Steve: My Benson was definitely not under powered. I had a ball type
airspeed indicator that as I recall topped out at 85. I stuck the ball all
the way up in the tube so far that I had to take a pipe cleaner and knock it
loose. I was never passed by any other gyro. At the time we figured that I
had done close to 100mph in straight and level flight. The Super Mac was
very light and under ideal conditions delivered 95hp. The engine mount was
raised some 2" to get the bigger prop installed. I can remember racing
another Benson that had a Super Mac but a smaller prop and a streamlined
body and I never saw them after I passed. The Benson manual recommended
taxiing without the rotor installed to get used to the steering. The first
time I did that I ground the wood front wheel brake almost in two and never
got the throttle much off idle. The thing felt like a dragster without the
rotor. After installing the rotor and getting it up to speed before taxiing
very far, the thing became much more controllable. As I recall the thrust
line on mine was just a couple of inches below my shoulders. Yeah if I was
cruising along at say 50 indicated and firewalled the throttle without some
aft cyclic, it would push my nose down a bit. I think that if I would have
had a side-by-side fuselage up front to provide additional drag as the nose
pitched forward, I might have had a different experience. I do remember
that once in a while doing those Brock spirals, (zero forward airspeed and
enough throttle to blow the tail around) the nose would sometimes get lower
and lower giving me the feeling it was going to try to split S. I never let
it get beyond about a 45 degree nose down before I stopped the spiral and
flew out.
Yep Vaneks bird looks pretty good and he can fly the thing. We have seen
his loop and roll and it is darned impressive. I've also seen him get off
the ground in a very short span. Take a look at the Magni in a front on
view with Greg Greminger on board. I know he weighs at least 250 and
imagine a passenger in the back. I can't believe that it is very close to a
CLT. The Magni does have a HS though and the tandem seating doesn't give a
real draggy front end.
I rode in the Sparrow Hawk prototype which has all the CLT/HS and found it
very stable but the control feel was monstrous. I had never flown anything
including a T-38 that had such heavy controls. Even the Bell 47 with the
hydraulics turned off didn't have such a heavy feel. Also the take-off roll
was as long as a Cessna 150 on a hot day.
--
Kathy Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell
www.vkss.com
www.experimentalhelo.com
"Steve R" wrote in message
...
"Stuart & Kathryn Fields" wrote in message
...
Steve: I know what you are talking about. We got into a controversy
when
we produced the PRA magazine for publishing a letter from Cdr. Wallis
outlining his opinions on the CLT and HS. I was kind of taken aback
with
all of the sudden inflammatory kinds of statements putting down the non
CLT/HS ships as I had never encountered any problem flying my Benson and
I
flew it in the desert turbulence and winds strong enough to allow
hovering
takeoffs. My wife flew the ship and she had only soloed a Piper Colt.
So
we had no experience to support the damning criticisms of the Non CLT/HS
ships. A conversation with Ken Brock trying to see if I had just lucked
out
and never experienced the close call in my Benson and he seemed to agree
more with Cdr. Wallis than the current PRA position. I tended to use
Ken
as
my expert on gyro things.
BTW, as I recall, we had to set my Super Mac up even higher than the
stock
Benson because I was driving a larger diameter prop. I also had the
outboard motor fuel tank that set below the seat. I'm sure that my
thrust
line was above the vertical c.g. with full fuel. The little rock guard
on
the Benson sure didn't qualify as a HS either.
I guess I was either luckier than the others, or a good gyro pilot, or
my
ship was somehow more stable than the others. I know for sure there
has
been oodles of opinions and calculations floating about supporting the
need
for CLT and HS. Now that I'm flying adefinitely unstable aircraft
(helo)
my
dog is not in the CLT/HS fight.
--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell
www.vkss.com
www.experimentalhelo.com
I understand what you're saying about the inflammatory attitudes of some
folks. As a very raw newbe in the PRA, some of them had me seriously
wondering if I really wanted to be involved in this group? It was very
difficult to figure out who to believe and who not too. I think it's
better
these days because there seems to be more of a consensus as to what's
appropriate in a pusher design and what's not. Back then, it seemed like
everyone had their own pet designs and very few folks ever agreed with
each
other! ;-)
On the subject of the Bensen you learned to fly! One thing I remember
reading about the original design that Mr. Bensen developed and flew was
that it was relatively underpowered and/or used a smaller diameter prop
than
most of the modern (the original Air Command comes to mind) gyros do. As
a
result, the early generation Bensen's were much closer to centerline
thrust
than the larger, stretched out versions that have come afterwards. Is
this
something you'd agree with? Also, you mention putting a "super mac" on
your
Bensen and having to raise the engine to accomodate a larger prop which
also, naturally enough, raised the engine's thrust line relative to the
aircrafts CG. Do you remember how far you had to raise the engine? Makes
me wonder if you were still under whatever magic number in thrust offset
that kept you in a safe zone. I know that machines like Jim Vanek's
SportCopter are not true centerline thrust designs but they seem to have
(from what I've read anyway) very favorable flight characteristics. It
makes me wonder if you simply didn't get far enough out of line for the
bad
characteristics to be a significant issue. Either way, I'm glad it worked
out for you. I'd appreciate any comments you care to make on that.
Thanks,
Steve R.