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Flap actuator minimum and maximum extension

iamtheari

Well Known Member
So, I did a smart thing and ordered the PH Aviation flap motor with built-in position sensor. But then I did a dumb thing and sent my flap motor back to Van's without first checking the minimum and maximum extension of it to be able to compensate for the differences in the replacement part.

The PH Aviation instructions say "the PHA actuator is not a drop-in replacement for the stock RV actuator. it is actually about 1.5" longer and a little taller." They go on to show a bracket that they built to mount it in an RV-10, which is apparently a very different mounting than in the RV-14.

Does anyone have measurements or tips to help get the PH Aviation unit working properly in an RV-14? I don't want to put it in and find out many moons from now when I attach the wings that I am unable to fully retract or extend my flaps or that I have an over-center condition or other problem. Even just knowing the minimum and maximum angles that the CS-00010 flap torque arms should have relative to the fuselage would be really helpful.
 
PH Aviation Flap Actuator in an RV-14

We haven't had the opportunity to actually mount one of our actuators in an RV-14 yet, but we have looked at the drawings and it looks like the solution will involve moving the flap motor attach point about 1.5" higher up on the center post between the seats. This will probably require a redesign of the brackets or a modification of the kit brackets to shorten them the required distance. Also it looks like the distance between the brackets would need to be adjusted to the width of the new flap actuator. I think we would try to eliminate the factory brackets and redesign a couple of aluminum angles with enough distance between them to bracket the new actuator and move the attach point about 1 1/2 inches higher on the seat post.

The stroke of both flap motors is identical at 5", so the only issue is to position the attach point so that the rod end bearing ends up in approximately the same place as in the kit motor installation.

Here are a couple of photos showing the factory attach bracket.

RV14 Flap Bracket web.jpg


RV14 Flap Bracket2 web.jpg


I hope you will post your solution here later on for other folks to see. Thanks!
 
Hole-to-hole distance of the Vans RV-14 Actuator

We happen to have a stock RV-10/RV-14 flap motor that we use for testing. The hole-to-hole distance of the fully retracted flap motor is 10 1/4". That should help you calculate the position of the flap actuator arm (flap crank in the drawing above) fully retracted (flaps full down). Of course you should have some adjustment leeway in the flap linkage as well.
 
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Thanks for your replies. I'll document what I end up doing. The new flap actuator is at the post office so I haven't had a chance to look at it in context yet. The RV-14 flap motor brackets have lightening holes that eat up nearly the entire web, one of which is almost perfectly centered on the 1.5" mark from the stock flap motor attach point. So, if I use the stock brackets, I will have to add material. I hesitate to throw the stock brackets out, because they are perfectly engineered to fit and rivet on both fore and aft flanges, a level of structural integrity which I probably can't duplicate. I'll have to see if there is room to bolt a bracket onto the stock brackets to keep them in the loop.
 
Update: I clecoed the flap motor channel and brackets into place in the fuselage and measured. The gap between the brackets is 0.623" while the width of the end of the PH flap motor is 0.783". So the stock brackets definitely won't fit the PH flap motor, regardless of length. It looks like I will have to engineer and fabricate a mount for the PH flap motor from scratch. Now I won't feel so bad calling my plane an "experimental," since there are actual experiments involved. :)
 
A thought I had, can you narrow the end of the PH Flap Motor to match the width of the original Flap Motor bracket?

I have not seen the PH motor to make an evaluation.
Thanks
 
Following this install closely. Please be sure to share your solution. My stock flap actuator was b/o and I am thinking about the PHaviation actuator. If there isn't a clean install solution I think I will stay stock and avoid adding 1lb. I do like the simplicity of automatic stops and built in flap pos. It would be nice if PH would form and include the alum mounting brackets.

-Jason
 
The PH actuator is pretty beefy. I like it and I really like that it has a built-in position sensor. I hope I can make it work. I am motivated by the ego factor of having already sent the stock one AND the flap position kit back to Van's last week and not wanting to order them a second time. But I am nervous as I do not like cutting nice things and I do not know if I am up to the task of building new brackets that will have the strength of the originals.
 
I've been pondering the possibilities still. I took a couple pictures tonight and that has helped me brainstorm a bit. I'm posting my thoughts here in the hope I'll get some constructive criticism.

If you look at the top view of the PH actuator up against the stock bracket, you can see that the outside edges of the stock bracket are almost perfectly lined up with the actuator. If you look at the side view, it is about 1-1/2" from the stock mounting hole to the center of the lower (right in the photo) lightening hole. That is the difference in length between the PH actuator and the stock one.

Here's my current plan A:

1. Cut the stock brackets at the red line. This will leave both front-side (top left in the picture) rivets and two of the four back-side (bottom row in the picture) rivets intact. I will lose the two lower back-side rivets.

2. Cut some aluminum, probably from a piece of angle, roughly in the shape of the blue outline. One piece on each side.

3. Rivet the new pieces on the outside of the stock brackets, using the rivet locations shown in green. I will probably put thin shim pieces between the stock brackets and the new brackets in order to ensure there is sufficient room for the flap actuator, which is just a hair (0.021") wider than the outside edges of the stock brackets.

