"Bite my shiny metal ass" - Bender

Pierce89
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Re: Subaru Impreza Pikes Peak

Post by Pierce89 » Wed Jun 12, 2013 5:52 pm

My suggestions:
1. Start your rear diffuser farther forward
2. Add a front diffuser vented behind the front wheels
3. Find a better method of attaching rear wing assembly( maybe two centered swanneck mounts and to attachments to the endplates. Also maybe move whole assembly just slightly forward so the mounting isn't so stressed and difficult to work with.
4.On the front endplate wings, are they three stacked wings or a traditional three element wing? I'd go with the latter.
5. Ignore anyone talking about drag. I'm sure you've noticed that other Unlimited cars for Pikes Peak ignore drag. If they think there's too much drag, they just add power.
6. Start working on fine geometry refinement rather than macro changes. There's a huge amount of DF in detail refinement.

I would definitely add a front diffuser.
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