PowerFlarm and ADS-B solution, can we find one?

On Wednesday, January 6, 2016 at 12:03:56 PM UTC-8, Dan Marotta wrote:
Protocol - it's there for a reason.* I understand coordinating in a
thermal, e.g., "BD, I'm inside your turn at 5 o'clock low", but
calling someone almost a mile away and suggesting that he make a
turn so as not to collide with me when I can simply make my own turn
doesn't make sense.



Do you really need information on another aircraft within 300 meters
vertical spacing from you?* That's almost 1000 feet!* IFR and VFR
traffic routinely pass each other head on, over taking, and at
oblique angles with only 152 meters (500') vertical separation.* I
can understand your concerns in and around thermals, but not in
cruise.


Am I mistaken or did you post that you do not have a Flarm and do not plan to purchase one?

You are correct. I do not have a Flarm and do not plan to purchase one,
though that could change if only there were not so many wild claims,
suggestions, scare tactics, calls for mandatory use, etc.

I only posted to this thread because of the illogic of some of the
claims and the outright falsity of others. Without going to the
calculus, I'll challenge anyone here to gain 1000' in a pullup in a
glider from 140 KIAS without performing some sort of unusual attitude
recovery afterwards.

Before retiring I worked as a systems engineer for 35 years so I know
something about specifying, designing, building, integrating, testing,
and delivering complex systems and, frankly, a lot of claims and
suggestions made here are just hogwash. You may now flame away - I'm
through trying convince some of you that the world is, indeed, round
(sorta).

On 1/6/2016 5:16 PM, Jonathan St. Cloud wrote:
On Wednesday, January 6, 2016 at 12:03:56 PM UTC-8, Dan Marotta wrote:
Protocol - it's there for a reason. I understand coordinating in a
thermal, e.g., "BD, I'm inside your turn at 5 o'clock low", but
calling someone almost a mile away and suggesting that he make a
turn so as not to collide with me when I can simply make my own turn
doesn't make sense.



Do you really need information on another aircraft within 300 meters
vertical spacing from you? That's almost 1000 feet! IFR and VFR
traffic routinely pass each other head on, over taking, and at
oblique angles with only 152 meters (500') vertical separation. I
can understand your concerns in and around thermals, but not in
cruise.

Am I mistaken or did you post that you do not have a Flarm and do not plan to purchase one?

--
Dan, 5J

On Wednesday, January 6, 2016 at 7:36:27 AM UTC-8, Dan Marotta wrote:
In the spirit of technical discussion I must point out what seems to
me to be a basic flaw in logic.



The statement that you can gain or lose altitude at 10 m/s (~20 kt)
is certainly valid in the US southwest.* However the supposition
that two gliders traveling in opposite directions with 200 meter
vertical separation would be at risk of collision due to one
suddenly dropping and the other suddenly climbing in the same
airmass does not appear to be a serious risk.*

I think the idea is that they'd be in *different*, adjacent airmasses. Where you have strong lift you tend to have similar sink adjacent to the lift, this is true for wave, convergence and thermals. It's one reason why it's common to push over when exiting a thermal, so you can quickly traverse the sinking air surrounding the thermal (what goes up comes down somewhere nearby - that way all the air doesn't end up above the boundary layer). I've gained 1,000' pulling up in strong lift and I've seen similar opposite situations thunderstorm shelf-running. The climbing and descending gliders would not be maneuvering in the same thermal to be sure as it's hard to imagine in that case the pushing over into sink glider and the pulling up in lift glider doing anything other than diverging, but one glider pushing over to get through a veil of rain and sink while another glider is just pulling up into the strong lift under the shelf just beyond. You'd like to see that guy coming rather then letting him sneak in below the Stealth invisibility cloak and pop up into a conflict. Maybe it's just me, but I don't like surprises.

Part of the challenge with selectively degrading a device like Flarm is making sure you haven't made an assumption about the scenarios that can (or can't) come up.

9B

On Thursday, January 7, 2016 at 6:20:32 PM UTC-8, Andy Blackburn wrote:
On Wednesday, January 6, 2016 at 7:36:27 AM UTC-8, Dan Marotta wrote:
In the spirit of technical discussion I must point out what seems to
me to be a basic flaw in logic.



The statement that you can gain or lose altitude at 10 m/s (~20 kt)
is certainly valid in the US southwest.* However the supposition
that two gliders traveling in opposite directions with 200 meter
vertical separation would be at risk of collision due to one
suddenly dropping and the other suddenly climbing in the same
airmass does not appear to be a serious risk.*

I think the idea is that they'd be in *different*, adjacent airmasses. Where you have strong lift you tend to have similar sink adjacent to the lift, this is true for wave, convergence and thermals. It's one reason why it's common to push over when exiting a thermal, so you can quickly traverse the sinking air surrounding the thermal (what goes up comes down somewhere nearby - that way all the air doesn't end up above the boundary layer). I've gained 1,000' pulling up in strong lift and I've seen similar opposite situations thunderstorm shelf-running. The climbing and descending gliders would not be maneuvering in the same thermal to be sure as it's hard to imagine in that case the pushing over into sink glider and the pulling up in lift glider doing anything other than diverging, but one glider pushing over to get through a veil of rain and sink while another glider is just pulling up into the strong lift under the shelf just beyond. You'd like to see that guy coming rather then letting him sneak in below the Stealth invisibility cloak and pop up into a conflict. Maybe it's just me, but I don't like surprises.

Part of the challenge with selectively degrading a device like Flarm is making sure you haven't made an assumption about the scenarios that can (or can't) come up.

9B

Some people do push over in lift, and nearly everybody pulls up in lift. If you are near cloud base in a thermal and you expect sink in the ring around it (very common), a correct strategy is to turn sharply 180 degrees from the intended departure direction and dive through the core so that you have maximum speed gain with minimum loss to traverse the sink. This is exactly when a glider entering is pulling up. 1000 ft is nothing in this scenario.

On Thursday, January 7, 2016 at 10:24:34 PM UTC-5, jfitch wrote:
a correct strategy is to turn sharply 180 degrees from the intended departure direction and dive through the core so that you have maximum speed gain with minimum loss to traverse the sink.

No.

T8

On Thursday, January 7, 2016 at 10:24:34 PM UTC-5, jfitch wrote:


Some people do push over in lift, and nearly everybody pulls up in lift. If you are near cloud base in a thermal and you expect sink in the ring around it (very common), a correct strategy is to turn sharply 180 degrees from the intended departure direction and dive through the core so that you have maximum speed gain with minimum loss to traverse the sink. This is exactly when a glider entering is pulling up. 1000 ft is nothing in this scenario.

That is so George Moffat 70's right out of Winning on the Wind.
There is very rarely an improvement in speed made good by some very dynamic exit of a thermal. The case that would favor it is very strong lift surrounded by strong sink.
A better technique is to use the lift at the end of the climb to smoothly accelerate the glider to the desired speed before hitting the sink. Rarely would this require more than a few hundred feet at most. Modern gliders get up to speed with very little loss of altitude.
What you are describing may be fun but it is not very efficient.
Pull ups obviously can and are more dynamic but even there smoothness pays off. UH

On Friday, January 8, 2016 at 5:36:33 AM UTC-8, wrote:
SNIPThe case that would favor it is very strong lift surrounded by strong sink.

There ya go: +10 followed by -10 not that uncommon here. The tradeoff between altitude and speed is mathematically fixed by classical physics: 1st law of thermo which I think everybody believes. It hasn't changed since the 70s (or even the 1770s). Drag of sailplanes has reduced very slightly in 45 years, which affects it very slightly. 90 knots speed reduction (from 140 - 50) is around 700 ft. (minus energy lost due to inefficiency, but plus gain due to 10 knot thermal). Pushover form 50 - 140 is the same, reversed.

