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tonyplane(at)bellsouth.ne
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 Posted: Mon Dec 25, 2006 11:05 am Post subject: Nav antenna location?/200 mph |
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I do not see any problem getting to 200 mph IAS in the XL. During my Phase
I FLIGHT TEST . I took my XL (in a shallow to slightly steep dive while
monitoring RPM to keep my Jab below 3300 rpm) to 195 IAS to check that there
were no indications of any control buzz. It was a non-event, but something
I will not do again purposefully during normal flight. My Vne is 180 mph
/156 kts (below 1300 lbs gross) and 160 mph/140 kts (above 1300 lb gross wt)
It is very easy to go into the air speed "yellow" zone (148 mph /129 kts)
and approach the "red' line during decents with power to keep the cylinders
warm.
Tony Graziano
601XL/Jab3300A; N493TG; 187 hrs
.------------
Time: 09:12:01 AM PST US
| Quote: | Subject: Re: Nav antenna location?
From: "Gig Giacona" <wr.giacona(at)cox.net>
Screw the antenna. How did you get to 200MPH?
bryanmmartin wrote:
> I have a home-made VOR antenna mounted on top of the rudder on my XL.
> I have test flown the plane to 200MPH and have seen no hint of
> flutter. The antenna is mounted just forward of the rudder spar, so
> the balance change in the rudder is minimal.
--
Bryan Martin
N61BM, CH 601 XL,
RAM Subaru, Stratus redrive. |
--------
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=83388#83388
[/quote]
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Gig Giacona
Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA
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| Posted: Mon Dec 25, 2006 3:17 pm Post subject: Re: Nav antenna location?/200 mph |
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Well, I'm glad it worked out for you. The designer set the Vne at 180 and I really see no reason to exceed it.
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_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR |
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Terry Phillips
Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT
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| Posted: Mon Dec 25, 2006 11:19 pm Post subject: Nav antenna location?/200 mph |
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Tony
I am confused by the your relationship between Vne and gross weight.
My understanding is that Vne is 90% of the speed at which flutter occurs on
airfoil surfaces. It would seem to me that the relationship between speed
and flutter would depend primarily on the shape of the airfoils and
secondarily the angle of attack. It is not clear to me how having more
weight inside the airframe will change the speed at which flutter occurs,
particularly in an XL where sufficiently high speeds are only attainable in
a dive. Admittedly, the angle of attack in steady cruise has to be greater
at higher loadings. It's not clear to me how the angle of attack will
depend on gross weight in a dive. I do know that the C-150 and C-152 I have
been training in have only a single Vne.
I would like to know your thinking behind having two values for Vne.
Terry
At 01:04 PM 12/25/2006 -0600, you wrote:
| Quote: | I do not see any problem getting to 200 mph IAS in the XL. During my
Phase I FLIGHT TEST . I took my XL (in a shallow to slightly steep dive
while monitoring RPM to keep my Jab below 3300 rpm) to 195 IAS to check
that there were no indications of any control buzz. It was a non-event,
but something I will not do again purposefully during normal flight. My
Vne is 180 mph /156 kts (below 1300 lbs gross) and 160 mph/140 kts (above
1300 lb gross wt)
It is very easy to go into the air speed "yellow" zone (148 mph /129 kts)
and approach the "red' line during decents with power to keep the
cylinders warm.
Tony Graziano
601XL/Jab3300A; N493TG; 187 hrs
|
Terry Phillips
ttp44(at)rkymtn.net
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_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings. |
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amyvega2005(at)earthlink.
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| Posted: Tue Dec 26, 2006 5:52 am Post subject: Nav antenna location?/200 mph |
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stall rate increases as as weight in the plane increases. that is why after 1320 to 1400 lbs the plane wants to fly but can't. the plane cannot get enough speed to keep the wings flyin. vne is 90% OF FLUTTER OR STALL OCURS, if the weigh goes up, the wing will flutter and stall at higher speed. if you weigh the plane down with too much weight, the wings can come right off with the slightest turn. thats the extreme, because the weight has to change direction with the direction of the plane and the heavier the object that wants to turn, the greater the load on the structure has it starts the turn and throughout the turn. so if loaded up past max gross, in a turn the wing load will be at its apex, takng on greater Gs, stalling quicker.
Vne stays the same, stall speed goes up. In some jets that fly high enough, stall speed is within 2 knots of cruise speed.
Happy Christnukha
Juan Vega 601xl
--
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amyvega2005(at)earthlink.
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| Posted: Tue Dec 26, 2006 6:05 am Post subject: Nav antenna location?/200 mph |
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to addmy previous response to the dude's question on Vne, most planes that are aerobatic, are certified to fly unusual attitudes only below a certain weight. Vans aircraft have a posted sign that says to limit the weight to a certain amount before unusual attitude flying, same for most. Even Extra 300s go up with 1/4 tanks of gas, because the plane performs totally differently at gross. Same for CH 601. It is loaded for 6 gs below gross. go loaded up and you fold the wings at take off.
Juan
--
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Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
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| Posted: Tue Dec 26, 2006 6:38 am Post subject: Nav antenna location?/200 mph |
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I heartily agree. There has been more than one accident caused by exceeding the VNE.
Noel
Happy New Year!
| Quote: | Well, I'm glad it worked out for you. The designer set the
> Vne at 180 and I really see no reason to exceed it.
|
[quote] [quote][b]
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Noel Loveys
Kitfox III-A
Aerocet 1100 Floats |
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tonyplane(at)bellsouth.ne
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| Posted: Tue Dec 26, 2006 7:05 am Post subject: Nav antenna location?/200 mph |
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Terry,
Good question.
The Vne on my plans (dwgs dated 06/03) is 180 mph. and gross wt is 1300
lbs. Dwg change #3 established a gross wt of 1320 lbs with a Vne of 160
mph. I recall asking Zenith about the change to Vne and if I recall the
answer was a Vne of 180 is ok at 1320 gross wt if I have cargo in my wing
lockers. I assumed the change in Vne was for g loading under rapid stick
deflection. I took it to a little less than 110% max Vne IAS. I did not do
any excitation of the control surfaces at that speed other than a smooth
pull out. I approached that speed in a series of increasing speeds during
my Phase I testing.
I have not gone into the "red line" since test flight, but I do have
confidence in the integrity of the XL airframe should I somehow
inadvertently wifferdill* into some unusual nose down attitude.
It appears that some doubt that the XL can do 200 mph.even at terminal
velocity. I have no idea what the terminal velocity of the XL might be and
do not plan to find out.
* "Technical" term for an uncontrolled/unexpected departure or a "what the
(at)#$&"
Tony
| Quote: |
Time: 11:19:48 PM PST US
From: Terry Phillips <ttp44(at)rkymtn.net>
Subject: Re: Re: Nav antenna location?/200 mph
Tony
I am confused by the your relationship between Vne and gross weight.
My understanding is that Vne is 90% of the speed at which flutter occurs
on
airfoil surfaces. It would seem to me that the relationship between speed
and flutter would depend primarily on the shape of the airfoils and
secondarily the angle of attack. It is not clear to me how having more
weight inside the airframe will change the speed at which flutter occurs,
particularly in an XL where sufficiently high speeds are only attainable
in
a dive. Admittedly, the angle of attack in steady cruise has to be greater
at higher loadings. It's not clear to me how the angle of attack will
depend on gross weight in a dive. I do know that the C-150 and C-152 I
have
been training in have only a single Vne.
I would like to know your thinking behind having two values for Vne.
Terry
At 01:04 PM 12/25/2006 -0600, you wrote:
>I do not see any problem getting to 200 mph IAS in the XL. During my
>Phase I FLIGHT TEST . I took my XL (in a shallow to slightly steep dive
>while monitoring RPM to keep my Jab below 3300 rpm) to 195 IAS to check
>that there were no indications of any control buzz. It was a non-event,
>but something I will not do again purposefully during normal flight. My
>Vne is 180 mph /156 kts (below 1300 lbs gross) and 160 mph/140 kts (above
>1300 lb gross wt)
>It is very easy to go into the air speed "yellow" zone (148 mph /129 kts)
>and approach the "red' line during decents with power to keep the
>cylinders warm.
>
>Tony Graziano
>601XL/Jab3300A; N493TG; 187 hrs
Terry Phillips
ttp44(at)rkymtn.net
|
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Terry Phillips
Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT
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| Posted: Wed Dec 27, 2006 5:17 am Post subject: Nav antenna location?/200 mph |
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Tony
Thank you for the reply. That sounds like a reasonable way to proceed,
given the info from ZAC. I suspect they increased the gross to 1320 in
response to the release of sport aircraft limits (no doubt as a result of
static load tests). But, I'd like to know why they changed the Vne.
I am confident that the XL at 160 mph is well within it's safety envelope,
but excessive wing load is a serious matter, see "Faulty ADM Kills" in
http://overtheairwaves.com/vol3-20final.html
for an extreme example of the consequences.
Terry
At 09:04 AM 12/26/2006 -0600, you wrote:
| Quote: | Terry,
Good question.
The Vne on my plans (dwgs dated 06/03) is 180 mph. and gross wt is 1300
lbs. Dwg change #3 established a gross wt of 1320 lbs with a Vne of 160
mph. I recall asking Zenith about the change to Vne and if I recall the
answer was a Vne of 180 is ok at 1320 gross wt if I have cargo in my wing
lockers. I assumed the change in Vne was for g loading under rapid stick
deflection. I took it to a little less than 110% max Vne IAS. I did not
do any excitation of the control surfaces at that speed other than a
smooth pull out. I approached that speed in a series of increasing speeds
during my Phase I testing.
I have not gone into the "red line" since test flight, but I do have
confidence in the integrity of the XL airframe should I somehow
inadvertently wifferdill* into some unusual nose down attitude.
It appears that some doubt that the XL can do 200 mph.even at terminal
velocity. I have no idea what the terminal velocity of the XL might be
and do not plan to find out.
* "Technical" term for an uncontrolled/unexpected departure or a "what the
(at)#$&"
Tony
|
Terry Phillips
ttp44(at)rkymtn.net
| | - The Matronics Zenith-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Zenith-List |
|
_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings. |
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