View Single Post
  #24  
Old February 12th 06, 06:35 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Chuck Beeson and his Texas Chuckbirds


Reproduced (with permission) from Experimenter magazine.

Chuck Beeson and his Texan Chuckbirds

by Dick Cavin
June 1988

Unless you attended the EAA South-west Regional Fly-In at
Kerrville, Texas the past six years you have probably never heard of
Chuck Beeson and his ultralight-type Texan Chuckbirds. One of the
reasons for this dearth of publicity was that Chuck simply wasn't
ready for the spotlight.

Chuck is a rugged individualist. He has
spent 35 of his 52 years in aviation as a pilot and A&P. His
childhood years were spent designing and building models. In addition
to over a couple of dozen J-35, Champs and the like that he has
completely restored from bare bones, he has designed and built 29
airplanes in the ultralight weight class (or just beyond).

Of that 29, no two are exactly alike. Before ultralights came on the
scene, Chuck busied himself with the building of seven Pietenpols!
One was powered with a Chevrolet Vega engine conversion, effectively
Making it a single place with its overly heavy engine. Most of his 29
flyweights have been parasol monoplanes, but there were six biplanes
of varying configuration, one low-wing and six two-placers. In every
case except one, Chuck has designed, built and flown each airplane
(for several hours at least) before selling them to local pilots who
had the experience to take care of themselves and their airplanes.
Fourteen of them are still flying regularly from a grass roots style
airpark in suburban San Antonio where all are based. Others are
spread out over Texas. Some of the first airplanes didn't quite suit
Chuck, so he would take them apart and make a modification to correct
the deficiency, sometimes building a new fuselage, wing, or tail
group. Sometimes it meant building a new aileron, or perhaps putting
a new engine or prop on, but always it was experiment, experiment and
perfect, improving each model a little from the last one in an
ongoing evolutionary process.

Not only has Chuck had the opportunity to experiment and improve on
various airframes, but he has also evaluated several engines. In
addition to the popular Rotaxes he has tried three Zenoah engine
models and most recently the Subaru. He has also used Continental
A-65s in a couple of models, but removed them in favor of the two
cycle engines because the lighter weight two cycles give improved
performance. With their gear boxes the torque of the two cycles was
multiplied so that their thrust was as good or better than the A-65,
even though their horsepower was less. Chuck favors the Zenoah 40 hp
liquid cooled engine for his parasol kits. He has several of them
flying with this engine and four of them have gone over 400 hours
with only plug changes and no other problems. Not only are they
light, but they're also cheap, since they are a surplus engine 10,000
were on the market at one time. Combined with a Rotax 2.58:1 gearbox
and a Tennessee 60" x 28" wood prop, the Zenoah engine
makes a dependable powerplant package that's hard to beat for thrust,
weight . . . and cost. It also is a very smooth running engine from
idle rpm to full power. Chuck originally used the two-cylinder
opposed Zenoah that was air cooled, but after three over-temperature
seizures he said, "Enough is enough", and went to liquid-cooled Zenoahs
in the 40 and 50 hp range.

He is exceptionally pleased with the Subaru engine, too, having flown
it on his latest parasol and a new biplane prototype, which features a
swept upper wing for ease of entry to the cockpit. Not only is it smooth
as silk, it is super easy to start. He has flown it direct drive and with a
cog belt speed reduction unit that machinist friend Tom Arnold made
for it. Presently Chuck leans toward the direct drive unit, as the
excess of horsepower and low wing loading give him adequate take off
and climb performance and better cruise. For those tiny fields,
though, the increased thrust from the belt drive reduction is the
logical choice. It will pull a healthy static thrust of 287 lbs., so
this will also be a plus factor for high altitude take offs.

Chuck's philosophy towards kit purchasers is to eliminate every
material or process that demands much in the way of skills, tools,
and time for the first-time builder. Of course, the builder will
still have to complete over 51 percent of the work if the aircraft is
to be registered in the experimental amateur built category, which
most certainly will. The simplicity and straightforwardness of
Chuck's basic design not only reduces the required hours of building
for the beginner, but also does the same thing at the manufacturing
level. Chuck says he has been able to eliminate about 100 man hours
of labor with his progressive design refinements. /P
P ALIGN=JUSTIFY
This philosophy dictates the use of extruded aluminum angle for the
fuselage structure, which not only is lighter, but also is actually
stronger than a welded steel tube structure. He uses 3/4 inch x 1/8
inch 6061 T-6 angle for the basic fuselage structure, with larger
one-inch by one-inch by 1/8 inch angle used in concentrated load
areas. It is joined together with regular 1/8 inch universal head
solid AN rivets (not pop rivets) with two rivets per joint minimum.
How strong is the fuselage? With it supported on both ends, Chuck
loaded fifteen 80 lb. sacks of cement in the middle of the fuselage
(1200 lbs. total) without measurable deflection. Rotating it 90
degrees produced the same result. If one supports a soda straw at
each end it doesn't take much pressure to collapse it in the middle,
while an angle is much more resistant to buckling, explained Chuck.
While welded steel tube structures may be adequate in strength for
the loads imposed on them in service, there is no comparison in the
required building time.

Chuck says he can easily build a fuselage in two days, using simple
table top assembly jigs, while a welded structure would require five
to eight times as many man hours. Besides costing more in labor and
materials, the steel tube structure would still be subject to rust
and corrosion. If stringers are added for shape it would also mean
welding stub tubes with angle fittings, where on the aluminum
structure it only means a simple angle clip to be riveted on. Basic
fuselage weight is a svelte 24 lbs. In his basic "no
weldment" concept Chuck only uses one welded assembly - at the
apex of each landing gear vee, as it is tied to the axle and center
strut with 1/4 inch AN bolts. Even the engine mount uses the heavier
one-inch by one-inch by 1/8 inch extruded angles, again bolted with
AN bolts. Here he uses two parallel angles per side, running fore and
aft, and separated with two Lord mounts per side. These in turn are
attached to bracing vees that tie them to the fuselage structure via
bolts.

The landing gear is strictly J-3, with shock cord on each center
strut absorbing landing loads. For simplicity, Chuck uses a single
curved tube (instead of a vee) to feed loads from the shock cord
units into the transverse double angles that also pick up compression
loads from the front vee strut on the side. These double angles are
in parallel, with the tube in between secured with a bolt that ties
all three pieces together. This also permits some rotational movement
of the vee struts at their top end. Wheels are 5 inch plastic go-kart
wheels. No brakes are used on the ultralight version. Wherever
aluminum tubing is used on the airplane Chuck ties it into the
fuselage structure with either angles or flat straps on each side of
the tube and secures it with bolts.

In higher load areas, such as attachment points of the lift struts to
the fuselage, he uses one or more doubler tubes of .058 wall inside
the outer tube the last six inches. At the other end where these
1-3/8 inch by .035 lift struts tie to the 2 inch by .049 tubular
spars he uses two .090 stainless steel plates on each side, slightly
joggled to mate with both tube diameters, again using 1/4 inch bolts
through the neutral axis of both the spars and lift struts. The jury
struts are one inch by .049 inch tubing, tied to the spars and lift
struts with stainless steel straps that go over and under the tubes
and are blind riveted. Chuck originally had vee type lift struts
(like a J-3) on his first one, but removed them and went to parallel
struts when he found the arrangement too flexible with the pylon type
cabane he uses. To pick up drag loads he supplemented the lift struts
with 3/32 aircraft cable in an "X" configuration between
the struts, which also picks up torsion loads at the outer strut
attach Points.

Chuck has used two different wing spans in his parasols. The kit
model has a 26 ft. span, while some earlier models had a 22 ft. span.
Chord is four feet on either. Wing area is 104 square feet on the kit
airplane. With empty weights of 240 to 250 lbs and an average payload
of 210 lbs. (five gallons of fuel and an 180 lb. pilot) the wing
loading is a modest 4.42 lbs per square foot. This translates to a
"stall" speed of about 20 mph. The airfoil Chuck uses is
his modification of a Clark Y. This gives a 14 percent thick wing
section. Ribs are all 1/2 inch Klegecell polyvinyl foam and are cut
to shape on a high speed router. Each rib takes only seconds to make
, he says, and requires no edge sanding. There are no compression
struts in the wing, as each rib has a two inch wide bent up C channel
of .025 glued alongside the rib to take compression loads. This
channel also serves to attach the ribs to the spars at each end via
blind rivets. There is a single one-inch by .049 inch drag strut
inside the wing that runs from the root end to a point about four
feet outboard.

The aileron is also simplicity itself. It is a bent up piece of .020
aluminum that is pop riveted to the 1.5 inch x .035 inch tubular
spar, top and bottom. Three piano hinges are used per side and
attached via five pop rivets and epoxy adhesive to the wing's rear
spar. Ailerons are full span and have a formed rib at each end. At
the customer's option he can have full span ailerons, half span
ailerons with half span flaps, or full span flaperons. Ailerons are
operated via push-pull tubes with self-aligning bearings that run
from a fitting at the root end of the aileron to a bellcrank at the
aft end of the stick's torque tube. No differential throw is built
in, but Chuck says that like most ultralights you have to lead turn
entry with the rudder anyway, so adverse yaw isn't a problem. With
3-1/2 degrees of dihedral and the generously sized rudder the pilot
can quite easily pick up a low wing with rudder alone.

The Chuckbird's cabane is basically a pylon where wings are attached
without a center section, thus eliminating eight fittings in the
process. The vertical cabane struts are one inch by .058 inch tubes,
which are attached to the fuselage structure with 1/8 inch thick
straps and four bolts. Coming together at the top, heavy angles in
the horizontal plane on the fore and aft sides provide a secure
attachment for the wing spars. Spars are clamped in position and
match drilled. Parallel heavy angles run fore and aft on each side of
the cabane tubes and are bolted to them and the attach angles,
closing the force box. A 1/8 inch drag strap runs diagonally forward
and down from the spar attach point to further stiffen the pylon fore
and aft.

The parasol fuselage is 16 ft. long from nose to trailing edge of the
rudder. The cockpit width is 19 inches, which would be tight in a
closed version, but since it is a fresh air machine there is no
restriction to a person's shoulders, so it is quite comfortable for
even large pilots. Entrance and egress is easy, since the upper
longeron is low enough to step over easily. Head room looks to be
adequate for even a seven footer. The canvas seat is unique. It is
adjustable fore and aft and is so designed that a person's tailbone
never comes in contact with a cross tube. Visibility over the nose is
excellent, especially since the cowling narrows down to slightly over
a foot in width at the front. The control stick is a husky one inch
by .058 inch tube, as is the torque tube. One-eighth-inch straps are
bolted to the bottom of the stick for the proper gear ratio to the
elevators, giving generous flare power at the 20 mph landing speed
without undue sensitivity at cruise. Eyebolts through the stick are
used to attach swaged ends of the 3/32 inch control cables. Teflon
bearings support the torque tube at both ends. Rudder pedals are bent
up .090 aluminum and are piano hinged to the floor. The floor itself
is a beefy sheet of .040 2024 T-3. It is riveted to the parallel
one-inch angles crossing under the fuselage at the front and rear
spar attach points, transferring the higher loads of the lift struts
and landing gear to the fuselage structure, giving a "wider
footprint" to load paths.

The five-gallon tank sits forward of the instrument panel and is an
off-the- shelf PVC snowmobile tank. There is a half-round shaped
piece of .020 over it that is pop riveted to a 1/2 inch tube at the
top of the firewall. The cowling itself is all metal and attached to
the firewall top and bottom and to a 1/8 inch by 1/2 inch strip
standing away from the sides for engine air exit. Even though the
engine is liquid cooled and the radiator is hung below the firewall a
generously sized opening in the front of the cowl is a big help in
keeping engine temperature well within bounds on those blistering
95-100 degree Texas summer days (a big plus in engine reliability).
The tail group is built from one inch by .049 tubes, with the curved
ends made in a forming jig. The stabilizer/elevator spans 8 ft. The
elevator spar is one inch by .058 inch, while other tubes are one
inch by .049 inch. Formed .020 aluminum ribs give shape between the
tubes. Two double eyebolts are used for each elevator hinge. Bracing
is via a 3/32 inch cable that ties horizontal and vertical tail spars
together. No turubuckles are used on any part of the airframe, thus
saving 15-20 lbs. of weight and at about $15.00 each, it saves
significant money, too. Chuck uses a simple trick to tauten the
cables. He uses "master" cable with a turubuckle to make up
a finished cable. With a "tang" fitting and a long bolt he
can pull them up tight. Slick!

Chuck uses Stits HS90X fabric for covering the entire airplane,
attaching it to the ribs and other structure with Super Seam
adhesive. He likes Stits because the warp and woof weave are equal, a
help in heat shrinking. The turtle deck uses Klegecell formers and
one inch x 1/4 inch wood stringers and he attaches the fabric to it
in the same manner, so no rib stitching is used on the entire
airplane, making the 100-hour building time from the kit a reasonable
figure.

After taking in all these top flight construction details, would you
believe that Chuck has built all of these 29 airplanes without ever
drawing a single line of plans? He has done it all from what was
stored in his memory and from experience! They have all flown well,
but the latest parasol flies the best yet, he says. Chuck's
philosophy on kitting an airplane is on the conservative side. He
thinks it is wrong for someone to build a prototype and then
immediately start selling plans and kits. His airplanes have now
accumulated well over 3000 hours with no structural problems, so he
now feels he is safe in offering it in kit form. Even so he has hired
a consulting engineering firm to do a computer verification of the
structure. They do corroborate his static tests of a + 3.5 and -1-1/2
G loading. On one wing test to 3.5 Gs the spars were deflected 18
inches before the load was released, and they returned to position
without any permanent set. The engineers are also drawing up an
excellent set of (dimensionless) assembly drawings to guide the new
builder. He will also do a step-by-step video of the entire building
process for each kit purchaser. The video will include the final
covering of the wing and fuselage, plus rigging and test flying. You
might well ask what Chuck's next kit will be. It might be his new
Subaru powered biplane - after sufficient testing. He is now building
his version of a 1909 Bleriot just for the fun of it, something he
values highly.

Because he treasures the joy of sport flying around the
grass-root-type airports, he doesn't want to greatly expand his
production and be saddled with all kinds of big business money
worries. He just wants to make still another RHLA (Real Honest Light
Airplane) available for the average guy who wants to fly. Chuck
prices the parasol airframe kit at $3995, which includes everything
aft of the firewall except instruments, dope or glue. He will furnish
a firewall forward kit for $1,000, which includes the water cooled 40
hp Zenoah, muffler, cowling, engine mount and propeller. He will
continue to build the ultralight version, ready to fly, for $6995 for
those who have no place or time to build. All hardware is AN quality.
I think it is safe to say that we'll be seeing Chuckbirds in a good
many other parts of the country as their reputation spreads.