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Flap position indicator

prkaye

Well Known Member
Can anyone recommend an economical solution for a flap position indicator that would be easy to install in a flying RV-9A? At a minimum I would want it to indicate the half-flaps and full-flaps positions.
 
Tape

Get some red vinyl and someone to help you. Set the flaps at 50% and put a strip of vinyl on the left flap even with the trailing edge of the wing. Do the same for 100%. The reason you need a person to help so you can establish your sight lines.
 
Great idea, but im looking for something to provide an in-cockpit indication. As I've been doing my IFR Training it's become apparent to me that this will be useufl (awkward to turn and look at flaps while under the hood).
 
Do you have an EFIS? I connected the rayallen RAC12 flap position sensor to the flap actuator rod and tie the wiring to the Dynon EFIS to display the flap position

Search the word flap sensor so you can see the variety of installation options
 
My plane was built using a Ray Allen POS-12 to send position info to my Advanced Flight EFIS. They do sell a separate position indicator display.

http://www.rayallencompany.com/products/indsens.html


I have been wanting to install a Showplanes Flap Positioning System for awhile...I like the one-touch switch concept so that I don't have to keep holding down the flap switch while extending or retracting. I haven't done that since the flap switch that they include as part of the unit is completely different than the one I have and is ugly. Showplanes tells me I have no other option, I haven't had time/inclination to pursue itfurther.

https://showplanes.com/ecom-prodshow/FPS.html
 
Here's how I installed the POS-12 indicator from Ray Allen.

IMG_2458-M.jpg


Bent up a small strip of aluminum that could be flush riveted to the aft part of the flap housing, then some all-thread rod and an Adel clamp on the flap weldment. You can move the Adel clamp forward or back to get the full 1" of travel for the POS-12. The little attach point in the Adel clamp is made from some aluminum angle with just a bit of the angle left for anti-rotation.
The POS-12 wires go to the VP-X and are displayed on the Dynon Skyview EMS screen. Having the POS-12 input allows you to set intermediate points on the flaps. Mine are set at 10, 20, and 30 degrees with just a momentary push of the flap down button. Flaps go all the way up with a single push of the up button.
 
Thanks Guys! Bruce, your photo was really helpful for me to visualize how this would work. Do you happen to remember what those rod-end bearings are that you used at teh ends of the threaded rod, and how they are pinned to the POS-12 and to the aluminum coupler at the bottom? I think i mgiht want to replicate your design exactly.
 
On my RV-9A, I look out the canopy at the flaps... sometimes. My switch is a preselect in the sense that each successive push gives another "notch" of flaps -- 10°, 20°, 40°. Flaps up is all the way up, no intermediate points.

I always use flaps 10 on takeoff to keep the nose lower on liftoff. Otherwise, on a narrow runway, the runway can disappear from view. Plenty of time to check flaps before getting on the runway.

On instrument approaches, since most of my approaches are to KSAV, with lots of jet traffic, I don't slow down till in close. Then I'll use flaps 10° to keep the nose down when I get to 80 knots. Since I have decided not to fly when the overcast underneath me is less that 1,000 feet AGL, I always break out high and have plenty of time to check flaps if I want to. However, I almost never use flaps 20°, so going to full flaps is all I need -- and that doesn't require looking.

If I encountered an approach to Cat I minimums (200 feet), at RV-9A speeds, there's plenty of time to add full flaps.

What I'm suggesting is that there are instrument approach techniques where flap usage is not critical, so precise flap indication isn't necessary. Works for me, your mileage may vary.
 
A universal fuel sender and gauge combo can be had for less than 30 dollars. Mount the gauge sideways and re label it and link the sender to something in the flap mechanism. A little wiring and figuring out the sender mounting and linkage and you would have a pretty good setup.
 
I'm not familiar and can't give an answer but I'll say this...and it might be worth some food for thought.
I cut my teeth in cessna's and I always thought their flap control solution was elegant.
you can without looking select the next increment and don't have to hold it while the flaps travel
you can glance at it and see the set point
you can fully retract without looking and without holding the switch
it's simple...at least from my view...I have no idea about the mechanism behind the panel

I'll probably try to do something like it if I ever get around to my dream build
...if not an old fashioned johnson bar

I always hated flying those planes that required holding a momentary switch and counting seconds to guess at a flap deflection
 

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Thanks Guys! Bruce, your photo was really helpful for me to visualize how this would work. Do you happen to remember what those rod-end bearings are that you used at teh ends of the threaded rod, and how they are pinned to the POS-12 and to the aluminum coupler at the bottom? I think i mgiht want to replicate your design exactly.

https://www.amazon.com/gp/product/B0006O4HTK/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B00G3OEZGM/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

I forget if I had to upsize the hole in the POS-12, but I think this clevis just fit. On the bottom side, use an adel clamp and a small piece of scrap aluminum and just drill 2 holes in it, one for the adel clamp bolt, and one the right size for the clevis pin. I don't think most people make the aluminum base for the POS-12, I just drilled 2 holes in the vertical piece there and bolted the POS-12 directly to it. It loses some precision, but not enough for me to personally worry about.
 
I'm not familiar and can't give an answer but I'll say this...and it might be worth some food for thought.
I cut my teeth in cessna's and I always thought their flap control solution was elegant.
you can without looking select the next increment and don't have to hold it while the flaps travel
you can glance at it and see the set point
you can fully retract without looking and without holding the switch
it's simple...at least from my view...I have no idea about the mechanism behind the panel

I'll probably try to do something like it if I ever get around to my dream build
...if not an old fashioned johnson bar

I always hated flying those planes that required holding a momentary switch and counting seconds to guess at a flap deflection

Vans - or someone else - sells (or at least, used to sell) something close to this. A momentary push down on the switch (no need to hold), flaps extend to the next set point. Flip the switch up (no need to hold), flaps retract. However, there was nothing indicating current flap position, which is most of what this thread deals with.
For those with a -10 (and two close together flap settings, -3 and 0 (in trail), Bruce’s solution above is easily adapted. Put the Adel clamp for the sensor arm on the actual rotating torque tube, with sensor arm perpendicular to the tube at the 0 deg position. This gives adequate sensitivity to the difference between -3 and 0.
Display on your favorite EFIS.
Note to Ed: I agree, when in good visual conditions, the last 200 vertical feet generally give adequate time to fully extend flaps and re-trim. But I usually advise ifr students not to attempt that without good visual conditions, e.g., 1/2 mile in fog, especially at night.
 
I used the Dubro pushrod and RC servo connectors for the flap position sensor. This device is even less durable than the RC servo so light weight connectors are needed to prevent damaging the sensor unit.
 
On my RV-10 i mounted the Ray Allen position sensor on the outside of the fuse. However, I suspect the following connector hardware I used could also work for an RV-9 flap position set-up.

Ordered from Tower Hobbies:
LXFPW7 Dubro Heavy-Duty Ball Links 4-40 w/Hardware Black
LXFV03 Sullivan Threaded Rod 4-40 12"
LX2812 Associated Flat Head Socket Screw 4-40x9/16"
LXAEPE Associated Socket Head Cap Screw 4-40 x 1-1/4

Hope this helps
 
A momentary push down on the switch (no need to hold), flaps extend to the next set point. Flip the switch up (no need to hold), flaps retract. However, there was nothing indicating current flap position, which is most of what this thread deals with.
I'm intrigued by this. I currently have just a simple toggle that i have to hold down while the flaps lower and retract. For now, I'm using the method of coutning "one Mississippi - two Mississippi - " for partial lowering of flaps without having to turn my head back and look (potentially causing disorientation flying in IMC). If there was a simple drop-in replacemnet for just the switch that would automatically raise and lower the flaps by pre-set amounts, this would be fine - the switch itself could serve as the position indicator. This would be simpler than installing a sensor and indicator. Does anybody know a specific product/part for such a switch that would work as a drop-in replacement for my simple toggle switch?
 
Lots of ways to lick this cat - but I love my Show Planes positioning system.

Does the Showplanes system involve replacing the stock flap actuator? I looked at their installation instructions on their website and I didn't find them totally clear. On Figure 1 i was having a hard time understanding what i was looking at with the way they drew the flap actuator and positioning rod assembly.
Does anybody have close-up photos of this system installed in an RV-6,7,9?
 
I'm intrigued by this. I currently have just a simple toggle that i have to hold down while the flaps lower and retract. For now, I'm using the method of coutning "one Mississippi - two Mississippi - " for partial lowering of flaps without having to turn my head back and look (potentially causing disorientation flying in IMC). If there was a simple drop-in replacemnet for just the switch that would automatically raise and lower the flaps by pre-set amounts, this would be fine - the switch itself could serve as the position indicator. This would be simpler than installing a sensor and indicator. Does anybody know a specific product/part for such a switch that would work as a drop-in replacement for my simple toggle switch?

