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covering

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bartmo(at)sbcglobal.net
Guest

Posted: Sat Feb 02, 2008 12:53 pm Post subject: covering

I am ready to cover the fuselage on my Firestar II and undecided whether to cover the sides up to the wings or leave top part open. I would like to hear pros and cons.

  Bart

   

  Do not archive.

 [quote][b]

Lanny Fetterman

Joined: 10 Jan 2006
Posts: 37
Location: Catawissa Pa.

Posted: Sat Feb 02, 2008 1:13 pm Post subject: covering

I only covered my FSII up to the top of the fuel tanks. If you only have 

the short windshield, covering up to the wings will cause a lot of drag, I 

would think. With a full enclosure, it wouldn`t be as big of a deal. 

Covering up to the wings will make it harder to add fuel and may cause a 

problem with fumes in the cockpit. To each his own, however, I like the way 

I covered mine. My 2 cents worth. Lanny FSII  N598LF

_________________
Lanny Fetterman Firestar II N598LF

mdnanwelch7(at)hotmail.co
Guest

Posted: Sat Feb 02, 2008 1:58 pm Post subject: covering

Bart,



  I just recently covered my fuselage, and only covered up to the top of the tanks.  I am going to finish the rest of the way up to the bottom of the wings with thin Lexan.  FYI, I have a full enclosure MkIII.



  And while we're on the subject of Poly Fiber...don't forget to get the digital thermometer for monitoring the iron's surface temperature, when it comes time to shrink the fabric.  I realize there are those among us that are proficient at shrinking fabric without a digital thermometer, but in case you aren't, the fear factor is reduced with a handheld D.T.



Mike Welch  (just back from frozen wind-blown Missouri.)



Do Not Archive



________________________________



Date: Sat, 2 Feb 2008 12:49:40 -0800

From: bartmo(at)sbcglobal.net

Subject: covering

To: kolb-list(at)matronics.com

I am ready to cover the fuselage on my Firestar II and undecided whether to cover the sides up to the wings or leave top part open. I would like to hear pros and cons.



Bart



Do not archive.





_________________________________________________________________

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planecrazzzy
Guest

Posted: Sat Feb 02, 2008 2:20 pm Post subject: Re: covering

I will be enclosing the whole thing ( one of these days )



 But, till then ... This is how I did mine....



 The " Flame " cover , is Velcro'ed ....and lifts easy for refueling...



                  Gotta Fly...

                                  Mike & "Jaz" in MN



Building Buttercup...

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ElleryWeld(at)aol.com
Guest

Posted: Sat Feb 02, 2008 5:11 pm Post subject: covering

if you like to fly in cold weather you should really  give it some thought I did my firestar and it cut down on the draft on my back  

  

 Ellery in Maine 

 do not archive

  

  In a message dated 2/2/2008 3:53:55 P.M. Eastern Standard Time,  bartmo(at)sbcglobal.net writes:

  	  Quote: 	
		     I am ready to cover the fuselage on my Firestar II and undecided whether    to cover the sides up to the wings or leave top part open. I would like    to hear pros and cons.

   Bart

    

   Do not archive.

 	  Quote: 	
		  



="http://www.matronics.com/Navigator?Kolb-List">http://www.matronics.com/Navigator?Kolb-List

.matronics.com/">http://forums.matronics.com

://www.matronics.com/contribution">http://www.matronics.com/contribution



	
	




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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Mon Feb 04, 2008 7:14 am Post subject: Re: covering

 	  mdnanwelch7(at)hotmail.co wrote: 	
		  Bart,



  I just recently covered my fuselage, and only covered up to the top of the tanks.  I am going to finish the rest of the way up to the bottom of the wings with thin Lexan.  FYI, I have a full enclosure MkIII.



	




How did you enclose the back area of your MK III, the flat area in the back that faces the prop.  Can you post some pictures ? 



I have enclosed mine, but am still planning on fairing the back end with aluminum like John H did on his.   That big flat area has to be creating some drage and maybe even disturbing the airflow for the tips of the prop in that area.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

mdnanwelch7(at)hotmail.co
Guest

Posted: Mon Feb 04, 2008 8:34 am Post subject: covering

Mike,



  For the moment I just wrapped the end of the fuselage with fabric.  Since my engine/prop is removed, I don't know the clearance for building a fairing, yet.



  My intention is to build either an aluminum or fiberglass fairing, once the prop is replaced.  To be honest, I'm not real sure how much clearance there should be, between the fairing trailing edge and the prop blades.  Any recommendations, you'ze guys??



  Here's an "expertise" question for the really smart guys.  I know the conventional wisdom for building a fairing at the rear of the fuselage (the 6" wide flat area) would be to make it simetrical...in other words, just make a "vee", centered on the flat area.   BUT!!  Has anyone given any thought to off-setting the trailing edge of the fairing significantly to one edge?

  Like this artist's rendition  (ha ha):



                           I       I

                           I      I

  Fairing -->          I     I

                           I    I

                           I   I

                           I  I

                           I I

                           I



___<_____ How did you enclose the back area of your MK III, the flat area in the back that faces the prop. Can you post some pictures ?

 	  Quote: 	
		  

 I have enclosed mine, but am still planning on fairing the back end with aluminum like John H did on his. That big flat area has to be creating some drage and maybe even disturbing the airflow for the tips of the prop in that area.



 Mike


	


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mdnanwelch7(at)hotmail.co
Guest

Posted: Mon Feb 04, 2008 9:43 am Post subject: covering

Well, so much for my "artist's rendition!!  This "rich text" email style evidently doesn't allow me to type figures in a clear area of the page.  (It just slides everything over to the left.



  What I was trying to portray was a "vee" fairing that had the trailing edge even with one side...not in the center.   My thinking is, as a propeller swings close to the fairing it may slam air against one edge of the fairing.  But if one edge was canted to one side, creating a "more" sloped edge slightly ahead of the blades, it would seem to me this would be a more logical design.



Let me try to show this idea once more.  I'll use dots, to keep from having averything slide against the left.

This would be an overhead view, looking down on the propeller swinging past the fairing.



.....I.......I

.....I......I

.....I.....I

.....I....I

.....I...I

.....I..I

.....I.I

.....I

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Feb 04, 2008 9:57 am Post subject: covering

My thinking is, as a propeller swings close to the fairing it may slam air 

against one edge of the fairing.



Mike W





Mike W:



Seems like some 4130 tabs welded to the rear verical fuselage tubes would 

have been ideal for attaching a sheet metal or fiberglass fairing.  Already 

got the fabric on though.  ;-(



I had mine covered, flown 100 hours, when the fabric fairing I had 

originally designed and fabricated got beat to death by the prop.  I didn't 

have any choice but drill the vertical tubes to rivet the aluminum fairing 

in place.  Don't forget the tube seal.  Mine has performed well.



I think I would design and build the tail fairing straight.  Over the years 

I have done a lot of experimentation with stuff, attempting to overcome 

adverse yaw in the mkIII.  Of all the experiments I have done, an oversized 

rudder trim tab works best.  All the other stuff was a waste of good time 

and effort.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Mon Feb 04, 2008 10:00 am Post subject: Re: covering

Interesting idea, makes sense that there will be rotating air just in front of the prop at that point, offsetting to one side would compensate for that.  How much, it could be a lot, or barely measurable, I have no idea.   I don't know if I would want to answer all the questions about why I built the back of my airplane is " Crooked "      



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Mon Feb 04, 2008 2:03 pm Post subject: Re: covering

A question about the covered cage section:



Is the fabric wrapped around the outside of the frame and then curved around the metal tube and glued onto its backside inside the cockpit or does it only get glued to the metal tube itself? 



As far as streamlining the the cockpit, and having done actual streamlining experiments in a wind tunnel(not on a Kolb) I can make the following comments:



The streamlining behind the cockpit would be most beneficial for reducing drag and smoother airflow to the prop if it ended sharply instead of a blunt end that will create vortices.



Even offset to a sharp point would be better than straight and can be done to the side that would help counteract P-Factor a tiny bit. (Depends which way your prop is turning)



However the tip of the prop may be doing 450 mph at full throttle and at that speed the prop probably does not care much about a few small vortices, although you may reduce prop noise a tiny bit.



On the other hand streamlining behind the cockpit/seat would likely have some tangible benefits from a drag reduction point of view and just plain looks nicer.



If I was doing it I would go with the sharp point fairing behind the seat.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

azfirestar

Joined: 08 Dec 2007
Posts: 25

Posted: Mon Feb 04, 2008 9:43 pm Post subject: covering

Mike,



For aerodynamic purposes, it's best to minimize the transition angles 

that the air has to follow - if the angle is too great, the air flow 

will separate (as in wing stall) and you will loose the benefit of the 

fairing.  In the case below, the angle on the right side might be a bit 

steep, depending on how long your fairing is.  For a given length, the 

shallowest angle would be achieved by a symmetrical fairing.  When I 

worked on pneumatic aircraft systems, we tried to keep angles of sharp 

transitions (i.e. the angle from one surface to the next along a 

streamline) to less than 7 degrees, but that was probably conservative.



The prop clearance you need highly depends on the prop.  The IVO prop 

needs a lot of clearance because it flexes so much.  (I think they 

recommend at least 5").  Also, as you pointed out, the airflow near the 

prop is somewhat complicated, so I think you would want some separation 

in order to minimize vibration due to interaction of the prop and airframe.



Dan G

503 F2

Tucson



Mike Welch wrote:



 	  Quote: 	
		    What I was trying to portray was a "vee" fairing that had the trailing edge even with one side...not in the center.   My thinking is, as a propeller swings close to the fairing it may slam air against one edge of the fairing.  But if one edge was canted to one side, creating a "more" sloped edge slightly ahead of the blades, it would seem to me this would be a more logical design.



Let me try to show this idea once more.  I'll use dots, to keep from having averything slide against the left.

This would be an overhead view, looking down on the propeller swinging past the fairing.



......I.......I

......I......I

......I.....I

......I....I

......I...I

......I..I

......I.I

......I

_________________
Dan G.
503 Firestar II
Tucson AZ

mdnanwelch7(at)hotmail.co
Guest

Posted: Tue Feb 05, 2008 8:25 am Post subject: covering

Hi Dan,

  

   I'm fairly familiar with the design requirements of a smooth flowing airfoil.  Without my (Ivo)prop in place, I can't quite tell what shape that fuselage trailing edge fairing would actually be.  I think I was more musing, rather than actually suggesting a specific shape.

  

   As a propeller blade is swinging past this fairing, would there be any advantage at all if the fairing has a "more angled" edge??  I guess that would depend on the distance to the fairing and the angle it has to swing past.

  

   I just walked out to my shop and took a look at the area in question.  The aileron tube (and corresponding hardware) really interfere with the ability to buiild a very effective fairing.  Plus, the fact is you don't get much room to build something terribly fancy.  I think this is one of those cases where you do the best you can...and call it good.

  

   Now, those wing strut end-fairings Uncle Craig built....those would really be nice to have!!

  

 Mike Welch

 Building the first 200 mph MkIII (Just kidding!!)

  

  

  

 Do Not Archive

  

  

  

  

  

  

  

 > Mike,

[quote] 

 For aerodynamic purposes, it's best to minimize the transition angles 

 that the air has to follow - if the angle is too great, the air flow 

 will separate (as in wing stall) and you will loose the benefit of the 

 fairing. In the case below, the angle on the right side might be a bit 

 steep, depending on how long your fairing is. For a given length, the 

 shallowest angle would be achieved by a symmetrical fairing. When I 

 worked on pneumatic aircraft systems, we tried to keep angles of sharp 

 transitions (i.e. the angle from one surface to the next along a 

 streamline) to less than 7 degrees, but that was probably conservative.

 

 The prop clearance you need highly depends on the prop. The IVO prop 

 needs a lot of clearance because it flexes so much. (I think they 

 recommend at least 5"). Also, as you pointed out, the airflow near the 

 prop is somewhat complicated, so I think you would want some separation 

 in order to minimize vibration due to interaction of the prop and airframe.

 

 Dan G

 503 F2

 Tucson



Helping your favorite cause is as easy as instant messaging. Yoxt_hotmail_join' target='_new'>Learn more.   	  Quote: 	
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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Tue Feb 05, 2008 9:10 am Post subject: Re: covering

I wish Craig would sell the wing strut fairings, and even more so, the big engine cowl he made !!!   I would be first in line for that.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

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