The Murphy Builders Site

I bought these for another airplane, but thought I would try them first
temporarily on my amphib Rebel to see what difference they made. After
attaching them with double sided carpet tape at the prescribed location on
the wing, I took it up for some stall trials. My gross weight was exactly
at
1650 for the test. I tried it first at the neutral flaperon setting. I
hadn't done a stall for a while, but seemed to recall it stalling between
45
and 50 mph at that weight with neutral flaperons. Well, I kept pulling
back
and watching my airspeed go all the way down to below 40 (around about 38,
I
think, as it doesn't read too accurately below that) before it finally
felt
like a stall at a ridiculously high nose angle. So there was definitely a
dramatic drop in stall speed. Because it was so slow already, I didn't
even
try it with full flaps.



However, it was harder to tell what difference if any it made to my
take-offs. When you are flying floats, you can't rotate at a high angle of
attack because of the float tails. My take-offs were plenty fast, but
never
had a chance to put it to the test in a high elevation lake on a hot day
or
with a real heavy load. At near sea level my take-offs were always pretty
fast anyway unless I was really loaded down. I flew this way for a couple
of
weeks, and it seemed to perform pretty well, but I had no quantitative way
to measure my take-offs or climb rates (which also seemed better).



I did not notice any other handling differences or change in cruise speed.
They are also supposed to improve low speed handling, but with floats and
my
previous 50 mph stall speed, I usually would never fly below about 70
anyway.



So for this long weekend, I removed the VGs to see if I would notice a
difference again. Of course the first thing I tried was the stall speed
once
I had the right fuel quantity to make it 1650 gross again. This time it
buffeted at around 50 with a clear fast dropping stall by 48 mph. That
means
the VGs probably improved stall by about 10 to 12 mph which is a lot more
than I expected. And that was at neutral flaps.



I did a few take-offs on land and water, and sure enough it seemed to be a
little longer to take-off without the VGs. It was especially noticeable on
the water, where I needed to be a little more patient so I didn't ruin my
sweet spot trying to lift it off early. Also, my climb rate also seemed
lower by about 2 or 300 fpm.



The only problem with this testing, is that it is a little too qualitative
(other than the stalls), so am not prepared to say with certainty, that
the
VGs did indeed improve take-offs and climbs. The real test would be at
higher altitudes with a good load and I just haven't had a chance to try
that yet. Also, taking off beside another Rebel would help.



However, next week I will be flying with Bruce G, so am going to put them
on
again, and see if we can get a better sense of comparison with his plane.



Anyway, thought this would be of interest to the group, as I'm not sure if
there is anyone else out there flying a Rebel with the VGs.



If these things actually make a difference at high elevation lakes, then
maybe I won't need that 0360 clone after all.



Related to this, was talking to another Rebel float plane pilot, (won't
mention his name to protect the innocent) but he told me it took him half
an
hour this morning trying to get off a 3800 foot lake. He was pretty loaded
with camping gear, full fuel and his wife, so I was not surprised, even
though he had the 160 hp 0320 (mine is only 150 hp). He said his biggest
problem was getting on the step, and he finally did it after he got a
little
headwind breeze. He said he tried every trick in the book, with wakes,
rocking it, flaps, no flaps, but it just wouldn't go. Once on the step, he
eventually was able to raise one float, allowing it to gain more speed
until
he finally lifted off. He had to keep flaps in neutral initially, and then
full flap at speed to lift off.



So that would have been a good test for the VGs.



Walter





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I bought these for another airplane, but thought I would try them first
temporarily on my amphib Rebel to see what difference they made. After
attaching them with double sided carpet tape at the prescribed location on
the wing, I took it up for some stall trials. My gross weight was exactly
at
1650 for the test. I tried it first at the neutral flaperon setting. I
hadn't done a stall for a while, but seemed to recall it stalling between
45
and 50 mph at that weight with neutral flaperons. Well, I kept pulling
back
and watching my airspeed go all the way down to below 40 (around about 38,

I
think, as it doesn't read too accurately below that) before it finally
felt
like a stall at a ridiculously high nose angle. So there was definitely a
dramatic drop in stall speed. Because it was so slow already, I didn't
even
try it with full flaps.



However, it was harder to tell what difference if any it made to my
take-offs. When you are flying floats, you can't rotate at a high angle of
attack because of the float tails. My take-offs were plenty fast, but
never
had a chance to put it to the test in a high elevation lake on a hot day
or
with a real heavy load. At near sea level my take-offs were always pretty
fast anyway unless I was really loaded down. I flew this way for a couple
of
weeks, and it seemed to perform pretty well, but I had no quantitative way
to measure my take-offs or climb rates (which also seemed better).



I did not notice any other handling differences or change in cruise speed.
They are also supposed to improve low speed handling, but with floats and
my
previous 50 mph stall speed, I usually would never fly below about 70
anyway.



So for this long weekend, I removed the VGs to see if I would notice a
difference again. Of course the first thing I tried was the stall speed
once
I had the right fuel quantity to make it 1650 gross again. This time it
buffeted at around 50 with a clear fast dropping stall by 48 mph. That
means
the VGs probably improved stall by about 10 to 12 mph which is a lot more
than I expected. And that was at neutral flaps.



I did a few take-offs on land and water, and sure enough it seemed to be a
little longer to take-off without the VGs. It was especially noticeable on
the water, where I needed to be a little more patient so I didn't ruin my
sweet spot trying to lift it off early. Also, my climb rate also seemed
lower by about 2 or 300 fpm.



The only problem with this testing, is that it is a little too qualitative
(other than the stalls), so am not prepared to say with certainty, that
the
VGs did indeed improve take-offs and climbs. The real test would be at
higher altitudes with a good load and I just haven't had a chance to try
that yet. Also, taking off beside another Rebel would help.



However, next week I will be flying with Bruce G, so am going to put them
on
again, and see if we can get a better sense of comparison with his plane.



Anyway, thought this would be of interest to the group, as I'm not sure if
there is anyone else out there flying a Rebel with the VGs.



If these things actually make a difference at high elevation lakes, then
maybe I won't need that 0360 clone after all.



Related to this, was talking to another Rebel float plane pilot, (won't
mention his name to protect the innocent) but he told me it took him half
an
hour this morning trying to get off a 3800 foot lake. He was pretty loaded
with camping gear, full fuel and his wife, so I was not surprised, even
though he had the 160 hp 0320 (mine is only 150 hp). He said his biggest
problem was getting on the step, and he finally did it after he got a
little
headwind breeze. He said he tried every trick in the book, with wakes,
rocking it, flaps, no flaps, but it just wouldn't go. Once on the step, he
eventually was able to raise one float, allowing it to gain more speed
until
he finally lifted off. He had to keep flaps in neutral initially, and then
full flap at speed to lift off.



So that would have been a good test for the VGs.



Walter





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These are the ones I tried. Cheap, only $95 US.
http://landshorter.com/

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Bill
Maxwell
Sent: July 3, 2006 8:19 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] VGs

Very interesting Walter. Which particular VGs did you use?
Thanks

Bill, 753R
----- Original Message -----
From: "Walter Klatt" <Walter.Klatt@shaw.ca>
To: "Rebel-Builders" <rebel-builders@dcsol.com>
Sent: Tuesday, July 04, 2006 12:39 PM
Subject: [rebel-builders] VGs

I bought these for another airplane, but thought I would try them first
temporarily on my amphib Rebel to see what difference they made. After
attaching them with double sided carpet tape at the prescribed location
on
the wing, I took it up for some stall trials. My gross weight was exactly
at
1650 for the test. I tried it first at the neutral flaperon setting. I
hadn't done a stall for a while, but seemed to recall it stalling between
45
and 50 mph at that weight with neutral flaperons. Well, I kept pulling
back
and watching my airspeed go all the way down to below 40 (around about
38,

I
think, as it doesn't read too accurately below that) before it finally
felt
like a stall at a ridiculously high nose angle. So there was definitely a
dramatic drop in stall speed. Because it was so slow already, I didn't
even
try it with full flaps.



However, it was harder to tell what difference if any it made to my
take-offs. When you are flying floats, you can't rotate at a high angle
of
attack because of the float tails. My take-offs were plenty fast, but
never
had a chance to put it to the test in a high elevation lake on a hot day
or
with a real heavy load. At near sea level my take-offs were always pretty
fast anyway unless I was really loaded down. I flew this way for a couple
of
weeks, and it seemed to perform pretty well, but I had no quantitative
way
to measure my take-offs or climb rates (which also seemed better).



I did not notice any other handling differences or change in cruise
speed.
They are also supposed to improve low speed handling, but with floats and
my
previous 50 mph stall speed, I usually would never fly below about 70
anyway.



