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Old 04-30-2019, 06:26 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054
Default Deep In the Cave

Got to say that it?s getting narrow in here. The cave is the tailcone; I?m in it as far as the F-309 bulkhead, where my shoulders are wedged. The gray things on either side are my elbows and arms as I was holding the camera over my head. We?re looking forward.

The bright white circle is a lamp. It?s off right now but its reflector did a good job with the camera?s flash.

You can see the back side of the F-308 bulkhead, then the seat bulkhead, and out in the open, the instrument panel. It ought to be apparent why RV-3 builders need to remake the fuselage bulkhead flanges. And if you look closely, you can see that the F-308 bulkhead still needs to be joined - it?s splice plate is made and drilled but not installed.

Right now, the top tailcone skin is clecoed from the front back to the F-308 bulkhead.

Just thought that you might enjoy the view from the cave.

The photo is also here.

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Old 04-30-2019, 08:42 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054

Tonight, I crawled into the tail area of the fuselage to back drill the rivet holes from the front and back bulkheads and the longerons into the top skin. Since there are no flanges on the middle two bulkheads, F-308 and F-309, all I did was the perimeter.

From the work platforms, I could drill back to about the static ports, maybe slightly farther. For the aft-most, I figured that I could round up one of the neighbor kids. It turned out that with a longish bit in the 90 degree angle drill, and some effort, I could drill the aft-most bulkhead and the nearby longerons through that bulkhead.

Yes, somewhere deep in the cave, I made a blood offering to the gods of the sky. Did not plan that.

Some trimming will be required.

The photo is also here.

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Old 05-08-2019, 08:35 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054

With the help of my mentor, I made a list of things that need to be done before I glue the turtledeck on.

1. Cut the slots for the shoulder harness. They need to clear the as-yet undesigned canopy frame.
2. Install or at least prep for the transponder antenna. Install the transponder mount if access will be restricted later.
3. Make and fit the baggage compartment aft bulkhead.
4. Install the ADAHRS mount and maybe the ADAHRS, too, depending upon access.

You might recollect the ADAHRS brackets I’d made earlier.

It was intended to rivet these brackets to the aft face of the F-308 bulkhead, fairly high, so that it would be out of the way for cave access and away from magnetic interference. Turns out that while it would function fine there, mounting it to the 1 degree alignment accuracy would be a very iffy proposition, perhaps more frustrating than fun. I’m only building this plane for the fun of the project, so I need to design something easier to align. As the project progresses, my frustration tolerance has not increased. I’m just more used to it. It looks as if I can get the ADAHRS close enough to the tail for access through the F-309 bulkhead, the one at the top front of the aft shelf, if the elevator pushrod isn’t in the way, which I think it might not be. It appears to go through the next hole down. The ADAHRS would be accessible through the bulkheads’s top lightening hole.

After considerable hand-waving and playing around with pieces of angle, I came up with an ADAHRS mount that has the reliable alignment I wanted and continues the slide-in removal feature of the first version.

It is easily removable through that top lightening hole, as hoped.

The photos are also here, and here, too.


Last edited by David Paule : 05-09-2019 at 08:46 AM. Reason: Removed stuff previously posted, sorry.
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Old 05-12-2019, 03:55 AM
RV3Kev RV3Kev is offline
Join Date: Sep 2017
Location: Traralgon Australia
Posts: 46
Default Rivet + Adhesive ?

Dear Dave

Why the adhesive plus riveting? Using adhesive adds weight so I'm assuming that there is some net benefit.

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Old 05-12-2019, 08:09 AM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054

Kevin, It does a couple of things besides absorbing time and money and supplying weight.

The big thing is that it fills small gaps that might otherwise exist in the airframe. The RV-3B has many of those, or at least mine does; maybe not so much for a better builder. The glue acts as a sort of liquid shim.

The second thing is that once things are glued, they can be riveted at leisure and there aren't any clecos to mess with. It's a great holding fixture. Just don't forget the rivets.

Here and there, mostly for small things, I'm skipping the glue. The ADAHRS bracket, for example, isn't glued. But most of the fuselage and certainly all the fuselage skins are glued.

I regret not gluing the wings and tail. On the other hand, they're done and they might not be if I were gluing 'em. It sure adds to the time involved.

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Old 05-12-2019, 08:13 AM
ColoCardinal's Avatar
ColoCardinal ColoCardinal is offline
Join Date: May 2010
Location: Morrison, CO
Posts: 372
Thumbs up

Looking great David. It is tough work avoiding
"painting ones self into a corner" on a project such as this. Thanks for sharing, once again.
Carl - - Morrison, CO
Airworthiness cert issued 12/24
best X-mas present I could have hoped for!
paid 'til 10-19
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Old 05-14-2019, 08:37 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054

The ADAHRS mount is complete and aligned. This photo was taken after riveting.

You might have been wondering how I?d hold in in place, and assumed I?d put screws through the holes on the flanges. That probably would have worked but it wasn?t my plan. I felt that it would be too hard to install a screw and a nut, probably nylon or brass, with one hand working through that bulkhead hole. If you look into the hole on this photo, you?ll see that it?s terribly misaligned.

The misalignment was intentional. The idea is to thread a ty-wrap through it, around the front of the unit, and snug it up from the back. This can be done, I tried it, but it isn?t all that easy. But it works. The ty-wrap pulls the ADAHRS forward against that front stop, which serves both to locate it in yaw and position it longitudinally. There?s a ty-wrap on both sides for a little extra security. This is shown with loose ty-wraps in the next photo.

Moving on to the baggage compartment close-out, which needs to be removable, the manual lists three drawings that supposedly describe it. In fact, none of them refer to it at all. But the RV-4 and RV-8 preview plans say it uses #8 screws. They don?t say how many. Since it?s not structural, I arbitrarily chose to use four of them.

Here it?s shown fitted in place. Amazingly, it fits. It?s not pretty but it fits. I was astonished. Since it does fit, I can almost forgive the poor formed shape that it has. I?d like to see the tooling that produced that. Take a look around the top contours to see what I?m referring to. Isn?t that something?

Well, no complaints here. I signed up for this with a good idea of what I was getting into. I did have to trim the bottom edge to clear the floor.

There?s zero chance of merely dropping a screw from the close-out into the surrounding bulkhead because although it fits, there?s little in-plane overlap. Brackets are required, so I made four and glued and riveted them on. Here, the glue might help with the overhang. The brackets attach to the front surface of the close-out and extend past the peripheral rim to the bulkhead. The bottom nutplates were installed but at the top, the plywood bulkhead stiffener prevents that for now.

I made the transponder antenna doubler and riveted that in. Thanks to Rick Brennan for bucking help. It?s the gray rectangle above the elevator pushrod.

I?m using Delta Pop?s ?Ultra Low Drag? antenna, and a pretty thing it is, too. But I?m not mounting it yet.

Incidentally, I checked with the manufacturer of the antenna about priming the skin or the doubler. He said that with hole-filling rivets (that is, the rivets we use) people report good results. Also the antenna base is plastic, not metal.

The left-hand seat belt anchor was mislocated originally. I moved it inboard to a new location, after getting some advice from Support. Thanks Van?s - seven years after buying the kit, they?re still supporting a discontinued model.

And finally, I figured out where to put the outside air temperature sensor. I understand that there are as many opinions about this as there are RVs, so I took my mentor?s advice, and placed it on the F-310 bulkhead, at the forward end of the aft shelf. It?ll be under the tail fairing and easy access to the nearby ADAHRS.

The secondary photo hosting is at here, here, here, this place, and yeah, here, too.

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Old 05-29-2019, 01:22 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054

With the seat belt anchor relocated, it was time to adjust the seat back so that it clears. A slight bit of carving on that 45 degree flat area and that was done. When I went to fit the piano hinges, I found that the good extruded kind had mysteriously lost its pin. A replacement pin is on order.

The upper end of the seat back side rails needs trimming and the inside of the seat bulkhead, too, to allow the seat back?s fiberglass top to fit into the upper part of the seat bulkhead. For a relatively simple part, the seat back sure wants a lot of miscellaneous fitting. Worth mentioning is that the top of the F-328A seat back is approximately 2 1/2? too high and also needed trimming.

Here?s the bottom. Only the left side needed trimming, the right was fine.

This shows the flanges of the seat back rail and the bulkhead. Both need further trimming.

After placing the fiberglass F-328C seat back top in position, I was able to draw the area of the bulkhead top in which the shoulder harness slot gets cut. You might remember that I?d left that till now just in case, following one of the RV-3B Build Commandments: Do not do anything until you must. The other one is: Do what you can early because you might not get access later. Yes, these conflict with each other, part of the fun. In this case, waiting was worth it.

