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HDT Weight & Balance Spreadsheet ? ?


Dollytrolley

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Hi all,

 

Just killing time up here on the "cliff" watching ships, barges, tugs, Yachts, Army Corps dredges & Homeland Security patrols streak by on the Columbia River and so.............bit bored most of the time taking care of mom-in-law with chronic memory issues.......so being bored.........what about composing a HDT Weight & Bal Spreadsheet that would auto-calc truck Wt & Bal configurations and loading ? ?

 

It seems that most folks that want to consider singling a HDT seem to worry a fair amount about where the "sweet-spot" is for locating the single rear axle..........do I single .....Short....or....Mid.....or....Long and IF I do will I overload the front axle ? ? ?

 

Seems odd to me that someone has not taken the HDT by the "train-horns" and wrestled-this-simple-set-of-problems-to-the ground..........

 

Let me regress back to my stone-age-birdboy-days.........with aircraft operations it is VITAL to NOT fall too far outside the test-confirmed-Weight& Balance-limits of a given aircraft model.........obviously one would think excess weight would a problem with aircraft and to a certain extent this is true......however often exceeding too far the balance limits on a aircraft have almost certain fatal results!!

 

In concept a auto-calc Wt & Bal spreadsheet for a HDT could be fairly simple to build or..........perhaps we might be able to obtain a "factory-engineered" auto-calc spreadsheet ? ?

 

Maybe something ponder.......

 

Comments ? ?

 

Drive on...........(Watch your weight.....and....keep your balance....)

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Never happen... too many engine, transmission, axle, option, combinations. Not so simple as a factory airplane where if I even change a gauge the weight of the old and new and exactly where it is on the aircraft are all well documented. (yeah, i was think'in one day too)

 

Stekay,

 

Actually you have the concept turned around in that many aircraft are a huge headache compared to trucks........I will ex-plane later today .......after we get back from the "adventure" of taking mom-n-law to eye doc.....

 

Stay-tuned for Wt & Bal ........V1.01.001

 

Drive on........(Drive carefully to.....the eye-doc)

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DT, am going thru the same issues with my Mother. Little brother, SIL and I are tag teaming the issues, short memory, eating enough, taking pills at the correct time, thyroid eg. Dealing with cleaners, companion taking her out for a drive x2 a week. Sorting out a long term care facility.

 

I can carry on the same 2 minute discussion with her for 2 hrs.

 

This may scrap the winter trip yet.

 

I hope you have help.

 

R

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There is a spread sheet calculator out there that we used when we did our designs. I am out of town without access to our home laptop so I can't post it. I forget what we got it from as it was a few years ago. Did you check the resource guide?

 

Already done. Check the Resource Guide.

 

You mean Calculating Toter Bed Size?

 

In the Resource Guide of course

 

Star, Darrly & Mark,

 

The bed spreadsheet in the resource guide is indeed a bed-design-tool ant it seems to be adequate for bed design.

 

What I am referring to is a total-truck-Weight & Balance spreadsheet that when proper configured will return the actual weights of each axle tire patch weight for whatever the truck loading condition is at a given configuration.

 

The HDT Weight & Balance spreadsheet that I propose.......... is a totally different animal form the bed spreadsheet........

 

Drive on.........(Weighty subject......hope to not lose my balance)

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DT, am going thru the same issues with my Mother. Little brother, SIL and I are tag teaming the issues, short memory, eating enough, taking pills at the correct time, thyroid eg. Dealing with cleaners, companion taking her out for a drive x2 a week. Sorting out a long term care facility.

 

I can carry on the same 2 minute discussion with her for 2 hrs.

 

This may scrap the winter trip yet.

 

I hope you have help.

 

R

 

Thanks for the support Roger.......

 

Memory care is a real......."adventure"

 

Unfortunately mom is in the less-than-1% memory disabled population that is unable to be cared for in skilled-memory-care-facilities due to "extreme- violent / aggressive behavior"

 

We keep her in a VERY serene and low-key environment and NEVER have more than two people in the room with her since more people scare her and bring a rage that is very intense.

 

The vast majority of memory-care-workers are not often able to assist in this less than 1% population since standard memory-care mitigation is often results in "rage triggers". We have vetted and sifted a lot of memory-care workers and many truthfully decline to serve when they become aware of the task.......this is good we do not need well-intended-folks that often make care worse than better.

