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Steven Boese wrote:
Ernest,
I apologize in advance if you have taken the following into
consideration already:
The units of manifold pressure that are usually used are inches of
mercury. To convert inches of water to inches of mercury, divide by
13.6. That means that the highest pressure that was generated was less
than 2 inches of mercury over atmospheric pressure of about 30 inches.
I'm not sure this is the amount of boost you were hoping for.
Steve Boese
Not what I'm hoping for in the final product. It was more just to see what a centrifugal blower will produce. Some people on this list know a lot about them, and have worked with them a lot. I'm not one of those. I found out a 5" fan can give 2" of mercury. I ?believe? that is significant. I could be wrong, but that would give a measurable increase in Hp, even after taking into account the power lost to producing it.
The next step in this particular sub-plot will be to get my bellhousing finished, get a fan and build a shroud. I can attach it to the gearbox and drive it with my drill press from the propeller drive. Running the 3.17 reduction in reverse, I should be able to get 6000RPM on the fan side. Then I can run through this same set of experiments. Adding in an airspeed measurement and knowing the exit tube size(s) will give me an idea of the airflow. Graph the results, pick out the head pressure at 277CFM and I'll have a reasonable chance of making a good SWAG at how much power I can expect to pick up. The only piece I'd like to add in is a power meter on the drill press so that I could more accurately determine how much power I'm putting into it.
I'd expect the whole thing to take no more than a couple days. One to rig up a shroud, and a couple hours the next to take measurements. All the parts involved that require careful construction would have to go on the airplane anyway, so there isn't going to be much time lost.
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