RV Python - Vince replies!
Discussion
Rather than continue this on the Python Brochure thread I thought it merited a new one.
As the title implies, Vince has now replied to my e-mail, and Den isn't going to like the contents.
Yes Den, the Python exists! They're laying up body No3 at the moment and are working on chassis 6 to 12, so production has well and truly started. Vince even sent some jpegs showing work in progress. And I have to say that cassis doesn't look too flimsy to me Den.
As for the heritage and the name, Vince says he bought the (by that time long dormant) Python project from Unique Autocraft in January 2001. He even had a Python on display at the 2001 Stafford Show.
The reason the 'production' RV version is so different to Unique's is that Vince reckoned the chassis was too heavy so set about effectively re-engineering the whole car, changing to BMW mechanics while he was at it, which obviously takes time.
Right then Den, over to you...
As the title implies, Vince has now replied to my e-mail, and Den isn't going to like the contents.
Yes Den, the Python exists! They're laying up body No3 at the moment and are working on chassis 6 to 12, so production has well and truly started. Vince even sent some jpegs showing work in progress. And I have to say that cassis doesn't look too flimsy to me Den.
As for the heritage and the name, Vince says he bought the (by that time long dormant) Python project from Unique Autocraft in January 2001. He even had a Python on display at the 2001 Stafford Show.
The reason the 'production' RV version is so different to Unique's is that Vince reckoned the chassis was too heavy so set about effectively re-engineering the whole car, changing to BMW mechanics while he was at it, which obviously takes time.
Right then Den, over to you...
Hi Den.
You say it's a new design, but is it? Haven't checked this with Vince, but if it still uses the original Python body (and the extended wheelbase suggests it could) then is it really a 'new' design or in fact a development of the original as claimed? Open to interpretation methinks, though you've made your interpretation clear.
As for Vince not having answered any of the substansive issues, that's possibly because he's too busy building Pythons at the moment.
Don't know why you should raise doubts about the notion of a BMW based Cobra Den, as Gardner Douglas have used a BMW V8 in one of theirs.
However, you're quite right to advise people not to part with the readies until they've seen something tangible.
I've no doubt that a tangible Python will appear at certain kit car shows next year, at which time we'll all be able to generate better informed opinions as to its worth.
And let's not forget that Filby's involvement is only with the UK marketing, not the engineering. Thank goodness...
You say it's a new design, but is it? Haven't checked this with Vince, but if it still uses the original Python body (and the extended wheelbase suggests it could) then is it really a 'new' design or in fact a development of the original as claimed? Open to interpretation methinks, though you've made your interpretation clear.
As for Vince not having answered any of the substansive issues, that's possibly because he's too busy building Pythons at the moment.
Don't know why you should raise doubts about the notion of a BMW based Cobra Den, as Gardner Douglas have used a BMW V8 in one of theirs.
However, you're quite right to advise people not to part with the readies until they've seen something tangible.
I've no doubt that a tangible Python will appear at certain kit car shows next year, at which time we'll all be able to generate better informed opinions as to its worth.
And let's not forget that Filby's involvement is only with the UK marketing, not the engineering. Thank goodness...
kitcarman said:
New mechanics, new chassis, new floor, new pedals, new steering column = new design.
So by that reasoning Den, the current Pilgrim Sumo isn't really a Pilgrim Sumo because it has new mechanics, new chassis, new floor, new pedals and new steering column compared to the original.
kitcarman said:
given that his car was advertised as being ‘back with bite’ two years ago, I’d be tempted to be critical of his rate of work. He hasn’t built one yet. For your information it takes a day to make a ladder chassis (2 days at most) and 2 man-days to make a body (4 at most).
Things sometimes take a lot longer than you expect - especially if you want to do the job right. Are you equally critical of Chris Greville-Smith and Norman Morris for the length of time it took them to get the Phantom properly into production? Didn't think so.
grahambell said:
Don't know why you should raise doubts about the notion of a BMW based Cobra Den.
kitcarman said:
I didn’t. I’ve reproduced what I’ve said again below.
KitCar said:
What Hasn’t Been Said
We’re not saying that a BMW based Cobra cannot be produced. We simply say that one hasn’t yet been produced but it is presented, in one particular magazine, as if it had. We simply wish to avoid our readers being used as unsuspecting test dummies for prototype development.
kitcarman said:
As you can read , I’ve not said it can’t be done.
