Today's Message Index:
----------------------
1. 05:31 AM - Re: Losing rpm on takeoff (Noel Loveys)
2. 06:22 AM - Re: drilling/tapping fiberglass tank (carlisle)
3. 09:26 AM - Re: Re: drilling/tapping fiberglass tank (Guy Buchanan)
4. 11:43 AM - Re: Losing rpm on takeoff (mikeperkins)
5. 12:10 PM - Re: Re: Losing rpm on takeoff (Lowell Fitt)
6. 01:55 PM - Re: Re: Losing rpm on takeoff (b d)
7. 02:54 PM - Re: Re: Losing rpm on takeoff (Dave G)
8. 02:57 PM - Re: Re: Losing rpm on takeoff (Dave G)
9. 03:01 PM - Re: Losing rpm on takeoff (mikeperkins)
10. 03:43 PM - Re: Re: Losing rpm on takeoff (b d)
11. 03:50 PM - Re: Re: Losing rpm on takeoff (b d)
12. 04:05 PM - drilling/tapping fiberglass tank (rez)
13. 05:34 PM - Re: Re: Losing rpm on takeoff (b d)
14. 10:47 PM - Re: Re: Losing rpm on takeoff (Guy Buchanan)
15. 10:54 PM - Re: drilling/tapping fiberglass tank (Guy Buchanan)
16. 11:19 PM - Re: Re: Losing rpm on takeoff (b d)
17. 11:51 PM - Re: drilling/tapping fiberglass tank (Michael Gibbs)
18. 11:51 PM - Re: Re: Losing rpm on takeoff (Michael Gibbs)
Message 1
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| Subject: | Losing rpm on takeoff |
Lynn:
The only reason I can see to use the westach is it comes with the kit. (?)
I found the tinytach worked really well on the 582. When I get the 9122
going it's anyone's guess.
Noel
-----Original Message-----
From: owner-kitfox-list-server@matronics.com
[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lynn Matteson
Sent: November 30, 2010 11:58 PM
Subject: Re: Kitfox-List: Losing rpm on takeoff
Noel-
I often wonder why anybody would use a Westach....I haven't heard of
much in the way of reliability from any of their products.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Sensenich 62"x46" Wood (summer)
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying...1070 hrs (since 3-27-2006)
On Nov 30, 2010, at 9:31 PM, Noel Loveys wrote:
> I'd doubt the tach too. My plane was doing almost the same thing
> as yours and one day I had an ivo set for a go around and after an
> hour on the ground firewalled the throttle for a takeoff. Imagine
> my surprise when the plane leapt into the air and the tach
> spiralled up to the wrong side of seven grand, make that the low
> side of 8 grand! I got a Tiny Tach and quickly found my Westach
> read a consistent 20% too high.
>
>
> I often wonder how I was ever able to get the plane into the air
> with a true take off rpm of around 5400 rpm.
>
>
> Noel
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| Subject: | Re: drilling/tapping fiberglass tank |
Thanks Lynn...Sounds like my fiberglass boat repair, which contains a sheet of
fiberglass cloth and some epoxy resin might do the trick.
Chris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322048#322048
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| Subject: | Re: drilling/tapping fiberglass tank |
On 12/1/2010 8:46 PM, Lynn Matteson wrote:
> I roughed up the surface with coarse sandpaper, then added about
> 1/4"-3/8" thickness of fiberglass, using fiberglass mat and
> resin/hardener.
I did the same thing with 1/4" G-10, which is pre-made fiberglass plate
available from most plastics houses, locally or on-line. Make sure you
rough everything well and epoxy it in place. Use at least 1 1/4"
diameter pad.
Guy Buchanan
Kitfox IV-1200 / 582-C / Warp 3cs / 500 hours
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| Subject: | Re: Losing rpm on takeoff |
I have never heard a discussion involving aircraft props that mentions cavitation,
stirring air, humidity, or higher RPM during a static run-up. If you have
some references, please let me know.
A prop during a static run-up experiences a higher angle-of-attack than a prop
moving forward through air. The higher AOA produces more drag, thus more load
on the engine, and thus a lower RPM for a given power setting, not higher RPM.
Some very high-performance aircraft with fixed-pitch props (long time ago) produced
so little prop thrust (blade lift) during a static run-up that they had to
be pushed to get them rolling - the prop was stalled. Once rolling, the AOA
would gradually decrease and thrust (lift) would increase because the prop was
un-stalling.
