Aerodynamics.

[Wooders28 4719]

I would think race teams (Schumacher etc) have tested aeros and ground effects ,you can even buy a 1:10 off road rear diffuser! (I'm not sold on that one as its not actually close enough to the chassis to accelerate air for a start) 

 

I'm with the , shuttle /arrow , way of thinking, I've found when the rear wing disappears mid race, the handling goes skittery, but it's the jumps when you notice the most.

Schumacher's rear wing looks to have more in the way of vertical stabilizers.

They spend years developing cars, and nothing is overlooked or taken for granted, i seem to remember off-road tyre tread design under the aero spotlight?

(Or did I dream it?!?😯)

[Juggular 4961]

1 hour ago, Wooders28 said:

 i seem to remember off-road tyre tread design under the aero spotlight?

(Or did I dream it?!?😯)

2

I have heard of wheels made to fan the air out from under the chassis.  The risk for the civilian market is that if the wheels are put on the wrong side, they can blow the air under the car, and the car can fly up at highway speed.  I've seen "rain channeling" tires put on the wrong way, increasing the chance of hydroplaning.  You'd think, who'd do that?  But yeah, my brother rode his car's tire almost flat for a month and didn't even notice it.  (The lettering on the sidewall wore out completely)  

I haven't heard of off-road tread design being aerodynamic.  Since they are often within the wheel well, maybe they are not as important?  But I think "low-rolling resistance" tires are common?  It could be the sales hype. But I was looking for the lightest set of all-season tires, and Michelin Defender fit the bill.  The smoother the tread rolls, the more fuel you can save.  Only like 100 gallons over 50,000 mile period, though. That's not a lot, but it helps.  

 

[Mad Ax 9306]

5 hours ago, Wooders28 said:

I would think race teams (Schumacher etc) have tested aeros and ground effects

Robin Schumacher often puts in a brief appearance at the Iconic Revival in July.  If I'm still remembering this thread in 10 months time I might ask him what aero testing they do at the design shop.  Of course, he might not tell me

[Yalson 514]

19 hours ago, Wooders28 said:

I would think race teams (Schumacher etc) have tested aeros and ground effects ,you can even buy a 1:10 off road rear diffuser! (I'm not sold on that one as its not actually close enough to the chassis to accelerate air for a start) 

 

😯

The absolute state of that.

What I believe they are trying to do here is combine some kind of venturi tunnel with a 'monkey seat' secondary wing, in an effort to accelerate the airflow on the underside of the main wing and create more downforce. At least, that's what I have been able to establish. Everyone seems very cagey as to what the F1 monkey seat is actually for, with some people suggesting that it is actually for stalling the main rear wing at high speed, thereby reducing drag and increasing speed. My expertise does not extend to discerning which of these is correct, but of it is the latter then its utility on a 1:10 RC buggy would be precisely nil, as it wouldn't generate enough downforce to make this effective.

Neither of them will work. The venturi effort is just absurd and the monkey seat side has no fences to direct airflow, meaning that it will just spill over the sides rather than being pushed upwards. There is also the fact that, as we have already established, RC wings don't operate that way. You can accelerate the air on the underside of the wing all you like, as it isn't going to make any difference. File under "laughable".

If you're wondering what a proper monkey seat looks like, here is one from a 2016 Sauber. I used to have a picture from a Caterham which actually had a soft toy monkey in it, but I seem to have lost it.

[Yalson 514]

14 hours ago, Mad Ax said:

Robin Schumacher often puts in a brief appearance at the Iconic Revival in July.  If I'm still remembering this thread in 10 months time I might ask him what aero testing they do at the design shop.  Of course, he might not tell me

PLEASE DO!

I'm desperate to know if the manufacturers actually test this stuff and if it actually works.

[Yalson 514]

Of course, he might just say "of course it works" and walk off whistling. I'd imagine he'd be more genuine than that, though.

Unlike X-Ray here, advertising the tremendous (and completely fallacious) aerodynamic qualities of their 1:8 buggy.

Note how the airflow conveniently works over all the bits they want it to, but ignores the bits they don't, like the shocks and shock towers. It breezes straight through those to act on the supposedly downforce-inducing cockpit directly behind them.

And what of "side stability" which seems to just be two totally random words relating to nothing at all?

PULL THE OTHER ONE, LADS. IT'S GOT STREAMLINED BELLS ON.

[Yalson 514]

i can appreciate some companies making genuine but misguided efforts to create downforce on their cars, but that X-Ray effort is just hucksterism.

