Murphy SeaFins

[Mike Kimball]

I emailed Murphy about the horizontal stabilizer service bulletins and Robin
emailed me with a response the next day. I didn't see the stuff on the list
that would tell me that the horizontal stabilizer service bulletin wasn't
meant for the Super Rebel before I sent my email. Despite the fact that I
clearly indicated I had a Super Rebel, Robin did not mention that the
stabilizer fix wasn't for the SR. He just said that the mod kits were no
charge. I'm guessing that he is a very busy man right now. In any case, I
asked about the sea fin parts at the same time and that probably got him off
of the "fix" idea and onto a voluntary "mod" idea for me. The parts for the
sea fins, which are little winglets on the ends of the stabilizer, are $187
USD. I noticed on MAMs website that their Moose has the seafins and a
ventral fin. I was wondering if both are really necessary. I called Chris
Gill in Anchorage about his SR on floats with only a ventral fin. He says
control authority is great with just the ventral fin. He also said that the
folks at Montana floats told him that the SR definitely needs the ventral
fin after test flights they performed. I don't know if there is something
about the Moose that warrants the extra surface area on the horizontal stab
but I'm not going to add the seafins. I'm going to stick with just the
ventral fin. But I am going to ask MAM about why they felt they needed the
seafins on the Moose. Doesn't seem like it adds much surface area.

Mike Kimball
SR044




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[Al Paxhia]

Hi Mike,
The following comments are for float equipped airplanes only, and do not
apply to others.
I have both the ventral fin and the seafins. I feel the ventral fin is a
must. The seafins also help a great deal. I flew from Seattle to Florida and
back without the seafins, in warm climate areas there is no relaxing, lots
of adverse yaw. With seafins it is a stable airplane anytime. Turns do
require lots of rudder, but what did my instructor always yell, " use those
rudders, keep the ball centered!".
The seafins can be added later, fly and decide, but if you can install
nutplates in the end ribs now it's a 10 minute installation later.
Al
Moose, N526AP
----- Original Message -----
From: "Mike Kimball" <mkimball@gci.net>
To: "Rebel List" <rebel-builders@dcsol.com>
Sent: Friday, November 26, 2004 12:44 PM
Subject: Murphy SeaFins

I emailed Murphy about the horizontal stabilizer service bulletins and
Robin
emailed me with a response the next day. I didn't see the stuff on the
list
that would tell me that the horizontal stabilizer service bulletin wasn't
meant for the Super Rebel before I sent my email. Despite the fact that I
clearly indicated I had a Super Rebel, Robin did not mention that the
stabilizer fix wasn't for the SR. He just said that the mod kits were no
charge. I'm guessing that he is a very busy man right now. In any case,
I
asked about the sea fin parts at the same time and that probably got him
off
of the "fix" idea and onto a voluntary "mod" idea for me. The parts for
the
sea fins, which are little winglets on the ends of the stabilizer, are
$187
USD. I noticed on MAMs website that their Moose has the seafins and a
ventral fin. I was wondering if both are really necessary. I called
Chris
Gill in Anchorage about his SR on floats with only a ventral fin. He says
control authority is great with just the ventral fin. He also said that
the
folks at Montana floats told him that the SR definitely needs the ventral
fin after test flights they performed. I don't know if there is something
about the Moose that warrants the extra surface area on the horizontal
stab
but I'm not going to add the seafins. I'm going to stick with just the
ventral fin. But I am going to ask MAM about why they felt they needed
the
seafins on the Moose. Doesn't seem like it adds much surface area.

Mike Kimball
SR044




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[mike.davis]

One thing I think worth pointing out here is that both Chris Gill and Mike
Kimball used the old aluminum piece in front of the vertical fin instead of
the fiberglass fairing. So they have the 185 style tail which probably adds
as much additional area as the ventral fin does. This may be why Chris Gill
doesn't feel he needs the sea fins.

Mike

-> Hi Mike,
-> The following comments are for float equipped airplanes only, and do not
-> apply to others.
-> I have both the ventral fin and the seafins. I feel the ventral fin is a
-> must. The seafins also help a great deal. I flew from Seattle to Florida
and
-> back without the seafins, in warm climate areas there is no relaxing, lots
-> of adverse yaw. With seafins it is a stable airplane anytime. Turns do
-> require lots of rudder, but what did my instructor always yell, " use
those
-> rudders, keep the ball centered!".
-> The seafins can be added later, fly and decide, but if you can install
-> nutplates in the end ribs now it's a 10 minute installation later.
-> Al




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[Ryan Mowat]

I concure with Al. Sea fins provide more stability with no cross wind
landing loss as the side area (profile) is the same with or without them. I
have flown with sea fins and no ventral fin and visa versa and my experience
is that both is best. I have 2.5 sqft more dorsal fin then Al and the
ventral fin is still necessary as are the sea fins for safe fligth.
Especially turning cross wind off a small strip - big danger in dropping the
inside wing and stalling without the additional stability. I read about
this in "how to fly float books" but until it happened to me in real life I
did not realize just how important this is.

Ryan

On Fri, 26 Nov 2004 17:13:15 -0900, mike.davis wrote

One thing I think worth pointing out here is that both Chris Gill
and Mike Kimball used the old aluminum piece in front of the
vertical fin instead of the fiberglass fairing. So they have the
185 style tail which probably adds as much additional area as the
ventral fin does. This may be why Chris Gill doesn't feel he needs
the sea fins.

Mike

-> Hi Mike,
-> The following comments are for float equipped airplanes only, and
do not -> apply to others. -> I have both the ventral fin and the
seafins. I feel the ventral fin is a -> must. The seafins also help
a great deal. I flew from Seattle to Florida and -> back without the
seafins, in warm climate areas there is no relaxing, lots -> of
adverse yaw. With seafins it is a stable airplane anytime. Turns do
-> require lots of rudder, but what did my instructor always yell, "
use those -> rudders, keep the ball centered!". -> The seafins can
be added later, fly and decide, but if you can install -> nutplates
in the end ribs now it's a 10 minute installation later. -> Al

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