Agreed Den, you've not said it CAN'T be done, but what you have said is clearly intented to raise doubts about whether it will be done or done properly. So that's still raising doubts about the notion of a BMW based Cobra
grahambell said:
And let's not forget that Filby's involvement is only with the UK marketing, not the engineering. Thank goodness...
[quote=kitcarman]You know that, do you?
Well I'm pretty sure he's not working in Vince's factory in Sri Lanka...
Tell you what Den, rather than you have to communicate with a 'go-between' I'll e-mail Vince the URL's of the relevant threads and if he's inclined (and can find the time) maybe he'll start posting here himself.
>> Edited by grahambell on Thursday 4th December 20:04
Hi Den,
My comments regarding the current and original Sumo was rather tongue in cheek (hence the winking smiley) but does make a serious point. The later Sumo is completely different in all but looks to the original, yet bears the same name. So Den, would you descibe it as a different car or a development of the original?
You say you havn't been casting aspersions on the notion of a BMW based Cobra. Well sorry Den, but on this forum you've basically done nothing but cast aspersions on the whole Python project, continually referring to it as the Monty Python.
First, you deny any Python brochure exists and even arrange for PHers to send off for one. Then, when the requested information duly arrives you say it doesn't really constitute a brochure.
You also keep stating that the car is effectively a figment of someone's imagination, and then when you're told it is in production still keep implying that it's not going to be any good.
Or at least that's the way it comes across to me, and I think many others, which combined with the amount of space your magazine devoted to having a go at Filby isn't doing you any favours Den.
Regarding the chassis, this isn't something radically new and untried, it's basically a ladderframe with a small backbone centre section added.
Can't comment on whether or not a prototype has been built and driven because I don't know.
I do however know Den that the Mk 1 Sumo I got from you had all sorts of fundamental problems from an engine mount being in the wrong place and chassis brackets that wouldn't accept what they were supposedly designed to, to the fact that the body couldn't be made to mount on the chassis without cutting and re-glassing the rear bulkhead.
Now what was that you said about mass producing before the producer had verified the design?
You keep asking who will sort out any problems that occur with a Python. Probably the same person who had to sort out the problems with my Mk 1 Sumo Den, namely the builder.
I've now e-mailed Vince the URLs of these forum pages and invited him to reply personally if he feels so inclined.
Den, we all know you have a vendetta against Filby, and maybe justifiably so as there's no doubt some of his actions have been questionable to say the least, but that doesn't mean that anything Filby has any sort of connection with automatically has to be crap.
You've repeatedly made your point at great length both here and in WK and had more than a little criticism for going over the top as a result, so maybe it's time to start adopting the 'less is more' approach to the Filby situation eh?
My comments regarding the current and original Sumo was rather tongue in cheek (hence the winking smiley) but does make a serious point. The later Sumo is completely different in all but looks to the original, yet bears the same name. So Den, would you descibe it as a different car or a development of the original?
You say you havn't been casting aspersions on the notion of a BMW based Cobra. Well sorry Den, but on this forum you've basically done nothing but cast aspersions on the whole Python project, continually referring to it as the Monty Python.
First, you deny any Python brochure exists and even arrange for PHers to send off for one. Then, when the requested information duly arrives you say it doesn't really constitute a brochure.
You also keep stating that the car is effectively a figment of someone's imagination, and then when you're told it is in production still keep implying that it's not going to be any good.
Or at least that's the way it comes across to me, and I think many others, which combined with the amount of space your magazine devoted to having a go at Filby isn't doing you any favours Den.
Regarding the chassis, this isn't something radically new and untried, it's basically a ladderframe with a small backbone centre section added.
Can't comment on whether or not a prototype has been built and driven because I don't know.
I do however know Den that the Mk 1 Sumo I got from you had all sorts of fundamental problems from an engine mount being in the wrong place and chassis brackets that wouldn't accept what they were supposedly designed to, to the fact that the body couldn't be made to mount on the chassis without cutting and re-glassing the rear bulkhead.
Now what was that you said about mass producing before the producer had verified the design?
You keep asking who will sort out any problems that occur with a Python. Probably the same person who had to sort out the problems with my Mk 1 Sumo Den, namely the builder.
I've now e-mailed Vince the URLs of these forum pages and invited him to reply personally if he feels so inclined.
Den, we all know you have a vendetta against Filby, and maybe justifiably so as there's no doubt some of his actions have been questionable to say the least, but that doesn't mean that anything Filby has any sort of connection with automatically has to be crap.
