TLC show on Senna's fatal accident

[mnkywrch]

Apparently there was a TLC show last night that focused on Ayrton Senna's fatal incident.

For those who missed it (like I), it looks to be on again Sunday at 4pm.

Given that it's on TLC, I'd expect the piece to be relatively well-done.

[rabbit]

There was. Unfortunately, I didn't notice it was on until the last half hour, which they spent talking about an air-show crash. Thanks for the re-air info.

[chop456]

It's very well done. It focuses on what they believe (prove [?]) to be the true cause of the crash. Cold tires and ground clearance.

[mnkywrch]

Originally posted by chop456
It's very well done. It focuses on what they believe (prove [?]) to be the true cause of the crash. Cold tires and ground clearance.

Did Senna crash on the first time around after the safety car pulled off... or on his first time into Tamburello(sp) at full speed?

That's not the first time I've seen the cold tires/ground clearance conclusion.

But I'll be interested to watch and see how it could have run the car off the track.

[Ziggy]

Thanks for the heads up

I was under the impression that it was due to faulty machine work on the steering shaft. When bored from each end and meeting in the middle. This process should be done with a continuous bore, called "gun drilling". If the work (in this case the steering shaft) had not been properly indicated, the boring process would produce a shoulder where the two bores met. Shoulders are sharp corners, and thus subject to stress and fatique. I think Williams used a chemical machine process to hollow out the steering shafts, and again in this case, if the work done was not from center common on each end, a sharp corner would be the result.

The term "for want of a nail" has been associated with Tony Bettenhausen Sr for years.

Does anybody on this board know why???

Ziggy

[chop456]

Originally posted by Ziggy
Thanks for the heads up

I was under the impression that it was due to faulty machine work on the steering shaft.
Ziggy


What they said disproved that theory was that the telemetry showed steering input until the moment of impact. Their theory was that the restart allowed the tires to cool and deflate slightly. The first time through Tamburello at speed, the lowered car skipped on a high piece of pavement, causing the nose to point left. Senna countersteered just as he should have, but then the fronts gripped, pointing the car back to the right and off the track.

[devilmaster]

Originally posted by chop456
What they said disproved that theory was that the telemetry showed steering input until the moment of impact. Their theory was that the restart allowed the tires to cool and deflate slightly. The first time through Tamburello at speed, the lowered car skipped on a high piece of pavement, causing the nose to point left. Senna countersteered just as he should have, but then the fronts gripped, pointing the car back to the right and off the track.

Not being an expert on this (let me say that off the bat), when I read what you said chop, about the show saying that there was input right up until impact, a question immediately popped into my head. :saywhat:

Correct me if I'm wrong guys, but where would the telemetry sensor be for the steering wheel? We all know that when a driver is going to make a big impact, he lets go of the wheel because holding on to the wheel could break a wrist or an arm.

Now, if the steering wheel did break off (an idea I believe has merits, from what I have seen) when Senna plows through the sand trap, the wheels would be violently jerked around. If the sensor is on the shaft or on the steering arm, then it should register steering input. The only difference is that the input is being done by the ground, not the driver.

Just my take on it.

Steve

p.s. chop, after I read my post, I wanted to make sure it didn't sound like I was doubting you. I meant the show.

[mnkywrch]

Originally posted by Ziggy
The term "for want of a nail" has been associated with Tony Bettenhausen Sr for years.

Does anybody on this board know why???


I'll bite - I've got no idea.

[Ziggy]

Tony Sr. was testing a car for Paul Russo. Russo had complained that it was not handling very well. They had tried everything, and had the car torn down a few times in search of the gremlins.

Tony went out and the results were catastrophic. One of the bolts had backed off (and I think it was the steering link) then fell off. Someone forgot to put a cotter pin in it's hole, or didn't bent it over properly. They found the nut in turn 3, then the bolt in turn 4. The car veered out of control coming down the main straight, vaulted the wall and started endowing in the fence.

Tony B was gone......

When folks compile lists of "greatest drivers" (In US of course) more often than not Tony Bettenhausen Sr. is omitted.

1950 - 1961
Races 92
Money Won $224,544
Laps 8737
Laps Led 2220
Wins 16
Poles 12
Top 5 37
National Driving Champion 1951, 1958

Dude could bring it.

Ziggy

PS - I realize that this is a bit off topic. Race Car preparation is serious business. There are other examples of mechanical failure which resulted in grave injuries or death. You can never spend too much time on a race car making sure it is not going to fall apart on you.

[Napoleon]

Originally posted by Ziggy
One of the bolts had backed off (and I think it was the steering link) then fell off. Someone forgot to put a cotter pin in it's hole, or didn't bent it over properly.

Thats why people like Carroll Smith in his book "Prepare to Win" suggest that every fastener should be marked with wax pencil, or something like that, each time its installed and that upon completion of whatever work you are doing you go back and check each bolt to make sure you marked it. You can not be to sure.

[Railbird]

The TLC show is very in depth with much of the info brought out in the Italian inquiry. I believe their conclusion on the steering column was drawn from the steering movement and the front wheel deflections matching right up until impact.

On Ziggy's reflections about the Bettenhausen death. The car Tony B died in was the Stearly Motor Frieght spl which had carried Ward to his '59 win. Doug Stearly the owner was the acting chief mechanic and was obviously out of his element. Not only was the fastener not properly secured, the bolt was installed in a "head down" manner which guaranteed the bolt would fall out if the nut worked loose.

The amazing part about all that was the fact that Russo was a life long mechanic himself. Why he didn't spot that glaring safety defect himself is beyond me.

[Napoleon]

Originally posted by Railbird
Not only was the fastener not properly secured, the bolt was installed in a "head down" manner which guaranteed the bolt would fall out if the nut worked loose.

Now thats stupid.

[Joe in LA]

On the Senna accident and cause: It was the first time through Tamborello (sp?) at speed after the "safety" car IIRC.

The bad news--the Italian Supreme Court has apparently taken up the dismissal of the case against Newey and Head. Nothing's decided yet, but what everyone thought was over in 1999, may be openned up again.

[Ziggy]

I taped the program, so thanks again for the heads up. I watched it after the SuperBowl. I now agree with the car bottoming out. What I did find alarming is the deflection of the steering wheel shaft. I remembered that Senna had requested the longer length shaft, and never understood why they didn't just put a one piece shaft in of the desired length. Welding a segment in just looks like trouble. Is this where the deflection comes from? I have raced a few different types of 4 wheel vehicles. I have always taken great confidence on the rigidness of the steering shaft, be it cars or karts. I find it odd that having a noodle for a steering shaft is acceptable in any racing car....

Ziggy

[RTKar]

I remember the Williams that year being described as a "nervous" or "twitchy" car. I wonder if they were consistently running the thing too close to the ground to maximize downforce to make up for perceived aero deficiencies elsewhere on the chassis?

[mnkywrch]

Originally posted by Joe in LA
The bad news--the Italian Supreme Court has apparently taken up the dismissal of the case against Newey and Head. Nothing's decided yet, but what everyone thought was over in 1999, may be openned up again.

What I don't understand is the insistance on the part of the Italian courts on this matter.

Are they that convinced the team was negligent?

Is it cultural?

(And I'm half-Italian.)

[Joe in LA]

My understanding is that any accidental death MUST be investigated and blame assigned. As I recall it, there is criminal responsibility at a level of culpability we would not expect in our system. In this case the issue is that the judge did not reach a conclusion as to who was responsible for the accident, and simply concluding that Head and Newey weren't responsible without concluding who/what was responsible may not satisfy the Italian laws.

[911]

Originally posted by Joe in LA
On the Senna accident and cause: It was the first time through Tamborello (sp?) at speed after the "safety" car IIRC.


I believe the shunt occured on the 2nd lap after the Safety Car pulled into the pits. I remember Schumacher saying that Senna nearly lost it at Tamburello the lap before his accident.

That day - May 1, 1994 - is still the darkest day for me w/ motor sports. :(

[Badger]

Originally posted by RTKar
I remember the Williams that year being described as a "nervous" or "twitchy" car. I wonder if they were consistently running the thing too close to the ground to maximize downforce to make up for perceived aero deficiencies elsewhere on the chassis?

