S-H Ventus light-bar flap position indicator

Some Venti (not all) featured an 8 position LED light-bar centered on the instrument panel hood which would identify flap position.

What "electronics" are used under the seat pan on the flap handle mechanism to "switch" the LEDs? Are there 8 individual reflective sensors reading the flap positions?

On Sunday, June 9, 2013 10:11:54 AM UTC-6, wrote:
Some Venti (not all) featured an 8 position LED light-bar centered on the instrument panel hood which would identify flap position.



What "electronics" are used under the seat pan on the flap handle mechanism to "switch" the LEDs? Are there 8 individual reflective sensors reading the flap positions?

It's a simple switch-resistor-LED for each flap position. If you plan to use the gliders 12V bus, the LED's need the resistor. (FWIW, non-rechargeable lithium cells output 3.7V which is just right for an LED without resistor as millions of key-ring flashlights show.)

I know of three switch possibilities - Micro Switches, magnetic reed switches and Hall Effect devices. I really don't like Micro Switches since they need mechanical contact and so tend to wear out and get out of adjustment. Magnetic reeds and Hall devices don't require physical contact as they use magnetism instead. Reeds are typically glass so have to be installed carefully but if they are potted in epoxy, they work well. Some Hall Effect devices are inherently binary and very rugged. Both are cheap. I think Paul Remde sells suitable reeds.

The idea is to epoxy a tiny but strong NdFeB magnet to the flap push-rod in a convenient place with the reeds or Hall devices positioned to detect the magnet as it goes by. Each flap position gets it's own reed or Hall device.

In my Ventus 2 there is a thin a fiberglass rod attached to the flap control rod. The thin fiberglass rod runs to a switch reading box behind the seat next to the wheel well where all the sensors are enclosed. I would guess there is a Hall switch magnet attached to the rod inside the box to activate each of the sensors. Designed like this you do not have to try and attach everything near the flap handle.

The flap indicator is one of the surprises that I have found I would hate to do without now.

A low tech system I have seen is to run a plastic or fiberglass rod forward to the panel from the flap control rod and put a mark or the rod and set up a scale on the panel. Pure mechanical with no electronics.

On Sunday, June 9, 2013 10:15:07 AM UTC-7, Bill D wrote:
If you plan to use the gliders 12V bus, the LED's need the resistor. (FWIW, non-rechargeable lithium cells output 3.7V which is just right for an LED without resistor as millions of key-ring flashlights show.)


An LED is a diode junction, forward voltage is around 0.7 to 1.1V typically. 3.7V will make a single diode glow very brightly for a very short time. Cheap flashlights usually have 3 or 4 LEDs in series to accommodate the higher voltage.

On my LAK-17a, the flap settings are engraved into the steel detent
ar: -1, 0, 1, 2, L

What could be simpler?

"Tim Taylor" wrote in message
...
In my Ventus 2 there is a thin a fiberglass rod attached to the flap control
rod. The thin fiberglass rod runs to a switch reading box behind the seat
next to the wheel well where all the sensors are enclosed. I would guess
there is a Hall switch magnet attached to the rod inside the box to activate
each of the sensors. Designed like this you do not have to try and attach
everything near the flap handle.

The flap indicator is one of the surprises that I have found I would hate to
do without now.

A low tech system I have seen is to run a plastic or fiberglass rod forward
to the panel from the flap control rod and put a mark or the rod and set up
a scale on the panel. Pure mechanical with no electronics.

On Sun, 09 Jun 2013 12:38:47 -0700, jfitch wrote:

On Sunday, June 9, 2013 10:15:07 AM UTC-7, Bill D wrote:
If you plan to use the gliders 12V bus, the LED's need the resistor.
(FWIW, non-rechargeable lithium cells output 3.7V which is just right
for an LED without resistor as millions of key-ring flashlights show.)


An LED is a diode junction, forward voltage is around 0.7 to 1.1V
typically. 3.7V will make a single diode glow very brightly for a very
short time. Cheap flashlights usually have 3 or 4 LEDs in series to
accommodate the higher voltage.

Look at the maximum current rating of the LEDs, assume the LED has no
resistance and calculate the series resistor value from R = V/I where I
is the maximum rated current for the LED in amps, V is the supply voltage
in volts and R is the inline resistor in ohms. Round the resistor UP to
the next highest standard resistor size and fit that resistor size in
series with each LED.

This will give near maximum brightness. Try doubling the resistor's value
if its too bright.


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

It all depends in where you have to look to confirm your flap setting. The flap indicator in the SH allows the pilot to confirm the flap setting and change it effectively on take-off roll without taking your eyes off the tow plane. In a thermal with other gliders I never have to look down to confirm what setting I am in. In the SH "a" models it is harder to see the flap handle location so the position indicator is even more helpful.

On 10/06/2013 04:29, Tim Taylor wrote:

... A low tech system I have seen is to run a plastic or fiberglass rod
forward to the panel from the flap control rod and put a mark or the
rod and set up a scale on the panel. Pure mechanical with no
electronics.

Very reliable. Ask any C-47/DC-3 pilot.

GC

I added flap guidance to a system which I built for my Ventus. A differential pressure sensor feeds airspeed to a small processor which drives a second column of LEDs. The left column displays the flap position I should be in and the right column shows which position I'm actually in. There was no need to display landing flap position. When thermalling, the system shows both the +1 and +2 LED so it's up to me to choose which I prefer. All I have to do is match LEDs.

http://thezivleys.com/gliderstuff/panel%20pic.jpg

The current version which I use is based off magnetic reed switches, but SH has changed to the use of a linear potentiometer to control their new flap display unit which is a small 1" square indicator which uses 7 segment LEDs to show flap position.


Mark




On Sunday, June 9, 2013 11:11:54 AM UTC-5, wrote:
Some Venti (not all) featured an 8 position LED light-bar centered on the instrument panel hood which would identify flap position.



What "electronics" are used under the seat pan on the flap handle mechanism to "switch" the LEDs? Are there 8 individual reflective sensors reading the flap positions?

Don't have to look. I start the takeoff roll at -1 and, as I get aileron
authority, it's simply, "click, click, click". That puts me into
thermalling flap for the tow.

Those are some spiffy setups with the LEDs, however, and, as a sometimes
geek, I may need to make one "just because"!


"Tim Taylor" wrote in message
...
It all depends in where you have to look to confirm your flap setting. The
flap indicator in the SH allows the pilot to confirm the flap setting and
change it effectively on take-off roll without taking your eyes off the tow
plane. In a thermal with other gliders I never have to look down to confirm
what setting I am in. In the SH "a" models it is harder to see the flap
handle location so the position indicator is even more helpful.