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Old 09-05-2014, 10:10 PM   #121
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Re: The Broccoli Bus

The rear engine on this thing looks like zero consideration was made for ram air cooling. The radiator is sideways and simply sucks in from the outside of the bus. It's hydraulically driven at least, so when the fan motor explodes your power steering will probably go too.

Quote:
Originally Posted by jazty
Fun fact for some (all?) of you who own a front-engine bus on an International chassis and possibly others:
Have you noticed where the air intake is on the hood/cowling? It's right below the front windshield with the opening facing the windshield. Why? Because the windshield creates a high pressure area which helps push air into the engine! Or so I've read, anyhow.
Now that's clever use of poor aerodynamics...
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Old 09-06-2014, 09:59 AM   #122
Skoolie
 
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Re: The Broccoli Bus

Jazty,
.....the Broccoli Bus is a RE-bus.

By the time air hits the rear of the bus it doesn't matter what you do to the front end....
[...unless something happened since the pics on page 1 ]

thjakits
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Old 09-06-2014, 10:58 PM   #123
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Re: The Broccoli Bus

Here is a photo of the team working on the bus, from right to left.

Chris, Cory, me, Nick, and Ava.

Cory is my riveting expert, Nick and Chris work at my shop rebuilding unimogs. They are good at everything.

Ava is my oldest daughter and she cleans up and brings us cold drinks.

Sam is the dog. He just wants to be loved a lot.
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Old 09-07-2014, 05:06 PM   #124
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Re: The Broccoli Bus

Man!

YOU ARE SET!!

thjakits
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Old 09-07-2014, 09:05 PM   #125
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Re: The Broccoli Bus

Quote:
Originally Posted by thjakits
Jazty,
.....the Broccoli Bus is a RE-bus.

By the time air hits the rear of the bus it doesn't matter what you do to the front end....
[...unless something happened since the pics on page 1 ]

thjakits
Yes, I was and am very aware of that. With the talk of air-dams and the effect of aerodynamics on the air passing through the radiator I just thought it might be an interesting tidbit of info.
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Old 09-07-2014, 10:14 PM   #126
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Re: The Broccoli Bus

Getting a lot of the rivets complete.

All the hard parts are done, now its just a lot of the straight spars which go fast.

I'd estimate about 60 percent of the rivets are placed.
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Old 09-07-2014, 10:21 PM   #127
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Re: The Broccoli Bus

The re bus really has about the same aerodynamics as a standby generator bolted to a pad I think.

Photo of the side access to the radiator and the way its mounted in the engine bay.

Bottom of the bay is just open.





Quote:
Originally Posted by jazty
Quote:
Originally Posted by thjakits
Jazty,
.....the Broccoli Bus is a RE-bus.

By the time air hits the rear of the bus it doesn't matter what you do to the front end....
[...unless something happened since the pics on page 1 ]

thjakits
Yes, I was and am very aware of that. With the talk of air-dams and the effect of aerodynamics on the air passing through the radiator I just thought it might be an interesting tidbit of info.
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Old 09-08-2014, 12:33 AM   #128
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Re: The Broccoli Bus

I've always wondered if a scoop or something would push more air in through those. I am sure the engineers made the appropriate compromises in function and what-not, but I just don't see how that is the most efficient and effective method for cooling a rear-engine. Maybe some graduated louvers would be better than a single scoop. That would leave the full screen open but provide some ram air on movement... What do y'all think? Maybe someone can grab a set off an old Saab or Camaro or something from a boneyard and run some tests? You know the ones that look like this:

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Old 09-08-2014, 02:54 PM   #129
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Re: The Broccoli Bus

Jazty, ...sorry! I was readying way to fast and missed the details in your original post!!

You won't believe it, but many manufacturers lack some serious aerodynamic knowledge and/or just approach things with a "a bigger fan will solve that" attitude.
Aerodynamic R&D often is not done in house but contracted out...

