What's Wrong with the Ducati?

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BJ.C
3498191367204618

It's not as high as a jet sprint boat :)


 


Seriously though - the mps is the limiting factor and both Honda and Yamaha have learned that if you keep it down, your engines last a whole lot longer. So they are going long on torque and gearing and keeping rpm below the point they start ripping the oil off the walls.
Click to expand...


 


That'd be Max. piston speed, no? :) Related...kinda, which is why engine dudes might play with rod length.


 


[I know bugger all about jet sprint boats, what stroke and rpm are we talking?]
 
Dr No
3498141367200124

Moment of Inertia, Mr Phantom Shaft.


Now how about that DoE on the laydown v vertical speedway engine?

Have a shot. Forget the array, how'd you go about it?
Click to expand...


 


 


WTF!!?? MOment of inertia!!?? ....... of what?   You've lost me ....... and what are you calling DoE?
 
Dr No
3498241367215309

That'd be Max. piston speed, no? :) Related...kinda, which is why engine dudes might play with rod length.


 


[I know bugger all about jet sprint boats, what stroke and rpm are we talking?]
Click to expand...


 


Well, I was only joking... those old pushrod V8s don't reach anywhere near the MPS of a GP bike. Half the tech in modern race engines is in oils.


 


And yes, max, not mean. I couldn't be arsed getting the calculator out - I'm sure there's a website calculator out there somewhere... found one!


 


So, in a JetSprint boat, for a pushrod V8, RPM is ridiculously high... they are up there with some drag cars.


 


The engine rules are funny - they have minimum displacement, rather than maximum. For 'Super Boats', they have to be normally-aspirated 6.5L+ V8s, for turbo/supercharged, 3.8L+ - usually alloy Chevies. For the turbos, usually. 6,500-7,500 rpm is normal, but in the final they bang the methanol in in buckets and turn the wick right up. I have heard talk of 8,000+


 


I'm  fan of, not involved in, Jet Sprinting, so no expert, but I have heard of diminished returns for higher RPM as it just causes the jet impeller to cavitate.


 


So, a 3.8L V8 at 7,500rpm with a stroke of around 3' (give or take a hundredth), you are talking 19 metres/sec Mean P.S.


 


The Desmosedici has a bore of 86mm and a stroke of 42.5mm, so to reach the same M.P.S. would be doing around 13,500. No idea what the factory bikes are doing - don't have the data, but using the max bore of 81mm, they can't have a stroke of greater than 48.5mm. To reach the same MPS they only need to be putting along at 12,000RPM... 


 


But... the size and weight of the big end, conrod, piston on a 3.8L V8 is significantly more than that of a 1000cc V4 GP bike. That being said, the V8 is getting around 1,200-1,400HP, not more than the GP bike (if you quadruple the bike's HP).
 
BarryMachine
3498281367225809

 

 

WTF!!?? MOment of inertia!!?? ....... of what?   You've lost me ....... and what are you calling DoE?
Click to expand...



Stop obfuscating.

Have the balls to answer the question. I've framed it twice.
 
BJ.C
3498301367226006

 

Well, I was only joking... those old pushrod V8s don't reach anywhere near the MPS of a GP bike. Half the tech in modern race engines is in oils.

 

And yes, max, not mean. I couldn't be arsed getting the calculator out - I'm sure there's a website calculator out there somewhere... found one!

 

So, in a JetSprint boat, for a pushrod V8, RPM is ridiculously high... they are up there with some drag cars.

 

The engine rules are funny - they have minimum displacement, rather than maximum. For 'Super Boats', they have to be normally-aspirated 6.5L+ V8s, for turbo/supercharged, 3.8L+ - usually alloy Chevies. For the turbos, usually. 6,500-7,500 rpm is normal, but in the final they bang the methanol in in buckets and turn the wick right up. I have heard talk of 8,000+

 

I'm  fan of, not involved in, Jet Sprinting, so no expert, but I have heard of diminished returns for higher RPM as it just causes the jet impeller to cavitate.

 

So, a 3.8L V8 at 7,500rpm with a stroke of around 3' (give or take a hundredth), you are talking 19 metres/sec Mean P.S.

 

The Desmosedici has a bore of 86mm and a stroke of 42.5mm, so to reach the same M.P.S. would be doing around 13,500. No idea what the factory bikes are doing - don't have the data, but using the max bore of 81mm, they can't have a stroke of greater than 48.5mm. To reach the same MPS they only need to be putting along at 12,000RPM... 

