Dream Time -- Little help here?

"Richard Kaplan" wrote
Just recently I saw a "stormscope" in a magazine devoted to Park and
Recreation Department people. It's designed to allow Park and Rec
directors
to close/open outdoor events when storms get close by.

Not even close in performance to an aviation panel-mount Stormscope or
Strikefinder.

What makes you say that? If the unit he's talking about is the one
I've seen, I certainly don't agree.

Michael

"Jim Fisher" wrote in message
...

So, if this is what you are comparing a "real" Stormscope to then I would
have to agree.

That is more or less what I am assuming the portable device is, or at least
I would expect comparable performance.

The reason I am assuming this is because I have never seen or read about an
acceptable portable antenna for any sferics device. If I am wrong and
someone out there has indeed invented a portable sferics antenna with
acceptable performance, please let me know.. if so, I think such a device
would sell for about 1/2 the cost of an existing spherics device, not 10% of
the cost.



--
Richard Kaplan, CFII

www.flyimc.com

"Richard Kaplan" wrote in message
The reason I am assuming this is because I have never seen or read about
an
acceptable portable antenna for any sferics device.

I really have no doubt that this gadget doesn't rival the performance of a
14k unit but, like you, I have nothing to base this on but the thought that
"it can't be as good 'cause it ain't as expensive and it doesn't have
'Airplane Use Only' printed on it."

However, the old Stormscope I had in my Cherokee had a cool, colorful little
led-based, radar-like screen. It would tell you if a strike was between 0
and 30 miles, 30 and 60 and 60 to 90 miles out. It also gave you a general
idea of the direction from which the strike was detected in ~25 degree
increments. This thing supposedly added $3,500 bucks to the Trade-a-Plane
value of my plane when I sold it.

I didn't use it for "serious" IFR because, number one, I wasn't IFR rated
and, number two, even if I was I would never attempt to fly in any "serious"
IFR with embedded CB all around me where I would actually need such a gizmo.
I only found it comforting to have in the panel in case I ever needed it to
get my ass out of a sling some day.

It was nothing like the newfangled gizmos that plot a little lightning bolt
in the exact range and direction of your position.

My point is that this handheld gizmo would just HAVE to give me at least as
much info as my old Stormscope--which wasn't much but would probably come in
handy if I ever needed it.

I'll dig up that magazine and post the name of it here when I get a chance.

--
Jim Fisher

"Jim Fisher" wrote in message
...

increments. This thing supposedly added $3,500 bucks to the Trade-a-Plane
value of my plane when I sold it.

I am comparing it to a $3000 or so used Strikefnder or Stormscope.


It was nothing like the newfangled gizmos that plot a little lightning bolt
in the exact range and direction of your position.

The "newfangled gizmos" -- even the $14,000 ones -- still are not accurate
enough to plot your way through embedded storms. They are most useful in
steering you to areas where storms are absent -- and a used $3000
Strikefinder/Stormscope does that just almost as well as the new $14,000
units.

Spending $14,000 on a Stormscope makes no sense IMHO...a better plan would
be to spend $3,000 on a used Stormscope and then spend the difference on a
weather datalink system which includes data from the national lightning
detection network.


My point is that this handheld gizmo would just HAVE to give me at least
as
much info as my old Stormscope--which wasn't much but would probably come
in


A Strikefinder or Stormscope -- any age, any model -- is most helpful when
it is blank. They tend to be quite accurate in determining storm direction
but poor in determining distance. However, when a Stormscope or
Strikefinder of ANY vintage shows a blank screen then you can be very
confident that there is no convective activity within the range of this
sferics device.

I think a better analogy is that this gizmo would just HAVE to give you at
least as much information as an ADF -- while an ADF can indeed point to
thunderstorms, I certainly would not use an ADF to verify the *absence* of
thunderstorm activity, and I doubt this portable device would be that
reliable or sensitive either.

