RV6 vertical fin and rudder on RV4???

Stewbronco · #1 11-01-2019, 01:56 AM

Hi .. recently bought an RV4 with .016 skins on rudder and an electric rudder trim tab built in . Have some of what seems to be common skin cracks . K
Just bought a kit for RV4 Vertical fin and rudder with .020 skins BUT locally two RV6 Vertical fins and Rudders have become available by a couple of very well respected fellows . They ended up buying after completing the tail kits . So got together with another local RV6 owner and looked at plans and looks like most if not all parts in 6 Vertical fin and rudder are RV4 .
So would the RV6 Vertical fin and rudder fit on the RV4 and save me a build ?? Many thanks. Stew

smokyray · #2 11-01-2019, 07:59 AM

Quote:

Originally Posted by Stewbronco

So would the RV6 Vertical fin and rudder fit on the RV4 and save me a build ?? Many thanks. Stew

Short answer, yes.
The RV4 and 6 VS and HS will mix and match, but require the corresponding Elev and Rudder as well. My RV6X actually has RV4 wings and tail(VS/HS) mated to a Six fuselage and flies great.
Realize the 6 VS and HS are slightly larger but attach points are the same. Once you decide, you have to match the Elevator and Rudder to the specific HS and VS.
As they say in Jamaica, No problem Mon...

V/R
Smokey

Sam Buchanan · #3 11-01-2019, 08:29 AM

New weight and balance calculations are highly recommended.

rvbuilder2002 · #4 11-01-2019, 11:05 AM

Putting an RV-6 horizontal stab. on an RV-4 (or vice versa) would likely have some fit issues because the tapper angle of the fuselage tail cone is different, so the root ribs on the stabilators are in different locations. This results in the center portions of the fwd spar being different widths which will effect fastener placement and/or overhang on the fuselage so that there are no interference's or gaps.

I agree that the vertical stab and rudder could be made to fit an RV-4.

cardinalflier · #5 11-01-2019, 06:49 PM

Email sent to Stew

Stewbronco · #6 11-01-2019, 06:59 PM

Hi ... did not get an email ? stewhansen@shaw.ca Thanks to all for responses. Cheers. Stew

Bob Martin · #7 11-04-2019, 06:33 AM

Quote:

Originally Posted by Stewbronco

Hi .. recently bought an RV4 with .016 skins on rudder and an electric rudder trim tab built in . Have some of what seems to be common skin cracks . K
Many thanks. Stew

I will add to look closer for the source of the rudder cracks. Sometimes the VS is not installed with the 3 attach points lined up. But the attach hardware is adjusted to bolt up. Then when the rudder is deflected, it twists the structure of the rudder and causes the cracks in the rudder skin. If you replace the VS you will address the straightness but if you just replace the rudder, be careful to check the existing VS. Just an FYI.

JonJay · #8 11-04-2019, 09:30 AM

To add to Bob?s excellent suggestions, you can search for Rudder Cracks in the forums and get a boat load of discussion.
Most cracks in .016 skins are caused by improper construction, usually under formed training edges. Many of us are flying with hundreds and even thousands of hours on .016 surfaces with no cracks.
Regardless of skin thickness, before you bolt another rudder on, you will want to check to insure the skins are not preloaded due to poor construction technique.

Stewbronco · #9 11-04-2019, 08:42 PM

Thanks Guys ... all great advice... I had been warned of the possibility of misalignment and intend to use a laser to check before deciding on new or existing VS .... rudder is going to be new regardless as I do want the .020 skins ( will be sure and try and elevate any built in stress) and current one has a built in tab that I want to eliminate . Appreciate the advise. Stew