This was the first year after the banning of active suspensions. Basically, Williams had developed a car that relied on the self leveling ability of the active suspension and when this was taken away, they were left with a very difficult car to drive that was very pitch sensitive. I don't think it was coincidence that the Williams the following year had a raised nose, which typically reduces pitch sensitivity.

As far as the crash, I saw a few minutes of the show but I am still unconvinced that Senna's only response upon losing it, was to head straight to the fence with little sign of steering correction. I still think the car appeared to dart off to the right more than a normal amount and not in a manner that would occur if the bottom rear of the car bottomed out.

[chop456]

Originally posted by Badger
This was the first year after the banning of active suspensions. Basically, Williams had developed a car that relied on the self leveling ability of the active suspension and when this was taken away, they were left with a very difficult car to drive that was very pitch sensitive. I don't think it was coincidence that the Williams the following year had a raised nose, which typically reduces pitch sensitivity.

As far as the crash, I saw a few minutes of the show but I am still unconvinced that Senna's only response upon losing it, was to head straight to the fence with little sign of steering correction. I still think the car appeared to dart off to the right more than a normal amount and not in a manner that would occur if the bottom rear of the car bottomed out.

Maybe it's just because I'm a novice, but it made sense to me.

The car bottoms out in a left-hander. The natural tendency is for the rear to step out to the right, and obviously for the nose to point left. It does, and Ayrton countersteers. The car grips at that point, sending it right in the direction the front wheels are pointing - off the right side of the track.

Probably an oversimplification on my part and theirs, but it sounds reasonable.

Let's also keep in mind that it could have very well been a survivable accident if not for the front suspension. Compare the crash to Blundell's at Rio.

[Warlock!]

Originally posted by chop456

Let's also keep in mind that it could have very well been a survivable accident if not for the front suspension. Compare the crash to Blundell's at Rio.
Or to Berger's at the exact same place (Tamborello). Only difference was Berger's car burst into flames.

Winter Warlock!

[Napoleon]

Originally posted by Badger
As far as the crash, I saw a few minutes of the show but I am still unconvinced that Senna's only response upon losing it, was to head straight to the fence with little sign of steering correction.

I don't think thats what they said. I took what they stated to mean that once the back stepped out and he turned into the slide the car caught and headed for the fence. I did not take it the after that point he made "little sign of steering correction" but that it was to late for him to do anything to effect the path of the car.

[Joe in LA]

Originally posted by Warlock!
Or to Berger's at the exact same place (Tamborello). Only difference was Berger's car burst into flames.

Winter Warlock!

I remember watching the accident happen and thinking "He'll be fine, doesn't look near as bad as Berger's crash".

[rabbit]

Originally posted by Badger
As far as the crash, I saw a few minutes of the show but I am still unconvinced that Senna's only response upon losing it, was to head straight to the fence with little sign of steering correction. I still think the car appeared to dart off to the right more than a normal amount and not in a manner that would occur if the bottom rear of the car bottomed out.

Tamburello was a lot like an oval track turn. Ask anyone who's raced at Indy and they'll tell you there's nothing scarier than having the back end step out and then have the front hook up just as you're correcting (see also Fox, Stan). That is what happened. The reason the car appeared to go straight is because the runoff area was actually lower than the track surface, so there was a spilt second periond of time where the car was essentially airborn and no amount of sterring input would have changed the direction of the car.

I don't buy the broken steering shaft theory for this reason: If the steering shaft did break while the wheels were turned in a high-G corner, the wheels would not have straightened out, but would have suddenly turned full left and thrown the car into a spin. At least that's how it seems it would happen. I'm no expert.

[Napoleon]

Originally posted by rabbit
If the steering shaft did break while the wheels were turned in a high-G corner, the wheels would not have straightened out, but would have suddenly turned full left and thrown the car into a spin. At least that's how it seems it would happen. I'm no expert.

That depends on the caster of the front axle (the tricycle effect)and toe-in. Let go of the wheel on your street car and see what happens. The result is the same as if your steering shaft broke.

[mnkywrch]

If the shaft had broken, wouldn't there have been a GIANT jerk to the left?

I don't recall seeing that on the in-car video (http://www.cineca.it/visit/Researches/Senna/index.html).

But you can see the shower of sparks from under Senna's car just as it flys off the track.

[Napoleon]

Maybe I should expand upon my earlier post. Wheels/axles have certain parameters. Spacecrafts and ships have yaw, pitch and roll and car wheel/axles have toe, camber and caster.

For example toe-in/toe-out is the amount the tires/wheels vary from facing directly forward. To the extent it varies is a result of the front axles being something other then perfectly perpendicular to the centerline of the long axis of the chassis.

Camber is the measure of how much each tire/wheel varies from being perfectly up and down. Racecars always carry enough negative camber so that under load (which compresses and bends suspensions in corners) the camber is such that it is within the optimum range for the tires grips to be maximized. I think that is 1.5 negative. I assume all modern streetcars similarly always have negative camber (historical note – if you ever see a horse buggy check the camber. It’s usually positive, which I assume is done to make the vehicle less likely to flip. If you watch footage of early cars they have positive camber, like the horse carriages of the day. Somewhere along the line some engineer realized they should not be copying horse carriage designs for cars).

Anyway one other parameter you usually do not hear discussed on race broadcast, is caster, or kingpin inclination. This one is a little harder to describe. The wheels axle (at least any wheel that can turn) can rotate from side to side. This is the motion that turns the wheel so you could steer to the left or the right. The axis around which the axle turns is roughly perpendicular to the road surface, but always varies in that the top of the axis is behind the axle and the bottom ahead of it. The part that acts as the axis upon which the axle rotates is called the king pin. Just picture in your head what the front fork of a tricycle looks like, which has extreme king pin inclination. This rearward inclination forces the wheel to return to the straight-ahead position if there is no steering input. The more rearward the inclination the more force is there exerted to return the front axles to as near a perpendicular to the long (front back) axis of the car as possible. If you recall from your tricycle days you could let go of the handlebars the front wheel would immediately return to center. As far as I know the only downside to increasing king pin inclination is to increase the amount of steering imput needed to turn the wheels.

The Williams should have been built with sufficient king pin inclination to cause the wheels to return to center if the steering shaft broke, or the driver was no longer inputting steering.

[j_d]

I saw the TLC show with my 7-year-old son. We were both fascinated; he fell asleep during the latter part of the report and couldn't wait to find out what he missed once he awoke. I thought it was well-done, objective, and that its conclusions made sense. Did anyone watch the second half of the program about the Russian jets colliding in mid-air at an air show in the UK where one jet sliced through the other, and both pilots survived? Amazing.

[Napoleon]

BTW - a clarification to my earlier post which made an over simplification. On a tricycle (or bicycle for that matter) since the front wheel is under the "king pin" more or less and captured on both sides by the forks it will self center. Functionally front wheels on car will do that, if the steering box and all the linking mechanicals to the front wheels are in tack (I am not talking about the steeing column just the stuff that makes the wheels work in tandum). If for some reason the link between the wheels were broken then I beleive they would both "flop" to the outside. By being tied together they force the car to steer straight if no other force is turning the wheels.

[rabbit]

Nappy, so what you're saying is that if the shaft did break, the car would indeed go straight?

[Napoleon]

I see no reason why it would not have been designed to go straight it there was suddenly no steering imput, regardless of why. Its the simple application of long known engineering principles. Without going into detail I have a hard time imagining a situation where the designed in tendecy of the front wheels to center would be overcome by outside forces.

On a related note I talked to my brother after the TLC show ran (which I taped and called him to see if he wanted it). He started talking about an in car cam tape he had seen once of Senna qualifying and how he worked in a car. Interestingly part of his discription actually included one part where Senna actually depended on the fact that this tendency was engineered into the car. In coming out of a corner (I think a hairpin) he actually takes his hand off the steering wheel and allowed it to self center.

[RichK]

Originally posted by Napoleon
In coming out of a corner (I think a hairpin) he actually takes his hand off the steering wheel and allowed it to self center.

I've seen autocross racers do that. I think it's because road cars require too many steering wheel turns.