required LD versus required MC to make it home ??

You guys need to distinguish two separate uses of the flight
computer.

1. How to use it to maximize speed on the final glide, with an
acceptable small risk of landing out in friendly terrain short of the
airport, costing you only contest points and a few beers for your crew

2. How to use it to gauge safety glides, where speed is not so much an
issue, but making really really sure you make it to the destination is
important.

For 1, Andreas has it exactly right, even at Minden. If you're in a 5
knot thermal, yes, you will do better climbing to the correct height
and blasting home at the 5 knot Mc speed -- if you dare. Try it some
time. It's a lot of fun to let your buddy leave, fly home at 80 knots,
while you climb high, blast home at about 115 and catch him a few
miles from the airport.


For 2, thermal strength is not really an issue. If there were a
thermal of decent strength, you'd take it! The issue is proceeding or
turning back. Here is where you evaluate the wisdom of gliding on with
substantially higher Mc values than the weakest thermal you'd take
(anything!) and substantially higher values than correspond to the
speed you're going to glide back at. Just how much higher should that
MC value (or bugs if you like) be? That depends on just how bad the
terrain is below, and also on the chance of finding significant sink
on the way. Again, smoother air means less risk.

John Cochrane

On Aug 24, 3:44*pm, Ramy wrote:
On Aug 24, 11:33*am, Andreas Maurer wrote:



On Tue, 24 Aug 2010 11:09:01 -0700 (PDT), Ramy
wrote:

Seems like many pilots are using multiple complicated methods to
determine their final glides. Most are using MC settings for that
purpose. Is it just me who never use MC setting to determine arrival,
but using bug factor instead? Following the KISS principal, this is
the simplest way. No need to compare L/D, guesstimate MC, disconnect
the vario or ignore the MC speed to fly, etc. Just set your bug factor
to degrade your polar to something you are comfortable with (I found
70-75% to work fine most of the time), set your MC to zero and watch
your arrival altitude. Once you are comfortable with the arrival
altitude just keep maintain the same number by either speeding up or
slowing down. Works perfect for me.

... but is neither accurate, nor fast, not safer.

Most pilots don't want to waste time (or simply don't have the
weather) to climb extremely high in the last thermal, hence they
follow McCready's advice that has been proven for the last 50 years:
Set the average climb rate of the last thermal as MC setting, add the
bug factor, and leave the thermal once the arrival altitude is to your
liking. Works like a charm, and is extremely easy to use.
To be honest, I have difficulties to find an explanation why something
different (your settings, for example) should be less complicated.

What you are doing is simply to abandon the performance of your 56:1
ship and fly it like a 30:1 Ka-6. Works, but is far, far away from the
optimum.

Cheers
Andreas

Nope. We both are going to leave the thermal at the same time and
glide at the same speed.
In my case the MC will be zero and the bug factor 75%, in your case
MC=3 and bug factor = 95-100%.
However you will need to ignore the speed to fly as John suggested
unless you are willing to risk landout to save couple of minutes
(which may make sense only in contest).
Using the last average climb in the thermal is often meaningless in my
opinion. In many places I fly (Truckee, Hollister, Byron), the last
average thermal is maybe 5 knots but the next is zero since this was
the last thermal. This is true for many soaring sites which are in the
valley and not on the top of the montain range you just left, as well
as long XC flight where the likelyhood to find another thermal late in
the day is small. So using the method of dialing MC = last average
climb and then follow STF is guaranty landout, and a very silly one...
So my recomendation to all non contest XC pilots will be to degrade
your performance using bug factor 70-75%, which will give you enough
buffer for unexpected sink or head wind (which can also be very
different from the wind measured in your last turn) and fly MC=0 until
you are comfrtable with your arrival altitude and then speed up if
your arrival altitude start increasing. This will usually result in
slower glide speed at the beginning of the final glide, gradually
increasing as you get closer, much safer than the other way around.

Ramy

Only a smallish fraction of my flying is in contests, but whenever I'm
on cross country I aim to go fast. MC 0 is almost always a poor speed
to fly, unless you're positive you won't see any more lift and you
want
to go as far as absolutely possible (to pick up a few points in a
contest
or for an easier retrieve, e.g., which aren't really very good
reasons).
Reichmann points out that MC 1 is a better setting if you are in
desparation mode, because you give up only a little glide distance
but you get to sample more air in a given time.

