www.rv3works.com

Since there are many RV builder's sites out there documenting airframe construction (check the links page at Van's Aircraft), this site won't do that. Rather it will attempt to point out any unusual aspects of each phase of construction, and especially anything I might come up with that I think would benefit other builders. As one who has built one of Van's newer kits, an RV-8, I'll especially point out any significant difference in what is supplied for those interested in tackling an RV-3. Otherwise, as Van's says, "just build it to the plans".

Airframe construction begins...
Immediately upon starting construction I could tell that this kit was a different ball game than the RV-8, or any of the prepunched models. The difference really is that even with the partially prepunched kits, where the skin only is prepunched, there is an absolute reference to use in making sure the final assembly comes out correctly dimensioned and straight. With no computer prepunching you must create your own reference by measuring both the frame and the skin, in other words it's all variable. Ken Scott at Van's says "think from the skin in, build from the frame out". Fine, but this only works with skin prepunching. Not having a known reference raises the stress level, not to mention the workload because you don't want to drill a hole or make a cut in the wrong place.

Prior to starting the project I was told by many (including Van's!) that there are occasional errors in the manual and plans. Yes, I've found quite a few, but if you're a second time builder they are fairly easy to spot and work around. Some of the errors are really parts reference errors where the manual describes a part inaccurately since it's been superceded at some point over the years with an RV-4 part and the manual/plans weren't updated. This is not that much of a problem. Then sometimes the manual describes fabricating a part that is now already made for you, a pleasant surprise but there aren't very many of these. The omissions however are the most challenging. The drawings are not as detailed as the newer kits and may not show how parts fit together. This requires the builder to guess, or by extrapolating from knows data points, which isn't always possible. It makes the building process a significant mental workout and very challenging. Again, this is mitigated if you've built any RV already because you have a pretty good idea what to expect. Bottom line, laying out the rivet lines is not the most time consuming part, the increased level of part trimming and fabrication is. After a while, you get used to it however, and the fact that it's a physically smaller aircraft with an accordingly lower parts count works in the builder's favor. Second time builders won't have too much problem, a first time builder would. If you are thinking of building an RV-3 consider all this and my other comments here.

One topic of endless debate among aluminum airplane builders is primer. There are literally thousands of comments on various primers in the online forums. After all these years of listening to this debate, studying the various materials, and observing the protection offered by the primers I used on my RV-8, I will be using the materials listed in the table on this aircraft. My experience has shown that these products are effective on each of their respective material types, and importantly, they represent a good balance between the time investment in applying the coating and the protection they afford.

Steel parts clearly need some more aggressive form of protection, and the exterior primer will largely be a function of what paint system you or your painter end up using and is typically applied after construction anyway. This leaves the airframe interior. As the builder assembles the airframe he/she must make a decision about what to apply as this will likely be the final coating on most of the airframe's interior parts. Interior primer is therefore what there is so much debate about.

In deciding on the SEM for interior use I did consider the more thorough processes such as acid etch, alodine, and epoxy primer. In the end however, I decided that the materials listed above represent the best balance between the time investment and the protection they afford. Regarding self-etching primers, I did informal testing with most of the commonly available self-etching rattle cans (Sherwin Williams, Marhyde, etc.) and found the SEM to be at least as durable as any of them, but left a nicer finish. Other builders who've looked at the interior of this plane really like the finish as well.

Application
Regarding the SEM interior primer, I use the bulk product with my cheap HVLP spray gun for the larger parts such as the the skins and major bulkheads, and the rattle can version for all the small parts. Being able to shoot small parts as you need to assemble them can really help your productivity. Even though this is an acid-etching primer, you still must prep the surface for proper adhesion. The method I use is to scour all surfaces of each part thoroughly with a Scotchbrite pad and Coleman fuel (naphtha) followed by a wipe-down with a clean towel slightly wetted in clean naphtha. This gives the primer both "tooth" for mechanical adhesion, and a fresh pure aluminum surface for good chemical adhesion. That's why you should prep soon before you prime so the aluminum doesn't have a chance to oxidize preventing good chemical adhesion. Any of the major paint company's degreaser solvents should work fine here also, they're just three times the price of Coleman fuel.

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Notes from empennage construction...

Cracking in .016" rudder & elevator skins
All RV-3s, RV-4s, and early RV-6s have rudder and elevator skins of .016" aluminum. Many builders have reported cracks developing in the rudder skins of their flying planes. The cracks seem to develop in two places. One, at either end of the stiffeners, propagating from the end rivet holes. Two, from the skin/spar joint, again propagating from the rivet holes both forward and aft. Owners are coping with this by stop-drilling the cracks and in some cases building new rudders. Some are using thicker skins, but of course that increases weight. Rather than using .020" or .025" skins and increasing weight, and based on talking at length with Van himself, as well as speaking with many builders of .016 skin parts with hundreds of hours and no cracking, I am sticking with the light weight .016 but employing the following measures...
Build the part correctly:
• Adequately bend the trailing edge - inadequate/incomplete trailing edge bends create stress around the ends of the stiffeners.
• Adequately bend the leading edge forward of the spar - the leading edges should form together with little or no tension.
Add strength and vibration damping:
• Put a layer of ProSeal between the entire length of the stiffener and the skin.
• Put a layer of ProSeal in the joint between the rudder spar and the skin.
• Put the prescribed glob of non-acidic RTV in the trailing edge where each set of stiffeners come together.
These measures should serve to both damp vibration and hold the pieces together better thus not allowing any relative motion between the skin, the spar or stiffener, and the rivet. First off, all of the parts should go together bent so as to not be under any tension. Couple this with the addition of the ProSeal to both add strength and absorb vibration and the RTV and the rudder & elevators should live a long and happy life.

