the tiny little "flap pushrod egress" hole

was this a joke?

I have not yet started making the large, oddly-shaped holes on either side of the the fuselage... and I'm not sure where to begin really. I did call the Mothership to find out what they had in mind-- there must be a better way than starting with a small hole that the flap rod fits through and enlarging it until it doesn't hit anywhere.

I'll pay for a good template. I would. I'm not kidding.

Someone has a better way. I'm sure of it.

What have you done here?

Hi Bill,

This should help...

http://www.vansairforce.com/community/showthread.php?t=11690&highlight=flap+pushrod+cutout

Bill,

Also keep in mind the (9) uses a hex stock instead of the smaller aluminum tube on the (7) so pay more attention to the (7) drawing. Many feel that the (9) hex stock is stronger than the small tube used on the (7) and you can order them and go that route if you like.

Here's my approach...

No template. There's slight but sufficient variation between all the structures involved that you really want to trim it to fit. And it's not that bad at all if you take a methodical approach to it.

Here's what I did, which worked well:

First of all, if you haven't already trimmed the flap inboard edge to clear the fuselage, do it now before you proceed.

Now, forget about that little guide notch that Van's pre-punches in the fuselage side skin. It's pretty close to the right place, but not all that useful as a starting point. For a better starting point...

... install the rod end bearing only (no pushrod) into the flap, and install the flap to the wing. Let the threaded shank of the rod end bearing lay back (facing aft) out of the way. Now hold the flap up as far as it goes, which will be limited by the rod end bearing hitting the bottom fuse skin. Mark its outline on the fuse skin, and then cut it out.

Now the rod end bearing should be able to slide through the fuse bottom skin (shank first) until the stud portion of it that threads into the flap hits the fuse side skin. Again, mark it, then cut. Be conservative (don't cut too much at once) and allow for a couple of iterations of cutting, checking, marking and cutting some more. Get to the point where the rod end bearing can penetrate the fuse with no interference, and so the flap can go all the way up.

Now with the flap in the "up" position, install the push rod connecting the flap to the torque tube. Start to lower the flap gently until the push rod hits the side of the hole in the bottom fuse skin. Mark the area of interference, and trim. Now you should be able to lower it some more. Repeat until you can lower the flaps all the way down with no possible interference anywhere along the way. You'll end up with kind-of-a peanut-shaped hole.

This process is a bit iterative, yes. But this way the hole will be no bigger than it needs to be. You won't get results that accurate from copying a template from a different airplane, or even from one side to the other of the same airplane.

Good luck.

I just made my holes this past weekend. If you would like, Im not sure how much help it would be but you can check out my pictures HERE I also choose to go with the Hex rods, mine came from avery tools for $16 for both.

-david

Roee,

Why did you trim the inboard part of the flap to clear the fuselage (I presume you are talking the bottom skin on the flap)?

greg

Here's the plan

1. Install the bearing into the flap
   
2. cut a template that clears the bearing and tape it to the bottom flap skin such that the tape can be removed and re-taped to the fuselage.
   
3. remove the bearing
   
4. retract the flap (well... push it into a retracted position)
   
5. un-tape the template and re-attach it to the fusellage (releasing the template from the flap.
   
6. extend the flap and cut initial hole in the fuse bottom skin. My initial side skin hole will be cut as tall as the bearing in assembly on the flap or slightly less. Only as tall as the spherical bearing part-- not the threaded portion.
   
7. Then I'll clearance the flap rod through trial and error.

Does that sound about right?

Greg Arehart said:

Roee,

Why did you trim the inboard part of the flap to clear the fuselage (I presume you are talking the bottom skin on the flap)?

greg

Click to expand...

Greg,

I can answer that one for you -- (sorry for jumping in, Roee).

On the -7 and -8 (and maybe others), the top skins of the flaps are intentionally built too long and have to be trimmed several inches to match the contour of the fuselage. Hope that explains it.

QUOTE=BuckWynd;527988]Greg,

I can answer that one for you -- (sorry for jumping in, Roee).

On the -7 and -8 (and maybe others), the top skins of the flaps are intentionally built too long and have to be trimmed several inches to match the contour of the fuselage. Hope that explains it.[/QUOTE]


I didn't find this to be true for my kit (72532)

after hanging the aileron, gapping the aileron to flap at a quarter inch I only had to remove about 1/8 of an inch to get a uniform 1/8 inch gap between the flap top skin and the fuselage side skin. Some carefull file work and the scotch brite wheel make short work of that. The bottom flap skin is longer and overlaps the belly like you say but also doesn't need any trimming.


I guess it's possible that some aircraft don't need any trimming at all to fit the flaps, but my flap top skins did require a tad.

Is this something that has evolved out of the kits over time?

My experience was the same as Bill mentioned. Very little filing for a good fit. I haven't cut my holes yet though as a result of my push rods misplacing themselves during the wing fit.

Ok, thanks. I was thinking that folks were trimming off the bottom skin of the flap so that it would (possibly) go past "full up." Thanks for the clarification.

greg

I did the slow, careful, iterative work cutting the hole on the first one. It's an odd-shaped hole. It came out great.



Then, I made a paper template from the first one to use on the other side. Why repeat all that work? The plane is perfectly symmetrical. At least, in my case.



I have lots of pictures and a detailed discussion of how I did this on my log page here, including the tools I used:

Cutting Flap Egress Hole, using a Template

I recently gave my template to a local friend building an RV-7A. I'm anxious to hear how his turns out.

About trimming the flap skin...

... yep, I was referring to the top skin, as others have noted. Not the bottom skin. And it only needed to be trimmed about 1/8" at most.

instructor_bill said:

I didn't find this to be true for my kit
<snip>
The bottom flap skin is longer and overlaps the belly like you say but also doesn't need any trimming.

Click to expand...

Interesting. My kit is 2006 vintage, so perhaps there have been some changes. My plans show at least 2" needs to be trimmed off the flap's top skin along a curving line. I'll be doing the flaps in about a week, so I'll be interested to see how much will actually need to be trimmed.

Thanks Bruce and Reiley and Roee

Not as bad as I had thought.

I used parts of Roee's technique, referred to Reiley's provided link and Bruce's info about transferring the template from side to side.

What I have now is two very nicely done flap rod egress holes.



thanks guys!

instructor_bill said:

Not as bad as I had thought.

I used parts of Roee's technique, referred to Reiley's provided link and Bruce's info about transferring the template from side to side.

What I have now is two very nicely done flap rod egress holes.



thanks guys!

Click to expand...

Awesome... just makes you feel good.

Necropost - thanks for the pics guys, I'm at that point now and was really scratching my noggin. It's all becoming clear now...