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Wonder Boy
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PostPosted: Wed Sep 02, 2015 6:37 am    Post subject: Reply with quote #21   
waveview wrote:
Wonder Boy wrote:
waveview wrote:
Vario lag is 1-3 seconds * so a 360 rotation in 7 seconds would have the vario signal to the pilot a massive 60-140 degrees out when trying to center the lift Sad

How do pilots compensate for vario lag when they are thermaling at fast/slow 360's?

* http://www.ddsc.org.au/documents/manuals/Basic%20Instrument%20Explanations.pdf


You're vario lag should not be 1-3, sounds like it's broken.


Mike, the vario is one of the quality name brand models popular in hang gliding.

Placed the vario at floor level then lifted it quickly up over my head to a complete stop. The vario has STOPPED climbing at this point but the audio climb sound continued at a reducing tone for 4.8 seconds. Do other vario's do this?


Mine does not do that. I'm using a flytec 6030, I can check what my dampening settings are when I get home.
(Almost 5 seconds after you stopped is ridiculous)

Mine will beep maybe .5 seconds after I stop

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Wonder Boy
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PostPosted: Wed Sep 02, 2015 6:38 am    Post subject: Reply with quote #22   
Tormod wrote:
Varios have adjustments ranging from "nervous" to what you describe, time to read the manual!


Exactly

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red
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PostPosted: Wed Sep 02, 2015 7:58 am    Post subject: Bank angle and time to complete a 360 Reply with quote #23   
Tormod wrote:
Varios have adjustments ranging from "nervous" to what you describe, time to read the manual!
Campers,

That is true, for many of the newer variometers. This "slow" setting may be okay for well-experienced pilots,
but it can be an obstacle to a new pilot trying to get airtime.

http://user.xmission.com/~red/#vs

Personally, I do not fly with a "slow" vario, because a quick response rate helps me to core a thermal,
and to work with "random" lift that has no visible causes.

Mr. Green

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waveview
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PostPosted: Tue May 16, 2017 5:28 am    Post subject: Reply with quote #24   
Thermal flying can be very confusing unless the pilot gets a handle on vario lag and sensitivity settings. This recent discussion in the Oz report shows the debate is still on - It appears that other people have noticed that many vario's continue to indicate lift for a few seconds, even once the climb rate has dropped to zero.
http://ozreport.com/blog.php


Link

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Karl_A
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PostPosted: Tue May 16, 2017 8:42 am    Post subject: Reply with quote #25   
You can observe a lot by watching. -Yogi Berra

A useful trick when you're on the ground is to pick a single glider - or bird - and watch it for several minutes. Don't take your eyes off it. Then you will see what it is really doing. Occasionally glancing at it isn't enough.
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peterkoistinen



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PostPosted: Tue May 16, 2017 9:22 am    Post subject: Reply with quote #26   
Andy,

you wrote

"Of course, with a flex wing you'll be able to make a smaller circle at a given bank angle than a rigid."

why?

are we assuming the flex is flying slower than the rigid?

(Recall that turn rate and radius depend only upon bank angle and true airspeed. For example, at 30 degrees bank and 150 mph, a B 52 will have same turn rate and radius as a Cessna 172.)

or is there another factor in the flex vs. rigid turn radius comparison?

I agree that it sure seems like the flex could turn tighter that the rigid, just not sure precisely why.

That being said, so far, for me, the superior sink rate of the rigid more than makes up for the larger turn.

Also that being said, with my ATOS VQ, I 'm fully on the dark side now and not looking back. My T2 is gone, sold , don't let the door hit you on the way out!

Pete
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NMERider
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PostPosted: Tue May 16, 2017 10:59 am    Post subject: Reply with quote #27   
peterkoistinen wrote:
....I agree that it sure seems like the flex could turn tighter that the rigid, just not sure precisely why....