Elevator trim
When building my left elevator I realized the Van's supplied trim cable required a 7/16" hole in the rear spar of the horizontal stabilizer. That creates a problem because the spar reinforcement bars are only about 1/4" apart and the 7/16" hole would require cutting into the bars thereby compromising the strength of the horizontal stabilizer rear spar. I wasn't comfortable with that so after much head scratching I decided to put electric trim in even though I really prefer to fly with a vernier adjusted cable system.
I came up with several electric trim installation scenarios, but the one that I finally went with uses the standard Ray Allen Company servo (T3-12A) where the servo is mounted not in the elevator, but on the aft fuselage deck in the area where the HS and VS meet. Because the RV-3 elevators are not balanced like the later models, I didn't think adding the weight of the servo and related hardware in the elevator itself was a good idea. Also, there is no provision for the servo as there is in all the later models.
In my design I'm using the servo to operate the elevator trim tab via a small cable (ACS #05-16936, A-950 push-pull cable with the end cut off) that penetrates the HS rear spar and then the front of the left elevator. I will use a Ray Allen Company G-305 stick grip with the trim buttons on the top of the stick. This solution has the added benefit of getting one more thing (manual trim mechanism) out of the cockpit thus freeing up that space for something else. I investigated quite a few other methods with more hardware but in the end used simple adel clamps to secure both ends... simple, light, and effective.
BTW, I initially had a servo speed controller installed but after flying the plane I found I didn't need it and removed it.

Rudder trim tab
Most RVs will end needing a small amount of rudder trim. Experimenting with small wedges of wood or plastic and them gluing them on to the rudder is probably the traditional method, but that doesn't allow one to change the setting. Therefore I used the same method on this plane I used on my RV-8: a bendable .020" aluminum trim tab. This may not be considered the most aesthetically pleasing method but it works perfectly. Just bend the tab until the slip/skid ball is dead center at your most common cruise speed. Of course there's only one point at which it will be perfect, but that's what rudder pedals are for the rest of the time. I guessed at a small initial bend and it ended up being perfect, haven't touched it since.

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Notes from wing construction...

I opted for the quickbuild 3B wings — the incremental cost versus the time saved combined with the excellent workmanship seemed like an good value to me. I ordered them immediately upon starting the project because A) the lead time can be significant, and B) I wanted to make sure I knew the front to rear spar distance for fuselage construction by actually having the wings here when the fuselage was built. They didn't arrive until after I'd started the fuselage so I just kept going on the fuselage and finish kit items before circling back to finish the wings.

A pleasant surprise
Several months after receiving my wings while moving them out of my storage loft to begin work on them I noticed something... they have one piece top skins. Wow! All other RV models use two skins to span the top of the wing aft of the spar resulting in an overlapping seam mid-span. Not a big deal, and usually not too visible, but a fair number of RV builders over the years have gone to the extra trouble of replacing these two skins with one long skin thereby eliminating the seam. A quick check of the builder's manual and plans reveals that this is standard on all 3B wings.

A not so pleasant surprise
Upon taking a look at my QB wings I noticed an anomaly. As received, the outboard top skins and rear spars are too long. Interestingly, the rear spar is exactly 1" too long while the top skin is 1/2" too long. They clearly need to be trimmed which means drilling out some rivets, trimming the rear spar and top skin, and replacing the outboard row of AN470 rivets with AN-426 so the aileron bracket can lay flush on the doubler. After pointing this out to Van's they did some digging and it turns out the spar was left long on purpose for jigging during the QB process. As of March '06 they are going to amend the process so the spar gets trimmed before riveting and change to the correct rivets on the doublers. All told this wasn't a big deal to fix.

Bottom skin overlap joint
While the top skin is one piece, the bottom skins overlap in the center as with all other RV designs. They overlap on top of a rib with a single row of rivets however as opposed to the double row on the newer designs. This overlap joint is a potential gotcha — make sure you position the skins carefully to maintain the requisite 1/4" edge distance (center of hole to edge of skin). You might have to fudge the inner skin outboard a bit so it sits a bit short on the root rib, but it can be made to work. Also note on the drawing 9 that the rivet spacing is tighter on the joint line, 5/8" instead of 1 1/4" as for the other ribs.
UPDATE Jan '09: I'm told that Van's is now shipping a longer bottom skin thereby solving this issue. The plans are probably still incorrect.