[Juggular 4961]

I don't know much about F-1.  So many wings!  I like how the side walls have 6 smaller wings of their own!  3 vertical slits under them look interesting.  I guess they allow air from under the big wing to go out, to reduce the turbulence created by those tiny wings.  (kinda like winglets at the wingtips smoothing out the turbulence.  It looks different but functionally similar?)   

Maybe the monkey seat is there to reduce the negative pressure under the big wing?  Also to help push the air out to the sides and to extract exhausts?  

The wing is there to give downforce.  The air under the wing will move faster.  Faster air = negative pressure.  But not just the downward direction, but sideways too.  The cavity under the wing can be a drag-zone because of the negative pressure.  The walls would want to crumble inwards.  That could be as draggy as driving with a big pool donut.  So making some holes on the side is logical.  But...

Without the monkey seat, the vertical slits will allow air back into the space under the wing (because it's the negative pressure zone).  The tiny wings will not have much effect.  Air deflected up can generate downforce.  If the air is sucked down, a lift is generated, despite the direction of the wings (just like wings won't lift if jet engines are pointing down).  A smaller monkey seat can add air pressure.  If the air pressure is too positive, then the monkey seat could end up lifting the big wing.  But since the monkey seat is small, it might be just enough to equalize the pressure.  In addition, I see that there are long vertical inlets funneling the air inward.  

The monkey seat and the side-funnels add positive pressure within the space under the big wing.  Slightly positive pressure lets air out through the smaller vertical slits on each side.  Mixing with the air through those smaller wings, allow air to go up, and thus create downforce... 

By the same token, the monkey seat will have some negative pressure under itself.  But you WANT to have some negative pressure near the tailpipe.  With regard to the exhaust, the monkey seat doubles as a passive gas extractor.    

The end result is, vertically downforce only.  But very little side-drag between the vertical walls under the big wing.  

The shape of the 60-degree wing is too much like an upside down flap.  Drag is fine when landing an aircraft, because you want to slow down.  When taking off, the flap angle can be changed.  Not F-1 wings.  So my guess is F-1 wing doubles as a drag chute to stabilize like the arrow feathers also (as Mad Ax said).  But too much drag isn't good.  A monkey seat can shoot up some air to smooth out the turbulence.  Why not have a shallow angle then?  Because the speed varies.  An F-1 car still wants downforce at slow speed, as well as high speed.  A monkey seat can shoot up more air at greater speed.  

I'm totally guessing, of course.  

 

[Wooders28 4719]

19 hours ago, Mad Ax said:

If I'm still remembering this thread in 10 months time I might ask him what aero testing they do at the design shop. 

Their design, development and race engineer, Tristram Neal maybe one to speak to! He did an interview a while back that was interesting :- 

http://astateofrc.com/wp-content/uploads/2018/05/ASORC-Trish-Neal.mp3

 

5 hours ago, Yalson said:

What I believe they are trying to do here is combine some kind of venturi tunnel

I'm not sure what they were meant to be doing, but downforce isn't even mentioned in the marketing blurb 🤔😂

* Original JConcepts design
* Compliments Finnisher & Silencer series bodies
* Durable, lightweight design
* Fits the Team Associated B6.1, T6.1, and SC6.1

Some of the aeros on the rear of F1 cars are designed to be , blown, using the high speed exhaust gasses to accelerate air. Even a flat piece of A4 paper will lift ,if you hold it in your hand and blow down it. Electric RC cars don't have that at their disposal (and can only nitro i can think of is the Schumacher Menace that exhausts at the rear?). 

 

[Yalson 514]

18 hours ago, Juggular said:

I don't know much about F-1.  So many wings!  I like how the side walls have 6 smaller wings of their own!  3 vertical slits under them look interesting.  I guess they allow air from under the big wing to go out, to reduce the turbulence created by those tiny wings.  (kinda like winglets at the wingtips smoothing out the turbulence.  It looks different but functionally similar?)   

Maybe the monkey seat is there to reduce the negative pressure under the big wing?  Also to help push the air out to the sides and to extract exhausts?  

The wing is there to give downforce.  The air under the wing will move faster.  Faster air = negative pressure.  But not just the downward direction, but sideways too.  The cavity under the wing can be a drag-zone because of the negative pressure.  The walls would want to crumble inwards.  That could be as draggy as driving with a big pool donut.  So making some holes on the side is logical.  But...

