questions re speed mods for cherokees

[Bob Noel]

In a fit of insanity, I'm considering adding some speed mods to my
160hp cherokee 140.

For those that have Knots-2-U, LoPresti, or Laminarflow speed mods,
such as wing root seals, aileron seals, stabilator seals, flap hinge
fairings, I have some questions.

1) How have they stood up over time?

2) Were the installation times reasonable or hopelessly optimistic?

3) Did you feel any mods weren't particularly useful?

4) Do they make preflights and/or annual inspections more difficult?

Thanks

--
Bob Noel
no one likes an educated mule

[Paul kgyy]

If you believe the advertising, you can add 20 knots (up to 10 mods at
about 2 knots each). In practice, however, you should not plan on any
speed increase, IMO. Many of the mods do improve slow speed handling
and stall behaviour, but that's already pretty benign in the Cherokee.

I've seen reports of 10 knots' gain but I don't personally believe it.
TAS is not an easy thing to measure with any accuracy. All atmospheric
conditions must be identical to compare, and they never are.

I understand the desire to reward a loved airframe with money, but
personally believe a good panel GPS or STEC autopilot provides more
enjoyment for the $$$.

[Bob Noel]

In article . com>,
"Paul kgyy" > wrote:

> If you believe the advertising, you can add 20 knots (up to 10 mods at
> about 2 knots each). In practice, however, you should not plan on any
> speed increase, IMO. Many of the mods do improve slow speed handling
> and stall behaviour, but that's already pretty benign in the Cherokee.
>
> I've seen reports of 10 knots' gain but I don't personally believe it.
> TAS is not an easy thing to measure with any accuracy. All atmospheric
> conditions must be identical to compare, and they never are.

I'm not planning on a speed increase. During overhaul I had the
engine increased to 160hp and re-pitched the prop to a cruise prop
(60 inch pitch - standard for the 160hp cherokees).


> I understand the desire to reward a loved airframe with money, but
> personally believe a good panel GPS or STEC autopilot provides more
> enjoyment for the $$$.

I already have an STEC 40, and a good VFR LORAN. GPS wouldn't
provide any increased utility.

--
Bob Noel
no one likes an educated mule

[Jay Masino]

Bob Noel > wrote:
> In a fit of insanity, I'm considering adding some speed mods to my
> 160hp cherokee 140.

It's not insane. I have the Knots2U kit, and the AMR&D mods.

> For those that have Knots-2-U, LoPresti, or Laminarflow speed mods,
> such as wing root seals, aileron seals, stabilator seals, flap hinge
> fairings, I have some questions.
> 1) How have they stood up over time?

I've had some problems keeping paint on my AMR&D vortex gens (bad batch
of zinc chromate). Also, the gap seals on the Knots2U kit use teflon tape
to protect the aluminum where things rub. As the tape gets old and
deteriorates, you'll get some scratching of the paint where the seals
touch the underside of the control surfaces. It's not that big a deal.
I keep meaning to replace that tape.

> 2) Were the installation times reasonable or hopelessly optimistic?

I did most of it myself under A&P/IA supervision. It wasn't a big deal.

> 3) Did you feel any mods weren't particularly useful?

I suspect that AMR&D "prop tip mod" probably didn't do very much. The
gap seals worked well.

> 4) Do they make preflights and/or annual inspections more difficult?

My mechanic grumbles all the time about it making it difficult for him to
inspect the aileron control rods, but in reality, it's not that big a
deal. There's a little section of the gap seal that unscrews and comes
off in the vicinity of the control rods.

--- Jay



--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

[[email protected]]

Bob Noel > wrote:
: 3) Did you feel any mods weren't particularly useful?

I can only speak for the mods I've witnessed personally on my plane and other
cherokee drivers I know around here. From what I've seen, the single-best one to do
for a PA-28 is the Mattson VG mod. It's only four little tabs on each wing root.
Stock the plane waffles on a stall at 60 mph IAS with full flaps and power. With
them, you can hang it on the prop at 45 mph IAS. It reduced the sink rate (and so
also increased climb a bit... 100-200 fpm, maybe). It doesn't give you speed, but it
doesn't hurt either (although it looks like it would).

Other than that, I'm skeptical of much of them. They all probably do a little
bit, but certainly nothing magical. I think the VGs require aftermarket wingtips,
too... another good thing to do.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Nathan Young]

On Thu, 04 Aug 2005 08:51:52 -0400, Bob Noel
> wrote:

>
>In a fit of insanity, I'm considering adding some speed mods to my
>160hp cherokee 140.
>
>For those that have Knots-2-U, LoPresti, or Laminarflow speed mods,
>such as wing root seals, aileron seals, stabilator seals, flap hinge
>fairings, I have some questions.
>
>1) How have they stood up over time?
>
>2) Were the installation times reasonable or hopelessly optimistic?
>
>3) Did you feel any mods weren't particularly useful?
>
>4) Do they make preflights and/or annual inspections more difficult?

I have the full K2U suite on my PA28-180. I am happy with them - at
least 5mph cleanup, probably closer to 8 when flying at higher
altitudes (don't know what that makes a difference).

#1. Well.
#2. I had K2U do the install, and I think they billed my 20 or 30
hrs.
#3. I did the mods pretty much at the same time (except wingtips -
they were backordered) so I can't discern much individual difference.
I do notice a speed difference and float in the flare difference with
the wheelpant covers - so they are probably a big chunk of the
improvement. Aileron seals are great for roll authority as is the
stabilator seal for pitch authority.

The best add-in was the wingtips with landing lights.

#4. Only pain is removing/installing the wheel pant covers. It is a
dirty (brake/tire dust) job and requires about 15-20 screws on each
wheelpant. My mechanic complains, so I do it for him prior to the
annual and any other brake maintenance.

[Nathan Young]

On Thu, 04 Aug 2005 08:51:52 -0400, Bob Noel
> wrote:

>
>In a fit of insanity, I'm considering adding some speed mods to my
>160hp cherokee 140.
>
>For those that have Knots-2-U, LoPresti, or Laminarflow speed mods,
>such as wing root seals, aileron seals, stabilator seals, flap hinge
>fairings, I have some questions.
>
>1) How have they stood up over time?
>
>2) Were the installation times reasonable or hopelessly optimistic?
>
>3) Did you feel any mods weren't particularly useful?
>
>4) Do they make preflights and/or annual inspections more difficult?
>
>Thanks

You should also consider the powerflowsystems exhaust. It sounds like
a winner.

[[email protected]]

Nathan Young > wrote:
: You should also consider the powerflowsystems exhaust. It sounds like
: a winner.

I don't know that I'd say that. It definately sounds "different," but winner
doesn't come to mind. More like a rapid-farting airplane.... :)

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************