I always thought that pan was there in case you wanted to wear a "sit on" parachute for doing aerobatics. Might be worth incorporating "easy removal" into your design.
I won't be wearing the old-style seat-type parachute. If I wear one at all, it'll be a back cushion type. And the seat pan change is permanent.
Frankly, I don't see what the fuss is about. Here are the RV-8 seat ribs, for example:
And closer to the RV-3B heritage, here are the RV-4 seat ribs:
The pictures are also lurking here and here.
Thanks to Rick Brennan!
Since then, progress has been made: the tapered pin is within 1/8”, which is about the axial equivalent, roughly, to the .004" diameter needed of being ready for assembly. The final eighth inch, though, needed another #3 reamer.
Once we got back together again, we followed this process. I’m starting at the beginning of the recovery here rather than the final 1/8”.
1. Secure the assembly on the mill.
2. Drill through the joint with the smallest drill that's close to the final size for the small end of the tapered pin.
3. Step drill the hole so that the drills don't exceed the taper wall sides, but going as far as possible short of that.
4. For the final reaming with a tapered reamer, put the reamer in a Tee handle.
5. Make a mandrel such that you can use a milling machine for pressure, pushing down on the reamer.
6. Press down on the reamer with the mill while a second person rotates the reamer by hand. For here on out, the mill is turned off. Use plenty of cutting oil. There is plenty of axial force on the reamer, and plenty of necessary torque on the Tee handle. Use work gloves. Only turn it in the cutting direction, even when pulling it out for a look.
7. Check often. But it goes slowly enough that if you do that, you won't exceed the tolerance. When checking, don't neglect to deburr the exit of the tapered hole. That burr hinders the assessment of the progress you're making.
And the bottom line is that this side is done, finally, after a LONG time of being unworkable. Thank you, Rick!
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.
Now both the seat and the baggage floor are pilot-drilled.
After this, I removed these and drilled the substructure for the nut plate mounting screws. No photo on the holes, and the hardware is on order. I did remove the flat seat ribs and added the nutplates to these, as it was easier to do that then do them in place.
With both landing gear legs drilled to the engine mount, I located and pilot-drilled the U-403 brake mounting fitting to the axels. Then, Rick and I drilled its mounting hole. The drills used were, in order and in inches, 1/8, 3/16, 1/4, N and finally the .311 reamer. I forgot to get a photo, but there wasn?t anything especially noteworthy about the set-up. Rick made some aluminum vee-blocks, which did a fine job gripping the axle. The 1/8 bit was in the pilot hole, which was just deep enough to locate it. We eyeballed the bit for verticality, rotating the axle as needed, and then went ahead and drilled it.
The landing gear is all going back to storage as I won?t need it for a while. The reason all this took place now was merely because it was easy to align to the fuselage at this stage. I?ll all in favor of making things easy. Besides, it's so much easier to rotate the fuselage when the gear legs aren't on it.
I found several smallish parts that haven't been plated yet, like the brake flanges and rudder cable straps, and got those ready for plating. I'd better have a look in the crates to see if there's anything else, too.
The photo is hosted here, too.
Here is the final seat riblet being glued in. I’m using a small heater to keep the epoxy warm and speed the curing.
Since that photo, I riveted them all to the factory seat ribs.
All the seat and baggage floor nutplates are finally riveted in. I thought that I’d need blind rivets throughout and ordered them for the job. But there’s enough access on most of the nutplates that I could squeeze regular rivets instead. Didn’t even use oops rivets. Instead I dimpled the nut plate tangs and dimpled the flanges of the ribs and bulkheads. Wasn’t a problem.
Well, not all of them. Some did need the blind rivets, those are done, and one location needs a one-lug nut plate, which I don’t have yet. But all the rest.
I formed the bottom ends of the seat back and drilled the pilot holes for the sides. That all was fun and went pretty quickly. Turns out that the formed fiberglass sear back top doesn’t fit very well. The bottom is bowed and the sides are too deep, and all that was on record in a build log about ten years ago. No change in the glasswork since. My kit is 2012, for reference, and even then it was a few years.
The seat’s positioning will need to be carefully done. In this photo, the flap weldment is simply placed in there in about the right position, and so is the seat. These will need to move around slightly, but it does give you an idea of the fitment situation.
Later, I bolted it down to ensure it's correct location, and discovered that I'd located the LH seat belt anchor in the wrong position - the flap handle interfered with it. Look carefully at Drawing 24, in the lower right corner. The two anchors are spaced differently, and I hadn't caught that. Email is in at Van's asking for advice.
