Today's Message Index:
----------------------
1. 01:13 AM - 601 exhaust movement (Richard McLachlan)
2. 07:52 AM - Re: Crash 701- another one (Carl Bertrand)
3. 09:06 AM - Re: N701XL Flies! (JERICKSON03E@aol.com)
4. 09:09 AM - Re: Crash 701- another one (Dirk Slabbert)
5. 09:26 AM - Re: Crash 701- another one (Steve Dixon)
6. 12:03 PM - Re: N701XL Flies! (Dabusmith@aol.com)
7. 06:07 PM - New 5th Edition HD/HDS Drawings! (Doug Waer)
Message 1
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| Subject: | 601 exhaust movement |
We have a 601HDS with the Rotax 912 engine. When we bought the a/c the
original builder had fitted his own stainless steel exhaust system, which had
no baffles in the silencer (muffler). Due to noise complaints, we replaced this
with the original Zenith exhaust with the dual spring retained couplings.
Problem is that with use one of the exhaust pipes gradually vibrates its way
toward the cowling until it starts hitting against it. We already have the
securing bolt as tight as we dare go without stripping the thread.
--> Zenith-List message posted by: Richard McLachlan <richard@rodsley.net>
Does anybody know any reason why we should not fit a pair of SS securing
straps from each silencer body to a central point under the engine? This
would prevent the movement but may also prevent the spring couplings
moving.
--
Richard McLachlan
CH601HDS/R22
Helicopter Landing Site info at http://www.rodsley.net
Message 2
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| Subject: | Re: Crash 701- another one |
--> Zenith-List message posted by: "Carl Bertrand" <cgbrt@mondenet.com>
Hi Rick,
I was sorry to read about your accident. I hope you recover fully from your
injuries and will again take to the air chalking the event to experience.
I took particular interest in your accident because I also fly a 701. I
scratch built in 94/95 and have over three hundred hours mostly on floats;
half with the ZAC wings and half with my own design auto slat wings (very
similar to the dedalius design). In my case I find handling to be very
similar with both designs and in my opinion the differences were not a
factor in your accident.
Before I committed to building my new wing I did a long series of test on a
6' full scale section with slat and flap. With tufts in place, I video
recorded air flow at all angles of attack from 0 to 30 and with the flaps at
0,15, 30 degrees. I conducted these test with the slat "in", "out", and
"free" at speeds up to 50 mph. For me the results were very informative and
gave me the confidence I needed to proceed with building and flight testing
the wings. I must state that although I have not flown the dedalius wings, I
can state with assurance that the flight characteristics of the ZAC and my
design are much the same and suspect that the dedalius wing is also similar.
The wing design in the 701 with slats and displaced flaps is optimized to
develop very high lift at slow speed. The effect of the slots at the slats
and the flaps results in stall angles in the 30 degree range as opposed to
the more conventional wing at 17 degrees. Also, the elevator is optimized to
be very effective for its size. This makes the a/c very manoeuvrable at low
speed but like all a/c it has its limits.
From your description of the accident, you only rolled "three to four
meters" when the a/c rotated rapidly, became airborne, continued rotation to
a steep angle, "tea bag", and then "went into a descent to the left from
about 70 feet". In my opinion, I believe the a/c responded to the very
strong control forces applied; mainly from the stab/elevator . With full
power, the air flow over the full "UP" elevator caused the a/c to rotate
early and rapidly changing the angle angle of attack from around 8 to
somewhere greater than 25 degrees. As others have pointed out you became
airborne prematurely because of ground effect but also the high lift wing
design.
Things would develop very quickly from that point for a number of reasons.
At the approach of the critical angle we all know that lift quickly changes
to drag. With this wing a lot of lift changes into a lot of drag. From my
experiments, I found that the last areas to stall are behind the slots
(Behind the slat to the main spar, and the flap). The flap continues to
produce lift even when down 30 degrees and wing angle of attack is 28
degrees. However, once you're in that position you no longer have a high
lift wing; you have a very effective speed brake.
