Van's Air Force
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Flap switch on stick (amps & relays)
- Thread starter justinmg
- Start date
JoeBlank
Well Known Member
Flap Control Board
Check out the following from Vans:
http://www.vansaircraft.com/cgi-bin...66-500-9&browse=electrical&product=flap-board
This should allow you to put the switch in the stick.
Check out the following from Vans:
http://www.vansaircraft.com/cgi-bin...66-500-9&browse=electrical&product=flap-board
This should allow you to put the switch in the stick.
This is really easy to build with an automotive relay - I'm sure someone can post something better then the napkin sketch I have....you probably DO need something other than directly wiring to the switch though.
Paul
Paul
dan
Well Known Member
Rosie's two-relay setup is exactly what I have. Still workin' great after lots and lots of hours & cycles.
When I bought a handful of cheap relays at Radio Smack, I figured...this is an experiment. Wonder how long they'll last. So far so good. 1300 hours and no relay issues (yet?).
From Rosie: I'm at 2600+ hours (thousands of cycles I'm sure) and no problems here...
When I bought a handful of cheap relays at Radio Smack, I figured...this is an experiment. Wonder how long they'll last. So far so good. 1300 hours and no relay issues (yet?).
From Rosie: I'm at 2600+ hours (thousands of cycles I'm sure) and no problems here...
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briand
Well Known Member
How many amps does the actuator draw at approx. full load?
This ? got me thinking:
Anyone know of anyone who tested the load on their flaps in real life flying? If it hasn't been done, I might borrow a strain guage/load cell from work when my plane is done but I bet its been done. You would probably want the results with solo and gross weights and two flaps settings at their respective max extend speeds at least.
This ? got me thinking:
Anyone know of anyone who tested the load on their flaps in real life flying? If it hasn't been done, I might borrow a strain guage/load cell from work when my plane is done but I bet its been done. You would probably want the results with solo and gross weights and two flaps settings at their respective max extend speeds at least.
Steve Sampson
Well Known Member
Relays
If you want to wire up your own you could use relays to be seen at http://211.217.75.113/Promotion/PDF CATEGORY/Relays & Solenoids.pdf go to page 41 and then look for part number 619-760. This is probably a link to the UK catalogue. Farnell is Newark in the USA?
If you are not happy with electrics the VANS part would perhaps be easier.
PS From memory the motor draws a max of around 2 amps but please correct me if someone knows better. I had it fused at 5 and it never blew in my -9a.
If you want to wire up your own you could use relays to be seen at http://211.217.75.113/Promotion/PDF CATEGORY/Relays & Solenoids.pdf go to page 41 and then look for part number 619-760. This is probably a link to the UK catalogue. Farnell is Newark in the USA?
If you are not happy with electrics the VANS part would perhaps be easier.
PS From memory the motor draws a max of around 2 amps but please correct me if someone knows better. I had it fused at 5 and it never blew in my -9a.
dan
Well Known Member
I don't know exactly how much mine draws at full load, but I can tell you the motor drew 800 mA with no load.briand said:
My flaps are wired with 16 AWG and a 10A fuse to protect the wires. Could probably get away with smaller (lighter) wire & fuse, but I wasn't sure what the loaded current consumption would be.
Thanks all.
I suspect I will go for the Vans part if it is straight forward.
BUT.....where does the part go?
Near the flaps or current panel switch?
Can I retain the panel switch with this?
To my interpretation, Rosies otherwise elegant solution (switching ground) would not allow the old switch (switching 12v) be be retained.
I suspect I will go for the Vans part if it is straight forward.
BUT.....where does the part go?
Near the flaps or current panel switch?
Can I retain the panel switch with this?
To my interpretation, Rosies otherwise elegant solution (switching ground) would not allow the old switch (switching 12v) be be retained.
Quick question -Rosie said:Please forgive the crude drawing but I used MS_Paint (and drawn from about a 9 year memory in my head...)
