[CJA]

Ey Up Andi.

I'm not sure about this.

If the car pivoted about the rear axle, then yes the "trailing" front wheels would need to turn sharper cos they would be prescribing a curve of lesser radius.

In fact the car does not rotate about the rear axle, it is moving forward all the time.

Not 100% sure, but I reckon that the two front wheels on each side need to turn by the same amount, the two sides being different in true Ackermann operation.

Interesting problem.

vbr Chris A.

 

[Race-Jan]

The arc of the guide pin does not have to be an issue if you use two independent connecting rods to the steering knuckles.

The basic principle is that you will have to have the inner wheels steer more than the outer wheels, AND the fronts slightly more than the rears.
So: inner front steers the most, outer rear steers the least. outer front and inner rear both are somewhere inbetween...

I could come up with a version in which the rears (both of them) steer more than the fronts, that's easy

but in this configuration it's either both rear wheels steer more, equal amounts or less.

Then again, it may not be pleasing to the eye, but what can you do if that's the way it works?

On another note: it would be interesting to know if we have a "leading" or a "trailing" front axle. All depends on where the steering rack was fitted.

Here is some authentic Youtube footage, especially interesting at the end (top view of the car without bodywork @Monaco, going through the twisty bits and you can actually see the steering working).

Hope it helps a bit

Jan(edited: corrected a rather obvious mistake)

 

[conti_rowland]

QUOTE (Race-Jan @ 20 Oct 2011, 13:55) <{POST_SNAPBACK}>
you will have to have the outer wheels steer more than the inner wheels, AND the fronts slightly more than the rears.
So: inner front steers the most, outer rear steers the least. outer front and inner rear both are somewhere inbetween...

Jan

Are you sure Jan?

My own work has led me to believe that isn't quite right:

Of course at the point that the maximum steering angle is much larger (as it might have been in the real car but not in my slot version) the outer front might 'overtake' the inner rear such that the angles switch.

All in all however you can see that it is quite counter intuitive when all drawn out.

This was one of my closest attempts:

And this was the actual version I opted for:

BUT I can be wrong still - I am not a mechanical engineer so am more than happy if someone enlightens me......

 

[CJA]

Hey Jan,

the P34 is my favourite F1 car of all time, but I have never seen that body-off Monaco footage before. Fantastic.

And you can really see how the steering operates !!.

In all the footage I've seen of the car, and watching live at Monaco at the GP Historique, I had never noticed the strange steering geometry before.

Andi, it does look weird, but that is how it works.

Jan many thanks for that link.

vbr Chris A.

 

[howmet tx]

Or in honour of Al 'BWA' Penrose you could just let them all trail steer- they'll find their own path....

 

[Race-Jan]

@Chris: You're welcome, looks as if you've enjoyed it as much as I have.

@Andi: Being Dutch here I'm afraid there is something of a language barrier...

In the first picture you show the car on the right shows exactly what I tried to say... [edit] Just noted the glaring mistake I made... Of course the inner wheels steer more than the outer! [/edit]
Instead of "steer" please read "angle with centerline of car".

Of course having the pivot points outside the hubs doesn't help...

Babylon here we come

Jan (not a mechanical engineer either, always open to other opinions)

Trail steer? How where's the fun in that ?

Hat, coat, outta here

 

[conti_rowland]

QUOTE (howmet tx @ 20 Oct 2011, 15:16) <{POST_SNAPBACK}>Or in honour of Al 'BWA' Penrose you could just let them all trail steer- they'll find their own path....

Errrr, did that ever actually work. I once asked Al to show photos of the complete car but as far as i know he never did.....

Plus it would require that all wheels touched the ground all the time.

Plus if any oscillatory vibration ever occured............

Don't really think it'd work on the Tyrrell somehow

PS Jan the footage was indeed great although I personally couldn't quite see the exact steering geometry one way or the other.

Thanks for the discussion....

 

[Julian_Boolean]

Dunno if it helps, but Panther made a 6 wheeled road car with 4 front wheels, called in a true bit of creative genius the "6"

 

[bwaminispeed]

Pretty cool.

Yes, I have posted my trail steer car several times.

It would work just fine with one axle or ten, and, all wheels would just naturally follow their correct path, and, no need to connect it to the guide (kind of counter productive to have trail steer connected to the guide)

At least one wheel of each axle must be on the ground, and, it can be Ackerman or non Ackerman. Apparently Lotus did not use Ackerman steering in their F1 cars.

Will post pics again later.

 

[munter]

I made a car using the matchbox kit.I didnt do anything too radical in the chassis department ....except for the front axle arrangement.
I made a four wheel bogey and allowed it to tilt a few mm front to back.
I also did what Conti Rowland has done with the fronts and sleeved them with brass tube.I used small axle spacers epoxied on the inner and outer edges to hold the wheels in place. A BWA bracket,Slotit rear end, some brass rod and we are away laughing.
The nose piece for the body has a piano wire brace glued up and under to keep it together.

