Rottisserie questions (tail end)

[Pbruce]

1F84F181-18A6-4D12-97CE-E5127C613BC7.jpeg I built a rottisserie out of engine stands. Used in on the wings. I put universal joints on both stands. Worked pretty good, but had some issues with the wing “flopping” due to its weight, until the limit of tension was reached. I now wish to mount the fuselage on the rotisserie. The firewall mount seems pretty well documented by most guys and similar construction used. Harder to see what others did at the tail end though.

There are 3/16 holes for the flying wires on the rudder-mount post, top and bottom. Could I suspend the fuse from tabs bolted through those holes? Would that risk bending the post when the fuselage is sideways? The other obvious mounting spot is the stabilizer carry-through tube. It’s strong enough, but doesn’t lend much support near the top of the fin either. Stinger tube doesn’t help top end at all.

Looking for suggestions. Picture shows what I’ve been using for wings. I don’t weld, so I depend on friends and cash at welding shops so it needs to be simple.

[TimTall]

I don't have pictures right now but i used the rudder hinge holes on the tail post for the rear rotisserie.

[robcaldwell]

I did the same.

[Pbruce]

One top one bottom on the B? That’s what my patrol has. Did you have concerns with the fin flexing sideways when the fuselage was rotated over onto its side?

[alaskabearhawk]

I just used the tailwheel mounts. I figure it was the strongest point back there and it's aligned with the plans centerline.

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[svyolo]

I used a piece of the 1X2 steel pipe from wing crate. To one side I thru drilled both sides and welded the U-joint to it. The other side I thru drilled (at an angle to fit into the tailwheel tube) and put a piece of heavy round steel tube into the tailwheel tube. Welded it to both sides of the 1X2. Put some scrap 1/8" steel straps up top to capture the upper rudder hinge bolt.

The middle of the U-joint is 7.5 inches from the top of the rudder tube opening.Balance is OK, takes about 20 lbs to hold it horizontal by hand.An inch higher might be better. I have a B model.

[Pbruce]

Just to clarify: U-joint is 7.5” below the top rudder hinge hole? That would place it more than halfway up the fin? The hole we are talking about is the one which goes side to side through the fin post? And you say it should ideally be higher? Like 6.5” below? Is your front pivot in line with the top engine bolt holes, or did you displace it downward? If so, how much? Thanks

[svyolo]

I will measure mine tomorrow. On my B model, the U joint is 7.5 inches above the upper edge of the tailwheel tube. I would go up 1 inch next time.

[Pbruce]

Ok. That makes sense to me. Thanks. Probably close enough. How about the front pivot location; is it between the top engine mount bolt holes, or is it lower?

[svyolo]

Yeah mine are between the left and right upper bolts.

[robcaldwell]

Lower the V stab so it doesn't hit the floor when you roll inverted.

[Pbruce]

Ok with that in mind I’m taking a wild guess that if I raise the u-joint pivot point on the tail to about 9.5” from the bottom rudder hinge hole, and then lower the front u-joint pivot point to about 3” below the top engine mounting bolts, it might balance.

[robcaldwell]

I made my engine stands adjustable up and down, but I did not measure. Just made adjustments after installing the front and rear until it balanced. I don't recall that it took much to get it right.