The bottom line is that an old Stormscope or Strikefinder may not be
terrific at telling you where thunderstorms ARE, but they sure are
outstanding at telling you where thunderstorms are ABSENT. I doubt this
portable device could determine the absence of thunderstorms with the same
level of sensitivity.

--
Richard Kaplan, CFII

www.flyimc.com

"Richard Kaplan" wrote
The "newfangled gizmos" -- even the $14,000 ones -- still are not accurate
enough to plot your way through embedded storms. They are most useful in
steering you to areas where storms are absent -- and a used $3000
Strikefinder/Stormscope does that just almost as well as the new $14,000
units.

I think that's conditionally true. With a good installation, the
older technology is really just as good. With a poor one, it's not.
Mostly, I disagree about the use of the device to plot a course
through embedded T-storms.

Anyone who understands how an ADF works will intuitively understand
how the bearing portion of a sferics device works. Range is more
difficult.

The most primitive way of determining range would be signal
instensity. Unfortunately, a strong but distant discharge would have
the same intensity as a weak but close one. Therefore, to have any
hope of determining range at all, you have to do better than that.
Manufacturers are notoriously closed-mouthed about the methods they
use, but really anyone who designs electronic equipment for a living
(which I do) can figure it out. Basically, a distant but strong
signal will show 'spread' - it doesn't all happen at once. A local
but weak discharge will be much 'tighter.' These fine points of
signal shape will be largely lost if the way the antenna is installed
causes significant signal distortion. Largely but not totally -
sufficiently good signal processing will be able to recover a lot.
Thus the newer sferics devices are less sensitive to installation
error. Not a big deal if you have a good friend who is an expert on
such things to help you put one in, but worth the extra money if the
installation will be done by an avionics shop technician.

In any case, the device will suffer from radial spread. In fact, when
it shows a lightning strike, an older unit will show it as multiple
dots along a radial. Any distance information thus derived is
approximate - factor of two at best. A later strike, unless it is
directly ahead, will be along a different radial line. If you're
flying an honest heading and constant airspeed, you can use the
elapsed time between strikes and the change in the angle to estimate
the range to the cell quite accurately.

Of course this assumes that there is plenty of room (10-20 miles)
between cells. If you're going to try to make it through the 2-3 mile
soft spots between cells, you need RADAR.

Spending $14,000 on a Stormscope makes no sense IMHO...a better plan would
be to spend $3,000 on a used Stormscope and then spend the difference on a
weather datalink system which includes data from the national lightning
detection network.

$3K for a used Stormscope with installation is doable, but just so you
understand, an avionics shop will generally bill $50-$75 per shop
hour. I will pay a GOOD electronic technician (one who can actually
troubleshoot and understand the concepts involved) $50K+ and bennies
to work in a nice, air conditioned environment rather than crawling
under the dash of a Mooney. You do the math. On the other hand, if
you can find an installer who really knows what he's doing, it makes a
lot of sense.

However, when a Stormscope or
Strikefinder of ANY vintage shows a blank screen then you can be very
confident that there is no convective activity within the range of this
sferics device.

That's very true, and maybe useful in some parts of the country. Here
on the Gulf Coast, it's a rare summer day when you see a blank screen.

I think a better analogy is that this gizmo

I think you need to be more specific about which gizmo. I've seen one
sold in one of the 'scientifics' magazines (maybe Edmund's) that went
for about $500. It gave very accurate bearing, and range about as
accurate as a Stormscope. To tell you the truth, I could build one
today that would sell at that price if I could move a few tens of
thousands a year. DSP's are cheap these days.

There is also another gizmo out there, goes for about $150, been
around much longer, and really only measures intensity. Pretty
useless, IMO - not much better than an ADF.

BTW - this is an excellent reason to retain the ADF in the IFR panel,
especially an older all-analog model. To an extent, it backs up the
Stormscope. The way to get best performance is to tune to a locally
unused frequency, and then use the test circuit to point the needle to
the tail. If the needle stays put, you are generally OK - any
activity that may be present is mostly behind you.

