Pullups, I stand corrected!

Lars,

I think you may be forgetting something else. For the same speed of travel,
the light glider is using energy faster than the heavy glider. It seems
paradoxical, but it is true - look at the loaded and unloaded polars to see
that the heavy glider is either: a) travelling faster for the same sink
rate, or b) sinking less for the same speed of travel (provided that the
speed of travel in both instances is above the crossover point for the
polars, the speed this occurs at depends on the wing loading).

So, as they zoom upwards during the pull up: a) the light glider is using up
its energy faster than the heavy glider, and it has less to start with, and
b) the heavy glider is using up its energy slower, and it has more to start
with.

The heavy glider, of the same type, goes higher.

Rgds,

Derrick.

My god!!!!
The polar for a given glider is reprentative of gliding flight
characteristics. Once your nose is pointing up, you are coasting, you are
not gliding anymore....so forget about the polar......and at the risk of
becoming rude let me add this.........LIFT IS NOT HELPING YOU ANYMORE it may
actually pull you away from optimal trajectory. Being the one who started
this whole discussion, I am starting to think that I missed a good occasion
to shut the F...up! But what the hell!!!! it all started in front of the
club house, we're all drinking beer, and I throw The QUESTION!!!!! Immediate
answer from everybody the ballasted is actually going wayyyyy
higher!!!!!!!! I said that I doubt it, and did a littlle maths (you don,t
have to own an eng. degree......which I do ), checked the drag, the only
force that could make a difference and came to conclusion the the light
glider has an edge, contrary to popular belief. So I came back to my
buddies, thinking I was bearing the Good News. I was looked down at ( I am
joking ok!!) So short of doing a real test, which is not easy to do
"scientifically" I though of posting a message on this forum
here!!!!!!!!hell broke loose (I am joking again) but yet I am amazed to see
that the "Non-silent" majority is pro-ballasted. One can easily realise how
your intuition can mislead you on this ......but yet we have some
experimented pilots who are doing the maths to prove their intuition, and
they do it in a much scientific way. So I can't wait to see the new sets of
equations, and the coasting polar (this is not a joke). we are actally
having fun,no? Me I have no proof to offer, and I feel a little obligated,
being the one who set the fire. So we are desperatly begging anyone who
actually did some testing to come forward and put an end this nightmare
;-), before we start throwing punches at each other!!!!We have alrerady
witnessed people using capital letters in their message!!!!!
Again, as someone mentionned earlier, please stop throwing ping-pong and
golf balls at us. The Cx of a sphere is .42, which makes it the worst
aerodynamic shape, an it quickly build a force that will oppose accelaration
at a low speed, which is not the case of our beautiful gliders, at he
operating speed, ther is not much difference in form (parasite drag),
neighter for induced drag for which the heavy will suffer more during the
pull-up
The debate is not over yet!!!!We need a proof!!
BQ

"Derrick Steed" a écrit dans le
message de ...
Lars,

I think you may be forgetting something else. For the same speed of
travel,
the light glider is using energy faster than the heavy glider. It seems
paradoxical, but it is true - look at the loaded and unloaded polars to
see
that the heavy glider is either: a) travelling faster for the same sink
rate, or b) sinking less for the same speed of travel (provided that the
speed of travel in both instances is above the crossover point for the
polars, the speed this occurs at depends on the wing loading).

So, as they zoom upwards during the pull up: a) the light glider is using
up
its energy faster than the heavy glider, and it has less to start with,
and
b) the heavy glider is using up its energy slower, and it has more to
start
with.

The heavy glider, of the same type, goes higher.

Rgds,

Derrick.

For your convemience, here is two sites that explain lift and drag on
aircrafts, complete with some graph and theory and all.
http://www.av8n.com/how/htm/4forces.html and
http://www.go.ednet.ns.ca/~larry/bsc/winch/winch.html
I hope this help
BQ
"Todd Pattist" a écrit dans le message de
...
"szd41a" wrote:

checked the drag, the only
force that could make a difference and came to conclusion the the light
glider has an edge, contrary to popular belief.


I forgot, how did you arrive at this? The light glider has
the advantage of being able to slow to a lower stall, but as
far as drag goes, the heavy glider has the advantage (in
terms of altitude lost) at all times.
Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)

In article ,
Stefan wrote:

Stall speed isn't the limit. If you go ballistic at the top, i.e. if you
push to zero G, then you can slow down to zero km/h if you wish (or to
zero knots, if you live in the USA).

Sure, but that doesn't help you fly your circuit.

-- Bruce