If you picture the a/c in that 30 degree position from the side, the drag
vector from the wing is high and towards the front trying to rotate the a/c
further. If you still had "UP"or even neutral elevator it accentuated the
pitch-up because of its effecient inverted airfoil design. In addition, the
rapid rotation at the start created momentum adding to the tendency to over
rotate. Some of the forces that would help countered the rotation were: The
lost of lift from the stalled wing; flying out of ground effect once above
15 to 20'; C of G; and ,any "down" elevator you applied. Once you rapidly
passed through the 20 to 25 degree angle of attack, I don' believe the
outcome could be changed much by any control inputs and only engine thrust
could cushion the return to mother earth. In my experience 200 to 300
hundred feet would be needed to recover.
After much experimentation, I've found that the following gives me the best
short take-off performance. Take-off flaps, (25 degrees in my case)
controls neutral, max RPM against the brakes, release brakes and accelerate
to 20-25 mph then fairly smart back elevator until the nose starts to rise.
Be prepared to rapidly check forward to stop rotation at 20-25 degrees.Once
off the ground the a/c accelerates fairly quickly and you must feed in
forward elevator to maintain the angle from increasing into a stall. At that
stage I normally let the speed increase and reduce flaps to 10 degrees
before climbing out of ground effect. If end of runway obstacle are a
problem I keep flaps at 20 until clear.
My only excuse for this long reply is that writing is not my strong suit.
Best wishes for the rebuild.
Carl
----- Original Message -----
From: "Rick Morawski" <morawski@highway1.com.au>
Subject: Re: Zenith-List: Crash 701- another one
> --> Zenith-List message posted by: "Rick Morawski"
<morawski@highway1.com.au>
>
Message 3
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| Subject: | Re: N701XL Flies! |
--> Zenith-List message posted by: JERICKSON03E@aol.com
Dave, Great job. Fly safely & enjoy.
Jerry Erickson
701SP in work
Message 4
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| Subject: | Re: Crash 701- another one |
--> Zenith-List message posted by: "Dirk Slabbert" <dslabbert@worldonline.co.za>
Carl, your post is really an eye opener, shakes out all the cobwebs!
Thanks, it will probably keep me out of harms way, or my bones from the lions mouth.......he
hee hee..
Dirk (bush pilot in Africa)
----- Original Message -----
From: Carl Bertrand
To: zenith-list@matronics.com
Sent: Sunday, November 02, 2003 5:53 PM
Subject: Re: Zenith-List: Crash 701- another one
--> Zenith-List message posted by: "Carl Bertrand" <cgbrt@mondenet.com>
Hi Rick,
I was sorry to read about your accident. I hope you recover fully from your
injuries and will again take to the air chalking the event to experience.
I took particular interest in your accident because I also fly a 701. I
scratch built in 94/95 and have over three hundred hours mostly on floats;
half with the ZAC wings and half with my own design auto slat wings (very
similar to the dedalius design). In my case I find handling to be very
similar with both designs and in my opinion the differences were not a
factor in your accident.
Before I committed to building my new wing I did a long series of test on a
6' full scale section with slat and flap. With tufts in place, I video
recorded air flow at all angles of attack from 0 to 30 and with the flaps at
0,15, 30 degrees. I conducted these test with the slat "in", "out", and
"free" at speeds up to 50 mph. For me the results were very informative and
gave me the confidence I needed to proceed with building and flight testing
the wings. I must state that although I have not flown the dedalius wings, I
can state with assurance that the flight characteristics of the ZAC and my
design are much the same and suspect that the dedalius wing is also similar.
The wing design in the 701 with slats and displaced flaps is optimized to
develop very high lift at slow speed. The effect of the slots at the slats
and the flaps results in stall angles in the 30 degree range as opposed to
the more conventional wing at 17 degrees. Also, the elevator is optimized to
be very effective for its size. This makes the a/c very manoeuvrable at low
speed but like all a/c it has its limits.
From your description of the accident, you only rolled "three to four
meters" when the a/c rotated rapidly, became airborne, continued rotation to
a steep angle, "tea bag", and then "went into a descent to the left from
about 70 feet". In my opinion, I believe the a/c responded to the very
strong control forces applied; mainly from the stab/elevator . With full
power, the air flow over the full "UP" elevator caused the a/c to rotate
early and rapidly changing the angle angle of attack from around 8 to
somewhere greater than 25 degrees. As others have pointed out you became
airborne prematurely because of ground effect but also the high lift wing
design.
