Online tools that I built

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Tom_DAF
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Online tools that I built

Postby Tom_DAF » Wed Mar 18, 2020 11:10 am

Hi all,

As some of you already know, I'm in the process of building a business designing and building custom habitation boxes. Early stages at the moment but it's going well so far.

As part of this I'm building some free tools for self-builders that I'd like to share here. Hopefully in time I can create variations of tools that I use offline but making them accessible to anyone takes much more time so thanks in advance for your patience.

EDIT: Live list of tools created so far:
• DC Cable Size Calculator
• Solar Insolation Calculator

Other tools in the pipeline that I'm considering are:
- Thermal U-value calculator to size heaters
- Rear overhang (EU method) calculator
- Weight distribution (axle moments)
- Height, width, length limits by country

I'd love to hear some ideas for tools from members here, and hear some feedback.

Cheers,

Tom
Last edited by Tom_DAF on Mon Apr 06, 2020 3:38 pm, edited 2 times in total.

Ivan C
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Re: Online tools that I built

Postby Ivan C » Wed Mar 18, 2020 12:17 pm

Some form of correlation between power/torque and weight and the impact of weight on usability.
I had a quote from MAN for a new truck and it included (if I remember right) a % of total power required for a given gradient.
Tyre size relationship with ground pressure / footprint size at road and low pressure.
Ivan C

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Re: Online tools that I built

Postby crinklystarfish » Thu Mar 19, 2020 8:56 am

Good luck, Tom. I'm confident you'll have done some kind of cost / benefit analysis - if not, there's a tool right there!

Seriously, it'd be nice to have such tools but I'd suggest most strongly that you can justify and reference your work. There are many keyboard heroes out there...

One of the burning ones is stress analysis on chassis. People often blithely go nuts with humongous fuel tanks and suchlike. And, of course, the spectre of working out the measures needed to successfully isolate torsional stess is ever-present.

These are tricky ones to quantify, though.

As might be a Centre of Gravity calculator. At a crude level, wheels on cabs tend to help topple trucks over. Maybe if computer said no more people would grasp this.

Ivan,

The chaps over at https://www.expedition-trucks.com/ published some work on tyres / ground pressure etc. Not sure if it's still there but if not you could do much worse than going taller / wider - in that order of importance (If your gearing is suitable and your drivetrain can handle it).

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Re: Online tools that I built

Postby Tom_DAF » Thu Mar 19, 2020 9:54 am

Thank you Steve, as always some good advice.

I was very conscious of using proper sources and double checking the formulas used, I was trying to keep the page simple but I'll add those references, formulas, and constants used for peace of mind. Doing my due diligence I noticed other calculators use fudge/safety factors that are not disclosed, and even suggest cable cross sections that are almost impossible to come by.

I'm working on a chassis stress analysis for the LD T244 but that's a piece of work in itself. I don't think a generic tool is feasible as each truck is vastly different, as always people should refer to manufacturer guidelines. I used to work for an OEM and given the amount of work that goes into creating guidelines (and the engineering behind them) it is really crazy to ignore them. I've seen this a lot with 400L fuel tanks on the LD with just 2 brackets bolted directly to the chassis.

I like the idea of a centre of mass calculator for side toppling (XZ plane). Getting the data for existing centre of mass can be a challenge however. I can't find it documented for the LD T244. I'll do some napkin calcs and see if this tool is feasible.

Ivan, a max gradient calculator seems feasible if gear ratios are known, I'll look into it. So does tyre footprint. In Africa I was chatting to some mine clearing engineers and they were saying that narrow tyres (like 12") are preferred in sand over wider ones because when deflated the footprint gets longer but not wider which apparently is better. Goes against conventional wisdom.

Thanks both for the suggestions.

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Re: Online tools that I built

Postby crinklystarfish » Thu Mar 19, 2020 10:18 am

Tom_DAF wrote:Thank you Steve, as always some good advice...


You're very welcome and, for what it's worth, I have confidence in your robust approach.

Tom_DAF wrote:...I was chatting to some mine clearing engineers and they were saying that narrow tyres (like 12") are preferred in sand over wider ones because when deflated the footprint gets longer but not wider which apparently is better. Goes against conventional wisdom...


Definitely good advice, especially in their unique circumstances of clearing mines; where footprint width could easily lead to a delayed lunch.

The basic principle of length-of-footprint is established and sound; and it's why most agricultural tractors evolved huge-diameter driven wheels. It's also why I fitted 14s - the aspect ratio and inceased diameter is very useful on a number of levels, the width less so.

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Re: Online tools that I built

Postby Tom_DAF » Thu Mar 19, 2020 3:41 pm

Seriously, it'd be nice to have such tools but I'd suggest most strongly that you can justify and reference your work. There are many keyboard heroes out there...


I've updated the tool to include formulae and references. Thanks for the nudge Steve.

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Re: Online tools that I built

Postby Ivan C » Thu Mar 19, 2020 5:16 pm

Steve,
I'll pop over and take a look.
My tyre choice is made:- 425/65 on 22.5x13 one piece wheels.
I wanted higher gearing for the road, these should help a little and given the use I envisage should be a reasonable compromise.
The 4 cylinder engine might have struggled a little, but the 6 shouldn't have an issue, especially as my truck loaded will be lighter than the donor was empty.
I'mean also staying inside what MAN would have offered as options.
Very interesting comments about length of tyre footprint.
Of course ground pressure can be reduced by an increase in area, or a decrease in weight.
Tom, I'd second Steve's comments about keyboard heros.
Unfortunately many people don't actually want advice, they only want their own opinion confirmed.
Ivan C

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Re: Online tools that I built

Postby Brian-reynolds » Thu Mar 19, 2020 6:47 pm

Ivan C wrote:Unfortunately many people don't actually want advice, they only want their own opinion confirmed.
Ivan C


I like that Ivan! Not heard that before!

That so much sums up members of the T244 FaceBook group that are building "expedition trucks" (read - sheds) 10 different ways of creating cold-bridges and totally not understanding just where they are going wrong!.... not clever enough to know they are not clever....

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Re: Online tools that I built

Postby crinklystarfish » Thu Mar 19, 2020 7:13 pm

Ivan C wrote:Steve,
I'll pop over and take a look.

My tyre choice is made:- 425/65 on 22.5x13 one piece wheels.
I wanted higher gearing for the road, these should help a little and given the use I envisage should be a reasonable compromise...
Ivan C


If you're committed and the numbers work then fair play Mr C. I don't know without the benefit of measuring, pondering and researching what other options you might have but if there's anything else out there that's slightly taller and slightly narrower then I'd consider it.

It'd retain / enhance the benefits of increased traction and raising gearing, but would also roll through potholes better and give a bit more comfort. More sidewall = more suspension compliance.

As tall as the truck can take whilst not over-egging the width is the way to go.

NB Make sure you leave enough room for snowchains if ever you envisage the need.

Ivan C
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Re: Online tools that I built

Postby Ivan C » Thu Mar 19, 2020 8:03 pm

Steve - I don't think that I'd get away with any taller. It's a moot point anyway as they are already fitted.
Good point about snow chains - bought and trial fitted. I'm making the back mudguards quick (ish) release to ease fitting and wheel changing.
Brian - I think I've seen one of those on u tube, overland nomad or similar
Ivan C


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