Dear rp-ml:
We are wanting to run some water tunnel tests (two-by-three-foot test
section with flow velocities going up to 1 fps) utilizing stereolithography
models (SL5195 resin) to collect some preliminary data on some control
surface shapes. The models will be completely immersed in the water tunnel
for several 8-10 hour long test periods.
Anybody out there find any good waterproofing agents for SL models?
I've heard that acrylic lacquer and Imron (polyurethane) paints are very
good coatings (Thanks for the info, Jeff and Steve from Boeing and Ed from
Lockheed). We're also looking at a ceramic sprayed-on coating.
Anybody tried Thompson's Water Seal or a similiar type waterproofing
coating?
If so, did it affect the model's accuracy, any swelling,
softening/deflection problems, etc.
Porsche used waterflow testing on a cylinder head, anybody out there
familiar with these tests and did they just use an untreated SL model? Did
they have any problems with surface swelling or accuracy problems?
There will also be pressure ports going throughout the model - we're
thinking of trying several options:
a) just using the SL ports with no inserts but since the hole diameter has
to be .025" we're concerned about the accuracy and our ability to
adequately clean out the holes of excess resin and will the holes constrict
because of swelling if we can't adequately seal the resin,
and
b) model the holes oversize and bonding in either stainless steel or
plastic tubing inserts but then we're concerned about any leakage around
the outside of these inserts.
Different colored dyes such as red, blue, and yellow will be introduced
into the water flow for better visualization - we don't want this dye to
absorb into the model either so whatever seals out the water needs to also
seal out the dye from permanently staining the model. A white coating is
the most preferable coating color to provide a good contrast between the
model and the dye flow.
Any additional helpful ideas or information sources out there?
Thanks in advance.
Glenn Whiteside
Cessna Aircraft
e-mail: siderwhite@worldnet.att.net
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