"Motor racing is dangerous..."
Discussion
A friend I was visiting to collect some blanks he'd had cut for the DVA lift at TDC dial gauge supports told me today about a blow-up on track here not so long ago.
We'd been discussing dry sump pumps as I have a problem with the DS system on my Caterham....oil temperatures seem to be surprisingly low.
This guy has built and raced a 260bhp Caterham over the last 28 years and is a very well-known authority on Caterham competition and engineering.
Note...NOT some clot I bumped into "down the pub".
He has had problems with the pumps and warned me to check clearances on mine periodically.
He was racing at Spa, he was at high revs, when without any warning the motor grenaded.
Big 'bang' and he saw shrapnel, oil cloud and general mayhem, but had a very clear image of a piston exiting right, on a low trajectory, about level with the marshalling post!
Checking later, it passed within 6' of a marshall, and at such a pace that it'd have been [metaphorically speaking] ' like being hit by a cannonball. [/metaphorically speaking]..would very likely have been fatal, he reckoned, had it hit someone in the head.
It went through the crankcase and had no problem whipping through the alu skin of the Caterham!
We'd been discussing dry sump pumps as I have a problem with the DS system on my Caterham....oil temperatures seem to be surprisingly low.
This guy has built and raced a 260bhp Caterham over the last 28 years and is a very well-known authority on Caterham competition and engineering.
Note...NOT some clot I bumped into "down the pub".
He has had problems with the pumps and warned me to check clearances on mine periodically.
He was racing at Spa, he was at high revs, when without any warning the motor grenaded.
Big 'bang' and he saw shrapnel, oil cloud and general mayhem, but had a very clear image of a piston exiting right, on a low trajectory, about level with the marshalling post!
Checking later, it passed within 6' of a marshall, and at such a pace that it'd have been [metaphorically speaking] ' like being hit by a cannonball. [/metaphorically speaking]..would very likely have been fatal, he reckoned, had it hit someone in the head.
It went through the crankcase and had no problem whipping through the alu skin of the Caterham!
Edited by unclefester on Sunday 18th June 19:24
"Posting BS on the internet is dangerous..."
I'm not sure what prompted this thread, but it needs a bit of a maths reality check.
It was a Caterham, so reasonably safe to assume a 4 cylinder something between 1.3 and 2.3l in size.
Stroke would probably be no more than 90mm.
Max RPM around 8000
So, max piston speed would be about 24 m\s (53.6 mph). That's before its somehow had it's natural path altered by nearly 90 degrees, passed through (at very least) several mm of steel and ali in the block, 1mm of ali sheet (although if it went through the sideskin I'm not sure how it ever got as far as the edge of the track) and several feet of air (pistons aren't very aerodynamic).
Not exactly a cannonball....
I'm not sure what prompted this thread, but it needs a bit of a maths reality check.
It was a Caterham, so reasonably safe to assume a 4 cylinder something between 1.3 and 2.3l in size.
Stroke would probably be no more than 90mm.
Max RPM around 8000
So, max piston speed would be about 24 m\s (53.6 mph). That's before its somehow had it's natural path altered by nearly 90 degrees, passed through (at very least) several mm of steel and ali in the block, 1mm of ali sheet (although if it went through the sideskin I'm not sure how it ever got as far as the edge of the track) and several feet of air (pistons aren't very aerodynamic).
Not exactly a cannonball....
sfaulds said:
"Posting BS on the internet is dangerous..."
I'm not sure what prompted this thread, but it needs a bit of a maths reality check.
It was a Caterham, so reasonably safe to assume a 4 cylinder something between 1.3 and 2.3l in size.
Stroke would probably be no more than 90mm.
Max RPM around 8000
So, max piston speed would be about 24 m\s (53.6 mph). That's before its somehow had it's natural path altered by nearly 90 degrees, passed through (at very least) several mm of steel and ali in the block, 1mm of ali sheet (although if it went through the sideskin I'm not sure how it ever got as far as the edge of the track) and several feet of air (pistons aren't very aerodynamic).
Not exactly a cannonball....
+1I'm not sure what prompted this thread, but it needs a bit of a maths reality check.
It was a Caterham, so reasonably safe to assume a 4 cylinder something between 1.3 and 2.3l in size.
Stroke would probably be no more than 90mm.
Max RPM around 8000
So, max piston speed would be about 24 m\s (53.6 mph). That's before its somehow had it's natural path altered by nearly 90 degrees, passed through (at very least) several mm of steel and ali in the block, 1mm of ali sheet (although if it went through the sideskin I'm not sure how it ever got as far as the edge of the track) and several feet of air (pistons aren't very aerodynamic).
Not exactly a cannonball....
The ops post seems to be a work of fiction and/or massive over inflation of the facts I would think. Certainly don't recall seeing any mention in the MSA News or Scrutineering Bulletin on any such incident.
300bhp/ton said:
sfaulds said:
"Posting BS on the internet is dangerous..."
I'm not sure what prompted this thread, but it needs a bit of a maths reality check.
It was a Caterham, so reasonably safe to assume a 4 cylinder something between 1.3 and 2.3l in size.
Stroke would probably be no more than 90mm.
Max RPM around 8000
So, max piston speed would be about 24 m\s (53.6 mph). That's before its somehow had it's natural path altered by nearly 90 degrees, passed through (at very least) several mm of steel and ali in the block, 1mm of ali sheet (although if it went through the sideskin I'm not sure how it ever got as far as the edge of the track) and several feet of air (pistons aren't very aerodynamic).
Not exactly a cannonball....
+1I'm not sure what prompted this thread, but it needs a bit of a maths reality check.
It was a Caterham, so reasonably safe to assume a 4 cylinder something between 1.3 and 2.3l in size.
Stroke would probably be no more than 90mm.
Max RPM around 8000
So, max piston speed would be about 24 m\s (53.6 mph). That's before its somehow had it's natural path altered by nearly 90 degrees, passed through (at very least) several mm of steel and ali in the block, 1mm of ali sheet (although if it went through the sideskin I'm not sure how it ever got as far as the edge of the track) and several feet of air (pistons aren't very aerodynamic).
Not exactly a cannonball....
The ops post seems to be a work of fiction and/or massive over inflation of the facts I would think. Certainly don't recall seeing any mention in the MSA News or Scrutineering Bulletin on any such incident.
t' and fictional/massive inflation of the facts, based on zero actual knowledge of the incident, as admitted, nor first hand experience.One might say "Petty viciousness caused by alchohol or hangover"
Tough, you are wrong, I reported the incident exactly as it happened, as repeated to me yesterday by the engineer and designer who was driving the car at the time.
I have no axe to grind, but I don't like being accused of lying....so before you jump to ignorant conclusions, try thinking a little about how a calculation based on nothing but piston speed might perhaps be wildly out...
You have doubtless heard of 'slingshot effect' as used by NASA?
Consider....the blowup was found to have been caused by the Titan DS pump having suddenly lost the plot, which caused a big end to weld itself to the crank journal.
The crank was turning at over 8k....
I'm sure the posters of the above two comments would enjoy standing facing a piston trailing part of a conrod fired at their heads at a speed to be determined by the forces of physics...who knows what speed it was doing, my friend said it "would be like being hit by a cannonball..."
He didn't specify its actual speed, as he had no way of knowing it.... OK?
Edited by unclefester on Sunday 18th June 17:14
unclefester said:
I have no axe to grind, but I don't like being accused of lying....
No one is saying a piston didn't or couldn't escape, just that the piston speed is already an order of magnitude less than a cannonball ( 400+ meters/second) whilst it's still within the engine, let alone after punching through the block and the alloy skin.Thanks, I'm aware of ballistics speeds, plus a cannonball is rather heavier than a piston!
I was quoting the driver's own words. I've just spoken with him on the phone, he will send pix taken showing the damage.
I discovered something I didn't know, the Swindon tuned VX engine does indeed have a cast iron block, not alloy, and he further stated that he was right on the edge of the track by the marshaling post, so whatever it was that punched a hole in the side skin didn't have far to go before contacting something, human or otherwise.