 

But... the size and weight of the big end, conrod, piston on a 3.8L V8 is significantly more than that of a 1000cc V4 GP bike. That being said, the V8 is getting around 1,200-1,400HP, not more than the GP bike (if you quadruple the bike's HP).
Click to expand...
As a nerdy exercise compare the max and mean piston

speeds of that Duke. Assume a max rpm of say 18000. And for the max piston speed a rod length of 100mm (too short, but this is an exercise...) and then say, 150mm.


And for another exercise; Mr Phantom Shaft's example of a Jawa 500, with a square bore and stroke...the factory ones went to 13000rpm...mean piston speed = eyeopener.
 
I ignored rod length and replaced it with stroke for MPS ;) (and my wife says a rod length of 100mm is just skyting... ;)) 


 


to get max piston speed you need rpm, stroke and rod. 


 


At 18k, the mean piston speed is 60M/sec. Which may not be achievable in the real world.


 


The Jawa, if square, would have a bore and stroke of 86mm. The MPS would be just over 37M/sec, so quite a bit more than the V8 and way more than the Desmosedici...  as you say, an eye-opener.


 


Just shows, every-meeting tear-downs and a diet of Caster Oil does a whole lot to your ability to rev to the ....... sky!


 


As a comparison, my RM500 had 88.5 x 80 and revved to about 10k with a Heron pipe which gives it an MPS of 26 or so... and that had a tear down every race, with new rings and a hone as it needed. Nothing like the care lavished on a factory Jawa which in World Speedway can get a full overhaul between races.
 
Dr No
3498431367230635

Stop obfuscating.

Have the balls to answer the question. I've framed it twice.
Click to expand...


 


I'm not ......... you just have no idea of what I'm suggesting and asking.
 
BJ.C
3498301367226006

Well, I was only joking... those old pushrod V8s don't reach anywhere near the MPS of a GP bike. Half the tech in modern race engines is in oils.


 


And yes, max, not mean. I couldn't be arsed getting the calculator out - I'm sure there's a website calculator out there somewhere... found one!


 


So, in a JetSprint boat, for a pushrod V8, RPM is ridiculously high... they are up there with some drag cars.


 


The engine rules are funny - they have minimum displacement, rather than maximum. For 'Super Boats', they have to be normally-aspirated 6.5L+ V8s, for turbo/supercharged, 3.8L+ - usually alloy Chevies. For the turbos, usually. 6,500-7,500 rpm is normal, but in the final they bang the methanol in in buckets and turn the wick right up. I have heard talk of 8,000+


 


I'm  fan of, not involved in, Jet Sprinting, so no expert, but I have heard of diminished returns for higher RPM as it just causes the jet impeller to cavitate.


 


So, a 3.8L V8 at 7,500rpm with a stroke of around 3' (give or take a hundredth), you are talking 19 metres/sec Mean P.S.


 


The Desmosedici has a bore of 86mm and a stroke of 42.5mm, so to reach the same M.P.S. would be doing around 13,500. No idea what the factory bikes are doing - don't have the data, but using the max bore of 81mm, they can't have a stroke of greater than 48.5mm. To reach the same MPS they only need to be putting along at 12,000RPM... 


 


But... the size and weight of the big end, conrod, piston on a 3.8L V8 is significantly more than that of a 1000cc V4 GP bike. That being said, the V8 is getting around 1,200-1,400HP, not more than the GP bike (if you quadruple the bike's HP).
Click to expand...


 


Hey BJ, if you like Jet Sprint boats, check out this vid.


Amazing crash....
http://www.facebook.com/photo.php?v=428392960590050
 
BarryMachine
3499001367281019

I'm not ......... you just have no idea of what I'm suggesting and asking.
Click to expand...


 


Oh, I do. I do.


 


I think it's now reasonable to add the fact that you have Phantom Balls to accompany your Phantom Shaft.




Thus, I'll return to treating your favourite subject as I used to, it's more informative and fun:




 


Variegated Scrotum Growths.
 
Dr No
3499041367286671

Oh, I do. I do.


 


I think it's now reasonable to add the fact that you have Phantom Balls to accompany your Phantom Shaft.




