Robert kubica seriously injured

[skwdenyer]

dr_gn said:

It was actually a turbine disc failure. The reason that there is no containment system for this part of the engine is becasue the discs are are so heavy and are spinning so fast that there is no reasonable way to design a system that would contain that much energy. Much like you couldn't design a workable containment system to prevent the edge of an armco barrier from penetrating a car travelling at 60mph or so: it would be so heavy that it would be unworkable. The design of a containment system for a blade-off event is nothing compared with what would be required for a disc failure.

I've now read the later reports on the A380 Trent 900 failure. It wasn't a "straightforward" turbine disc failure of the type that caused the damage to, say, that MD-88. That one was caused by fatigue cracks propagating around poorly-finished machined holes in the disc, which grew over time until the disc failed. The initial failure was manufacturing / QA, followed by a poor maintenance and inspection regime.

The Trent 900 failure has been attributed to a fatigue crack / failure in an oil pipe, which in turn was caused by faulty manufacturing (the boring was off-centre, so one side of the pipe was thinner than the other, leading to strains during normal service sufficient to cause cracking). The pipe failed, oil leaked where it shouldn't have, that caught fire, which then caused bearing failure and what is euphemistically called a "IP turbine disc liberation event".

From an engineering standpoint, it would be perfectly feasible to design a containment system to deal with an IP turbine disc failure - yes, the forces are very, very large, but each individual part is not all that heavy. The bypass duct would be the prime candidate for upgrading to provide containment; from my work on those ducts, and on FOD damage to CF-skinned sandwich structures, I am confident significant containment could be provided - for instance, by borrowing high fibre volume fraction and knitting techniques developed by Defence Clothing and Textile Agency for FOD-abatement helmets and armour systems, coupled with the existing containment technology used for fan blades. However, such a structure carries a large weight penalty, which impacts upon all aspects of the airframe's design and allowable payload. The reliability of turbine and compressor discs is sufficient, on average, for the penalty to be deemed unnecessary - certainly that's the view from the places I worked in the industry.

Given my experience of Rolls, I'm surprised that their QA didn't pick up the pipe issue. I suspect that won't be a problem again...

For reference, when I suggested a disc failure was uncontainable, I was referring to fan and/or first/second stage compressor discs, all of which would inevitably lead to the loss of the fan. For me, that's the least comfortable outcome.

Returning to the Armco barrier, I explicitly said that it would be heavy. But that doesn't mean it is unworkable - anything can be bolted to the car if it is deemed expedient to provide it. If you can find me a budget then I'll do the modelling on a system related to those on aircraft engines. I'm confident I could provide something for a penalty of no more than 10-20kg or so, and possibly much less if you've got more time and monbey. As I say, that would have to be mandated, and I doubt it would be, but that doesn't make it unworkable IMHO if the objective is to prevent a recurrence.

dr_gn said:

Just like the jet engine turbine disc, it's far better to design things such that the chances of failure are so small as to be acceptable, just like the chances of an armco barrier failing in such a way as to skewer a rally car. Jet engines won't be required to contain disc failures after the A380 incident, nor will rally cars have to be redesigned to prevent penetration by safety barriers after Kubica's accident.

I agree with the first part, and I suspect you're right about the second. My point was an engineering one - it can be done, and it needn't weigh so much as to be impossible to deal with.

If we're going to get technical about it, let's consider the forces involved. A World Rally Car weighs 1230 kg. At 60 mph (26.8224 m/s) it has kinetic energy of 0.44 MJ. I've pulled the drawings of standard Armco sections; I'm estimating the cross-section to be around 1265 mm2.

Now, let's compare this to something we know how to stop, such as a bullet. Choosing a large handgun, a .44 Magnum bullet has a muzzle energy (KE) of 1.4 KJ (typical velocity around 430 m/s, with a projectile weight of 15.6 g), and a cross-section of 99 mm2.

So, considering ratios, the Armco-on-rally car is around 24 times harder to completely contain than a .44 Magnum bullet in a bulletproof vest.

So what about something more nasty? Well, a .30-06 Springfield M2 armour-piercing bullet weighs 10.8 g, travels at 878 m/s, providing KE of 4 KJ and a cross-section of 48 mm2. This impact is 4 times less severe than the Armco-on-rally car. The Springfield round can be stopped by standard Type IV conditioned armour.