Front/rear spar distance
See the note below in the Fuselage section about having the wings there when you build the fuselage so you know the EXACT dimension between front and rear spars, this is important.

Fuel tank sender covers
Be advised that the sender covers are not provided with the kit, at least I can't find 'em, and are not the same size as those used on the other prepunched wing models.Therefore you'll have to make your own. More difficult than making the round covers is somehow getting the holes drilled accurately to match the platenuts already in the wing. I used backdrill markers (screws with a pointed head) to mark the location of the holes. I used Proseal and no gaskets to seal both the inspection covers and the fuel senders themselves. I'm not sure Van's even has cork gaskets for these smaller sizes, and they leak eventually anyway. Of course I incorporated both the fuel pickup anti-rotation mod and complied with the fuel pickup locknut Mandatory Service Bulletin by safetywiring the locknut.

Parts substitutions
In the interest of speeding construction here are a couple of ways you can use newer parts from the RV-7/8 wing...
• Use a W-822PP instead of fabricating your own W-335 inspection hole cover. It is slightly longer in the fore/aft dimension so be sure and allow for then as you fabricate the W-335A reinforcement plate and make the cutout in the wing skin.
• Substitute a W-824 RV-7/8 aileron gap fairing for the supplied W-424. This doesn't save any fabrication time but DOES ease installation significantly. The W-424 design is very difficult to rivet onto a QB wing whereas the W-824 design makes all rivet lines readily accessible.
• Use flap fairings from the RV-8 (p/n F-872CPP-L and F-872CPP-R), which are fully formed, rather than the supplied parts. The RV-8 fairings feature an angle that the flap comes up and nests. The whole assembly is cleaner looking, less work, and easier to install, what's not to like?

Flap/fuse interface pics

Flap/fuselage interface
Often times the bottom of the flap doesn't line up flush with the bottom of the fuselage so this can be a place builders struggle to know what to do. As noted above I used RV-8 flap fairings which made things a bit easier. On the right are pics of how I trimmed and bent the inboard end of the flaps to fit.

Electric flap conversion
Since the mechanism for this is in the fuselage I put this below in the Fuselage section.

Fuel tank vents
There are two different fuel tank vent systems depicted in the current RV-3B plans. First, drawing 12 of the new RV-3B wing plans calls out a system where the lines come into the side of the fuselage from each wing tank, go forward to the firewall, turn toward the center and go into a "t" where they meet. Then the single output of the "t" loops up toward the top of the firewall and back down to exit the floor just aft of the firewall in the center. An extension is shown once the single line penetrates the floor with a 90° elbow at the end thereby facing the relative wind. In the fuselage plans drawing 37 a different scenario is depicted where the lines also penetrate the side of the fuselage, but then go up from there forming the requisite loop just forward of the F-303 spar bulkhead and straight down to penetrate the floor. The depiction is from the front and so doesn't show where the penetration is located fore/aft. It does depict an extension from the floor penetration so it kind of looks like the penetration is forward where the aluminum fairing is thickest — at the rear it tapers down to nothing. I spoke with Van's about the vent system and we both agreed that a single vent for both tanks is a BAD idea... a potential single point of failure should the vent become damaged or clogged. It's also inconsistent with every other RV model. I therefore installed dual vents and have the loop attached to the forward side of the F-303 bulkhead so as to protect the vent line. The vents exit through the floor just forward of the the wing spar bulkhead. The aluminum fairings on the bottom of the fuselage have flattened out at that location as they come aft. As usual pics would help explan and I'll post some here as soon as I do final assembly.

Pitot tube
I know the standard RV bent aluminum pitot tube works just fine, but it just doesn't look very aviation-like to me so I opted for the pitot tube and mount from Evan Johnson. Further info here.

Wing lights
I opted to install Duckworks landing lights in both my wings. Yes, they make a model to fit the RV-3 which has a different wing profile for the lense. Being familiar with how much better HID lights are than halogens I also opted their HID kits. I aim both lights for good coverage in the taxi attitude. That gives you good lighting while taxiing and also in the flare while landing. It does not provide coverage when on approach, but then that's what I use runway lights for. One bad thing about the HIDs is that you can't set up an wig-wag circuit on them due to their start up time. I hope to find a workaround some day because I really believe in the safety benefit of wig-wags.

Tank leak
With my Airworthiness Certificate in hand I fueled the plane while carefully calibratinh my EFIS fuel gauge tables (the AF3500 has two fuel quantity tables, one for flight attitude and one for ground attitude, very handy feature!). The next day there were blue stains under my right wing. Great. The good news is that the leak is at the inboard end which means I could get in through the inspection cover to reseal it from the inside. I would much rather remove the wing than attempt to take the tank off the wing. It would undoubtedly require repainting the wing which I don't want to do. Once I had the wing off and the inspection cover off I found the leak very quickly, it was in the joint between the back baffle and the inboard rib. I Prosealed over the top of the joint and put everything back together... no leaks!

Further wing construction notes from RV-3B builder Dan Benua who built his own wings (non-QB):
Dwg 9 - Flaps. The flap plan needs clarification regarding the placement of the inboard rib FL-303.  The drawing shows the web of this rib intersecting the flap spar FL-302 at about 48" from the outboard end of the flap.  This is coincident with the inboard edge of the wing skins, but more than 1.5" out from the side of the fuselage. The consequence is that flap control linkage connects to the Wd-306 weldment well outboard of the fuselage side requiring a large hole in the F-325 bottom skin for the linkage. Randy solved this problem by adding a large fairing to cover the required hole.  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!)

Also on Dwg 9, the W-319 flap brace is shown 48" long.  The supplied material in the kit is 46.75" long.  This is OK, but the plans should be corrected.

Drawing 9 shows the Wd-306 weldment with a linkage attach bolt perpendicular to the web.  In the supplied part, the linkage attach bolt is parallel to the spar.  This is shown correctly on Dwg 30.

Fuel tank attach to spar and W-324 L.E. joint strip.  There is confusion caused by inconsistent specification of the spacing of the AN-509-8R8 tank attach screws.  Regarding the spacing of the screws along the rear edge of the tank, the following options are provided:
Dwg 12, Top View: 1.5" spacing,
Dwg 12, Section C-C': 1.25" spacing
Dwg 9, Wing Skin Plan View: 1.75" spacing
SK-34, Tank Hole Pattern: 2.5" typical spacing

Regarding the screw spacing along the W-324 joint strip we get the following options:
Dwg 12, Section A-A': 2" spacing
Dwg 9, Wing Skin Plan View: 2" spacing
SK-34, Tank Hole Pattern: 2.5" spacing

I drilled my tank for the 2.5" spacing before realizing that I had so many other options!  I expect there isn't a significant structural difference, but I'm be unhappy if the tank skin edge doesn't lay down flat because my screw spacing is too large.

One more issue is the joint between the W-303 inboard bottom skin and the W-304 outboard bttom skin.  This lap joint is shown on SK-36 and Dwg 9 with 5/8 spacing between rivets.   In current kits the outboad wing skin is supplied  long enough to create a double row of rivets at this intersection.  This allows the station 61.5 wing rib bottom flange to be fluted on 1.25" spacing just like the other wing ribs.  I chose a zig-zag pattern for the rivets on this joint with alternate rivets penetrating the rib flange.

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Notes from fuselage construction...

Firewall weldment edge distance
The standard firewall weldments have steel "ears" that are not welded together. As you can see from the picture they way they line up causes a problem with maintaining edge distance. Tom Green at Van's advised to curve the longeron in a bit to get edge distance. Preloading components is normally a no-no, but he says it will work out in this situation.

Firewall weldment gussets
Both the RV-4 and RV-8 have gussets extending from the lower firewall weldment up onto the vertical angle in the vertical plane, and at the top weldments in the horizontal plane, whereas the RV-3 does not — I remembered this having built an RV-8. Turns out you can use the RV-8 gussets, p/n F-855PP-R and F-855PP-L, which fit with only a very minor modification. This mod is not approved by Van's, and you always need to be careful when you shift load from one place to another, but this made sense to me. The parts are about $2.50 each from Van's.

Smooth fuselage skins
To avoid having to cut-off and remake the aft fuselage bulkhead flanges as many -3 builders have done, and as is described in the manual and plans, pay extra attention to the height of the bulkheads when jigged. Sight down the edges, or us a long straightedge, to make sure they line up. Adjust by either shortening the bulkhead or tipping it forward or back slightly. This works because there is no prepunching in the skins, this would never work with one of the newer kits. Then the standard flanges will then work with minor bending or shimming. Same goes for the upper bulkheads when mounting turtledeck skin once the fuse is out of the jig. I ended up needing some minor shims on the bottom skin/bulkhead joints, but did the turtledeck with no shims at all, just leaned the bulkheads for/aft a small bit for a good fit. One trick most builders already know is once you have things riveted, go back with a backrivet set in your rivet gun and lightly hit the rivets from the inside out to eliminate the depressions that inevitably get formed during riveting. Then the outside can be dressed with a flush set if there are any high spots. Using this technique I'm pleased with the way my fuselage came out, both top and bottom.

Front/rear spar distance
Reports from several builders indicate that the distance from the front to rear spars on the QB wings can vary a bit. Therefore builders would be well advised to wait until they've received their QB wings to get the actual distance from the front to rear spars so that distance can be used in locking in the carrythroughs in the fuselage (bulkheads F-303 and F-305). The plans specify 24 15/16", my wings both had 24 13/16", I'm glad I waited so I could get it exactly right. If you are building your wings yourself it won't matter because you'll have built the wings before you do the fuselage and will have them there to measure, just be sure you measure the wings and build the fuselage to that dimension.

F-325 bottom skin
As supplied the F-325 bottom skin is barely long enough. Make sure you don't trim it any lengthwise before fitting it. Even then it will provide proper overlap on the bottom (top as jigged) but be slightly short as it wraps around to the lower fuselage stringers.

Longeron rivets
The plans on both the RV-3 and RV-4s call for 1/8" AN426 flush rivets at 2.0" spacing along the main upper longeron (bottom as it sits in the jig). All later RV models were changed to 3/32" rivets on 1.0" spacing. Since all the later model RVs use this spec it is obviously adequately strong. Changing to the smaller rivets and tighter spacing makes for a much nicer looking joint with less scalloping.

Seat step, stick mixer cover
The plans call for two rectangular pieces of .025" aluminum reinforced with .025" angle to cover the boxes created by the seat area ribs adjacent to the stick mixer box. This is the area where the pilot is supposed to step when getting into the plane. This method leaves the very large stick mixer box open, and leaves the edges of the seat pan and several ribs exposed... just not a very tidy way to finish things off. I therefore fabricated a two-piece cover that serves thesame function as the seat step called for in the plans, but covers the entire area better and improves strength by tying everything together. It is mounted with #8 screws and removes easily. Note fron the pic that I have also installed a crotch belt anchor. This pic shows it before I changed it to two pieces which I found was necessary for getting it in and out once the throttle quadrant and right side console were in place.

F-321 ribs
The F-321 firewall brace ribs did not fit as supplied. I have spoken with at least two other RV-3B builders who report the same issue... the angles don't line up. In place of the supplied part I fabricated my own using some .032" sheet with .063" angle riveted to the top and bottom as flanges.

F-305 gussets
The RV-3 is the only RV model that does not have gussets that triangulate the seatback bulkhead with the main longerons and thereby providing support to the seatback as it presses back against the bulkhead. I checked the plans for both the RV-4 and RV-8 and found that the gusset parts from either should work with just a small bit of modification. In my case, since I opted to build the steel rollover bar, I designed an F-305 support gusset into the mount, see details on the rollover bar.

Rollover bar
RV-3s built with the slider canopy have some built in rollover protection that comes from the windscreen bow, but -3s with the tipover canopy have none unless the builder specifically builds one. The plans have a design for an aluminum box that fits at the forward end of the turtledeck behind the pilot's head, then the manual has a drawing of an alternative structure made from 4130 steel tubing. The aluminum structure was attractive to me because it looked easier to build, but when I saw one in person I just didn't like the aesthetics. Therefore a call was made to my builder buddy Randy Griffin who came to the rescue by welding me the structure you see pictured. We used the manual drawing as a starting point and then did a bit of customizing including the smaller diameter crossbar and also incorporating a rib for the F-305 seatback bulkhead. Interestingly, the RV-3 is the only RV that does not have some sort of rib here to support the seatback as it rests on the F-305 bulkhead. I had the rollover bar powdercoated satin (60% gloss) black and think it looks great. It should visually almost disappear once the plane is done and should prove handy for moving the plane around. If you go this route be careful with the dimensions, especially the height, or your canopy frame will not clear it as it tips over. The 17.25" height spec in the manual looks to be right on.

Full swivel tailwheel conversion
The RV-3 kit comes with the old style partially swiveling tailwheel. All RV kits shipped since 1997 use the newer breakaway type full-swivel assembly. This makes hangar maneuvering much easier and prevents damage to the rudder bottom and other parts from over-rotating the tailwheel by unkowlegable folks trying to move your plane around. With the non-breakaway tailwheel you therefore need to pick up the tail of the airplane to maneuver the plane in tight spaces.
Retrofitting the full-swivel variety to the RV-3 is not as simple as just bolting up the new style assembly. The RV-3 tailwheel spring is .75" diameter at the fuselage weldment and tapers down to nearly .5" at the aft end where it makes the ~80° bend. The newer spring bars are larger diameter, especially at the aft end. Therefore using the old spring bar by simply cutting off the bend at the aft end is not that simple because the diameter of the bar is too small for the new tailwheel assembly. This can be made to work by having a bushing machined to allow use of the smaller bar end. This way the lighter original spring bar is used yet you still get the functionality of the newer tailwheel. Unfortunately full swivel tailwheel assembly itself is slightly heavier, but I think the additional functionality is a worthwhile tradeoff. The picture shows the stock spring bar with the aft end cut off and the new full-swivel assembly mounted. Not visible is the machined bushing that goes inside to allow it to fit the smaller spring bar.
NOTE: as of 2007 I understand Van's is now supplying a standard RV tailwheel spring, tailwheel assembly, and the fuselage weldment to fit them.

F-302B part error
The instrument panel mounts to the F-303 bulkhead via a u-shaped piece of aluminum called a F-302B. Be advised the parts supplied are the WRONG DIMENSION, they are too wide by about .5". This will put your panel .5" aft which in turn effects the canopy frame, forward cowl skin, etc. Carefully studying the plans, and putting the canopy frame in place, reveal the problem. Turns out you can use a piece of the F-303G which has the correct 1 1/16" width which yields correct distance from panel to seatback bulkhead as called out in plans.

