This study compares the elastic properties of carbon and composite nanotubes, including BN, BC3, and BC2N, using a non-orthogonal tight-binding formalism. The results show that carbon nanotubes have a higher Young modulus than the studied composite nanotubes, comparable to defect-free graphene. The calculations agree well with experimental results. Carbon nanotubes were first discovered in the 1990s and have since attracted significant interest due to their unique properties and potential applications. Theoretical and experimental studies have shown that carbon nanotubes have exceptional mechanical properties, making them promising for composite materials. The mechanical properties of carbon nanotubes have been studied using various models, including empirical potentials and tight-binding methods. The most extensive study of elastic properties of carbon nanotubes was conducted by Lu, who used an empirical pair potential model. However, no such model exists for composite nanotubes. This study uses a non-orthogonal tight-binding scheme to calculate the structural, energetic, and mechanical properties of carbon and composite nanotubes. The results show that carbon nanotubes are stiffer than composite nanotubes, with the exception of BC2N, which is slightly stiffer than BN and BC3. The Young modulus of carbon nanotubes is in good agreement with experimental results. The study also shows that the Young modulus of carbon nanotubes depends slightly on the tube diameter, but this dependence is only noticeable for small diameters. For larger diameters, the elastic properties approach those of a flat graphene sheet. The results indicate that carbon nanotubes are stiffer than composite nanotubes, and their elastic properties are similar to those of flat sheets. BN nanotubes, while slightly less stiff than carbon nanotubes, are still considerably stiff and have an insulating character, making them suitable for applications requiring electrically insulating high-strength materials.This study compares the elastic properties of carbon and composite nanotubes, including BN, BC3, and BC2N, using a non-orthogonal tight-binding formalism. The results show that carbon nanotubes have a higher Young modulus than the studied composite nanotubes, comparable to defect-free graphene. The calculations agree well with experimental results. Carbon nanotubes were first discovered in the 1990s and have since attracted significant interest due to their unique properties and potential applications. Theoretical and experimental studies have shown that carbon nanotubes have exceptional mechanical properties, making them promising for composite materials. The mechanical properties of carbon nanotubes have been studied using various models, including empirical potentials and tight-binding methods. The most extensive study of elastic properties of carbon nanotubes was conducted by Lu, who used an empirical pair potential model. However, no such model exists for composite nanotubes. This study uses a non-orthogonal tight-binding scheme to calculate the structural, energetic, and mechanical properties of carbon and composite nanotubes. The results show that carbon nanotubes are stiffer than composite nanotubes, with the exception of BC2N, which is slightly stiffer than BN and BC3. The Young modulus of carbon nanotubes is in good agreement with experimental results. The study also shows that the Young modulus of carbon nanotubes depends slightly on the tube diameter, but this dependence is only noticeable for small diameters. For larger diameters, the elastic properties approach those of a flat graphene sheet. The results indicate that carbon nanotubes are stiffer than composite nanotubes, and their elastic properties are similar to those of flat sheets. BN nanotubes, while slightly less stiff than carbon nanotubes, are still considerably stiff and have an insulating character, making them suitable for applications requiring electrically insulating high-strength materials.