Hi Pete,
Here's why:
RW has longer wingspan which results in greater airspeed differential between inside and outside wings.
RW has far less maximum washout which results in easier tip-stalls and spin entry and the lift distribution is more evenly spread out over the longer wingspan.
FW has VG which enables the pilot to increase washout and thus re-balance lift to concentrate more toward the center.
FW is flexible and under G-loading from turn bank angle the tips will increase washout in addition to any VG change made by pilot.
Cheers,
Jonathan

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Wonder Boy
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PostPosted: Tue May 16, 2017 10:51 pm    Post subject: Reply with quote #28   
RW dont turn very tight...... Rolling Eyes
I wish mine did Wink

(yes I know, but I posted a the pic and made the comment anyway)



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NMERider
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PostPosted: Wed May 17, 2017 6:32 am    Post subject: Reply with quote #29   
Wonder Boy wrote:
RW dont turn very tight...... Rolling Eyes
I wish mine did Wink....

I've seen video of the SR-71 at a steeper bank angle than that and it has relatively stubby wings yet the turning circle had to be measured in miles, not feet. But heck, that certainly is a pretty picture. thumbsup

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TjW
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PostPosted: Wed May 17, 2017 6:51 am    Post subject: Reply with quote #30   
NMERider wrote:
peterkoistinen wrote:
....I agree that it sure seems like the flex could turn tighter that the rigid, just not sure precisely why....

Hi Pete,
Here's why:
RW has longer wingspan which results in greater airspeed differential between inside and outside wings.
RW has far less maximum washout which results in easier tip-stalls and spin entry and the lift distribution is more evenly spread out over the longer wingspan.
FW has VG which enables the pilot to increase washout and thus re-balance lift to concentrate more toward the center.
FW is flexible and under G-loading from turn bank angle the tips will increase washout in addition to any VG change made by pilot.
Cheers,
Jonathan


It's simpler than that: they fly faster. Turn diameter is a function of speed and bank angle. That's because the wing lifts the airplane around the turn.
All the factors you mention may affect the minimum speed you're comfortable flying at, but they don't directly affect the turn diameter.
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peterkoistinen



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PostPosted: Wed May 17, 2017 7:06 am    Post subject: Reply with quote #31   
I was just about to write pretty much the same thing.

For the reasons Jonathan noted, in many cases the rigid must (or ought to) fly faster than the flex for a given bank angle. And it's strictly the airspeed and bank angle that will determine turn radius (and turn rate)

SR 71, what an awesome airplane! Yes it will have a HUGE turn radius, and a very slow turn rate; not because of stubby wings, but because of it's fast, fast, blistering, paint peeling, true airspeed.
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NMERider
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PostPosted: Wed May 17, 2017 10:14 am    Post subject: Reply with quote #32   
peterkoistinen wrote:
I was just about to write pretty much the same thing.

For the reasons Jonathan noted, in many cases the rigid must (or ought to) fly faster than the flex for a given bank angle. And it's strictly the airspeed and bank angle that will determine turn radius (and turn rate)

SR 71, what an awesome airplane! Yes it will have a HUGE turn radius, and a very slow turn rate; not because of stubby wings, but because of it's fast, fast, blistering, paint peeling, true airspeed.
Additionally, the ability of a flex wing hang glider to increase it's washout (twist) via VG rope or frame flex also allows it to make a tighter turn due to the curvature of the airflow when making a tight circle. A swept RW attempting the same turn will experience a much higher relative AoA at the tips which will cause the glider to either fight the turn or stall a tip even easier than before and enter a spin. The tightest measure climbing turn I have ever done in my T2C 144 were 58' in diameter at an estimated 70° bank angle and at ~44mph. Sadly, the shorter projected wing spans and slower thermalling speeds of modern comp PGs allows then to get better established in most cores and they climb right through me as if I were pole-sitting. But I live and fly in a high pressure environment which makes for some very skinny thermals.
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dayhead
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PostPosted: Fri May 19, 2017 3:49 pm    Post subject: Reply with quote #33   
I've noticed over the years that I tend to overestimate my bank angle. 45 feels like 60, 30 feels like 45. Or something like that.

If I'm not climbing as well as I think I should be, I'll remember this and I'll bank her up more. Once I get used to it, my shyness disappears.
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Tontar
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PostPosted: Tue May 23, 2017 7:32 am    Post subject: Reply with quote #34   
What's a vario? ;-)
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NMERider
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PostPosted: Tue May 23, 2017 8:21 am    Post subject: Reply with quote #35   
Tontar wrote:
What's a vario? ;-)
You know, like in 'Vario Geometry'. Laughing
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Jason
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PostPosted: Tue May 23, 2017 9:02 am    Post subject: Reply with quote #36   
NMERider wrote:
peterkoistinen wrote:
....I agree that it sure seems like the flex could turn tighter that the rigid, just not sure precisely why....