A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a static run-up (temp
dependent), and max RPM of 6600 while climbing at Vx.
I would not be looking at the prop pitch for this particular problem.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322085#322085
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| Subject: | Re: Losing rpm on takeoff |
Mike,
I think you answered your own question. Just substitute stalled prop for
cavitating prop. I think the concept is the same In each case the prop is
pitched too high for conditions.
Lowell
--------------------------------------------------
From: "mikeperkins" <michael.perkins@rauland.com>
Sent: Thursday, December 02, 2010 11:41 AM
Subject: Kitfox-List: Re: Losing rpm on takeoff
> <michael.perkins@rauland.com>
>
> I have never heard a discussion involving aircraft props that mentions
> cavitation, stirring air, humidity, or higher RPM during a static run-up.
> If you have some references, please let me know.
>
> A prop during a static run-up experiences a higher angle-of-attack than a
> prop moving forward through air. The higher AOA produces more drag, thus
> more load on the engine, and thus a lower RPM for a given power setting,
> not higher RPM.
>
> Some very high-performance aircraft with fixed-pitch props (long time ago)
> produced so little prop thrust (blade lift) during a static run-up that
> they had to be pushed to get them rolling - the prop was stalled. Once
> rolling, the AOA would gradually decrease and thrust (lift) would increase
> because the prop was un-stalling.
>
> A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a static
> run-up (temp dependent), and max RPM of 6600 while climbing at Vx.
>
> I would not be looking at the prop pitch for this particular problem.
>
> Mike
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=322085#322085
>
>
>
Message 6
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| Subject: | Re: Losing rpm on takeoff |
Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
cavitation and with an prop in air (an airfoil), it's called a stall but
essentially the same-o same-o. We all know what is meant, we just have to
be tolerent of each others linguistics. To be technical I really don't
believe there is such a word as "un-stalling". It's either stalled or not
stalled but correct me if I'm wrong. But I do not what you mean and what
your getting at, it's like coming out of a stall condition.
Bruce
On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net> wrote:
>
> Mike,
>
> I think you answered your own question. Just substitute stalled prop for
> cavitating prop. I think the concept is the same In each case the prop is
> pitched too high for conditions.
>
> Lowell
>
> --------------------------------------------------
> From: "mikeperkins" <michael.perkins@rauland.com>
> Sent: Thursday, December 02, 2010 11:41 AM
> To: <kitfox-list@matronics.com>
> Subject: Kitfox-List: Re: Losing rpm on takeoff
>
>
>> michael.perkins@rauland.com>
>>
>> I have never heard a discussion involving aircraft props that mentions
>> cavitation, stirring air, humidity, or higher RPM during a static run-up. If
>> you have some references, please let me know.
>>
>> A prop during a static run-up experiences a higher angle-of-attack than a
>> prop moving forward through air. The higher AOA produces more drag, thus
>> more load on the engine, and thus a lower RPM for a given power setting, not
>> higher RPM.
>>
>> Some very high-performance aircraft with fixed-pitch props (long time ago)
>> produced so little prop thrust (blade lift) during a static run-up that they
>> had to be pushed to get them rolling - the prop was stalled. Once rolling,
>> the AOA would gradually decrease and thrust (lift) would increase because
>> the prop was un-stalling.
>>
>> A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a static
>> run-up (temp dependent), and max RPM of 6600 while climbing at Vx.
>>
>> I would not be looking at the prop pitch for this particular problem.
>>
>> Mike
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=322085#322085
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
Message 7
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| Subject: | Re: Losing rpm on takeoff |
I have received enough email to establish a plan of action here. Despite
the fact that reducing pitch WILL result in an overspend situation with
my particular experimental installation, I will reduce the pitch and see
what happens during high speed taxi and then climb. Many people actually
using Warp props tell me that I achieve the results I am looking for.
I understand it is counter-intuitive, but apparently it is at least
somewhat common. I have a couple of theories, but for now I'll accept
positive results and remain in doubt about the actual reason. Over a
long work life I've had to do that on many occasions, because results
are what really matters.
Thanks to Guy, Lucien and those who contributed positive and helpful
advice off list. To those who offered unhelpful advice and lectures,
thanks for the efforts. It all reminds me of a saying a friend repeats
from time to time.
