RV-6A false spar after wings removed?

[GJHeck]

I'm installing my gear weld mounts and would like some ideas of what others have done after they take the wings off and the airplane is resting on the gear? Do you need a false spar or can you just leave it with out the wings on and add weight (engine or someone sitting inside)?

 

[664781]

I used a false spar, not much suppoprt with out it.

 

[trib]

You definitely need a false spar. The gear leg supports bolted to the fuselage sides alone will be very flimsy and practically certain to damage the fuselage sides with an engine mounted or someone in the cockpit. To make a false spar, simply purchase a piece of 1"x8" board, 6 feet long or longer from your local Home Depot. Then look in the specialty board area and get a piece of 1/2" thick (actual dimension) fir board, 4" x 4' nominal size. You cut this and glue it to the 1"x8" material where the gear mounts bolt up to the false spar. The actual thickness of the spar will be 1 1/4" where the gear mounts attach (3/4" + 1/2"). Use guide bushings (I used some cut from steel auto brake lines) to drill thru your spar holes into the false spar. You only need a few bolts on the top and bottom, not necessarily every hole.

I extended mine about 6" outside of the fuselage on either side. That way, I would bolt up a length of 2"x4" to the extension which went straight down to the floor and act as legs to support the fuselage with the gear removed.

 

[ChiefPilot]

When you make the false spar, don't forget to cut a relief on the bulkhead side for the nut plates used to secure the removable floor rib (provided you've installed those already).

 

[recapen]

I have a set of these that I used....they've also been used by a number of other builders.

Absolutely needed!

Contact me direct if you want to see pictures.....

recapen at earthlink dot net

 

[ArVeeNiner]

Dohhhh!

Uh oh. I've had my 9A on the gear for over a year and now with an engine for about two months without fake spars. I never thought about the lack of support but it makes sense. I haven't noticed any damage but I haven't really looked that close either. I'll check it out tonight and then put some fake spars in there.

I'd think the purpose of the false spars is to allow the rear half of the main spar to share the load right?

 

[L.Adamson]

Uh oh. I've had my 9A on the gear for over a year and now with an engine for about two months without fake spars. I never thought about the lack of support but it makes sense. I haven't noticed any damage but I haven't really looked that close either. I'll check it out tonight and then put some fake spars in there.

I'd think the purpose of the false spars is to allow the rear half of the main spar to share the load right.

The "9A" structure is different than the 6A, since the "6A" spars carry all the way through, and butt up against each other. So while the 6 has nothing but a bulkhead without the spars or fake spars, at least the 9 has something. But it's been a while since I've looked at the 9's structure.

L.Adamson --- RV6A

 

[ArVeeNiner]

The "9A" structure is different than the 6A, since the "6A" spars carry all the way through, and butt up against each other. So while the 6 has nothing but a bulkhead without the spars or fake spars, at least the 9 has something. But it's been a while since I've looked at the 9's structure.

L.Adamson --- RV6A

Thanks. I checked it out last night and it looks like it's not going anywhere without the false spar. The gear bracket has an arm that extends forward and attaches to the side of the fuselage keeping any tendency to twist in check. Plus, I have a couple of bolts and spacers installed at the top of the carry through spar which helps keep everything stable.

So, it looks like this isn't a concern for a 9A.

 

[GJHeck]

Thanks Tim for the detailed response........especially the guide bushings. Hope to install the wings this week.