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Flap Position Sensor Mounting

Mike S

Mike S

Senior Curmudgeon
I have received a couple of requests for info on how I mounted the Ray Allen POS 12 for sensing the flap position.

Figured it might be of interest to others.

The bracket was mocked up in cardboard from a cereal box to get the right size/shape, and then mounted with pop rivets. It is mounted level with the ball on the flap horn, when the flaps are at mid travel. I used .032" or .040" scrap stock, be sure to drill a hole--1/4" works fine, in the corner where the mounting tabs will be bent away from, you will end up with a nice inside corner radius after bending the tabs. Last photo shows this well.

The linkage is from the Radio Control aircraft world, I used a couple of 4-40 size ball links, and pushrod stock, and a solder on threaded adapter. The small aluminum plate is riveted on to the flap control horn so the ball link is in the middle of the lightening hole in the bracket. Use locktite, or peen the threads on the ball link-------access to re tighten a loose nut is not good.

I made up the same for a buddy; it has been working fine on his 10 for a couple of years now.

Electrical connections are D-sub pins, with heat shrink tubing.

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Good Luck,
 
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Yes, Ray Allen POS 12.

I am using the Ray Allen display light bar units, but my friends 10 is feeding into the AFS efis---works fine.
 
Mike,
I hadn't thought about putting it on the outside. Did mine on the yoke attached to the motor in the tunnel. Same principle, though. I did find a slick way to mount something through the lightening hole. Go to Ace Hardware (aviation section of course) and look for something in the pull out drawers called an "expansion nut" or a "well nut." It looks like a big rubber Rivnut. It takes a 1/4" screw (I used a nylon one to keep the weight down). The expansion nut works just like a Rivnut but you don't have to use it that way. I put the screw in from the other direction with a washer so it holds it in tight between the yoke's two flanges. It gives you a solid mount through that big 1/2" lightening hole.
As far as mounting the Ray Allen POS 12 position sensor, I'm using double-sided carpet tape on the tunnel wall. The 4-40 model airplane clevis', ball links, etc., work great.
John
 
Hey Mike,

I'm pulling up an oldie but goodie here.

How did you determine what full travel was on the worm gear? My wings/flaps are not attached, so I can't tell how far the worm gear has to travel to bring the flaps to the reflex position and then again at full-down.

Am I correct is assuming the full length (extreme limits) of the worm gear will be used?

Phil
 
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Phil, as far as I know, the unit uses the full travel.

I have the ShowPlanes flap positioning system, so I just set the travel up to the preset locations in it.
 
Hmmm.. I've got some work to do then.

I own the showplanes unit, but I'm not going to use it. I'm going with the Aircraft Extras unit.

http://www.aircraftextras.com/FPS-PlusReflex.htm

Now the question is how to determine full reflex and full down without the flaps on and using a different unit.

I really think the SP unit is terrible, but I might install it long enough to determine full down and full reflex, then yank it back out of the airplane.

I'll have to read the G3X manual. There might be a software setting to set the upper and lower limits for their flap position indicator, then it extrapolates the flap position setting from that data. (In other words, it may not need to be 100% perfect travel.)

Phil
 
Phil, you set the reflex to the rear spar-----the flap LE bumps the spar. Then you adjust the length of the flap push rod to make the connection at the end of the flap torque tube at full reflex position.

Biggest problem I had getting this adjustment was filing the end of the flap to allow the clearance to the fuse.
 
That makes a little sense to me.. I'll take a look at the rigging chapter and see if I can't put all the pieces together.

I did check the G3X installation documents and they have a calibration routine built-in. (I'm using the G3X for my indicators and not the Ray Allen Indicators)

That means I don't have to have perfect travel on the sensor from reflex to full-down. I can position the flaps in reflex and essentially tell the G3X to memorize that position (AKA: Voltage coming out of the flap position sensor). I can have up to 8 positions memorized.

The same is true for the FPS-Plus from Aircraft Extras. I position the flaps and then tell it to remember the voltage coming out of the sensor as a position. Of course I'll have to run two sensors in the airframe - one for the G3X and one for the flap controller.

But it looks like I don't have to be perfect. I'm going to set the sensor for full travel of the worm gear and then memorize the voltage stops in-between.

Thanks for guiding my thought process through it.

Phil
(Cutting the cabin top a little every evening until it fits)
 
Resurrecting old thread

Mike S said:
Phil, you set the reflex to the rear spar-----the flap LE bumps the spar. Then you adjust the length of the flap push rod to make the connection at the end of the flap torque tube at full reflex position.

Biggest problem I had getting this adjustment was filing the end of the flap to allow the clearance to the fuse.
Click to expand...

As someone who just spent hours closing up the ends of his flaps (and ailerons, rudder and elevators) with foam and glass, this phrase sends chills down my spine. Not sure I like the sound of this "filing" you speak of. Is it always necessary?
 