The piston was not found, so it clearly flew some considerable way.
No trace of the missing piston was ever found inside the engine...
The point he was making was that a random event, not caused by pilot error, could have injured a marshal
"Like a cannonball" is often used as metaphor...FFS!
I was quoting the driver's own words. I've just spoken with him on the phone, he will send pix taken showing the damage.
I discovered something I didn't know, the Swindon tuned VX engine does indeed have a cast iron block, not alloy, and he further stated that he was right on the edge of the track by the marshaling post, so whatever it was that punched a hole in the side skin didn't have far to go before contacting something, human or otherwise.
The piston was not found, so it clearly flew some considerable way.
No trace of the missing piston was ever found inside the engine...
The point he was making was that a random event, not caused by pilot error, could have injured a marshal
"Like a cannonball" is often used as metaphor...FFS!
Edited by unclefester on Sunday 18th June 17:16
Still sounds highly unlikely and exaggerated. You're saying a piston shot off, never to be found, in a direction perpendicular to that in which it was originally travelling, passing through a CI block and an aluminium panel on the way? 
Possible I suppose but very unlikely.
BTW, do you know what the 'slingshot effect' is? I'm at a loss to understand it's relevance.
Possible I suppose but very unlikely.
BTW, do you know what the 'slingshot effect' is? I'm at a loss to understand it's relevance.
Slingshot effect as used by Nasa means the use of the gravity-well to accelerate the object entering it at a tangent, so it leaves faster than it enters.
Discus throwers use this simple centrifugal method as it means the discus goes further, faster, than they could throw it otherwise...
It's basically centrifugal force as in a spinning engine.
In this case the engine was rated to hard cut at 8250rpm.
I haven't seen the photos, so it's hard to see how a piston could have been exiting under centrifugal assistance unless the case had somehow been opened through through 360° and done one or more revolutions with the big end welded to the crank....all I can say is my post is a 100% accurate report of what I was told, and the person concerned is highly respected and not known for inventing stories...
Possibly the rod snapped, then the spinning crank somehow batted the dropped piston/parts out the side next time it came around.
Discus throwers use this simple centrifugal method as it means the discus goes further, faster, than they could throw it otherwise...
It's basically centrifugal force as in a spinning engine.
In this case the engine was rated to hard cut at 8250rpm.
I haven't seen the photos, so it's hard to see how a piston could have been exiting under centrifugal assistance unless the case had somehow been opened through through 360° and done one or more revolutions with the big end welded to the crank....all I can say is my post is a 100% accurate report of what I was told, and the person concerned is highly respected and not known for inventing stories...
Possibly the rod snapped, then the spinning crank somehow batted the dropped piston/parts out the side next time it came around.
Edited by unclefester on Sunday 18th June 17:18
I am not an expert, but it seems to me that the forces acting on an aluminium piston that are great enough to break the steel conrod connecting it to the crank must be orders of magnitude higher than those it was designed to withstand.
I am happy to accept the description given without question, and look forward to seeing the photos. Shame the internet makes people so cynical
I am happy to accept the description given without question, and look forward to seeing the photos. Shame the internet makes people so cynical
downsman said:
I am not an expert, but it seems to me that the forces acting on an aluminium piston that are great enough to break the steel conrod connecting it to the crank must be orders of magnitude higher than those it was designed to withstand.
I am happy to accept the description given without question, and look forward to seeing the photos. Shame the internet makes people so cynical
Thanks, I am inclined to agree! I am happy to accept the description given without question, and look forward to seeing the photos. Shame the internet makes people so cynical
Doncha just love keyboard warriors....
I can only assume that the effect was due to the rotational speed and inertia of the crank, otherwise I admit the whole thing sounds unlikely.
The unfortunate driver hasn't yet located the pix, and wants no obvious identifying company stickers visible....whether he trusts my PS skills (or whether he can find them) is another thing entirely.
I think the reason for the cynical response is more to do with the fact that those with experience in these matters know better. Stuart, in particular, has a great deal of racing engine experience and probably a few un-contained failures too.