Thus, I'll return to treating your favourite subject as I used to, it's more informative and fun:




 


Variegated Scrotum Growths.
Click to expand...


 


Ok what is what you are calling DoE?
 
Nuts
3499031367286366

Hey BJ, if you like Jet Sprint boats, check out this vid.


Amazing crash....
http://www.facebook.com/photo.php?v=428392960590050
Click to expand...


 


It'll buff out >.<


 


That's what happens when Australians try to beat the Kiwi's... we really need to leave boats alone.


 


Mick Carroll is an awesome pilot though (and now he can claim aerobatics!). He's from South Australia... knowing which way is up was never a strong point with the Churchies.


 


I've watched Jet Sprint all over the world and no-one does it like the Kiwi's, though. We might win the odd race here or there, but those South Island boys are just ridiculous on 4" of water. That being said, this is Nathan Pretty (former Aus speedway champ) getting second in the world champs last year in NZ - so we're not complete chumps :)


 


http://www.youtube.com/watch?v=meU6xIpqjKQ
 
BJ.C
3498301367226006

Well, I was only joking... those old pushrod V8s don't reach anywhere near the MPS of a GP bike. Half the tech in modern race engines is in oils.


 
...


 


The Desmosedici has a bore of 86mm and a stroke of 42.5mm, so to reach the same M.P.S. would be doing around 13,500. No idea what the factory bikes are doing - don't have the data, but using the max bore of 81mm, they can't have a stroke of greater than 48.5mm. To reach the same MPS they only need to be putting along at 12,000RPM... 
Click to expand...


 


FWIW,


 


Observed max .... points


 


Honda ~17,000  (17K ECU limiter.)


Yam ~16,500 (16,5K ECU limiter.)


Duc ~17,800 (2012 bike.  No '13 data yet.) (Hard limit=?)


No current CRT data.
 
The only observed max .... points for me are Spies and Hayden's riding... I can absolve Smith - he's a newbie.
 
BarryMachine
3499091367301291

Ok what is what you are calling DoE?
Click to expand...


Design of Experiments.


 


A rough precis is that in an experiment we are trying to ascertain the affect on the response variables (outputs) of deliberately changing one or more input variables.  DoE is a statistical approach to determining the objectives of the experiment and hence choosing the inputs to vary.
 
He knows more than Ducati's engineers.

But now you've explained it. Let's see him apply it. As I wrote: forget the arrays, just put up the inputs.

Verify Statistical Groups?
 
yamaka46
3504391367658278

Design of Experiments.


 


A rough precis is that in an experiment we are trying to ascertain the affect on the response variables (outputs) of deliberately changing one or more input variables.  DoE is a statistical approach to determining the objectives of the experiment and hence choosing the inputs to vary.
Click to expand...


 


Well thank you.


 


Can't say I remember that as "metalanguage" though the ideology was the same.


 


Was DrN suggesting they change CoG and cant the engine back for lessening of VSG? CoG is just a relatively static ( constant ) ( apart from say fuel loss etc. ) variable, and easily adjustable. Matter of fact I wondered when the change in Min weight occurred at the beginning of 2012 whether it was a result of Ducati's testing that cuased them to perhaps run extra ballast to try and reposition there CoG . In any case none of that has worked.


 


The problem has been described as a vibration at the front that renders the front unpredictable. Whatever they have is causing a change in the centroid ( not CoG ) of turning of the bike. A "mystery" varying shift of that centroid would explain what the riders are saying, A VSG attempting to straighten ( stabilise longitudinally ) would explain that.


 


And thence back to the discussion ......... DoE ( as you call it ) is precisely what I have been going on to ascertain the cure for the Ducati.


ie. Ducati have changed so much:


 


Several frames constructions ( tough some folk still blame this.


CoG ....... :rolleyes: these aren't "showroom bikes" they can be fiddled with so easily ....... to suggest Ducati haen't tested this is ludicrous.


Engine tilted back ........ to some extent as ( supposedly ) Ducati have tried that.


Tyres ........


 


All ( and more ) to no avail, ergo its something that is a "mystery" to them


 


VSG's are a mystery!! whats wrong with that!! :lol: :lol: :lol:


 


 


Until such time as they produce a test and negative result for the affect of VSG, and given that it would be a noticeable characteristic of say a Duc compared to a Yam engine, I feel I can declare ...... Its the VSG!
 

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