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VNE on a mod 4 1200 (was New Member)

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wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Mon Mar 20, 2006 5:52 am Post subject: VNE on a mod 4 1200 (was New Member)

Why is your VNE so much higher than mine? The red on my speedo starts at 125. I always found it kinda scary to have a cruise speed that is only 10mph slower than VNE. If I get any kind of updraft, I have to ride it out and let her climb. If I try to hold altitude without working the trottle she'll blow right by VNE in a jiffy.

 	  Quote: 	
		  Your numbers seem fine, Kirk. My Model IV-1200 Speedster weighed in at 660 pounds with a 100 HP Rotax 912ULS and Ivo medium prop. After I installed the wheel pants she could hit Vne (140 mph) in level flight with full power. High speed cruise was around 125 mph at 5.5 

gph or a more sedate 115 mph at 5 gph or a bit less. She'd fly on 3.5 gph, too, doing about 75 to 80 mph.

bnn(at)nethere.com
Guest

Posted: Mon Mar 20, 2006 7:24 am Post subject: VNE on a mod 4 1200 (was New Member)

At 05:52 AM 3/20/2006, you wrote:

 	  Quote: 	
		  Why is your VNE so much higher than mine? The red on my speedo starts at 

125. I always found it kinda scary to have a cruise speed that is only 

10mph slower than VNE.


	


Do you guys really fly around so close to Vne? (I.e. well into the yellow 

arc?) I guess you've got more guts than I do. Or do you have some 

information that says it's safe?



Thanks,

Guy

mike
Guest

Posted: Mon Mar 20, 2006 7:39 am Post subject: Re: VNE on a mod 4 1200 (was New Member)

I can't figure out what you are trying to say here.  You say you get an updraft and then your all of the sudden over VNE?  What is your cruise speed?  Are you just getting extra reading on your speed indicator that isn't reflecting on the whole airplane?  My VNE is 135 as per the short wings, medium fabric(stitched), 120 windscreen, and two weights on each aileron.  I cruise at 110 at 5200rpm IAC.  When I land I go up to 135 IAC until about 1/8 out all the time.  I don't think I've seen my airspeed jump up in turbulance, I don't stare at the guages, I'll watch the next time I get an updraft.

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Mon Mar 20, 2006 7:46 am Post subject: Re: VNE on a mod 4 1200 (was New Member)

 	  Quote: 	
		  Do you guys really fly around so close to Vne? (I.e. well into the yellow arc?) I guess you've got more guts than I do. Or do you have some information that says it's safe? 	




It's my understanding that, as long as you're flying in smooth air and you don't make any abrupt control movements, there's no danger in flying near Vne. That said, for me reach 115, I have to ajust the IVO prop for best cruise. While I can do that with a switch, I still don't bother unless it's perfectly smooth air and I'm actually going somewhere instead of just having fun.



Also, don't these numbers come with a certain amount of safety factor built in? While you don't want to excede it on purpose, Vne isn't a hard limit at which point you will abruptly loose your wings. I would not be here if that were the case.

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Mon Mar 20, 2006 7:58 am Post subject: Re: VNE on a mod 4 1200 (was New Member)

 	  Quote: 	
		  I can't figure out what you are trying to say here. You say you get an updraft and then your all of the sudden over VNE? 	




I'm mainly thinking of a cross country I did this weekend. Being a student pilot, I was probably being a bit too aggressive in my attempt to maintain the planed altitude (won't the examiner ding you if you blow it by more than 100 ft?). At one point, I entered a moderate updraft and I responded by pitching down ever so slightly to maintain altitude. Even though I was still climbing, it only took a couple of seconds for that little bit of pitch correction to add the 10 mph I needed to hit VNE. Naturally, I throttled back at that point and gave myself some breathing room but it was still scary.

mike
Guest

Posted: Mon Mar 20, 2006 8:29 am Post subject: Re: VNE on a mod 4 1200 (was New Member)

Ah! the days of flight training.  

