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Rear Avionics Shelves

Brantel

Well Known Member
I am working on fabricating the rear avionics shelves that I want to build into my tail cone while everything is wide open.

I want to do something similar to this:

equipment%20tray-4.JPG

Image from http://www.tcwtech.com

I plan to do a similar shelf on each side and have been using a cardboard template to layout my plan.

m4LHhEDl.jpg


I do not like the idea of uncurling the J stiffener like TCWTech did so I rolling my own way of connecting the edge of the shelf to the J stiffener.

3R8S3iQl.jpg


When the shelf is level in both directions it does not align with the J stiffener so this misalignment must be compensated for. Here is what I have above which is hard to see:

97CFSUNl.jpg


I don't like how little force it takes to start to move/rotate the J stiffener. I know that once it is all locked together it will tend to minimize what I am seeing now but I still don't like it.

That being said I am thinking of adding either one or two ribs under the shelf and connect them to the bottom skin J stringers.

5Hj541gl.jpg


TtrLNjml.jpg



Anyone see any issues or a better way to tackle this? One rib or two?

I will likely use low weight EarthX or similar batteries so the additional weight is less of a concern for me.

Sorry for the napkin CAD!
 
Sooner or later you?ll have to get back in the tailcone. Make sure it?s not too hard.
A few weeks ago someone posted that they had a remote magnetometer in a similar location, and putting his steel towbar into the baggage area affected it.
Just things to think about.
 
Sooner or later you’ll have to get back in the tailcone. Make sure it’s not too hard.
A few weeks ago someone posted that they had a remote magnetometer in a similar location, and putting his steel towbar into the baggage area affected it.
Just things to think about.

After entering that position on the RV-7 many times I am familiar with this appropriate warning! It is not if, it is when! The goal is to make it fairly easy to go over these shelves if needed. They will also be removable for hard core work.

I learned a trick to crawling into tail cones that works great and minimizes the chance for damage. I use a leaf bag with just the right amount of foam packing peanuts to put down under the board I crawl on to distribute the weight. It works amazingly well!

Likely I will mount the magnetometer in the wingtip.
 
I was going to chime in on the access issue. I only have a tray on one side of the battery. My adahrs are hanging on a tray at the bulkhead where your plywood stops. It's painful for a big guy like me to get around the batteries, let alone if there is anything else in the way.

Fortunately, I've only had to do that twice. Once when an original magnetometer died and the second time when I upgraded them to adahrs.
 
I was going to chime in on the access issue. I only have a tray on one side of the battery. My adahrs are hanging on a tray at the bulkhead where your plywood stops. It's painful for a big guy like me to get around the batteries, let alone if there is anything else in the way.

Fortunately, I've only had to do that twice. Once when an original magnetometer died and the second time when I upgraded them to adahrs.

+1

Having just crawled back there to do my static ports, I would not want that in my way. It is very difficult for a big guy to get back there and I am dreading bucking the rivets for the last top skin. Think about how you would crawl over that. Especially if you have a magnetometer hanging from the top z brackets and a large hose and valve back there as well for the overhead. Gets crowded quickly.

I hung the ELT on the side skin z brackets.

Larry
 
Its all removable for those rare occasions.

I am willing to put up with that minor occasional inconvenience to have plenty of space to mount components.

All systems seem to be very modular these days and having options of where to mount stuff is what I am after.

My magnetometer will go on the wingtip. I don’t really understand the need for the vent valve since the eyeball vents can close. I don’t have a valve on my RV-7 vents, just the good eyeballs that seal off very well. What am I missing on that?
 
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why not just use the plans the Bob posted on the TCWTech website? Worked great for me. Easy to make.
 
Here's what I did:

ztay4m.jpg


jzh9jr.jpg


The ribs were made from an extra set of the ones under the battery.

==dave==
 
why not just use the plans the Bob posted on the TCWTech website? Worked great for me. Easy to make.

I used some of his design. I did not want to cut and unroll the J stiffeners. I also did not like the amount of flex that I was seeing with light pressure.