Removable instrument panel
Knowing that panel updates are always a possibility down the road, I've created a subpanel/panel that allows the panel itself to be removed and even replaced without messing with the way the forward cowl skin and canopy fit. Pictures and details are on the Panel page.

Cockpit side consoles
Cockpit resource management and the art of cockpit design — one of the fun parts of building your own airplane. See the Cockpit page for my thoughts and solutions in this area.

Electric flaps
Van's only offers the RV-3B with manual flaps activated by a "Johnson bar" located on the left side of the cockpit. This creates a problem if you want to install a throttle quadrant in a traditional location on the left cockpit wall because the flap handle hits the quadrant unless you mount the quadrant so high that it then becomes ergonomically awkward. Shortening the flap handle is not a good idea, builders who have done that report that the air load at 100 mph is considerable. I therefore pursued an electric flap solution so as to eliminate the flap handle. Being familiar with the RV-8 motorized flap mechanism I thought that the motorized "linear actuator" could be mounted just behind the seatback and connected directly to the flap arm. The electric actuator assembly Van's sells is the same for the RV-6/7/8/9, can be purchased for $280, and has been made by two different suppliers over the years.
I cut the flap handle off flush with the crossbar and had a little u-bracket (which can be obtained from Van's if you ask nicely) welded on the left flap arm near the aft end to accept the end of the actuator. As you can see in the pic I used a spare inboard aileron bracket to attach the top of the actuator to the seatback bulkhead. The standard actuator has 5" of travel which is too much for this application so the actuator needs to be modified. In my case I needed 2.6" of travel. Van's current supplier, Usher, was not interested in making a custom version for me however I found Motion Systems quite flexible and their web site allows you to custom configure an actuator for your application. DO NOT MENTION WORD "AIRPLANE" if you speak with them!
With the shorter travel of course the flaps deploy and stow more quickly, in my case it now takes 3 seconds to fully deploy or stow the flaps... nice! In all this conversion has worked out very well. If you're building an RV-3 I recommend you consider this mod. Quite a few builders have asked me what model I ordered, here are the particulars: model 85615 2.60" stroke, 15:1 reduction, 7400 rpm motor, support bushing, cover tube w/seal, rod end TM-4, type C gearbox housing, 1/4" dia 90 std.

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Notes on Finish Kit items...

Cowl
The RV-3 now comes with the modern style honeycomb-reinforced epoxy cowl, the same material as the rest of the current RV family. This cowl is both lighter and stronger than the older style polyester resin cowls and is less prone to warping over time. If you opt to install anything other than a carbureted O-320 you may need to understand a bit more about the RV-3 cowl, as I found out the hard way, so here is some background information you should be familiar with.

LEFT: O-320 intake scoop, RIGHT: O-360 scoop. Note that O-360 scoop is wider, one inch lower, and the intake is several inches more forward.
Intake tunnel, should line up perfectly with FAB.
The classic lines of the RV "cheek cowl", looks good even unpainted!

The RV-3 cowl is the same as the RV-4 cowl, it's made in the same mold, just layed up a few inches shorter. When it is layed up they also shorten the honeycomb reinforcement pieces by 3". I suspect the difference between RV-3 and RV-4 finished cowls is a bit greater than that, more like 6", but have yet to take an exact comparison measurement. On Van's order form the RV-3 is only available with a cowl for a carbureted O-320 configuration. This is designed to work with their FAB-320 filtered airbox and I'm sure it fits well. However even though I am installing the approved O-320 I opted for Bendix style (Silver Hawk) fuel injection. The Silver Hawk servo body is 7/8" taller than the O-320 carburetor. I thought I had a workaround by modifying the FAB-320, but in the end it still wouldn't fit. After exploring all options with Van's, in order to get the clearance I needed for my servo and a FAB, we concluded the only way to get things to fit is to order a new lower cowl with an O-360 intake scoop. Whereas an O-320 carburetor and an O-360 carburetor are different heights and have a different inlet pattern, fuel injection servos are the same in every respect for the 320 versus 360. An RV-4 cowl can be ordered for either an O-320 or O-360 configuration, the only difference is that the intake scoop on the 360 version is larger to accommodate the taller carburetor or fuel injection, and also the wider FAB. Therefore I had to order a new lower cowl specially made for my installation. You could call it an RV-3 lower cowl with an O-360 intake scoop, or you can call it an RV-4 O-360 lower cowl with the honeycomb shortened 3", same difference either way. Of course I discovered all of this AFTER my cowl was already fully fitted, both top and bottom. So, in the final analysis, if you're installing either an O-360 (not approved by Van's) or a Bendix style (not sure about Airflow Performance) fuel injection system then you need a special lower cowl with an 360 intake scoop and a FAB-360 to use with it. Details on the FAB can be found on the Firewall forward page.

Cowl fasteners
To fasten the cowl I will use Skybolt Clok® 4002 series fasteners (Camlock knock offs but improved) around the perimeter of the firewall instead of the plans specified hinge, then the standard hinge on the horizontal upper/lower cowl seam. I used this system on my RV-8 and it worked great. I've also recommended it to many others who have used it and all are pleased with the results. The Skybolt range of products can be a bit daunting at first so here are the parts used in my installation for anyone interested: SK40S5-2S studs, SK-OS grommets, and SK245-4 floating receptacles. More info and their catalog can be obtained at www.skybolt.com.
When installing camlocks around the firewall you simply fabricate a strip of .063" aluminum, curve it to match the firewall, and rivet it around the perimeter of the firewall with the same rivets that attach the firewall flange and the forward fuselage skins. You'll need to countersink the rivet holes to accept the dimples in the firewall. This strip goes inside the firewall flange. I used 4 camlocks on the each side of the lower cowl and 13 across the top cowl for a total of 17 fasteners. Skybolt recommend 3-4" spacing and most of mine are right in that range.

Oil door
Fiberglass oil doors have a tendency to bulge when in flight from the pressure inside the cowl. To eliminate this problem I laminated a layer of carbon fiber cloth followed by a layer of regular e-glass on the inside of my oil door to stiffen it up. It's amazing how much stiffness that single layer of carbon fiber adds! Alternatively, I could have riveted on two pieces of .025" x 5/8" aluminum angle that is fluted to form fit the curve of the door. I recommend you use one of these techniques to provide some extra stiffness, the majority of builders who don't report bulging, and this applies to almost any model RV.

Cowl cheek extensions
The RV-3 uses aluminum cowl cheek extensions to bring the shape of the cowl cheeks back onto the fuselage. Turns out these parts are very difficult to position and drill correctly. I went through three sets in an attempt to get them right, and have some extra holes in my fuselage to prove it. I never could get them to fit to my satisfaction so I abandoned the aluminum and made some out of fiberglass. I took one of the metal cheek extensions, flush riveted it to two pieces of 1/8" angle and used that as a crude female mold. I first laid up a two-layer piece with 9 oz. cloth and wondered if I should use a three-layer for extra rigidity because although the two-layer piece formed into place nicely it flexed a bit.So I laid up a three layer piece next. I found the two-layer part to me much easier to form into position and still adequately strong so that's what I'm going with. One could build even better parts by forming a shape with foam and glassing over it, but that's just more work than I want to incur. Using the above method the parts turned out pretty good, fit much better than aluminum, yet look like aluminum because of the way they were molded. To complete the installation I riveted them to the fuselage using ProSeal just for some extra security and so there won't be any paint cracking along the edges. I'm very pleased now with the results and wish I had gone this way from the beginning!

Canopy
RV-3s are built with one of two types of canopies, the tipover (like the RV-4), and the slider (like the RV-8). The kit comes only with the frame for the tipover type, but plans are provided for the slider frame if the builder chooses to build his own. I'm going with the tipover type for three reasons. One, I think it is better looking. To me the slider just doesn't look right on such a short plane whereas the tipover makes the lines of the plane appear sleeker and more graceful. Second, the tipover is a fair amount easier to build. And third, when formation flying, there is no substitute for the unrestricted visibility afforded by the full bubble canopy. When formation flying in my RV-8 the roll bar and fairing didn't pose too much of a problem when flying wing, but when you move to the slot position it was in the way big time. Yes, tipovers can get hot on the ground in the sun which is why I will make sure to put a taxi position for the latch to keep it open a bit while taxiing. Cutting and fitting the plexi was straightforward and seemed quite a bit easier than the RV-8 just due to its small size.

The ill-fitting attempt at aluminum

LEFT: posterboard & packing tape form is inspected by Van himself. RIGHT: immediately after the layups.

LEFT: the skirt after removal. RIGHT: after initial trimming, fits perfectly!

Just after painting the completed skirt

Canopy skirt
The canopy skirt, as on most RV designs, was a bit more challenging than the canopy itself. Van's provides aluminum side pieces that extend from the instrument panel back around to the center of the back. There was no way these were going to fit as supplied so I opted to cut these panels even with the seatback bulkhead creating a seam that lines up with the fuselage side skin as I have seen some RV-4 builders do. Rather than make the front edge fairing out of fiberglass I wanted it made out of aluminum so that the entire skirt was aluminum and can be de-riveted should I ever need to replace the canopy. All of these aluminum pieces are required to be formed into compound curves, something requiring advanced metalworking skills and tools that are beyond me. I therefore solicited the help of some local sheetmetal experts for a go at it. They fabricated the front fairing strip and the two aft pieces but they still didn't fit right. I therefore gave up on metal and fabricated a one piece skirt out of fiberglass. The toughest part was figuring out what to use as a "form" to lay the glass up on. After considering lots of options I ended up using posterboard cut into pieces and then slit in various pieces to allow it to form. This was secured with lots of little strips of packing tape to initially lock in the shape, then larger pieces to smooth it out and provide the surface to layup on. For those interested, I used 3 layers of 8.92 oz. e-glass and West Systems epoxy. Of course finishing fiberglass is LOTS of work... seemingly endless sanding and filling.
In the end I think it was worth it, the finished part fits like a glove and looks good too. Due to the form fit shape it should be effective at keeping the drafts out and look good while doing it.