Hi Pete,
Here's why:
RW has longer wingspan which results in greater airspeed differential between inside and outside wings.
Cheers,
Jonathan


thats only true up to 45 degrees, once you exceed 45 degrees the diffrence in tip speeds starts to decrease, by the time you get to 70-80 degrees the difference is nearly 0.
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NMERider
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PostPosted: Tue May 23, 2017 9:07 am    Post subject: Reply with quote #37   
Jason wrote:
NMERider wrote:
peterkoistinen wrote:
....I agree that it sure seems like the flex could turn tighter that the rigid, just not sure precisely why....

Hi Pete,
Here's why:
RW has longer wingspan which results in greater airspeed differential between inside and outside wings.
Cheers,
Jonathan


thats only true up to 45 degrees, once you exceed 45 degrees the diffrence in tip speeds starts to decrease, by the time you get to 70-80 degrees the difference is nearly 0.
Isn't >45° just a little bit beyond most relevant soaring conditions?
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Jason
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PostPosted: Tue May 23, 2017 9:08 am    Post subject: Re: Bank angle and time to complete a 360 Reply with quote #38   
waveview wrote:
After reading a thermal flying guide * that said pilots often don't bank their gliders steep enough in 360 turns while thermaling. The article went on to say that the best indication of bank angle is the amount of time it takes to complete one 360 degree turn . Higher bank angles mean faster , tighter 360's I guess.

So is there an optimum bank angle for hang gliders while flying thermals?

* http://www.sac.ca/website/index.php/fr/documents/cdn-advanced-soaring/319-thermalling/file


to answer the original question
generally the lower you are the tighter the turns need to be. thermals tend to expand as they increase in altitude (and get smoother)
so between them being smaller and nastier down low its a good idea to start steep and then widen as you go.
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Charlie Romeo
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PostPosted: Wed May 24, 2017 2:31 am    Post subject: Reply with quote #39   
Hi again Waveview,well i guess there's not much for me to add from the good and varied advice you have garnered here except to say as many before me said too...to always fly with some helpful experienced mates who are willing to be watchful as you happily expand your skill set.A good mate on the ground is an even better mate in the air.You learn a lot after many decades of hg and we shouldn"t mind passing on our tricks and tips and stuff ups! A lot may hear but only some will listen Rolling Eyes.If an up and coming pilot out flys me in years to come i figure i"ve done a good job Cool The two excellant links posted by Piano Man were the only two i read, however the in depth discussion by James Freeman was spot on...ps I tested my Brauniger 6005 IQ+ at three quarters sensitivity and it over ran for about one to one and a half secs.
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Jason
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PostPosted: Wed May 24, 2017 6:56 am    Post subject: Reply with quote #40   
NMERider wrote:
Jason wrote:



thats only true up to 45 degrees, once you exceed 45 degrees the diffrence in tip speeds starts to decrease, by the time you get to 70-80 degrees the difference is nearly 0.
Isn't >45° just a little bit beyond most relevant soaring conditions?


NMERider wrote:
The tightest measure climbing turn I have ever done in my T2C 144 were 58' in diameter at an estimated 70° bank angle and at ~44mph. Sadly, the shorter projected wing spans and slower thermalling speeds of modern comp PGs allows then to get better established in most cores and they climb right through me as if I were pole-sitting. But I live and fly in a high pressure environment which makes for some very skinny thermals.


also your math doesn't add up
58 foot diameter=29 foot radius, 44mph=65 fps
a=v^2/r, for a lateral accelration of 4.5 gees

70 degrees of bank produces 2.92 felt gees and 2.75 lateral gees.

for the math to work you'd have to be around 78 degrees- for a felt gee load of 4.8 gees

i don't have the video of it now, but i remember flying the G103 and i obviously wasn't at 90, but it sure felt that way, maybe 70-75, with the stick fully back in my lap and going up with the vario pegged.

sometimes the steeper you bank the faster you climb
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