Wing Loading / climb rate

My curiosity has been about the effect of just gross weight vs. wing loading on the

For example, let's stipulate a thermal providing a vertical force ( I avoid using newtons as the SI unit for force. I've never managed to get comfortable with it.) that would provide +5 kt lift to a glider with a gross weight of 800 lbs and a wing loading of 10 lbs / sqft.. I'm just making this stuff up. I am not trying to be realistic!

Now let's invent another glider with a wing loading of just 5 lbs / sqft. but with the same gross weight as the first glider.

Would the second glider, with a wing loading of just 5 lbs / sqft, get a better climb rate than the first glider since it appears it would need only half the lifting force per square foot of wing than would the first glider?

On Friday, February 3, 2017 at 10:19:00 AM UTC-7, Jim wrote:
My curiosity has been about the effect of just gross weight vs. wing loading on the

For example, let's stipulate a thermal providing a vertical force ( I avoid using newtons as the SI unit for force. I've never managed to get comfortable with it.) that would provide +5 kt lift to a glider with a gross weight of 800 lbs and a wing loading of 10 lbs / sqft.. I'm just making this stuff up. I am not trying to be realistic!

Now let's invent another glider with a wing loading of just 5 lbs / sqft. but with the same gross weight as the first glider.

Would the second glider, with a wing loading of just 5 lbs / sqft, get a better climb rate than the first glider since it appears it would need only half the lifting force per square foot of wing than would the first glider?

Unfortunately it is not that easy. The short answer is the lighter wing loading glider will climb better, just as the heavier will run better. The long answer is they won't fly at the same speed so the lighter wing loading glider has the advantage additionally of working a tighter core.

Thank you Tim. I am beginning to understand it all.

JIm

On Friday, February 3, 2017 at 1:26:02 PM UTC-5, Jim wrote:
Thank you Tim. I am beginning to understand it all.

JIm

Those of us who flew hang gliders/paragliders already understand this relation between weight, area and efficency. Hang gliders have a lower sink rate and better glide than paragliders but the much larger area of PG allows them to slow down and turn very tight circles in lift so they can outclimb HG much of the time.

Yes, I have enjoyed slower-flying thermal-working too. It's lots of fun.

My curiosity about wing loading and climb rate really is limited to non-thermalling, non-turning flight. I was wondering about the possible relationship of wing loading to lifting force. Likely an unrealistic circumstance in actual flying though. Just a curiosity.

Le lundi 13 février 2017 04:52:04 UTC+1, Jim a écritÂ*:
Yes, I have enjoyed slower-flying thermal-working too. It's lots of fun.

My curiosity about wing loading and climb rate really is limited to non-thermalling, non-turning flight. I was wondering about the possible relationship of wing loading to lifting force. Likely an unrealistic circumstance in actual flying though. Just a curiosity.

Well, on a good soaring day, about 70-80% of the flight is non-thermalling, non-turning flight.
And the lifting force always matches the weight of the glider, regardless of wing loading.

Well, on a good soaring day, about 70-80% of the flight is non-thermalling, non-turning flight.
And the lifting force always matches the weight of the glider, regardless of wing loading.

Yes. I understand that. If the glider is not to accelerate downward the total "lifting force" equals the current gross weight (and drag vector too I guess) of the glider. My silly curiosity has been about exactly the point you make. Everything else being equal ( I know, never happens), does a wing that supports 10 lbs per square foot of wing area require the same TOTAL"lifting force" as a wing that supports 5 lbs per square foot of wing area - but has twice the wing area? IF this is the case it would suggest that the glider with half the wing loading but twice the wing area could be sustained by a smaller "lifting force".

This is just a curiosity. I don't think this has ever entered into my decision making during flight. Not that I understand that either.

If the lifting force exactly matched the weight of the glider then, in
still air, wouldn't the glider not lose altitude? Or are you saying
that the sink rate of the glider is cause by drag?

On 2/13/2017 6:46 AM, Tango Whisky wrote:
Le lundi 13 février 2017 04:52:04 UTC+1, Jim a écrit :
Yes, I have enjoyed slower-flying thermal-working too. It's lots of fun.

My curiosity about wing loading and climb rate really is limited to non-thermalling, non-turning flight. I was wondering about the possible relationship of wing loading to lifting force. Likely an unrealistic circumstance in actual flying though. Just a curiosity.
Well, on a good soaring day, about 70-80% of the flight is non-thermalling, non-turning flight.
And the lifting force always matches the weight of the glider, regardless of wing loading.

--
Dan, 5J