N

New Eight Guy

Member
Greetings Gents. I'm working on the horizontal stabilizer and to the point where I can remove the skins and clecos and start riveting ribs. A couple of friends of mine who have both built RV4's noticed the rivet spacing on the rear spar close to the but joint and said (quite adimately)I should add approximately 6 inches of half spaced countersunk rivets in this area.That would mean a spacing of 5/8in.Apparently they saw some RV's that showed some smoking around the rivets in this area and this was the fix. Both their planes have this rivet amendment and there are no problems evident after hundreds of hours.Do the RV8 and RV4 share the same basic tail structure? Is this something I should address? I'm new to this type of construction ( I have restored and am flying an Aeronca L-16A)...these guys have agreed to look over my shoulder when needed etc and I don't want to offend them. Any help would be appreciated.Mark.S.
 
I agree with Rick - you need to listen to the guy(s) who designed this particular airplane (and wrote the plans, and made the kit...), rather than folks that built something else - unless, of course, they are aircraft structural designers themselves, and can show you the calculations that prove their idea is better.

There are hundreds of RV-8's flying without the tails coming off. Adding structure doesn't always make things stronger, and adding holes for additional fasteners can make things weaker.

If your friends don't understand these simple facts, than I certainly wouldn't be listening to to their building ideas.

Paul
 
Dimple them

If rivets are showing signs of loosening (ie: smoking) then I would advise dimpling those holes versus machine c-sinking them. This does not violate any build-intent from Vans nor does it violate AC43.13. Machine c-sinking in .032 skins will "knife edge" the inside edge of the hole, reducing bearing surface against the rivet shank. Although this practice is acceptable, I think a dimpled installation would be stronger.

FYI: minimum spacing for a single row of rivets is 3X diameter, measured from center to center of each rivet. Reference AC43.13-1B section 4-57 "Riveting".
 
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