Official "my latest HPDE experience" thread.

[v67gsr]

Originally Posted by 320icar

its not bolted to the trunk lid. do you have any idea how miatas mount their GT and track wings.

May be.

But I sure know these.

https://scontent-sea.xx.fbcdn.net/hp...b9&oe=55D9D86F
https://scontent-sea.xx.fbcdn.net/hp...9e&oe=55E1139B
https://scontent-sea.xx.fbcdn.net/hp...05&oe=55D4D7A3
https://scontent-sea.xx.fbcdn.net/hp...2d&oe=55D51B24

[dared3vil0]

Anyone else going to ORP May 31st?

[320icar]

Originally Posted by v67gsr

May be.

But I sure know these.

MX-5 Miata Forum
MX-5 Miata Forum
MX-5 Miata Forum
MX-5 Miata Forum

Sorry bruh. I'm a cr.net user, not an m.net guy so I can't view it

[v67gsr]

Originally Posted by 320icar

Sorry bruh. I'm a cr.net user, not an m.net guy so I can't view it

My bad. Try again.

[320icar]

Definitely has the classic chikara look

[SumAznGuy]

How much added weight is there with all that aero V67?

Time to man up and make it out of carbon fiber.

[Deepstriker]

Originally Posted by v67gsr

Your pizza example does not resemble what is happening to the mounting location. Do some study before you start arguing. I am no engineer but I do know a bit about aero because I paid a lot of attention in this topic in the past 7 years. I hate to say this but the way you do your aero resemble a lot of ricer and time attack wannbe. Do yourself a favor, redesign it, don’t be a joke and a ticking time bomb moving around town. Last thing we want is someone head got chopped off because you refused to accept some basic physic.

Oh, my apologies I didn't mean to offend you. Although I don't think we were really arguing since I approached you with a question - which is still left unanswered by the way.

Will the wing hold up the 80 pizza load or not?

I spoke to the driver and he said that he used three 5/16" Grade 8 SAE bolts on each side of the stand. I did some quick calculations and using a safety factor of two, each of those bolts can withstand 3490lbf. Combined strength of 10,470lbf to shear all 3 at once, but of course in reality the bolt closest to the front of the car should shear first.

I would be surprised if his wing is really making that much downforce to create that much force in single shear loads even with a moment about the furthest mounting point. I'm curious if you see something wrong with this calculation. I could provide you with an FEA simulation if needed to show you how I have simulated his wing. It was really bothering me that you seemed alarmed that his wing would fly off so I had to be sure this wouldn't be the case if we ran at the same trackday. Safety first!

The driver did have one comment to make though which was that the car attended the track day and drove home perfectly fine with the wing still attached. The driver also couldn't say the same for you making it home in one piece either though:



After the Driver sent me the photo I noticed that the wing was mounted to the trunk and not chassis mounted either, isn't that more double fail than his setup?!

[v67gsr]

Originally Posted by SumAznGuy

How much added weight is there with all that aero V67?

Time to man up and make it out of carbon fiber.

I picked a thicker aluminum sheet for safety reason and therefore they are fairly heavy. The whole package weight approx 60lb (front splitter, flat under tray, rear diffuser). Phase two design will feature thinner aluminum and CFRP. Should be able to cut the weight by 15 lb. Good thing is most of the weight are below roll center so it won’t impact the handling much.

Carbon fiber is too dangerous and costly to use on those parts. I want material that is cheap, easy to replicate, but still be able withstand impact from flying debris. ABS plastic and aluminum are the best options.

[duy-]

nathan looks like hes been working out, makes it funnier that hes the only one not pushing

[SumAznGuy]

Originally Posted by Deepstriker

I would be surprised if his wing is really making that much downforce to create that much force in single shear loads even with a moment about the furthest mounting point.

The weakest part isn't the bolts but the trunk itself if the trunk lid hasn't been reinforced.

Hence V67's comment about how/where the wing is attatched to.