The shoulder harness slots are detailed on drawing 21. The local reinforcements looked annoying to make. The RV-4 plans show that part in more detail as F-407D, which is a DIY part. If you want to make the part, follow that drawing. It?s not on The List of parts that Van?s sells, being a DIY part on the RV-4, too. ?The List? is their nomenclature, not mine, if you?re not familiar with their parts ordering system. Fortunately I?ve got the RV-8 plans as well as the RV-4 plans, thanks to their handy flash drives. The equivalent RV-8 part is F-807D-1, for $2.40. Hoping it?s the same part, same fit, I ordered a pair. We?ll see.

This shows the F-407D detail.

I placed the slots horizontally rather than aligned with the curve of the bulkhead, thinking that my shoulders, sag though they will, are closer to that than to the bulkhead curve.

Remember those flanges I needed to make for the F-306 and F-308 bulkhead tops? After a number of trips into and out of the cave-like tailcone, they are all finally fit, drilled and clecoed in place. Not ?are,? ?were.? For I glued them to the bulkheads and then riveted them. Not especially pretty but, I hope functional.

A while ago, I?d made a cardboard mock-up of the EarthX battery. More recently I found that they sell an empty battery case, so I bought one. Good service - it came the next day; they are somewhat local. Tried to find a place to fit it and hold it down, a place where it and the contactors are reasonably close and not immediately adjacent to fuel lines. Have a partial plan but it?s not this one. This was one of the options I did not choose. It placed the parts within a few inches of the fuel lines.

That?s the firewall and its recess to the left, with the spar bulkhead on the right. The battery case is resting on the forward floor. One rudder pedal is just visible at the bottom. The contactors are shown upside down, as I learned after I'd taken the photo. They are rather close together only because the bit of scrap they're clamped to here, was that long. This was just to assess the location and mounting.

The photos are also hosted here, here, here, here, here, and finally, here, too.

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Old 06-10-2019, 08:56 PM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,054

Here are a few photos showing the seat back as it fits inside the cockpit.

This shows the clearance at the lower left, where I had to relocate the seat belt attachment.

The bottom back of the seat back clears the flap bar. But after adding the .040 shims per the manual and the piano hinges, there’s that much more clearance than shown.

The sear back folds forward to allow some limited access to the baggage compartment. Here it is folded forward.

Here is the seat back from the front. Points of interest are the bottom corners at the seat belt attachments and the clearance to the seat bottom.

As of right now, the aluminum frame of the seat back is all riveted. The fiberglass part is not yet permanently attached. I started by blind riveting and after replacing a few rivets, ended up doing it with the gun in one hand and bucking bar in the other. Surprisingly, that worked better for me.

I had one of Flyboys pneumatic tailwheels on order, and it arrived. Here it is disassembled. They recommend 50 psi and based upon my experience with my certified airplane, I feel that’s a very good pressure to start with. Note the sealed bearings.

As is my habit, the photos also lurk in this place, and that place, and another place, and this place, too, and finally this last place.

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Old 06-13-2019, 04:46 AM
Snap Snap is offline
Join Date: Aug 2017
Location: Germany / USA
Posts: 93

Originally Posted by David Paule View Post
I bolted the engine mount on again and rigged the right gear leg and pilot-drilled it to 1/8?. This photo shows the drill guide I used - I made it. Later, Rick drilled and reamed it out to .311, and the close-tolerance straight pin is a tight fit.

After double-checking that the seat pan and baggage floor patterns that I?d made actually fit, always worth doing, I cut them out. The baggage floor is in two pieces to make them easier to remove. After some work the pieces are deburred, bent and clecoed in place. The flanges were bent before the overall curves, and those were bent before I drilled the holes.

I didn?t mean to, but the landing gear and the floors are going on at the same time. Actually they take turns, but they?re both up for attention now. At the moment, the floors are getting some work.

Thought you?d like to see one of the shop tools in use. The shop vac in the foreground is probably the most common tool that I use since I hate to track aluminum into the house. Once in a while, though, I let the Roomba robot vacuum run around and get the bits I miss. I replaced its battery and it seems to go on forever now.

If the photos should disappear, also try

this place, this other place, and this place, too.

Great read, Dave!

To which angle / track / toe-in or out did you set it up? 0 on everything without any load?

"Nothing is more powerful than an idea whose time has come." (Victor Hugo)
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