Here is what I have on my control stick that runs only a ground through the stick to the momentary switch.
Click the picture to enlargeRosie
Why did you choose to keep both sides of the motor at 12v and switch the ground vs. keeping the motor at ground potential and switching 12v?
With the relays/motor wired as they are if one wire leading from the com->motor or coil->switch becomes chafed and grounds out the motor will run or pop the breaker (depends on the fault).
I'm a controls engineer by trade so I look at relay/motor circuits for possible faults that could potentially lead to a safety issue. I'm not trying to criticize as obviously it hasn't been a problem for your or Dan, but I'm just curious why it was done this way to begin with.
I would feel better with it wired like this:
The worst that would happen if a wire grounds out with it configured this way would be a popped breaker.
Now, the possibility of the wire becoming chafed in flight is pretty remote as long as it is properly secured, but it sure would be surprising to have the flaps extend in cruise when you least expect it...
Discuss please, if my interpretation is wrong or if this is a best practice thing I'd like to know.
Mark Burns
Well Known Member
I'd like to know also
Tyson,
I see this 'switching the ground" quite often in aircraft wiring. I've asked an engineer who designs aircraft circuits and frequents this site and he didn't have a good answer either!
It is possible to save a wire run here and there by switching the grounds.
It depends on how far away each device is from each other to determine if it makes sense.
I design industrial control circuits myself, and switching the ground is seldom used in the industrial world. To me it just makes it harder to keep it straight in your head whats happening. And there's no need to make it hard on the guys trying to troubleshoot the machine buy doing something odd to save a wire or two.
Mark
tysonb said:Quick question -
Why did you choose to keep both sides of the motor at 12v and switch the ground vs. keeping the motor at ground potential and switching 12v?
With the relays/motor wired as they are if one wire leading from the com->motor or coil->switch becomes chafed and grounds out the motor will run or pop the breaker (depends on the fault).
I'm a controls engineer by trade so I look at relay/motor circuits for possible faults that could potentially lead to a safety issue. I'm not trying to criticize as obviously it hasn't been a problem for your or Dan, but I'm just curious why it was done this way to begin with.
I would feel better with it wired like this:
The worst that would happen if a wire grounds out with it configured this way would be a popped breaker.
Now, the possibility of the wire becoming chafed in flight is pretty remote as long as it is properly secured, but it sure would be surprising to have the flaps extend in cruise when you least expect it...
Discuss please, if my interpretation is wrong or if this is a best practice thing I'd like to know.
Tyson,
I see this 'switching the ground" quite often in aircraft wiring. I've asked an engineer who designs aircraft circuits and frequents this site and he didn't have a good answer either!
It is possible to save a wire run here and there by switching the grounds.
It depends on how far away each device is from each other to determine if it makes sense.
I design industrial control circuits myself, and switching the ground is seldom used in the industrial world. To me it just makes it harder to keep it straight in your head whats happening. And there's no need to make it hard on the guys trying to troubleshoot the machine buy doing something odd to save a wire or two.
Mark
DaX
Well Known Member
Mark Burns said:
Switching the ground is common in automobile wiring to the ECU as well. The way it was explained to me is that if a wire from an output device (input into the ECU) gets shorted to ground, it will not harm the ECU since it is a ground to begin with. Since this is the safest way to wire devices that tell the ECU something, it is natural to continue this method of wiring to components that are told what to do by the ECU. Hope that semi-explains it.
JonathanCook
Well Known Member
Try using Bosch style automotive relays
I once said that I would never use automotive products on "my" airplane. I bet a lot of other builders have said thoes same words also. Well, after looking for relays for my flaps I am going to use Bosch or Bosch style relays. First, I do not see them being less robust than aircraft relays, which I have already. And if the flap circuit failed, I would still be able to fly the RV7 with flaps up, down, or somewhere in between. If a Bosch relay fails, it can be replaced almost anywhere. But the features that I like the most is that I can secure the relay easily because the relay has a mounting hole and I can use 1/4" AMP fast-ons to connect the relay. I have aircraft relays from Deutsch Relay, but I need to solder the contacts, or puchase the relay connector kit. When you purchase the Bosch Relays you have to get single pole double throw (spdt). DPDT would also work, but it is not necessary.