I don't think the slats at the side are wings. I think they are vents. As you said at one point, although the wing creates downforce, in doing so it also creates drag, which slows the car down when it wants to be going fast. When it is going down the straight, for example. This drag rises proportionally with speed, so the faster the car goes, the more drag the wing creates. The vents are a way of reducing that drag on the straights by bleeding air out through the slats as the speed (and therefore the air pressue within the 'bucket' area of the wing) increases. You will notice that the slats are only attached at one end, like the tear-off strips on a photocopied advert. This means that they may be designed to flex as the pressure inside the wong increases, thereby opening the gaos between the slats, reducing the pressure and partially stalling the wing. The car won't need this downforce on the straights, but it will need it in corners, especially high-speed ones. Itn could be that the monkey seat is designed to blow the underside of the wing, both by redirectng the exhaust upwards when the throttle is open on high-speed corners and by blowing the airstream on to the underside of the wing, thereby increasing the speed of the airflow and compensating for the loss of downforce caused by the vents.

If they do stall the wing by flexing, I would have thought they'd be considered a moveable aerodynamic device and therefore illegal. I thought the rules got tightened up in this regard after the furore over Red Bull's 'tea tray' splitter a few years ago, which was legal when the car was stationary in scrutineering, but which flexed under load and stalled the airflow under the car at speed, thereby reducing drag and increasing top speed. This was ruled legal at the time (one of those things that were not strictly illegal because nobody in the rulemaking body had thought of it and so thought to ban it) but it was my understanding that the rules were later changed. Clearly not.

[Yalson 514]

18 hours ago, Wooders28 said:

Their design, development and race engineer, Tristram Neal maybe one to speak to! He did an interview a while back that was interesting :- 

http://astateofrc.com/wp-content/uploads/2018/05/ASORC-Trish-Neal.mp3

So he agrees to what we have concluded here:

* Everything behind the front axle below the level of the height of the front wheels is a write-off as far as downforce is concerned, because the airflow is so messed up that it is useless for any practical purpose

* The rear wing does not create any aerodynamic downforce

* But it does create a small amount of Newtonian downforce by just smashing the air out of the way, as your hand does when you stick it out of the window of a moving car at an angle

* This creates a lot of drag

* Which is part of its function, as it is mainly there to provide stability over jumps, where it acts (in @Mad Ax's parlance) like the tail of a shuttlecock

* Nothing else on the car has any discernible aerodynamic effect

Which leads us to at least one unescapable conclusion

* That X-Ray advert is complete fantasy

It also seems that they have tried a car in a university wind tunnel, but the results were unedifying.

Seems we more or less worked all that out from basic principles!

[_oliK 108]

Some input from the world of RC Drift. Not necessarily applicable to buggies but still a testament to the effects 1:10 aerodynamics.

http://rextremerc.blogspot.com/2016/07/aero-seven-fourteen.html

http://rextremerc.blogspot.com/2015/03/re-xtreme-rocket-bunny-style.html

[Yalson 514]

27 minutes ago, _oliK said:

Some input from the world of RC Drift. Not necessarily applicable to buggies but still a testament to the effects 1:10 aerodynamics.

http://rextremerc.blogspot.com/2016/07/aero-seven-fourteen.html

http://rextremerc.blogspot.com/2015/03/re-xtreme-rocket-bunny-style.html

On-road 1:10 is a very different beast to off-road. Having a solid road surface, covered bodies and limited suspension travel makes the environment much more stable, especially given that drifting seems to involve mirror-flat surfaces. This chap seems to swear that the different aero components on the cars have a noticeable effect, but personally I am unconvinced that a wing that small could generate the results he is claiming at the speeds it is likely to reach. Also, apart from the front splitter, nothing is interacting with the road surface as he suggests, as the car is basically hollow underneath and there is nothing to channel the air through the diffusers.

Then again, drifting is a pretty weird RC niche and I don't entirely understand what the point is, but it certainly has its devotees and if this chap thinks that the modifications he mentions have an effect then maybe he is knows what he is talking about.

[Wooders28 4719]

6 hours ago, Yalson said:

So he agrees to what we have concluded here

Pretty much!

They do test, and will continue to do so, just not to the extent of needing a full time aerodynamicist. 

6 hours ago, Yalson said:

Seems we more or less worked all that out from basic principles!

Would have been easier ,me remembering that interview earlier! 😂😂

[_oliK 108]

It's true that having a flat, rock solid surface would likely play a huge part in this. Also, most RC Drift cars run muuuuuch softer suspension to allow for weight shift, so downforce is exaggerted compared to a hard touring car.

If there is any difference, then yes, I bet Russ is the guy who would be able to tell.

But as far as buggies are concerned, I agree. Thugh not having any real life experience the wings on there are probably leading only to minor downforce created by the rake angle and the weight of the part itself, plus stability at the expense of drag.

[Yalson 514]

13 hours ago, _oliK said:

But as far as buggies are concerned, I agree. Thugh not having any real life experience the wings on there are probably leading only to minor downforce created by the rake angle and the weight of the part itself, plus stability at the expense of drag.

Pretty much, yeah.