Do winglets produce thrust?

Nope not at all! ( Sorry Bernhard ) and that's why I cut out his posting

I just wanted to add to the tail of the 'discussion.'

Ian


"Eric Greenwell" wrote in message
...
tango4 wrote:

I'm amazed at the complete lack of understanding of the basic principles
of
physics displayed by some posters in this thread. No wonder people can
still
sell constant motion engines to investors!

Surely you don't mean Bernhard (my newsreader shows you replying to his
post)? His diagrams look correct.

--
-----
Replace "SPAM" with "charter" to email me directly

Eric Greenwell
Washington State
USA

Bernhard's diagrams are spot on, but whether you call
it thrust or a reduction in drag is up to you. My Aeronautical
Engineering textbook uses both as alternative ways
of describing it. It all depends on how you choose
your frame of reference. The winglet produces a vorce
vector which consists of drag and lift, but when this
force vector is considered with the sailplane as the
frame of reference then its components could be considered
as a thrust force and a lateral force. I feel that
this is the easier way to describe the way they reduce
overall drag, but if you want to be pedantic........

Jon Meyer wrote in message ...
Bernhard's diagrams are spot on, but whether you call
it thrust or a reduction in drag is up to you. My Aeronautical
Engineering textbook uses both as alternative ways
of describing it. It all depends on how you choose
your frame of reference. The winglet produces a vorce
vector which consists of drag and lift, but when this
force vector is considered with the sailplane as the
frame of reference then its components could be considered
as a thrust force and a lateral force. I feel that
this is the easier way to describe the way they reduce
overall drag, but if you want to be pedantic........

If there is only drag and no thrust you'll eventually be
flying backwards, right?

Suppose you raise your glider up into the air under a balloon and
drop it. If the wings (nor anything else) generate only lift and
no thrust then you'll just move in the verticle direction only,
or hover.

If a wing can generate thrust then so can a winglet depending on
geometry, AOA etc. It will also generate drag and weight.

--

FF

Let's go back to the beginning. The FAA likes to teach four =
balanced forces, lift exactly cancelling gravity [weight] and thrust =
exactly cancelling drag. Unstated or widely ignored assumptions are a =
powered aircraft, constant altitude, constant speed, stationary airmass. =
This does not normally apply to a glider !

Starting with your Cessna flying per FAA model, take away the =
engine's thrust. Now something has to give - you can fly slower at =
constant altitude as drag exerts a decelerating force on you; lift would =
be reduced as airspeed drops, so to maintain altitude you increase angle =
of attack [until you stall, then you will descend]. Or you can choose =
to hold airspeed and descend by nosing down a little; then both the lift =
and drag vectors are tilted relative to gravity, and two things happen - =
a component of your total lift will resolve in the 'forward' direction =
90 degrees from the gravity 'down' direction AND a component of your =
total drag will resolve in the 'up' direction. Only three primary =
forces [lift, drag weight], resolved and summed in four directions. You =
stabilize at a new flightpath angle, same speed, same angle of attack =
[because your nose down input changed both fuselage angle and flight =
path angle by equal amounts after transients wash out] and therefore =
same drag, constant descent rate. That's how a glider works, I believe. =
The vectors can be drawn EITHER in space coordinates [true up and down] =
OR flightpath coordinates but please don't mix 'em together.

Note that of your three primary forces, weight is always there but =
lift and drag only exist because you have airspeed to begin with. And =
you need altitude as well, otherwise you can't fly down your slope.

To get to this stabilized state in the first place, you must have =
airspeed and altitude. Bungees, winches, towplanes, ramps off clifftops =
all supply the initial energy to get this altitude/airspeed to start you =
off.

Now soaring, that's a different matter, and really starts when the =
airmass motion comes into play..

Ian