"In theory, theory and practice are the same; in practice they are quite
different!" This may be one of those cases.
Dave Goddard
KF IV 1050 / 582 / Warp
----- Original Message -----
From: b d
To: kitfox-list@matronics.com
Sent: Thursday, December 02, 2010 5:52 PM
Subject: Re: Kitfox-List: Re: Losing rpm on takeoff
Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
cavitation and with an prop in air (an airfoil), it's called a stall but
essentially the same-o same-o. We all know what is meant, we just have
to be tolerent of each others linguistics. To be technical I really
don't believe there is such a word as "un-stalling". It's either stalled
or not stalled but correct me if I'm wrong. But I do not what you mean
and what your getting at, it's like coming out of a stall condition.
Bruce
On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net>
wrote:
<lcfitt@sbcglobal.net>
Mike,
I think you answered your own question. Just substitute stalled
prop for cavitating prop. I think the concept is the same In each case
the prop is pitched too high for conditions.
Lowell
--------------------------------------------------
From: "mikeperkins" <michael.perkins@rauland.com>
Sent: Thursday, December 02, 2010 11:41 AM
To: <kitfox-list@matronics.com>
Subject: Kitfox-List: Re: Losing rpm on takeoff
<michael.perkins@rauland.com>
I have never heard a discussion involving aircraft props that
mentions cavitation, stirring air, humidity, or higher RPM during a
static run-up. If you have some references, please let me know.
A prop during a static run-up experiences a higher angle-of-attack
than a prop moving forward through air. The higher AOA produces more
drag, thus more load on the engine, and thus a lower RPM for a given
power setting, not higher RPM.
Some very high-performance aircraft with fixed-pitch props (long
time ago) produced so little prop thrust (blade lift) during a static
run-up that they had to be pushed to get them rolling - the prop was
stalled. Once rolling, the AOA would gradually decrease and thrust
(lift) would increase because the prop was un-stalling.
A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a
static run-up (temp dependent), and max RPM of 6600 while climbing at
Vx.
I would not be looking at the prop pitch for this particular
problem.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322085#322085
m/" target="_blank">www.aeroelectric.com
omebuiltHELP www.homebuilthelp.com
http:/r generous support!
ronics List Features Navigator to browse
s.com/Navigator?Kitfox-List"
target="_blank">http://www.matronics.com/Navigator?Kitfox-List
ronics.com/" target="_blank">http://forums.matronics.com
=============
Message 8
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| Subject: | Re: Losing rpm on takeoff |
Yes that should be overspeed or over-rev, although either one could lead
to overspend so I guess it works.
----- Original Message -----
From: Dave G
To: rotaxengines-list@matronics.com ; kitfox-list@matronics.com
Sent: Thursday, December 02, 2010 6:51 PM
Subject: Re: Kitfox-List: Re: Losing rpm on takeoff
I have received enough email to establish a plan of action here.
Despite the fact that reducing pitch WILL result in an overspend
situation with my particular experimental installation, I will reduce
the pitch and see what happens during high speed taxi and then climb.
Many people actually using Warp props tell me that I achieve the results
I am looking for.
I understand it is counter-intuitive, but apparently it is at least
somewhat common. I have a couple of theories, but for now I'll accept
positive results and remain in doubt about the actual reason. Over a
long work life I've had to do that on many occasions, because results
are what really matters.
Thanks to Guy, Lucien and those who contributed positive and helpful
advice off list. To those who offered unhelpful advice and lectures,
thanks for the efforts. It all reminds me of a saying a friend repeats
from time to time.
"In theory, theory and practice are the same; in practice they are
quite different!" This may be one of those cases.
Dave Goddard
KF IV 1050 / 582 / Warp
----- Original Message -----
From: b d
To: kitfox-list@matronics.com
Sent: Thursday, December 02, 2010 5:52 PM
Subject: Re: Kitfox-List: Re: Losing rpm on takeoff
Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's
called cavitation and with an prop in air (an airfoil), it's called a
stall but essentially the same-o same-o. We all know what is meant, we
just have to be tolerent of each others linguistics. To be technical I
really don't believe there is such a word as "un-stalling". It's either
stalled or not stalled but correct me if I'm wrong. But I do not what
you mean and what your getting at, it's like coming out of a stall
condition.
Bruce
On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net>
wrote:
<lcfitt@sbcglobal.net>
Mike,
I think you answered your own question. Just substitute stalled
prop for cavitating prop. I think the concept is the same In each case
the prop is pitched too high for conditions.
