Debunking Glider Spoiler Turns Causing Spin Thinking

On Wed, 10 Jun 2015 11:58:39 -0700 (PDT),
wrote:

Including the table of G-loading for various bank angles and L/D ratios.

G-load has absolutely nothing to do with L/D or with airmass movement.


Andreas

On Wed, 10 Jun 2015 12:13:08 -0700 (PDT), Tango Whisky
wrote:

G-load has absolutely nothing to do with L/D or (stationary) speed of airmass.


Oops Bert.... sorry for copying your posting. Didn't see yours until
now.


CU
Andreas

On Wednesday, June 10, 2015 at 11:58:41 AM UTC-7, wrote:
On Wednesday, June 10, 2015 at 12:06:04 PM UTC-5, Jim Lewis wrote:
Mostly very helpful but isn't atan(D/L) the glide angle rather than the glide ratio? Maybe once again it's largely a matter of vocabulary. I certainly don't know. Thankfully, being fairly dumb about these things has not seemed to diminish my flying skills - wishful thinking?

It's all good. I still say my answer to Dan Marotta's question
"How come nobody ever states that these G loading increases are for level flight? Since the glider is always descending, wouldn't it be better to include something about the descent rate being maintained? What about a climbing turn? Maybe some trig including the flight path angle?"

was correct. Including the table of G-loading for various bank angles and L/D ratios. The decrease in G-loading (or lift force) due to the flight path through the airmass being descending, not level, is very small for typical sailplane glide ratios, but it is still very real and fundamental to understanding the theory of gliding. And yes you are absolutely right of course, on my last post I meant to type "glide angle" not "glide ratio". Glide ratio (in still air) would be simply L/D. If you are defining lift correctly. If you are using lift to mean the total VERTICAL aerodynamic force, than you can no longer say that the still-air glide ratio equals the L/D ratio. The L/D ratio and the W/D ratio are very close to each other, for flat glide angles, but they are not exactly the same.

OK, enough on that. Really!

S

It's good to know I can reduce my G-loading by opening the spoilers, or dropping the landing gear.

Holding your breath does the same thing.
Try it, you'll feel lighter.
Jim

On Wednesday, June 10, 2015 at 9:19:14 PM UTC-7, jfitch wrote:

It's good to know I can reduce my G-loading by opening the spoilers, or dropping the landing gear.

"Holding your breath does the same thing.
Try it, you'll feel lighter.
Jim "

Wow! That really works, just tried it hear in my chair!

"Holding your breath does the same thing.
Try it, you'll feel lighter.
Jim "

Wow! That really works, just tried it here in my chair!

What's wrong?!? I did it, but right up until I turned blue and passed out, I
actually felt heavier...air from the big breath I took first?

It is always amusing listening to pilots discuss aerodynamics.

It's proof that the monkey does not need to know how the machine works, as long as they know what button to push and when.

I'll remember to use the breath hold in the future.

Todd Smith
3S
Educated and practicing aeronautical engineer.

On Thursday, June 11, 2015 at 1:44:11 PM UTC-4, wrote:
It is always amusing listening to pilots discuss aerodynamics.

It's proof that the monkey does not need to know how the machine works, as long as they know what button to push and when.

I'll remember to use the breath hold in the future.

Todd Smith
3S
Educated and practicing aeronautical engineer.

Such an individual has no place on this site!
UH

It's always good to consider extreme cases.

Consider a terminal velocity dive, where the flight path is vertical.

I stand by every word I've said so far, so I won't say them again.

I get the impression some folks are reading this in the form of individual emails and missing the context of the whole thread? Because points that have already been answered keep getting raised over and over again. Here is the whole thread: https://groups.google.com/forum/#!to...ng/svCmIstyZPU

S

The only caveat I'll add (again repeating something said already) was that I'm using G-loading to mean lift force / weight. That's quite close to what we'll read on a panel-mounted G-meter. I won't quarrel if you want to use G-loading to mean something else, that's fine, there is at least one other very reasonable definition of G-loading, but if the parameter of interest is lift force or lift force/ weight, then absolutely you do it reduce it, in the long run (steady-state case), by deploying spoilers or landing gear.

Again consider the terminal velocity vertical dive-- what will your panel-mounted G-meter read?

Why people are suddenly talking about airmass movement is beyond me-- I wasn't.

S