In wave, in blue hole at cloud level, hole closes, in IMC, then what?

On Wednesday, April 8, 2015 at 9:04:03 PM UTC-7, Darryl Ramm wrote:
On Wednesday, April 8, 2015 at 8:37:02 PM UTC-7, Tango Eight wrote:
This thread is off the rails. OP posed a scenario involving IMC in smooth lift at low speed. Now guys are complaining that some of the tips given won't work at redline in rough air. Well that's true. It shouldn't really be a surprise now, should it?

-Evan Ludeman / T8

And the scenarios were folks are breaking gliders in wave, at least in the big Sierra wave are just not that scenario, so it's not particularly interesting to other folks here, who may be trying to get the topic on a rail relevant to actual problems experienced in real wave flying ... :-) Well stuff that has at least eaten two gliders in the Reno areas.

The Sierra wave scenario is really being closed in IMC near VNE in smooth air (if bombing along you are maybe 10,000'or so higher than the rotor). No turbulence necessary to have a very bad day.

It has not been mentioned in this thread that VNE at the high altitudes associated with wave flight (at least the Sierra wave) is lower than the placard says. This is because flutter speed increases at a slower rate than TAS compared to IAS. Many don't know/remember this. In my glider, the placard VNE is 146 knots IAS but at 18,000 ft this is reduced to 122 knots IAS, at 30,000 less than 100 knots.

On Wednesday, April 8, 2015 at 12:02:26 PM UTC-7, Martin Gregorie wrote:
On Wed, 08 Apr 2015 11:41:01 -0600, Bob Whelan wrote:

In re Bob K.'s and Steve L.'s comments elsewhere on this branch, "Ha ha
ha. Oh the knowing joy of those familiar with 90-degree landing flaps
(and I'm one of 'em)!!!" Regrettably (in subsequently broken
ship/traumatized pilot terms), that particular religious war was lost
long, long ago.

Around 2004 there was another benign spiral thread which caused me to be
a bit of experimenting in an ASW-20. I found that, in calm evening air
trimmed for best glide (57 kts) and zero flap (position 3) and flying
straight, it slowly developed a 25 second phugoid oscillation with an
associated +/- 5kt speed oscillation.

I also tried for a benign spiral: zero flap, wheel down and brakes out,
same trimmed speed and going hands free after setting up a 20-30 degree
bank. After even half a circle the bank angle had increased, the nose had
dropped the speed was increasing. I never let it go beyond that point and
concluded that the ASW-20 doesn't have a benign spiral.

I haven't tried either experiment with the Libelle but should do so this
season, as its always good stuff to know. BTW, my H.201 is s/n 82, so it
dates from before the move to the B series, so it has balsa sandwich
flying surface skins, the small tailplane and upper and lower surface
brakes.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Martin,
I have H201 SN 81 and it will do a beautiful benign spiral! I've had "hands off" for 15-20 minutes when descending from altitude.
Love the Libelle!
Jay

On Wednesday, April 8, 2015 at 11:37:02 PM UTC-4, Tango Eight wrote:
OP posed a scenario involving IMC in smooth lift at low speed. Now guys are complaining that some of the tips given won't work at redline in rough air.

On Thursday, April 9, 2015 at 12:04:03 AM UTC-4, Darryl Ramm wrote:
so it's not particularly interesting to other folks here, who may be trying to get the topic on a rail relevant to actual problems experienced in real wave flying ...

The Sierra wave scenario is really being closed in IMC near VNE in smooth air (if bombing along you are maybe 10,000'or so higher than the rotor). No turbulence necessary to have a very bad day.

OP here. I'm happy to see discussion of the Sierra Wave scenario, but the scenario I posed is closer to the wave flying that I do in Vermont.

I'm flying in 'baby wave' at 50-60 knots to maintain position in the lift, maybe a little faster if I need to crab north or south to stay above the changing blue hole below. I may fly at Vno when I'm diving through the blue hole. I'm not flying XC and not anywhere near Vne. I can even stay close to the airport. When I'm ready (if ever) for something considerably more difficult, I'll go to the Mount Washington Wave Camp in NH.

It is not the Sierra wave or Mount Washington, but it is still risky. It is often 'wet', the blue holes are smallish, they open, close and move around.. The rotor can become unflyable (while you are still on the ground or above the cloud deck) and one expects rotor in the landing pattern, strong crosswind and sink on final. Landing at 70-80 knots is standard fare.

WRT turbulence in the cloud deck layer, my understanding is that the air in that layer is smooth since the cloud is formed by the laminar flow of air. The cloud forms where it hit the high pressure isobar and dissipates at the low pressure isobar. Basically smooth air, no convection... Am I wrong about this? So assuming not, descending through the cloud deck with a benign spiral seems plausible. Avoiding terrain is a issue and a moving map seems prudent. There is a good possibility of clear air above the valley floor, but the cap cloud likely touches the upwind ridge.

Below the solid cloud deck, there are rotor clouds and turbulence a plenty, and the gamble is that one pops out of the cloud deck between the rotor clouds. When that happens I'll be flying at 50-60 knots unless I get spit out of a rotor cloud and into a spin.

I'd only add, regarding your benign spiral scenario, that you'll be
traveling down wind at the velocity of the wind. Because of that, your
vertical speed will be increasing and decreasing (even gaining altitude
as you pass through rising and sinking air) and you may well break out
of the clouds a ridge or two downwind of your field.

