-----Original Message-----
From: Raymond Wong [mailto:[EMAIL PROTECTED]]
Sent: Monday, December 06, 1999 7:47 AM
To: [EMAIL PROTECTED]
Subject: [RCSE] hi wind = zero lift?
It was very windy today, on sea level it was 15m/s(someone please tell
me how to convert to knot?)
when I got up to the top of the slope the wind felt like 70kph head on.
The slope is usually very efficient even in light wind. I said to
myself the more wind the more lift the more fun. I took out a foamie,
and try to launch it. it was difficult just to hold it stable against
the strong wind. finally i let it go. i was really expecting it to
shoot right up, but it did not. it went up at most 20ft and just stay
there, not moving forward or backward, just sinking slowly. when i push
the nose down it lose 10ft height and only move 2ft forward. if i pull
the elevator it will gain only 5ft, then stop and come back down 10ft. I
did that for the whole hour before i finally gave up.
lift was good on a light wind day. zero lift on windy day.
can anyone explain to me what happened?
Raymond Wong
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
Your model was not penetrating. Ballast probably would have helped. A model
designed for higher winds would have faired much better. If you are at a
flyable slope, and the wind is blowing into the face of the slope, lift WILL
increase as winds increase. However, many slopes will have a lot of gusty
hard to penetrate air right on the edge. Once you get up and away from the
hill and into the smooth lift band flying becomes much easier. When a good
wind is blowing the best lift will be a lot higher up and a lot further away
from the hill than it will be on a lighter day.
A good example of the conditions you described have been happening here on
Maui recently. The trade winds have been blowing at 25-35 miles per hour for
the last week. ( A few of us flew at our monster cliff face yesterday with
winds measured at a constant 40 MPH plus with much stronger gusts
occasionally, you could have sloped a manhole cover if it had ailerons and
strong enough servos... but that's another story.) The favorite local slope
is inland and above the coast it faces, and the winds there are not as
strong as down on the coast. Still the winds there have been blowing a good
15-25 mph. The high performance scale aerobatic sailplanes and fast sport
slope planes have been ripping it up. Many of the guys with foamies and
light lift slopers were wallowing around in the gusty launch conditions,
constantly losing altitude and crashing into the bushes down-slope as the
big boys played above. If a foamie did manage to penetrate the lip and get
up into the smooth lift band and finally get some speed happening, it would
then do alright. Once you get up there it is easy to dive down gaining speed
and energy enough to buzz the slope face and still have the velocity
required to smoothly climb up into the lift band again.
If you try to fly your foamie at that spot on another really windy day, tape
on a lot of lead, probably 8-12 ounces worth or even more, and on launch
concentrate on keeping the wings level and try to push trough the wind until
you get into the lift band. Believe it or not you will need to use a lot of
down pressure on the stick. Essentially your model thinks it is in a shallow
dive which it needs to be able to maintain airspeed, in reality the model
will still be climbing in the strong lift. When you reach the best lift band
(and you might be shocked how high and far away it will be) the plane will
become way easier to fly, and you will begin to have huge fun taking
advantage of the nearly limitless flying energy that strong slope lift
provides. Good luck!!
RCSE-List facilities provided by Model Airplane News. Send "subscribe" and
"unsubscribe" requests to [EMAIL PROTECTED]
