the
Barrows Bearhawk
by Budd Davisson, courtesy of
www.airbum.com
In recent
years we've seen utility come to the
fore in many of the new kit designs.
However, with a few exceptions, all of
the offerings have defined utility as
being two-people carrying only what
they need to get by. This utility has
also been available only in kits, so
the price of entry is daunting to
some.
And then there is
Bob Barrow's scratch-built, plans
offering, the Bearhawk. Bob defines
Utility as an airplane with few
limitations in the way it is used.
This includes four full-sized seats
(the cabin is the same size as a
C-172), 1200 pounds useful load, 55
gallons of fuel standard, and the
ability to hang anything from 150 to
260 hp in front of the firewall. Now
that's a usable airplane.
Barrow's airplane
is also unique in today's homebuilt
environment, where the predominant
thought pattern seems to be
build-it-fast-and-don't-worry-about-the-cost,
because a) it is only available as
plans and b) it emphasizes simplicity
and low cost.
The cost
of entry required to build Bob's
130-150 mph,
carry-anything-and-land-anywhere
airplane is the two hundred bucks for
the plans. Past that, you can spend as
much as you like, when you like, as
fast as you like. That's the beauty of
scratch built airplanes. You can spend
a couple hundred bucks on aluminium
and start hammering out ribs, or drop
a much larger bundle for the entire
bill of materials, which in the
Bearhawks' case is estimated at under
$6,000, which includes everything (as
in everything!) with only the engine
and prop to be add.
Bob did not start
out to design an airplane to sell. In
fact, the Bearhawk was originally a
project meant to fill his own needs
for utility in his airframe and engine
building business. But, we're getting
ahead of ourselves.
First, it is
necessary to understand Bob Barrows
and how he came to be sitting under
his airplane at Oshkosh answering a
million questions about his obviously
useful airplane.
Bob has been a
practicing mechanical engineer for
nearly thirty years which included a
long stint as Manager of Engineering
for one of Ingersoll-Rand's facilities
in Virginia. However, that was only
one part of his dual life. Outside the
office, he had developed his own
little airport, where he built
airplanes and re-built engines.
Initially, he built
a Midget Mustang, then designed and
built his own STOL, single place bird
he called the "Grasshopper." He flew
that for 15 years before parting with
it. Then there was a 260 hp,
symmetrical-everything, Pitts type
aerobatic machine. And an RV-3. And a
couple of rebuilt projects.
By 1980
his engine business was picking up and
he began to feel the need for a
utility type airplane and he began
work on what he then called the RB-4,
which was renamed Bearhawk.
"I got some parts
finished, spars and ribs and such, but
then I decided I needed a four-place
airplane for the business right then
and bought a rag-wing, Cessna 170
project."
The Bearhawk
languished in the backwaters of his
project ladened shop until he decided
to leave Ingersoll and strike out
freelance in 1988.
"My engine business
was doing well, so I wasn't afraid of
being out there on my own."
Confident words
from a man with a wife and four kids.
It was at that
point he decided to finish the
Bearhawk which took "...oh, I don't
know, a year or two..." He acts as if
building an airplane is a monthly
occurrence on his little strip.
Which
brings us up to Oshkosh '95, by which
time he had been using the airplane
for several years in his business. Bob
makes no bones about the fact that his
airplane is a working airplane. Not a
show winner or a machine designed to
blaze cross country in formation with
the composite crowd. However, whenever
we walked past the airplane on the
flight line, there was always a number
of folks asking questions or hanging
their heads down in the cockpit to see
how this or that was done.
The airplane was of
interest to a lot of people because it
was an airplane that makes a lot of
sense. Which is exactly the reason I
was attracted to it. It makes so much
sense in so many different ways.
Bob is one of the
friendly, more soft spoken types
you'll find and was quick to agree to
a flight. He is also just looking for
an excuse to go flying.
While we were
waiting to pull out from the flight
line, I spent some time looking the
airplane over. The wings are all
aluminium and many of the details,
Barrows is quick to point out, lean
heavily on Midget Mustang/RV
technology. This is especially evident
in the spars, which are "C" shaped
.032" channels with 1/8" x 1 1/4"
straps of varying lengths riveted to
the web face inside the flanges. The
straps are stacked in varying depths
and lengths depending on the stresses
and are centred on the outer strut
attach point rather than all eminating
from the root as with cantilever
designs.
The flaps and
ailerons are all aluminium framing
with fabric cover and hang from the
rear spar, which Barrows says is
heavier than normal for that reason.
The ailerons hang on long, tubing
weldments which form tripods bolted to
the rear spar. The flaps, which extend
all the way out to 50°, are simple
hinged affairs. Bob says he considered
Fowlers but opted for hinged flaps
because of their simplicity and small
trim change when deployed.
The ribs are all
hand formed over wood forming blocks
with no stretching done. Instead, they
are partially bent over the forms,
then the flanges hammered to 90° while
off the form. The resulting distortion
in the rib is removed by fluting the
flange between the rivets.
The entire control
system, elevator and flaps included,
uses cables and pulleys rather than
push rods, although bellcranks do move
short pushrods to activate the
ailerons. The bellcranks and final
pulleys mount on steel tubing
weldments bolted between the spars.
The 33
foot wings are skinned in .025"
aluminium and use bucked or squeezed
solid rivets throughout.
The struts are
aluminium and Bob says the best source
for them is damaged 180/182 Cessnas.
His are four inches shorter so struts
with broken forks can be salvaged and
used.
The fuselage is
good, old-fashioned steel tube, which
Bob used for a reason.
"From an
engineering standpoint, steel tube is
easy to analyze and the calculations
are reliable," Bob explains. "It also
offers excellent protection in case of
an accident and is easy for the
homebuilder to build with a minimum of
tools and jigs."
In reviewing the
plans, I found nothing in the fuselage
that was even remotely difficult or
unusual. In fact, the main wing
fittings nest a "U" shaped fitting
inside the usual blade-type fitting
which not only gives additional area
for bearing strength without welding
across the load path, but gives a huge
amount of weld length so the quality
of the weld becomes less critical.
There is a lot of this kind of thought
through out the airplane.
Because the
fuselage changes cross sectional shape
quite often, it looks as if it is
going to be one of those fuselages in
which the top and bottom trusses are
built first, then jigged into position
and the side pieces added.
The most complex
pieces, actually the only complex
pieces, are the Maul-type oil-spring
shocks in the landing gear. Those will
require a little machine work but the
result is an aerodynamically clean
shock system which doesn't take up any
cockpit space.
When the cowling is
opened the first thing you'll notice
is the huge amount of space behind the
engine. There's at least a foot of
empty space! But, when there's a 260
Lyc under the hood, that's where the
extra set of cylinders go. The
propeller stays in the same position,
so the cowing remains unchanged
regardless of which engine is used.
The only changes necessary are putting
the battery behind the huge baggage
compartment rather than on the
firewall.
The nose bowl,
incidentally, is a Pitts Special unit.
When poking around
under the hood on Bob's personal
Bearhawk, you'll also notice there is
no starter or alternator. One of his
friends says Barrows is allergic to
electricity.
When we finally
found ourselves out on the taxiway and
saddling up and I was delighted at his
door arrangement. First of all, there
is a door on both sides and the bottom
half hinges forward, while the top
half is hinged to the bottom of the
wing like a Cub. This makes it
practical to taxi or fly with the
windows open and your elbows on the
door sill like you were cruising the
drive-in on a Saturday night.
The cabin is also
extremely tall and full of light,
rather than being dark and crowded
feeling. The seating position is very
Cessna in its approach, a fact which
allows the builder to use a modified
Cessna 172 windshield on the Bearhawk.
Both the front and back seat room is
the same as the Cessna 172.
Bob has no seats in
his drawings, but adapts existing
seats and tracks to his airframe. His
machine uses Tri-pacer seats.
If I had
a complaint with the airplane it was
having to fly on the left side with a
right hand throttle. Yeah, I know, you
should be able to fly either way, but
having a control stick in the left
hand and a throttle in the right just
doesn't seem right.
In taxiing, a
slight stretch lets you see completely
over the nose, which isn't really
necessary but makes it nice,
nonetheless. A little brake was
necessary for taxi because the
tailwheel springs were extremely
loose.
I glanced up at the
trim, which is a Cessna-type wheel
mounted in the ceiling, satisfied
myself it was where Bob recommended,
and started the throttle in. The
engine in Bob's airplane is an 0-360
set up for mo-gas which he figures
gives about 170 hp. As the throttle
went in and the constant speed prop
began biting in, the airplane
literally lunged forward. I'm a real
fan of machines that start pumping
adrenaline right from the starting
line and this is one of them. What a
delightful monster this thing would be
with 260 hp!
Bob recommended
that I don't force the tail up but let
it come up on its own, which worked
nicely and almost as soon as it was
up, the airplane left the ground.
Actually, it didn't just "leave" the
ground. That's too simplistic. It
acted as if the landing gear and the
ground were like-poles on magnets and
the airplane was repelled away, it
separated so cleanly. The takeoff
happens so quickly, there's little or
no time to analyze what it is doing
directionally. But whatever it was
doing took only a tap here and there
to keep the centreline where it should
be.
Considering that we
were in a four-place airplane, the
initial rate of climb was almost
startling. It immediately started up
at around 1,300 fpm. With a 180 hp
engine the powerloading at gross would
be about 12.8 lb/hp which is quite
respectable but with a 260 hp, it
would be 8.8 lb/hp which puts it in
the skyrocket category. With two
people and half fuel, it would be
around 6.5 lb/hp which is right up
there with the serious aerobatic
specials. What a kick that would be!
We arrived at 4,000
feet in nothing flat and I put the
nose down setting up a 23 square
cruise which eventually settled out at
about 120 knots, or 135-138 mph. Which
brings us to one of the points I liked
best about the airplane: It is ready
made for doing all sorts of little
homebrewed mods, beginning with
milking more speed out of it. The
wheels and brake assemblies could be
faired and an easy 3-5 mph added.
Strut fairings and control surface
seals might be another 3 mph. Engine
cooling another few knots.
The airplane's lines are quite clean
to begin but Bob's goal was utility,
not speed. Still, the homebuilder
could do little clean-ups here and
there and net at least 8-10 mph at
cruise. With the bigger engines there
is no reason this thing shouldn't be
cruising at 155-160 mph, or even
higher, at altitude.
In cruise the
visibility is tremendous. The nose is
well down and the glass area is just
about right for maximum vis. Those who
are heavy into bush flying or sight
seeing might want to skin the doors in
Plexi.
The aileron
pressures are Cessna/Piper-average
with a reasonable break-out forces and
the roll rate is probably about
70-80°/sec, which isn't lightning
fast, but about what you'd expect for
an airplane of this type. I'd be
tempted to gap seal the ailerons for
increased rate and either go for
spades or move the aileron hinge point
back a little to lighten them up.
Don't construe this to mean the
ailerons are heavy, because they
aren't. It is just that my personal
taste is for lighter, quicker
ailerons.
As it is set up
now, the elevator is matched to the
ailerons but the rudder is relatively
light and tremendously powerful with
only a hint of break-out force, so
coordinating at first takes a little
practice to keep the ball in the
middle.
Even before we got
in the airplane Bob said he was still
experimenting with various details,
one of which was the stabilizer
setting. In doing stability tests we
found the airplane would begin to
return to neutral if pulled off trim
speed (statically positive) but then
it would begin to gain speed and
wouldn't level out as the speed built
up (dynamically neutral). We discussed
this in some detail and after Oshkosh,
Bob called to say he had changed the
stab setting by 2° and it had a marked
effect on the same tests. Now it was
dynamically positive and if pulled 10
knots off trim would gain less than 10
knots on the initial down line and
would damp out entirely with no
phugoid remaining in three cycles.
We wandered over to
an outlying grass field and set up to
shoot some landings. As I made the
first power reduction opposite the
end, the airplane's basic clean lines
were obvious in the way it held on to
its speed. It took more work than
you'd expect for an airplane of this
type to get down to the flap speed of
80 knots.
The first landing
was made with half flaps at an
approach of 60 knots which Bob says he
recommends for the first few landings,
although he's perfectly happy using 45
knots. The first landing was a
non-event because the airplane settled
on in an effortless three point and
rolled straight ahead for a short
distance before stopping on its own.
Then I started
playing with full flaps and lower
approach speeds and found it took a
little more technique. With 50° of
flap, the airplane is really nose
down, so with only two of us in the
airplane it was fun trying to get the
tail down at just the right moment.
Power-off with the CG that far
forward, there wasn't quite enough
elevator and I'd touch main gear first
with the expected hippity-hop. The
preferred approach would be slower,
with just a little power to keep the
elevator working.
When we were all
done flying and I was sitting around
with a Delta Charley (diet cola)
thinking about it, I found there was a
lot about the Bearhawk which I found
wildly attractive. In fact, given the
opportunity, I could actually see
myself building it. In the first
place, it's no secret I love bush-type
aircraft. So that's part of the
airplane's attraction.
I also love the
basic simplicity of the airplane and
Barrows straight ahead approach to
design. He doesn't complicate anything
and, because of that, it is easy to
see how things work and how to
fabricate them.
I was thumbing
through a couple of back issues of his
quarterly newsletter, Bear-Tracks, and
found yet another reason I like the
airplane: His straight-up design
approach is followed by a similar
philosophy in supporting his builders.
He doesn't waste a lot of time and
effort in designing brochures or fancy
graphics, he just gives the builder
totally understandable directions on
how to build things with a minimum of
tools. What he doesn't do in gloss and
colour, he more than makes up for in
clarity and understanding. The
newsletter presents a lot of neat
building tips.
The drawings
themselves are professional looking
blue-lines and show his background as
both an engineer and long-time
airplane builder.
And then there is
one of the other points about the
Bearhawk which is attractive: It is so
simple and well done that it makes a
flawless platform for someone who
wants to incorporate their own ideas
in cosmetics, streamlining, interior,
etc.
For those who are
afraid of doing their own welding
(shame on you): Bob reports several
manufacturing shops have contacted him
about building component parts for his
builders. So there is help out there
for the faint of heart.
We haven't had many
four place airplanes offered to the
homebuilder in the past and none have
caught on. The Bearhawk looks as if it
should change that trend. After all,
think about its name: It's a Cessna
Skyhawk in concept with the brawn and
attitude of a Bear. Bearhawk. What a
combination!
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