Author: "Scott Chastain" <shophead@...> Time: Fri Aug 19, 2005 11:40 pm PDT Link
Dear Listers:
Electric flaps are standard on the RV-8, and lately, I've been
having a heated discussion with another builder on the use of relays
for the flap motor. Most have told me that relays are not really
necessary, since the switch Van's provides is rated more than
adequately for the application, a typical 7-amp draw in either
direction. However, Bob Nuckolls recommends using relays in
applications going anything over 5 amps to avoid stressing the
switch contacts.
I would like to hear from those of you, on both sides of the fence,
who have a significant number of hours on their aircraft. Do you
think it's a good idea to use a relay system just to protect a
single switch? Personally, I think replacing a switch is a lot less
of a hassle than having relays which, by their mechanical nature,
are eventual failure points. Thanks!
Scott Chastain
N898W Reserved
Wiring
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Author: fiveonepw@... Time: Sat Aug 20, 2005 9:30 am PDT Link
In a message dated 8/20/05 1:40:48 AM Central Daylight Time,
shophead@yahoo.com writes:
> I would like to hear from those of you, on both sides of the fence,
> who have a significant number of hours on their aircraft.
Not sure how significant 220 hours is, but mine's worked well using just a
switch- I do like the less complicated approach, FWIW...
Mark Phillips -6A N51PW Columbia, TN
[Non-text portions of this message have been removed]
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Author: "Larry Bowen" <larry@...> Time: Sat Aug 20, 2005 9:30 am PDT Link
I wasn't aware of Bob's 5 amp limit. I only have one relay in my plane (for
the wig-wag, Bob's design). No problems so far, and I have the fuel pump
and flaps on the smaller switches in the stick. I forget their amp limit.
I hope I didn't just jinx myself. Go for it.
-
Larry Bowen, RV-8 120 Hrs.
Larry@BowenAero.com
http://BowenAero.com
> -----Original Message-----
> From: vansairforce@yahoogroups.com
> [mailto:vansairforce@yahoogroups.com] On Behalf Of Scott Chastain
> Sent: Saturday, August 20, 2005 1:47 AM
> To: vansairforce@yahoogroups.com
> Subject: [VAF Mailing List] Electric Flaps & Relays
>
> Dear Listers:
>
> Electric flaps are standard on the RV-8, and lately, I've
> been having a heated discussion with another builder on the
> use of relays for the flap motor. Most have told me that
> relays are not really necessary, since the switch Van's
> provides is rated more than adequately for the application, a
> typical 7-amp draw in either direction. However, Bob Nuckolls
> recommends using relays in applications going anything over 5
> amps to avoid stressing the switch contacts.
>
> I would like to hear from those of you, on both sides of the
> fence, who have a significant number of hours on their
> aircraft. Do you think it's a good idea to use a relay system
> just to protect a single switch? Personally, I think
> replacing a switch is a lot less of a hassle than having
> relays which, by their mechanical nature, are eventual
> failure points. Thanks!
>
> Scott Chastain
> N898W Reserved
> Wiring
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Author: linn walters <lwalters2@...> Time: Sat Aug 20, 2005 9:31 am PDT Link
This is a little more complicated than meets the eye. You have three
switches (or should have) in your system. The up/down switch and two
limit switches. The startup current for the motor is also greater than
the rating on the tag. The switch system is going to fail down the road
no matter what you do, due to arcing of the contacts if not protected.
HOWEVER, I agree with Bob Nuckolls on the relays to protect the
switches. You don't want to have to take the plane off-line and work on
it while your buddies are winging it for a $200 hamburger (Price of gas
is a killer right now). My flap system will have relays. How much
trouble will it be to replace a limit switch??? BTW, you can get some
really small, high current relays at the auto parts place. Looks like a
cube. Look in the electrical section.
Linn
Scott Chastain wrote:
>Dear Listers:
>
>Electric flaps are standard on the RV-8, and lately, I've been
>having a heated discussion with another builder on the use of relays
>for the flap motor. Most have told me that relays are not really
>necessary, since the switch Van's provides is rated more than
>adequately for the application, a typical 7-amp draw in either
>direction. However, Bob Nuckolls recommends using relays in
>applications going anything over 5 amps to avoid stressing the
>switch contacts.
>
>I would like to hear from those of you, on both sides of the fence,
>who have a significant number of hours on their aircraft. Do you
>think it's a good idea to use a relay system just to protect a
>single switch? Personally, I think replacing a switch is a lot less
>of a hassle than having relays which, by their mechanical nature,
>are eventual failure points. Thanks!
>
>Scott Chastain
>N898W Reserved
>Wiring
>Online help on this group at:
>http://help.yahoo.com/help/groups/
>
>Yahoo! Groups Links
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Author: Phil Birkelbach <phil@...> Time: Sun Aug 21, 2005 5:29 pm PDT Link
If the switch is rated at 7A DC then there is no problem using the
switch. It needs to be a DC rated switch. The only reason to use a
relay is if the switch is not adequate or you would like to have two
different controls for the flaps. My switch is very difficult to
replace and was just barely rated for the current so I used relays.
The motor draws around 3 amps (I measured it) when I was putting as
much load on the mechanism as I could do with armstrong power, so
it'll be less than that just moving the flaps.
Godspeed,
Phil
On Aug 20, 2005, at 0:47, Scott Chastain wrote:
> Dear Listers:
>
> Electric flaps are standard on the RV-8, and lately, I've been
> having a heated discussion with another builder on the use of relays
> for the flap motor. Most have told me that relays are not really
> necessary, since the switch Van's provides is rated more than
> adequately for the application, a typical 7-amp draw in either
> direction. However, Bob Nuckolls recommends using relays in
> applications going anything over 5 amps to avoid stressing the
> switch contacts.
>
> I would like to hear from those of you, on both sides of the fence,
> who have a significant number of hours on their aircraft. Do you
> think it's a good idea to use a relay system just to protect a
> single switch? Personally, I think replacing a switch is a lot less
> of a hassle than having relays which, by their mechanical nature,
> are eventual failure points. Thanks!
>
> Scott Chastain
> N898W Reserved
> Wiring
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