Bob Wideman's

Genesis 33% Waco

  

  

Several in the club have asked about the progress on the Genesis 33% Waco. During yesterday’s “snow day” I had time to put the pieces together and take some photos. For size reference, the plane is sitting on an 8 foot pool table! When I got the 3W 157 engine and 32” prop I thought they looked huge. However, when installed in this airframe the engine and prop almost seem too small (look at the inside-the-cowl photo)!
 
Basically the N-struts and Cowl need to be finished, the fuselage remains to be covered, the trim colors must be applied, the Solartex covering has to be sealed with polyurethane, and the servos & electronics must be installed. The kit arrived in May of 2007, and I suppose I’ve put an average of 10 hours per week into the construction so far (probably about 400 hours total to this point). I estimate another 100 hours until the test flights. Some specific comments are provided below.
 
This is a “builder’s kit” that requires experience and patience. Don’t go for this type of kit unless you really enjoy the process of constructing airframes from ply, spruce and balsa. The supplied CD, instructions and plans are very clear in most cases. In a few instances I relied on past experience to interpret the drawings or intended outcomes. I used Gorilla glue for most aspects of the construction – this is great stuff that gives very strong joints without a lot of weight.
 
The kit arrives as a lumberyard in a big box. The laser cutting of formers and ribs was absolutely outstanding. The wings are framed-up in jigs, and they came out absolutely straight. At the time of assembly shown in the photos, wing incidences and alignment were just about perfect – all within 1/16 inch for comparisons of left & right sides. In fact, the dimensions and angles for the “N” struts on the left side are virtually identical to those on the right side.
 
The fuselage is framed up as a slab-sided rectangle of very stout laser-cut plywood, which makes it easy to build it square. Then the half-moon formers are glued on and the stringers applied to round it out. Makes a very strong and straight fuselage!
 
I had a tough time fitting the fiberglass parts (tail fairings, back and front turtle decks, wing fairings, nose ring). Lots of fitting, sanding, filling and “massaging” to get these parts to blend into the wooden framework. This was the most frustrating aspect of the construction, but in the end everything turned out smooth and seamless.
 
To add strength, the center sections of both wings were entirely covered with .75 oz fiberglass cloth. I also fiberglassed the leading edge “D” tubes of all wings, the firewall area, and the balsa-sheeted components of the fuselage.
 
The framework was sprayed with white primer, to assist in the finish sanding steps, but also to prevent the wood grain etc. from showing through the semi-opaque covering. Balsarite adhesive goes on top of the primer, then Solartex Cub Yellow. Solartex is great to cover with – shrinks great around compound curves - but it needs the Balsarite to stick well to the wood framework. After the trim color has been applied (have not decided on the trim color or scheme, yet) the Solartex must be sealed with polyurethane or acrylic spray.
 
As shown in the photos, the weight is between 46 and 47 lbs; flying weight (dry) should be right at 50 lbs. The plans state the weight should be “48.87” lbs (my bathroom scale doesn’t give that level of precision). The plane now balances somewhat nose-heavy – that should even out after the fuselage is covered and the elevator servos are installed in the tail.
 
Specifications:
 
Genesis 33% Waco YMF-5
Current Weight: 47 lb (target weight = 50 lb)
Fuselage Length = 91 inches
Wingspan (Top) = 120 inches
Wing Area = 3,966 sq inches
Wing Loading = 26 oz/square foot (cub-like)
Engine: 3W 157XiB2 (17.7 HP)
Prop: 3W 32X10
Sullivan Skylite 7” wheels w. aluminum hubs
Hitec 5955TG servos (1 on each elevator, 1 on each aileron, 2 ganged for the rudder)
self-sdjusting servo tray for rudder
Futaba T12 FGA 2.4 GHz radio & receiver
Smart-Fly Power Expander MZ
Smart-Fly super switches
Fromeco Li-Ion batteries (2 @ 2400 for servos, 1 @ 4800 for ignition & smoke)
Sullivan Sky Writer smoke system

Update -- February 21, 2008 -- Update

  

I thought you might like to see photos of the new 3W "stump puller" being broken in for the Waco. manual for the 3W 157 recommends using a 32:1 mix of premium gas:ashless oil (I used Lawn Boy) to run the engine on a test stand at 2,000 to 2,500 RPM for 4 hours.
The photos show my Ozark "test stand". The new 3W ignition module can take the unregulated voltage from the Li-Ion battery pack.  The manual also recommends doing the break-in without any mufflers.
Well, I don't know how deep into the Black Forest them German boys have to go to do that type of unmuffled break-in, but I did find out that a 157 cc engine is REALLY LOUD without the mufflers, even at 2,000 RPM!
I tried it for <30 seconds, stopped the motor and put on the mufflers.

If that restricted the break-in, too damn bad! 

After the first 2 hours I adjusted the low end needle setting to get a reliable 1,200 RPM, and the high end needle was adjusted slightly rich to give 4,800 RPM.

After 3 hours I got a reliable idle at 1,000 RPM (really just putting along w/o loading up), and the high end -still slightly rich- gave 5,000 RPM.  Per instructions, did not leave it at peak for more than 10 seconds at a time. now has 4 hours and 2.5 gallons of bench time. Hand-starts easily with 2 to 3 flips, hot or cold. Transitions smoothly from idle to 5,100 RPM.

 Time to bolt it to the plane and finish the break-in while flying! am tentatively planning to test-fly the Waco in May.

 

  

  

  

  

 

 

Genesis 33% Waco Test Flight is a Success! 

After weeks of preparation and guestimating about the set-up for the 
test flight, the Waco YMF5 was flown successfully this Saturday 
morning (7/19/2008). This test flight was an all-out heart-pounding 
adrenaline rush! After hundreds of hours of building time and lots of 
$$$ invested, I hoped everything would go as smoothly as possible ? 
and it did go much better than I ever could have anticipated.

Prior to the test flight I was very concerned about the final weight 
of this airframe: 62 lbs empty! 68 lb with fuel! I built the plane 
pretty much according to plans with the materials provided, but I 
added 2 lbs by fiberglassing the leading edges of all wings as well as 
fiberglassing the center wing sections (1.2 oz cloth applied with 1 
coat of 50% thinned epoxy surfacing resin; no substitute for strength 
in the center sections!). I also added at least a pound by applying 
custom 2 mil vinyl graphics from Cajun R/C Specialties 
(www.cajunrc.com) ? take your time to apply them and they will look 
absolutely great!

The balance w/o fuel was perfectly horizontal when suspended at the CG 
point shown in the plans, but I wanted to have a little nose-down 
posture for the test flight. To achieve that, I removed the smoke 
system (pump, tank and tubing saved 14 oz of weight), moved all 
battery packs to just behind the firewall, and screwed 1.5 lb of lead 
weight to the front of the firewall. Now the plane ?balanced? with 
about 5 degrees nose down without fuel. It was definitively >10 
degrees nose-down when 48 oz of fuel was added. Perfect for a test 
flight: nose heavy is easier to control than tail heavy, except 
possibly during landings.

Based on previous experience with the flying characteristics of 
large-scale bipes (the Balsa USA 1/3rd scale Fokker DVII and Nieuport 
28C), I knew their flat-bottom wings cause these planes to climb 
steeply with full throttle. This is just like a full-size aircraft in 
which forward throttle = climb and back throttle = descent. HOWEVER, 
I?ve found that throttle-sensitive pitch adjustments are murder to 
decipher during a test flight ? the ballooning up with a nose-up 
attitude on takeoff plus the resulting apparent lack of ?elevator 
neutral? adds a lot of unneeded stress trying to control and trim out 
the airplane. The CURE is to put down thrust in the motor ? which is 
NOT called for in the Genesis plans or instructions. I added the 2 
degrees of right thrust which is called for in the instructions to 
offset engine torque, and then I decided to add about 2 degrees of 
down thrust by inserting washers as needed behind the engine mounts of 
the 3W-157XiB2. I also added about 1 degree of down trim to the 
elevator to help keep the nose down on takeoff, and 1 degree of right 
rudder + 1 degree of right aileron trim to counter the anticipated 
engine torque. Both of my Balsa USA bipes had needed down-thrust, down 
elevator trim, and right rudder + right aileron trim ? and I am 
absolutely certain the wing and stab incidences were built per plans & 
instructions. I used the Aileron-to-Rudder mix to add 23% rudder 
movement to assist the ailerons = about 1 inch of rudder deflection 
with full deflection of the ailerons (works great with the Balsa USA 
bipes). Ailerons were set with differential: 2 and ¼ inches up, 1 inch 
down at normal rate, add ½ inch to both at high rate (bipes often need 
as much aileron throw as you can get, and mixing in rudder helps to 
hold the tail up during a coordinated, slow aileron turn). Elevator 
was 2 inches up or down a normal rate, 2.5 inches both ways at high 
rate. Rudder is 4 inches each way with full deflection. All hinge gaps 
were sealed during covering. The radio is a brand new 2.4 GHz Futaba 
T12FGA, servos are all new HiTec HS5955TGs, Batteries include one 4800 
LiIon (ignition and smoke; full direct battery voltage to the 3W 
ignition module) and two 2400 LiIons thru two separate HD switches 
into a Smart-Fly SuperReg (set for 5.8 volts) and then into the 
receiver through a Smart-Fly PowerExpander 14MZ (constant voltage to 
the receiver, separate constant voltage to each servo). I added -20% 
expo to all controls (except throttle) to soften the midpoints.

Time to fly! New airframe, new engine, new radio! Major adrenaline 
rush ? I truly regretted the 3 cups of coffee consumed earlier. And it 
was hot and humid by 11 AM ? tough to keep the sweat out of my eyes. 
What a wonderful hobby ? where else can we get this type of 
heart-pounding excitement? The engine had a 3W 32 x 10 inch wood prop, 
a 4.5 inch MPI spinner, and it had been ?stump-run? with 3 gallons of 
32:1 gas. It idled reliably at 900 rpm, throttled up to a peak of 
5,200 rpm, and had a smooth, effortless transition between idle and 
full throttle. I set the low-end idle to 1,100 rpm and the high end 
was set slightly rich at 5,100 rpm. Range check with the engine on had 
been performed previously at home according to the Futaba?s manual ? 
excellent!

Taxi tests were surprising for such a heavy airframe. Ground handling 
was superb ? just like a big trainer. A few test runs down the runway 
showed that the tail comes up smoothly at about 25% throttle, and the 
mains lifted about an inch from the runway at about 33 to 50% throttle 
? I quickly throttled back and ?landed?. Taxied back to retighten the 
flying wires and prop bolts. All looked OK. The wind direction and 
speed were unsettled, gusting at about 5 to 10 mph ? mainly directly 
down the runway from the south, but occasionally coming from due west.

Waited for wind directly down the runway from the south, and slowly 
advanced the throttle. The takeoff roll was perfect, liftoff was at 
about 50% throttle, and climbout was effortless at 100% throttle. I 
had too much down trim in the elevator ? required several circuits 
around the field to add lots of up-trim and stop fighting the tendency 
for the nose to drop. Also too much right rudder and aileron trim ? by 
about half. Eventually I had the plane trimmed out for effortless, 
hands-off straight-and-level flight at about 50% to 66% throttle ? and 
it was not pitch-sensitive as I varied the throttle between 30% and 
100%; down-thrust does work!

The Waco flew very scale-like at 50% throttle. It undoubtedly will be 
faster and aerobatic at 100% throttle ? but I did not try loops or 
rolls, and flew mostly at 50% throttle. It climbs quickly at 100% 
throttle and a slight amount of up-pressure on the elevator stick. 
Definitely need to reduce the elevator throw and/or add more expo to 
the elevator because pitch/elevator control was VERY sensitive. 
Aileron turns were authoritative with perfect rudder mixing. The 
rudder mix kept the tail up perfectly during slow speed majestic 
aileron turns. I won?t change any of that!

I flew about 20 circuits around the field at 200? altitude with my 
fingers and knees shaking badly ? in anticipation of the landing. 
While up high I throttled back to check the stall speed. The nose 
lifted a little (too much down-thrust?) and it slowed down but kept 
flying at a nice landing speed into the wind. TIME TO LAND. How can we 
possibly expect to land a 65 lb airplane without disaster? Will it 
slow down too quickly, stall and fall out of the sky like a brick? 
Will I have to come in hot, fly it onto the runway and risk ripping 
out the mains? HERE GOES! I felt a nice 10 mph breeze coming directly 
down the runway from the south. Throttled back on the downwind leg to 
about 30% throttle at about 100? altitude, used the ailerons to make a 
nice nose down sweeping base turn toward the north end of the runway, 
leveled out into the wind and pulled the throttle back to landing-idle 
at about 75? altitude. OOPS ? the nose went up! We absolutely DO NOT 
want to be low and slow with the nose up! Pushed the nose down with 
the elevator, and the plane entered a nice gentle descent with full 
rudder authority to keep it in the middle of the runway. At about 1 
foot off the runway I flared to a perfect slow-speed touchdown (maybe 
15 to 20 mph?) on the main gear. The tail wheel dropped instantly, the 
plane did not bounce, and then the Waco simply rolled about 10 feed in 
the grass and came to a stop. What absolutely great slow-speed 
characteristics ? I had authoritative elevator, aileron and rudder 
control all the way to touchdown. What a nice handling aircraft!

It took about 30 minutes to stop shaking and burn off the adrenaline. 
No doubt about it - as the folks at Genesis say, this Waco FLIES LIKE 
A BIG GLORIFIED CUB. The 3W 157 is more than enough power for my 
flying style. Decisions: decrease the elevator throw, slightly 
decrease the down-thrust; and, take at least a half-pound of lead off 
of the firewall? Time to see about getting this plane certified for AMA.

Some photos are attached - enjoy!

Bob Wideman
AMA 620650
IMAA 26405
rwideman@uark.edu