More VG Test results...

In the FWIW department....

Been "Playing" ....carefully..

Not very scientific, but thought I would share this anyway....

Our Warrior was light, 1/2 fuel, me alone (165 lbs) 60lbs in baggage
....

-6 Deg C,

Did some takeoffs using Mattisons procedure without the rolling
start...

45 mph, dropped 2 notches, counted "thousand 1, thousand 2", and
hauled back.. a LOT! (but not all the way, kind of timid yet)

When the flaps went down, the plane instantly popped up on the
struts...

When I rotated, the plane literally leaped off the rny! I had 50 AGL
in a few seconds..

The deck angle was scary!- but it kept on going....

NO WAY would I have been able to do that before..

Art says that if you do it properly, the stall warning horn should
emit a short beep at rotation, and the yoke should come ALL the way
back..

BTW, at this load, temp and 3000 ft agl, I was stalling at 40 knts
indicated with 40 degs of flap. Anyone have any formula to work out
the calibrated AS at that angle?

The POH (PA-28 151) leaves a bit to be desired here..

Interesting day....


Dave

I guess I missed something.... What is "Mattisons procedure"?

Steve Mills


On Tue, 02 Jan 2007 21:13:28 -0400, Dave
wrote:

In the FWIW department....

Been "Playing" ....carefully..

Not very scientific, but thought I would share this anyway....

Our Warrior was light, 1/2 fuel, me alone (165 lbs) 60lbs in baggage
...

-6 Deg C,

Did some takeoffs using Mattisons procedure without the rolling
start...

45 mph, dropped 2 notches, counted "thousand 1, thousand 2", and
hauled back.. a LOT! (but not all the way, kind of timid yet)

When the flaps went down, the plane instantly popped up on the
struts...

When I rotated, the plane literally leaped off the rny! I had 50 AGL
in a few seconds..

The deck angle was scary!- but it kept on going....

NO WAY would I have been able to do that before..

Art says that if you do it properly, the stall warning horn should
emit a short beep at rotation, and the yoke should come ALL the way
back..

BTW, at this load, temp and 3000 ft agl, I was stalling at 40 knts
indicated with 40 degs of flap. Anyone have any formula to work out
the calibrated AS at that angle?

The POH (PA-28 151) leaves a bit to be desired here..

Interesting day....


Dave

I think he's referring to Art Mattson's high performance take-off procedure
for Cherokees.

See http://www.pipermods.com/


"Stephen N Mills" wrote in message
...
I guess I missed something.... What is "Mattisons procedure"?

Steve Mills


On Tue, 02 Jan 2007 21:13:28 -0400, Dave
wrote:

In the FWIW department....

Been "Playing" ....carefully..

Not very scientific, but thought I would share this anyway....

Our Warrior was light, 1/2 fuel, me alone (165 lbs) 60lbs in baggage
...

-6 Deg C,

Did some takeoffs using Mattisons procedure without the rolling
start...

45 mph, dropped 2 notches, counted "thousand 1, thousand 2", and
hauled back.. a LOT! (but not all the way, kind of timid yet)

When the flaps went down, the plane instantly popped up on the
struts...

When I rotated, the plane literally leaped off the rny! I had 50 AGL
in a few seconds..

The deck angle was scary!- but it kept on going....

NO WAY would I have been able to do that before..

Art says that if you do it properly, the stall warning horn should
emit a short beep at rotation, and the yoke should come ALL the way
back..

BTW, at this load, temp and 3000 ft agl, I was stalling at 40 knts
indicated with 40 degs of flap. Anyone have any formula to work out
the calibrated AS at that angle?

The POH (PA-28 151) leaves a bit to be desired here..

Interesting day....


Dave

On Wed, 03 Jan 2007 14:24:15 GMT, "Steve Foley"
wrote in j0Pmh.2$5g.0@trndny01:

I think he's referring to Art Mattson's high performance take-off procedure
for Cherokees.

See http://www.pipermods.com/

Dave must have some information additional to that provided on the web
site, as is see no mention of moving the elevator to the stop at
rotation:


http://www.pipermods.com/shortfield.htm
Short Field Takeoff Procedure
Getting the best short field performance out of your Cherokee begins
before reaching the end of the runway. This requires leaning to
slightly rich of max. power at your runup. This is achieved by leaning
to maximum static RPM and then richening the mixture slightly as you
would at your cruise altitude. (If you plan to cruise more than 2000
AGL, you will need to further richen the mixture.)

Never stop on the end of the runway. After you are cleared for
takeoff, make a rolling turn onto the runway-no flaps. When you reach
an angle of 45 deg. to the runway, start accelerating so that by the
time you have completed your turn, you are at full throttle.
Accelerate to your predetermined rotation speed (this is between 45
and 60 mph depending on mods, temperature and loading), at this speed,
pull in 2 notches of flaps, count 1.... 2 and rotate! You can take
your first notch of flaps off fairly soon after gaining some speed and
take the second one out as you continue to gain speed.

This procedure is like adding 300ft+ to the runway which reduces your
"pucker factor" for clearing obstacles. Practice on a longer than
needed runway and get comfortable with it before doing it on a short
field. I use this procedure on all takeoffs regardless of runway
length, as I go into short grass strips regularly and want the
procedure to be second nature. By using ths [sic] procedure, you will
quickly discover that your Cherokee is capable of more than you
realized.

For a first-hand account of how well this works, read Jim Cavanaugh's
article from Pipers Magazine.

From Jim Cavanaugh's article from Pipers Magazine: (noted at the end of your
post)
"His technique is to accelerate the airplane to 45mph, quickly pull in two
notches of flap, count to two and pull the wheel back into your stomach. "



"Larry Dighera" wrote in message
...
On Wed, 03 Jan 2007 14:24:15 GMT, "Steve Foley"
wrote in j0Pmh.2$5g.0@trndny01:

I think he's referring to Art Mattson's high performance take-off
procedure
for Cherokees.

See http://www.pipermods.com/

Dave must have some information additional to that provided on the web
site, as is see no mention of moving the elevator to the stop at
rotation:


http://www.pipermods.com/shortfield.htm
Short Field Takeoff Procedure
Getting the best short field performance out of your Cherokee begins
before reaching the end of the runway. This requires leaning to
slightly rich of max. power at your runup. This is achieved by leaning
to maximum static RPM and then richening the mixture slightly as you
would at your cruise altitude. (If you plan to cruise more than 2000
AGL, you will need to further richen the mixture.)

Never stop on the end of the runway. After you are cleared for
takeoff, make a rolling turn onto the runway-no flaps. When you reach
an angle of 45 deg. to the runway, start accelerating so that by the
time you have completed your turn, you are at full throttle.
Accelerate to your predetermined rotation speed (this is between 45
and 60 mph depending on mods, temperature and loading), at this speed,
pull in 2 notches of flaps, count 1.... 2 and rotate! You can take
your first notch of flaps off fairly soon after gaining some speed and
take the second one out as you continue to gain speed.

This procedure is like adding 300ft+ to the runway which reduces your
"pucker factor" for clearing obstacles. Practice on a longer than
needed runway and get comfortable with it before doing it on a short
field. I use this procedure on all takeoffs regardless of runway
length, as I go into short grass strips regularly and want the
procedure to be second nature. By using ths [sic] procedure, you will
quickly discover that your Cherokee is capable of more than you
realized.

For a first-hand account of how well this works, read Jim Cavanaugh's
article from Pipers Magazine.

On Wed, 03 Jan 2007 15:39:56 GMT, "Steve Foley"
wrote in g7Qmh.5$Jf.4@trndny03:

From Jim Cavanaugh's article from Pipers Magazine: (noted at the end of your
post)
"His technique is to accelerate the airplane to 45mph, quickly pull in two
notches of flap, count to two and pull the wheel back into your stomach. "

I'd be more comfortable hauling back on the yoke like that if it were
possible to do try it at altitude. But I suppose, if you could
perform slow flight at 45 MPH, it would work fine in ground effect for
takeoff.

I wonder what it would take to produce new performance graphs for
modified aircraft? It would seem the FAA would require them to
certify the modification.


http://www.pipermods.com/SEATBELT.html

Technique by Mattson

The aircraft was not light with the fuel, Art and myself on board. We
held the door open until the runup was completed and only buttoned up
when we were ready to roll. I had asked Art to fly left seat and show
me his technique for a maximum performance takeoff. I contented myself
to sit there and watch his movements and the airspeed indicator as he
advanced the throttle and dance the pedals to keep us lined up and it
was quite a show.

With the VG’s, airflow over the Cherokees wings is greatly enhanced.
We had watched a video tape made by a physics teacher at Embry Riddle,
showing the stalled condition of the wing at various stations at low
airspeeds. I don’t know if Art has tuft tested the wing with his VG’s
installed, but it felt like angle of attack had been taken out of the
equation when he rotated and lifted off. His technique is to
accelerate the airplane to 45mph, quickly pull in two notches of flap,
count to two and pull the wheel back into your stomach. It is a very
daunting procedure from where I was setting.



But it worked! I couldn’t believe the deck angle as we sprang off the
ground. It was more like a Maule than a Cherokee. The entire takeoff
run had just been about 400-450 feet, and I would estimate that it was
just a second or two to 50 feet AGL. The book says the roll alone
would have taken 800 feet on a standard day, and another 900 feet to
clear the 50 foot obstacle. We had to have been flying out of another
book!

I quickly calculated that the fuel, Art and I weighed in at 570 lbs.,
roughly 280 lbs. less than the normal useful load, but still it was
about an 8,000 feet D.A. day!

Art held the climb for a bit, then let the airplane accelerate to
70mph and he raised a notch of flaps, then at 80 mph indicated he
cleaned up the airplane and we began to fly normally. The rest of the
climbout was at 85 mph and about 500 fpm.

Once at 3,000 feet MSL, we poured the coals to her and waited as the
noise level and airspeed raced each other to the max. It takes a lot
of time to overcome the inherent drag of an airframe, particularly one
that is not cleaned up much. Eventually, though, we settled in on a
steady 139 mph TAS and a veritable symphony of wind noise and engine
roar. A passing thought was that designers who don’t expect their
airplanes to go fast don’t do much to cancel out wind noise. Art needs
one more STC!

Coming back to the airport, Art demonstrated a short field landing
and with an approach at 70 mph, cutting back the throttle over the
fence, we quickly dropped in and touched down at about 47 mph, about 8
mph lower than the book. With judicious braking, not heavy, we were
able to stop in about 400 feet.



The Novice’s Turn

We next taxied back for my turn and from the right side I tried to
reproduce Art’s takeoff. It wasn’t bad, but I experienced what a lot
of his customers do: it doesn’t feel natural to be so abrupt in a
Cherokee. Art had told me of some of his customers complaining that
their takeoff performance doesn’t match his. He has questioned them
and flown with some and determined that most of the performance
complaints is due to their lack of aggression with the controls.

"They’ve got to trust the numbers," he told me, so I did. Still, it
felt funny forcing the airplane off the ground when all you’ve ever
heard and read about Cherokees tells you it can’t be done. I shot two
takeoffs like this before Art had me stop and let him out. He wanted
me to experience what the airplane would do when it was light. And it
was dramatic!

It may be difficult for some of you to get excited about a dowdy old
Cherokee. Its reputation is that it is about as exciting as a wild
night in Mayberry with Aunt Bea. True, it will never be a Cessna 185
or a Maule MX-7, but performance, as is thrill, is relative. I shot
three takeoffs solo and each was a little shorter and a little
steeper. Flying alone is simply fun. I have a tendency to be slightly
distracted when someone is with me, whether in an airplane or on the
golf course…anyplace where focus has an effect on your personal
performance level.

When we stopped for lunch, Art showed me the propeller that had been
on the airplane when Vince brought it to him. It was so far out of
tolerance that you didn’t even have to use a measuring device to see
it. The blades had been dressed so many times that they were very thin
and merely taking off and cruising had caused them to be bent forward.
I put a tape measure on it and one blade was an eighth of an inch
longer than the other, and the blade width was different on each end.
Sensenich has definite parameters for their props and this one just
needed a coat of paint to be a permanent wall decoration.



Gap Seal Installation

After lunch, Art , his son Scott and I cleaned the wings for the
installation of the gap seals. Vince had asked for the seals and Art
thought it would be a good time for me to fly the airplane before and
after. We didn’t have time to do a complete installation, since the
application time takes about an hour per control, so I had to fly it
with just the aileron gaps sealed. Art said that this is the most
important of the three.

Flying an airplane on the same day is a great way to get before and
after impressions. I was fortunate to be in the right place at the
right time. By this time, the fuel was down to about one-third, but it
was up to 96 degrees. Power up to 45…two notches…count to two and
pull. By now I was getting fairly comfortable with the routine and
noticed almost immediately how much smoother the roll force was. They
just felt more solid with the gap seals. I flew wing wobbles up to
3000 feet and left the throttle in all the way to see what happened to
the top end. Again I had to wait about 5 minutes. This seems like a
long time in cruise mode, but the result was an increase over the
earlier reading by 2 mph. Allowing for a few bumps, the needle on the
True Airspeed Indicator vacillated around 141 mph for so long that I
considered this new speed to be valid.

I headed back to the airport and decided to shoot one more takeoff.
It was too hot for any more of this foolishness, This time I got
cocky. I was feeling good and when I pulled her off I really pulled
her off. It was the only time I got the stall horn to honk and when I
got back, Art was grinning ear to ear. I guess I had nailed one!

Art and his assistant Will had been installing wheelpant on Art’s
personal airplane and it was time to take it up. This airplane has
always been slower than his first Cherokee. Whether rigging, tools
left by the builders or something else, it just hasn’t been able to
produce the good numbers. Art reasons it might be the design of the
aileron skins, which have the stiffening beads fabricated outward, as
opposed to the inward beads of his original plane. At least the
performance increase from stock to modified is the same in both, which
demonstrates the effectiveness of the mods, but Art has the speed bug
now and he can’t help but be disappointed.

The airplane has the prop mod, gap seals and VG’s and that is about
it at this point. He has decided to keep the engine in the 150 hp
configuration to aid in evaluating the different mods he has planned.
He admits that he had been bitten by the speed bug and went all out
for speed and not all his customers are interested in an engine mod.
He needs to know what each mod will do with a standard engine.



Difference in Takeoff Performance

Naturally, the takeoff performance is different. It was still light
years ahead of a standard Cherokee, because of the VG’s. With a stall
speed lowered by 8mph, you’re going to see a difference. At top end,
the airplane can achieve 135 mph, and normally cruises at 120mph and I
could feel Art’s frustration, since his first airplane had broken 180
mph over a dozen times under Sea Level conditions. On a more pragmatic
level, I realize that this is a test airplane and that each mod will
generate a performance change. Each of these will then be documented
against a known value. The speed will come later, as will the
increased horsepower, I’m sure. I asked Art to shoot a couple of
takeoffs for the camera, and the day was over.

"Larry Dighera" wrote in message
...
On Wed, 03 Jan 2007 15:39:56 GMT, "Steve Foley"
wrote in g7Qmh.5$Jf.4@trndny03:

I wonder what it would take to produce new performance graphs for
modified aircraft? It would seem the FAA would require them to
certify the modification.

They are not required for engine upgrades. That has certainly affected the
performance of my plane. I increased the HP from 150 to 160 and put on a
cruise prop (58" to 62"). I get similar takeoff performance as before, but
cruise much faster (relatively - it's still a fat-wing Cherokee)

Hi Larry!

Was not quoting Art here, although he mentioned to me verbally that he
has used full back yoke to rotate, especially with the heavier
engined cherokees and the "full fuel, 2 heavy front seat Pilot/pax
and no baggage" situation....

I had it well back, but have not hit the stop yet, and may never.

Apparently, if done to soon, the aircraft simply won't lift...

Although having spoken to several about this mod, I was only
slightly prepared for the result..

Now, remember, it was cold, slight head wind, and I was light.

Brakes held , full RPM, and let go....

I was well in the air at the 500 ft marker..

The deck angle was ...umm... "interesting" .

And the little Warrior just wanted to keep going up... no wobbles, no
stall warning, no buffeting, just the most rapid "up" I have ever
experienced with 150 horses...

Over a year ago. I got an E-mail from a straight wing Cherokee pilot
who indicated that these two mods are " the FIRST ones to spend money
on " when it comes to the Cherokees. He said he lowered his stall
speed by 7 mph.

I was doing 45 deg "S" turns at 45 knts indicated (at altitude)
easily. Lots of protest from the horn, but solid, no buffeting....

We have it at 4 knot difference so far, maybe 5..

One of my partners frequents a 1600 ft strip near his parents home. We
thought the extra margin would be a good investment.

More testing to come.. Will post results here if anyone interested.

Cheers!