However, this isn't really the whole story, since the Armco is a throughly unstable structure under compression. All the containment system needs to do is to present sufficient initial resistance to penetration so that the buckling limit of the Armco in longitudinal compression is exceeded. Once that happens, the Armco will buckle, and the containment system need carry no increase in load.

So, what is the buckling load of a piece of Armco? And which buckling mode will dominate - Euler-Engresser or local? What is the effective length for the calculation of buckling - the intra-support distance?

I'm afraid it is midnight and I'm disinclined to stay up for hours doing these calculations, unless somebody would like to sponsor a containment system? However, based upon my own experience, I would estimate a knock-down factor of between 10 and 20 for the Armco section, loaded by a rally car, failing in buckling, compared to the load it could otherwise carry.

That being so (and I emphasise that that is just an estimate), this would put the impact containment problem firmly into the territory somewhere between bulletproof vests and ceramic armour, and much closer to the former. On that basis, my initial estimate of a relatively lightweight solution is IMHO reasonable.

Again, this is all hypothetical - as you have said, it is unlikely anybody is going to mandate this. But I would hesitate to deem something like this "unworkable" without doing some basic calculations first to confirm that hypothesis.

[bishbash]

Interesting simulation of the crash here http://www.formula1onlive.com/2011/02/3d-simulatio...

[RDMcG]

bishbash said:

Interesting simulation of the crash here http://www.formula1onlive.com/2011/02/3d-simulatio...

That is a great piece of work.

[stuttgartmetal]

Out of ITU, of to rehab unit.

[Marcia]

stuttgartmetal said:

Out of ITU, of to rehab unit.

Good to hear!

[Satsuma]

bishbash said:

Interesting simulation of the crash here http://www.formula1onlive.com/2011/02/3d-simulatio...

interesting maybe, correct certainly not.


glad to hear the man is out of intensive care.

[rottie102]

It's amazing how all other drivers respect and/or like him :

http://www.formula1.com/news/headlines/2011/3/1178...

[dr_gn]

rottie102 said:

It's amazing how all other drivers respect and/or like him :

http://www.formula1.com/news/headlines/2011/3/1178...

Oh I don't know, it's only natural that they'd rally round him...oh, err.

[Ponk]

rottie102 said:

It's amazing how all other drivers respect and/or like him :

http://www.formula1.com/news/headlines/2011/3/1178...

Despite the fact that he's cleaned most of them out at Poker

[MotorsportTom]

dr_gn said:

Oh I don't know, it's only natural that they'd rally round him...oh, err.

[GKP]

Recent Kubica Interview.

[tim-b]

skwdenyer said:

Ok, guess which row I won't be choosing to sit in when I next fly!

[boomboompow]

GKP said:

Recent Kubica Interview.

Good to hear he's recovering well

[IanMorewood]

To sum up the interview then its ow it hurts a lot and I wont be back in a F1 car this year.

But best wishes hope he makes a full recovery.

[Shaw Tarse]

Another Kubica interview

[CurvaParabolica]

He's out of hospital: http://motortweets.com/robertkubica/news/487213

[patmahe]

Excellent news hope the recovery goes well. F1 is deinitely worse without him there.

[Jasandjules]

Great news. Let's hope he's racing in 2012 F1. He was a fit fellow to start with so I hope his recovery goes smoothly and as well as can be expected.

[indigorallye]

I went and watched testing on Friday.
I chatted to quite a few drivers/ teams as you do.
The Mini 'crews' would not stop talking, the TA 'crews' were rude, ignorant and dismissive.
I don't know why, and I don't really care.

Also, it seemed to me that the TA spectacle was absolutely ruined by the Pirelli tyres. The cars were awesome on the straights but shocking through any corner/ bend/ kink.

[andygo]

indigorallye said:

I went and watched testing on Friday.
I chatted to quite a few drivers/ teams as you do.
The Mini 'crews' would not stop talking, the TA 'crews' were rude, ignorant and dismissive.
I don't know why, and I don't really care.

Also, it seemed to me that the TA spectacle was absolutely ruined by the Pirelli tyres. The cars were awesome on the straights but shocking through any corner/ bend/ kink.

Eh? Sorry, I'm missing something here maybe?