I am following this thread with interest as I have great admiration for the authors work and general approach to building cars.....its fresh !
So please build on, sir.

regards

 

[John Cahill]

I laid this out too...maybe I'm missing something (undoubtedly!) but I didn't get the extreme wheel angles shown earlier.
Meanwhile, since this is actually a slot car and the dynamics are different from a real car (among other things you don't
actually gain from lateral traction at the front), I would seriously go with the trailing wheels ala Al Pennrose and minimize drag.

That being said...all of this is beautiful work...Al's craftmanship and the drafting/engineering efforts of Jan and Andi.
Lovely stuff!

John

 

[conti_rowland]

I think the trailing axis idea is great up to a point. I'm concerned on several levels whuch I guess wouldneed to be tested but i'm not going to risk.
1. With two front axles I feel there is a real risk that at certain times the two wheels might point in different directions which wouldn't look too authentic! This might be exaserpated by the fact that here we run on Ninco not on smooth routed.
2. With tyres that are almost as wide as their diameter I personally am worried that the drag created by only one touching the ground might not have the effect that Al's cars have.

I can be soooo wrong but don't want to risk.

Then I LIKE that when I pick the car up and twiddle the guide all four wheels will turn.....

Plus of course i've made the axles now and I really CAN'T do them again.

Finally, i'm worried that your diagram isn't really quite right. You do need to consider the rear axle especially on non-diff cars.

 

[howmet tx]

The first trail steer car I built went great on my Scalextric track at home, but turned out to be rubbish on wooden tracks. I've built a few since then with no problems at all on any surface. No rocket science involved at all. I can't really imagine why a four wheel steering set-up should not work any differently, but each to his own! Smashing project!

 

[conti_rowland]

So I've made sufficient progress to post a bit more.

My ideas about my builds are centred on what I call 'conceptual symmetry'. To me that means trying to build into the model the most important concepts of a given design when it was of course new and real.

For the P34 the most important thing then was the four front wheel steering for which it was unique in F1. However like most cars of its era it also had a monocoque 'one egg' in French and finally it had a fully stressed motor (the ol' DFV) to which the rear end was then fixed.

So that is what my model has. 4 front wheel steering, a stressed skin monocoque made of metal and a motor bolted to it such that the rear 'suspension' and 'gearbox' are floating off the back of it.

Got a few test laps in last night and it seems fairly interesting.

Obviously a LOT of finishjng still to be done....

Andi

 

[Mirrorman]

Stunning work Andi, and fascinating as always to see your progression with your projects and attention to detail.

Skills in metal work & soldering always make me envious ..... in a good way ofcourse.

 

[1000simca]

Hi Andi ...

... I'm freaking out about your work. I had already seen the other formula 1, and of course the Vanwall and I was impressed with its detail and its good work ... (although I am just arrived, and took time going through here "shadow")

... but with this I've touched a nerve, I am a lover of Tyrrell, and 6 wheels kill me... ... in the photo of another post, do not guess it was to address, and as my English is so bad, I find half ... but after going through here .. mamma mia!
... I also made the front wheels 4 addressable (and I put it in another post) but turn the 4 parallel, at least in theory ... of course you've Hido kilometers (or miles) farther than me, and I can not say what it says on the last point, all 4 wheels, monocoque construction, engine and suspension, is what best I've seen here ...

I follow your progress closely ...i need more, and more..

a greeting.
Carlos.

PS: if I can suggest to update the title of the post, including the model and is in the direction .. I'm sure most people still come to see ...

 

[RikoRocket]

This fabulous stuff. Andi is the motor to gear stiffness adequate enough with that tiny wire to stop pinion to contrate movement?

 

[conti_rowland]

Thanks for the general positive comments.

QUOTE (RikoRocket @ 12 Nov 2011, 22:15) <{POST_SNAPBACK}>is the motor to gear stiffness adequate enough with that tiny wire to stop pinion to contrate movement?

What I love about this forum and sloting in general is that in many ways the problems are limited but the solutions almost infinite.

In my 2 or so years on here i've learnt so much from watching other people and what they do and the trip to EB's helped enormously too.

This car then is my first attempt to take hard learned lessons from others and adapt it to my unique approach!

So instead or rigid with suspension i'm trying to go flexible since that's what I see you pro's doing..... I learnt alot from David Lawson for example.

Of course, with the motor rigid the rear end had to rotatevaround the pinion and so as you so easily saw the problem is avoiding pinion contrate movement. My solution is that there is a circular brass collar fitted tightly around the motor shaft bearing housing that means that only rotation is possible and no other movement.

Certainly tollerance means, as i'm sure you're suggesting that this can never be perfect especially since torsion creates an in and out movement too but it seems to work so far.

I reckon it will last race distance and if it explodes on the line? Well many in F1 history would say that was a job well done........

Thanks to all

Andi

 

[RSCLIO]

This looks sensational.
So much so I went and read all you're other builds
All to the same standard - very inspirational

 

[Graham Lane]

I'm fortunate enough to have seen this build in the flesh, so to speak, and see it zip round the track at Brama. I can tell you that this is an exquisite piece of model engineering as I have ever seen; just like, but different to, Andi's superb Vanwall. When he finished that one he told me never again, but he seems to have got enormous pleasure out of this Tyrell, probably because he didn't have the deadline of preparing it for an event. What's next?