Circumstances vary but, when I'm trying to get down from wave, I fly
slow and draggy rather than fast and clean (near Vne). That way, when I
hit the rotor (out west it's often in clear air) it won't be such a bad
experience.

BTW, having all my wave experience in Colorado and New Mexico, your
description of eastern wave sounds intimidating!

On 4/9/2015 8:51 AM, son_of_flubber wrote:
On Wednesday, April 8, 2015 at 11:37:02 PM UTC-4, Tango Eight wrote:
OP posed a scenario involving IMC in smooth lift at low speed. Now guys are complaining that some of the tips given won't work at redline in rough air.
On Thursday, April 9, 2015 at 12:04:03 AM UTC-4, Darryl Ramm wrote:
so it's not particularly interesting to other folks here, who may be trying to get the topic on a rail relevant to actual problems experienced in real wave flying ...

The Sierra wave scenario is really being closed in IMC near VNE in smooth air (if bombing along you are maybe 10,000'or so higher than the rotor). No turbulence necessary to have a very bad day.
OP here. I'm happy to see discussion of the Sierra Wave scenario, but the scenario I posed is closer to the wave flying that I do in Vermont.

I'm flying in 'baby wave' at 50-60 knots to maintain position in the lift, maybe a little faster if I need to crab north or south to stay above the changing blue hole below. I may fly at Vno when I'm diving through the blue hole. I'm not flying XC and not anywhere near Vne. I can even stay close to the airport. When I'm ready (if ever) for something considerably more difficult, I'll go to the Mount Washington Wave Camp in NH.

It is not the Sierra wave or Mount Washington, but it is still risky. It is often 'wet', the blue holes are smallish, they open, close and move around. The rotor can become unflyable (while you are still on the ground or above the cloud deck) and one expects rotor in the landing pattern, strong crosswind and sink on final. Landing at 70-80 knots is standard fare.

WRT turbulence in the cloud deck layer, my understanding is that the air in that layer is smooth since the cloud is formed by the laminar flow of air. The cloud forms where it hit the high pressure isobar and dissipates at the low pressure isobar. Basically smooth air, no convection... Am I wrong about this? So assuming not, descending through the cloud deck with a benign spiral seems plausible. Avoiding terrain is a issue and a moving map seems prudent. There is a good possibility of clear air above the valley floor, but the cap cloud likely touches the upwind ridge.

Below the solid cloud deck, there are rotor clouds and turbulence a plenty, and the gamble is that one pops out of the cloud deck between the rotor clouds. When that happens I'll be flying at 50-60 knots unless I get spit out of a rotor cloud and into a spin.




--
Dan Marotta

Any comments on coming out of the could with an intentional spin (one-gravity load entered at slow speed)?

Assuming slowing down first, and with known good VMC below the clouds, are there any comments about coming out of IMC using an intentional spin? (understanding that maximum load during spins is 1-G)

On Thursday, April 9, 2015 at 11:11:14 AM UTC-4, Dan Marotta wrote:
I'd only add, regarding your benign spiral scenario, that you'll be
traveling down wind at the velocity of the wind...
your vertical speed will be increasing and decreasing (even gaining
altitude as you pass through rising and sinking air) and you may
well break out of the clouds a ridge or two downwind of your field.

Good point. I think that may be the fatal flaw in this approach. The downwind terrain is largely unlandable and you don't have the altitude below the cloud layer to travel very far to find a landing spot.


BTW, having all my wave experience in Colorado and New Mexico, your
description of eastern wave sounds intimidating!

What I described is 'wet wave'. It is seductive and beautiful especially when the sun rays poke through the blue hole into the mist below. Lots of rainbows. The last bits of fall foilage. The lenticulars are often not visible.

We also have drier wave days when the lenticulars are clearly visible from the ground and there is a lot more blue sky. I imagine that this is more like western wave.

I'm having second thoughts about whether I really want to go up through the blue hole above the cloud deck on 'wet wave' days. There's often secondary wave below the cloud deck and ridge lift, and it is awesome when the sun rays poke down through the blue hole.

With the understanding that a spin is a 1-G maneuver, and responding to the original post, with sufficient clear air below and after slowing down, are there any comments about leaving the cloud using an intentional spin?

I do have a comment about coming out of the cloud in a spin. How many times have you tried to sustain a spin in your glider? I would do this before I tried spinning out of a cloud. The reason is in some aircraft a spin will turn into a spiral dive. They look the same but spin recovery technique will not work recovering from a dive and the airspeed builds very fast in a spiral dive. First time this happened to me was a real eye opener, just because I have never considered the glider would transition from spin to spiral dive. I did recognize it right away and recovered no problem, but it got my attention as I had never considered this before. I was in very clear smooth air with lots of altitude. I know the POH for an ASG-29 says spins will turn into spiral dive in a few turns. Just know what your gliders does. When practicing spins I do not remember ever letting the spin go more than 2 revolutions, what if it takes 10 revolutions and on the 3rd revolution your glider spirals.

Good thread though with lots to think about.

On Thursday, April 9, 2015 at 11:31:55 AM UTC-4, wrote:
Assuming slowing down first, and with known good VMC below the clouds, are there any comments about coming out of IMC using an intentional spin? (understanding that maximum load during spins is 1-G)

Compared to the benign spiral, a deliberate spin has the advantage of being faster, so there is less time to drift downwind. Especially appealing if you're above the valley floor when you start the spin.

I know pilots who use the spin to descend through strong wave lift in VFR and they comment on how long it took them to descend to the desired altitude. So it may take a lot of turns to get down.