DAS Dual Axis Steering...Legality??

[nevill3]

I think we need to separate the DAS discussion from the W11, Preseason Testing and Mercedes threads. Especially the car thread.

Many of the discussions are going in circles so having them separate will stop the pollution of the other threads.

I personally admire the out the box thinking and ingenuity of the Mercedes team and think it should stay, I even think that the 2021 new regulation attempting to ban it can be circumvented with a little design ingenuity that replaces the push pull activation and combine it someway with the rotational movement of the steering wheel

[Xwang]

Can DAS be implemented with two racks with angled teeth (one for each wheel connected to the toe arms) and a dual helical gear fixed with the translating pignon like in the following drawing?
If so it doesn't seem something complicated to copy from the conceptual point of view.

[henry]

Can DAS be implemented with two racks with angled teeth (one for each wheel connected to the toe arms) and a dual helical gear fixed with the translating pignon like in the following drawing?
If so it doesn't seem something complicated to copy from the conceptual point of view.
https://postimg.cc/VSSmXD3r

That certainly looks like it would work. The helix angle would be quite shallow. However the linear movement of the steering wheel looks to be too much for such a solution. It would make the steering rack quite deep at right angles to the bulkhead. It would however prevent kick back, that is wheel alignment torque, from whatever cause, translating the steering wheel.

[bucker]

I think we need to stop debating about DAS at all. FIA said it is legal, so there is no sense that forum users debate about legality.

[PhillipM]

I think you'd have some serious issues with steering feedback given the backlash required to make that work Xwang.

[nevill3]

I think we need to stop debating about DAS at all. FIA said it is legal, so there is no sense that forum users debate about legality.

As a technical forum the discussion of this and any other new invention is exactly why I come here. But everything has it's place.

[jjn9128]

I think we need to stop debating about DAS at all. FIA said it is legal, so there is no sense that forum users debate about legality.

It's an important and maybe slightly anal distinction, but the FIA haven't actually said it's legal. They have given their opinion that the system is legal, but the definitive word on any cars legality lies with stewards at the first race of the year. Because the FIA are of the opinion the system is fine I'd expect it to pass scrutineering but would also expect one or more teams to appeal after the fact. There's also the possibility the stewards take a different opinion and don't allow it but Mercedes run it under appeal in either case the result of Melbourne would be decided in the court room.

[Xwang]

I think you'd have some serious issues with steering feedback given the backlash required to make that work Xwang.

The drawing was just to give an idea of a possible arrangement not to say that the number of teeth, the gear ratio and the helical angle depicted (10°) are the correct ones.
In any case if we consider the toe arm attached at 6.5" from the steering axis, a transversal movement of 2.88mm is needed to change 1° of toe when steering is 0.
Such a movement is given by an helical path 1.65° if a longitudinal movement of 10cm is taken in consideration for the steering wheel.
I hope I have not done any error in my calculation and I do not have specific experience in this field of the engineering to know if such an arrangement would give issues but it seems that the system should be not reversible from the point of view of the longitudinal movement of the steering wheel column because a huge force exerted from the toe arm would give rise to a small longitudinal force of the steering wheel while on the other side, a little pushing force from the pilot side would give a high force on the toe arm.
With the numbers above the ratio between toe arm force and steering wheel one is 0.0288 (and a preloaded spring could be added to keep the steering wheel in the cornering position so that the pilot do not have to push and turn the wheel at the same time).
Of course the servo hydraulic steering system should be made in a way to not interfere badly with the DAS (and I think that modifying the servo steering is the most difficult part in case someone want to adopt this system to their car in a rush).

PS I do not know if this tread is the correct one to discuss how DAS could be implemented (I am not discussing if it is legal or not. If it is not should I move this post and the image in anew discussion but I thought that too much different discussions which cover different aspects of the same innovation could be not easy to follow. Let me know please if I have to move. I do not want to go OT).