Bill, I have no idea if it is always needed, but I had to do it.

Been a lot of years now, but I seem to remember the instructions may have indicated the need?
 
Bill Boyd said:
As someone who just spent hours closing up the ends of his flaps (and ailerons, rudder and elevators) with foam and glass, this phrase sends chills down my spine. Not sure I like the sound of this "filing" you speak of. Is it always necessary?
Click to expand...

I think it ends ends up being almost always necessary. You will want the clearance to the bare metal fuselage side to be enough not to scrape the paint off, so make the gap at least twice the expected paint thickness and then some for clearance.
 
Well,

<expletive> :mad:

Didn't read ahead to that detail, so I'll be hogging out some beautifully applied fiberglass closures to gain this clearance, no doubt.

What I get for assuming a kit with holes punched and skins trimmed to the thousandths is engineered this way everywhere, instead of just mostly everywhere. Part of the 51% :cool:

In retrospect, there may not have been any drag reduction to be had by closing off the inboard flap ribs, since there is little opportunity for air flow past them in the cruise position - but I'm speculating that without benefit of a finished/flying RV-10 to look at.
 
Bill Boyd said:
<expletive> :mad:

Didn't read ahead to that detail, so I'll be hogging out some beautifully applied fiberglass closures to gain this clearance, no doubt. SNIP
.
Click to expand...

I too glass in all rib ends. There is no drag or other gain in doing this, just pure aesthetics. As you point out, no need to do the inboard flap ribs.

Note - make sure you have a 1/4? or so drain hole at the trailing edge of each sealed rib.

Carl
 
Drag reduction

I went ahead with this effort because a long time ago I got a recommendation from Rick Gray to do so on my 6A for some added speed (never got around to doing it, though. Rick did his, and believed there was benefit).

Intuitively (which doesn't always work in aerodynamics), one looks at those hollowed control surface end ribs and thinks "there's got to be a lot of eddy currents swirling in there creating drag." Are we sure there's no drag reduction in smoothing them out with a closure panel? I'm not.

IMO, the cosmetics alone are in no way worth the effort to close them up - so if there's no drag reduction payoff, I just wasted a lot of effort on, of all things, more fiberglass work on a metal airplane :(
 
Drag

As was previously posted, filling those areas is predominantly for aesthetics. Though there may be a minuscule drag decrease, it will likely be imperceptible.

That being said, someone who is interested in reducing drag to a bare minimum, regardless of the cost, will counter that even a minuscule reduction is worth it because all of the reductions add up...which is true.

I would be more inclined to add Jesse's wing fillet fairing over glassing the ends of the flaps. You are likely to see that drag reduction in your performance...and they look really cool!:D
 
I'm all about me some Jesse Saint

and so glad we have peerless resources like him in the RV-10 world.

His intersection fairings are not without controversy from what I've read here on VAF (as far as drag reduction, not aesthetics). I built a set of curved fillet fairings for my 6A 20 years ago, probably needlessly heavy for what they are, but admittedly nice looking, compliment-collectors. My plane has never flown without them. I'm not sure they make my plane one bit faster; I have one of the slower 160hp FP 6A's out there but have done no experimentation to see what may be factoring in to that (i.e. flying with factory gap seals, etc.)

When it comes to those fairings, I want to believe... but I'd prefer to see data - good, side-by-side data.

... which I'd also like to see for enclosing the ends of the control surfaces, and for rod antennas - the kind of before and after testing that Melton is doing for his 3D printed fairings.
 
Jesse, how much are those "really nice wing fillet fairings?" When is the best time to get them on sale?
 
jeffwhip said:
Jesse, how much are those "really nice wing fillet fairings?" When is the best time to get them on sale?
Click to expand...

They are $2,000 with "basic" installation included, or crated to ship. There are more various ways to install them, so we included the basic installation, but more complex installation would be extra. I can share details off-line.

I our testing and independent testing, the average is 3-4 knots increase in cruise speed, with 5 knots claimed on one installation. The stall speed also decreased by 2-3 knots in our in-house, though not extremely scientific, testing.
 
I wish

I wish I still had access to the fluid dynamics programs I used in college. It would be a fairly simple task to model that intersection and get some numbers...

Really not necessary though cause they look cool!
 
Definitely keeping this option open for later

The performance numbers Jesse is throwing out are the kind that seriously tempt me to make another set, after swearing off such behavior 20 years ago. After all, I must know so much more about fiberglass work now than I did then... :D

I mostly remember the endless hours of contour sanding with a cylindrical sanding block to get the outer surface smooth after making the layup over a male foam-in-place mold. Not sure I knew anything about peel-ply or micro back then, nor Dan's nappy roller sanding guide-coat tricks. Even so, this is a formidable undertaking.
 
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