I once said that I would never use automotive products on "my" airplane. I bet a lot of other builders have said thoes same words also. Well, after looking for relays for my flaps I am going to use Bosch or Bosch style relays. First, I do not see them being less robust than aircraft relays, which I have already. And if the flap circuit failed, I would still be able to fly the RV7 with flaps up, down, or somewhere in between. If a Bosch relay fails, it can be replaced almost anywhere. But the features that I like the most is that I can secure the relay easily because the relay has a mounting hole and I can use 1/4" AMP fast-ons to connect the relay. I have aircraft relays from Deutsch Relay, but I need to solder the contacts, or puchase the relay connector kit. When you purchase the Bosch Relays you have to get single pole double throw (spdt). DPDT would also work, but it is not necessary.
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I am assuming you want the reliability of Van's direct switch
as a backup and the stick grip for normal use. If the panel
switch was used to activate the relays it will be easy, if not
it would need different relays, more relays and/or a different
direct switch.
The diagrams shown use 12+ as control wiring and as the NC
circuit. I prefer to use grounds on both and have no problem
visualising this type of circuit. The biggest reason for this is
that the high amp controlled circuit could be run with only one
fuse and smaller amp control circuits could be run with thin
gauge wire appropriate to the control circuit current draw. If
there is a 10 gauge fuse on the flap circuit with 16 gauge wire
the 24 gauge stick grip wire would be unprotected from a short
requiring either another smaller fuse or fuse link to protect it.
I have no 12+ circuits to the grip.
George Meketa
RV8 800+hours
as a backup and the stick grip for normal use. If the panel
switch was used to activate the relays it will be easy, if not
it would need different relays, more relays and/or a different
direct switch.
The diagrams shown use 12+ as control wiring and as the NC
circuit. I prefer to use grounds on both and have no problem
visualising this type of circuit. The biggest reason for this is
that the high amp controlled circuit could be run with only one
fuse and smaller amp control circuits could be run with thin
gauge wire appropriate to the control circuit current draw. If
there is a 10 gauge fuse on the flap circuit with 16 gauge wire
the 24 gauge stick grip wire would be unprotected from a short
requiring either another smaller fuse or fuse link to protect it.
I have no 12+ circuits to the grip.
George Meketa
RV8 800+hours
jdeas
Well Known Member
Switching to Gnd
Switching to ground is also popular because it allowed you to replace or augment the switch with an open collect NPN transistor. Using a simple OC NPN you could switch large loads with a minimum of support circutry or power loss (heat). There are many IC chips that have these NPN structures in the 1-5 amp range. PNP transistors could be used in the same way for the positive rail but are more expensive for the same size and generally create more heat.
Switching to ground is also popular because it allowed you to replace or augment the switch with an open collect NPN transistor. Using a simple OC NPN you could switch large loads with a minimum of support circutry or power loss (heat). There are many IC chips that have these NPN structures in the 1-5 amp range. PNP transistors could be used in the same way for the positive rail but are more expensive for the same size and generally create more heat.
Short time-out to wave the "simple is better" flag <g>
Relays and wiring not installed never become a failure.
Nothing wrong with a sensible want. Why do you need flaps wired to a grip switch?
Side issue; inadvertent extension becomes very unlikely with a panel toggle. There are times when it could kill you.
Relays and wiring not installed never become a failure.
Nothing wrong with a sensible want. Why do you need flaps wired to a grip switch?
Side issue; inadvertent extension becomes very unlikely with a panel toggle. There are times when it could kill you.
f1rocket
Well Known Member
I actually have the flaps wired to my stick using Van's flap board, but I wish I had the switch on my throttle. That way I could lower the flaps with my left hand and bump the trim switches with my right hand on the stick. Having both flaps and trim on the stick make that difficult.