You've repeatedly made your point at great length both here and in WK and had more than a little criticism for going over the top as a result, so maybe it's time to start adopting the 'less is more' approach to the Filby situation eh?
Mr2Mike said:
I don't see any attack on Vince or even the car itself from Den's, simply a suggestion that the marketing tactics were not appropriate.
I think that constantly referring to it as the Monty Python and stating that there will be inevitable problems rates as an attack, albeit a mild one.
As for the new car or not bit - Vince bought the original Python, decided there were aspects that could be improved or updated and set about doing so. Yes, that's involved redesigning large amounts of it, but to continue my analogy, almost all of the original Cortina based Sumo was changed in the process of creating the present Granada/Jag based Sumo.
So does that make it a new car or a development of the original model? Matter of opinion I guess, but Pilgrim's current advertising suggests they see it as development.
No argument from me about the misleading advertising and self-promotion, which as far as I'm aware is entirely down to Filby and which Den was quite right to complain and warn people about.
But that's the thing - the core of the problem isn't the Python - it's Filby.
We won't be able to decide for certain if the Python is any good or not until we get to see the finished article. I think we can already come to a decision regarding Filby.
Regarding Ex-biker's question re. the BMW engined Gardner Douglas, yes, I do know this for a fact because they were building it when I was there to test the GD T70. It wasn't a 'production fit' but a one-off for a customer who wanted one.
kitcarman said:
I do however know Den that the Mk 1 Sumo I got from you had all sorts of fundamental problems from an engine mount being in the wrong place and chassis brackets that wouldn't accept what they were supposedly designed to. . . .
Now what was that you said about mass producing before the producer had verified the design?
You keep asking who will sort out any problems that occur with a Python. Probably the same person who had to sort out the problems with my Mk 1 Sumo Den, namely the builder.
Ooooocccchhhhh!
!
Graham, that was below the belt, mate!
Sorry Den, but I felt it had to be said. To be fair though you were obviously aware of the problems when I told you and were already developing the Mk 2 Sumo.
kitcarman said:
Thirdly, you’ve kindly not mentioned the very worse problem of the Sumo Mk1 which was that it’s chassis suffered a fundamental design flaw
. The same flaw, as it happens, as is evident in the new Python chassis. Not that unusual 15 years ago,
but something I had hoped was behind this industry now.
Wouldn't be referring to flex by any chance Den...? Flex has always been a problem with ladder frame chassis as they're not good torsionally. It is however possible to stiffen things up by attaching a nice rigid structure (ie. stiff bodyshell) on top. And let's not forget that one of the best respected names in the fake snake game (Dax) use a ladder frame chassis.
It of course remains to be seen how well the Python fares in this (or any other) respect.
Have had another e-mail from Vince saying that he's far too busy building Pythons to enter into any discussions here, but he intends to have a Python at the Stafford show, so let's wait and see.
Pies said:
So vince has time to e-mail you,but no time to post here personally
Well if he started posting here he'd probably feel compelled to start repsonding to every post Den makes - in which case he'd never have any time to do any work...
As for the strength of the Python's chassis, like I said, we'll have to wait and see. It doesn't actually have quite the same flaw as Den mentioned afflicted the Mk 1 Sumo chassis, because while that used standard Cortina suspension, the Python uses rocker arms with inboard coilovers, similar to the set-up used on the Stylus/Fury.
This effectively reduces the twisting loads by feeding shock loadings through the suspension into the chassis down and centrally rather than pushing a corner upwards as is the case with outboard suspension.
Consider that and the fact that Vince does have some knowledge and experience of chassis design and that could make all the difference. Couldn't it Den? Come on - be honest now. After all, your name's not Filby...
Of course whether the Python turns out to good or not will make no difference to the fact that Filby has being pulling a con job by using his magazine to give rave reviews to cars that they haven't driven just so that he can make money out of them.
As Den says, the real issue here isn't the Python, it's integrity - and the fact that Filby doesn't appear to have any.
Well I was just about to post this after writing it when I just noticed Vince has replied in person.
Doesn't affect what I was going to say though so here it is:
Den and Ferg,
Regarding the inboard suspension/rocker arm aspect, as Ferg says, there will be loadings acting upwards at the rocker arm pivot. But which way is the spring pushed when the wheel is pushed up? DOWN.
