Author Topic: M5 Stuart Light Tank  (Read 4376 times)

Offline sid pileski

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Re: M5 Stuart Light Tank
« Reply #30 on: January 19, 2021, 09:02:01 PM »
Is it just me?
I don't see any of the pictures.
I'm logged in.


Hmmmmmmm???

Sid

Online crueby

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Re: M5 Stuart Light Tank
« Reply #31 on: January 19, 2021, 09:24:25 PM »
Is it just me?
I don't see any of the pictures.
I'm logged in.


Hmmmmmmm???

Sid
Showing for me here at the moment.

Offline Admiral_dk

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Re: M5 Stuart Light Tank
« Reply #32 on: January 19, 2021, 10:14:31 PM »
I really like the layout and construction Mike  :ThumbsUp:

You get a lot less torque load on the clutches if they work @ full engine RPM - but this means that you need four two speed boxes -> no go .... wonder if it's possible to scale the modern slipper clutches down  :thinking:
They use a ramp system -> when the torque is coming from the wheel it looses the spring pressure on the plates and when it's from the engine the ramp works the other way and grips even harder on the plates ....

Still following along  :popcorn:   :cheers:

Offline Laurentic

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Re: M5 Stuart Light Tank
« Reply #33 on: January 20, 2021, 10:52:12 AM »
Interesting stuff in your explanation notes Mike - and the exploded drawing of the gearbox made things much clearer, thanks for that.

Chris

Online Vixen

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Re: M5 Stuart Light Tank
« Reply #34 on: January 20, 2021, 12:25:45 PM »

You get a lot less torque load on the clutches if they work @ full engine RPM - but this means that you need four two speed boxes -> no go .... wonder if it's possible to scale the modern slipper clutches down  :thinking:
They use a ramp system -> when the torque is coming from the wheel it looses the spring pressure on the plates and when it's from the engine the ramp works the other way and grips even harder on the plates ....

Still following along  :popcorn:   :cheers:

Thanks for your input Per.

If you study the drawing you will see the four clutches are already spinning at full engine RPM.

I am not sure how your proposed slipper clutch works or how it would help with this steering system. Do you think they could be incorporated  by slightly modifying the existing design? If a complete re-design were necessary, I would abandon the four clutch steering system altogether.

The CT1 is an interesting and clever design, (that's why I built one). However, I have since discovered, that there are much better and more suitable steering systems available for tracked vehicles. Wait and see whats in store with the next tank.... the StuG  111

Just saying.

Mike   :atcomputer:
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Admiral_dk

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Re: M5 Stuart Light Tank
« Reply #35 on: January 20, 2021, 01:00:49 PM »
You're right that I somehow missed the bit about them running at engine speed. On the other hand - if you got the two speed box installed too - you can't have all clutches running at the same speed ....

I did no suggest that you rebuild your tank (in my mind) but as you mention problems with clutch friction and that the servos have a problem with supplying a high enough pressure on the plates ...

As you clutches have a rather big similarity with motorcycle clutches - I just thought out loud ....  There is a difference though as on a motorcycle, it's springs that provide the pressure on the plates and you have a geared (lever or actual gear) action that releases them.

On the generation that is becoming the norm today, you got the slipper system. This uses the fact that for years the outside clutch-basket was made up off two parts spring loaded as a shock absorber (rotational direction). By putting a ramp on each part - you get the extra squeeze / loosening off the plates on the side that normally is 'fixed' in the previous generation. The two part described is the big gear in the primary gearing (driven directly by the gear on the crank) and the outside clutch-basket.

Online Vixen

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Re: M5 Stuart Light Tank
« Reply #36 on: January 20, 2021, 01:37:12 PM »
Hello Per

I found this illustration which shows how the slipper clutch works.



It works very much like a one way sprag clutch but with the addition of controllable manual engagement. The assist function would certainly help to lock the model tank's multi-plate clutch into full engagement.

I can see the advantage of such a clutch on a modern high power super bike. If the engine were to seize  :censored: , the back wheel 'pushes' the clutch out of engagement, so preventing the rear wheel from locking. It would disengage the clutch much faster than human reaction time. I could have done with one, years ago, when I went circuit racing. It would have saved me from the loss of a lot of skin.

