| Lee H. Marzke on 19 Jul 2017 17:48:22 -0700 |
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| Re: [PLUG] Waaaaay Off Topic: Thunderstorm Movement |
----- Original Message -----
> From: "Rich Freeman" <r-plug@thefreemanclan.net>
> To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
> Sent: Wednesday, July 19, 2017 12:40:24 PM
> Subject: Re: [PLUG] Waaaaay Off Topic: Thunderstorm Movement
> On Wed, Jul 19, 2017 at 12:12 PM, Lee H. Marzke <lee@marzke.net> wrote:
>>
>> As a glider pilot - I knew Monadnock was causing it
>
> I never hit anything like what you did, but it was hard enough just
> trying to descend into Queen city over the nearby ridge. It was a
> fairly windy day so it was hard to lose altitude even on idle with
> flaps, or at least it seemed that way. Plus it was quite bumpy.
> Bumpy enough for me. 70 degrees of roll would have probably made it
> my last flight. :)
I had taken an aerobatic intro flight a few years prior in a Decathlon, and
was allowed to do a loop, and roll a few times myself so the bank didn't
bother me too much. I just worried about how long I could fly in this turbulence
without getting sick. That's the only time while flying turbulence that really bothered me.
What I also wanted to do on my Decathlon aerobatic flight was inverted flight, and to steer towards a point
on the ground inverted, as I couldn't figure out how that worked. In normal flight, When you bank right , the
nose goes right, however it turns out when inverted, and you bank right, the nose goes left ! That
screwed up my mind until figued it out.
When your flying normally the lift vector is straight up, and banking right tips the lift vector
to the right , so the airplane turns right. Inverted, the lift vector is straight down toward the
sky ( on the horizon view in front of you, ground is above, and sky below the horizon ) So when banking right, the
lift-vector actually tips towards your left side (beneath you), and the nose is pulled left. It is
kind of creepy.
>
>> With good lift the cumulus bottoms are often dark and slightly concave, and
>> gliders
>> steer towards those clouds to better find good lift. Haven't heard of the LCL.
>
> I won't elaborate much since wikipedia does well, but it seems to be
> approximately what you were describing:
> https://en.wikipedia.org/wiki/Lifted_condensation_level
>
> I've also heard it called the "lower condensation level" or "cloud base."
>
> That said, after reading a bit more about LCL and LFC I suspect my
> understanding is a bit flawed here, and I really need to brush up on
> this stuff. I'm not sure that air will naturally rise to the LCL
> unless forced. It looks like air will naturally rise if it is above
> the LFC.
>
>>
>> In the US you can't often legally climb into the cloud in controlled airspace-
>> so your stuck at 500ft below
>> cloudbase, unless you climb up the side the cloud like I described in that
>> frontal wave - which is very rare.
>>
>
> When would you ever be allowed to legally climb into a cloud, barring
> some kind of emergency situation? I'd think that you'd be subject to
> the VFR minimums in general, unless people fly gliders under IFR or in
> class B airspace.
Yes you must maintain basic VFR cloud clearances, and you might get a Letter-of-Agreement
(LOA) from ATC for your glider club for flights in wave-window boxes into Class A
( above 18,000 ). There are also transponder requirements these days for
flight in basically all controlled airspace - but gliders are exempt ( for now)
except inside Class A, B,C, or above the lateral limits of Class B,C.
( For other reading:
Class A is above 18,000 MSL across US, for mostly Jets and requires an IFR clearance
Since we have high speeds and variable weather - all aircraft up this high are under positive IFR control.
Class B is the classic 20NM diameter upside down wedding cake Airspace around the busiest Airports for
controlling all traffic ( both IFR and VFR )
Class C is for a bunch of smaller busy airports with Jet traffic ( like Allentown )
Class D is around other small airports with operating control Towers
Class E is keep VFR aircraft out of certain approach areas around airports when the weather
is bad and IFR aircraft are flying in that area without visual references. You don't
have to have a clearance or talk to anyone, just don't scud run in Class E in bad weather
because you might bump into someone IFR.
Class G is uncontrolled - and very little of this exists each of the Mississippi except small
slices less than 1200 AGL away from all airports )
Basically no IFR aircraft would ever be here.
)
One such wave window LOA is here:
http://www.kingmountaingliderpark.com/sailplane-wave-agreement/
Well, Class B (like around Philly ) allows you to fly "Clear-of-clouds" instead of standard 500/1000/2000 ft
below/above/horizontal distances, but glider can't enter Class B today except in an
emergency anyway.
Flying in the Clouds ?
If your caught above a cloud layer - you'll need to come down through it. That
most commonly happens when you fly Mountain Wave up to high altitudes, and the moisture
increases then the cloud cover below closes the cloud gap ( wave window ) too fast for
you to descend through it.
That is a true emergency , since most typical gliders do not have
even a turn&bank gyro, so you can't maintain flight for long in the clouds and will most often
enter a graveyard spiral. The recommended emergency descent through a cloud layer without a
gyro is to enter a spin ( which IS stable in most gliders ), and hold the spin until you break
out of the bottom of the cloud, and then recover from the spin. OK, not sure I really want
to do that maneuver. I'm OK with spins when I can see but not in a cloud.
Here's a video for you: Spectacular Glider ground winch launch, 45 degree steep climb, followed by
search for lift, a loop, a spin, a few wing-overs, and landing in 5 min. Winch launch is not
common in the US because a steel cable going from the ground up 1500 feet over an airport is
frowned upon by non glider pilots. And the falling cable ( with small drogue ) can be dangerous.
But it is 100X cheaper than a tow.
https://www.youtube.com/watch?v=dGKwKLb4jwI
And another of a Blanik L-13 with great Music and traditional aerial launch (tow)
https://www.youtube.com/watch?v=2uMZ9w7tbgc
The handle on the far left in cockpit during TO roll are the spoilers. Appears he is using them
during TO to avoid climbing; then as the Tug lifts off, he pushes spoilers full forward closed and locked.
It is bad news to climb before the tug lifts off as you can lift the tug's tail and keep him from
taking off. In the US we just push the glider nose down to stay low - as the glider lifts off
much sooner than the tug. On tow this shows the front flying far to the left of the 'box' on tow, which can
be a signal to the tug to turn right, or can be just training. It is interesting that
during takeoff the spoiler handle goes forward by itself, so its the rear pilot ( crazy guy ) that is actually
flying the Take-off, and later the front pilot takes over and flies to the left of the box.
This L-13 is the original earlier model of the L-23, flown here with the rear canopy removed and a
crazy guy jumping off the wing in flight.
Back to your question, To legally fly in clouds you need to be rated, equipped and current. The Glider may
be IFR certifiable since many are European made, but the US grants pilots an Instrument-airplane ratings, and not
Instrument-Glider ratings as far as I know. Currency requires 6 IFR approaches every 6 months- and your not going
to get that in a glider, so I guess no IFR glider in the US.
Lee
>
> --
> Rich
> ___________________________________________________________________________
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--
"Between subtle shading and the absence of light lies the nuance of iqlusion..." - Kryptos
Lee Marzke, lee@marzke.net http://marzke.net/lee/
IT Consultant, VMware, VCenter, SAN storage, infrastructure, SW CM
___________________________________________________________________________
Philadelphia Linux Users Group -- http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug