Giles VI 2010
Wingspan 65 in. Wing Area
680 sq.in. Weight 45-47 oz. Stab Area 170
sq.in. Avg. Chord 10.4 in. Aspect Ratio
6.2 Tail Volume .47
The high aspect ratio wing carries
weight better and handles the wind better. The long wing slows
down less in maneuvers. The narrow tips hardly notice
gusts. An LA 46 or similar power engine is highly recommended
with an 11-12 in. prop.
The deluxe kit includes all the wood and
foam parts, laser cut if needed, hardware, landing gear, SLC
covering, silkspan, and control hardware(not including parts for
the moveable rudder.)
The TrueBeam(tm) hollow wing is
self-jigging. The control sufaces are also foam core, with a
balsa outline. The fuselage has a foam core from the spar back
with a laminated balsa/ply/hardwood front end.
More than you ever wanted to know..........
A few seasons of experimenting and I found that I really didnít need to change much. The current plane(Iím up to the 6th version and about the 10th wing) still uses the NACA 0018. The quarter chord is swept forward a few percent, the leading edge just doesnít sweep back very much. The wing is hollowed and used the True Beam(tm) design. The I-beam spar caps are captured in foam. The web of the beam slides in to glue to the spar caps. I switched to a foam rear spar to reduce building time and weight and money.
I finally gave up on the bladder tank. When I got the bladder filled properly it worked extremely well. Problem was I couldnít fill it right more than 2 tries out of 3. Not real nifty for contest work. Both a Sullivan SS-6 tank and a GRW hopper tank work fine. Properly set up, a Sullivan tank runs out every last drop of fuel. A little heavier, but easier to fill. Contest performance has been quite good. Iíve been able to post middle of the pack flights in the low 500ís which is better than my lack of practice should produce. The plane definitely has the potential to score well. The large fuselage and the horizontal strip color scheme, along with the angular fuselage and fin really make the flats in the sharp maneuvers stand out.
The biggest change has been the addition of a Rabe rudder. It really does a number on taming down adverse yaw in sharp outside corners. I made the rudder about 4.5 in. high by 1.2 wide, just a trim tab at the lower edge of the rudder. Du Bro ball links and a couple of short horns hook it up very easily. The neutral is set about 1/8 in. right. The rudder moves about left to zero offset and 5/8 in.right, from full up to full down. Someone that knows what they are doing could probably trim it finer than I, but it made such a big, positive difference I havenít touched it again.
After much experimenting an LA 46 is probably the best engine for this plane. The LA 40 will work, but it requires 25% nitro to get the horsepower. The 11/4 range props work well. Current favorite is the Master Airscrew 10/5 3 blade depitched it to adjust the level flight speed as needed. With the motor running the stock muffler, this combo is starting to take on a lot of piped engine characteristics. The smaller diameter 3 blade prop still pulls well, but it doesnít seem to pick up as many revs doing maneuvers in the wind. The 11/4 was a good all-around prop.
Current venturi is .277 id, using an OS
valve assembly. This is a bit smaller than the generally favored ST
nva in a .280 venturi. Venturi size is one of the things that tames
the 4-2 break. Sizing it down will reduce the power pick up, as it
reduces the power peak a bit. The LA's work pretty well with a
prop/venturi that runs a fast four stroke at around 10,200rpm on the
ground but with a venturi small enough to limit the peak rpm to no more
than 11,500 rpm.
Weight is a critical
issue. 45-47 oz. is about the max for a nice, contest-worthy ship. Iíve
built three to this weight with an LA 40 or 46, stock muffler, and
light weight wheels. Weíve experimented with three tail
variations. Firstly, building the stab up out of quarter inch strip
stock and the elevators out of 3/16 in. saves a significant amount of
weight, all far behind the CG. The all wood empennage weighs about 68
gr. The built up version about 45. Well worth the effort. You can
even build up the fin/rudder and save another 15-20 grams. I have
been amazed how strong these flimsy-looking things are when covered
with SLC covering and painted. Larger stabs are fun too. #2 was 27
in. span, a total of 140 sq. in. for the stab/elevator. It was
noticeably more stable than the stock tail, mostly because the larger
stab would tolerate the CG further back. The CG always seems to end
up too far back! Then I tried one with a 170 sq.in. tail- 7.5 in.
rooth chord, 4.5 in. tip chord, 27 in. span. The elevator was still
2.5 in.wide to keep the control forces from getting too large. The
bigger stab is even more tolerant of CG. I went from a chip muffler
to the stock muffler with the same control movement. It really made
no difference in turn performance, although the extra nose weight did
make the ship steadier.
Iíve been doing a fair amount of crash testing. Sure takes itís toll on the purdy paint jobs. Nuff said that the Giles can really take it. The last one I put straight in from about 60 deg. and it only suffered a few cracks in the fuse and a slightly loosened right wing. The biggest problem with severe crashes is that they can soften up the nose leading to vibration and fuel foaming/fuel feed problems. If you do crash yours and have this problem, the only solution is to build a new fuselage. With a little careful hacking the wings can be stripped off and the stab and fin removed to reuse on a new fuselage. The current version of the kit includes ply nose stiffeners to prevent the problem for at least one crash.
The latest covering interation is pretty simple. Sand the wood down to the foam(carefully please!). Fill with lightweight filler. Sand smooth, almost to the point where the foam starts to cut. Vacuum the wing thoroughly. Iron on the SLC covering. Apply a second layer of covering- either silkspan put on with water-based varnish, or another layer of SLC. Sand the silkspan thoroughly. Seal with another thin coat of varnish and then prime. If you use SLC for the second layer, simply prime with auto primer and sand thoroughly.
More even more back story before 2004........... I loved this project, even with all the sanding. It feels great when a plane turns out almost exactly as you wanted it on nearly the first flight. The first Giles did just that. It came out about 3 oz. heavier than I wanted, 45.5 oz. But the wing was bigger, 740 sqin. so it carries it just fine. I spent quite a bit of design time balancing the fuselage length and size, the tail size and weight, and the wing position to minimize the need for balance weight. Didnít quite hit it. I had to put the muffler on the LA 40 and add another ľ oz. of nose weight. That is probably where most of the unexpected weight came from.
2002 Plane Specs: Span 60 in. Wing Area 735 sq.in. Tail area 124 sq.in. tail moment 24 in. wing chord 12.25 Kt= .33 Tail Volume. Engine: LA 40 with stock muffler 10/4 Zinger prop. 10% RC fuel.
The carb is set at about ĺ throttle to keep the speed down. The tail volume is the same as the first Giles(after the tail was replaced). It uses a larger tail(124 sq. vs 105) on a shorter tail moment(24 in. vs. about 27 in.) The slightly higher aspect tail lowered the control forces a bit making control movements easier and more consistent. The control feel varies less with speed We did the first flights on slightly short lines, abou 57 feet. Took off smoothly from the grass, which still hasnít really started growing. The plane showed a very slight right roll. Inside and outside turns were pretty equal. It was also a bit twitchy, tending to overshoot in square corners. Yaw in the squares was a bit much too. After a couple flights we added ľ oz. of tip weight, and ľ oz. of nose weight. I also switched to the longer lines, about 63 feet, and put the down line in back. Now everything is close to working right. Less twitchiness, I can feel the neutral and hit solid corners with little overshoot. The tipweight stopped the slight inboard rolling tendency, and the reversal of the lines calmed the yaw in square corners quite a bit. We managed to get one flight shot with the digital camera. Digital cams are the pits for action shots arenít they. A few notes on building. This plane is finished with just two layers of OO silkspan. It was applied with MinWax Polycrylic after filling the foam with light filler. A couple of fill coats were applied and sanded down. Final finish is two light coats of Rustoleum Gloss Protective enamel spray cans with the same paint for trim.
Iíve done a lot of experimenting with finishes for this ship. Must have covered something like a dozen test panels. It seems to boil down to the fact that a decent finish weighs the same no matter how you do it. For this plane it seems to take about 7-8 ounces of finish to seal, harden, and color. The lightest finish would be simply to put several coats of varnish on the foam, after filling and sanding. Then apply the SLC covering and put on the final colors. It seems that no matter what, the heat from applying the SLC covering raises the texture of the foam. The only way I can see to get a really smooth finish would be to fill and sand over the covering. Two layers of OO silkspan worked fine. Silkspan is still pretty delicate. I got more hangar rash after it was painted than with any other plane Iíve built. It does add about 4-5 ounces of weight but the final finish is pretty presentable. Nice bright colors, fairly smooth and glossy, and durable, as long as I donít bang into things. Not nearly a 20 pointer, but Iím sure I can get another 5 points or so easier flying than sanding!!!! You may wonder where the tank is. I use a Yellowjacket(tm) bladder. It's light and reliable. The bladder is in the right wing with the access hole going through the fuselage and it comes out in the left wing. This arrangement keeps the right wing clear for easy cleaning. I have pretty good luck with the bladder. Properly filled it runs at a constant speed throughout the flight. The plumbing to get the fuel to the motor is in the fuselage. �