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Old 01-19-2016, 01:48 PM   #21
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Gotta wonder if any math gurus here could run some side loading numbers on that tall a unit. It's not the distance between the wheels front to rear that would concern be...but side to side. There must be a way to calculate how much wind load it would take to topple a rig that tall. And given the number of tractor/trailer rigs I have seen flipped over...I'm guessing it really doesn't take all that much.
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Old 01-19-2016, 04:31 PM   #22
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Some questions, in no particular order:

With the way you've cut the chassis to get the lift, how do you plan on rebuilding the ribs?

Have you taken into account the single plane of stress caused by making a straight cut?

Is aluminum sheet a metal of convenience, or is there a specific reason for it?

How are you planning on fastening the skin together, especially if it's different metals that can have galvanic reaction with each other?

What specific things (other than being able to play basketball - ha!) inside the bus do you desire that high of a lift?

Do you plan on a lot of driving, or mostly leave it parked from one place to the next?

Ok, observations, again no particular order:

I think unless you've got a specific use for that height, my seat-of-pants engineering guess thinks that you're too high for that chassis. The school bus chassis is designed to be TALL - from the ground to the floor. This way it lifts the passengers above most collision points with the passenger compartment with normal vehicles by being tall on the frame. So, the primary engineered goal of a school bus is safety, not convenience.

Many other large/tall coaches are a lattice space frame with a low floor between the wheels. This affords the ability to go down before you go up. Even still, the tall coaches are pretty light on top - fiberglass roof, not a lot of structure except glass and the steel frame structure. A school bus with solid steel sheeting across the roof and frame spars spaced every 16" on average is pretty heavy.

Pushing that mass up higher will have a much greater effect when weight transfer occurs as you're driving. If you're planning on short infrequent drives, I don't think the height will be a big deal - it'll survive but I think it would be a white knuckle ride when there's sidewind with that large of a vehicle. The combination of the sail effect plus the top mass of a dynamic vehicle would be interesting.

I calculated an 18" raise the BB 40' AARE that I have as giving an 12-14% (~10% tolerance) increase in lateral (side to side) mass transfer over the factory height. As a reference, this effectively translated into 1" of extra "heel" as measured from the highest point of the vehicle to the outside of a 100' radius while traveling at 15 mph.

This was calculated attempting to take into account things such as spring rate capacity of the suspension and damping of shocks. I would love to instrument a vehicle and test this.

This translates into varying amounts of side forces depending on a turn radius * vehicle speed over time.

A way to think of this process:

If you have a given constant for lateral acceleration (N) for a given rate of change over a given time, this will translate to a real world force on the chassis and tires.

Adjusting the moment arm will cause (N) to increase by some amount, based on the amount of mass moment arm you've raised your vehicle.

This could cause things like unintended oscillations at speed when changing lanes, or unacceptable lean characteristics in slower speed maneuvering. The calcs I ended up with for the above BB AARE 18" lift were acceptable tolerance - no more than if all the kids were standing instead of sitting the bus while underway vs. sitting down.

If I were in your shoes I'd be trying to figure out what potential real change you have by lifting an additional three feet will do to the dynamics.

As for the metal choice for the sides, I'd really suggest keeping like-kind where you can. I know Vlad used aluminum sheeting on skirt and pop-outs, but to be honest, the areas where he was adding the sheeting was not as structural as the steel framework he first built, then attached the skin to. The sheeting that gets re-riveted between the body hoops and overlapping other sheets will transfer a lot of stresses to the other hoops on the vehicle.

I'm not so sure that aluminum sheet would be the best choice, simply because it doesn't have as much "fudge factor" as steel does. In an aircraft, things are engineered to a significant degree, and operating conditions are logged and controlled to a high degree.

Ground vehicles not so much. A grumman olson panel van with aluminum sides is very much overbuilt, but also has like-kind materials throughout the vehicle body. I'm not saying they're the same, and I'm not saying aluminum won't work, but I am saying that the longevity of the solution may not be acceptable.

This is all based on a perception that a bus will be driven a lot or without undue concern, and like I mentioned earlier - if it's just going to move from site to site and sit most of the time, I don't really see anything wrong with your approach.

You should be placing high mass items such as waste water, fresh water, and batteries in such a way that when your construction is complete, you have loaded the axles properly. If you have a 13.5k capacity front axle and a 22.5k capacity rear, I'd be wanting to ensure that I've biased my weight towards the rear a little bit, and give a corresponding percentage of capacity headroom for each. This should ensure deviations from the static loading weight (empty vs full tanks, people, cargo, etc) are never overloading one of the axles in operation.

Take my advice with a grain of salt, it's free, etc. I've only built one bus in my life so far. I have however built a number of large offroad trucks, and deal with weird thorny math issues and simulation of these sorts of things as a hobby.


tl;dr Don't use aluminum - get some electroplated sheet steel. Don't go higher than 24" of roof lift.

Quote:
Originally Posted by zoomy View Post
Hadn't really taken moment arm in to considerate but it is a pusher so the wheels are set back pretty far, I would have to think the axis angle would be similer to a norman height front engine.

