Climb is not dependant on lift.

[gripen]

Holden McGroin,
Read Badboy's post above; basicly a sailplane is sinking all the time (relative to the air around the plane) but the air around the plane might be rising (due to thermal or some other reason) faster than the sink rate of the plane ie the plane gains altitude.

gripen

[Holden McGroin]

There are times in a sailpanes flight where it is not sinking.  It is climbing when pulling up in a loop for instance.  It expended potential energy of altitude in order to gain the kinetic energy for the pull up, and the net after the manuver is a sink, however it climbs during the pull up.

I realise it is somewhat a semantic argument, but if one defines lift as the force necesary to overcome the pull of gravity, and my back feels that when I lift the couch, then all flying vehicles climb solely dependant on lift,  whether that lift is aerodynamic lift given by forward speed and differential pressure on an airfoil or the chemical thrust of Jupiter engines on a Saturn V.

[bunch]

More importantly, what about induced drag in ground effect?

[gripen]

Holden McGroin,
Well, making a loop with a sailplane is not a steady climbing condition as discussed in this thread.

The lift discussed in this thread means lift generated by the airframe (wing etc.).

gripen

[bunch]

I'd bet Mr. Harris could add on a mile or two more, given just the right unstable tropical airmass

[Badboy]

Originally posted by Holden McGroin
There are times in a sailpanes flight where it is not sinking.  It is climbing when pulling up in a loop for instance.  It expended potential energy of altitude in order to gain the kinetic energy for the pull up, and the net after the manuver is a sink, however it climbs during the pull up.

There is an important distinction to be made though, when you pull the nose up above the aircraft's maximum climb angle, it is referred to as a zoom climb. That's when you gain altitude at the expense of speed, it is not sustainable, and there is a net loss in energy in contrast to a steady state climb in which energy is being gained.

Hope that helps...

Badboy

[Badboy]

Originally posted by Angus
Or am I lost here?

Yep, but keep reading and asking the right questions, HiTech HoHun and Gripen are posting good information.

Badboy

[Angus]

Aha.
From Gripen:
"Angus,
The required lift (of the wing) in the steady climb depends on the weight of the plane and the angle of the climb. Decreasing the wing area means just that same lift must be produced with less area (assuming that the weight of the plane stays constant). "
So, to produce enough lift to keep that smaller winged aircraft airborne with the same given power, you need a higher A.o.A., which gives you a higher induced drag, while the parasite drag from a smaller wing is less, right.
So it should also work the other way, increase the span or area a little, you have a lower wingloading and can therefor fly at lower A.o.A. with therefor less induced drag, but more parasite drag.
So, am I then wrong to say that by altering the wing you DO affect the lift outcome at the same power at a given speed?

[hitech]

So, am I then wrong to say that by altering the wing you DO affect the lift outcome at the same power at a given speed?

Yes you are wrong,if you are refering to steady state flight.
(i.e. level or steady state climb)

The lift will not be change at all. The AOA required to generate the lift will change. Also the max. amout of lift availible at any given speed will also change.  And the amount of drag will also change hence changing climb rate. But the key point is, it is the drag that is changing the climb rate, not the lift.

But now life gets a little more complicated decreasing wing area will typicly reduce drag at higher speeds and increase it at slower speeds. So now at slower speeds the plane will climb worse, and at higher speeds the plane will climb better. But the total amout of lift for steady state flight at any speeds will not have changed at all.


HiTech

[Angus]

Aha!
"Also the max. amout of lift availible at any given speed will also change."
It's me putting the wrong words up I guess, this is actually what I was trying to promote. Availability of lift it is.
So...
Thanks

[Holden McGroin]

Originally posted by Badboy
There is an important distinction to be made though, when you pull the nose up above the aircraft's maximum climb angle, it is referred to as a zoom climb. That's when you gain altitude at the expense of speed, it is not sustainable, and there is a net loss in energy in contrast to a steady state climb in which energy is being gained.

Hope that helps...

Badboy

Slight edit... when you gain altitude at the expense of fuel, it is not sustainable, and there is a net loss in energy in contrast to a steady state climb in which energy is being gained.

Same same...

Kinetic energy from potential or from chemical causes lift.  Lift allows climb.

It's just how you look at it, I look at it from a lift POV.

[Angus]

Well, imagine completely still air. You haul a glider up high and release it. It just depends on wings and weigh how far it will go right?

[Badboy]

Originally posted by Holden McGroin
Slight edit... when you gain altitude at the expense of fuel, it is not sustainable, and there is a net loss in energy in contrast to a steady state climb in which energy is being gained.

A zoom climb can only be sustained for a very short time and a relatively small altitude increase before the speed bleeds off. However, a steady state climb can be sustained until the aircraft reaches its ceiling, and that can be repeated until the fuel runs out... That's as sustainable as it gets in aviation.

Badboy

[Holden McGroin]

Okay, I understand completely the forces required to fly.  Not a problem...

Like I say this is largely a semantic argument, but to say that lift is not a factor in climb is erroneous.

An airplane that has no lift does not fly.  Without flight, an airplane will not climb.

Therefore climb is dependant on lift, as opposed to the title of this thread.

And Badboy, the only difference is the amont of energy you have in reserve for climbing.

[Angus]

Getting to the thread headline, "Climb is not dependant on lift", one can play the words a wee bit.
This refers to WW2. Now, no WW2 aircraft flown by a pilot could climb without  lift, if you see what I mean
Cut them wings off and the kite won't fly.

But HiTech got my head spinning a bit, but it was all about the availabiliy of lift. So, I must say thanks again for clearing up some definitions HiTech , but basically I wasn't that lost at all in the base theory.

(I think )