I doubt this
portable device could determine the absence of thunderstorms with the same
level of sensitivity.

I think that depends on which device you're talking about. Three
years ago I would have agreed with you. Not anymore.

Of course that doesn't mean that even the more modern gadget is usable
in an airplane. The problem is that there never was, and probably
never will be, a usable sferics antenna that can be placed INSIDE a
metal cage. That means the antenna that comes with the gizmo would
have to be installed - and I'm betting nobody is going to sign off on
that in a certified airplane. On the other hand, in an experimental
there's no longer any good reason to pay for a certified unit.

Michael

"Michael" wrote in message
om...

Of course this assumes that there is plenty of room (10-20 miles)
between cells. If you're going to try to make it through the 2-3 mile
soft spots between cells, you need RADAR.

Oh, boy, now there is a jump... from a VFR pilot to flying embedded
thunderstorms at a 2-3 mile range.

No thank you, in fact not for me either, not even with Strikefinder plus
RDR160 radar plus CBAV aboard... I keep at least a nice 25 miles from all
sferics hits. I still have "only" a piston airplane and the speed/climb
performance just are not there to escape if the door closes behind me.


in an airplane. The problem is that there never was, and probably
never will be, a usable sferics antenna that can be placed INSIDE a
metal cage. That means the antenna that comes with the gizmo would
have to be installed - and I'm betting nobody is going to sign off on


Exactly my point (though stated much better...thank you)... therefore no
portable "gizmo" will match the performance of a used
Stormscope/Strikefinder and in fact no such "gizmo" is likely to even come
close.

--
Richard Kaplan, CFII

www.flyimc.com

Sorry this is a tad late (7 days).How about this:

Buy an old Suburban or a pickup truck with a large gas tank - pickups used
to have second gas tanks, do they still?...something that burns regular
(whatever). Pump from the large gas tank(s) in the truck over to the plane.
Arrive on Full and leave the airport on E in your vehicle. Fill up on the
way home. No extra "fuel tank" in the bed of your truck. You need an small
electric pump (with flow meter) and a good strainer - that's it. Oh, some
grounding clips might not be a bad idea either ...g.

With the right truck, maybe 35 or 40 gallons per "swap". Anyone do this???

Speaking of trucks, my local county is having a vehicle auction in a few
weeks - I'm going to see what the "auction" prices are for a used van/truck
for a beater second vehicle. Sold the 1989 Motel Probe this past week, need
another vehicle out here in the burbs.

--
Montblack

(Cory wrote)
snipped
I'm pretty sure the new Nazi airport manager would have kittens if I tried
to use/store a fuel truck/trailer on the line. Still thinking about how to
do it for cheap. If I could easily filter the 6-gal containers to get the
small amount of sediment and water out of it, I probably wouldn't even
bother with trying to do it bulk.

"Newps" wrote in message
...


Montblack wrote:
Sorry this is a tad late (7 days).How about this:

Buy an old Suburban or a pickup truck with a large gas tank - pickups
used
to have second gas tanks, do they still?...something that burns regular
(whatever). Pump from the large gas tank(s) in the truck over to the
plane.
Arrive on Full and leave the airport on E in your vehicle. Fill up on
the
way home. No extra "fuel tank" in the bed of your truck. You need an
small
electric pump (with flow meter) and a good strainer - that's it. Oh,
some
grounding clips might not be a bad idea either ...g.

With the right truck, maybe 35 or 40 gallons per "swap". Anyone do
this???

Your problem will be flow rate. If it takes a long time to transfer 40
gallons it will lose its appeal rather quickly. I would guess that
about 8 gpm would be a bare minimum.

I have seen 'real' fuel trucks for auction on EBay. Don't see one offhand
currently. There is this:
http://cgi.ebay.com/ebaymotors/ws/eB...m=2423009 415 Not sure what the flow rate would be, probably need a pump?