What this means is that instead of ALL the suspension loadings acting upwards in one corner and subjecting the chassis as a whole to a large torsional stress, a large part of that loading is instead acting downwards towards the centre of a crossmember which is being subjected to a <B>bending</B> stress.
Admittedly some of this bending load will be transferred by the crossmember to become torsional loads at the longitudinal chassis rails (leverage) but it'll be trying to twist them in <B>opposite</B> directions, ie. both in at the top.
Compare that to outboard suspension where the leverage effect is trying to twist both chassis rails in the <B>same</B> direction.
If you then join the two longitudinal rails by an upper crossmember that'll bear this opposing twisting in compression (the state materials are strongest in) you have a structure that will then redirect these opposing torsional loads against each other, effectively cancelling each other out.
Does that make sense? It's what's known in engineering as 'force flow'.
And Den, sorry mate, but I'm going to have to disagree with you when you say that you have not expressed views either way on the Python as you have repeatedly posted dire warnings saying the chassis will flex, there will be problems, it'll all end in tears etc.
Sound like views to me Den. Fully agree with your stance on Filby and his misleading promotion etc, but think it's unfair to start criticising a car when you don't really have anything to base a sound judgement on. It's about on par with Filby praising a car when he doesn't really have anything to base a sound judgement on.
That's why I felt compelled to start posting the counterpoint regarding the Python and contact Vince, who as you can see, has now added his own comments.
Doesn't affect what I was going to say though so here it is:
Den and Ferg,
Regarding the inboard suspension/rocker arm aspect, as Ferg says, there will be loadings acting upwards at the rocker arm pivot. But which way is the spring pushed when the wheel is pushed up? DOWN.
What this means is that instead of ALL the suspension loadings acting upwards in one corner and subjecting the chassis as a whole to a large torsional stress, a large part of that loading is instead acting downwards towards the centre of a crossmember which is being subjected to a <B>bending</B> stress.
Admittedly some of this bending load will be transferred by the crossmember to become torsional loads at the longitudinal chassis rails (leverage) but it'll be trying to twist them in <B>opposite</B> directions, ie. both in at the top.
Compare that to outboard suspension where the leverage effect is trying to twist both chassis rails in the <B>same</B> direction.
If you then join the two longitudinal rails by an upper crossmember that'll bear this opposing twisting in compression (the state materials are strongest in) you have a structure that will then redirect these opposing torsional loads against each other, effectively cancelling each other out.
Does that make sense? It's what's known in engineering as 'force flow'.
And Den, sorry mate, but I'm going to have to disagree with you when you say that you have not expressed views either way on the Python as you have repeatedly posted dire warnings saying the chassis will flex, there will be problems, it'll all end in tears etc.
Sound like views to me Den. Fully agree with your stance on Filby and his misleading promotion etc, but think it's unfair to start criticising a car when you don't really have anything to base a sound judgement on. It's about on par with Filby praising a car when he doesn't really have anything to base a sound judgement on.
That's why I felt compelled to start posting the counterpoint regarding the Python and contact Vince, who as you can see, has now added his own comments.
Hi Den,
Glad you finally admit that you've been unfair on the Python in this forum.
As for your reply to my explanation of why the Python chassis won't suffer as badly from flex as the Sumo one due to its inboard suspension:
Well Den, it's not a thin strip, it's a box section, and it's tying the longitudinal rails together at the point the suspension loads will be acting. This is completely different (and far stronger) than your old Sumo set up.
I assume you're actually referring to the lower box section running between the rails at the front of the chassis. This is broadly similar to the one you had on the Sumo, and yes, on its own would do little for torsional strength. But as I've already pointed out, it's not on its own. There's both an upper cross member and a lower one, and that makes a big difference.
Also, from the photos Vince sent of a car in build, it looks like there are additional bolted crossmembers which wouldn't be apparent from a bare chassis photo. See Den, that's the problem with making judgements when you've only got part of the picture.
Then there's:
Sorry Den but it's you that's missed the point.
We've already established that the chassis will still be subject to upward shock loadings acting at the rocker arm pivot points. But as explained, with rocker arms these upward loadings will be far less than the upward loadings hitting the same bump would produce with outboard suspension, which in turn means the torsional loadings on the chassis will be far less. Agreed Den?
My explanation of force flow should show how designing structures to feed loadings from one part of the structure through to others can help to redirect or dissipate the energy involved and so produce a structure that's better able to cope with forces acting on it.