Lowell
--------------------------------------------------
From: "mikeperkins" <michael.perkins@rauland.com>
Sent: Thursday, December 02, 2010 11:41 AM
To: <kitfox-list@matronics.com>
Subject: Kitfox-List: Re: Losing rpm on takeoff
<michael.perkins@rauland.com>
I have never heard a discussion involving aircraft props that
mentions cavitation, stirring air, humidity, or higher RPM during a
static run-up. If you have some references, please let me know.
A prop during a static run-up experiences a higher
angle-of-attack than a prop moving forward through air. The higher AOA
produces more drag, thus more load on the engine, and thus a lower RPM
for a given power setting, not higher RPM.
Some very high-performance aircraft with fixed-pitch props (long
time ago) produced so little prop thrust (blade lift) during a static
run-up that they had to be pushed to get them rolling - the prop was
stalled. Once rolling, the AOA would gradually decrease and thrust
(lift) would increase because the prop was un-stalling.
A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a
static run-up (temp dependent), and max RPM of 6600 while climbing at
Vx.
I would not be looking at the prop pitch for this particular
problem.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322085#322085
m/" target="_blank">www.aeroelectric.com
omebuiltHELP www.homebuilthelp.com
http:/r generous support!
ronics List Features Navigator to browse
s.com/Navigator?Kitfox-List"
target="_blank">http://www.matronics.com/Navigator?Kitfox-List
ronics.com/" target="_blank">http://forums.matronics.com
=============
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| Subject: | Re: Losing rpm on takeoff |
I'm not sure, but I think the drag on the prop airfoil would decrease as airspeed
went from 0 to climb. Then RPM should go up somewhat, not down, as airspeed
increased. Would that be right?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322107#322107
Message 10
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| Subject: | Re: Losing rpm on takeoff |
I don't know if you're asking me or anyone, but as speed increases, engine
RPM increases just like a car. If your climbing, your speed decreases and so
does your rpm. This is because your prop is essentially one and the same
with the air. When you are descending or diving your speed increases as well
as your rpm. Regarding sitting still on the ground (static or stationary),
the prop does lose efficiency because of stalling at higher rpms and
typically doesn't move as much air. (the prop is not one with the air as
when it's in motion) At that time the prop may stall or cavitate just as a
boat prop does in the water. We can see a hydrofoil cavitate but we can't
see an airfoil stall) This means that the air rather than be driven through
the prop as does a fan, the air begins to rotate with the prop (stalled
blades due to high angle of attack) thereby allowing the engine to run
faster but exerting less power. Once the plane begins moving, the prop then
becomes more efficient, the angle of attack from the prop to the relative
air/wind becomes less, the efficiency increases thus making the prop more
efficient thereby changing from a stalled blade to a non-stalled blade.
Does any of that make any sense? I'm trying to explain it in comparable
terms between a hydrofoil and an airfoil terminology. The thing is to
understand that when the difference between the prop and the forward
airspeed becomes less, the lesser angle of attack and the more efficient the
airfoil. Of course we have not discussed the variable angle of attack found
on a prop where the angle is great towards the prop shaft than it is towards
the tip. That's another topic for another discussion and it does play a part
in the big picture. For the discussion we are only talking about a mean
section of the prop.
I hope I didn't just confuse it even more. Sorry if I did. :-)
Bruce
On Thu, Dec 2, 2010 at 2:59 PM, mikeperkins <michael.perkins@rauland.com>wrote:
> michael.perkins@rauland.com>
>
> I'm not sure, but I think the drag on the prop airfoil would decrease as
> airspeed went from 0 to climb. Then RPM should go up somewhat, not down, as
> airspeed increased. Would that be right?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=322107#322107
>
>
Message 11
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| Subject: | Re: Losing rpm on takeoff |
Dave
Results is truly the main issue, no matter how you get them. If you want to
try to understand it later, take a ride in a certified plane with a constant
speed prop AKA variable pitch prop preferably hydraulic or electric actuated
as opposed to fly-weighted. Then you can adjust it on the ground to see the
effect or pitch. Then do it again in flight in acsending and descending
conditions. Now this prop is not like one found on the ultralites. Some
ultralite props can warp by design to achieve different effects that a
constant speed solid metal prop won't do so there is some difference.