So for this long weekend, I removed the VGs to see if I would notice a
difference again. Of course the first thing I tried was the stall speed
once
I had the right fuel quantity to make it 1650 gross again. This time it
buffeted at around 50 with a clear fast dropping stall by 48 mph. That
means
the VGs probably improved stall by about 10 to 12 mph which is a lot more
than I expected. And that was at neutral flaps.



I did a few take-offs on land and water, and sure enough it seemed to be
a
little longer to take-off without the VGs. It was especially noticeable
on
the water, where I needed to be a little more patient so I didn't ruin my
sweet spot trying to lift it off early. Also, my climb rate also seemed
lower by about 2 or 300 fpm.



The only problem with this testing, is that it is a little too
qualitative
(other than the stalls), so am not prepared to say with certainty, that
the
VGs did indeed improve take-offs and climbs. The real test would be at
higher altitudes with a good load and I just haven't had a chance to try
that yet. Also, taking off beside another Rebel would help.



However, next week I will be flying with Bruce G, so am going to put them
on
again, and see if we can get a better sense of comparison with his plane.



Anyway, thought this would be of interest to the group, as I'm not sure
if
there is anyone else out there flying a Rebel with the VGs.



If these things actually make a difference at high elevation lakes, then
maybe I won't need that 0360 clone after all.



Related to this, was talking to another Rebel float plane pilot, (won't
mention his name to protect the innocent) but he told me it took him half
an
hour this morning trying to get off a 3800 foot lake. He was pretty
loaded
with camping gear, full fuel and his wife, so I was not surprised, even
though he had the 160 hp 0320 (mine is only 150 hp). He said his biggest
problem was getting on the step, and he finally did it after he got a
little
headwind breeze. He said he tried every trick in the book, with wakes,
rocking it, flaps, no flaps, but it just wouldn't go. Once on the step,
he
eventually was able to raise one float, allowing it to gain more speed
until
he finally lifted off. He had to keep flaps in neutral initially, and
then
full flap at speed to lift off.



So that would have been a good test for the VGs.



Walter





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I bought these for another airplane, but thought I would try them first
temporarily on my amphib Rebel to see what difference they made.

Hi Walter

I guess I always assumed that there is not much wing lift prior to
getting on the step but you reminded me of a time I got airborne
before
getting on the step. It was exciting (OK scary!) but the wind was
pretty
strong that day and I was in a fairly fast moving river as well.

I don't recall that leaving the flaps up helped getting an Otter
onto
the step. That might indicate that we were indeed getting some
lift and
the flaps helped increase it and move the center of lift aft. We
also
always thought that the flaps help deflect the propblast downwards
and
that it then tended to bounce back off the water and help lift the
tail.
I have no idea what works best on a Rebel of course.

Ken

WALTER KLATT wrote:

Ken, I was thinking too, that the real difference is not 12 mph,

because at extreme angles of attack, which is what the VGs give
you, the airspeed indicator is also far from direct to the
airflow. But that is what my IAS was showing. I might mention
also, that on my airplane, my pitot is pointed more down than most
(a refueling contact incident), so that it probably reads higher
than most Rebels during the stall. I am not sure if checking IAS
against my GPS is useful at those low speeds if comparing with VGs
against no VGs, due to the differences in angles of attack. An
absolute comparison of groundspeed, however, should do it, but not
sure how good I can fly 3 headings at stall speeds to get a proper
average.>

As for getting on the step, that is indeed where I think the VGs

might help. That is because they provide more lift at a higher
angle of attack which is what you have when trying to get on the
step. So if the wings can lift more instead of just the floats
pushing/plowing water, then they should help. The elevator seems
to have good authority on the water even at low speeds, so not
sure if that would help, but might be worth a try as well.

With my airplane, I have never had trouble getting on the step,

From: Walter Klatt <Walter.Klatt@shaw.ca>
Sent: Jul 3, 2006 10:39 PM
To: Rebel-Builders <rebel-builders@dcsol.com>
Subject: [rebel-builders] VGs

I bought these for another airplane, but thought I would try them first
temporarily on my amphib Rebel to see what difference they made. After
attaching them with double sided carpet tape at the prescribed location on
the wing, I took it up for some stall trials. My gross weight was exactly at
1650 for the test. I tried it first at the neutral flaperon setting. I
hadn't done a stall for a while, but seemed to recall it stalling between 45
and 50 mph at that weight with neutral flaperons. Well, I kept pulling back
and watching my airspeed go all the way down to below 40 (around about 38, I
think, as it doesn't read too accurately below that) before it finally felt
like a stall at a ridiculously high nose angle. So there was definitely a
dramatic drop in stall speed. Because it was so slow already, I didn't even
try it with full flaps.