Things would develop very quickly from that point for a number of reasons.
At the approach of the critical angle we all know that lift quickly changes
to drag. With this wing a lot of lift changes into a lot of drag. From my
experiments, I found that the last areas to stall are behind the slots
(Behind the slat to the main spar, and the flap). The flap continues to
produce lift even when down 30 degrees and wing angle of attack is 28
degrees. However, once you're in that position you no longer have a high
lift wing; you have a very effective speed brake.
If you picture the a/c in that 30 degree position from the side, the drag
vector from the wing is high and towards the front trying to rotate the a/c
further. If you still had "UP"or even neutral elevator it accentuated the
pitch-up because of its effecient inverted airfoil design. In addition, the
rapid rotation at the start created momentum adding to the tendency to over
rotate. Some of the forces that would help countered the rotation were: The
lost of lift from the stalled wing; flying out of ground effect once above
15 to 20'; C of G; and ,any "down" elevator you applied. Once you rapidly
passed through the 20 to 25 degree angle of attack, I don' believe the
outcome could be changed much by any control inputs and only engine thrust
could cushion the return to mother earth. In my experience 200 to 300
hundred feet would be needed to recover.
After much experimentation, I've found that the following gives me the best
short take-off performance. Take-off flaps, (25 degrees in my case)
controls neutral, max RPM against the brakes, release brakes and accelerate
to 20-25 mph then fairly smart back elevator until the nose starts to rise.
Be prepared to rapidly check forward to stop rotation at 20-25 degrees.Once
off the ground the a/c accelerates fairly quickly and you must feed in
forward elevator to maintain the angle from increasing into a stall. At that
stage I normally let the speed increase and reduce flaps to 10 degrees
before climbing out of ground effect. If end of runway obstacle are a
problem I keep flaps at 20 until clear.
My only excuse for this long reply is that writing is not my strong suit.
Best wishes for the rebuild.
Carl
----- Original Message -----
From: "Rick Morawski" <morawski@highway1.com.au>
To: <zenith-list@matronics.com>
Subject: Re: Zenith-List: Crash 701- another one
> --> Zenith-List message posted by: "Rick Morawski"
<morawski@highway1.com.au>
>
Message 5
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| Subject: | Re: Crash 701- another one |
--> Zenith-List message posted by: "Steve Dixon" <dix39@charter.net>
Carl,
I think you should reassess your last statement, that was (IMHO) beautifully
done and VERY informative. I have printed it to use when my 701 is done and
flying. THANKS!!
Steve Dixon
DO NOT ARCHIVE
----- Original Message -----
From: "Carl Bertrand" <cgbrt@mondenet.com>
Subject: Re: Zenith-List: Crash 701- another one
> --> Zenith-List message posted by: "Carl Bertrand" <cgbrt@mondenet.com>
>
> Hi Rick,
> I was sorry to read about your accident. I hope you recover fully from
your
> injuries and will again take to the air chalking the event to experience.
> I took particular interest in your accident because I also fly a 701. I
> scratch built in 94/95 and have over three hundred hours mostly on floats;
> half with the ZAC wings and half with my own design auto slat wings (very
> similar to the dedalius design). In my case I find handling to be very
> similar with both designs and in my opinion the differences were not a
> factor in your accident.
> Before I committed to building my new wing I did a long series of test on
a
> 6' full scale section with slat and flap. With tufts in place, I video
> recorded air flow at all angles of attack from 0 to 30 and with the flaps
at
> 0,15, 30 degrees. I conducted these test with the slat "in", "out", and
> "free" at speeds up to 50 mph. For me the results were very informative
and
> gave me the confidence I needed to proceed with building and flight
testing
> the wings. I must state that although I have not flown the dedalius wings,
I
> can state with assurance that the flight characteristics of the ZAC and my
> design are much the same and suspect that the dedalius wing is also
similar.