Canopy skirt edge seal
The fiberglass canopy skirt fits perfectly on the fuselage both fore and aft, there are essentially no gaps that require any sort of seal. The skirt will abrade the paint however just from contacting it. I discovered a very effective solution for this... adhesive backed felt. Go to any fabric store and ask for it. For about $1.29 a sheet you will find 8.5"x11" sheets of adhesive backed felt in a variety of colors. Cut it into 1/2" strips with your ruler and put it on the very edge of the skirt. You'll find that once it is cut into strips it bends and conforms nicely. I've used this technique on both my RV-8 and RV-3 canopy skirts with great results.

Canopy latch
Van's plans call for the latch to work by moving it forward to unlatch and move back to latch. This seems very counterintuitive to me. Several RV-4 builders have reversed the operation and I did also. I have also opted to use rod end bearings to attach the rods to the lever rather than simply slitting and flattening the tube... much more elegant. Finally, rather than route the rods through the bows if you fabricate a bracket and locate them inboard you then have room for two latch holes, one for closed and one for taxi position to let in air on hot days. There will be microswitch in the forward bottom hole that will enable a "canopy open" alarm should I forget to latch it.

Canopy support strut
The RV-3 manual instructs tipover canopy builders to use a simple piece of cord to limit the canopy in the open position. While certainly simple, the problem with this method is that if a gust of wind or prop blast comes along the canopy will slam closed, probably damaging it. I scratched my head for months trying to think of a solution that would provide the stop when open, secure the canopy in the open position, yet be simple and light. I looked at two basic methods: articulating hinges, and gas struts. Due to some curves and the resulting geometry I just couldn't get a hinge system to work. Struts are used on all the RV tip-up models and are a good solution especially if you can get the geometry to provide some force holding it closed, then go over center and push it open while providing a stop at the extent of its travel. After much more brainstorming over several months I came up with the solution pictured. The strut was sourced from www.mcmaster.com (p/n 4138 T581, 20.12" extended length, 8.27" stroke, 15 lb force) and was around $19, and I made the brackets myself. It works great!

Brake lines etc.
Instead of using the solid aluminum 1/4" (AN4) tubing specified I used flexible Teflon/ss lines and fittings. I was concerned that the solid tubing could fail some day with repeated flexing, especially when removing/replacing the caliper for brake maintenance. If you go this route I recommend you go with the smaller AN3 size hose and fittings which is smaller, more flexible, and still has plenty of capacity for the brakes. The hose and fittings were from XRP but the same parts can be obtained from Aeroquip, Earl's, or most other hose manufacturers. I also used individual brake reservoirs instead of the single reservoir with guaranteed-to-leak plastic low pressure line Van's provides. The reservoirs are part number A-600 from ACS.

Empennage fairing
Van's fiberglass parts,especially in the early days, were notorious for not fitting. Check out the initial fit of my empennage fairing (upper left pic). Hmm, that's not going to work very well. After a bit of headscratching I decided to build the empennage fairing from scratch. I cut the supplied fairing up and use the pieces to form a surface to layup on, used some clay to form fillets at the leading edges, and layed up three layers. I layed it up in one piece extending all the way back under the HS and will leave it as a one piece fairing. I modified the aft end to make it removable as a one piece unit.
BTW, I've seen two other late model RV-3B projects and the emp fairing fit was exactly the same as mine. Clearly the mold needs to be corrected.

Gear leg fairings
I used the standard fiberglass gear leg fairings supplied with the finish kit. Note that these are a newer style than what was supplied with older kits. Van's now sells intersection fairings for several RV models and I found that the U-719R&L lower intersection fairings, which are technically for the RV-7, fit fairly well. They don't have any uppers that will work however so I had to make mine from scratch.That's probably just as well since you really need a custom fit in this area.
I mounted my gear leg fairings without the standard hose clamp retention method. Rather my fairings are located by the upper and lower intersection fairings. The lower intersection cuff has a screw that goes all the way through the leg fairing thereby preventing it from sliding up and down. Then the upper cuff will have some UHMW tape inside to allow for some up/down movement as the gear legs flex. Everything was aligned using the standard method specified in the manual.

Gear leg stiffeners
The plans provide for optional wood gear leg stiffeners. I preferred not to add the weight or complexity and did not install them initially. From checking with lots of builders with rod-legged RV models it seems that if you balance the wheel pants fore/aft and manage tire pressures that gear leg shimmy can be avoided. BTW, you balance the wheelpants by using lead shot in epoxy in the nose of the front half, you can find an excellent "how-to" article by RV-6 builder Jeff Point here.
After flying the plane I did have shimmy initially but kept reducing tire pressure and found that at 22 psi and below the shimmy went away, well mostly. I'll air up to 24 psi, then let it leak down to maybe 18-20 before filling back up. I'd bet that different tires have different shimmy characteristics too depending on weight, sidewall thickness, rubber compound, and hysteris properties. More on that on the Maintenance page.

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