[Mavi Gogun]

Tightening the sail reduces twist in the wing, presenting more of the wing simultaneously at a flying attitude. So, doesn't this mean that the slowest min sink (not "air speed") a glider is capable of may be had with the VG fully pulled, sail tight?

[tom emery]

Sounds right to me. (14 solos, low air time.)
On another note, could you explain "polar"?
I keep hearing this word and although I have an idea of the definition, I am still not clear.
Thanks.

[Mavi Gogun]

[tom emery]

I am currently flying without an airspeed indicator. I notice most pilots also fly without one. So, is this "polar" more of a template of the design charictaristics set down on paper as opposed to actual speeds you should "best" fly the glider?
Is the airspeed indicator coupled with a thorough understanding (memorization) of the "polar" going to help make me a better pilot, or is it more of a general layout of the handling characteristics of the glider?
I was told that an indicator was not really necessary. More important to listen and feel the wind.

[Mavi Gogun]

[psuguru]

[Jason]

even on a T2c i don't think its really necessary to use the polar, the absolute best still air glide you would get is about 15:1....... and in any kind of sink headwind that is going to drop rapidly and you will be able to see/judge your glide if you are anywhere near the ground..

as to the original question, when i flew torrey in my sensor i found i would get higher with the VG full tight.....

[ChattaroyMan]

[Mavi Gogun]

[Lucky_Chevy]

Based on my experience VG does not significantly impact the minimum sink of the glider. It is a tool to improve your best glide performance.

Very little is gained If you pull on full VG and fly at trim. For my glider, full VG and pulled in 3-4" will give me best glide. Performance will vary considerable based on glider design and glider loading.

Of course that's just my opinion....I could be wrong

[Hangskier]

Here's a question? And I know gliders differ, but in general, modern advanced king post or topless glider...... Is best glide achieved by 1/2 VG pulling in 5-6" or 3/4 VG pulling in 4-5" or full VG pulling in 3-4", or does speed play more of a roll?

[AIRTHUG]

VG is not as complicated as you guys are making it sound...

VG pulls the sail tighter by spreading the crossbars, widening the nose angle, and giving you (slightly) more span.

A tight wing with very little twist and more span is more efficient than a washed out wing, loose sail, and less span.

Look at a Sport 2 and a U2 and you can see the difference.

Now... the part that gets tricky is that the wing gets harder to control with more VG. If you have too much and can't fly it straight (either roll or yaw) you'd be better served with less VG. The wing will still be less efficient, but if you can fly it straight the end result will net better performance.

One other caveat- on some gliders the trim speed changes as you pull VG and remove washout. Min sink is usually about as slow as you can go before the onset of stall. Not actually stalling, just the onset of stall, where the first portion of the wing stops flying. There's usually a yarn tuft in this spot and you should be able to see it in flight. On these gliders with transient trim, you might have to push out a little to fly min sink. At this speed and this much VG, the glider will be basically uncontrollable... so again, maybe it's not the most efficient in the end.

But in terms of aerodynamics... full VG is the most efficient your wing will get- AT ANY SPEED....

[FormerFF]

[Bobfly]

I use a hall airspeed indicator on my Freedom and one thing it did help with was when I slowed to trim speed or just above it (the bar was still pulling out slightly) I was at 15mph. The wing appeared to fly quite happily at that speed but I have been told it should trim around 17mph meaning I need to move the hang point forward to tune for my weight. Never would have known that without the asi. It's a good cheap investment. It's also good to know exactly what speed your wings stall occurs at.

[tom emery]

Thanks everyone for the helpful information. Think I'll get me an ASI, study polars for the Wills Wing Falcon III 195 and try to maximize my airtime.

[AIRTHUG]

[danmoser]

There is a certain optimum amount of wing twist which minimizes induced drag at a given angle of attack.
So the general trend is:
To get the lowest sink rate (high angle of attack), use a greater amount of twist.. in other words, looser VG.
To get the best glide at high airspeeds (low angle of attack), it is advantageous to use less twist -- that is -- VG tight.
Where the exact VG setting lies to get the absolute lowest sink rate is different for each pilot/glider combination.

At VG tight, some of the hotter wings are stall/spin-prone when flying slow, and turning becomes more difficult at all airspeeds.
So, scratching next to the hill in punchy lift with one of these wings should NOT be done with tight VG, as it is easier to lose control of the glider's direction at the very time when you have the least amount of room to recover.
Chances are the looser VG settings are giving you just as good or better minimum sink rate anyway, so you get spin resistance & better handling for free !!.

Highly skilled pilots might get away with scratching at VG tight .. but make no mistake.. there is a much slimmer margin for error !!!.. and the Earth shall rise up and smite thee.