I am almost done with the fab of the right side. The left will go faster. The napkin CAD design above seems to be working out fine. It is very stiff.
 
Here's what I did:

ztay4m.jpg


jzh9jr.jpg


The ribs were made from an extra set of the ones under the battery.

==dave==

I liked your idea allot. I almost went that route with the ribs. Came close to contacting you to find out how you made em. I already had stuff to fab up my own so I just decided to make em.

I went ahead and also tied the sides into the sides of the fuse just to have complete continuity.

This looks like it will be strong enough to crawl on.
 
I found I liked the side mount plates better for some things:

2zocgoo.jpg


2efu9z4.jpg


I like your leaf bag w/peanuts trick...hoping I don't have to try it.

==dave==
 
I found I liked the side mount plates better for some things:

I like your leaf bag w/peanuts trick...hoping I don't have to try it.

==dave==

I have a couple those on the way as well.

It?s almost inevitable to have to crawl in there sometime. I have been in my RV-7 at least a dozen times with all the upgrades it has been through.
 
Its all removable for those rare occasions.

I am willing to put up with that minor occasional inconvenience to have plenty of space to mount components.

All systems seem to be very modular these days and having options of where to mount stuff is what I am after.

My magnetometer will go on the wingtip. I don’t really understand the need for the vent valve since the eyeball vents can close. I don’t have a valve on my RV-7 vents, just the good eyeballs that seal off very well. What am I missing on that?


If it is removable, then seems like a good idea. I was advised by several others that slight leakage from the vents right next to your face in the winter can be annoying, hence the valve. None of them are leak free. However, on the 6/7/9 they are far enough away to not make any issues. However, when only 6" from your face it's a different story. I can't speak from personal experience, only sharing experiences learned from others. i thought the cost was steep, so I made my own valve/servo.

Larry
 
If it is removable, then seems like a good idea. I was advised by several others that slight leakage from the vents right next to your face in the winter can be annoying, hence the valve. None of them are leak free. However, on the 6/7/9 they are far enough away to not make any issues. However, when only 6" from your face it's a different story. I can't speak from personal experience, only sharing experiences learned from others. i thought the cost was steep, so I made my own valve/servo.

Larry

Well I had not though of that. I have never noticed any air coming from the Stein vents when closed but like you said, I don?t have my face right there.

Hmmm...

I would likely make my own as well. Any details on how you made the valve posted anywhere?s? Servos and servo controllers I have experience with.
 
Well I had not though of that. I have never noticed any air coming from the Stein vents when closed but like you said, I don’t have my face right there.

Hmmm...

I would likely make my own as well. Any details on how you made the valve posted anywhere’s? Servos and servo controllers I have experience with.


Mine is now mounted, but will take a pic later today.. I just looked at a pic of the one being sold and drew something up. I made a similar oil cooler air valve as well. Using a lathe and mill, I was able to get a pretty tight seal. I made two, but ended up only doing one naca for the o/h console.

Larry
 
It?s not necessarily that the vents will leak, it?s that the switches and lights leak, along with the door pneumatic bracket that penetrates the overhead. You?ll never notice it till it?s really really cold.
 
It’s not necessarily that the vents will leak, it’s that the switches and lights leak, along with the door pneumatic bracket that penetrates the overhead. You’ll never notice it till it’s really really cold.

That’s another good point. I knew the answer was simple, just had never considered those two issues.

Thanks guys for continuing to share what you all have learned with the newer builders. Some of the good stuff is getting lost in the noise with the 10 design getting some age on it now. Old threads like so many others are losing their value since pics are missing on more and more of them. Seems the Matronix list is all but dead these days.
 
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After a bit of work Friday evening and allot of work Saturday I have the shelves all fabbed up. All that is left is the priming, riveting and adding the nutplates.

Due to the flex I was seeing I went ahead and tied the shelves into the fuse side and bottom J stiffeners. The bottom got 4 homemade ribs that I cut lightning holes in.

While these will be removable, they are very strong and likely will be fine to crawl on.

pQxSbzKl.jpg
 
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