 Part Seven As promised this part will deal with the fitting of fairings etc. Fiber Glass!! Yikes!! Not really. Here you can let your creativity loose in a way. Let us start with the gear leg fairings. Read the instructions very carefully because if you do not do this properly, you will have an RV that will not fly straight. Very often you hear stories of RVs suddenly flying skew after the fairings and spats were fitted for the first time. The fact is that on a two place RV you should gain about 12mph in cruise speed with everything fitted. Also what most people do not realize it that the fairings for example is forward of the aerodynamic center of your RV, mis-alignment will have the same effect as rudder input, but in the opposite direction and generally much bigger than one would think. Then there is the issue of stiffeners. Everyone you ask has a different opinion on it. My RV mentor advised to put them on anyway while you are building and then you are 100% sure that you will not have landing gear oscillation/resonation. Simply using a round dowel and duct tape will not work.  When it comes to the strings that you have to set up, make sure that you tie them to posts or stands that will not move. The instructions also ask for all the weight to be removed from the landing gear and that the AC should be leveled. Take special care here, especially with the tail wheel RV's.  Once you are satisfied with this it is time to move on to the wheel fairings or spats. Personally I like to install them at least a ½ inch higher than what is given in the instructions. It will give you more clearance on grass and dirt strips. Once again, be very careful with your measurements when doing the alignment. Rather measure more than once before you start drilling the attach holes.  On the RV10 and RV12 I know that one has to create a “nest” from flox and resin and apply it where the brackets mate with the insides of the spats. In my opinion it is a very good idea to do it on all RV's. It just makes the assembly much more sturdy and you will not get chafing or hole enlargement if a screw is slightly loose. Then it is on to the intersection fairings. With the gear fairings aligned, be careful not to move them when you slide the intersection fairings into position. The top ones are simply a matter of aligning them and drilling the attach holes. Be careful not to drill into the spar!! I use plate nuts on the wing root fairings and rivnuts on the belly skin to fasten them. With the bottom ones you have a choice of installing them as a one piece fairings or you can bond and split them. This is really a personal choice. Should you go for the bond and spilt method, make sure you bond it properly and it might be a good idea to use a few rivets as well.  Do not forget to fit the empennage intersection fairing. A bad fitting fairing here will ruin the appearance of your RV. The part as received is usually quite uneven and as usual will need some work and trimming. Working from the front backward usually helps. I also find that that it really helps a lot to heat up the fairing slightly while it is clecoed in position and let it cool down. Areas where it does not fit well can also be manipulated by heating it up and putting pressure on it while it is cooling down. Sometimes we even use an empty bottle and roll it while it cools down.  Last but not least are all the fiberglass tip fittings that you have to tackle. The biggest being the wing tip fairings but we have not built the wings yet. Most of the smaller ones are fairly simple to fit and trim. What may be a bit of a challenge are the small tips for example on the end of the HS that you have to close up. There are various methods that will be satisfactory. My method is quite simple and easy and the result is a very smooth finish. Insert anything light like pvc, balsa, foam or similar into the open end after you have trimmed it to the correct size. Position it about one or two mm inward. In other words not flush with the trimmed ends.  Then put a piece of thick plastic (a thick plastic bag will do) on a smooth surface like glass or melamine. Mix resin and hardener and lay up two to three layers of glass on the plastic sheet. Then use the last of your resin and mix micro balloons into it. Cover the dummy end pieces with this mix. Then simply place the tips on top of the wet glass lay ups and leave to cure.  After curing you will have perfectly formed and smooth ends and you only have to trim off the excess. Next month I will discuss attaching the fairings and wings. Keep on pounding! |
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