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  #1  
Old 08-21-2021, 04:55 PM
moespeeds moespeeds is offline
 
Join Date: Apr 2021
Location: west berlin
Posts: 64
Default Bent flap actuator rods (purposely) and other flap questions...

During the pre-buy on my RV8 we noticed the flap actuator rods were bent for clearance. I figured I'd just correct the issue later.




Today I'm installing the PH Flap Motor and decided to put the straight rods in while I'm at it. I now see why they were bent, the angle a straight arm needs to follow is nowhere near where it needs to be. It's much worse on the left side.

Opening up the through-hole is not an option as I'd need to cut up higher into the fuselage side, and I'm already at the max without cutting into the flap stop.

These photos show the issue:



So I see my options as:
#1 Leave the bent rods in, they've been working just fine for 380 hours

#2 Space the rod outboard down at the flap, but how far out could I go down there? I could also weld or modify the big white actuator that moves both flaps. I'm a very competent welder it would be no big deal to fab and weld new arms or spacers on the inboard side of the existing arms, but then how much will the arm protrude into the cockpit with the new angle?



Next question, specifically regarding the PH Flap Actuator. How much play should there be in the whole system? The builder left all the rod ends with no spacers so they could float back and forth along the bolts holding them to the actuator arm. Same with the motor to arm connection. If I slide washers in there to remove all the side-play, I get a lot of drag on the whole system which I'm sure isn't good for the motor.

Also, should I rig the flaps to pull tight right up against the stops on the fuse, or leave a small amount of play in there? When you grab a retracted flap, should it have any slop in it at all?

Thanks in advance guys
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RV-8 N495T
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  #2  
Old 08-21-2021, 05:33 PM
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Ironflight Ironflight is offline
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Location: Dayton, NV
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Default

This one is puzzling, and a bit troubling Moe - I have never heard of anyone bending those pushrods to make them work on an -8, and I would be fairly nervous about doing so, since they are tubes in compression. Granted, the hexagonal tubs are a lot stronger than the aluminum cylinder tubes used originally, but there can be a lot of compressive force on them from deployed flaps, and having one decide to buckle could make for an interesting ride if you were down low.

The puzzling part is, as I said earlier, I have never seen a case where sooner had to bend one to get the clearance to work out in an -8. See if you can find another -8 nearby to look at and see how the holes fit. Most people have to open them up a bit in one direction or another - but they always seem to fit within the fairing.

More investigation is warranted.

Paul
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  #3  
Old 08-21-2021, 06:23 PM
Kyle Boatright Kyle Boatright is offline
 
Join Date: Aug 2005
Location: Atlanta, GA
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Quote:
Originally Posted by Ironflight View Post

The puzzling part is, as I said earlier, I have never seen a case where sooner had to bend one to get the clearance to work out in an -8. See if you can find another -8 nearby to look at and see how the holes fit. Most people have to open them up a bit in one direction or another - but they always seem to fit within the fairing.

More investigation is warranted.

Paul
Where do the holes normally exit the fuselage on the -8? On the -6, they exit right at the junction of the bottom and side skins. I absolutely hated cutting that opening.
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  #4  
Old 08-21-2021, 06:55 PM
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N184DA N184DA is offline
 
Join Date: Jun 2007
Location: Tacoma, WA
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Quote:
Originally Posted by Kyle Boatright View Post
Where do the holes normally exit the fuselage on the -8? On the -6, they exit right at the junction of the bottom and side skins. I absolutely hated cutting that opening.
Same with a 4,,
And my left & right are not exactly the same.
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  #5  
Old 08-21-2021, 09:04 PM
moespeeds moespeeds is offline
 
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Location: west berlin
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Another option would be to just swap the aluminum rods out with steel and bend them the same way. Other then getting into spacers or surgery on the Vans supplied actuator weldment I don't see another way to do this.
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RV-8 N495T
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  #6  
Old 08-21-2021, 10:12 PM
gasman gasman is offline
 
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Maybe look over the plans, make repairs to the fuselage and install the pushrods I.A.W. the plans.
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  #7  
Old 08-22-2021, 12:09 AM
Taltruda Taltruda is online now
 
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Does anybody know if the RV-7 flaps maybe shorter than the -8? Perhaps these are shorter flaps and that’s why they have that doubler on the inboard end? I’ll take some pictures tomorrow and try and post them.
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  #8  
Old 08-22-2021, 09:58 AM
butch 76 butch 76 is offline
 
Join Date: May 2018
Location: medford, or. 97504
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Default bent flap rods

haveing been in 7 rv8 builds, all have bent flap flap rods, out of 4130 rod.the reason is to keep from in my opinion from unnecessary cutting on the fuselage.
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  #9  
Old 08-22-2021, 09:08 PM
Sam_B Sam_B is offline
 
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Location: Boyceville, Wi
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Default Not totally clear

I think from the image that you show that the rod is bent more forward on the bottom portion, but it isn’t totally clear…. Is it bent more outward on the bottom portion instead? If so, I do remember the plans allowing for a washer to be used when threading the tie rod end into the flap to space it more towards the fuselage. I don’t have the plans in front of me, but check them if the latter is the case. If the former is the case, then sorry, I haven’t a clue how to proceed.

Good luck,
Sam
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  #10  
Old 08-22-2021, 09:32 PM
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Don Patrick Don Patrick is offline
 
Join Date: Feb 2010
Location: GTA, Ontario
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Default Build it right.

I followed the plans on my 8….no bending of the rods required.

Don
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