Negative pressure in the back? How much?
Jerry
Posted 2010-03-06 11:30 AM (#1000)
Subject: Negative pressure in the back? How much?



Regular

2525
Location: Clovis, Ca
Everyone has always told me that the back of the coach is a negative pressure area. Conceptually, I understand that.

The coach is basically a huge block moving through air, meaning there is a high pressure pushing on the coach in the front (and slightly on the sides and roof), and a low pressure area "sucking" the coach back in the rear.

BUT HOW MUCH???

If ambient is 14.7 PSI, is the low pressure area in the rear of the coach a couple of PSI less? Five PSI less? What is realistic in this?
I am asking because we are once again looking at the cooling question with fresh eyes. What is realistic?
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Barney and Connie
Posted 2010-03-06 4:15 PM (#1001 - in reply to #1000)
Subject: RE: Negative pressure in the back? How much?


Veteran

100
Location: Kingsley Michigan
Jerry---
You are asking a question that can only be answered with scientific test results--as I too have wondered amny a day and night about why this coach is so hard to cool while a greyhound whizzes by with a bigger front end and load but with no cooling problems--sooo
I am building a Manometer with a sensative scale to test the actual and try to find the problem areas---

Over the years --I found that the biggest problem was old technology---and an enormous and inefficient brass radiator--which can easily be replaced with an inexpensive single or 2 core aluminum one with fantastic results---almost like a real car or bus---

But you are on the right track and I will be trying to help you find some of the answers to a better airflow--and maybe eliminate the botched waterpump/fan issues in the back as well--

Barn
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Jerry
Posted 2010-03-07 12:02 AM (#1003 - in reply to #1000)
Subject: Re: Negative pressure in the back? How much?



Regular

2525
Location: Clovis, Ca
I think the bigger buses direct the side air to the rear facing radiators. In other words, they are drawing ambient air to the radiator, not engine bay, preheated air.

I am VERY curious to the results you come up with on your manometer test. Please do post!
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wheelsweep
Posted 2010-03-07 10:11 AM (#1005 - in reply to #1003)
Subject: Re: a Flxible approach


Contributor


My original "pusher passion" was the flxible clipper w/skyhook!! Roof radiator ram...

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Jerry
Posted 2010-03-08 1:28 AM (#1009 - in reply to #1005)
Subject: Re: a Flxible approach



Regular

2525
Location: Clovis, Ca
They really had a good idea with the clipper. No cooling issues there!



(Flxible Clipper cooling diagram.jpg)



Attachments
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Attachments Flxible Clipper cooling diagram.jpg (34KB - 30 downloads)
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Jerry
Posted 2010-03-08 1:32 AM (#1010 - in reply to #1000)
Subject: Re: Negative pressure in the back? How much?



Regular

2525
Location: Clovis, Ca
We are now leaning toward mounting a conventional aluminum radiator flat against the rear of the coach. We are thinking about pulling ambient air in just ahead of that (on the side) with a large electric fan.

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