Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Slipping with Flaps
Goto page 1, 2 Next

Matronics Email Lists Forum Index -> Kitfox-List

View previous topic :: View next topic

Author Message

chris(at)southernskies.ne
Guest

Posted: Tue Dec 16, 2008 5:09 am Post subject: Slipping with Flaps

Hello Listers,



I have a simple question:



Is it permissible to do a (hefty) forward slip with full flaps on a model 5 ?



Why do I  ask? Short field, coming in over some tall trees, trying to get down quick.  I have good roll control with flaps, just wondering about potential negative effects. 



And another question:



Due to the nose pitching down so much with flaps I have to bump the electric stabilizer trim a good bit, otherwise lots of backpressure. Now if I had to go around it would be a bit busy to adjust flaps and trim quickly while adding power, taking carb heat off and looking at trim position indicator all at the same time. Leave the flaps alone until at a reasonable altitude, then trim?



Thanks for the input, its always helpful.



Chris Bowles

KF 5

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Tue Dec 16, 2008 6:02 am Post subject: Slipping with Flaps

 	  Quote: 	
		   From: Southern Skies [chris(at)southernskies.net]

 Why do I  ask? Short field, coming in over some tall trees, trying to get down quick. 


	


I am certainly not an expert, Chris but ... why do you use the flaps at all? On my model 3, they only add a bit of lift but no drag as it is necessary to prevent picking up speed as you put the nose down after the tall trees.



One of the funniest thing I have done with my plane is the time we had a navigation contest somewhere in the mountains. To win, one had to find five objects at five locations but also land at the time we thought we would.



Since the grass airfield was at the bottom of a deep valley, as I fly toward it, I realized that I was a bit after schedule and I had to make it as soon as possible to final. Because it is legal to cross the runway centerline before turning downwind, I went right for it. But then, I had to descent perhaps a couple of thousand feet from the top of the mountain to the deep valley. So, I did it by side slipping, one way, then the other, only a hundred feet over the tree tops on the slope. It was exactly the feeling of Alpin skiing! Shuuuuus! Shuuuuuus! Shuuuuuuus! ... 



Anyway, I think that you can control pretty well any speed by only sideslipping. As you say, the pitch-down effect of flaps is ... unpleasant, to say the least.



Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200 ... flying as PAX



<pre><b><font size  color="#000000" face="courier new,courier">

_________________
Kitfox 3 - Jabiru 2200

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Tue Dec 16, 2008 6:57 am Post subject: Slipping with Flaps

.Chris,

With about 80-90' trees on  each end of my runway, I face a similar problem.

I used to head for the tops of the trees with a shallower glide slope and

then at the tree tops slip down to the runway, straighten out and land.  



I now do it quite differently, and feel it is better way to go.

Essentially, I get on the steeper glide slope immediately on final with a

medium slip.  I hold this all the way to the runway, straighten out and

land.  I can steepen the glide slope by going to a more extreme slip or

flatten out the glide slope by reducing the slip.



I feel that this is safer since I can easily avoid the tree tops if I get

hit by an increase in head wind by just reducing my slip.



Oh, back to title, slipping works great with mid position flaps. I do slip

with full flaps, but the fox just doesn't seem as happy in that

configuration.



Randy

Kitfox 5/7, 912S 776 lbs 

Warp Drive taper tip

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Tue Dec 16, 2008 8:43 am Post subject: Slipping with Flaps

But remember Michel, he's got a Model 5..isn't that a quite different  

animal than your 3?....different wing, adjustable horizontal stab, etc?



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis

do not archive



On Dec 16, 2008, at 9:01 AM, Michel Verheughe wrote:



 	  Quote: 	
		  > From: Southern Skies [chris(at)southernskies.net]

> Why do I  ask? Short field, coming in over some tall trees, trying  

> to get down quick.



 I am certainly not an expert, Chris but ... why do you use the  

 flaps at all? On my model 3, they only add a bit of lift but no  

 drag as it is necessary to prevent picking up speed as you put the  

 nose down after the tall trees.




	




 	  Quote: 	
		   Cheers,

 Michel Verheughe

 Norway

 Kitfox 3 - Jabiru 2200 ... flying as PAX



 www.matronics.com/contribution</a>

 List">http://www.matronics.com/Navigator?Kitfox-List</a>

 forums.matronics.com</a>

 </b></font></pre>

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Tue Dec 16, 2008 10:44 am Post subject: Slipping with Flaps

 	  Quote: 	
		   From: Lynn Matteson [lynnmatt(at)jps.net] 

 But remember Michel, he's got a Model 5..isn't that a quite different  

 animal than your 3?....different wing, adjustable horizontal stab, etc?


	


.. what? Different wings? I thought that we, angels, all had the same type of wings! By the way, do you think that when a bird dies, he gets ... wings? Or perhaps ... hands? Sorry, it's Chrstimas soon ... too much eggnog. You see, since I lost my driving license, there are no more reasons for me to stay sober! ... Cheers!



Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200 ... flying as PAX, even when sober



Do not archive



<pre><b><font size  color="#000000" face="courier new,courier">

_________________
Kitfox 3 - Jabiru 2200

Tom Beirne

Joined: 02 Apr 2008
Posts: 13
Location: Ireland

Posted: Tue Dec 16, 2008 1:36 pm Post subject: Re: Slipping with Flaps

 	  Michel wrote: 	
		  You see, since I lost my driving license, there are no more reasons for me to stay sober! ... Cheers!

<pre> 	


I'm glad to see that your glass is always half full (so to speak) these days

LarryM

Joined: 27 Nov 2007
Posts: 63
Location: Genoa, IL

Posted: Tue Dec 16, 2008 2:52 pm Post subject: Re: Slipping with Flaps

I'm an extreme slipper with full flaperons deployed, door open (both) or closed - no problems.



larry

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Dec 16, 2008 9:07 pm Post subject: Re: Slipping with Flaps

Michel,

I've heard this line of reasoning before but I'm always a little confused by it. If your flaps add lift then doesn't that reduce your stall speed and therefore your minimum safe approach speed? If you minimum safe approach speed is lower then your angle of descent is higher for the same sink rate right? Am I missing something? 



[quote] am certainly not an expert, Chris but ... why do you use the flaps at all? On my model 3, they only add a bit of lift but no drag as it is necessary to prevent picking up speed as you put the nose down after the tall trees.[quote]

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Wed Dec 17, 2008 12:26 am Post subject: Slipping with Flaps

 	  Quote: 	
		   From: wingnut [wingnut(at)spamarrest.com]

 If you minimum safe approach speed is lower then your angle of descent is higher 

 for the same sink rate right?


	


I don't know, Luis. Does it? ... any expert in the audience? 



Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200 ... flying as PAX



<pre><b><font size  color="#000000" face="courier new,courier">

_________________
Kitfox 3 - Jabiru 2200

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Dec 17, 2008 3:46 am Post subject: Slipping with Flaps

Certainly not me, Michel, but my flaps slow me down, and I use them  

for landing, but only halfway if the wind is a strong x-wind. Then I  

want more aileron control.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 596+ hrs

Sensenich 62x46

flying again after rebuild, and new Electroair direct-fire ignition  

system;

also building a new pair of snow skis





On Dec 17, 2008, at 3:24 AM, Michel Verheughe wrote:



 	  Quote: 	
		  > From: wingnut [wingnut(at)spamarrest.com]

> If you minimum safe approach speed is lower then your angle of  

> descent is higher

> for the same sink rate right?



 I don't know, Luis. Does it? ... any expert in the audience? 



 Cheers,

 Michel Verheughe

 Norway

 Kitfox 3 - Jabiru 2200 ... flying as PAX



 <pre><b><font size  color="#000000" face="courier new,courier">



 www.matronics.com/contribution</a>

 List">http://www.matronics.com/Navigator?Kitfox-List</a>

 forums.matronics.com</a>

 </b></font></pre>

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Wed Dec 17, 2008 5:41 am Post subject: Slipping with Flaps

Larry,

What are you flying?



Randy - Series 5/7

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

LarryM

Joined: 27 Nov 2007
Posts: 63
Location: Genoa, IL

Posted: Wed Dec 17, 2008 6:29 am Post subject: Re: Slipping with Flaps

Randy,

  i have a MK1V Avid Stol wing with a 582.

larry

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Wed Dec 17, 2008 9:57 am Post subject: Slipping with Flaps

Thanks Larry,

I just suspect that the Series 5/6/7 wing behaves differently than the

higher lift wing.



At full flaps on my 5, it takes a lot of forces to push the stick over to

slip and there is a lot of buffeting.  This isn't there at the half flaps

point.  I did put anther detent in at the 1/4 flap point when I built my

plane.  I do use that often.  It adds some lift but very little drag.



Slips are fun and very useful.



Randy

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

wingsdown(at)verizon.net
Guest

Posted: Wed Dec 17, 2008 4:32 pm Post subject: Slipping with Flaps

Not sure where I heard or who told me or maybe I just read it,  side

slips with flaps was not a good idea. I just never did them with flaps

for that reason. Maybe someone can refresh me on the why.

Rick



--

crazyivan

Joined: 25 Aug 2006
Posts: 62
Location: Pensacola

Posted: Wed Dec 17, 2008 5:16 pm Post subject: Re: Slipping with Flaps

There might be aircraft out there where the flaps blank the airflow over the tail and you lose control.   Just a theory.  But, I have never had a problem slipping my Speedster, with or without flaps.



Full flaps on my Speedster really throw the breaks out, but I lose a lot of aileron authority and get a lot of adverse yaw.  Slipping with full flaps is possible, but the rudder/aileron/elevator coordination demands a lot more attention and it's not comfortable.  Anything less than full flaps is no problem.



Forget the opinions and hearsay.  Only one way to find out.  Go up to 2500' agl, slow down to approach speeds with power off and full flaps, and kick in the most slip you or your airplane can do.   I kick a lot of rudder with the opposite wing waaaayyyy down starting at 60 mph.  I then pull the nose up a little to slow down to 50 to assure myself that I won't do a cross-control stall at my approach speeds.



I am now comfortable cutting a moderately aggressive slip on final close to the ground. 



For the academic portion of the chat, flaps increase lift, and increased lift always increases drag.  Additionally, flaps provide a nose-down pitching moment which causes you to pull more up-elevator, which increases drag as well.   Since the Kitfox is so light then a 10% increase in drag just doesn't feel like much.

_________________
Dave
Piper PA-22/20

MichaelGibbs(at)cox.net
Guest

Posted: Wed Dec 17, 2008 9:38 pm Post subject: Slipping with Flaps

Rick sez:



 	  Quote: 	
		  Not sure where I heard or who told me or maybe I just read it,  side

slips with flaps was not a good idea.


	


Cessna prohibits slips with flaps extended on the 172 and similar 

models, but this is specific to those airplanes.  Piper Cherokees can 

be slipped with full flaps with no difficulty and I had no problem 

slipping my Model IV Kitfox with flaps extended.



 	  Quote: 	
		  I just never did them with flaps for that reason. Maybe someone can 

refresh me on the why.


	


Light Cessnas exhibit some undesirable aerodynamics in that situation 

because the flaps disturb the airflow over the tail surfaces.



Mike G.

N728KF, Kitfox IV-1200 Speedster

Phoenix, AZ

LarryM

Joined: 27 Nov 2007
Posts: 63
Location: Genoa, IL

Posted: Thu Dec 18, 2008 1:07 pm Post subject: Re: Slipping with Flaps

The Cessena prohibition is only on particular models with 40 degrees of flap travel.  The models with 30 degrees are not prohibited.



  I don't think that the wing airfoil influence the ability to slip, but merely the airflow over the stab.  I would think therefore that all models of the Kitfox is ok to slip.



larry

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Thu Dec 18, 2008 3:53 pm Post subject: Slipping with Flaps

Two words... Spam Cans!  

Cessna advises in their POH not to do slips with full flaps as air coming off the wings is unsettled passing over the tail of the plane.  

Noel  

--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

wingsdown(at)verizon.net
Guest

Posted: Fri Dec 19, 2008 8:27 am Post subject: Slipping with Flaps

That  must have been it. I was flying both the fox and a 172 and it must have been the  CFI that slapped my hand in the Cessna.  Thanks

  

 Rick

 [quote]   

   --

Beemer

Joined: 26 Aug 2006
Posts: 87
Location: Middle Georgia

Posted: Fri Dec 19, 2008 12:22 pm Post subject: Slipping with Flaps

The C-172 POH for the older planes has this limitation for 40 degrees only. There is no such limitation for the newer 172 models limited to 30 degree flaps.  

   

Bradley  

           

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Rick

 Sent: Friday, December 19, 2008 11:26 AM

 To: kitfox-list(at)matronics.com

 Subject: RE: Re: Slipping with Flaps  

  

     

That must have been it. I was flying both the fox and a 172 and it must have been the CFI that slapped my hand in the Cessna.  Thanks  

    

   

    

Rick  

  [quote]  

--

_________________
Beemer
KF2 (and now an M3!)
Suzuki G10 three-banger
Middle Georgia

Display posts from previous:

	Matronics Email Lists Forum Index -> Kitfox-List	All times are GMT - 8 Hours Goto page 1, 2 Next
Page 1 of 2

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum