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

On Saturday, January 9, 2016 at 11:14:07 AM UTC-6, Dan Marotta wrote:
Hi Kirk,



Yes, I've towed you during at least one contest at Moriarty and I've
admired your LS-6.



Please understand that I don't "poo-poo" Flarm in my comments, I
only respond to the comments of some, which I believe are
unreasonable or downright wrong.* I always welcome logical proofs
like the math-based analysis of the pull-up (in a previous thread).



And yes, I think Flarm is a great tool for situational awareness but
I don't think that knowing a blip's ID is a requirement for safety.*
And I'm neither for nor against "stealth" mode - I don't care either
way.* The idea of coordinating an escape plan with another aircraft
5 miles away by radio is simply ludicrous.* Remember when contests
were fully manned and there was no Flarm or GPS?* I'm not against
either, as a lot of the folks here think, but I think a lot of the
fun has gone and that's the main reason I don't fly contests any
more.



So why do I keep posting?* It's out of a genuine concern that false
perceptions, unchallenged, will eventually become policy, and I
don't want any more policies.


Dan, by all means keep on posting - we need some grown-up input here now and then! But seriously, I haven't been convinced by any of the pro-stealth arguments. I would argue we should go the other way - full tracking of ALL contestants, shown in the cockpit, and let everyone share the info from all.. This may come from my sailing experience (racing Lasers), where you are immersed in the fleet, know who the hot shots are, and can see who is benefiting from wind changes, lulls, etc - all of which makes the race a much more involving event, and from my dislike of "OLC racing", which I find pretty boring (aside from not being racing in the real sense, IMO).

But then, I like the company of other gliders when I race - I must be channeling some residual Red Flag memories ;^).

Cheers,

Kirk
66

On Friday, January 8, 2016 at 11:03:36 PM UTC-5, Dan Marotta wrote:
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

Dan, I specifically asked to keep this thread clean from any comments not related to finding a solution. Please take your comments to another thread and argue there. These comments bring no value towards finding a solution. This thread was intended to bring people together to find a solution not to create another divide.

To all, let's not get engaged in questioning each other motives.

Regards,
Andrzej

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?

On Friday, January 8, 2016 at 5:36:33 AM UTC-8, wrote:
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

A little math would help - but this seems roughly right.

Any decending air outside a thermal would likely be more gentle than the rising air at the core. I have certainly found I could gain more than 1,000 feet within 15 or 20 seconds with a smooth pull-up into a strong thermal.

We are talking about having adequate closing time (of around 45 seconds) from first being put on the traffic screen until potential collision - and not being . A glider running in say 3 knots of sink at 110 kts will lose around 500 feet in 45 seconds and a glider pulling up into lift might gain 7-800 from the pull-up and another 3-500 from the lift over that time period for a total of 1500-1800 feet net change (assuming the run into the thermal didn't also have some lift). Anything less creates a scenario where you can sneak in outside of the altitude filter for stealth and come into view with less than the requisite 45 seconds. Less than 1200 or so and the surprise can be quite sudden - maybe 8-10 seconds.

Of course getting into lines of lift can yield many different scenarios - running storm shelves is a common tactic, but so is convergence and occasionally wave - all have pairings of strong lift and some level of sink and pairings of gliders maneuvering. The fact that sink tends to generate push-overs and lift tends to generate pull-ups means that the effects are amplified, rather than canceling, so you need to look at both together.

9B

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.