4. Mount the PH flap actuator at the position marked in yellow.

flap-bracket-top.jpg


flap-bracket-markup.jpg
 
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My two cents worth:

I think you need to expend the angle you use as indicated in Blue all the way upward. Thereby covering the two open holes. Riveting 3 places in total.

I hope I am clear in my thoughts.
 
Please ignore my previous post as I was mistaken as to what you were trying to do.
Sorry

I can't ignore your suggestion because it got me thinking. A wider piece of material could be riveted at more points to the original brackets. The better we spread the load to the airframe, the safer the solution ought to be.

I wish I could find a way to utilize all of the original rivet holes but I'm not seeing a way to improve my solution that would make use of them.
 
Ok,
Let us think in a different way.

Keep the original bracket but cut off the opposite end. ie.. What you have outlined in blue, move it to the right (picture) all the way to attach the PH actuator end and cut off the left portion of the bracket. Therefore you now have a shorter bracket to accommodate the difference for the length of the PH. Also, this will cause the new bracket to be wider to fit the PH unit. Now, drill new holes in different positions to attach the new bracket to the frame. I think you might still need the angle piece to stiffen the bracket.
What you think?
 
I can't ignore your suggestion because it got me thinking. A wider piece of material could be riveted at more points to the original brackets. The better we spread the load to the airframe, the safer the solution ought to be.

I wish I could find a way to utilize all of the original rivet holes but I'm not seeing a way to improve my solution that would make use of them.

Ari, I like your solution so far a lot. For the angle extensions I would suggest at least a 1" angle, perhaps 1 1/2", by 0.063", so you will have plenty of edge distance for the required 5/16" hole to attach the actuator. I don't think you can cut the existing bracket from the other end because that attaches to the crossover structure above the seat post as seen in the earlier photos. Looking good.

Suggestion: Resize your photos to 900 pixels wide before posting them and you will find that they size up much nicer on your monitor.
 
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Ari, I like your solution so far a lot. For the angle extensions I would suggest at least a 1" angle, perhaps 1 1/2", by 0.063", so you will have plenty of edge distance for the required 5/16" hole to attach the actuator. I don't think you can cut the existing bracket from the other end because that attaches to the crossover structure above the seat post as seen in the earlier photos. Looking good.

Suggestion: Resize your photos to 900 pixels wide before posting them and you will find that they size up much nicer on your monitor.
I'll have to see what angle material I am able to pick up locally. Any thoughts on those abandoned rivet holes?

As far as the picture size goes, I normally do fix that before posting but missed that step last night. I'm planning to re-do them in the near future so this thread isn't so annoying for people to participate in. :)
 
I'll have to see what angle material I am able to pick up locally. Any thoughts on those abandoned rivet holes?

What I would do is dimple and set rivets in them. You could also fill the holes with micro and sand them flush.

P.S. You might look around elsewhere in your kit for the angle material and replace what you use later from Spruce. :) Better yet, if you'll tell me how long they need to be I'll cut a couple of pieces for you and mail them to you.
 
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RV-14 Flap Bracket

Ari, here's a suggestion for trimming the bracket. It also utilizes a couple more of the existing rivet holes.

Untitled-1.jpg
 
Pat, I like yiur thoughts, I do not have the fuselage to understand the situation completely, so I made some wild ideas .
Thanks
 
Pat, I like your thoughts, I do not have the fuselage to understand the situation completely, so I made some wild guesses.
Thanks
 
Pat:

I like your suggested cut, which should still allow plenty of room for the small angle of pivoting that the flap actuator will need. I have one of the bracket pieces in my kitchen now so I'll remember to do some tracing, measuring, and drafting for the new brackets. That's one of my weekend projects, in between priming other pieces.
 
I'm thinking of using aluminum bar stock for the brackets. I will use some scrap aluminum sheet from my empennage kit to make shims that are about 1-1/2 inches wide and 2-1/2 inches long. Then I will use bar stock 1-1/2 inches wide and 3 inches long for the brackets. I drew this out and have more exact measurements written down, of course. A cut on the factory brackets based on Pat's drawing in this thread will let me use 4 rivets to secure the new brackets and shims to the factory brackets. This should be more than stable and strong enough for the flap actuator.

Any thoughts on thickness of the aluminum bar stock to use? Aircraft Spruce (from whom I need to order miscellaneous other things anyhow) has sizes from 1/8" up to 1" thick for 2024T3 material.
 
Any thoughts as to what you will use to fasten the aluminum angle to the
bracket?

I?m thinking of skipping the angle and using bar stock instead. But basically I will just rivet it together. I?ll take pictures of whatever I do to share here.
 
I ended up, with Pat's help, coming up with a good solution for the PH Aviation flap motor in an RV-14. I put together instructions with pictures in a PDF that I sent to Pat so future customers should get that with their order. If anyone wants it, you can send me a private message with your e-mail address. The end result is a pretty easy process.
 
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