The truth is that pistons accelerate to from 0mph to 50mph, and back to 0mph in the space of 100 mm or so, and are subject to considerable acceleration forces. BUT they do not go that fast, and are often moving slower than the car itself. Perhaps the piston got thrown from the car, but in terms of the OP description, the story just doesn't add up to the engineering geeks I'm afraid.
The truth is that pistons accelerate to from 0mph to 50mph, and back to 0mph in the space of 100 mm or so, and are subject to considerable acceleration forces. BUT they do not go that fast, and are often moving slower than the car itself. Perhaps the piston got thrown from the car, but in terms of the OP description, the story just doesn't add up to the engineering geeks I'm afraid.
DCL said:
I think the reason for the cynical response is more to do with the fact that those with experience in these matters know better. Stuart, in particular, has a great deal of racing engine experience and probably a few un-contained failures too.
The truth is that pistons accelerate to from 0mph to 50mph, and back to 0mph in the space of 100 mm or so, and are subject to considerable acceleration forces. BUT they do not go that fast, and are often moving slower than the car itself. Perhaps the piston got thrown from the car, but in terms of the OP description, the story just doesn't add up to the engineering geeks I'm afraid.
They may think they "know better" but here's a chance for them to learn something new.The truth is that pistons accelerate to from 0mph to 50mph, and back to 0mph in the space of 100 mm or so, and are subject to considerable acceleration forces. BUT they do not go that fast, and are often moving slower than the car itself. Perhaps the piston got thrown from the car, but in terms of the OP description, the story just doesn't add up to the engineering geeks I'm afraid.
Has anyone here actually tried firing an alu forged piston through whatever wall thickness of cast iron is in a VX block, and then through the alu skin of a Caterham? Measuring speed and trajectory?
With the conrod stub welded to the journal?
Calculated the effect of a crank journal smacking a piston lodged in the crankcase, while turning at 8000 rpm?
I very much doubt it.
I also think the very well known driver(engineer) of this car, who has been racing for 30 years or so, would tend to be believed if he was explaining what happened, which he himself thought was pretty odd, but I was the person he told about it.
if people on here, whatever their engineering background, choose to disbelieve what I've posted due to preconceived ideas and received wisdom, and without knowing anything about me as a source, that's up to them.
Science, in the form of the French Academie des Sciences, claimed that people who had direct experience of meteorites falling to earth loftily stated "These people are mistaken, lying or fabulating.
It is clearly impossible for stones to fall from the skies, as there are no stones in the sky."
Yeah, right!
Edited by unclefester on Sunday 18th June 17:24
This is what a piston looks like when it departs the block. This one departed the block on a 'slingshot' after frailling around (much as you described) together with several other items, none of which made it further than the side of the track. This is not top fuel dragster racing and there is no magical store of energy that fires things at high speed when an engine lets go. It is all rotational inertia and that has been covered above.
Edited by DCL on Sunday 18th June 15:10
Hard to see that one being reusable!
I just spoke with my buddy here again, it happened at Spa, he thinks probably 2007, he was very close to the Marshall post, but as I said, the piston, assuming that is what it was, was never found, but was certainly not inside the car or the remains of the engine.
I don't see any point in bandying estimated velocity calcs around on here, I'm merely reporting the facts as presented.
Stones do indeed fall from the sky....
I just spoke with my buddy here again, it happened at Spa, he thinks probably 2007, he was very close to the Marshall post, but as I said, the piston, assuming that is what it was, was never found, but was certainly not inside the car or the remains of the engine.
I don't see any point in bandying estimated velocity calcs around on here, I'm merely reporting the facts as presented.
Stones do indeed fall from the sky....
Edited by unclefester on Sunday 18th June 17:26
FFS - can someone please explain how an engine seizing (welding the rod to the crank) speeds up the internals?
Let's face it, a bloke down the pub told you a fairy tale, and you decided to post it on the internet. I suggest you learnt when to put down the spade and walk away from the hole.
Let's face it, a bloke down the pub told you a fairy tale, and you decided to post it on the internet. I suggest you learnt when to put down the spade and walk away from the hole.
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