> The wing design in the 701 with slats and displaced flaps is optimized to
> develop very high lift at slow speed. The effect of the slots at the slats
> and the flaps results in stall angles in the 30 degree range as opposed to
> the more conventional wing at 17 degrees. Also, the elevator is optimized
to
> be very effective for its size. This makes the a/c very manoeuvrable at
low
> speed but like all a/c it has its limits.
> From your description of the accident, you only rolled "three to four
> meters" when the a/c rotated rapidly, became airborne, continued rotation
to
> a steep angle, "tea bag", and then "went into a descent to the left from
> about 70 feet". In my opinion, I believe the a/c responded to the very
> strong control forces applied; mainly from the stab/elevator . With full
> power, the air flow over the full "UP" elevator caused the a/c to rotate
> early and rapidly changing the angle angle of attack from around 8 to
> somewhere greater than 25 degrees. As others have pointed out you became
> airborne prematurely because of ground effect but also the high lift wing
> design.
> Things would develop very quickly from that point for a number of reasons.
> At the approach of the critical angle we all know that lift quickly
changes
> to drag. With this wing a lot of lift changes into a lot of drag. From my
> experiments, I found that the last areas to stall are behind the slots
> (Behind the slat to the main spar, and the flap). The flap continues to
> produce lift even when down 30 degrees and wing angle of attack is 28
> degrees. However, once you're in that position you no longer have a high
> lift wing; you have a very effective speed brake.
> If you picture the a/c in that 30 degree position from the side, the drag
> vector from the wing is high and towards the front trying to rotate the
a/c
> further. If you still had "UP"or even neutral elevator it accentuated the
> pitch-up because of its effecient inverted airfoil design. In addition,
the
> rapid rotation at the start created momentum adding to the tendency to
over
> rotate. Some of the forces that would help countered the rotation were:
The
> lost of lift from the stalled wing; flying out of ground effect once above
> 15 to 20'; C of G; and ,any "down" elevator you applied. Once you rapidly
> passed through the 20 to 25 degree angle of attack, I don' believe the
> outcome could be changed much by any control inputs and only engine thrust
> could cushion the return to mother earth. In my experience 200 to 300
> hundred feet would be needed to recover.
> After much experimentation, I've found that the following gives me the
best
> short take-off performance. Take-off flaps, (25 degrees in my case)
> controls neutral, max RPM against the brakes, release brakes and
accelerate
> to 20-25 mph then fairly smart back elevator until the nose starts to
rise.
> Be prepared to rapidly check forward to stop rotation at 20-25
degrees.Once
> off the ground the a/c accelerates fairly quickly and you must feed in
> forward elevator to maintain the angle from increasing into a stall. At
that
> stage I normally let the speed increase and reduce flaps to 10 degrees
> before climbing out of ground effect. If end of runway obstacle are a
> problem I keep flaps at 20 until clear.
> My only excuse for this long reply is that writing is not my strong suit.
> Best wishes for the rebuild.
> Carl
>
>
> ----- Original Message -----
> From: "Rick Morawski" <morawski@highway1.com.au>
> To: <zenith-list@matronics.com>
> Subject: Re: Zenith-List: Crash 701- another one
>
>
> > --> Zenith-List message posted by: "Rick Morawski"
> <morawski@highway1.com.au>
> >
>
>
Message 6
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| Subject: | Re: N701XL Flies! |
--> Zenith-List message posted by: Dabusmith@aol.com
Jerry
Thanks for the kind words! This plane is great fun. It is snowing here today
so I haven't been able to fly it.
Get building!
Dave
Message 7
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| Subject: | New 5th Edition HD/HDS Drawings! |
--> Zenith-List message posted by: Doug Waer <dwaer@yahoo.com>
Was poking aroung the Zenith site, and noticed that they JUST updated the
HD/HDS drawings to a 5th edition last friday (10/31). This should put to rest
the whole idea that Zenith was essentially end-of-life'ing the HD/HDS series in
favor of the XL. The drawings can be updated for $50. Heck, I'd get an update
if for no other reason that my drawings have taken quite a beating in the last
year!
Doug Waer
601HDS
=====
Douglas Waer :: Boeing Helicopter Systems :: Mesa, AZ :: 85215
http://members.cox.net/dwaer/flying.html
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