Do you have any thoughts on that, suspention, or weight placement. My photo bucket is giving me greif so pics arnt up to date but I'm about to skin and water tank placement will be in the next month. I'm not sure if I want it closer to the front or the rear. I have 10' of under storage to play with and at 100 gallons thats 800lbs I have to favor the front with, but that could cause more stress by hanging 800 lbs from the middle of the chassis
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Old 01-21-2016, 01:16 AM   #23
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Some questions, in no particular order:

Q. With the way you've cut the chassis to get the lift, how do you plan on rebuilding the ribs?

A. Had a sheet metal company bend ribs slightly taller so they would fit over but share the same flange plain ill have pics later to show. Then they where attached with 22 3/8"plug welds



Q. Have you taken into account the single plane of stress caused by making a straight cut?

A. The skin, the ribs, or both? No i havent but there is some other strengthening items I put in so im not too conserned about THAT stress


Q. Is aluminum sheet a metal of convenience, or is there a specific reason for it?

A. Convenience and weight. Already have it and dont want to buy all new.



Q. How are you planning on fastening the skin together, especially if it's different metals that can have galvanic reaction with each other?

A. At the top sandwiched between strips of inertube or caulk in between 2 layers of steel with self taping screws going through. At the bottom steel, caulk or inertube, AL, roofing screw with ruber washer.



Q. What specific things (other than being able to play basketball - ha!) inside the bus do you desire that high of a lift?

A. Lofts



Q. Do you plan on a lot of driving, or mostly leave it parked from one place to

A. Mostly parked but i do want to do some travle. My guess 6 months per location.
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Old 01-22-2016, 03:34 AM   #24
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The ribs I had made. Some are full ribs so I could custom cut the corner ones and others had 8"of flange missing for the overlap.




Made a jig to drill all the plug weld holes. Cut holes 3/8"





Ribs with the holes drilled. Had to wipe off the oil befor welding. 4 holes each side 3 each face for 11 on eachend and 22 on each rib. 22 plug welds times 32 ribs........... alot of plug welds





Grinding off burrs






Due to the depth of the rib the sheet metal company could not go all the way to 90* so I used clamps with a bit of tubular steel for leverage to squeez all up and down the rib to get a tight fit. After a few I realized the flat footed one woulden't ding up the rib




Welding them in





Adding weight to the roof to drop it 1/8" to get the exact mesurment/ goofing off.



You can see the rachet straps we used to keep things square while we welded in suports







That was a floppy thing to cut. We put thes at the top and bottom of the cut/original material between the rib and the skin.




Throwing in some triangulation.




Turning the emergency exits in to standard windows. (I know every one hates bus windows)





Making some longer material for the new door jam




Fabricated my own D Tube for the 2 front corners comming off the windshield out of 1x2 and 2" pipe. Its steped so the bottom slides in and the the rest is above.





The rear corner pillers. Amazingly stout for 16Ga this was the sheet metal guys second attempt. There is the flange 1" of flat the radius 1" of flat and then the other flange. His first attempt was just flages and radius. He also told me a week after I came in some one elts in the Sedona area asked for the same thing but with deeper ribs, so if you on here say hi.





Finally framed in the front door and window stringers.
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Old 01-22-2016, 09:56 AM   #25
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Zoomy glad to see you using (what appears to be) a rust free bus. Some folks aren't so lucky and down the road I'm afraid will have issues.

Is it an AZ bus? We got ours from AAA in PHX. It served in the Peoria School System until '14 when I bought it. Absolutely zero rust, looked like it had never been on a dirt road it was so clean underneath!

Do you have a projected date of completion?
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Old 01-22-2016, 11:22 AM   #26
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Quote:
Originally Posted by 2kool4skool View Post
Zoomy glad to see you using (what appears to be) a rust free bus. Some folks aren't so lucky and down the road I'm afraid will have issues.

Is it an AZ bus? We got ours from AAA in PHX. It served in the Peoria School System until '14 when I bought it. Absolutely zero rust, looked like it had never been on a dirt road it was so clean underneath!

Do you have a projected date of completion?

I also got mine from AAA. Was trying to get it cheaper but between time crunch and being the right bus I went with them. He also gave me some extra clear windos for my green house section. Mine is from cave creek, no rust but lots of dust.

Completion date??????? LOL last month!! Raising a kid on my own and now being a full time student has slowed me down. Hoping to be moved in by the end of the semester but Rik my friend that has been helping me is getting bussy with work so if I'M on my own then it might go even longer.
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Old 01-22-2016, 11:30 AM   #27
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Question

If you ever find your self board and with out any thing to do your more than welcome to come by and give me a hand
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Old 01-23-2016, 12:08 AM   #28
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Rear corner pillers in place. You can also see how I delt with the whole backend




The rubber strip that the factory put in the seams that is reminiscent of the inertube strips that the guy at Ace recomended.




Rik trying to be a vato. Got all the new steel primed. Most of the existing steel was galvenized.





Things look so bright and shinny in side with the silver metalic primer on......and with the tarps off





Night pic




Outside after priming. You can see the homemade D tube that we made for the front corner pillers.




The infamous Aluminum skin being beaten in to shape. Used my 1,000 yard target for an anvil to keep it flat.
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Old 01-23-2016, 08:23 PM   #29
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And now we are up to date on my project.

My biggest problem that I need all of your help on is, after removing the wiring to the exit doors how do I by pass all the buzzers and lockouts?
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Old 01-23-2016, 09:52 PM   #30
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Quote:
Originally Posted by zoomy View Post
And now we are up to date on my project.

My biggest problem that I need all of your help on is, after removing the wiring to the exit doors how do I by pass all the buzzers and lockouts?
http://www.skoolie.net/forums/f10/how-to-remove-the-thomas-vandalock-ignition-interlock-10956.html
Maybe this thread will help.
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