Rick6a

Rick6a

Well Known Member
I received the -8 fuselage kit 10 days ago. With most of the subassemblies now complete, I will soon be moving everything from the basement to the garage where it will reside for the remainder of its assembly. I'm at the point where the plans call for spacers to be installed in the center section to simulate the thickness of the spar and if desired to extend them so optional legs can be attached for support. Do those who have gone before........do you find this a desirable thing to do or not? I'm thinking when the time comes, I may want to mount the fuselage on a rotator. Thoughts?
 
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I did not attach any legs to my spacer blocks, Rick, and am very glad I did not. Once you get to the point of mounting the wings you'll have to have to get the spacers out of there and you'll have to find some other way to hold up your fuse. I built a basic rolling fuselage stand in about 2 hours (design from Bill Repucci) that allows both general building and wing mating. Highly recommended as an alternative to attaching legs to your spar spacers. Good luck.
 
made mine from alu blocks

i had the machine shop at school make them out of alu block then bolted some legs to them. just didnt see how the dimension wouldnt change over a period of time if used with wood and bolted together. when i slid my wings in they went in perfectly and no problems at all. the rotating stand would be a huge plus.
 
Don't know if it would apply well to an 8, but on my 4 I took a couple of lengths of steel angle stock and bolted them vertically to the engine mount holes. I had to use some little spacers to get them about 1/2 inch off the firewall. Make em as long as you need and even put wheels at the ends if you like. Very cheap and easy.
 
I milled aluminum spacers with drilled and taped holes in the ends for legs but did not end up using the holes. I just put the fuselage on some blocks of wood at the height I liked.
 
Wing Spacer

I used milled alum spacers as Paul did above. I used 1 1/2" square tubing bolted onto the end of the spacers for legs. Make the length of the legs so that you can work comfortably inside the the plane while bending over from the outside.

Make another set of legs long enough to get the plane high enough while it's upside down so that you can align the gear legs to drill the bolt holes for the gear clamps.

I used to have a set of drawings that showed the exact dimensions and hole placement. May still be in the hangar. If anyone wants them, I'll look for them tomorrow. I got them from someone's website 4 or 5 years ago.
 
False Spar Tolerance

Hi folks,

I machined spar blocks out of well aged maple. I took one too many passes over the joiner and ended up about .006 thinner than 1 7/16. Not having seen how this all fits together in the end, I am wondering if that is too thin and if I should do it over? The real question is, what is the tolerance to which the spar/center section fits? Is there any give to it? I could see machining blocks out of aluminum as described above, but that would be a big job for me. Anyway, I can't decide if this is my obsessive/compulsive disorder out of control or a really good idea to get it exactly perfect. Thoughts?

Michael Wynn
RV 8 (Pre-punch) Fuselage
San Ramon, CA
 
mlwynn said:
....I machined spar blocks out of well aged maple......and ended up about .006 thinner than 1 7/16.....
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Mike,

Personally, I'm not going to obsess over it. I don't know how your kit assembles but when everything is temporarily clecoed together, the bulkhead on my matched hole kit is so close to the thickness of the wing spar that all I'm going to do is stack a bunch of area washers in there to simulate the thickness of the spar. In your case, you can always insert a shim to make up the .006 difference. Shown is 14 days work into the fuselage kit. I cannot say enough about the wonders of matched hole technology!

errata13115pj3.jpg
errata13215he6.jpg

errata12515fx7.jpg
 
I ended up making the spacer by stacking up 5/16" nuts nuts to slip over the 1/4" bolts, plus a 0.040 spacer to get the thickness I needed. It ended up 0.003" wider than the wing spar thickness. There is enough compliance in the structure to allow that 0.003" to be squeezed together when you torque the bolts.
 
Matched Technology

Geez, Rick, 14 days? You are really cooking.

I suppose that I am not that much slower, except that my 14 days are separated by a whole bunch of work days. I would certainly agree that the pre-punch is simple and aligns really well. The micrometer on your photo tells the whole story.

Your entire interior is green. Is that AZKO primer? I have been priming and top coating the interior parts as I build. I used AZKO for the wings and empennage but didn't think I could top coat over it effectively and switched to Stewart Systems for this part. Am slowly learning how to spray paint. Quite the art-form.

Regards,

Michael Wynn
RV 8 Pre-punch Fuselage
San Ramon CA
 
mlwynn said:
.........Is that AZKO primer? ....
Click to expand...
Mike,

Yes, I really like AKZO. It has a long pot life and dries to the touch within an hour. That stuff has been wiped down repeatedly with MEK in my 6A and has proven to be as tough as nails. I'm told it can be color coated when fully cured without any problems. This time around I primed just the contact surfaces on the empennage and wings but in the end, decided to 100% prime the fuselage. Unlike my previous experiences, I have been mostly using the little spray pistol that uses film canisters...very little waste and minimal clean-up.
 
Back to the original question

Rick,
I had a length of 3/8 threaded rod and a pile of nuts when this stage of assy came up. It was a lot easier to cut 4 short rods and used double nuts to create 4 fixed length "spacers" than it was to go find a planer for a custom wood piece. I adjusted the spacers until the spar centers had the right gap.

I am finished with that step and the spars fit fine (during a test fit after fuselage canoe riveting was complete.)

With this method, I obviously didn't use "legs".

I made a wood plate and attached it to the firewall and then fit a galvanized base flange and a short 3/4" pipe to make a pivot. This fit into a hole in a board bolted to a basement post. The tailcone sat on a saw horse.

I found it nice to have the fuselage upside down while doing the cabin structure on the 7. This may not apply to the 8.
 
I used bolts with nuts and washers Like this guy:

http://users.pandora.be/rv8/Web pages/construction/Fuselage/Images/fuselage_centersection_6.jpg

He used threaded rod . I used bolts (with heads) so I could be certain that I didn't have a twist in the c-section. Remember to put all the AN4 (or whatever they are) tight tolerance bolts to ensure proper alignment.


I am using AKZO and over-coating it. The C-17 has many parts in it that get the AKZO then a bright white epoxy overcoating. I was told by the paint guy at work that as long as you overcoat within 24 hours the topcoat will stick.

If you forget in the 24 hour period, then just scuff primer with a SB pad and wipe with lacquer thinner or acetone before painting
 
Virtually any dimensionally stable material should work. While threaded rod has been used by some builders, I suspect Van and others would wince at the thought of threaded rod through a precision close tolerance hole just on general principle. Bolts are a far more desirable alternative. I'm going to take a slightly different tack. I just ordered a 12" stick of 1-1/4" dia. Delrin rod from Spruce. I plan to cut it into eight equal lengths, drill a .250 hole through the middle of each. Installed with area washers on both ends of the rod contacting the spar should do the trick just fine.
 
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I hear ya, that was my thought too so I used a size smaller bolt and tried to center it in the hole. I will not be attaching legs through the c-section so the bolts will never hold up any weight.
 
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