How effective are bug wipers

[John Ferguson]

Having read the various reports on the effect of bugs
on a gliders polar, 25% seems to be the quoted figure
for a modern aerofoil. I am wondering if anyone has
a quantative figure for the effectiveness of bug wipers.

I am asking this because I presume that bug wipers
which are retrofitted to gliders must cause some disturbance
to the airflow round or near the wing root/fuselage
junction. Unlike the latest DGs where the wiper is
parked in a recess.

I would expect the bug wiper sitting at the wing root
to also degrade the polar a little (?) Does anyone
have an opinion or even better fact about how much
l/d is lost when bug wipers are fitted.

I am wondering about fitting them to an LS7wl.

John

[Hank Nixon]

John Ferguson <REMOVE_TO_...@orange.net> wrote in message news:<b40inq$1r09fi$1...@ID-49798.news.dfncis.de>...

Reply:Several variables come into play:
1) How good is the wing root area on the glider in question? A glider
with poor wing root fillet area will not be seriously degraded by
having bug wiper parked there. It could even help, but not likely.
2 How badly is the glider affected by bugs? Most of the time, bug
wipers seem to reduce losses by about 1/2 to 2/3, but may be almost
completely innefective on a really sensitive ship. Solution to this is
an airframe transplant.
3 How many bugs do you get in your area.
4 Are you prepared for the hassle during rigging and derigging.
5 Are you prepared for one more distraction while flying?
6 How will ship fly with bug wiper trailing on 24 feet of wire.

They are commonly used in some areas of Europe where they get lotza
bugs, but not much in the US.

Hope this helps UH
> John