As far as flying final glide, the correct speed to fly is the ultimate
strength of your last thermal. If you were climbing at 5 knots (20s
avg)
in a thermal that had averaged 2.5 knots from when you started (e.g.
it
was narrow down low and it took a while to get going), and you could
make it home with MC 2.5, you will finish quicker if you continue to
climb until you can get home at MC 5.

As far as safety in final glides, John Cochrane has a good paper on
that.
I ensure safety by flying to a safety altitude at finish. If I'm not
going to
make that I stop and climb or land out when I still have time to do it
safely.
When I do go to a contest I'm safer for having practiced how to do
that.

Now, for a beginner at cross country, it's great to be conservative.
You've
never landed out, so worrying about being too far away is a stress
factor.
Reduce that by practicing your off field landing skills at home on
every
landing so you're confident when it happens for real. Sooner or later
that
will happen, even if you're on a "local" flight. I had a friend do
that while
taking his wife on a sightseeing flight! You won't make enemies if
you
exercise good judgment on the day you're caught away from the field
and put it down safely someplace.

-- Matt

On Aug 24, 1:11*pm, mattm wrote:

Reichmann points out that MC 1 is a better setting if you are in
desparation mode, because you give up only a little glide distance
but you get to sample more air in a given time.

Are you sure about that? MC=0 will give you more time and more air to
sample (beeing the best L/D speed) than MC=1. I always use MC=0 when I
switch to survival mode unless I am also battling significant head
wind.

Ramy

On Aug 24, 4:44*pm, Ramy wrote:
On Aug 24, 1:11*pm, mattm wrote:

Reichmann points out that MC 1 is a better setting if you are in
desparation mode, because you give up only a little glide distance
but you get to sample more air in a given time.

Are you sure about that? MC=0 will give you more time and more air to
sample (beeing the best L/D speed) than MC=1. I always use MC=0 when I
switch to survival mode unless I am also battling significant head
wind.

Ramy

Yes, it's true. It's on the last page of this paper:
http://www.dragonnorth.com/djpresent...ss_country.pdf

"A lot of pilots flew and fly unnecessarily low average
speeds when they get low, because they are anxious
and fly with a zero setting. They don’t know that with a
setting at 1 knot they have almost the same glide angle
and lose much less average speed in case they recover
and complete the task."

In my plane (ASW-19) MC=0 speed is 53kts, and L/D is 38:1.
MC=1 speed is 61kts, and L/D is 35:1. Granted my sink rate
is about 30fpm faster, but I'll have almost 20% greater range to find
that thermal I need to get back up again.

-- Matt

On Aug 24, 1:44*pm, Ramy wrote:
On Aug 24, 1:11*pm, mattm wrote:

Reichmann points out that MC 1 is a better setting if you are in
desparation mode, because you give up only a little glide distance
but you get to sample more air in a given time.

Are you sure about that? MC=0 will give you more time and more air to
sample (beeing the best L/D speed) than MC=1. I always use MC=0 when I
switch to survival mode unless I am also battling significant head
wind.

Ramy

Depends on your objective. If you want to absolutely minimize chance
of landout and are certain you are not going to run out of time before
the lift dies, Mc = 0 is a better bet. If you care about speed around
the course or are worried about the end of useful lift at the end of
the day you should be willing to give up a little search range to gain
speed towards the goal (this presumes you search in direction of the
goal when you get desperate - also important if you are speed or time
constrained)

9B

On Aug 24, 2:54*pm, mattm wrote:
On Aug 24, 4:44*pm, Ramy wrote:

On Aug 24, 1:11*pm, mattm wrote:

Reichmann points out that MC 1 is a better setting if you are in
desparation mode, because you give up only a little glide distance
but you get to sample more air in a given time.

Are you sure about that? MC=0 will give you more time and more air to
sample (beeing the best L/D speed) than MC=1. I always use MC=0 when I
switch to survival mode unless I am also battling significant head
wind.

Ramy

Yes, it's true. *It's on the last page of this paper:http://www.dragonnorth.com/djpresent...training_for_c...

"A lot of pilots flew and fly unnecessarily low average
speeds when they get low, because they are anxious
and fly with a zero setting. They don’t know that with a
setting at 1 knot they have almost the same glide angle
and lose much less average speed in case they recover
and complete the task."

In my plane (ASW-19) MC=0 speed is 53kts, and L/D is 38:1.
MC=1 speed is 61kts, and L/D is 35:1. *Granted my sink rate
is about 30fpm faster, but I'll have almost 20% greater range to find
that thermal I need to get back up again.

