plans measurement question-

[fairchild1934]

I asked this in the sub-forum-- but no one has piped up with an answer so far----- so I thought I'd throw it out here for maybe wider visibility.
I'm hoping to not have to call Bob and ask because i'm sure he has plenty to do every day.

Trying to determine the proper location of the rudder rib that overhangs the rudder spar point forward (where the counterweight goes)
The front tip is known from an X and Y measurement called out on the plans. But I can find no way to pin down where the rear end goes--- where it welds to the main post. Tried using a scale ruler on the plans and also measuring the angle of the rib--- but I get different numbers.

Can anyone tell me how to ping that location down ?

kind of stuck in the mud till I can figure that out.

Tim

[geraldmorrissey]

Do not fail to call Bob if you do not get a satisfactory answer here. Your a plans holder. He will make time to talk to you. I have called a few times and if Bob is not available, he calls back.

[fairchild1934]

I will ring him tomorrow if I don't get something that makes sense ! :-)
Thanks

[alaskabearhawk]

Bob drew the plans to scale and as such expects the builder to use those measurements in the construction of the components. That is, assuming of course, the EAB builder wants to follow them! I know the plans are printed using special printers that do not alter the scale. So, using angles and other geometry calculations to determine dimensions should be secondary to a direct measurement off the plans using an engineers ruler. At least that’s how I look at it.

[fairchild1934]

Yes----- I did a direct measurement two different ways-----

Measured down from the tip with a scale ruler---- got 9.0 inches
Measured the angle the rib makes with the post-- and projected that from the forward corner of the counterbalance section-- got 9+ 5/8 inches
(and the angle of the rib measured 110.3 degrees to the post---- to get the 9+5/8 )

not sure which is correct---- (if either--)


Tim

[ScottS]

What I did on mine is build the hinge on the bottom which is locked in place, bolt it to the fuselage and there should be 3/8 of an inch between the two ribs on top, 702E19E2-F299-4BF0-9192-76A18E5BEF52.jpg what ever is left sticking up is what it is, the rudder post has a specific length. Scott

[fairchild1934]

What do you mean--- "whatever is sticking up " ........

FYI--- I don't have a fuselage yet--- the rudder is the first part of it I am building. :-) I thought the tail feathers would be good to warm up on-- until I get the main load of tubing in.

[fairchild1934]

OK --- here is what I did----
I had not coped the top of the rudder post yet. So I coped that- and fit a piece of scrap 5/8 onto it -- and used the top of that 5/8 tube to measure from.
After doing that ---- now I have a measurement from that top point of 9 inches and 9+1/8 inches. (by the 2 methods) So throwing in the top piece of scrap seemed to converge my two measurements quite a bit. So it appears to be 9 inches down from the top to the center of the rib where it welds on to the post. Do yall think that is close enough ?

Tim

[DBeaulieu]

fairchild1934 Tim, I have a Patrol QB rudder which is uncovered. If I can be certain of which measurement you want to obtain/confirm, can I help somehow?

Dave (from Maine)

[fairchild1934]

Oh yes DB------- I'm looking for the measurement from the very top of the rudder (where the 5/8 and 3/8 tubes meet the post) down to where the counterbalance rib welds to the post. (maybe to where the lower edge of the rib meets the post -where the weld bead would be-- in that angled corner--)

I am getting either 9.0 inches or 9+1/8 inches---- (see the green arrow on the pic )

Thanks ahead of time !!!!!! I'm stalled until I can be sure that's in the right place. :-)


image.png

rudderdiagram.png image.png

[DBeaulieu]

fairchild1934 Here you go...I measure 8 11/16" NOTE the scale ruler is at the 1" index to start off the measure
rudder 1.jpg rudder 3.jpg rudder 2.jpg

[geraldmorrissey]

Could uou include a couple of pictures of the intersection of the elevator ribs and the 3/8" elevator trailing edge tube. Thanks

[fairchild1934]

Thanks DB------ I see the gap between the rudder rib and stab is about 1/2 inch----- I think someone here said it should be 3/8 inch. If that was shrunk
just a dab--- that would bring the measurement to about 9.0. Wonder if the factory leaves that gap a little big to have to alleviate the tolerances.

so somewhere between 8+13/16 and 9.0 should work I would think. Thank you so much for the measurement ! That verifies I am in the ball park----

Tim

[fairchild1934]

OK----- Thanks DB----- for the measurement--------
would you have any means to check the angle of the rib from the post ?
(just as a 2-nd backup means to the measurement---)

[DBeaulieu]

Should be able to do that today...standby