Tom,
As always, I consider all options.
Your advice on circuit protection is certainly good practice, although I also
advise including a power relay, to prevent switching high current
in the cockpit. Current design practice does not even use an ammeter.
I have found that, aside from my structural evaluation of the radiators
stiffness ( you could support a car on toothpicks, so it's not the
strength of the elements, but the structure), and the fans I was evaluating are
very light. But, your argument about chafing thin elements
with the "tie-wraps" has a good deal of merit, and I will incorporate that
advice in my installation.
Gap sealing was not an issue with the tie-wrap design, but a "fixed mount" has a
few design challenges. Inherently, a tie wrap design puts
the shroud against the radiator, and it moves with it to keep the seal. A
remote mount requires careful measurements and even adjustment
capabilities to control location. Not only should you be close to the radiator,
but should not touch it, even during shock and vibration. So a
gap is required. Due to potential mount flexibility, and independent motion, a
movable seal is desirable, but chafing is not. A split rubber
3/8 hose was recommended as a sealer, as well as foam tape. Each has it's
points.
Blade design is a matter of compromise. Well, at least blade availability is.
The curved blades typically have a connecting ring around the
blade tips. This allows additional stiffness of the assembly, and a lighter
design with less tip loss and greater efficiency. The curved blades
are quieter, but less efficient. Unfortunately, flat blades and tip ring
shrouds do not appear to be offered. This would give the best design.
Motor consideration is also complex. The regular long motor is more powerful,
but inherently heavier and longer. This adds to the mass
needing support, the thickness of the supporting fan structure, and limitations
on the size (diameter) of the fan that will fit our space.
Nothing for nothing.
Bob Palmer has suggested a supplier here in Valencia, CA that specializes in
fans with lots of options. I chose a 13" model with straight
blades and a 3 3/4 inch "Terminator" motor. This fan has an outer lip
thickness of 1 1/4 inches and an overall thickness (including motor) of
3 3/4 inches. The thirteen inch fan model is 13 3/4 x 12 3/4 width/height. It
flows 1600 CFM at 10 amps, vs. 1200 CFM at 11 amps of the
Hayden. The blades are fiberglass impregnated polypropylene, and he supplied a
pretty complete set-up including relay, fuse, switch and
some mounting ears. The cost is higher, and the 13 inch model is about the
same dimensions as the 14" Hayden.
Bob reports good performance. I will advise my experience, once I have any.
For those interested, contact:
Gary Wilson
Scotts Manufacturing Co.
25520 Ave. Stanford, STE 304
Valencia, CA 91355
805-295-9340
800-544-5596
FAX 805-295-9342
Thanks for the input Tom and Bob.
Steve
--
Steve Laifman < One first kiss, >
B9472289 < one first love, and >
< one first win, is all >
< you get in this life. >
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