RV-3 Questions

[spyglasss]

im starting a project to get a previously flying rv3 back in the air
is it possible to use a dynafocal mount in the 3?
i don't have a preferance over the conical, but
have a line on good 0-320A which may have the
dynafocal mount does anyone know? I am not a real engine savvy guy
any info would be appreciated.
the spar mod was completed and logged in the 90's,
has anything changed along those lines?
also, will the standard (heavy) starter fit in the 3 cowl?
Thanks!
Dan

 

[Mike S]

Welcome to VAF!!!!

Dan, welcome aboard the good ship VAF

Good to have you here, enjoy!

 

[danbenua]

Hi Dan,
Van's sells a dynafocal mount for the RV-3. Depending
on the vintage and original builder of your plane, there could
be some isssues with alignment of the attach bolt holes
in the firewall and the corresponding holes in a new mount.
Mis-alignment is fixable, but may require some surgery
on either the mount or the firewall.

You should have no problem fitting an old-style (heavy)
starter in the cowl that Van's currently sells. If you are
planning to use an old cowl, some adjustments will
probably be necessary to fit a different engine anyway.
You might consider switching to a more modern light-weight
starter. In a small plane like the RV-3, every pound counts!

Details on the spar mods (there were two) and links to the service
bulletins are found on Randy Lervold's site here:
http://www.romeolima.com/RV3hq/Info/info.html
You definitely should study them carefully and inspect the
wings to be sure the mods were done correctly. Don't rely
completely on the logs.

Good luck with your project!

- Dan Benua
Tech Counselor & repeat offender

 

[nomocom]

spar and starter

the spar mod was completed and logged in the 90's,
has anything changed along those lines?
also, will the standard (heavy) starter fit in the 3 cowl?
Thanks!
Dan

Dan, welcome to Vansairforce.

The front spar mod (CN-2-_) has a file date of Feb. 97, so what you may find is the first mod has been completed (CN-1-_), but the second, probably less likely. For instance, on N2232B the first mod was incorporated into the original build (1990 completion), but the second mod was still many years from publication as the original build was wrapped up. So briefly then, the question a non-B rv-3 buyer/owner asks is not, is it a 3 or 3a, but has it had both CN-1-_ and CN-2-_ completed.

N2232B is fitted with a 16.5 lb starter (0-320) and while there is an alternator bump on the cowl, there is no such bump on the starter side. Even though there are many good lightweight starters, my heavy starter will likely stay for W&B reasons.

 

[sandifer]

I will echo the comment about potential misalignment associated with the firewall holes for the mount. Measure the existing holes and compare with the plans. If the original builder made his own mount, it might not be perfect. Happened to me. I needed a custom mount built to match the holes in mine. RV mounts are so stiff, you have no wiggle room on the mount itself. If your holes are within a small fraction of an inch, call Vans to get their opinion on slightly enlarged holes to accommodate small misalignment.

 

[spyglasss]

Dan

Gentlemen:
It turns out the engine is a conical type mount, so I wasted a question there.
I will have a great deal of due diligence to determine the spar mod status.
It may be that only the first mod was done. I really hope this doesn't drive
a stake through the project!! Can I perform the second mod now? Would it
require a huge teardown? I will try to find an EAA tech guy in the area, (St.
George, UT) to help me look at the spar/root ribs. The "unofficial" rv-3 website is priceless!! I am reading every word. Any of you guys have a steak dinner
and a bunk waiting for you in Ramona, CA. (KRNM, 25 NE of San Diego.)
THANK YOU!!!!!!!
Dan

 

[sandifer]

It may be that only the first mod was done. I really hope this doesn't drive
a stake through the project!! Can I perform the second mod now? Would it
require a huge teardown?

Dan,

Do you feel you NEED to do both mods? What is your flying mission with the airplane? Does it include aerobatics? Are you currently an experienced aerobatic pilot? I had an RV-3A (CN-2 not performed) for five years and never worried about the integrity of the airplane. I obeyed the 4.4G recommended G limit. Vans will tell you there's nothing wrong with the original wing design as long as the airplane is not overstressed. Destructive testing found evidence that the margin over 6G was less than the standard 50% that most aerobatic designs can sustain before catastrophic failure. This is the reason for the mods. I've read the accident reports associated with RV-3 wing failures, and they're mostly overstress and stupidity.

Also, are you an experienced builder? Do you feel you could do the mod precisely? If you are not an experienced aerobatic pilot and feel you want to do aerobatics with the plane, then it would be best to do the mod. I am not encouraging going against the Vans recommendation for not doing aerobatics without both mods performed, but the reality is that the basic aerobatic maneuvers can easily be done by an experienced pilot perfectly consistently at no more than 3-3.5G. Like any other aspect of flying, safety is up to the pilot, not the airplane. There's nothing magical about 6G (+50% margin). It's just that the less the margin, the less room for error. The margin you need depends on your abilities and everyone must make this judgment for themselves.