I'll just point out here that I used to be a mechanical engineering draughtsman working on submarines, so I think I can claim to know something about this stuff.
And Vince - as he's told us - has a background in aircraft design, so he should know a lot about it too.
But of course the real proof of the Python will be in the driving.
Glad you finally admit that you've been unfair on the Python in this forum.
As for your reply to my explanation of why the Python chassis won't suffer as badly from flex as the Sumo one due to its inboard suspension:
kitcarman said:
Nope, because the only crossmember that exists is the thin strip to which I referred.
Well Den, it's not a thin strip, it's a box section, and it's tying the longitudinal rails together at the point the suspension loads will be acting. This is completely different (and far stronger) than your old Sumo set up.
I assume you're actually referring to the lower box section running between the rails at the front of the chassis. This is broadly similar to the one you had on the Sumo, and yes, on its own would do little for torsional strength. But as I've already pointed out, it's not on its own. There's both an upper cross member and a lower one, and that makes a big difference.
Also, from the photos Vince sent of a car in build, it looks like there are additional bolted crossmembers which wouldn't be apparent from a bare chassis photo. See Den, that's the problem with making judgements when you've only got part of the picture.
Then there's:
kitcarman said:
Also Ferg is right. Twist or ‘torsion’ is exerted when the upward force on one wheel is greater than that on the other wheel. The difference in these forces IS that which has to be resisted by the chassis torsional stiffness. What you are saying in your ‘cancellation’ of forces argument is that if the forces are equal there will be no twist of the chassis which is the same as saying that the chassis won’t twist PROVIDED you don’t try to twist it. The argument works but somewhat misses the point, me thinks.
Sorry Den but it's you that's missed the point.
We've already established that the chassis will still be subject to upward shock loadings acting at the rocker arm pivot points. But as explained, with rocker arms these upward loadings will be far less than the upward loadings hitting the same bump would produce with outboard suspension, which in turn means the torsional loadings on the chassis will be far less. Agreed Den?
My explanation of force flow should show how designing structures to feed loadings from one part of the structure through to others can help to redirect or dissipate the energy involved and so produce a structure that's better able to cope with forces acting on it.
I'll just point out here that I used to be a mechanical engineering draughtsman working on submarines, so I think I can claim to know something about this stuff.
And Vince - as he's told us - has a background in aircraft design, so he should know a lot about it too.
But of course the real proof of the Python will be in the driving.
Had an e-mail from Vince wondering if it was a good idea for him to post here in view of the flak he's been getting. True he's made something of a personal attack on Den, but then who was it who started casting aspersions in the first place?
As Vince's dyslexia obviously makes it difficult for him to express himself in writing he might decide not to bother any more, and I wouldn't blame him.
On a more positive note, he also sent some more jpegs, some of which show the backbone section of the chassis far more clearly than previous ones and help to back up my statement that the Python chassis won't suffer the same torsional problems the Mk1 Sumo chassis did.
But as has been said before (by several people) the proof will be in the driving.
As Vince's dyslexia obviously makes it difficult for him to express himself in writing he might decide not to bother any more, and I wouldn't blame him.
On a more positive note, he also sent some more jpegs, some of which show the backbone section of the chassis far more clearly than previous ones and help to back up my statement that the Python chassis won't suffer the same torsional problems the Mk1 Sumo chassis did.
But as has been said before (by several people) the proof will be in the driving.
jgmadkit said:
I believe Den's heart is in the right place and would probably even help Vince out with the chassis design if he would let him (I think pride might get in the way here though)
I don't think Vince needs any help with chassis design from Den.
And as for Den's claim that all his jibes against the Python have proved true, no Den they haven't, which is why I started taking issue with you and still do.
Even in your 'amended warning' you keep denying that it's a development of the original. Why - just because 'RV Dynamics had nothing to do with the original Python'. So what? Lots of kit cars have been taken over by new owners who've subsequently made updates/changes.
You also say that it uses a 'body from new moulds, as yet unchecked in respect to fit'. Wrong again Den because Vince has the original Python moulds from Unique Autocraft. They even have a little plate on them saying 'moulds property of Unique Autocraft'.
And you still insist on saying that it's 'purportedly' being made in Sri Lanka when the existence of a factory, several chassis and some bodies tends to prove that it IS being made in Sri Lanka.
As you're so damned hot on taking Filby to task for his inaccurate reporting (and justifiably so) isn't it about time you sorted out your own?
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