UNDERCAMBERED RIB MODIFICATIONS

[EDMO 1078]

Believe I have figured out how to modify the undercambered ribs to get close to Harry Riblett's modifications. If anyone needs info, I will try to provide it.

The problem with his drawing is getting the bolt into the strut attachment after modifying - Think I have solved this problem.

If anyone is re-doing an old set of wings, and want the speed of the Kitfox 4, then this should help. I lessens the downsweep at the trailing edge too.

Read the info that Doug posted in "files" first.

I don't have photos yet, and it may be a while - still having shoulder pains, and work on my extended leading edge on 2nd wing is going slow.

EDMO

[FoxDB 17]

I am interested in this rib mod. Have you made much progress?

Dave

Mod 1 Kitfox

[Mendlerr 4]

Allanseye.  A new member here just purchased an Avid, a very early model.  He came and looked at my Kitfox IV before he purchased his.  The builder did something very interesting.  He did not reduce the undercamber but instead covered the entire top of the wing in a very very thin sheet of aluminum then wrapped it all in fabric.  Apparently his Avid is cruising at 85-90mph which rivals my Kitfox IV.  The entire top of the wing is completely smooth.  He may have stumbled on something here

 

Just thought I would share, thought it was very interesting

Edited 30 Jul 2013 by RMendler

[SuberAvid 617]

Believe I have figured out how to modify the undercambered ribs to get close to Harry Riblett's modifications. If anyone needs info, I will try to provide it.

The problem with his drawing is getting the bolt into the strut attachment after modifying - Think I have solved this problem.

If anyone is re-doing an old set of wings, and want the speed of the Kitfox 4, then this should help. I lessens the downsweep at the trailing edge too.

Read the info that Doug posted in "files" first.

I don't have photos yet, and it may be a while - still having shoulder pains, and work on my extended leading edge on 2nd wing is going slow.

EDMO

 

 

Ed, I'm interested in what you have come up with.  I think I might take the undercamber out of the HH ribs when I build my new extended wings.  I was thinking I might be able to cut a foam filler piece to fill under each rib and a new 1/8" plywood cap strip all glued to the under side of the existing rib.  Just need to figure out the correct foam and compatible glue to use.

 

Can you or Doug lead me to the post Doug did on the Riblett rib again; I don't see it in the "Files"

 

Thanks much!

[EDMO 1078]

Ed, I'm interested in what you have come up with.  I think I might take the undercamber out of the HH ribs when I build my new extended wings.  I was thinking I might be able to cut a foam filler piece to fill under each rib and a new 1/8" plywood cap strip all glued to the under side of the existing rib.  Just need to figure out the correct foam and compatible glue to use.

 

Can you or Doug lead me to the post Doug did on the Riblett rib again; I don't see it in the "Files"

 

Thanks much!

The Riblett mod is in "files and forms" or something like that, and is labeled "VGs under.....?", or something like that - scroll all the way down past the 2 cycle and 4 cycle engine sections.

Riblett gave drawing and dimensions, and said to use aluminum cap and fill with instant foam - I am using 1/8 wood caps with 2 small wood spacers at the proper points for support and debating on how much of a mess I can make with a can of foam? Looks like my finished rib will have a little more lift at the 30-35% point than the Kitfox 4 rib that I have a drawing of. Even if you make a straight line from front spar to rear spar to get rid of some of the undercamber should help, but not as much.

I found that there may be a slight problem with the rear jury strut bolt if I build too much there - And, maybe with the rear strut attachment - and I have to cut the lower rear cap off behind the spar and bring the new cap to a point about 1 1/2 to 2 inches short of where the original trailing edge is located, to get rid of the undercamber and pitching moment there.

I am still trying to finish my 4 inch leading edge covering on the 2nd wing, and it may be another 2 weeks or more before that is done - I am running out of 9460 and Kitfox is at Oshkosh.

If you need more info, or a better explanation or photos, I will be happy to supply when I can.

Randy, I copied the info from Riblett and enlarged it on my printer so I could read and compare with what I have now.

I sent you a PM about what material you mounted your boat seats on, and maybe how - haven't got an answer yet.

EDMO

Added: At some point, you have to decide whether to modify your butt and root ribs - This looks like a possible high-lift point and possible drag point if not changed?

With so much washout, I don't think the tip ribs would make much difference???

Edited 1 Aug 2013 by Ed In Missouri

[EDMO 1078]

Allanseye.  A new member here just purchased an Avid, a very early model.  He came and looked at my Kitfox IV before he purchased his.  The builder did something very interesting.  He did not reduce the undercamber but instead covered the entire top of the wing in a very very thin sheet of aluminum then wrapped it all in fabric.  Apparently his Avid is cruising at 85-90mph which rivals my Kitfox IV.  The entire top of the wing is completely smooth.  He may have stumbled on something here

 

Just thought I would share, thought it was very interesting

Anything we hear is interesting Richard,

Riblett was talking about the bubble formed in the undercamber causing drag - Guess we are all looking for the extra 10 mph, or, the ultimate 125 mph cruise....I would have used wood instead of aluminum, and that is what I did for the top 12 inches and bottom 6 inches of my new leading edge.

Wood doesn't dent like aluminum.

EDMO

[EDMO 1078]

I am interested in this rib mod. Have you made much progress?

Dave

Mod 1 Kitfox

I can post some kind of photo comparing a Kitfox 4 rib drawing to a KF 1 rib if that will help anyone - That's all I have right now to compare with the Riblett drawings.

EDMO