 

For the most part we are well versed to what it takes to provide a environment that mom is able to enjoy good times........some times things are fair..........and once in a while things get real ugly..........it's not nice to be in the 1% sometimes.........

 

Today is a pretty good day ........so far......

 

Enjoy the time with the old folks as best you can...........who knows some day we might just graduate from geezers.......to......old folks.......

 

Drive on..........(Enjoy the ride.......)

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Ok maybe I am sorta hijacking a thread that I started....... but maybe not........

 

Below is a link to a Auto-Calc engineering simple trailer spreadsheet based calculator that is similar to what I propose fot a HDT RV.

 

 

http://www.engineersedge.com/calculators/trailer-weight-balance.htm

 

Ponder on.........

 

Drive on.........(Calcs are ......kool)

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There was one several years ago. Not sure of the original author so can't give credit where due. Is this something like you're talking about.

 

NOTE: forum won't let me add as a spreadsheet (.xls) but will take a .PDF. This file has a .pdf extension but is really an .xls so open as such. Tried on the test section an it does work when opened as an .xls.

 

630-TLT.pdf

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DolleyT,

Let me see if I can explain where this approach falls apart. Picture a frame with 100" wheelbase. Now put 50lbs. directly over the front axle and 50 lbs directly over the rear axle. Let's now do another identical frame with 100lbs. exactly midway (50") between the axles. Now let's move the rear axle forward 25". See the problem with not knowing the weight distribution.

After you move the axle you can determine the result, but not accurately before... and then is too late. You really need to do the job on scales. Not easy.

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Dolly, the spread sheet that Ray posted, I think does the calculations you are thinking of. You do need to know your starting HDT axle weights and your axle locations. From there you can add weight to certain areas, move weight around and I think you can even change wheel base to see what effect the various configurations give you for axle weights. Now it does not give you individual tire weights but if you assume evenly distributed weight side to side that can be manually calculated and is only an assumption because you would have to start with individual wheel weights and most do not have that abilitity to get them easily but can get axle weights fairly easily.

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DolleyT,

Let me see if I can explain where this approach falls apart. Picture a frame with 100" wheelbase. Now put 50lbs. directly over the front axle and 50 lbs directly over the rear axle. Let's now do another identical frame with 100lbs. exactly midway (50") between the axles. Now let's move the rear axle forward 25". See the problem with not knowing the weight distribution.

After you move the axle you can determine the result, but not accurately before... and then is too late. You really need to do the job on scales. Not easy.

 

Stekay...... please help me here .........

 

The FAA would often take a moment or two to listen me to complain about my gripe-of-the-day and then they would point to the sign pinned to the wall back by the coffee machine.........the sign lettering ......."We are Unhappy.......UNTIL......You are Uhappy"

 

So......if I dropped in to the FAA Engineering section and said......."Ok boys nI've gotthe ole Blunderbird XG109 out on the ramp and ....with 100" wheelbase. Now put 50lbs. directly over the front axle and 50 lbs directly over the rear axle. Let's now do another identical air-frame with 100lbs. exactly midway (50") between the axles. Now let's move the rear axle forward 25...........and I brought the portable scales with me so that we can tramp-out in the HOT sun and get the ole Blunderbird up on the scales because........ WE can't do the math...........The FAA Engineers would all rock back in their chairs and point the the sign on the wall and then all together they would say.........."DO THE MATH......it's too hot to weigh the Bulnderbird today"..........

 

Why would math AND physics fail just because something (axle) was moved to another location??

 

Your example, is a classic example, why Weight & Balance calculators DO actually function......

 

Drive on..........(I'm happy........if you're happy)

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DolleyT,

Let me see if I can explain where this approach falls apart. Picture a frame with 100" wheelbase. Now put 50lbs. directly over the front axle and 50 lbs directly over the rear axle. Let's now do another identical frame with 100lbs. exactly midway (50") between the axles. Now let's move the rear axle forward 25". See the problem with not knowing the weight distribution.

After you move the axle you can determine the result, but not accurately before... and then is too late. You really need to do the job on scales. Not easy.

Just model the existing truck as two finite weights, one directly over the front axle, and one directly over the rear axle. If there's a new load you want to add, add that as a new object of weight X and position (using its center of gravity) Y relative to the front axle. If it's 22% of the way from front axle to rear axle, put 22% of the weight onto the rear, and 78% onto the front. If it's 110% of the way from front axle to rear axle (in other words, it hangs out behind the rear axle), put 110% of the weight onto the rear and -10% onto the front.

 

If you've got something existing that you want to relocate (maybe a fuel tank), treat it as two new loads, one with "negative weight" in the old position, one with positive weight in the new position. If you've got something new that's an odd shape, find a way to model it as multiple smaller elements; that should make it easier to guess the weight distribution within the odd-shaped object. In other words, treat the drom box as one item, the bed as another, the bed fenders as another, storage compartment contents as another, winch as another, etc.

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Dolly, the spread sheet that Ray posted, I think does the calculations you are thinking of. You do need to know your starting HDT axle weights and your axle locations. From there you can add weight to certain areas, move weight around and I think you can even change wheel base to see what effect the various configurations give you for axle weights. Now it does not give you individual tire weights but if you assume evenly distributed weight side to side that can be manually calculated and is only an assumption because you would have to start with individual wheel weights and most do not have that abilitity to get them easily but can get axle weights fairly easily.

 

Star,

 

I did down load the PDF file and converted it to a xls and played with it a bit.......

 

The math functions are somewhat hidden so it is hard to really see the "Layout" of the truck so to speak.

 

The last page of the report is fairly rich in information and so.... IF the hidden ""Layout" of the truck is close then the numbers might be close.

 

Before Computers............(....B C....) before B C we had slide-rules........(S L) and before S L we had pencil and paper........anyhow in the infinite wisdom that only the FAA has..........it was decided that aircraft had to have "Full Disclosure" of Weight & Balance AND also most aircraft HAD to have accounted Weight /Arm / Moment listings for "consumables" (Fuel, Oil, Anti-Ice fluids, .....booze, etc.) as well as seating and cargo locations.....AND other "accountable-items" (Survival-kits, flares, life-rafts etc.) So........assuming that the pilot is NOT legal to fly the ole "Blunderbird"......until a Valid Wt & Bal has been computed AND the CG & Wt fall within legal limits .........the pilot HAS to be able to fumble through the calcs with fairly normal math skills....so.....

 

The AFM (Aircraft Flight Manual) will have a Weight & Balance section with the Dataum Line and Aircraft Empty Weight and Center Gravity Location (CG)

 

The table below the will list the name of item #1 name in the first column, the 2nd column will have a space for weight in pound , Column #3 will list the Arm (Distance from the Datum Line) and Column #4 has a space to enter the computed "Moment"

 

So for example I am planted in Seat A12 and I weigh 270 lbs at arm 360" we are able to compute 270 X 360=97200 Moment

 

So to make a long story short you just add up the weight and moment columns and consult the loading graph with weight on the z scale and moment on the X scale and where the two lines hopefully your are within the acceptable envelope.........now that was simple.....right?

 

Now trucks are somewhat different than aircraft since CG is not often a desired known value as much as axle weight loads are....

 

So......in a truck you would likely like to weigh the base truck with each axle listed as a item and then using a datum line you could assign arm values and then you could using the axle weights then you could calc the moments for each axle then calc the CG location for the base truck THEN you could Calculate the CG as a Percentage of wheel base AND......THEN.... you have the basis to start ....adding.....removing items....or moving items using Wt X Arm=Moment numbers and then recalculating CG that will then be used to recalculate the percentage of wheel base mass distribution...........Simple.......right? ? ?

 

Even the lowest form of life.......... a pilot....... can do it....

 

Drive on.........(enjoy the math.....)

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As I recall.....one of the forum members was a retired Airbus factory Wt & Bal tech...........seems he has some portable scales and weighs RV's for axle / tire actual data for owners.........this chap could likely brew-up a nice universal HDT spreadsheet in a flash.....

 

Drive on.......(Calc .... with care)

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Star,

 

...

The math functions are somewhat hidden so it is hard to really see the "Layout" of the truck so to speak.

 

The last page of the report is fairly rich in information and so.... IF the hidden ""Layout" of the truck is close then the numbers might be close.....

 

If you unprotect the "Computation" tab you can now see the formulas same goes for the last tab.

 

Thankfully we are not dealing with Rockets or even airplanes, but I did launch my van through the air some 40 years ago and I did not need a slide rule or computer to do it. I just haven't figured out how the Duke boys did in all the time and I do it once and break my back in 3 places. I am glad the HDT has airride seats!

 

If we are a few pounds off I will just tell the passengers to move to another seat, just like the copilot/ stewadress tell me when I ride on those prop type puddle jumper airplanes.

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