Here are two pictures of a very fast Tailwind built by Red Hamilton
that I have taken from the Tailwind list. I am sure they don't mind.
The first photo shows an angled intake which did not work because it
was in the boundary layer. There was NO increase in MP. The second
photo shows the improved intake which produced .4"Hg more MP. In the
second example, the prop clears the intake by only 1/2 inch.
I was surprised that the boundary layer formed so fast in the buffeting
air coming off of the prop. It is something we need to keep in mind
when building the belly inlet for our rads and oil coolers.
Jerry
Tremendous (deep) well of inf. here. Kudos to Paul and all of the
contributors.
FYI: I'm building a Zenith CH 801 Stol a/c. The 20B is my choice of power
plant.
Originally, I was looking at the conventional 260 HP, 6 cyl. Lycoming, then
the inline, inverted 250 HP, 6 cyl. Walter Lom, then the 255 HP Inodyn
turbine... but alas, having discovered the rotary engine's power to weight
ratio, and it's near indestructible design, my heart's a flutter for a
zoom-zoom.
I am going to stretch the wings a bit on the 801, (18"-36" per side) and
stretch the horizontal stabilizer proportional to the wings. The factory
specs. give a useful load limitation of 1,050lbs. I plan to take that up a
notch or two. Also the HP range is 150 HP - 240 HP. Again, I want to be
around 300 HP (turbocharged.) By design, firewall forward, the weight
limitation is 440lbs. If weight becomes a problem, a wood or composite prop
should help, and I definitely will obtain aluminum housings for the rotary
engine.
I'll be based in AZ, once I move from IL, and I will be operating from
airfields in the 7,000' to 8,000' msl range, so tooling around the sky at
2,000' agl, will occur at 10,000 msl. I will reinforce the airframe at key
points to accommodate the added stress of increased weight and horsepower.
Basically, I will have a poor man's C182 / C185.
Jerry,
The words 'boundary layer' jumped out at me in your message. Zenith mounts
the flaperons behind and under the wings enough to be 100% effective, unlike
traditional flaps. I know that my post doesn't address your question,
regarding the intake vs propwash question, in the body of your message.
Zenith borrowed from the Junkers design (I think) to solve the boundary
layer issue regarding the flaperons. Maybe, there's an old bird design with
an answer for you...
Thanks again for the incredible contributions from all of the builders in
the field!!!
Perry,
Lincoln, IL, USA.
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