There are two old books out there (from and before WW2, FLUID DYNAMIC LIFT and FLUID DYNAMIC DRAG by Hoerner)
[In case you wonder - a lot of performance was to be gained by streamlining the huge cooling needs of the aircraft engines - what applies to them applies to road vehicles just the same, at somewhat lower performance scale]

There is a LOT of formulas and drawings in there - ...just looking at the drawings and analyzing the comparisons you could solve a LOT of the cooling problems and even improve on efficiency!

Have a closer look: Most fan arrangements do NOT seal to the front of the radiator - a big deal of forced airflow escapes to the sides before going through the radiator.
A lot of time, there is not enough space behind the radiator for the air to escape freely!

I bet instead of huge louvers are small line of vortex-trips in front of the intake and possibly a small lip at the rear could change the pressure in front of the radiator dramatically....

thjakits

AS mentioned the floor is open in the engine room, maybe even to the rear, but what about UP??

Hot air loves to rise!! WHY force it any other way??

You don't want huge louvers on the side - you will not always drive at full speed - what about trundling along a mountain road or in traffic and having a strong tailwind - effective ram-air could become ZERO in a heartbeat.

Some experimenting along the lines published in autospeed.com can show you fairly quickly where the different pressure areas on your bus are.
After that it would be fairly easy to start to work in the right direction......
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Old 09-08-2014, 03:06 PM   #130
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Re: The Broccoli Bus

I think that the way it's set up right now (rear engine, side mount radiator) is probably adequate, simply because the fan is driven all the time by a hydrostat motor. The size of the fan, and the size of the fan motor lead me to believe that thing can start blowing like prop driven airplane if it needs to. Since the inlet is small and the exhaust opening is large (the entire engine bay is open) it makes sense to exit the hot air out the bottom of the bus.

Some other thoughts: nearly every rear engine bus arrangement I see has the radiator with no real provision for passive at speed cooling. There's probably a reason for that - the coolant lines are huge, and multiple 2 - 3" water lines the length of the bus would put a lot of weight on there, as well as additional failure points along the mounting of the lines, and requiring a substantial increase in the size of the water pump to push the head of water up a hill and just drag from resistance of the water lines.

In conclusion, I think the drawbacks of using passive cooling with the vehicle moving through the air at speed I think are considerable when faced with the mechanical reality of moving the coolant from the front to the back of a 40' long vehicle.







Quote:
Originally Posted by thjakits
Jazty, ...sorry! I was readying way to fast and missed the details in your original post!!

You won't believe it, but many manufacturers lack some serious aerodynamic knowledge and/or just approach things with a "a bigger fan will solve that" attitude.
Aerodynamic R&D often is not done in house but contracted out...

There are two old books out there (from and before WW2, FLUID DYNAMIC LIFT and FLUID DYNAMIC DRAG by Hoerner)
[In case you wonder - a lot of performance was to be gained by streamlining the huge cooling needs of the aircraft engines - what applies to them applies to road vehicles just the same, at somewhat lower performance scale]

There is a LOT of formulas and drawings in there - ...just looking at the drawings and analyzing the comparisons you could solve a LOT of the cooling problems and even improve on efficiency!

Have a closer look: Most fan arrangements do NOT seal to the front of the radiator - a big deal of forced airflow escapes to the sides before going through the radiator.
A lot of time, there is not enough space behind the radiator for the air to escape freely!

I bet instead of huge louvers are small line of vortex-trips in front of the intake and possibly a small lip at the rear could change the pressure in front of the radiator dramatically....

thjakits

AS mentioned the floor is open in the engine room, maybe even to the rear, but what about UP??

Hot air loves to rise!! WHY force it any other way??

You don't want huge louvers on the side - you will not always drive at full speed - what about trundling along a mountain road or in traffic and having a strong tailwind - effective ram-air could become ZERO in a heartbeat.

Some experimenting along the lines published in autospeed.com can show you fairly quickly where the different pressure areas on your bus are.
After that it would be fairly easy to start to work in the right direction......
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