However, it was harder to tell what difference if any it made to my
take-offs. When you are flying floats, you can't rotate at a high angle of
attack because of the float tails. My take-offs were plenty fast, but never
had a chance to put it to the test in a high elevation lake on a hot day or
with a real heavy load. At near sea level my take-offs were always pretty
fast anyway unless I was really loaded down. I flew this way for a couple of
weeks, and it seemed to perform pretty well, but I had no quantitative way
to measure my take-offs or climb rates (which also seemed better).



I did not notice any other handling differences or change in cruise speed.
They are also supposed to improve low speed handling, but with floats and my
previous 50 mph stall speed, I usually would never fly below about 70
anyway.



So for this long weekend, I removed the VGs to see if I would notice a
difference again. Of course the first thing I tried was the stall speed once
I had the right fuel quantity to make it 1650 gross again. This time it
buffeted at around 50 with a clear fast dropping stall by 48 mph. That means
the VGs probably improved stall by about 10 to 12 mph which is a lot more
than I expected. And that was at neutral flaps.



I did a few take-offs on land and water, and sure enough it seemed to be a
little longer to take-off without the VGs. It was especially noticeable on
the water, where I needed to be a little more patient so I didn't ruin my
sweet spot trying to lift it off early. Also, my climb rate also seemed
lower by about 2 or 300 fpm.



The only problem with this testing, is that it is a little too qualitative
(other than the stalls), so am not prepared to say with certainty, that the
VGs did indeed improve take-offs and climbs. The real test would be at
higher altitudes with a good load and I just haven't had a chance to try
that yet. Also, taking off beside another Rebel would help.



However, next week I will be flying with Bruce G, so am going to put them on
again, and see if we can get a better sense of comparison with his plane.



Anyway, thought this would be of interest to the group, as I'm not sure if
there is anyone else out there flying a Rebel with the VGs.



If these things actually make a difference at high elevation lakes, then
maybe I won't need that 0360 clone after all.



Related to this, was talking to another Rebel float plane pilot, (won't
mention his name to protect the innocent) but he told me it took him half an
hour this morning trying to get off a 3800 foot lake. He was pretty loaded
with camping gear, full fuel and his wife, so I was not surprised, even
though he had the 160 hp 0320 (mine is only 150 hp). He said his biggest
problem was getting on the step, and he finally did it after he got a little
headwind breeze. He said he tried every trick in the book, with wakes,
rocking it, flaps, no flaps, but it just wouldn't go. Once on the step, he
eventually was able to raise one float, allowing it to gain more speed until
he finally lifted off. He had to keep flaps in neutral initially, and then
full flap at speed to lift off.



So that would have been a good test for the VGs.



Walter





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From: Walter Klatt <Walter.Klatt@shaw.ca>
Sent: Jul 3, 2006 10:39 PM
To: Rebel-Builders <rebel-builders@dcsol.com>
Subject: [rebel-builders] VGs

I bought these for another airplane, but thought I would try them first
temporarily on my amphib Rebel to see what difference they made. After
attaching them with double sided carpet tape at the prescribed location on
the wing, I took it up for some stall trials. My gross weight was exactly

1650 for the test. I tried it first at the neutral flaperon setting. I
hadn't done a stall for a while, but seemed to recall it stalling between

and 50 mph at that weight with neutral flaperons. Well, I kept pulling back
and watching my airspeed go all the way down to below 40 (around about 38,

think, as it doesn't read too accurately below that) before it finally felt
like a stall at a ridiculously high nose angle. So there was definitely a
dramatic drop in stall speed. Because it was so slow already, I didn't even
try it with full flaps.



However, it was harder to tell what difference if any it made to my
take-offs. When you are flying floats, you can't rotate at a high angle of
attack because of the float tails. My take-offs were plenty fast, but never
had a chance to put it to the test in a high elevation lake on a hot day or
with a real heavy load. At near sea level my take-offs were always pretty
fast anyway unless I was really loaded down. I flew this way for a couple

weeks, and it seemed to perform pretty well, but I had no quantitative way
to measure my take-offs or climb rates (which also seemed better).



I did not notice any other handling differences or change in cruise speed.
They are also supposed to improve low speed handling, but with floats and

previous 50 mph stall speed, I usually would never fly below about 70
anyway.



