RV-3 Plans - 'Clarifications'

[Andy Hill]

I have suggested to Paul Dye that we start this thread as a 'sticky'. It is intended as a summary of significant errors / omissions / areas needing clarification in an RV-3(B) build. Paul's seems to like the idea

To keep it separate from the ever expanding "advice" topics, we suspect it will need "moderating" according to a set of rules, which as a first guess might be:

1. Posts titled with the major sub-structure affected, maybe then with the Part #(s) e.g. Flaps - FL-303
2. A brief summary of the "apparent" error, and the suggested "solution"
3. Where possible, expand the above information not in the post, but by links to websites / VAF threads giving further info
4. Replies - additions to the info e.g. follow up later in a build as to whether it worked or not, use the same post 'title', and maybe the replies can be moderated into the original post...

Summary - to be effective the posts must be concise, and not diverge "off topic"

Andy (Hill)
RV-8 G-HILZ
RV-3 SB going slowly

PS I'll kick off with a sample on Flaps...

[Andy Hill]

Root Rib needs moving inboard

Randy's site info from Dan Benua

DWG 9 - Flaps. ... My solution is to move the FL-303 rib inboard by about 7/8". This places the linkage attach point closer to the curve of the fuselage. To achieve this the top flange of the FL-302 lap spar should be dimensioned to 49.5". The lower flange lengh should be 51", which is the length of the supplied material. The rib and FL-305 reinforcing plate should be mounted coincident with the end of the top flange. (N.B. I haven't yet built the fuselage to conclusively prove that this modification is beneficial!)

This seems to fit in with Tony Spicer's experience as per:Used washers to space a coupling nut on the flap stud where a spacer was required, and Without moving the flap arms inboard the pushrod will contact the inboard edge of the flap fairing.Rob Holmes also had some issues Pic

Follow up(s)
[Andy Hill April 2010] We have built the Flaps with FL-303 moved inboard by 7/8". Will update in ? months/years when we fit to the fuselage

[islandmonkey]

I have already have a section of my build site devoted to this. I have collated all of Paul's relevant posts onto this page in my site and I will be updating it as and when an appropriate post or piece of information comes my way. Here is a list of Paul's posts, that fall under your criteria:

Error on Quick Build Wing

Aileron Gap rivet question

F-303 Center Section Build-up

Lower Forward Stringers in the Fuselage

F-336 “Wall Outlet” SNAFU….

Send me a mail if this is okay, and if Paul wants to expand on these topics later I will edit this post out.

[Andy Hill]

Flap parts longer than Plans?

DWG 9 shows a distance of 10 1/2" from the Flap TE to the Hinge CL with reference to the fuselage datum. Trig that to the vertical displacement and you get ~10 19/32" as the length measured directly from TE to the Hinge CL.

Putting the (supplied) FL-302 (Spar) and FL-303 (Outboard Rib) into FL-301 (Skin), and adding the hinge as per Plans gave a distance about 5/32" more'. Paul Dye seems to have come across supporting evidence of this RV-3B - Fiddling with Flaps

With the ailerons mounted per plans, and measuring so, we discovered that the flaps were sticking out close to a quarter inches beyond the ailerons.

Solution(s)? Paul describes how he tackled it in the above link. Being a SB, we could try to tackle it closer to source, and moved the Flap Spar back ~2/32", and trimmed the hinge / skin / positioning and got another 2/32". Assembled the distance is 10 20/32" i.e. we seem to have "removed" 4/32" of the 5/32" error... but will only know when we fit ailerons to the wing.

Request(s) for Info: Can others let me know / post here and I'll edit into this post, this measurement for their Flaps, esp QB ones.

Follow up(s)
[Andy Hill Apr 2010] We have built the Flaps with the direct distance of Flap TE to Hinge CL = 10 20/32". Will update when Flaps/Ailerons/Wings all fitted as to how TEs line up

[danbenua]

I'm not sure what the QB guys are facing, but for a SB wing the
procedure is straight forward. Mount the ailerons first and use
an airfoil template to be sure they are exactly in trail. Build
the flaps next, and drill the hinge to them. You don't have much
flexibility on the distance from the flap spar to trailing edge unless
you modify the shape of the end ribs. Finally, trim the trailing edge
of the lower skin so that the flap and aileron trailing edges are
in line when the other half of the hinge is drilled. The flap brace is f
abricated an mounted after the skin edge is trimmed.

You should considered the dimensions on the plans to be only
advisory. On this airplane, nearly everything is "trim to fit".
You always have to be thinking about which dimensions are
not adjustable, and then adjusting everything else to make
things match.

- Dan Benua

[Ironflight]

When fabricating the rear fuselage deck, I laid out the holes (forward round one, middle "pear-shaped, aft rectangle) per the drawings, and it just didn't look right - the rectangular hole at the back looked too far aft by about an inch. These holes are located on the drawing by measuring incrementally from the front of the deck, and I discovered that the "8 inches" seemed to be the error - it put the pear-shaped and rectangular holes an inch too far back. I laid it out again replacing the "8" with a "7", and everything fit much better.

Treat this as a "potential" plans issue - I'll report further if I have created a new problem by changing the locations.

Paul

[rph142]

When constructing the rear spar of the horizantal stabilizer, pay close attention to the rivet spacing in the area where the fuselage - HS attachment bars will be bolted on. You must leave plenty of space between rivets in order for these bars to sit flush.

When drilling the rivets for the rear deck access plate, pay close attention to the rivet locations in the area that the front horizantal stabalizer angle bracket will be attached. The rivets holding down the rear access plate could interfere with the front spar hold down angle.

[Ironflight]

Quick summary - 48 1/2" worked for me.

The plans leave a lot to be desired when it comes to fabricating the elevator pushrods. The forward one (F-337) that links the stick to the bell crank is shown on Drawing 22 with a cut tube length of 49 1/2 inches "To be determined in assembly". Well, it's good that they warn you, and also that the 49 1/2 inches is extremely generous - it's much easier to trim more off than it is to add it back on.

The exact length is dependent on the final position of the stick mixer assembly and the bellcrank - neither of which positions can be determined from drawings (they are shown but not dimensioned). I centered the bellcrank between the F-306 and F-307 bulkheads and positioned the mixer bearings where they seemed to fall given the mounting angle length. I then cut the pushrod to the specified length and did a test fit. Clearly, it was too long, as the stick and bellcranks were at their full deflection with the rod ends screwed all the way in.

I shortened the tube in small increments, and finally got to the point where the bellcrank was mid-travel with the stick in about the middle of it's range. most importantly, I can get full stick travel and full bellcrank travel. This is still with the rod end bearing screwed almost all the way in. This occurred with the tube cut to 48 1/2" - one inch shorter than specified. Seems like a large deviation, but I can always screw the rod ends back out to get almost an inch back if I need it later.

I couldn't find anything in the instructions or drawing that give rigging instructions, so I am going with the idea of mid-range for the stick should be mid-range for the bellcrank, We'll see if that works when I mount the elevator.

Paul

[Andy Hill]

DWG 9 details the Wingwalk reinforcement, and states sheet required 10"x24". Also states "Left Wing only".

Kit provides a sheet 10"x48"... and you might be forgiven for thinking they gave you enough for 2 e.g. in case you built a slider canopy and wanted one RHS as well.

Unless I have got it wrong I found the sheet required to be trimmed to ~9.5" x ~25" - so suggest do not cut the sheet in half / to the stated dimensions - carefully measure the ribs/spars and cut/trim accordingly (pretty good advice for the RV-3 all round )

Andy

[Andy Hill]

Not an "error", but definitely a well laid trap

The Build Manual and the main Rudder drawing all seem clear - bottom rib rivets to Rudder skin, been there, done that a few times before. So we'll drill, dimple, prime and rivet.

Before doing this, I had a think ahead - how do we attach the Fibreglass Rudder bottom? Study drawing, takes me to Section E-E, look at that, and lo and behold, see it requires a ~1" wide strip of 0.032" to be riveted with the above on the inside of the rib.

Looking at the RV-3 build websites, and some "completed" rudders, not much evidence seen of these strips So presumably some rebuilds going on at the end as the tips get fitted

Andy