Bruce
On Thu, Dec 2, 2010 at 2:51 PM, Dave G <occom@ns.sympatico.ca> wrote:
> I have received enough email to establish a plan of action here. Despite
> the fact that reducing pitch WILL result in an overspend situation with my
> particular experimental installation, I will reduce the pitch and see what
> happens during high speed taxi and then climb. Many people actually using
> Warp props tell me that I achieve the results I am looking for.
>
> I understand it is counter-intuitive, but apparently it is at least
> somewhat common. I have a couple of theories, but for now I'll accept
> positive results and remain in doubt about the actual reason. Over a long
> work life I've had to do that on many occasions, because results are what
> really matters.
>
> Thanks to Guy, Lucien and those who contributed positive and helpful advice
> off list. To those who offered unhelpful advice and lectures, thanks for the
> efforts. It all reminds me of a saying a friend repeats from time to time.
>
> "In theory, theory and practice are the same; in practice they are quite
> different!" This may be one of those cases.
>
> Dave Goddard
> KF IV 1050 / 582 / Warp
>
> ----- Original Message -----
> *From:* b d <gpabruce@gmail.com>
> *To:* kitfox-list@matronics.com
> *Sent:* Thursday, December 02, 2010 5:52 PM
> *Subject:* Re: Kitfox-List: Re: Losing rpm on takeoff
>
> Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
> cavitation and with an prop in air (an airfoil), it's called a stall but
> essentially the same-o same-o. We all know what is meant, we just have to
> be tolerent of each others linguistics. To be technical I really don't
> believe there is such a word as "un-stalling". It's either stalled or not
> stalled but correct me if I'm wrong. But I do not what you mean and what
> your getting at, it's like coming out of a stall condition.
>
> Bruce
>
>
> On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net>wrote:
>
>>
>> Mike,
>>
>> I think you answered your own question. Just substitute stalled prop for
>> cavitating prop. I think the concept is the same In each case the prop is
>> pitched too high for conditions.
>>
>> Lowell
>>
>> --------------------------------------------------
>> From: "mikeperkins" <michael.perkins@rauland.com>
>> Sent: Thursday, December 02, 2010 11:41 AM
>> To: <kitfox-list@matronics.com>
>> Subject: Kitfox-List: Re: Losing rpm on takeoff
>>
>>
>>> michael.perkins@rauland.com>
>>>
>>> I have never heard a discussion involving aircraft props that mentions
>>> cavitation, stirring air, humidity, or higher RPM during a static run-up. If
>>> you have some references, please let me know.
>>>
>>> A prop during a static run-up experiences a higher angle-of-attack than a
>>> prop moving forward through air. The higher AOA produces more drag, thus
>>> more load on the engine, and thus a lower RPM for a given power setting, not
>>> higher RPM.
>>>
>>> Some very high-performance aircraft with fixed-pitch props (long time
>>> ago) produced so little prop thrust (blade lift) during a static run-up that
>>> they had to be pushed to get them rolling - the prop was stalled. Once
>>> rolling, the AOA would gradually decrease and thrust (lift) would increase
>>> because the prop was un-stalling.
>>>
>>> A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a static
>>> run-up (temp dependent), and max RPM of 6600 while climbing at Vx.
>>>
>>> I would not be looking at the prop pitch for this particular problem.
>>>
>>> Mike
>>>
>>>
>>>
>>>
>>> Read this topic online here:
>>>
>>> http://forums.matronics.com/viewtopic.php?p=322085#322085
>>>
>>>
>>> m/" target="_blank">www.aeroelectric.com
>>> omebuiltHELP www.homebuilthelp.com
>>> http:/r generous support!
>>>
>>> ronics List Features Navigator to browse
>>> s.com/Navigator?Kitfox-List"
>>> target="_blank">http://www.matronics.com/Navigator?Kitfox-List<http://www.matronics.com/contribution>
>>> ronics.com/" target="_blank">http://forums.matronics.com
>>> =============
>>>
>>>
>>>
>>>
> *
>
> href="http://www.aeroelectric.com">www.aeroelectric.com
> href="http://www.buildersbooks.com">www.buildersbooks.com
> href="http://www.homebuilthelp.com">www.homebuilthelp.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?Kitfox-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com*
>
> *
>
>
Message 12
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| Subject: | drilling/tapping fiberglass tank |
Fiberglass tanks seem to be one of the really major sources of posts here. My
KF2, which I did not build, came to me with aluminum tanks which have never given
me any trouble at all. So two questions.
1. In light of all the problems, why does the whole world, it seems like, use fiberglass
tanks?
2. Are there any potential problems with aluminum tanks that I should know about?
How about steel tanks? I wonder how much weight they would really add over fiberglass.
Jim
KF2/582/Pahrump
Message 13
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| Subject: | Re: Losing rpm on takeoff |
Guess what I just ran across . . . a discussion about "prop cavitation on
takeoff". An interesting play on terminology again. Thought I would throw
this in to confuse the doubting Thomas's even more :-)
Bruce
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*Propeller cavitation?*
*Posted By:*
*[image: David Lacy]*<https://mail.google.com/ok365_UserProfile.aspx?uid=76531>
**
*David Lacy* <https://mail.google.com/ok365_UserProfile.aspx?uid=76531>* *
*Posted: 11/30/2010 15:15:08 *
*Hello every one! I am new to this forum but have read several threads with
some great info. I hope someone can help with my issue.*
*I purchased a mid 90s Rans S 12 XL with a Rotax 582 and a four blade Warp
Drive propeller about a year ago. Between me and my instructor, the plane
has about 45 hrs flying time since purchase. The plane and the engine have
performed flawlessly.*
*The issue occurs during acceleration for take off and occasionally early in
climb out. For a very brief moment (about 1 second or less) the engine will
over speed (my normal rpm during climb out is~6,300; it jumps to~6,700). *
*Or assumption is that the prop is cavitating due to disrupted air flow
around the engine and muffler. If anyone has knowledge of this or solutions,
I would be grateful. TIA
*
On Thu, Dec 2, 2010 at 3:48 PM, b d <gpabruce@gmail.com> wrote:
> Dave
>
> Results is truly the main issue, no matter how you get them. If you want to
> try to understand it later, take a ride in a certified plane with a constant
> speed prop AKA variable pitch prop preferably hydraulic or electric actuated
> as opposed to fly-weighted. Then you can adjust it on the ground to see the
> effect or pitch. Then do it again in flight in acsending and descending
> conditions. Now this prop is not like one found on the ultralites. Some
> ultralite props can warp by design to achieve different effects that a
> constant speed solid metal prop won't do so there is some difference.
>
> Bruce
>
>
> On Thu, Dec 2, 2010 at 2:51 PM, Dave G <occom@ns.sympatico.ca> wrote:
>
>
>> I have received enough email to establish a plan of action here. Despite
>> the fact that reducing pitch WILL result in an overspend situation with my
>> particular experimental installation, I will reduce the pitch and see what
>> happens during high speed taxi and then climb. Many people actually using
>> Warp props tell me that I achieve the results I am looking for.
>>
>> I understand it is counter-intuitive, but apparently it is at least
>> somewhat common. I have a couple of theories, but for now I'll accept
>> positive results and remain in doubt about the actual reason. Over a long
>> work life I've had to do that on many occasions, because results are what
>> really matters.
>>
>> Thanks to Guy, Lucien and those who contributed positive and helpful
>> advice off list. To those who offered unhelpful advice and lectures, thanks
>> for the efforts. It all reminds me of a saying a friend repeats from time to
>> time.
>>
>> "In theory, theory and practice are the same; in practice they are quite
>> different!" This may be one of those cases.
>>
>> Dave Goddard
>> KF IV 1050 / 582 / Warp
>>
>> ----- Original Message -----
>> *From:* b d <gpabruce@gmail.com>
>> *To:* kitfox-list@matronics.com
>> *Sent:* Thursday, December 02, 2010 5:52 PM
>> *Subject:* Re: Kitfox-List: Re: Losing rpm on takeoff
>>
>> Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
>> cavitation and with an prop in air (an airfoil), it's called a stall but
>> essentially the same-o same-o. We all know what is meant, we just have to
>> be tolerent of each others linguistics. To be technical I really don't
>> believe there is such a word as "un-stalling". It's either stalled or not
>> stalled but correct me if I'm wrong. But I do not what you mean and what
>> your getting at, it's like coming out of a stall condition.
>>
>> Bruce
>>
>>
>>
>>
>>
>>
>> On Thu, Dec 2, 2010 at 12:08 PM, Lowell Fitt <lcfitt@sbcglobal.net>wrote:
>>
>>
>>>
>>>
>>> Mike,
>>>
>>> I think you answered your own question. Just substitute stalled prop for
>>> cavitating prop. I think the concept is the same In each case the prop is
>>> pitched too high for conditions.
>>>
>>> Lowell
>>>
>>> --------------------------------------------------
>>> From: "mikeperkins" <michael.perkins@rauland.com>
>>> Sent: Thursday, December 02, 2010 11:41 AM
>>> To: <kitfox-list@matronics.com>
>>> Subject: Kitfox-List: Re: Losing rpm on takeoff
>>>
>>>
>>>
>>>> michael.perkins@rauland.com>
>>>>
>>>> I have never heard a discussion involving aircraft props that mentions
>>>> cavitation, stirring air, humidity, or higher RPM during a static run-up.
If
>>>> you have some references, please let me know.
>>>>
>>>> A prop during a static run-up experiences a higher angle-of-attack than
>>>> a prop moving forward through air. The higher AOA produces more drag, thus
>>>> more load on the engine, and thus a lower RPM for a given power setting, not
>>>> higher RPM.
>>>>
>>>> Some very high-performance aircraft with fixed-pitch props (long time
>>>> ago) produced so little prop thrust (blade lift) during a static run-up that
>>>> they had to be pushed to get them rolling - the prop was stalled. Once
>>>> rolling, the AOA would gradually decrease and thrust (lift) would increase
>>>> because the prop was un-stalling.
>>>>
>>>> A properly set-up Rotax 2-stroke will produce 5800 to 6200 on a static
>>>> run-up (temp dependent), and max RPM of 6600 while climbing at Vx.
>>>>
>>>> I would not be looking at the prop pitch for this particular problem.
>>>>
>>>> Mike
>>>>
>>>>
>>>>
>>>>
>>>> Read this topic online here:
>>>>
>>>> http://forums.matronics.com/viewtopic.php?p=322085#322085
>>>>
>>>>
>>>>
>>>> m/" target="_blank">www.aeroelectric.com
>>>> omebuiltHELP www.homebuilthelp.com
>>>> http:/r generous support! <http://www.matronics.com/contribution>
>>>> ronics List Features Navigator to browse
>>>>
>>>> s.com/Navigator?Kitfox-List"
>>>> target="_blank">http://www.matronics.com/Navigator?Kitfox-List<http://www.matronics.com/contribution>
>>>> ronics.com/" target="_blank">http://forums.matronics.com
>>>> =============
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>> *
>>
>> href="http://www.aeroelectric.com">www.aeroelectric.com
>> href="http://www.buildersbooks.com">www.buildersbooks.com
>> href="http://www.homebuilthelp.com">www.homebuilthelp.com
>> href="http://www.matronics.com/contribution">http://www.matronics.com/chref="http://www.matronics.com/Navigator?Kitfox-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com*
>>
>> *
>>
>>
>>
>
Message 14
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| Subject: | Re: Losing rpm on takeoff |
On 12/2/2010 1:52 PM, b d wrote:
> Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
> cavitation and with an prop in air (an airfoil), it's called a stall
> but essentially the same-o same-o.
OOO I LOVE semantics. Actually, cavitation is quite different from
stall. Cavitation involves a phase change from liquid to gas due to
pressure drop over the airfoil. Since the gas is compressible it vacates
the low pressure region of the airfoil destroying lift. Stall is where
the streamlines in the low pressure region depart catastrophically from
the airfoil surface. It can happen in liquids and well as gasses.
Stalling the liquid does not result in gas formation, or cavitation, but
results merely in turbulent flow. I used to do it in the sailboat all
the time.
Guy Buchanan
Kitfox IV-1200 / 592-C / Warp 3cs / 500 hrs.
Message 15
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| Subject: | Re: drilling/tapping fiberglass tank |
On 12/2/2010 4:03 PM, rez wrote:
> 1. In light of all the problems, why does the whole world, it seems like, use
fiberglass tanks?
>
Purely subjective answers:
* Easy to manufacture, particularly in compound shapes.
* Relatively light.
* Corrosion proof, fuel corrosion notwithstanding.
* Very high fatigue resistance.
> 2. Are there any potential problems with aluminum tanks that I should know about?
>
* Potential for fatigue failure, particularly at any attachments or
baffles.
* Corrosion due to water in the fuel.
