One question that comes up from time to time is how to estimate the weights of aircraft fabric finishes. I was going through my copy of K. D. Wood's Airplane Design (eighth edition, 1947), and found the following data. I thought I'd post this here for comment and reference.
Fabric and Dope
The approximate weight of fabric, tape, dope finishing material, and attaching parts as used in control surface covering varies from .070 lbs./sq. ft. of fabric area.
___________________________
Not too many people are finishing their aircraft in Grade A and dope these days, but I thought this would still serve as an interesting historical reference, one that might serve as a decent starting point for estimation.
Adding some more modern references, here are the Ceconite fabrics presented in the same format.
I haven't seen anything definitive about the weights of more modern finishes, such as Poly Fiber, Stewart, etc. I have seen comments to the effect that the total weight of all required coats wind up being roughly the same for the different systems, as there is a certain mil thickness required to fill the fabric weave and present a nice finish, regardless of the thickness of the individual coats. The assumption is that more coats of thinner dope vs. fewer coats of modern synthetic chemicals still wind up about the same mil thickness and weight in the end. I'd be interested in seeing some actual data to back that up.
__________________________________
Added 6/17/16: Poly Fiber completed weights, from Poly Fiber via Rockiedog2
Airplane Cloth, Merc. Cotton | lbs./sq. ft. |
Grade A (all but 90" widths) | .028 |
Grade A (90" widths) | .031 |
Grade B (all but 90" widths) | .031 |
Grade B (90" widths) | .033 |
Coating | lbs./sq. ft. |
Clear nitrate dope | .0052 - .0076 |
Pigmented dope | .0056 - .0083 |
Lacquers | .0056 - .0090 |
Synthetic enamels | .0049 - .0069 |
Primers | .0035 - .0069 |
Fabric and Dope
The approximate weight of fabric, tape, dope finishing material, and attaching parts as used in control surface covering varies from .070 lbs./sq. ft. of fabric area.
___________________________
Not too many people are finishing their aircraft in Grade A and dope these days, but I thought this would still serve as an interesting historical reference, one that might serve as a decent starting point for estimation.
Adding some more modern references, here are the Ceconite fabrics presented in the same format.
Ceconite fabric | lbs./sq. ft. |
102-5 (standard weight) | .019 |
101-4 (heavy duty) | .024 |
Uncertified light | .013 |
I haven't seen anything definitive about the weights of more modern finishes, such as Poly Fiber, Stewart, etc. I have seen comments to the effect that the total weight of all required coats wind up being roughly the same for the different systems, as there is a certain mil thickness required to fill the fabric weave and present a nice finish, regardless of the thickness of the individual coats. The assumption is that more coats of thinner dope vs. fewer coats of modern synthetic chemicals still wind up about the same mil thickness and weight in the end. I'd be interested in seeing some actual data to back that up.
__________________________________
Added 6/17/16: Poly Fiber completed weights, from Poly Fiber via Rockiedog2
Poly Fiber, Medium 5, fully finished | lbs./sq. ft. |
Polyspray | .063 |
Polytone | .069 |
Aerothane | .076 |
Last edited: