LEADING EDGE EXTENSIONS

[EDMO 1078]

After many days (and nights) of calculations (fancy word for thinking while consuming Bud Lite) I have concluded that the simplist and lightest way to extend the leading edge about 3 to 4 inches is to make plywood ribs in front of spars terminating to a 1 1/4 (or so) aluminum tube and covering it along with the wing fabric. This should be a lot more effective / efficient than adding ballast to the tail.

When I get the prototype made I will post a photo. Then all those danged CG calculations have to be made!!!

After-all, this is experimental, just like our planes.

Feel free to say "You are nuts!", or any constructive comments will be more than welcome.

Ed in MO

[Tree top pilot 13]

For what it's worth....most of all the CG configurations I have calculated are all between 28% and 33% of MAC { Mean Aerodynamic Chord }. This is always used to get a good ballpark of where the CG would be for tapered or straight chord wings. You could make the ribs from aluminum and rivet to the LE of the spar....simple plywood rib mold and cover with .023 sheet? Sounds like a solid idea to move CG foreward.

Edited 21 Apr 2012 by Tree top pilot

[akflyer 1427]

Leading edge extentions have been used many times to offset the weight of the heavier engines. The other way people have done it is to just shorten up the front spar a tad and sweep the wings forward a bit, but I think that looks a lil goofy.

There is a model A that is sitting at the biglake airstrip I will have to take some pictures of in a couple weeks when I go up there for the crawfish boil. I bet they are 6-8" extentions and are the ugliest, flattest, most unappealing things this side of a 701! He has a VW in the nose so I know that is why he did it, but they are so sharp, the stall has to be nasty and break quick. There is a reason it is sitting there and has not moved for the 10 yrs I have known about it.

Mine has an aluminum sheet leading edge extention that sticks out about an inch or so from the front spar. There are no nose ribs in front of the spar, just the aluminum sheet bent around and glued to the spar and ribs. http://www.avidfoxflyers.com/index.php?/topic/14-my-mod-c/page__view__findpost__p__29

The pic with the wing upside down kind of shows the leading edge and will give you an idea of what it looks like. I will look on my laptop when I get out of the office and see if I have any better pictures of it.

[EDMO 1078]

Thanks for the feedbacks.

I made a rough sketch last night using an old rib. I am going back to the Harry Riblett info that Doug put in a file.

Harry had some good computer-verified info as well as dimensions. I am not changing the underside of my stol ribs. I figure that the VG additions, if needed, will take care of cruise. Harry also gave movement of Center of Lift.

I don't like the idea of drilling into my spar, so will stay with glue and wood ribs. I estimated that if I used aluminum sheet that it would add some 10 or more pounds of weight, and that is not wanted up front as that is the reason for LE extensions.

I will post more on this when I get my prototype done. I have a 3 foot old wing section to play with.

I certainly dont plan on this looking or acting hideous like the one described at Big Lake.

Sweeping the wings can cause the tips and ailerons to stall before the root - not a good idea, IMO.

Ed in MO

[EDMO 1078]

Leading edge extentions have been used many times to offset the weight of the heavier engines. The other way people have done it is to just shorten up the front spar a tad and sweep the wings forward a bit, but I think that looks a lil goofy.

There is a model A that is sitting at the biglake airstrip I will have to take some pictures of in a couple weeks when I go up there for the crawfish boil. I bet they are 6-8" extentions and are the ugliest, flattest, most unappealing things this side of a 701! He has a VW in the nose so I know that is why he did it, but they are so sharp, the stall has to be nasty and break quick. There is a reason it is sitting there and has not moved for the 10 yrs I have known about it.

Mine has an aluminum sheet leading edge extention that sticks out about an inch or so from the front spar. There are no nose ribs in front of the spar, just the aluminum sheet bent around and glued to the spar and ribs. http://www.avidfoxflyers.com/index.php?/topic/14-my-mod-c/page__view__findpost__p__29

The pic with the wing upside down kind of shows the leading edge and will give you an idea of what it looks like. I will look on my laptop when I get out of the office and see if I have any better pictures of it.

CRAWFISH BOIL? Amost missed that! Y'all some of my Coon-ass cousins? HA! Mama was Cajun - Daddy English, so I'm a half-breed, raised in the swamps.

ED in MO

[EDMO 1078]

In case someone missed it on another post: I am adding 1mm (3/64) plywood, 12 inches on top, and 6 inches on bottom of new LE so that I will have a platform for VGs later on after flight-testing.

Ed IN MO