Just something else to think about.
Just something else to think about.
Rick6a
Well Known Member
I'd be curious to know exactly how many RV's have been lost to or experienced inadvertant flap deployment with the flaps rigged to a momentary toggle switch. The reality is with such an arrangement, you have to physically depress the toggle for several seconds to fully cycle the flaps one way or the other. To do it "inadvertently" is like trying to beat a freight train to the RR crossing in your auto and hitting the 26th car!DanH said:
Recently, I gave my neighbor his very first RV ride. He's an ex-naval aviator (E-2 Hawkeyes) and is an active, veteran airline pilot. He marveled at the handling and performance my 6A offered at altitudes less than 3000'..... an experience and perspective he hasn't known for many years. He admitted that flight level flying is a routine and heavily disciplined career path. Long story short.....as I proceeded through the traffic pattern he asked quizzically...."You don't lower the flaps for landing?" I replied, "They are lowered Bob. I've got them rigged to the grip. That way, I don't have to reach for a switch." "Great idea," he said as he immediately turned his head to visually confirm the deployed flaps.......
Until I built an RV to please me the builder, I never flew an airplane that reflected exactly what I was looking for in pilot ergonomics. With an Infinity grip installed, I chose a momentary toggle for flaps, 2 axis electric trim controlled by China hat, and PTT on the trigger. I am completely satisfied with the arrangement. In the traffic pattern, my left hand has no need to leave the grip to deploy flaps, trim for slow flight, and communicate on CTAF. For me personally, I can't imagine a better arrangement. I am so satified with the setup that the -8 will be rigged exactly the same way. A major satisfaction the builder will always feel is that the airplane he builds and flies is a highly personal expression of an individual's craft.....NOT the culmination of somebody else's perspective, bias, preference, or dogma.
<<That way, I don't have to reach for a switch>>
Oh.
<<The reality is with such an arrangement, you have to physically depress the toggle for several seconds to fully cycle the flaps one way or the other.>>
As one poster already noted, the popular wiring arrangement (grounding through a grip switch) has the potential for runaway merely by chafing a wire in the long stick run, no dumb pilot tricks required. Can you realize your flaps are extending, then find and pull the correct breaker in less than "several seconds"?
Yes, the risk is small, but that misses the point. It is not as small as zero, which is what you have when the unnecessary bits are not added to the system. Adding more and more "features" is the classic homebuilders disease.
Oh.
<<The reality is with such an arrangement, you have to physically depress the toggle for several seconds to fully cycle the flaps one way or the other.>>
As one poster already noted, the popular wiring arrangement (grounding through a grip switch) has the potential for runaway merely by chafing a wire in the long stick run, no dumb pilot tricks required. Can you realize your flaps are extending, then find and pull the correct breaker in less than "several seconds"?
Yes, the risk is small, but that misses the point. It is not as small as zero, which is what you have when the unnecessary bits are not added to the system. Adding more and more "features" is the classic homebuilders disease.
Gsuit said:
No pics or schematic, just a whole system that includes flaps and trim. With the recent Cessna crash highlighting the importance of safe systems, here's something to consider. The Vertical Power system shows on the pilot display when either trim or flaps is running, and will have audio tones as well. There are no mechanical relays - each flap and trim control circuit uses two solid state switches in series, so that if one fails you don't have a runaway condition. We also stop the motor if opposite trim or flap is commanded - so if the down trim wire shorts for example, you press the up trim button and the motor stops. Hold this for 3 seconds and the trim switch is disconnected. You can then run the trim & flaps from the display (using the soft keys) as a backup and hopefully get the trim back to neutral.
Runaway trim is a very bad condition, and we wanted to design a system that makes electric trim safe yet easy to wire. It would be a huge mess to wire this as a discrete system with relays, etc. but as part of an engineered system, it's actually very simple to install and setup. Come by and take a look at OSH.