No, I would not do that on a day with 2 knot thermals topping at 2500 ft. But I assume we want a Flarm stealth solution that works in all conditions?

I'm with you, T8.

I read this exact strategy back in the 80s; I think it was in
Reichmann's book. I couldn't wait to perform a Split-S through a
thermal. I was a new guy and thought that would be cool. The "come to
Jesus" meeting at the end of the day with the other occupants of the
thermal was, shall we say, enlightening.

So here's my take on this whole Flarm "stealth" thing:

Those who want stealth mode, don't want others to be able to identify
them and become remoras. That seems a nicer word than leeches. They
state the reasons for their opposition in clear terms.

Those who don't want stealth mode want to be remoras but don't want to
admit it. In an attempt to push their view, they fall back on Mom,
apple pie, children, lawyers, and safety. We see the same arguments all
the time in other activities and they become more unlikely and extreme
with each round.

On 1/8/2016 3:59 AM, Tango Eight wrote:
On Thursday, January 7, 2016 at 10:24:34 PM UTC-5, jfitch wrote:
a correct strategy is to turn sharply 180 degrees from the intended departure direction and dive through the core so that you have maximum speed gain with minimum loss to traverse the sink.
No.

T8

--
Dan, 5J

On Thursday, January 7, 2016 at 10:24:34 PM UTC-5, jfitch wrote:
On Thursday, January 7, 2016 at 6:20:32 PM UTC-8, Andy Blackburn wrote:
On Wednesday, January 6, 2016 at 7:36:27 AM UTC-8, Dan Marotta wrote:
In the spirit of technical discussion I must point out what seems to
me to be a basic flaw in logic.



The statement that you can gain or lose altitude at 10 m/s (~20 kt)
is certainly valid in the US southwest.* However the supposition
that two gliders traveling in opposite directions with 200 meter
vertical separation would be at risk of collision due to one
suddenly dropping and the other suddenly climbing in the same
airmass does not appear to be a serious risk.*

I think the idea is that they'd be in *different*, adjacent airmasses. Where you have strong lift you tend to have similar sink adjacent to the lift, this is true for wave, convergence and thermals. It's one reason why it's common to push over when exiting a thermal, so you can quickly traverse the sinking air surrounding the thermal (what goes up comes down somewhere nearby - that way all the air doesn't end up above the boundary layer). I've gained 1,000' pulling up in strong lift and I've seen similar opposite situations thunderstorm shelf-running. The climbing and descending gliders would not be maneuvering in the same thermal to be sure as it's hard to imagine in that case the pushing over into sink glider and the pulling up in lift glider doing anything other than diverging, but one glider pushing over to get through a veil of rain and sink while another glider is just pulling up into the strong lift under the shelf just beyond. You'd like to see that guy coming rather then letting him sneak in below the Stealth invisibility cloak and pop up into a conflict. Maybe it's just me, but I don't like surprises.

Part of the challenge with selectively degrading a device like Flarm is making sure you haven't made an assumption about the scenarios that can (or can't) come up.

9B

Some people do push over in lift, and nearly everybody pulls up in lift. If you are near cloud base in a thermal and you expect sink in the ring around it (very common), a correct strategy is to turn sharply 180 degrees from the intended departure direction and dive through the core so that you have maximum speed gain with minimum loss to traverse the sink. This is exactly when a glider entering is pulling up. 1000 ft is nothing in this scenario.

i know thats what moffat says to do.... but that's not a good maneuver if you are sharing the thermal.

On Friday, January 8, 2016 at 11:56:50 AM UTC-8, ND wrote:

i know thats what moffat says to do.... but that's not a good maneuver if you are sharing the thermal.

Which is why I started with "someone who thinks they are alone in the thermal might" (if you look up thread little further).

It is perhaps another east/west divide thing that need to be considered in any solution. The thermals in the west can be very strong, as the sink can also be, and speeds are quite high by comparison. I'm not sure the same parameters are going to apply to both, as others have also suggested. That means, without further epiphanies, two stealth modes.