One thing I was worried about turns out to be a non-issue: how to locate the holes in the fuselage bottom for the flap rods. With the flap handle in the full up position, there's absolutely no doubt where to start cutting. The fuselage is practically begging "here, cut here!" Later, though.
The seat back top is the white gel-coated fiberglass. I understand that the pink fiberglass is a newer generation, and the gray ones are the current newest. But for the RV-3 small parts, we get white. Regardless, it’s all doable.
More importantly, the as-received and as-drawn seat back seems to be 2.5” to 3.0” too high, also mentioned in a build log. Here it is from the front.
And from the rear side.
This is about where the seat back top needs to go. It should nest in the seat bulkhead like this.
To get that position, the seat back’s position will need to be carefully arranged.
The photos are also hosted on www.halie.com: this one, and this one, too, plus this and this one here, as well as one more and this last one.
I used a diamond hone plate (3" x 9") by hand to touch up the reamer cutting faces about every 3-5 revs. It really helped to get through the whole job with the same reamer. Only one was done, but likely it would do two. The larger diameter of the main gear would definitely be a challenge. Congrats on getting this done.
That's a good idea, Bill. You ought to put it in Tips. I'll bet it would help out a few people.
Outstanding workmanship, David.
I am impressed with your skill and patience. Will be a fine airplane.
Thanks for that comment.
Mostly I?ve been working on the flanges of the bulkheads for the top tailcone skin. The skin is F-323, for reference, and it?s .025 thick.
As Paul Dye noted during the construction of their RV-3B, the top sections of the tailcone flanges don?t really fit. At the longerons, they?re too narrow, all of them, and elsewhere they?re either too high or too low or poorly curved. First, I tried to correct the F-305 seat bulkhead and then the F-309 bulkhead, the aft most one that this skin attaches to.
Here?s the before and after photo of the seat bulkhead flanges at the longeron. The rest of that bulkhead isn?t too bad, and will be accepted as is.
The aft canopy latch goes through this one. It goes right through that gap between flange segments.
Then I did the F-309 bulkhead flanges. These needed thickening, not much, and rounding. I started with the areas adjacent to the longerons and filled the small gap with a thickened G-flex epoxy. It?s the same epoxy I?m using elsewhere with some flox and aluminum powder added for hardness. All it is, is a bit of a shim.
That worked out so well that I did the same thing to add some roundness to the too-straight flange segments. You can see that the topmost flange is essentially flat. I arranged the aluminum form so that it faired to the fuselage shape and at the top, faired to the seat bulkhead forward.
The blue vinyl is a decent release surface all by itself. To make certain, though, I put a couple coats of paste car wax on it. It came off with no problems.
The next bulkhead forward is the F-308 bulkhead. For this, I removed the flanges on that bulkhead. I?ll make totally new ones. The material thickness is .032 on this bulkhead, in case you?re ever in the same spot. The process I?m following is outlined this thread by Paul Dye and Louise Hose:
And I bought more magnets on order to hold the new flanges in place. I use p/n ZD84PC-PNK magnets from K&J Magnetics. They grip well, are easy to find when they jump away from sight, and seem to be very robust compared to the all-metal kinds. Recommended.
The plywood work platforms that I?ll need to squirm into the tailcone are all cut out now. I realized that although the flap weldment is not yet installed, the work platform needed to clear it when it was installed, too I had to trim it. Having flat seat ribs makes supporting the platform a lot easier in that area. Remember, on this airplane the seat pan is removable, so the platform could be handy one day.
The tennis ball protects the area around the control stick when the stick moves around. This sometimes happens when I roll the fuselage around. With a 1? hole the tennis ball goes right on.
So far I?ve only got part of one of the new flange strips cut out.
I strapped the tailcone top skin in place and was mildly surprised that it?s big enough. And even better, with some straps and cheap angles, it fits without needing rebending - the first curved fuselage skin to do so.
Here?s what the cave looks like. You can easily see where the new flanges will go and why they are needed.
Unfortunately the work platforms aren?t completely finished yet. It?s unfortunate, because I believe that the top skin is currently where I?d like it and I?d like to back drill some holes, and it takes climbing in the cave to do that.
You know, I?ve been thinking that I missed an opportunity to make the platforms fit the sides. If the fuselage was rolled on its side, there would be more width but less height and it might be easier to back drill the rivet holes. On the other hand, they'd be useless once I got the wings on, wouldn't they?
The work platforms got a final coat of finish after I took the photo, but it?ll be a day before they are dry enough to work on. I?m using Minwax?s polyurethane varnish. I?ve got plenty of experience with the product, with several of Minwax?s line, actually, and am happy with it. Their products go on well, cure quickly and are durable. And the best part is that I had a can on hand from a different project.
The alternate hosting links are -
and the eighth and final one.
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