Wing tanks
 

When we did CN-2, we drilled out and un-skinned the wings from the ailerons up to the spar, all the work is done at the root rib and the back of the spar. So no, you would not be able to do the wing tanks unless you did considerably more deconstruction to the wings.
Dave

Probably more of an anecdote than helpful information. But because of having the lower inboard skin peeled back for the CN-2 mod, I decided to make truly integral wing tanks. Using epoxy, I closed out the lightening holes in the outside LE ribs with round plates and pop rivets. Then coated the inside of the front bays with "angel hair" fiberglass cloth and epoxy. Installed filler neck, vent line and homemade capacitive fuel sender (tube within tube) from inboard bottom to outboard top). Then closed the lightening holes in the spar web with round plates, epoxy and pop rivets. Finally installed cover/access plates over inboard rib lightening holes. No lower skin stiffeners as the wing tanks were for long range use only -- I would normally only fly with the 25 gal fuselage tank. Months of work. I did get the tanks leak free -- for a while. I guess the repeated heating/cooling by the Florida sun of the epoxy and aluminum caused separation or cracking of the epoxy.

Perhaps would have been more lasting with just proseal -- if possible to get all joints clean enough. And, with help, you could install lower skin stiffeners.

Finn

I am in the process now of doing the CN-1 and CN-2 mods to an old RV-3 kit. I would be very interested in seeing any pictures you may still have of your mod. Can they be posted or could you provide a link to where I might see them. Did yours have they Type I spar caps or Type II?

Thanks,

Bob Anderson

Mycool, Did you get your mods completed? If so, any tips you can pass along?

Bob Anderson

Spar Mods RV-3
 

I did complete my spar mods. I have lots of pictures, but would need to compile them in one location and then figure out how to give access to them.
I will see if I can figure something out. Send me a PM and I can discuss.
Dave

RV-3 Spar Mods
 

Dave,

Did you have the Type I wings or Type II? Also, did you have to change the configuration on your wing rear spar attachments? Any special technique used for drilling out all of those main spar cap rivets?

Thanks,
Bob

My main spar rivets were 1/8".
So didn't require high precision drilling because the new rivets called for are 3/16". (Just ensure adequate edge distance.)

I got a 7.5 pound chunk of tool steel I used as bucking bar. I was able to set the new rivets with my 3x gun.

However, if you anticipate setting the rivets being a problem, you could carefully ream the holes to tight fitting AN3 bolts (NAS if needed). Bolts are allowed per the change notices. Of course they will be heavier than rivets.

I've looked for pictures but it appears the only ones I have are on a VHS cassette (low resolution).

Finn

Spar Upgrade
 

My wings were type I, but the builder made the plane a year or 2 after the first couple failures which were attributed mostly to poor edge distance and builder technique. None the less, the wings were later tested and found to not quite meet the requirement so...the Change Notice.
Anyway, knowing of the failures, some upgrades were incorporated into my build which made it stronger, but did not meet the CN-1/CN-2 explicitly. So we had to work with engineers at the factory to make new details based on what we had. There were some extra straps and things we had to work around.
Now I have CN-1 and CN-2 completed, we did not need to change the spar attach, we had plenty of edge distance and the carry-through met the requirement. Like I said, mine was not typical.
Already mentioned, rivets were not precision drill due to using 3/16 going back in.
Dave

RV-3 Spar Mods
 

Thanks Finnflyer and Dacronwall. The idea for the a heavier bucking bar than normal sounds like a good idea. Did you back rivet the 3/16" rivets or squeeze the gun into the leading edge? Any other advice you think of feel free to pass along.
Thanks again - Bob (Chillibob)

If I remember correctly. I rested the bucking bar on a rag or foam on the leading edge skin and had the rivet gun on the rear side of the spar. I may have been resting the gun on something too, to help prevent it from wandering away from the rivet head. I short full trigger bursts too to make sure rivet set didn't wander off of the head.

Oh, and I had the wing positioned at a height so I could stand with arms and hands at maximum strength holding bar and gun. I think working position will be the key to setting the rivets. Do have the trailing skin peeled back enough to give you good access. Drilling out a few extra skin rivet will pay off.

It's very possible you could use a pneumatic rivet squeezer instead. Don't know if Van's still rent them. I think that was my plan B in case I had trouble with using the rivet gun.

Finn