[nevill3]

Do you think this system will allow Mercedes to run with extra toe out to improve the cornering ability and balance of their car in the corners?
From what I understand, the teams use of toe out has always been limited in it's setting by the adverse effects excessive toe out would have when driving in a straight line and so it has always been a compromise. Using this new system would allow for more toe out to be used to enhance the cars cornering speeds.

I would envisage the drivers eventually being able to have two or three positions depending on the amount of toe out when first set, rather than the either in or out of the steering wheel as it appears now.

[Xwang]

Do you think this system will allow Mercedes to run with extra toe out to improve the cornering ability and balance of their car in the corners?
From what I understand, the teams use of toe out has always been limited in it's setting by the adverse effects excessive toe out would have when driving in a straight line and so it has always been a compromise. Using this new system would allow for more toe out to be used to enhance the cars cornering speeds.

I would envisage the drivers eventually being able to have two or three positions depending on the amount of toe out when first set, rather than the either in or out of the steering wheel as it appears now.

I haven't made any calculation, but I think that the first gain is nullifying the additional drag given by front tyres when running along a straight.
If the toe is 1°it is the 1.7% of the lateral tyre force produced at 1° of "slip" angle.
I suppose that the toe angle F1 teams are using is a compromise between the one needed to optimize cornering performances and behaviour and the one for the straight.
So it is very luckily that they can use two sets of value (cornering/straight) or more (with different longitudinal positions which the pilot can recognise as the one used in aircraft throttles to permit to the fighter pilot to recognize the idle, max dry, max afterburner and combat positions)

[seinfeld]

this is adjusting the CASTOR not the toe.
to adjust toe along the straights you would have to counteract the forces on the tyres at 300km/h impossible to do
as the wheels toe out the faster you go.
castor on the other hand is where the cornering counts. This is what they are changing. and it makes sense castor is the wheels going towards the wing to aid in cornering = + (positive) castor 4-6 degrees
wheels going AFT or to the rear is reducing castor aids in straight line speed and less tyre wear
also adjust castor BY A LOT it actually alters ride height (talking only mm) but it is still a lot when you talk about aero and diffuser performance . the lower the better

[PhillipM]

Where on earth did you pull that from?
It's easy to adjust the toe, the steering wheel does it all the time, by steering.

And adjusting the castor would be illegal by the regs.

[trinidefender]

https://www.motorsport.com/f1/news/das- ... t/4691684/

This article makes an interesting point. While the DAS system may be legal as far as the technical regulations state, it may fall foul of the parc fermé rules.

The interesting bit is that Mercedes claims that this system affects the steering, not the suspension so therefore it isn't an adjustable suspension which would be illegal.

It's stated that suspension changes are not allowed under park fermé rules. If it's decided that the DAS system is legal due to it not being part of the suspension system and parc fermé rules state that steering isn't against parc fermé rules then effectively it should mean that all teams should be allowed to adjust toe angles while in parc fermé as toe angles must therefore be considered a steering change and not a suspension change.

Seems there might be some far reaching influences and consequences as far as this system goes.

[damager21]

It's stated that suspension changes are not allowed under park fermé rules. If it's decided that the DAS system is legal due to it not being part of the suspension system and parc fermé rules state that steering isn't against parc fermé rules then effectively it should mean that all teams should be allowed to adjust toe angles while in parc fermé as toe angles must therefore be considered a steering change and not a suspension change.

Seems there might be some far reaching influences and consequences as far as this system goes.

The argument would be that Yes, all teams can change toe angle in parc fermé without any modification to suspension. So if they wish to do that... please go ahead.

But the question is, why would any team change toe angle because unlike Merc, they wont be able to reset it while driving in the race unless they have DAS.

If FIA has said DAS is legal, then it is clear that it is not considered to be guided by suspension rules so same would apply for parc fermé as well.

DAS as of now is considered as a part of the steering system. It can get banned only if teams are able to decode it be bringing about a change in Aero configuration

[AJI]

While I think the DAS toe adjustment is truly clever in its simplicity, Newey has a pretty good point and the aero argument is quickly gaining momentum...
I doubt it'll make the cut.