When I started out I did it with both the cessna and the fox.  I remember my flight instructor telling me to throttle back in the fox because I was going over 5800 rpm all the time. Now days 350 hours later in the fox.  I know what it's doing without looking at the guage and do things without thinking. I guess you can always go into a slip and lower the altitude and still stay on track.

smokey_bear_40220(at)yaho
Guest

Posted: Mon Mar 20, 2006 2:09 pm Post subject: VNE on a mod 4 1200 (was New Member)

On cross countries, I find that if I want to get

better milage in my Fox, I can ride the thermals down

low and get an extra 10 mph or so.  If I get tired of

the bumps, I climb out of them.  Makes it better to

read the map.  I usually cruise at 100 mph in my S-5

in smooth or rough air.  It just rides more

comfortably at that speed.



Kurt S.  S-5



--- wingnut <wingnut(at)spamarrest.com> wrote:



 	  Quote: 	
		   > I can't figure out what you are trying to say

 here. You say you get an updraft and then your all

 of the sudden over VNE?

 

 

 I'm mainly thinking of a cross country I did this

 weekend. Being a student pilot, I was probably being

 a bit too aggressive in my attempt to maintain the

 planed altitude (won't the examiner ding you if you

 blow it by more than 100 ft?). At one point, I

 entered a moderate updraft and I responded by

 pitching down ever so slightly to maintain altitude.

 Even though I was still climbing, it only took a

 couple of seconds for that little bit of pitch

 correction to add the 10 mph I needed to hit VNE.

 Naturally, I throttled back at that point and gave

 myself some breathing room but it was still scary.

MichaelGibbs(at)cox.net
Guest

Posted: Tue Mar 21, 2006 8:33 am Post subject: VNE on a mod 4 1200 (was New Member)

Wingnut asks:



 	  Quote: 	
		  Why is your VNE so much higher than mine?


	


The older Model IVs had a 125 mph Vne.  They later increased Vne to 

140 mph on the Speedster models and the later Series 5, 6, and 7 

aircraft.



 	  Quote: 	
		  While you don't want to excede it on purpose, Vne isn't a hard limit 

at which point you will abruptly loose your wings.


	


Yes, there is some margin built in but, yes, it is a hard limit as 

far as I'm concerned.  Since you don't know what the manufacturer 

based Vne on (i.e., control surface flutter, structural integrity, 

etc.), you are definitely in test-pilot-mode if you exceed Vne.



Mike G.

N728KF

clint_bazzill(at)hotmail.
Guest

Posted: Tue Mar 21, 2006 9:20 am Post subject: VNE on a mod 4 1200 (was New Member)

The difference on the Model IV 1200 Speedster was little.  The flaperons on 

the Speedster were divided and had 2 on each.  The Long wing Model IV-1200 

had 1 on each wing, twice as heavy.  The early Speedster had split flaperons 

and then retaped.  The wind screen on the speedster was .125 inches and the 

Model IV-1200 had .093.  Above 125 mph there was a distortion of the lexan.  

I know a friend that broke at least 2 trying to install the .125 inch.  I 

put a .125 on my Model IV-1200 with no problem.  I consider my VNE 140 mph.  

Clint

From: Michael Gibbs <MichaelGibbs(at)cox.net>

Reply-To: kitfox-list(at)matronics.com

To: kitfox-list(at)matronics.com

Subject: Re: VNE on a mod 4 1200 (was New Member)

Date: Tue, 21 Mar 2006 09:33:02 -0700






Wingnut asks:



 >Why is your VNE so much higher than mine?



The older Model IVs had a 125 mph Vne.  They later increased Vne to

140 mph on the Speedster models and the later Series 5, 6, and 7

aircraft.



 >While you don't want to excede it on purpose, Vne isn't a hard limit

 >at which point you will abruptly loose your wings.



Yes, there is some margin built in but, yes, it is a hard limit as

far as I'm concerned.  Since you don't know what the manufacturer

based Vne on (i.e., control surface flutter, structural integrity,

etc.), you are definitely in test-pilot-mode if you exceed Vne.



Mike G.

N728KF

mike
Guest

Posted: Tue Mar 21, 2006 9:46 am Post subject: Re: VNE on a mod 4 1200 (was New Member)

wingnut,



another thing you might want to consider is the guages respond after things have already happened.  think of the guages hooked to the aircraft with a rubber band.  By the time the vertical speed has reacted the plane has already gone up.  So, after some time in the airplane you will feel the lift, decent, yaw, and can respond before it becomes a problem.

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Mar 21, 2006 12:03 pm Post subject: Re: VNE on a mod 4 1200 (was New Member)

Yup. I think I'm starting to get a feel for it. I had some excitement at the beginning of that same cross country when my speedo went out on takeoff. I just stayed in the pattern and tried to feel for the right airpspeed on final. I couldn't have been too far off since it was my best landing of the day and my rollout was same as usual. Pucker factor was very high so I certainly still have a long way to go  

It was just the smallest piece of what looked like tissue in th pito tube that killed my speedo. I'm thinking about ditching the little spring actuated flap for a pito cover.

-Luis

cdschieffer(at)starnetdia
Guest

Posted: Tue Mar 21, 2006 12:55 pm Post subject: VNE on a mod 4 1200 (was New Member)

With all the discussion on VNE on model IVs, I have a Model IV-1200 with a 

912uls.  The airspeed indicator is a Kitfox unit with a red line at 97 on 

the indicator.  I usually cruise about 90, could this indicator be in Knots 

or is this not the correct as indicator for this model?  I bought the a/c 

from the original builder.  I believe he started it in 92 and finished in 94 

and the serial # on the a/c is about 1811 I believe.

Chuck Schieffer

---

lcfitt(at)sbcglobal.net
Guest

Posted: Tue Mar 21, 2006 4:58 pm Post subject: VNE on a mod 4 1200 (was New Member)

Chuck,



My guess is that your ASI is in MPH.  My airplane is near your vintage and 

that is what my SS suplied ASI reads in.  A real quick check would be to use 

the calculator found at:



http://www.csgnetwork.com/tasgpscalc.html



And fly a triangle course at a  given airspeed and as instructed record the 

GPS speeds at each heading.  Take the data home and plug it into the 

calculator and you will get TAS, wind speed and direction.



The interesting part is that you only need to fly three legs at 90 degree of 

each other.



Lowell



From: "Chuck & Deanna Schieffer" <cdschieffer(at)starnetdial.net>

To: <kitfox-list(at)matronics.com>

Sent: Tuesday, March 21, 2006 12:54 PM

Subject: Re: Re: VNE on a mod 4 1200 (was New Member)

[quote] 

 <cdschieffer(at)starnetdial.net>



 With all the discussion on VNE on model IVs, I have a Model IV-1200 with a

 912uls.  The airspeed indicator is a Kitfox unit with a red line at 97 on

 the indicator.  I usually cruise about 90, could this indicator be in 

 Knots

 or is this not the correct as indicator for this model?  I bought the a/c

 from the original builder.  I believe he started it in 92 and finished in 

 94

 and the serial # on the a/c is about 1811 I believe.

 Chuck Schieffer

 ---

mike
Guest

Posted: Wed Mar 22, 2006 8:17 am Post subject: Re: VNE on a mod 4 1200 (was New Member)

wingnut,

great post.  I read all the time where pilots abort the take off when the air speed indicator is inop.  The result is usually a run off the runway and a bent plane.  Generally when I land the plane I go by feel.  Very rarely do I look at the air speed.  I make a much better landing when I fly this way, when I watch the airspeed, the landing is usually not as good.

mdps_mc(at)swoca.net
Guest

Posted: Wed Mar 22, 2006 8:49 am Post subject: VNE on a mod 4 1200 (was New Member)

There has been a few times when after takeoff I noticed that the small cover

for my pitot tube was stuck thus not allowing air flow.  This is part of my

"Pre-Flight" check list.  Flying without any measured form of airspeed will

quickly raise your awarness to the airplane, especially in landing phase.



Mike



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