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Flap Travel

bkervaski

Hellloooooooo!
Testing
Hi All,

I read on a -10 post that the reflex position (-3 degrees) is when the flap is lined up with the bottom of the fuselage, is that true for the 14?

I've tried following the book and using the 7 degree offset to get the starting point, could never get less than 8 degrees before the flaps would bottom out on the spar. Called Vans, they said "that's fine, that's your starting point."

What are you guys using for your flap positions between -3 and 30?

Are you getting 30 or more?

If so, how much did you adjust your push rod from the plans?

Any insight into others' setup procedure here would be very much appreciated!

And finally ... All of my flap hinges are rubbing on one side or the other towards the top (quick build wings), is paint rubbing off here a normal accepted thing with an RV? (no frame of reference so not sure)
 
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I would be interested in what others had to say.

I remember building my seven, I lined my flaps up with the neutral position of my ailerons. I do not think I used any other means.
But it is possible, I could be absent minded, so I will listen for the right answer.
Dave
 
Bill,

I'm way behind your stage in the build and haven't mounted my wings to the fuselage yet, but on the wing stand I get approx 3 deg reflex when the flaps make contact with the rear spar. Dunno if that aligns exactly with the bottom of the fuselage, but I agree with Vans, that's your starting point...full up position. As long as the full down position is plus or minus a few deg from what Vans specs (30 I believe?) you'll be fine...full flap deflection angle isn't critical, but one thing I'd recommend checking is that both flaps are at the SAME angle especially in the full up position. If not, you're going to be out of rig. Same for the ailerons in the neutral position, they should measure the same angle with your digital level.

Regarding the flap hinges rubbing, have you checked to verify that the hinge bushing is exactly centered? You could also move the bushing slightly off-center if that helps with overall alignment. On my wings (in the wing stand) there's no contact anywhere. If you can't tweak things to avoid contact in all positions, you could use some clear 3M paint protection tape on the affected areas after painting. I also plan to put some tape on the top surface of the flap where it contacts the upper skin, and on the leading edge where it makes contact with the rear spar in the fully retracted (3 deg reflex) position.
 
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Which section of the plan covers the flap final installation? I have gone thru the Wing section and did not see any specifics for the flap beside the construction of it.
I bought the thumb drive but have found that I am missing many of the parts.
 
Regarding the flap hinges rubbing, have you checked to verify that the hinge bushing is exactly centered?

Yep, even offset them a bit to relieve the clearance a bit, but still not getting enough gap to where paint will stay on over time, rubbing.

I also shimmed the bolt to see if that would help but it didn't affect the top part were the rubbing is.

It looks like the flaps internal ribs' flange radius is the culprit, causing the hinge to be ever so slightly narrower towards the top. Quick build flaps.
 
Hi All,

I read on a -10 post that the reflex position (-3 degrees) is when the flap is lined up with the bottom of the fuselage, is that true for the 14?

I've tried following the book and using the 7 degree offset to get the starting point, could never get less than 8 degrees before the flaps would bottom out on the spar. Called Vans, they said "that's fine, that's your starting point."

What are you guys using for your flap positions between -3 and 30?

Are you getting 30 or more?

If so, how much did you adjust your push rod from the plans?

Any insight into others' setup procedure here would be very much appreciated!

And finally ... All of my flap hinges are rubbing on one side or the other towards the top (quick build wings), is paint rubbing off here a normal accepted thing with an RV? (no frame of reference so not sure)

I have a RV-10, so I can't specifically answer your question. But I would think if you set a level on the wing and aligned the flap with the level, that would be 0. Using a digital level it would be easy to make the other measurements.

Again, on my RV-10, I have -3, 0, 15, 30 or something close. I don't remember the exact travel of the top of my head. It's basically -3,0, half, and full flaps.

Rubbing is a bad thing! You need to resolve that issue by making a mechanical adjustment or filing the offending piece so it clears. Without see your specific issue, I would be hesitant to make a specific recommendation.
 
Rubbing is a bad thing! You need to resolve that issue by making a mechanical adjustment or filing the offending piece so it clears.

Unfortunately, there is no adjustment to the top of the hinge, it's embedded inside the quick build flap between two ribs.

I'm going to try to adjust the bushings again this morning then call Vans, sounds like rubbing here isn't normal.
 
My hinge does not rub at all. The skin does rub where the flap meets the top skin when the aileron is fully up. It's a feature now because my flaps are being stored on top of the wing in the wing stand and it keeps the flap from moving around. But I think I will have to do a bit of work with the seamer to life that skin up some off the flap before I mount it for real.
 
My hinge does not rub at all. The skin does rub where the flap meets the top skin when the aileron is fully up. It's a feature now because my flaps are being stored on top of the wing in the wing stand and it keeps the flap from moving around. But I think I will have to do a bit of work with the seamer to life that skin up some off the flap before I mount it for real.

We had a local builder fabricate a tool for just such a purpose. It came in handy on my RV-10. You could tweak the entire trailing edge at once.

He was an engineer that never found a problem he couldn't build a tool to fix. Unfortunately, he's moved out of state and I've lost contact with him.
 
Unfortunately, there is no adjustment to the top of the hinge, it's embedded inside the quick build flap between two ribs.

I'm going to try to adjust the bushings again this morning then call Vans, sounds like rubbing here isn't normal.
Bill,
Please let us know what VANS suggest about this. Mine rubs on one side (inboard side both side) so if I could shift the whole thing about .015, then probably wouldn't rob and it is only the last 3 or 4 degrees that starts rubbing.

I also checked the reflex degree which is about 4.2 degree if I set my reference point to the top of the wing and measure it when the flap hits the rear spar.

Hope this gives you more data point.
 
Bill,
I was able to adjust the hinge on the Flap enough to stop it from rubbing. I took a piece of .25" aluminum bar (roughly 8" long) and inserted in at the root of the hinge nearest to the flap where it was rubbing. It was clear that the gap in the hinge was lets than .25 as would not easily slid in-out. I used this bar to pry it open ever so slightly (about .010-.015") just enough that it could slide in and out with little to no resistance and now I am not rubbing any more. The gap is still not enough that I could say for sure it would not rub once painted but at least now it is retracting fully without rubbing.

Hope this will work for you as well.
 
I was able to adjust the hinge on the Flap enough to stop it from rubbing. I took a piece of .25" aluminum bar (roughly 8" long) and inserted in at the root of the hinge nearest to the flap where it was rubbing. It was clear that the gap in the hinge was lets than .25 as would not easily slid in-out. I used this bar to pry it open ever so slightly (about .010-.015") just enough that it could slide in and out with little to no resistance and now I am not rubbing any more. The gap is still not enough that I could say for sure it would not rub once painted but at least now it is retracting fully without rubbing.

I did a bit of that and a little filing and got it all to fit smoothly without interference, like you, not sure if it's going to be enough to keep the paint on. I may just draw a line and have them not paint the travel area.

Flaps .. DONE!

Oh, and don't try to use -3 on the G3X to set a flap position .. it doesn't like that negative number and will go to manual mode every time. I just set 0, 10, 20, 30 and everything works great (0 being my reflex position).

Also .. for what it's worth to those of you who haven't got to this point yet .. the flap motor that Vans provides continues to run for just a split second after the it's turned off so you have to set your flap position sensor voltages high for 0 degrees and low for 30 degrees so the flaps fall into place. The incremental positions set as close as you can, they will never be perfectly on target. If the motor is running up the 20 degree stop point might end up being 19 degrees and if the motor is running down it may end up 21, etc. I tried to make this perfect until I realized that you would never notice such a small difference in flight.
 
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Oh, and don't try to use -3 on the G3X to set a flap position .. it doesn't like that negative number and will go to manual mode every time. I just set 0, 10, 20, 30 and everything works great (0 being my reflex position).

-3? no problem on my G3x touch. I use -3, 0, 15, 30. Are you using a G3x or G3x touch?

flapscale.pdf
 
-3? no problem on my G3x touch. I use -3, 0, 15, 30. Are you using a G3x or G3x touch?

G3x Touch 4xx version 5.9 (latest as of this post) and Ray Allen POS-12 flap position sensor.

Even Garmin was stumped.

I'd love to know what your -3 and 0 voltages are set to in the calibration.

Also, and this is a question based on being a fairly new pilot, what benifit would having -3 and 0 available and why would you ever need a 0 position in flight? With such a small change, what's the benefit of having those two positions so close together available? Seems that in flight, having them so close together, you would end up choosing the wrong one all the time.
 
I can check the values next time I'm at the airport. Same hardware and software setup as you.

I use 0 for takeoff only. I raise to -3 and shutoff the aux fuel pump at about 500 feet in the climb.
 
When I was flying the fourteen I used three settings. All the way up, all the way down and half way down for take off and base to final turn.
When you can see three screws on the aileron the flaps are about half way down.
The flap speed is slow, I counted, in my head, to 15, and that was very close to the half flap setting of three screws visible on the end of the aileron.
Not really any need to consider the reflex position.
 
When I was flying the fourteen I used three settings. All the way up, all the way down and half way down for take off and base to final turn.
When you can see three screws on the aileron the flaps are about half way down.
The flap speed is slow, I counted, in my head, to 15, and that was very close to the half flap setting of three screws visible on the end of the aileron.
Not really any need to consider the reflex position.

My understanding is that "all the way up" IS the reflex position - this aligns with ailerons when they align with wingtips: the "reflex" is built into the shape of the wing. Not sure what the "zero" position is used for yet - guess I'll figure it out when I start flying...
 
The RV-14 (and RV-10) have a custom designed airfoil meant to reduce induced drag in level flight at high speed cruise. The ailerons are rigged to match the desired reflex shape of the airfoil but since the flaps are movable, they can be moved out of the reflex position. This essentially makes the wing act like it has a bit more wing area, improving climb performance slightly.

The way we fly our RV-10's and 14's is to take-off with whatever flap setting you choose (1/2 or zero), and then position them to zero for climb.
Then position them to -3 as you level off and set cruise power.
After decent and leveling off to enter the pattern, return them to zero and then use flaps as desired (within the limitations of Vfe)
In simpler terms - reflex position for cruise and decent - zero for everything else.

We have G3X (with GAD27 module) in our RV-10 and had no problem setting up the indicator for -3, 0, 15, and 30 degrees.
 
Scott's description is what Mike Seager taught me.

I now only use 0? for takeoff and initial climb because I was consistently forgetting to raise them in cruise despite my cruise checklist. I may switch back now that I have considerably more hours in the plane.
 
Scott's description is what Mike Seager taught me.

I now only use 0? for takeoff and initial climb because I was consistently forgetting to raise them in cruise despite my cruise checklist. I may switch back now that I have considerably more hours in the plane.

What are the relative advantages / disadvantages (other than forgetting to raise flaps) of using take-off flaps more than "zero"? I fly from mostly paved runways over 3K feet so takeoff distance not a major concern.
 
Scott, I never did test the difference between the "0" setting and the -3 or reflex setting. I can understand how it would climb a bit better in the "0" but what is the actual climb difference in feet per minute?
The climb is so good in the reflex position, even at gross weight that I wonder it is worth the bother. There is also the opportunity to forget to go to reflux at cruise, not that I ever forget to flip a switch....
 
Scott, I never did test the difference between the "0" setting and the -3 or reflex setting. I can understand how it would climb a bit better in the "0" but what is the actual climb difference in feet per minute?
The climb is so good in the reflex position, even at gross weight that I wonder it is worth the bother. There is also the opportunity to forget to go to reflux at cruise, not that I ever forget to flip a switch....

I can't remember the amount of difference testing showed.
Perhaps Steve (airfoil designer and RV-8 owner here on VAF) would comment on what the theoretical difference is.
 
I have actually wondered about the opposite question: Is there a density altitude, above which true airspeed is higher with zero deg flaps? I did some experimenting around 16,000 DA (iirc) and couldn?t detect any difference. But it wasn?t perfectly smooth at the time.

A scond question for Scott: my 2009 rv10 kit came with a max speed limitation for zero flaps. Has that been removed from newer kits? Do I need any upgraded parts to remove the limitation?
 
my 2009 rv10 kit came with a max speed limitation for zero flaps. Has that been removed from newer kits? Do I need any upgraded parts to remove the limitation?

Nothing has changed

That is why in my description of how we operate the airplanes I mentioned that we climb at the zero flap setting, cruise and descend at the -3 setting, and then revert back to zero when slowing for pattern entry.
 
My understanding (and I could be completely wrong), is that reflex helps take some load and trim off the tail, particularly with lighter loading = forward CG. With higher and aft loading, it is less beneficial. In certain circumstances, I have seen a 3 knot improvement at cruise going from trail to reflex position on flaps. In other circumstances, I?ve seen negligible effect.

Like others have posted, I use trail for takeoff and climb, and during maneuvers such as instrument approaches - otherwise reflex.
 
@n982sx Thank you! It appears your voltages are scaled opposite mine. I looked online at some other screenshots of the calibration screen and they line up with yours. So, it appears, I may have two wires swapped on the POS-12.
 
My understanding (and I could be completely wrong), is that reflex helps take some load and trim off the tail, particularly with lighter loading = forward CG.

No.
It is like I already said, its specific to the airfoil design and a reduction in induced drag.

Otherwise it would be beneficial to all the RV's, regardless of what model.
 
@n982sx Thank you! It appears your voltages are scaled opposite mine.

I should have mentioned that I swapped the wires from the sensor to reverse the slope of the voltage line. I also had to swap the the GAD 27 flap wire control wires.

The GAD 27 software seems to think that the signal voltage will always drop as the flaps come down. This is not true with the installation of the POS 12 per Vans RV 14 installation. This is really a software problem fixed via hardware. Nothing wrong with the Van's installation or the POS 12.
 
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