Paul,
            Thanks for the cooling book which gives so many practical ways to
cure my problem.  The wedge, does it taper to be flush with the rear of the Rad,
or should it be up say a half inch?  I assume that the inlet is to be the
magical 1/3 of the area of the Rad ?  I expect that my actual inlet will only be
about a foot before the rad, so is it better to go wider with the inlet rather
than higher?
     THe curve before the outlet on the firewall, I have heard of this many
times, but have never been able to get a drawing.  Have you dimentions etc
available ??
     Thanks for a great book.  Met Fred Moreno at an Saaa meeting only a month
or two ago.  His Lancair is flying at last but with a Lyc!!.   What happened? He
now lives south of Perth which you probably know.
     Neil.

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I think that may be a different Fred Moreno. Did he say he was on our news
letter? If I had known he was there I would have tried looking him up when I was
in Perth early this year.

The end of the wedge must be right down on the core. In fact Ian out in Perth
claims it is well worth doing the S curve trick. Second attachment Fig 4. He has
reduced the size of his scoop drastically on his second RV6 and it is not cool
in Perth during the summer time :)

http://www.youtube.com/watch?v=uZ4NqGv6SwQ

To answer the question on the size and shape of the scoop I need to know how
fast your airplane flies. Slower airplanes can use larger openings to cool at
lower climb out speeds. Also the use of a cowl flap is a factor. A nice cowl
flap will allow a smaller scoop. I assume you have an RVx something or other.

BTW folks don't be taken in by the supposed need  for a smaller pulley on the
e-shaft to cut down the water pump speed. That may be true on a racing engine
that is going 11,000 RPM but we never see more than 7500 with a 2.85:1 gear box
and 6500 with a 2.17:1 gear box.

Also there is a remote possibility that taxi cooling can be helped by more water
flow. Some body needs to do a little data taking on that subject one way or the
other.

Paul Lamar
*********************************************

Paul,
 I received the book and found it very useful.  I do have a follow-on question similar to Neil's.  It's about Figure 4 and 5.  Why does the plenum not extend all the way back to the end of the heat exchanger?  Heck, if the fins don't run with the airflow, then about 1/4th of the radiator would appear to be effectively blocked from all incoming air in Fig 4.

Mark W.

I am not sure I understand what you are driving at here. Perhaps you are forgetting the end tanks. Fig 4 is also not the most accurate dwg. The sheet metal duct wall should extend to the end of the core. I think Fig. 4 came right out of Kays & London. Fig. 5 is a better dwg in that regard.

The orientation of the fins to the airflow probably has some effect. This has been studied and it has be found that forcing the air to trip over the edge of the fins is beneficial in terms of generating turbulence in the rest of the core. This appears to enhance the heat transfer to the air from the metal fins. That is the reason you see tiny louvers pressed into the thin sheet metal fins. If it trips over the rounded tubes the heat transfer may not be quite as high. I don't have any hard data on that yet.
                   

For those that don't already have the How to Cool Your Wankel book the $20 cash Christmas special is in effect till the first of the year.    Plus $5 cash for postage and handling.

Paul Lamar