Grumman F6F Hellcat: Cowl Ordinates:
I may have been a tad over-optimistic in my previous article on the F6F ordinates when I mentioned there was a good chance the Grumman ordinate data would be complete. The one exception is the cowl, although there is an ordinate drawing for the cowl the table itself is just a black blob, completely illegible. However, I checked the part drawings that make up the cowl which is quite well detailed so I made a start on the nose spinner ring.
The spinner ring main model is fine and here it is derived into the air scoop construction model. The construction requires numerous contour lines as each ordinate needs to be manually checked due to the poor quality of the original Grumman drawing scan.
This ordinate drawing is not deliberately blurred by me, this is how it actually looks like. The main dimension is almost legible just the fractions that are problematic. The process will require evaluating each contour line and curvature check, both horizontal and vertical as shown in the above image.
I am hopeful of achieving a good result with this model which will probably take a few days to complete.
Update 27th August:
I have now determined the correct ordinates for each of the seven profiles. Notice the lower profiles have been artificially extended to the center ring, which will give me better results when lofting. After lofting a surface the plan then is to remove the mouth of the air scoop (blue) and apply the finishing flange to the inner edge.
The ordinates are recorded in a spreadsheet with the x,y,z coordinates extrapolated as I previously did for the wings and fuselage.
Update: 12 Sept 2018:
Cowl Ring Cowl Nose setout dimensions verified.
Ordinate Dataset Completed: Wings, Fuselage and Front Air Scoop.
The F6F archive of scanned Grumman documents comprises over 7000 drawings in PDF.
Aviation CAD TechNotes 