[v67gsr]

Originally Posted by Deepstriker

Oh, my apologies I didn't mean to offend you. Although I don't think we were really arguing since I approached you with a question - which is still left unanswered by the way.

Will the wing hold up the 80 pizza load or not?

I spoke to the driver and he said that he used three 5/16" Grade 8 SAE bolts on each side of the stand. I did some quick calculations and using a safety factor of two, each of those bolts can withstand 3490lbf. Combined strength of 10,470lbf to shear all 3 at once, but of course in reality the bolt closest to the front of the car should shear first.

I would be surprised if his wing is really making that much downforce to create that much force in single shear loads even with a moment about the furthest mounting point. I'm curious if you see something wrong with this calculation. I could provide you with an FEA simulation if needed to show you how I have simulated his wing. It was really bothering me that you seemed alarmed that his wing would fly off so I had to be sure this wouldn't be the case if we ran at the same trackday. Safety first!

The driver did have one comment to make though which was that the car attended the track day and drove home perfectly fine with the wing still attached. The driver also couldn't say the same for you making it home in one piece either though:



After the Driver sent me the photo I noticed that the wing was mounted to the trunk and not chassis mounted either, isn't that more double fail than his setup?!

Once again, if you are so proud of what you have created, why not publicly admit that this is your OWN car. You did not speak to the driver. You ARE the driver, the owner, the one who make this wing mount. Although we never meet in person but you should know better that I am within the local track runner circle you hang out with and I have intel of what is happening. Don’t pretend to be the “driver” or “owner” anymore.

You talk about load on the bolts. Have you forgotten there are more than just bolts? Did your simulation factor in the mounting area structural strength? Down force and backward drag load which increase exponentially as speed increase? How about the leverage ratio that will multiply the amount of load and the leverage point factor that will alter the direction of load apply to the different mounting points? Form the number you provide, I don’t think you have consider those factors. Aero is more than just single direction load on single object. You can have bolts made out of adamantium or vibranium but if the surface you mounted to is weak, the aero will still fail at speed. Simple physic. I have my share of aero failure and I almost killed myself. I was as naives as you are today thinking the mountings and bolts that I used to bolt the splitter to the front lip were strong enough and paid no attention to the mountings of the lip itself. Result was half of the front lip got torn off by the down force generated by the splitter. It happened just before turn 1 on Pacific. I was lucky to walk away without any dent on my car and myself. I don’t want the same happen to anyone playing with aero.

You got me on the not able to drive home in once piece. Although 2.5 engine swap was planned for 2014, blowing up my 2.0 was not part of the plan. It ended my 2013 season earlier than I would like.

[smoothie.]

I.. I'm just here to learn about track days.

[Expresso]

Originally Posted by smoothie.

I.. I'm just here to learn about track days.

Now you're learning about downforce and pizza loads!

[trollguy]

anyone else hungry? deepstriker can you pls deliver 80 peeezas on your wing

[dared3vil0]

Just start an aero thread...

[trollguy]

actually this thread is also about accounting!

DEFINITION of 'Leverage Ratio'

Companies rely on a mixture of owners' equity and debt to finance their operations. A leverage ratio is any one of several financial measurements that look at how much capital comes in the form of debt (loans), or assesses the ability of a company to meet financial obligations.



Read more: Leverage Ratio Definition | Investopedia
Follow us: @Investopedia on Twitter

[trollguy]

and it occurred to me (not singling anyone out but just for internets sakes), engineering is an easy subject to debate.

using keywords such as: force, area, tension, structural, and load - you can debate.

ie:

hey guys, i was thinking about buying a BOV from HKS for my car but had a few questions. does the BOV decrease engine load? i'm worried about the extra sheer force it creates.

or in this case regarding aero:

i dont think your canards are very effective at increasing down force to the surface area where it's mounted. in addition, the structural integrity of the mounting hardware of the candards are likely going to be an issue.