I'm afraid it isn't that simple, you can't just change the switch. You will need some method of determining WHERE the flaps are, in order to know what the next step would be. The Show Planes system has a switch on the stick or panel that is momentary down and continuous up or neutral. On the flap motor mechanism you install a rod with detents that moves past a microswitch, that is the sensing mechanism that tells the system whether there is more flap travel available up, or down. If the flaps are not fully deployed, then one push down on the momentary switch deploys more flap travel until the next detent is reached and hits the switch - then it stops. If the flaps are at maximum travel, no further extension is available and the system does nothing. There are three notches for flap extension downward, roughly 10, 20 and full. If you flip the switch upward, the flaps will retract fully and the motor will shut off at the top and stay there.

https://showplanes.com/ecom-prodshow/FPS.html
 
I'm intrigued by this. I currently have just a simple toggle that i have to hold down while the flaps lower and retract. For now, I'm using the method of coutning "one Mississippi - two Mississippi - " for partial lowering of flaps without having to turn my head back and look (potentially causing disorientation flying in IMC). If there was a simple drop-in replacemnet for just the switch that would automatically raise and lower the flaps by pre-set amounts, this would be fine - the switch itself could serve as the position indicator. This would be simpler than installing a sensor and indicator. Does anybody know a specific product/part for such a switch that would work as a drop-in replacement for my simple toggle switch?
Again, that appears to be the Showplanes flap positioning system that I referenced and linked earlier, except you can’t tell from the switch position what the state of the flaps is. My EFIS already displays that so I haven’t needed it. Otherwise, the Showplanes FPS is a toggle switch that replaces the current switch. Installation looks pretty straightforward, even retrofitting. My issue is with the cosmetics of the switch design. I’m trying to find alternatives to that particular switch. Currently I use the same Mississippi method of flap deployment as you. That works OK…just looking for something better that might keep me from having to hold the switch down to retract.
 
Does the Showplanes system involve replacing the stock flap actuator? I looked at their installation instructions on their website and I didn't find them totally clear. On Figure 1 i was having a hard time understanding what i was looking at with the way they drew the flap actuator and positioning rod assembly.
Does anybody have close-up photos of this system installed in an RV-6,7,9?

I’ve talked to two different guys at Showplanes and both told me there was no alternative to the switch they supply.
 
I’ve talked to two different guys at Showplanes and both told me there was no alternative to the switch they supply.

Can't imagine why, it's just a switch. I used a Honeywell switch with a flap-shaped lever, which I bought from Steinair.
 
Can't imagine why, it's just a switch. I used a Honeywell switch with a flap-shaped lever, which I bought from Steinair.

Yeah, I don’t know. I was hoping to use my existing Ray Allen rocker switch…momentary up, momentary down, and spring-loaded to neutral/off. What do you think? Is that feasible? Is your switch just a double-pole mom-off-mom?

Otherwise I agree…Stein has a set-screw flap handle that just slips over the bat-handle of the toggle and I’m contemplating. Appears to be highly rated.
 

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Yeah, I don’t know. I was hoping to use my existing Ray Allen rocker switch…momentary up, momentary down, and spring-loaded to neutral. What do you think? Is that feasible?

What's the maximum current rating of your existing switch? Does it carry flap motor current directly or are there relays involved?
 
What's the maximum current rating of your existing switch? Does it carry flap motor current directly or are there relays involved?

I don’t know for sure but I’m inclined to believe there’s no relay involved.
 
What I did on my -4

I have the electric flaps ,aileron trim and elevator trim activated through the MAC stick grip with the 4 trim buttons, and two taller momentary buttons for the flaps. The MAC trim servos have indicator feedback built in, and the flap position uses a MAC trim module connected to the mechanical linkage under the floor via R/C model pushrod. I have 3 indicators in my sub-panel (needle type). They are very accurate, though not really needed when you can visually see the tab and flap positions from the cockpit. Night time and IFR would be different, though I usually just look at mine during run-up scan and take-off settings. The HOTAS set-up is fantastic in the RV, not having to reach and activate a swatch on the panel.
 
I shamelessly ripped off Bruce Hill's installation. Details of all the hardware I used and the approximate dimensions, mounting angles etc. are in my build log. I tried to document that stuff pretty well in the hope that it might help somebody in the future.


Did I say ripped off? I meant "paid tribute to" yeah, thats it, for sure.

edit- I just looked and it's in my build log entry dated Sept 7, 2022
 

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Can't imagine why, it's just a switch. I used a Honeywell switch with a flap-shaped lever, which I bought from Steinair.

The switch itself can certainly be replaced - I'm not using their original switch - but you still need the rest of their hardware. Any momentary "down" and neutral mid/upper 3-position switch will work. I have Tosten grips in my plane and they have a very small switch ideally suited to this application for a stick grip.
 
The switch itself can certainly be replaced - I'm not using their original switch - but you still need the rest of their hardware.

Yes, an important clarification. I ought to have mentioned that I do have all the other Showplanes FPS paraphernalia, but I'm using it with a different switch.
 
I'm also going to pay tribute to Bruce's installation. I'll wire it into one of the general purpose inputs for my Dynon D-180... simple and economical soluton. Thanks guys!
 
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