Mike  :atcomputer:

Edit   During a turn the tracks of a tank can 'push' as strongly as the engine. Perhaps it would be necessary to keep the  'Assist' and eliminate the 'Slipper' function in a steering gearbox.
« Last Edit: January 20, 2021, 06:01:44 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Admiral_dk

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Re: M5 Stuart Light Tank
« Reply #37 on: January 20, 2021, 08:16:45 PM »
Oh they work fantastic without the infamous seizure .... you can see them banging down the box during heavy braking without any rear-wheel hopping or fear off other nasties - and by the way the Pro Offroaders use them too  :)    :cheers:

Offline Zephyrin

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Re: M5 Stuart Light Tank
« Reply #38 on: January 21, 2021, 07:48:09 AM »
this thread is really instructive, the model and the mechanics are awesome.
attention to mechanical solutions are impressive.
thanks to share all these knowledges.

Online Vixen

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Re: M5 Stuart Light Tank
« Reply #39 on: January 21, 2021, 03:01:17 PM »
I am pleased you like the content of this thread. Tracked vehicle design is a fascinating subject.

I too have enjoyed looking through my old photo albums, preparing this stuff and re-living an interesting journey of discovery.

Stay safe

Mike   :atcomputer:
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Online Vixen

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Re: M5 Stuart Light Tank
« Reply #40 on: January 21, 2021, 10:05:47 PM »
I've now got about as far as I can go with the development of my M5 Stuart. I have learned a great deal about the dynamics of tracked vehicle steering. Gained useful experience regarding the operation of clutch steering systems. Learned about the performance and limitations of model engine carburetors. I am now about ready for the next step, to embark on a slightly larger, all metal, model tank. Hopefully, with many improvements as a result of the lessons learnt from the Stuart

I also learned it was not necessary to use a model radial engine to replicate the full size original. Once the engine is covered up, in that big hump at the back of the tank, it is out of sight. Few casual observers can tell there is a radial engine installed, and even fewer know what a radial engine is.       They ask " Is it electric and has it got a sound system?" :facepalm: :facepalm:

The Start tank served me well, taught a lot and has given my immense pleasure and fun, but the cracks are beginning to show (literally). The plastic body shell has stress cracks radiating from all the attachment points, it's literally falling apart. (bit like me, in a way  :old: )







Before the Stuart goes into retirement, I have one more development task for it. I have heard many good reports about the 32 cc single cylinder Honda GX32 fourstroke industrial engine. It is said to be a highly reliable, well mannered little engine which should make an ideal power source for the next all-metal tank. The fuel tank hanging off the back was only a temporary arrangement






The Honda GX32 is a clean running, low revving fourstroke with pumped oil lubrication from a wet sump. It burns straight petrol (gasoline) with no added oil. It sounds sweet, not the high revving buzz of a two stroke chain saw engineand none of the evil smelling blue smoke. The engine comes equipped with a built in exhaust silencer (muffler?), a pull starter, self contained magneto ignition, Built in centrifugal clutch. perhaps the most important feature is the pumped, variable jet barrel carburetor, which gives an excellent throttle response, all the way from tick-over to full power, without the slightest hesitation.

The Honda engine is versatile, it can be installed in an upright position, as you can see here in the Stuart model, or it can be laid on side, horizontally, which will make for a much lower installed height.

This last photo shows the Stuart recon tank in it's final stage of development, running sweetly on Honda power. The Stuart served me well and paved the way towards the next tank, by demonstrating the suitability of the little Honda engine in a real tracked vehicle.





Stay Tuned, there's more to follow

Mike
« Last Edit: July 31, 2021, 12:17:49 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Admiral_dk

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Re: M5 Stuart Light Tank
« Reply #41 on: January 21, 2021, 10:50:47 PM »
I remember Honda claim that they really throw most of their immensely big (in MC Racing they are compared to NASA) R&D department into the development of this engine  :o  simply to ensure that it's virtually completely indestructible.
The reason - they use it in a huge amount of power tools they make and provide many years of warranty on + they knew that most of the customers would not treat these engines well ....

First time I see it use in a model, but it makes sense  :ThumbsUp:

Online Vixen

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Re: M5 Stuart Light Tank
« Reply #42 on: January 22, 2021, 08:57:06 PM »
The M5 Stuart light tank thread has reached the end. The petrol Powered Panzer saga now continues with the StuG 111 journey at

https://www.modelenginemaker.com/index.php/topic,10166.msg231371/topicseen.html#new

Stay safe and enjoy

Mike   :atcomputer:
« Last Edit: January 22, 2021, 09:30:53 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Dave Otto

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Re: M5 Stuart Light Tank
« Reply #43 on: January 23, 2021, 01:29:31 AM »
Thanks Mike, I have enjoyed this.  :ThumbsUp:

Dave