July 15, 2008 - New Tailgroup

Group,

This photograph has just arrived of the Z-21A Roundtail empennage being built by Roy Pullen. Although several of these have now been built I take the opportunity here to emphasise that the picture shows more eloquently than words how the Type 2 'square tail' structure has been adapted to the elliptical laminated profile without losing anything of the original strength. Indeed, with the integral wooden finpost and the inherent strength of the continuous curving lamination, I am convinced it is quite a bit stronger. Furthermore, the bracing wires, not shown at this stage, will greatly stiffen the whole.

This unit differs from the tail on Rupert's due to it's using a full-depth Stummelflitzer rudder (the shortened fuselages of the Stummelflitzers resulted in deeper sternposts on these types). A ventral tailbay strake will make up for the additional rudder height on the shallower tailbay and lower Z-21 sternpost. I recommend this as the most suitable and simple adaptation for the Z-21 Roundtail variant.

Perhaps some lightening holes would have been worthwhile in fabricating the horizontal tail components in this instance, especially as ounces saved at the tail end are crucial, but it's a nice piece of work, Roy.