So for this long weekend, I removed the VGs to see if I would notice a
difference again. Of course the first thing I tried was the stall speed

I had the right fuel quantity to make it 1650 gross again. This time it
buffeted at around 50 with a clear fast dropping stall by 48 mph. That

the VGs probably improved stall by about 10 to 12 mph which is a lot more
than I expected. And that was at neutral flaps.



I did a few take-offs on land and water, and sure enough it seemed to be a
little longer to take-off without the VGs. It was especially noticeable on
the water, where I needed to be a little more patient so I didn't ruin my
sweet spot trying to lift it off early. Also, my climb rate also seemed
lower by about 2 or 300 fpm.



The only problem with this testing, is that it is a little too qualitative
(other than the stalls), so am not prepared to say with certainty, that the
VGs did indeed improve take-offs and climbs. The real test would be at
higher altitudes with a good load and I just haven't had a chance to try
that yet. Also, taking off beside another Rebel would help.



However, next week I will be flying with Bruce G, so am going to put them

again, and see if we can get a better sense of comparison with his plane.



Anyway, thought this would be of interest to the group, as I'm not sure if
there is anyone else out there flying a Rebel with the VGs.



If these things actually make a difference at high elevation lakes, then
maybe I won't need that 0360 clone after all.



Related to this, was talking to another Rebel float plane pilot, (won't
mention his name to protect the innocent) but he told me it took him half

hour this morning trying to get off a 3800 foot lake. He was pretty loaded
with camping gear, full fuel and his wife, so I was not surprised, even
though he had the 160 hp 0320 (mine is only 150 hp). He said his biggest
problem was getting on the step, and he finally did it after he got a

headwind breeze. He said he tried every trick in the book, with wakes,
rocking it, flaps, no flaps, but it just wouldn't go. Once on the step, he
eventually was able to raise one float, allowing it to gain more speed

he finally lifted off. He had to keep flaps in neutral initially, and then
full flap at speed to lift off.



So that would have been a good test for the VGs.



Walter





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Hi everyone,
I thought I'd add my experiences on vgs. I've had them on since the
90s and I love them. I was the first Rebel to use Micro Aerodynamics
and did some experimenting. The normal rule of thumb is to install
the leading edge of the vg at 10% of the cord, which for us is 6
inches. This is a compromise for a stall speed reduction and minimal
impact on cruise. I chose to put them at 2.5 inches back as I wanted
to really lower my stall and was willing to take a hit on cruise
speed. Moving forward of 10% into the high pressure point of the
leading edge creates a lot of drag. However, my Rebel doesn't stall,
it starts a controlled mush at about 37-38 mph at 3500 feet. This
location keeps the airflow attached to the wing, but a side effect is
a very high angle of attack for landing. I would touch down tail
wheel first, then as the AOA lowered, it would drop on the mains. So
I installed 29 inch Alaska Bushwheels and that problem was solved. I
went to split flaps before Murphy offered a retrofit kit, and tried 6
inches back from the wing root to the end of the flaps and 2.5 inches
from mid wing to the tips, but the stall wasn't as low as the full
wing at 2.5 inches. So, with all the drag of vgs and tires, my cruise
is about 85mph. However, at both 6 and 2.5 inches, the aileron
response is much crisper, even at 40mph.
When I have time, I want to play with either a slotted or Fowler type
flap for slower speed and a low nose angle. Daryl Murphy told me the
flap brackets we have are designed for a max of 25 degrees, so a new
mounting bracket/hinge setup will be required. Big flaps are nice
cause they move the center of lift back giving you a better over the
nose view for landing and a slower speed. The only draw back may be a
lack of elevator authority cause of wing flow deflection.
One last item concerning vgs is the horizontal stab and elevator. In
the past, I've had a few instances of being light for landing
(forward cg) and come in at an idle and rounded out for the flare,
but the tail wouldn't respond. What was happening was the elevator
was stalling as I pulled back on the stick (high elevator deflection
and no prop blast for airflow). I put Micro Aerodynamics vgs on the
bottom only of the stab right in front of the elevator. A huge
difference in control with no reduction in speed and absolutely no
elevator stall ever. Even if you don't want wing vgs, I highly
recommend the elevator install.
One last thing, I tried the Turbine Cubs of Wyoming slats that Wayne
Mackay designed last summer. All I can say is don't do it. They work
great for a flat bottomed airfoil like a Cub or Maule, but are an
absolute disaster with the 4415 airfoil that the Rebel uses.
Thankfully, they took the slats back for a full refund. If anyone
wants to talk about whatever, I'm at 509-995-6372, Spokane, WA
(Pacific time). Thanks




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