-- Matt

Matt I'm afraid you missunderstood Reichmann comment. He claimed that
you will lose less average speed with MC1 which is true. But you will
not gain 20% greater range. On the contrary, Your search range will
always be less if you fly faster than MC=0 (unless you have
significant head wind which requires flying faster than best L/D).
Bottom line, as other pointed out, it all depends on your goal. If you
are flying contest, in which every second counts, then flying correct
MC is important. If you fly for OLC or distance, like I believe the
majority of XC flights are, and your main objection is to make it back
home at the end of the day (as the subject lline says), than fly MC 0
when you are in survival mode or starting your final glide.

Ramy

On Aug 24, 5:06*pm, Ramy wrote:
On Aug 24, 2:54*pm, mattm wrote:



On Aug 24, 4:44*pm, Ramy wrote:

On Aug 24, 1:11*pm, mattm wrote:

Reichmann points out that MC 1 is a better setting if you are in
desparation mode, because you give up only a little glide distance
but you get to sample more air in a given time.

Are you sure about that? MC=0 will give you more time and more air to
sample (beeing the best L/D speed) than MC=1. I always use MC=0 when I
switch to survival mode unless I am also battling significant head
wind.

Ramy

Yes, it's true. *It's on the last page of this paper:http://www.dragonnorth.com/djpresent...training_for_c...

"A lot of pilots flew and fly unnecessarily low average
speeds when they get low, because they are anxious
and fly with a zero setting. They don’t know that with a
setting at 1 knot they have almost the same glide angle
and lose much less average speed in case they recover
and complete the task."

In my plane (ASW-19) MC=0 speed is 53kts, and L/D is 38:1.
MC=1 speed is 61kts, and L/D is 35:1. *Granted my sink rate
is about 30fpm faster, but I'll have almost 20% greater range to find
that thermal I need to get back up again.

-- Matt

Matt I'm afraid you missunderstood Reichmann comment. He claimed that
you will lose less average speed with MC1 which is true. But you will
not gain 20% greater range. On the contrary, Your search range will
always be less if you fly faster than MC=0 (unless you have
significant head wind which requires flying faster than best L/D).
Bottom line, as other pointed out, it all depends on your goal. If you
are flying contest, in which every second counts, then flying correct
MC is important. If you fly for OLC or distance, like I believe the
majority of XC flights are, and your main objection is to make it back
home at the end of the day (as the subject lline says), than fly *MC 0
when you are in survival mode or starting your final glide.

Ramy

But, but, but, (and I think I can hear John Cochrane pounding his head
on his desk in Chicago...) when about to go on final glide and you are
in that last thermal you know what the theoretical final glide Mc
should be. And by all means factor in safety margins but if you have a
climb significantly over your Mc="0" value then keep climbing and bump
the Mc appropriately to match that climb. I mean why not? I know
sometimes pilots like to float past the home airport and stretch a few
more OLC miles then turn back. Personally the call of that cold beer
makes me want to fly that final glide as fast as possible.

What is really annoying about arguing with Ramy on this point (which I
think I've done before) is no matter what I can argue on paper I have
no hope of keeping up with him in practice.

Sigh

Darryl

On Tue, 24 Aug 2010 17:06:17 -0700 (PDT), Ramy
wrote:

Matt I'm afraid you missunderstood Reichmann comment. He claimed that
you will lose less average speed with MC1 which is true. But you will
not gain 20% greater range. On the contrary, Your search range will
always be less if you fly faster than MC=0 (unless you have
significant head wind which requires flying faster than best L/D).

What Matt wanted to say (and what Reichmann said) is that the loss of
L/D is negligible if you fly MC1 (compared to MC0), therefore your
chances to catch a thermal are hardly affected, but IF you catch a
thermal, you will have lost lots of time if you flew MC0 instead of
MC1.



Bottom line, as other pointed out, it all depends on your goal. If you
are flying contest, in which every second counts, then flying correct
MC is important. If you fly for OLC or distance, like I believe the
majority of XC flights are, and your main objection is to make it back
home at the end of the day (as the subject lline says), than fly MC 0
when you are in survival mode or starting your final glide.

In one word:
No.
Even on a normal XC flight average speed counts - you want to be back
before the thermals die.

There's one basic rule in XC flying:
Use MC0 only if you are very, very, very desperate.
For me this starts at 1000 ft above the ground with no thermal in
sight.


