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Discussion in 'The Garage' started by satyajitmenon, Nov 3, 2012.
Chris Harris drives the DeltaWing @ Road Atlanta...
Technical discussion starts @ 6:35
Wow fantastic video. They need stuff like this to recruit highschool kids for engineering.
Moral of the story: everything should look like male genitalia.
I ate crow on that car. When I first saw a pic of it some time ago, I laughed out loud. Then, I read an article in C&D that explained who came up with it, and some big names in racing wanted to see it built and raced.
that's awesome. i wish they WOULD do a 50-minute episode to discuss all the technical details of the car. very interesting.
i need to find a way to get involved with a race team
That was awesome, I think everyone would love to hear more from the guy Chris Harris talks to at the end.
Was that the designer?
Could someone possibly give me a cliff notes version of why they made the wheels so close together at the front? Is there some kinda basic science I'm missing? 'Cause I can't fathom how/why that strange setup could make a positive difference in handling.
Not shitting on it, I just...don't understand.
edit: I get the premise, kind of; the 'balance' aspect. All the weight in the back, so the front can be small...but what makes the steering actually...work? Does a narrow front track width actually increase responsiveness/turning ability?
Were those 90's Pontiac commercials lying to me?
Seems like it, the inside tire during cornering has a very small contact patch since all the weight goes on the outside tire. With a narrow track there simply is enough weight transfer so both tires have a similar contact patch.
I guess I get that part...it's just that you think you comprehend suspension dynamics fairly well...then you listen to that guy talk.
What the hell are 'roll' and 'heave,' anyway? I mean, I know 'roll' in the traditional sense, but it sounds more like he's describing jounce and rebound or something. Damn Brits.
He explicitly makes motions to illustrate what roll and heave are.
He really doesn't.
Since I don't speak the queen's English, I googled it and looked around. Best I can tell, by heave he's describing both jounce and rebound (upward and downward movement of the car/compression and decompression of the suspension).
Roll should be universal, but he somehow made it not.
For probably being a certifiable genius, he sure is a limey 'tard.
You're a hoot at parties, I bet.
I love road Atlanta, hell of a fun track to go around too! Did not realize it put more loads than LeMans, guess it makes a bit of sense with all the hills. Going hard down the back straight, downhill, braking hard to get into the turn....yeah that'll make ya pucker if you're not use to it, lol.
front end suspension is nuts how tiny it is. FSAE Shocks maybe?
I read an article in Pop Sci about this baby, and it shed some light on some of the design reasons behind why the DeltaWing looks and behaves the way it does.
To answer the question about what Ben was explaining as to why it can still corner, it has to do with the following:
Consider this. Have you ever watched Alonso throw his F1 cars into corners? If so, then perhaps you will see where I am going with this. Whenever a car turns, there is a weight transfer towards the outward side of the vehicle. For vehicles with 4 wheels, the majority of the weight will be supported with the outer front tire and the outer rear tire. Conversely, the inside wheels will be carrying minimal load. This is why cars flip over if they try to turn at high enough speeds without a significant amount of force keeping them glued to the ground. The DeltaWing has its front wheels close to each other, which ensures that even if there is a load transfer, because the wheels are so close, the difference in load between the two wheels would be kept low. Couple this with the fact that the Wing's rear end is highly stable and you realize that there is no way in hell that the front end would ever come off the ground. In addition, the majority of the mass of the vehicle is in the rear, and when combined with a long nose (Yes, I get it. It looks like a penis), the result is akin to turning a sledgehammer. Trying to turn a sledgehammer by swinging it is difficult but if you lay it flat on a table and push the handle, you will find that it rotates extremely easily. That push on the handle is the same as the turning force generated by the front wheels. Now you see that it takes not a whole lot of effort to get the vehicle moving in any direction you'd like, and this is what Ben was talking about when he said the front tires are used very efficiently. The front tires job in the Wing is mostly turning since the rear does most of the braking).
As for "heave" and "roll", think of a ship out in water. Heaving is the up and down motion of the boat, while roll is the side to side motion (which makes people sea sick). In describing rear suspension of the Wing, Ben states that the damping in the heave direction (up and down) is typical of race cars but the damping in the roll direction (side to side) is much stiffer since the rear does most of the supporting of the vehicle (in both weight and in keeping the car from flipping over). That's why he mentioned the whole "monkey motion" portion of the rear suspension; it's a peculiar set up that allows the vehicle to use a conventional shock and spring to control heave but to use a stiff bar to control roll.
I can upload the images of the Pop Sci article if you guys want to give it a read. It goes over how Ben started with the idea and explains some of the reasoning behind the design.
Apparently, Porsches don't like DeltaWings.
Toyotas don't either.
I wonder how much truth there is in the claims that the smaller frontal area makes it hard to see the Delta Wing... Especially sitting in a race car where side visibility is pretty poor to start with.
Maybe they should paint the delta wing some color other than black? Even though I think it would look awesome in matt black/grey, like an SR71 or something.
Haha, I laughed when I saw that first vid.
But in all seriousness, the lack of downforce on the DeltaWing's front end combined with its lightness makes it really easy to throw it off course. That, combined with how it lacks any roll resistance up front, makes it almost impossible to recover from a crash.
Probably just a typo, I'm sure you meant "simply not enough weight transfer." However, this is counterintuitive. In traditional car design weight transfer can be reduced by making the track wider. Thus one might think that the narrow front axle track leads to massive weight transfer through that axle. The front axle does not have much weight transfer because the roll stiffness and wide track of the rear axle handles virtually all of the whole vehicles lateral weight transfer.
He also noted that scrub drag from the front wheels have nearly no moment arm about the vehicles CG. Thus the scrub drag applies very little turning torque to the vehicle, reducing understeer.
To the best of my knowledge: roll is roll, lateral twisting of the car... heave is vertical displacement. Bump and rebound are different directions of heave, and jounce is annoyingly used interchangeably with bump, but is really the derivative of jerk.
They said they used mountain bike shocks on the rear. My FSAE team used mountain bike shocks all the way around. :awe:
Depending on the rocker ratio they used (it looks large) they don't need a super-stiff spring or super strong damper to get high wheel rates for both.
This is more enlightening than what I got when I listened to the guy talk. Engineers sometimes just aren't so great at explaining things to relative laymen...
Harder to see for others or for the driver? I could see getting a bit disoriented and clipping an obstable with a rear tire...they just need find a way to widen the bodywork in the front without significantly changing the aero...so it'll look like an F1 Reliant Robin. :awe:
Saylick explained it all pretty well...I was just confused because the guy was discussing the damping, but not using the typical damping terms (bump/bound/jounce are all the same aren't they? and then rebound). I understand now why he was talking about roll so much relative to the damping setup. Although 'heave' still seems like an obscure Brit term to me.
Also I'm not a jerk. (really, all these terms start to make a technical discussion sound like an Abbot and Costello bit...)
That is exactly what he indicated it was in the video.
Oh, I agree that he showed what heave was. Just putting it into more precise words, that's all.