Dave ...


On Wed, 03 Jan 2007 15:25:04 GMT, Larry Dighera
wrote:

On Wed, 03 Jan 2007 14:24:15 GMT, "Steve Foley"
wrote in j0Pmh.2$5g.0@trndny01:

I think he's referring to Art Mattson's high performance take-off procedure
for Cherokees.

See http://www.pipermods.com/

Dave must have some information additional to that provided on the web
site, as is see no mention of moving the elevator to the stop at
rotation:


http://www.pipermods.com/shortfield.htm
Short Field Takeoff Procedure
Getting the best short field performance out of your Cherokee begins
before reaching the end of the runway. This requires leaning to
slightly rich of max. power at your runup. This is achieved by leaning
to maximum static RPM and then richening the mixture slightly as you
would at your cruise altitude. (If you plan to cruise more than 2000
AGL, you will need to further richen the mixture.)

Never stop on the end of the runway. After you are cleared for
takeoff, make a rolling turn onto the runway-no flaps. When you reach
an angle of 45 deg. to the runway, start accelerating so that by the
time you have completed your turn, you are at full throttle.
Accelerate to your predetermined rotation speed (this is between 45
and 60 mph depending on mods, temperature and loading), at this speed,
pull in 2 notches of flaps, count 1.... 2 and rotate! You can take
your first notch of flaps off fairly soon after gaining some speed and
take the second one out as you continue to gain speed.

This procedure is like adding 300ft+ to the runway which reduces your
"pucker factor" for clearing obstacles. Practice on a longer than
needed runway and get comfortable with it before doing it on a short
field. I use this procedure on all takeoffs regardless of runway
length, as I go into short grass strips regularly and want the
procedure to be second nature. By using ths [sic] procedure, you will
quickly discover that your Cherokee is capable of more than you
realized.

For a first-hand account of how well this works, read Jim Cavanaugh's
article from Pipers Magazine.

Now you caught my interest.

What were the first two mods again? VGs and gap seals?

KC

PA28-180 Cherokee Challenger

On Wed, 03 Jan 2007 20:35:48 -0400, Dave
wrote in
:


Was not quoting Art here, although he mentioned to me verbally that he
has used full back yoke to rotate, especially with the heavier
engined cherokees and the "full fuel, 2 heavy front seat Pilot/pax
and no baggage" situation....

So the forward CG required more aggressive elevator.

I had it well back, but have not hit the stop yet, and may never.

Apparently, if done to soon, the aircraft simply won't lift...

The aggressive application of elevator reduces airspeed below stall
speed I suppose.

Although having spoken to several about this mod, I was only
slightly prepared for the result..

Now, remember, it was cold, slight head wind, and I was light.

Brakes held , full RPM, and let go....

I was well in the air at the 500 ft marker..

That's impressive. The information here
http://www.planeandpilotmag.com/content/specs/2006/piper_cherokee140.html
indicates that 800' is the book value. That works out to about a 38%
performance increase.

The deck angle was ...umm... "interesting" .

You mean you should have been wearing a parachute to comply with
91.307(c)(2)? :-)

And the little Warrior just wanted to keep going up... no wobbles, no
stall warning, no buffeting, just the most rapid "up" I have ever
experienced with 150 horses...

Gap seals help too.

Over a year ago. I got an E-mail from a straight wing Cherokee pilot
who indicated that these two mods are " the FIRST ones to spend money
on " when it comes to the Cherokees. He said he lowered his stall
speed by 7 mph.

I was doing 45 deg "S" turns at 45 knts indicated (at altitude)
easily. Lots of protest from the horn, but solid, no buffeting....

Cherokees were designed with a laminar flow airfoil, but the rivets
and any chipped paint, bugs and irregularities tend to cause premature
airflow separation. Apparently the VGs overcome that to some extent.

We have it at 4 knot difference so far, maybe 5..

One of my partners frequents a 1600 ft strip near his parents home. We
thought the extra margin would be a good investment.

More testing to come.. Will post results here if anyone interested.

I'm interested. I'm planning on grading a runway on an 80 acre parcel
if my offer is accepted. This parcel only permits about a 1,500'
length with some tall oaks in a ravine at one end, so anything that
reduces takeoff ground run is going to be installed. I'm hoping to
find a nice PA28-236, so keep us posted.