Today's Message Index:
----------------------
1. 02:40 AM - Re: Re: Stall Warner - switch problems (Ian Cook)
2. 04:23 AM - Re: Cheap chinese landing light (carlp101)
3. 05:11 AM - Re: Landing Light Positioning (John Wighton)
4. 05:21 AM - Re: Re: Cheap chinese landing light (William Daniell)
5. 05:58 AM - Re: Landing Light Positioning (carlp101)
6. 06:58 AM - Re: Mode S Hexidecimal code (carlp101)
7. 12:48 PM - Re: Stall Warner - switch problems (Kelvin Weston)
Message 1
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| Subject: | Re: Stall Warner - switch problems |
Bud,
Not very often I disagree with you, but the stall warning switch does
not work as you describe. Under normal flight the switch senses +VE pressu
re (connecting an ASI up to the stall system) both the A/C normal ASI and s
tall warning see almost the same pressure and read the same value. As the
angle of attack increases the air separation transition point (-VE pressure
moves down the leading edge) and it is this suction that operates the swit
ch as the stall is approached. With the trial ASI still connected, at this
point it reads zero or below with the ASI pointer on the stop. Next test fl
ight will be conducted with a +VE and -VE 5" water gauge connected to the s
tall system to measure the actual +VE and -VE pressures. This work is being
done as part of the Permit work for the UK MG test flight programme as the
LAA are insisting on a stall warning system on the motor glider. On trying
to use the standard EUROPA XS system we are having trouble getting the swi
tch to work consistently. Note: the wing LE profile of the MG is different
to the XS and the stall speed is much lower at 42 KIAS at max 1370 lbs lowe
r with the airbrake just cracked open. On my machine, the stall is very ben
ign with very little airframe buffet.
Regards
Ian Cook
G-CBHI MG
From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-serv
er@matronics.com] On Behalf Of Bud Yerly
Sent: 29 June 2017 03:23
Subject: RE: Europa-List: Re: Stall Warner - switch problems
Kelvin,
The switch is a pressure switch. With the relative wind nearly straight on
the air into the tube is under suction. The switch is assembled to the ho
se to the leading edge using its pressure side. The switch is normally ope
n so with suction on the tube, the light is off at low angles.
At about 14 degrees angle of attack the switch is now under pressure from t
he ram air. The switch is normally open and at about 3 inches of water ish
, the switch will close and allow current to flow to the light/horn.
Once you land, and the speed diminishes, the pressure drops and the switch
opens and the horn goes off.
Not rocket science.
See photo below:
Regards,
Bud Yerly[cid:image001.png@01D2F0C2.29A422B0]
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Window
s 10
From: Kelvin Weston<mailto:kelv@kdweston.biz>
Sent: Tuesday, June 20, 2017 5:03 PM
Subject: Europa-List: Re: Stall Warner - switch problems
o:kelv@kdweston.biz>>
Hi Bud and all
Now I am really confused. I have fitted the Europa stall warning mod and sw
itch but not yet used in anger.
How is this switch designed to work?
Is it normally closed and held open by pressure above a certain speed.
Or is it normally open and is closed by low pressure (vacuum), like a conve
ntional Cessna stall warner, caused by the angle of the wing.
The mod leaflet suggests it is operated by vacuum, but your description of
it being on until above a certain speed suggests the first option.
The switch has a hose connection to both sides of what I assume is a diaphr
agm, so it is easy to connect incorrectly.
If it is normally closed then does that result in the buzzer operating cont
inually on the ground until above the stall speed?
I think that would eventually get to be a bit of a pain, especially during
long holds on the ground.
--------
Regards
Kelv Weston
Kit 497
kelv@kdweston.biz<mailto:kelv@kdweston.biz>
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http://forums.matronics.com/viewtopic.php?p=470288#470288
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Message 2
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| Subject: | Re: Cheap chinese landing light |
I use 3480 lumen LED light from Jaycar. See https://www.jaycar.co.uk/3486-lumen-ip68-solid-led-spot-light/p/SL3919. It's as quite as a mouse and cheap too.
Regards
Carl
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470574#470574
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| Subject: | Re: Landing Light Positioning |
The installation looks interesting but raises a few questions about efficiency
of cooling air flow. Is there a moulded cover on the inside? Does it reduce the
cruise speed (a Go-Pro sized camera on mine reduces the cruise by a noticeable
amount).
Did the LAA approve the Mod without any supporting stress calcs?
My scheme does not involve making a sizable hole in the cowling - just a 1/2 dia
hole for the cables, sealed with silicon. The light and moulded support sit
around 2.5in max off the OML.
--------
John Wighton
Europa XS trigear G-IPOD
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470578#470578
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| Subject: | Re: Cheap chinese landing light |
Thanks
Will
On Jun 29, 2017 07:26, "carlp101" <cparkinson@cisc-uk.com> wrote:
>
> I use 3480 lumen LED light from Jaycar. See https://www.jaycar.co.uk/3486-
> lumen-ip68-solid-led-spot-light/p/SL3919. It's as quite as a mouse and
> cheap too.
>
> Regards
> Carl
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=470574#470574
>
>
Message 5
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| Subject: | Re: Landing Light Positioning |
Hi John,
Good questions.
The body of the light is designed as a heat sink and as such has channels through
it for the air to pass through. These are aligned with the flow of air into
the cowl, providing minimal reduction in flow.
I can't say I have noticed a reduction in the cruise speed. I'm burning about 15
liters per hour at 110 kts.
The LAA didn't require any stress calculations as this is not a load bearing part
of the cowl, and the metal bracket helps reinforce the area in any case. The
mod number is 14394.
Regards
Carl
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470583#470583
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| Subject: | Re: Mode S Hexidecimal code |
Hi William,
If you know your octal or binary code from your FAA registration you can covert it to hexadecimal here: http://www.kloth.net/radio/icao24lookup.php
Regards
Carl
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=470588#470588
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| Subject: | Re: Stall Warner - switch problems |
Hi Bud
I think I might have to go with Ian on this one.
The Europa Mod 61 leaflet does state:
Inside the fuselage an adjustable vacuum switch, triggered by reduced pressure
in the line
It also describes connecting the hose to the same side of the switch as the terminals.
Looking at the tech details on the switch, this is side A and should have vacuum
applied to operate the switch.
--------
Regards
Kelv Weston
Kit 497
kelv@kdweston.biz
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