* Corrosion due to water sitting below the fuel.
> How about steel tanks? I wonder how much weight they would really add over fiberglass.
>
Just a guess, but I'd say - lots. Quite a lot of aircraft, certificated
and otherwise, do just fine with aluminum tanks. I'd say stick with 'em.
Guy Buchanan
Kitfox IV-1200 / 592-C / Warp 3cs / 500 hrs.
Message 16
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| Subject: | Re: Losing rpm on takeoff |
Cavitation and stall are quite the same but with different mediums, it's
still only semantics. And yes a sail luffs too yet another analogy to
describe the same thing. Nothing new has been added. You only said the
same thing the first feller said a long time ago but yet another way. We all
get it. The horse is absolutely dead and has now been drug down the road
several miles . . . :-)
On Thu, Dec 2, 2010 at 10:44 PM, Guy Buchanan <gebuchanan@cox.net> wrote:
>
>
> On 12/2/2010 1:52 PM, b d wrote:
>
>> Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's called
>> cavitation and with an prop in air (an airfoil), it's called a stall but
>> essentially the same-o same-o.
>>
>
> OOO I LOVE semantics. Actually, cavitation is quite different from stall.
> Cavitation involves a phase change from liquid to gas due to pressure drop
> over the airfoil. Since the gas is compressible it vacates the low pressure
> region of the airfoil destroying lift. Stall is where the streamlines in the
> low pressure region depart catastrophically from the airfoil surface. It can
> happen in liquids and well as gasses. Stalling the liquid does not result in
> gas formation, or cavitation, but results merely in turbulent flow. I used
> to do it in the sailboat all the time.
>
> Guy Buchanan
> Kitfox IV-1200 / 592-C / Warp 3cs / 500 hrs.
>
>
Message 17
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| Subject: | Re: drilling/tapping fiberglass tank |
>1. In light of all the problems, why does the whole world, it seems
>like, use fiberglass tanks?
The explanation I heard from John McBean is that Kitfox and Avid
wings flex far too much for a rigid tank to withstand.
>2. Are there any potential problems with aluminum tanks that I
>should know about?
Yes, they come apart at the seams. Literally. Aircraft that use
aluminum tanks successfully have wing structures that are much
stiffer than the root area of the Kitfox/Avid wings.
Mike G.
N728KF, Kitfox IV-1200 Speedster
Phoenix, AZ
--
"My airplane is quiet, and for a moment still an alien, still a
stranger to the ground, I am home."
--Richard Bach
Message 18
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| Subject: | Re: Losing rpm on takeoff |
Bruce sez:
>Cavitation and stall are quite the same but with different mediums,
>it's still only semantics.
Guy's explanation shows clearly that this is NOT the case. From
Wikipedia <http://en.wikipedia.org/wiki/Cavitation>: "Cavitation is
the formation of vapor bubbles of a flowing liquid in a region where
the pressure of the liquid falls below its vapor pressure."
No mention of angle of attack or separation from a surface. And air
doesn't changing phases in a stall!
>You only said the same thing the first feller said a long time ago
>but yet another way. We all get it.
Apparently not... :-|
Mike G.
N728KF, Kitfox IV-1200 Speedster
Phoenix, AZ
>On Thu, Dec 2, 2010 at 10:44 PM, Guy Buchanan
><<mailto:gebuchanan@cox.net>gebuchanan@cox.net> wrote:
>
><<mailto:gebuchanan@cox.net>gebuchanan@cox.net>
>
>
>On 12/2/2010 1:52 PM, b d wrote:
>
>Yes, it's semantics, with a prop in a liquid (a hydrofoil) it's
>called cavitation and with an prop in air (an airfoil), it's called
>a stall but essentially the same-o same-o.
>
>
>OOO I LOVE semantics. Actually, cavitation is quite different from
>stall. Cavitation involves a phase change from liquid to gas due to
>pressure drop over the airfoil. Since the gas is compressible it
>vacates the low pressure region of the airfoil destroying lift.
>Stall is where the streamlines in the low pressure region depart
>catastrophically from the airfoil surface. It can happen in liquids
>and well as gasses. Stalling the liquid does not result in gas
>formation, or cavitation, but results merely in turbulent flow. I
>used to do it in the sailboat all the time.
>
>Guy Buchanan
>Kitfox IV-1200 / 592-C / Warp 3cs / 500 hrs.
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