Today's Message Index:
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1. 02:34 AM - Re: Losing rpm on takeoff (Dave G)
2. 02:41 AM - Re: Losing rpm on takeoff (Dave G)
3. 05:35 AM - Losing rpm on takeoff (fox5flyer)
4. 06:06 AM - Re: Prop pitch (Jeffrey Dill)
5. 09:07 AM - Re: Prop pitch (mikeperkins)
6. 01:24 PM - Re: Losing rpm on takeoff (rawheels)
7. 05:13 PM - drilling/tapping fiberglass tank (carlisle)
8. 06:32 PM - Re: drilling/tapping fiberglass tank (Lynn Matteson)
9. 07:53 PM - Re: drilling/tapping fiberglass tank (carlisle)
10. 08:49 PM - Re: Re: drilling/tapping fiberglass tank (Lynn Matteson)
Message 1
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| Subject: | Re: Losing rpm on takeoff |
My retired engine ran well beyond it's time and still looks like new using
that gauge package. I have a digital instrument upgrade in mind, they are
better, but mine have served well.
Dave Goddard
KF IV 1050 / 582 / Warp
----- Original Message -----
From: "Lynn Matteson" <lynnmatt@jps.net>
Sent: Tuesday, November 30, 2010 11:28 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)
>
>
Message 2
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| Subject: | Re: Losing rpm on takeoff |
But even with that your rpm went up from static not down, which is what
I am experiencing. Tiny tachs have their issues also, especially the
older ones. Try wrapping too much of the sense lead onto the HT lead,
they hate that!.
Dave Goddard
KF IV 1050 / 582 / Warp
----- Original Message -----
From: Noel Loveys
To: kitfox-list@matronics.com
Sent: Tuesday, November 30, 2010 10:31 PM
Subject: RE: Kitfox-List: Losing rpm on takeoff
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.
Message 3
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| Subject: | Losing rpm on takeoff |
Elbie, I think what you are experiencing is prop cavitation. This
happens at static when the prop gets the air stirred up and "slips"
through disturbed air, sort of like stalling, which increases the rpms.
On takeoff roll and climbout the prop is now spinning through clean air
which gives it more "grab", depending on the amount of pitch, which
reduces the rpms. Of course, the type and model of prop, along with
pitch, temperature, humidity, other factors has a role in this.
Deke Morisse
NE Mi and snowing
S5
Time: 01:45:18 PM PST US
From: EMAproducts@aol.com
Subject: Kitfox-List: Re: Jeffery Dill RPM - 11/29/10
In a message dated 11/30/2010 12:05:38 A.M. Pacific Standard Time,
kitfox-list@matronics.com writes:
I took off about a 1 1/2 degrees from my prop and ran it up to just
short
of 6600
RPM at full throttle. Then I went to fly, and once again, I saw much
less
during
takeoff roll, maybe 6100. In cruise at wide open throttle and level I
saw
a higher RPM, 6400. So, at least the static versus cruise RPMs make
more
sense
this time. I don't know why I twice have gotten a higher RPM right
after
installation
test than later flight test. Different conditions of some type, but
not
Remember, ANY change in Density Altitude will change the perceived power
output from your engine. This goes for 2 stroke, 4 stroke, turboprop
and
pure jet. Write down the temp and altitude when doing tests, then
compare,
you will find what a difference it makes.
Elbie
an old CFI, still teaching.
Message 4
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I have now seen the whole video and have learned a lot. While my temps have all
been below max, I would say my EGTs were below what I used to see with my old
prop, correlating with the higher pitch and consequent higher engine load. The
video suggests that such high load is seen on CHT. If I have it right, detonation
(a very very bad thing that can fail your engine in seconds) can occur in
two cases. Under high loading, probably more extreme than mine currently and
seen on CHT, you can get pinging the same way you might by trying to start a
car up hill in 5th gear. The other way to get it is by underloading , such as
descent in the 5000 rpm range where EGTs get up toward 1200. This is happening
because of relatively high rpm for the mixture, which translates to a lean mixture,
which further translates to detonation. As I type this I wonder if I have
that correct. Is detonation a consequence of that lean mixture, or just extremely
high temps? That point is academic because either way metal is melted and
engines can fail within seconds.
My goal is to match Tom's numbers by further reducing my pitch. Said another way,
my goal is to match Rotax numbers for normal operation. My take-away from this
is that adjustable pitch propellers are not so much to give us the option
to choose climb or cruise prop, rather, it is to provide a way to properly match
the prop to the engine, gearbox, and airplane.
As is pointed out in this video, there are ways to get more power out of the engine
with aftermarket devices, but these improve one regime at the expense of
another. The engine might provide more power for takeoff, but blow up in cruise.
My plan is to stick to the Rotax parameters as closely as I can. They have
given this a lot of thought. Now that I said that, it was pointed out in the video
that some of the guidelines cater to the weakest link, such as changing spark
plugs at 25 hours. They assure us that if we run the engine right, it will
not build up carbon or foul plugs. He did say he runs premium car gas, despite
Rotax ok for regular.
--------
Jeff Dill
Model 2
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321908#321908
Message 5
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Hi Jeff,
Glad you were able to watch the rest of the webinar video. In all my years flying
behind a 2-cycle, it is the single-most valuable source I've found for setting
up a prop. Your last post indicates some scientific thinking on your part.
And your take-away is exactly right. It is something that I had not thought about
consciously myself, but the goal is to match the engine's needs for reliable
performance, not optimizing for cruise or climb or some other thing. I like
that.
Regarding detonation, you won't experience it if things are set up more or less
correctly. I see 1160 - 1180 in cruise, but I don't worry if I see 1200 for a
short time.
EGTs are funny gauges. Westach's are calibrated at 75 degrees ambient. If the gauge
in the cockpit is colder, the EGT reads higher by the difference. So at 20
degrees, if the gauge reads 1000, the EGT probe is actually 1055. Conversely,
at 95 degrees ambient, a 1000 EGT is only 980. There are compensated EGT gauges,
but they're more expensive and usually digital.
I used to change the plugs religiously in my 532 at 25 hours or less. At 25 hours,
they always "read" very normal and showed no insulator carbon build-up or
electrode wear whatsoever - both could cause misfire. I now believe the thing
to do is to just keep an eye on them.
At one time, I was tempted to add the mixture-adjust modification to the carbs.
I even considered at one time trying an in-flight adjustable prop in the spirit
of being "experimental" to eek out some more performance. But after watching
the webinar, I feel that either of them would be asking for trouble.
When I built my panel, I put the EGT in front of me, just to the left of the ASI,
because I'd heard so much about the importance of EGT in 2-cycle engines. In
retrospect, think that was the right thing to do. It certainly keeps my focus
on the right engine parameter. I now have an ambient-compensated dual digital
EGT with a bright red warning light set for 1220. Even still, the video taught
me to not reduce power if the EGT gets excessive, but rather to load up the
engine by climbing until the power can be reduced slowly - very good to know.
Mike
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321932#321932
Message 6
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| Subject: | Re: Losing rpm on takeoff |
In case none of the other ideas help you, you might check your fuel lines for any
crimped or black rubber tubing. I had a problem with my model IV where about
halfway through the takeoff roll it would lose a couple hundred RPM. Finally
found that the problem was a ~2" piece of black rubber tubing that connected
the header tank to the metal fuel lines. After removing it, it swelled completely
shut. So while it was attached to the lines it was spread open allowing
enough fuel to get through to run continuously at about 6000 RPM, but no more.
I suppose the reason I could get a little bit down the runway was because
there was enough fuel in the carb bowls/lines to get that far before the "reduction"
metered the fuel.
--------
Ryan Wheeler
Kitfox IV-1200
Indianapolis, IN
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321958#321958
Message 7
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| Subject: | drilling/tapping fiberglass tank |
I'm going to install a clear sight tube so I can keep better track of fuel in my
older Model 2. Looking into partially opaque inside wall of tank just doesn't
hack it, especially when the fuel is low and the butt rib and some cockpit
tubing are in the way.
So, I'll empty the tank and tap in a couple of fittings. How's the best way to
keep the drill filings out of the tank?
Chris Carlisle
Model 2, 582, C box, Ivo light
Sioux Falls, SD
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322002#322002
Message 8
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| Subject: | Re: drilling/tapping fiberglass tank |
I would use a heavy grease smeared into the flutes of the drill to
contain most of the shavings/drillings/chips. When I did a similar
job recently, I used an old sandblasting nozzle to suck the crap out
of the tank right after drilling and tapping. The rest can be found
in your fuel filters (I prefer Purolator glass filters...over 1000
hours on the ones in my plane). Have you thickened the walls of the
tank(s) with fiberglass? They aren't very thick to begin with, so
just drilling and tapping isn't going to give you much to bite into,
if your tank(s) is anything like the one(s) in the Model IV.
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 Dec 1, 2010, at 8:10 PM, carlisle wrote:
>
> I'm going to install a clear sight tube so I can keep better track
> of fuel in my older Model 2. Looking into partially opaque inside
> wall of tank just doesn't hack it, especially when the fuel is low
> and the butt rib and some cockpit tubing are in the way.
>
> So, I'll empty the tank and tap in a couple of fittings. How's the
> best way to keep the drill filings out of the tank?
>
> Chris Carlisle
> Model 2, 582, C box, Ivo light
> Sioux Falls, SD
>
>
Message 9
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| Subject: | Re: drilling/tapping fiberglass tank |
Thanks Lynn. I hadn't considered the wall thickness of the tank but what you say
makes sense. If you can see the fuel level, it must be pretty thin. How'd
you do it? Did you just slather on some epoxy or something a little more refined?
Chris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=322017#322017
Message 10
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| Subject: | Re: drilling/tapping fiberglass tank |
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 like using the 5:1 pumps of the West System. You have to
have some fiberglass mat or cloth, and not just use a buildup of the
epoxy. This gives the epoxy something to stick to, and prevents it
from just running off the tank. A little flox in the mixture will
also stiffen the epoxy and prevent run-off. Using this method, I was
able to tap the area on my tanks out to 3/8 NPT for installation of
finger strainers...this was for front fuel ports on my IV.
I was just looking at a post I made concerning this same operation on
Nov. 25, and I had said that I tapped them to 1/4 NPT...that was the
size of the inside of the finger strainer, but the outside of the
finger strainer was in fact 3/8 NPT. Those threads are quite coarse,
so you really need to build up some thickness in order to get several
threads into the side of the tank.
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 Dec 1, 2010, at 10:35 PM, carlisle wrote:
>
> Thanks Lynn. I hadn't considered the wall thickness of the tank
> but what you say makes sense. If you can see the fuel level, it
> must be pretty thin. How'd you do it? Did you just slather on
> some epoxy or something a little more refined?
>
> Chris
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=322017#322017
>
>
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