RCP Mig29 V4 NAMCV2 Build log - Part 2

Hi everyone -

Managed to squeeze in a little more time in the NAMC workshop (Canadian Division... :) ) today.  I put the Velcro down in the electronics bay, put the bulkhead and nose former in the fuselage and then did a considerable amount of sanding and shaping on the trailing edge of the wing, the back plate and elevons and the rudders and vertical stabs.  The sanding took about an hour and 15 minutes, so after that I thought it better just to leave the nose forming and shaping til tomorrow when I have the energy.  I find that nose forming is a bit of a fussy job, so I want to be fully committed before doing it so that my plane doesn't end up looking like Jimmy Durante... :)

In the next two pictures I wanted to show the comparison of before and after sanding of the tail plate.  It does round off some of the sharp corners and scale angles of the Mig elevons, but at 20 ft in the air I'm not too worried about it.  What I am pleased with is the reduction in drag that it gives me... :)

One thing I did note today when I was sanding the elevons was that there was a bit of flex in the small area between the main elevon surface and the "nozzle", so I put down a small piece of drywall tape and some Foam Tac and coupled with the drywall tape on the opposite side that acts as a hinge , it is now nice and strong.

Then after the glue dried, I put my clear duct tape on the bevelled part of the elevon hinge to give me the extra strength and durability that I like to have in my elevons.  I discussed that in more detail in this blog article http://migsrus.blogspot.ca/2014/08/reinforcing-foam-tacdrywall-tape-elevon.html

I know I have rambled on about the virtues of symmetrical leading and trailing edges and paying attention to detail in doing a good job of sanding in previous articles and when I was still active on the RC Powers forum, but wanted to revisit it again today.  Now I certainly was not the first one to do this, folks were shaping and sanding their foamy park jets long before I showed up, but as my building skills improved coupled with some great feedback from Stephan, I have taken my finishing skills to the next level of attention to detail and it is paying off considerably.  Even on the first plane that I really modified, the FRC Su35 MK2, I was still going with the "chiseled" leading edge on my wing and elevons.  Again, part of following the "herd" on the forums as that was what everyone was doing and was being recommended by RC Powers.  

I really don't know why it took me so long and so many planes to convince myself that aerodynamically this makes no sense.  I suppose if I was using a KF2 airfoil or had a cambered wing then maybe I might go for this shape of leading edge, but otherwise, I can't see the benefit.  Again, thanks to Stephan for helping me break out of that rut!

I did do a "half hearted" job of tapering the trailing edges on this plane, but not to the point I do now, this was a pretty sloppy job with just a few quick swipes of the sandpaper... :/

So fast forward a few planes and here is the symmetrical leading edge on the wing of my stock RCP Mig29 V4.

Also, as you can see below, I took the time to properly taper and blend the trailing edge much more on the Mig as well.

So, why all this worry and fuss about shaping and sanding leading and trailing edges and the entire plane in general?  Well, I guess it depends on how you like to fly and what you expect from your planes.  I still have probably another hour of carving, shaping and sanding to go once the plane is all together, so that is over 2 hours just sanding.  

Since buying into the tapered leading and trailing edges and truly taking the time to blend the taper by starting off with 150 grit sandpaper and then finishing with 220 grit, I have been amazed at how much slipperier my planes feel in the air.

Another bit of proof hit home the other day when I was flying the two planes show in the pictures above.  I wasn't really testing or evaluating anything, just out thrashing around having fun, but I started to notice on approach and landing, that the Mig29 V4 with the symmetrical leading and trailing edges would dead stick glide over twice as far as the Su35 with chisel edges.  Now I know I am comparing two different planes, but I had to keep power on much longer in the landing approach with the Su35 in order to maintain control whereas the Mig just kept gliding smoothly and efficiently for over twice the distance that the Su35 was capable.  

So if you fly or have to land in a really small area, this might not be something you want your plane to do, but overall I think this proves how much more efficiently the plane glides and cuts through the air when the time is taken to really shape and sand the leading and trailing edges and the entire fuselage and body.  It is almost like free speed, or free efficiency (other than a couple sheets of sand paper and a couple hours of time) without having to upgrade any equipment.

I'm finding that by taking the bulk of the foam away with the 150 grit and then gradually shaping it smooth with the 220 grit back about 3/8" from the edge, makes for a nice smooth transition rather than a rough, angular, blocky edge.  Given that most foams are not the most slippery materials with which to build an airplane, anything I can easily do to cheat the air and gain speed and efficiency is a good thing.

Maybe that is too much fuss for you and that is fine, as I have said before, do what makes you happy and build and fly how you want to, that to me is the most freeing thing about this hobby of scratch building foam park jets.  I know sanding is not one of my favorite parts of the build, but I have proven to myself it is crucial to really pushing my planes to their maximum performance.  As both Stephan and I have mentioned, don't worry about what we say or anybody else says, the moment of truth is when you are at the field flying your plane and how much fun you have.  

If however, you are looking to squeeze just that extra bit of performance from your plane, I encourage you to give some thought to really taking the time to sand and shape your plane to make it as aerodynamically sleek as possible including trying symmetrical leading and trailing edges on the wing, elevons, vertical stabilizer and rudders.  You will be amazed at how much smoother and slipperier your plane feels through the air.  I know I did the first time I tried it and I will continue to refine my sanding and shaping technique with every build.

There is a threat of rain here this weekend which will interfere with flying... :(, so I hope to keep plugging along on the build and maiden by next weekend.  

More to follow soon... :)

Cheers,

Scott