[Expresso]

Originally Posted by trollguy

and it occurred to me (not singling anyone out but just for internets sakes), engineering is an easy subject to debate.

using keywords such as: force, area, tension, structural, and load - you can debate.

These keywords can also be applied to Porn.

[trollguy]

he was pounding with so much force that he had to release his tension. he blew his load all over her chest area.

you are onto something.

[bcrdukes]

Originally Posted by Expresso

Now you're learning about downforce and pizza loads!

Originally Posted by trollguy

anyone else hungry? deepstriker can you pls deliver 80 peeezas on your wing

I hope you Internet geeks know that when you shove pizzas down that hole in your face, you add weight to the driver, right? And when the driver suffers from thirst while behind the wheel, naturally he/she will drink water, which further expands the dough in the stomach, adding even MORE weight to the vehicle, which then throws off aerodynamics and the corner balance of the vehicle's suspension.

[Deepstriker]

Originally Posted by v67gsr

You talk about load on the bolts. Have you forgotten there are more than just bolts? Did your simulation factor in the mounting area structural strength? Down force and backward drag load which increase exponentially as speed increase? How about the leverage ratio that will multiply the amount of load and the leverage point factor that will alter the direction of load apply to the different mounting points? Form the number you provide, I don’t think you have consider those factors. Aero is more than just single direction load on single object. You can have bolts made out of adamantium or vibranium but if the surface you mounted to is weak, the aero will still fail at speed. Simple physic. I have my share of aero failure and I almost killed myself. I was as naives as you are today thinking the mountings and bolts that I used to bolt the splitter to the front lip were strong enough and paid no attention to the mountings of the lip itself. Result was half of the front lip got torn off by the down force generated by the splitter. It happened just before turn 1 on Pacific. I was lucky to walk away without any dent on my car and myself. I don’t want the same happen to anyone playing with aero.

So, I spoke to the Driver just now to address your concerns.

He still would like to see an answer, whether or not his wing will hold up ALL 80 pizzas or not.

The driver would like to comment that while your concerns may be borderline legitimate, you still make a huge assumption that he has not factored in these considerations in his design. For starters his wing is not a high camber wing, L/D ratio is quite low. Based on one picture he felt slightly offended that you were able to determine so many things regarding his design yet did not address your own wing being mounted on your trunk. The hypocrisy makes him feel like he should no longer listen to you.

However he took the time out of his lunch break today to type out this response:

"V67-GSR's concerns are all based on theory and I doubt he has calculated anything for his own designs seeing as he thought bolting a splitter to a front lip would hold up. It's kind of funny how you think that we are the same person.

For starters I don't think he understands what a Newton or a Pound is and how that even translates to strength of materials for what I'm using. Based on his leverage ratio analogy I believe he is more well versed in the field of accounting than engineering.

I saw your post regarding the grade strength of the bolts and how my wing would create a moment based on the way it's mounted and I'm glad you ran the math as well.

It seems like V67-GSR doesn't have a clue what a moment is or anything engineering related since he seems to like to repeat the same thing you had commented earlier but worded it as a question. He seems to think FEA simulations can only be done on single objects, I'm glad you loaded up ANSYS to do your simulations as that can take some time out of your work day to do.

Some people are clueless I say, clueless."

[Matsuda]

I think we should just end this discussion on the note that I would like to train a cat to drive a miata

[v67gsr]

Originally Posted by trollguy

i dont think your canards are very effective at increasing down force to the surface area where it's mounted. in addition, the structural integrity of the mounting hardware of the candards are likely going to be an issue.

It was a proof of concept and second choice for that area. First choice has clearance issue under heavy braking and turn in and I have to drop that concept. Those canards will be replaced with 3D printing parts, and/or side extension like on Austin and Jacky’s car.

[belaud]

Originally Posted by Matsuda

I think we should just end this discussion on the note that I would like to train a cat to drive a miata

[dared3vil0]