Cheers
Andreas

On Tue, 24 Aug 2010 12:44:22 -0700 (PDT), Ramy
wrote:


Nope. We both are going to leave the thermal at the same time and
glide at the same speed.

Not at all.
You leave the thermal at a height that is dictated by a relatively
crude estimation of your glider's performance.
I leave the thermal at an altitude that is the optimum for a given
climb rate, wind vector and glider performance.

Guess what's more effective.


However you will need to ignore the speed to fly as John suggested
unless you are willing to risk landout to save couple of minutes
(which may make sense only in contest).

Not at all.
Flying my STF will always get me to the airfield as long as there is
no significant air mass sink. It's as safe as your proposed MC0
approach in any way. Usually even safer because an MC2 or higher
setting for the final approach usually dictates a higher climb in the
last thermal and higher STF than your MC0, resulting in more energy
reserves. And yet it's faster, too.


Using the last average climb in the thermal is often meaningless in my
opinion.
So using the method of dialing MC = last average
climb and then follow STF is guaranty landout, and a very silly one...

Nope.. it's not. These rules have been proven over and over again, and
with a little experience in XC gliding (say, ten years), you'll find
that these rules really work as advertized.


So my recomendation to all non contest XC pilots will be to degrade
your performance using bug factor 70-75%, which will give you enough
buffer for unexpected sink or head wind (which can also be very
different from the wind measured in your last turn) and fly MC=0 until
you are comfrtable with your arrival altitude and then speed up if
your arrival altitude start increasing. This will usually result in
slower glide speed at the beginning of the final glide, gradually
increasing as you get closer, much safer than the other way around.

Well... safety-wise both methods are identical.
How do you fly on a long XC flight? Which MC do you use?


Cheers
Andreas

On Aug 24, 12:08*am, Eric Greenwell wrote:
On 8/23/2010 8:17 AM, akiley wrote: Well, I've flown long enough to know not to trust electronics. *I have
600 power hours using all sorts of navigators. *Funny, when you use a
Garmin 396 on a computer, it sets magnetic variation to user set
instead of auto. *SeeYou has quite a few bugs and gochas too. *So my
primary is look at the down angle back to the airport.

I've used SeeYou Mobile for 1000+ hours all over the USA, and I'm not
aware of any bugs or gotchas. I would never go back to paper charts,
whiz wheels, or just looking out the window. For example, most of my
final glides begin 30 to 50 miles from the airport, where I can't even
see it, yet they work out well most of the time.
Eric,
What happens if your electronics fry? Hope you have a backup
something. Just happened to a friend of mine, he found a 5 year old
WAC chart under his seat. I'm not going back to paper charts either,
I'm just saying for me, I'm going to back it up with something, even
if it's a quick math in the head thing. There are plenty of gochas I
can think of is SeeYouM. All you have to do is not double check what
your goto waypoint is, forget to add winds, polar, safety altitude.
Maybe they aren't gochas, but they sort of are for new users. It
takes a lot of thinking to make sure you know what you are doing.

I have the latest version of SeeYouM that I bought last fall. One
known bug is that the wing loading changes when you leave the polar
screen then come back. Try it. I think they fixed the one with Oudie
that didn't allow the user to set NM in units. You would have to
reset it every time you loaded SeeYouM. I haven't gotten an answer on
my Magnetic Track NavBox yet. It's off by 12 degrees. Maybe it's
party to do with old PDA hardware but I've had a lot of problems with
logging not starting, and NavBoxes showing no data, and lockups.
Other have had these problem too. Some days my statistic page that is
supposed to show thermal graphs doesn't.

I'm slowly replacing components of my iPaq to see if that's the
problem. I just replaced the CF card adapter back, I've tried a
different CF card. We'll see.

I'm definitely a navigator user. I have a Garmin 395, I've put quite
a lot of hours on Garmin G1000's in IFR flight. My point is one has
to be careful throwing full trust into these things. My SeeYou
experience has had a bad start, but I'll get it nailed down
eventually. I really enjoy analyzing my IGC file on my PC after the
day is done. In playback mode on the iPaq too, that is a learning
experience too. ... akiley

Your statement "So my primary is look at the down angle back to the
airport" suggests to me it's not SeeYou, but more likely your setup or
interpretation of what Mobile is telling you. If you are that close, the
computer should be working with no problems.

Flight computers can be a real aid to efficient, enjoyable soaring, so I
hate to see someone having problems with them. What version of mobile
are you using? Can you describe the two biggest bugs and gotchas?

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarmhttp://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz