GP4

(Ron Benell) wrote:

Good morning all

I've just finished building a Hatz Classic biplane which I displayted
at Oshkosh this year and now need to start another project. I've
always had a eye for the GP4 and wonder if there is anyone out there
that has any experience with the airplane. Any structural failures,
resale values, etc etc.

I have wood building experience with a Super Emeraude some years ago
and I'm looking for a project that will take quite a few years to
complete. I just like the building process...

Any comments will be appreciated.

Thanks Ron


Ron,

Have you talked to Bernie Griffin yet? He was at Oshkosh this year
with his beautiful GP-4 and won Grand Champion Plans Built. There was
a feature article on his plane in the August, 2003 issue of Sport
Aviation. Of course, you could talk to George Pereira himself. His
email address is on his Osprey Aircraft website,
http://www.ospreyaircraft.com . There is a Yahoo GP-4 discussion
group at http://groups.yahoo.com/group/GP-4/ .

By the way folks, Ron was awarded an Outstanding Workmanship Plaque
this year at Oshkosh for his beautiful Hatz Classic. Here is a
picture of Ron's Hatz Classic,

http://www.AirplaneZone.com/Newsgrou...sc02506bSM.jpg

Ron and his Hatz were also featured in an article in "Airventure
Today", during the show. Here's a link to that article,

http://www.airventure.org/2003/friaug1/hatz.html

Nice plane Ron. Good luck with your GP-4 project.

David O -- http://www.AirplaneZone.com

"Ron Benell" wrote in message
m...

I have wood building experience with a Super Emeraude some years ago
and I'm looking for a project that will take quite a few years to
complete. I just like the building process...

Ron.........

May I ask which Emeraude you worked on?

Rich S.

(Ron Benell) wrote:

Good morning all

I've just finished building a Hatz Classic biplane which I displayted
at Oshkosh this year and now need to start another project. I've
always had a eye for the GP4 and wonder if there is anyone out there
that has any experience with the airplane. Any structural failures,
resale values, etc etc.

I have wood building experience with a Super Emeraude some years ago
and I'm looking for a project that will take quite a few years to
complete. I just like the building process...

Any comments will be appreciated.

Thanks Ron


Ron,

As a follow-up to my previous post, a search of the NTSB accident
database reveals that there have been three fatal GP-4 accidents
resulting in 5 fatalities. As there have only been a dozen or so GP-4
completions to date, this seems an unusually high percentage. Of
course, the accident reports themselves will tell a more complete
story. I'll let you draw your own conclusions. Here are the links to
the accident reports. Be sure to read the full narratives.

http://www.ntsb.gov/NTSB/brief.asp?e...11X12599&key=1

http://www.ntsb.gov/NTSB/brief.asp?e...12X18712&key=1

http://www.ntsb.gov/NTSB/brief.asp?e...06X00626&key=1


David O -- http://www.AirplaneZone.com

"Rich S." wrote in message ...
"Ron Benell" wrote in message
m...

I have wood building experience with a Super Emeraude some years ago
and I'm looking for a project that will take quite a few years to
complete. I just like the building process...

Ron.........

May I ask which Emeraude you worked on?

Rich S.

Rich

I worked on The CP328 Super Emeraude for a few years and at that time
just didn't have time to finish it. Since then I've retired and have
lots of time.

Ron

On Tue, 02 Sep 2003 15:35:50 -0400, David O
wrote:

(Ron Benell) wrote:

Good morning all

I've just finished building a Hatz Classic biplane which I displayted
at Oshkosh this year and now need to start another project. I've
always had a eye for the GP4 and wonder if there is anyone out there
that has any experience with the airplane. Any structural failures,
resale values, etc etc.

I have wood building experience with a Super Emeraude some years ago
and I'm looking for a project that will take quite a few years to
complete. I just like the building process...

Any comments will be appreciated.

Thanks Ron


Ron,

As a follow-up to my previous post, a search of the NTSB accident
database reveals that there have been three fatal GP-4 accidents
resulting in 5 fatalities. As there have only been a dozen or so GP-4
completions to date, this seems an unusually high percentage. Of
course, the accident reports themselves will tell a more complete
story. I'll let you draw your own conclusions. Here are the links to
the accident reports. Be sure to read the full narratives.

http://www.ntsb.gov/NTSB/brief.asp?e...11X12599&key=1

http://www.ntsb.gov/NTSB/brief.asp?e...12X18712&key=1

http://www.ntsb.gov/NTSB/brief.asp?e...06X00626&key=1

I have flown this one and can give a bit more background and detail.

As to the crash itself the ground had lots of fuel on it but that
evaporates quickly. Hence the blighted vegetation.

As the report noted, there were no baffles in the tanks. Although
the report stated ground scarring was limited to underneath the plane
form...The leading edge of the right wind left an imprint *forward of
the wing* that started at the root and extended forward about 8 inches
to a foot at the tip. This is consistent with the empennage being
"bent" to the left as seen from the rear looking forward.

As to the thumb pressure compression it's amazing as the cylinders and
a couple of accessories were the only things intact Even the crank
case was broken.

"The general consensus locally" is the plane was in a flat spin. This
caused the tanks to unport and the engine to sputter and quit. How he
got into the flat spin is even more conjecture. Again, knowing the
plane and pilot the best guess is something broke and he lost it
trying to put the gear down.

As to the plane itself.. "It's my understanding" that the wing had
been changed in cord as well as position to get the CG *within* a
useable range.

Roll forces were normal. Pitch forces were nonexistent. No breakout
force and no gradient. It felt like a game joystick with no springs.
It took _very_little stick movement fore and aft for substantial pitch
changes. You *positioned* the stick fore and aft for pitch changes.
I would put my hand on my knee and roll using my leg. Pitch was a tiny
movement between thumb and forefinger. Pitch *appeared* to be neutral.
Neither divergent or convergent. You put the nose in a position and it
stayed there. It was still *relatively* easy to fly.

When I flew it, the plane responded well. Yet there is that tiny
tail. As far as I know, and I'm almost certain, the pilot had no
aerobatic training, nor had I ever heard of him taking spin training.
I sneezed and it took two miles to stop the PIO. That was as much due
to my unfamiliarity with the plane as with the ultra sensitive pitch
control. I just opened my thumb and forefinger and the PIO stopped.
The Gs were moving my leg just enough to cause the stick to move a
tiny bit.

His aversion to aerobatics came from a botched attempt to do a loop in
the Barracuda many years ago when he was a relatively low time pilot.
This was also back in the days before a high
performance/complex/retract checkout was required..
The result scared him so bad he wanted nothing to do with aerobatics
even riding with an experienced pilot after that. Although... the air
show pilot surprised him with a roll in the Barracuda when he wasn't
expecting it. They described it as IFR *in* the cockpit. (I'm sure
that requires no explanation for most)

I do know he DID NOT like anything much other than the normal flight
regime. I started out with some dutch rolls, but didn't even make it
to 60 degrees when he said "that's enough". For all it's lack of
control harmony it had very little adverse yawh and as well as it
behaved I'd guess it would have easily gone to 90 degrees with a
hesitation. (He didn't even want to go back and get chutes to give it
a check out)

The plane had been test flown by at least one well know aerobatic
pilot from the air show circuit. However it was not a full checkout
and this particular aircraft had never been spun. I'm not so sure it
had ever been stalled with the exception of the aerobatic pilot and
I'm not positive he stalled it.

To complicate matters the gear down speed was relatively low...about
120 MPH as I recall, but I may be off on that number. However it was
slow for a plane that fast and slippery.

One note: On a trip to Sun 'n Fun one year, the elevator trim tab
broke which resulted in an immediate pitch up to 6Gs even with a very
rapid correction from the pilot...who was not the owner. That caused
the pilot to decide he really didn't want to keep flying it.

I'd not call this particular plane representative of the model, but
then again I'd not throw it out either. I'd like to fly a stock model
through the whole flight envelope, but definitely while wearing a
chute.

It was fun to fly, but certainly not for a low time pilot or even one
a bit rusty.

jack was a great guy who liked to experiment. Some of his experiments
worked great and some didn't. How much they may have contributed to
the end result is still open to debate.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)


David O -- http://www.AirplaneZone.com

(Ron Benell) wrote:

David

Thanks for the info. I've read the NTSB reports and find them quite interesting.

I'll need to do a little soul searching before I make my final decision.

Thanks again.


You are quite welcome, Ron.

David O -- http://www.AirplaneZone.com