Hi Guys,
It's really great to see this thread. I just finished assembling a Blue/Yellow XL, but I haven't flown it yet. It's got a new BME 50 with a J&A muffler, and the new Zinger 22x8 prop. A 2700mah Nimh 5-cell pack powers all Hitec servos. A Hitec 5945 on the rudder 180in/oz @ 6v, two 5925's on the elevators, 605BB's on the ailerons, standard servos on the throttle and smoke valve. The rudder, elev and ail servos are connected with buffered/amplified extensions and y-harnesses. I debated and vacillated between the ZDZ 40 and the BME 50. So far in my short ground tests the BME 50 started easily. The carburetor manifold was about 5/8" long which meant the carb would have to poke out, but I cut a new manifold from 1/4" plywood and got the carb to clear the inside of the cowl by 1/8". I hope it does not detune the engine but I don't think so, I got 7060rpm on that prop, and the engine is brand spanking new. It's very light, without the muffler or spark plug it weighed 3lbs 1oz. I gave the ignition a 5 cell 1650mah Nimh from RadicalRC.com. I hate the way I had to cut so much of the cowling away at the bottom so that the J&A muffler's exhaust stacks would clear, but hey, it got that much lighter. I basically have a channel 3" wide from the front to the back along the bottom. With the front cowl holes open it ought to run cool even on the longest hovers.
Ben, I too did not like the way the elevator servos were supposed to be mounted so I made a hole opposite the right side's hole which is high I believe. I filled in the other two holes on the left side with balsa. I did have to shim the rear of each servo 1/8" but I have 1/16" clearance between the servos now. No big deal there. I know the geometry of the two linkages would never be the same without that mod.
I put a Perry Micro-oscillating pump on the engine mount, and it does pump the smoke fluid but I don't know how well the smoke system will work. I'm going to try lamp oil since I have it, and the citronella smell will at least chase mosquitos away in the torque roll. A servo-operated pinch valve with needle adjustment allows me to turn the juice on and off and adjust it. A 14oz Dubro fuel tank is matched by a 14oz smoke tank, both sit nicely on the floor just ahead of the spar tube.
Ben thanks for all the pics of your XL, I will get a few pics of my plane and post them as well. One thing I did was connect my elevator servos into separate receiver channels and then mix Ailvators so that the elevator servos have aileron action also. This is real nice since I don't need an adjustable y-harness, and I can set the endpoint and centering of each servo separately. I am using this feature on a Pizzaz and it really gives a lot of aileron authority in a hover and torque roll. It really helps in the wind to keep the airplane rolling in a torque roll, and just a little right aileron lets it hang straight all day. So I set it up in the Diablotin XL as well. There is a preset mixer available in the Futaba 9C but I didn't use it because it stays on all the time, and in a snap or tumble maneuver the elevator authority is reduced with Ailvator turned on. So I used three programmable mixers. The first mixer just slaves Aux1 (ch7) to Elev and it stays on all the time, no switch. The second mixer slaves Elev (left side) to the left aileron (ch1). The third mixer slaves Aux1(ch7) to Flap (ch6). Both of these mixers are on the same switch. I will let you all know how the test flights go and how it flys. I don't have an all-up weight, I only have a 5lb scale. I imagine it is not the 12lbs advertised, probably 14 lbs. With 26lbs of thrust this will be the highest power/weight ratio of any airplane I have owned in the 22 years I've been building model airplanes. I'm very excited about it because I thoroughly enjoyed flying a 1/4 scale Sig Cap w/YS120 at 11lbs so this will be a real hoot even at 14lbs. The cubic wing loading for this model is about 5.78, which is down around where the Magic 3D flies. They say a good 3D machine is around 7 to 7.5 cubic wing loading, at less than six this should be a blast. I can't wait to fly using the cheap juice too. This is too good to be true. -Tom