Alphalpha
Well Known Member
Historically many aluminum structured aircraft have had an issue where the skins forming around nose ribs tend to form bulges. This is largely because it is very difficult to make aluminum rib nose ends with flanges that exactly form the desired shape of the nose. Most manufacturers rely on squaring it off a little short of the nose end and relying on skin rigidity to form the desired shape as it is forced around ribs.
This works with thicker materials but sometimes thinner materials have issues. We must first recognize that anytime we take a sheet and try to form it around a line of points it will both try to form or bend around the line and it will try to form around each individual point poking into it. The more elastic the material the more this latter characteristic happens. If the end has square corners then it will try to take a shortcut and form bulges around those corners while bending the span between ribs. And Van's designs have shown some propensity to do this.
It is a little bit random for a lot of reasons but even the best efforts to minimize this by reshaping the rib corners can still lead to bulge results or slightly misshapen noses.
It occurs to me that in today's world of CNC technology it would be very easy to make little nose end parts out of any HDPE plastic that form a D shape with an aft facing flange on the flat of the D to rivet or attach it to the squared off nose of the rib. This would do a better job of forcing the skin into the desired shape while "hiding" the corners from the skin bending process. RV-15 wing ribs would need left and right facing versions where the new plastic tip attach flanges attach to the rib surface opposite the direction of the flanges.
While these might be a bit of work to machine out they would be very easy and inexpensive to 3D print. The three dimensional "D" would need to be about .5" wide or deep with the material forming the cylindrical and flat portions of the letter would be about .125" thick and the aft mounting flange would also be .125" thick.
I will try to draw a picture and add it to this thread.
Something to think about.
This works with thicker materials but sometimes thinner materials have issues. We must first recognize that anytime we take a sheet and try to form it around a line of points it will both try to form or bend around the line and it will try to form around each individual point poking into it. The more elastic the material the more this latter characteristic happens. If the end has square corners then it will try to take a shortcut and form bulges around those corners while bending the span between ribs. And Van's designs have shown some propensity to do this.
It is a little bit random for a lot of reasons but even the best efforts to minimize this by reshaping the rib corners can still lead to bulge results or slightly misshapen noses.
It occurs to me that in today's world of CNC technology it would be very easy to make little nose end parts out of any HDPE plastic that form a D shape with an aft facing flange on the flat of the D to rivet or attach it to the squared off nose of the rib. This would do a better job of forcing the skin into the desired shape while "hiding" the corners from the skin bending process. RV-15 wing ribs would need left and right facing versions where the new plastic tip attach flanges attach to the rib surface opposite the direction of the flanges.
While these might be a bit of work to machine out they would be very easy and inexpensive to 3D print. The three dimensional "D" would need to be about .5" wide or deep with the material forming the cylindrical and flat portions of the letter would be about .125" thick and the aft mounting flange would also be .125" thick.
I will try to draw a picture and add it to this thread.
Something to think about.
Last edited:
