LEADING EDGE EXT PHOTO

[EDMO 1078]

Attachment photo came out blank - will try again when daughter comes home tonight.

Inital setup for 3 3/4 inch LE extension - more ribs to add + plywood.

ED in MO

Edited 20 Jun 2012 by Ed In Missouri

[EDMO 1078]

Puter Dummy got Photos added - see original post.

ED in MO

[dholly 718]

Hi Ed- Are you modeling the ordinates of any particular NACA airfoil? What do you think the overall weight gain will be?

[EDMO 1078]

Hi Ed- Are you modeling the ordinates of any particular NACA airfoil? What do you think the overall weight gain will be?

 

 

Doug, I just copied the profile of the original rib on top, blending it down from 2 1/2 inch spar to 1 1/4 leading edge which is near the profile of the plastic KF leading edge I removed, except 3 inches longer. 

 Will do some weight calculations and post them later on.(probably 10 lbs total, but that is optimistic?) Whatever it is, will be better than adding 50 lbs or more to tail to make up for my Soob with redrive.

ED in MO

NOTE: This is real close to Harry Ribletts recommendations and drawing of Eppler rib modifications that you posted.

The .035w 1.25 tubes weigh about 4 lbs for 26 feet. The plywood another 6 lbs, but that could be left off. Maqybe another 2 lbs for ribs and glue. I dont have any idea of what the extra fabric and paint will add. This adds 8 SF to my wing area, if I have figured it right.

Edited 20 Jul 2017 by EDMO

[EDMO 1078]

Hi Ed- Are you modeling the ordinates of any particular NACA airfoil? What do you think the overall weight gain will be?

 

 

Doug, After some thought, I'm worried about having a break in the airflow over the spanwise ridge when using 12 inches of plywood on top of wings, so will plan to only add about 6 inches of wood on both top and bottam of leading edge. This should take a couple of pounds off of mod, to get back to 10 lbs or less for leading edge extensions.   ED in MO

Edited 20 Jul 2017 by EDMO

[dholly 718]

Well, I know the aluminum sheet used on the Avid Mk-IV's extended back quite a bit. Not sure if it was 12", but it definitely was more than 6" (see edit).

I was intrigued to see what appear to be two 13gal. wing tanks in the same wing. I know the top lengthwise stringer does not pass through the Kitfox (Skystar) slip-in tanks, and you must omit the root end drag tubes when using the one tank as originally designed by the manufacturer. Seems to me then, that you must have removed even more of the spar-to-spar drag tubes to fit the second tank. If I got that right, are you concerned at all with the structural integrity of the wing without the drag tube support?

[edit] A pic attached for your pleasure.

Edited 28 Jun 2012 by dholly

[EDMO 1078]

Well, I know the aluminum sheet used on the Avid Mk-IV's extended back quite a bit. Not sure if it was 12", but it definitely was more than 6" (see edit).

I was intrigued to see what appear to be two 13gal. wing tanks in the same wing. I know the top lengthwise stringer does not pass through the Kitfox (Skystar) slip-in tanks, and you must omit the root end drag tubes when using the one tank as originally designed by the manufacturer. Seems to me then, that you must have removed even more of the spar-to-spar drag tubes to fit the second tank. If I got that right, are you concerned at all with the structural integrity of the wing without the drag tube support?

[edit] A pic attached for your pleasure.

The aluminum in the photo certainly looks longer than 12 inches - Looks like it goes over the hump (highest negative pressure area), but my 12 inch plywood would end before the hump. (Remember I extended LE nearly 4 inches). Just want to error on the safe side and not disrupt airflow on top and cause premature stalling. Yes, I know that is what VGs are for!

I still have 2 drag tubes, and believe the stiff fiberglas tanks will make the wing more ridgid than a 1/2 inch aluminum tube about 3 feet long. If the tanks were aluminum, I would possibly run a drag tube thru the outer one. The first 5 Kifoxes were sold without any drag tubes, and did not hear of a failure. But the engineer who made Denny put them in told me that some were needed. I feel safe with mine, or I wouldn't fly it.

The Kitfox has the stiffest, strongest, heaviest spars and ribs of any small plane I have ever worked on. It is super-strong compared to the wobbly spars and paper thin aluminum ribs of a J3 cub which really needs the drag tubes to keep the wing from falling apart.

The second tank in each wing can only be filled for solo flight. I originally built this to fly around Alaska - probably wont need them much down here, unless I want to go north in the summer and south in winter.

Appreciate your comments. Thanks

ED in MO

Edited 28 Jun 2012 by Ed In Missouri

[EDMO 1078]

Just adding note to update this old thread:   I did not keep the undercambered ribs, but added plywood and capstrip on both top and bottom to make them a modified Riblett profile.  15" chord separate 6+' Flaps and 6' Differential Ailerons with separate simple push-pull tube controls.  I have to measure to be exact, but should have about 160 sq.ft. wing area.  Some photos have been posted either in Kitfox IV, FOXY FLAPPER FOTOS, or in Kitfox Ribs.   EDMO 

Edited 5 Dec 2017 by EDMO