Which direction for tissue covering.

[gravitywell]

I always put my tissue on wings going from root to tip to avoid sagging between ribs, but which direction for covering fuselages?  Does one cover with the grain going from tail to nose, or from top to bottom?  Enquiring minds want to know!

[calgoddard]

I understand that the conventional technique, when covering balsa wood model airplanes with Esaki tissue or other tissue with a grain, is to orient the tissue so that its grain extends spanwise on the wing and stab, and lengthwise on the fuselage.

[OZPAF]

My understanding is similar to calgoddards for most applications, and is my memory of a similar question raised years ago on the old HPA. However there may be instances where it can be an advantage to change the orientation.

I believe the main reason for having the grain of the tissue running along the span and lengthwise of the fuselage is that this the direction of maximum strength of the tissue.

However maximum shrinkage occurs at right angles to the grain.

This is particularly noticeable on wings where the span wise hollows between the ribs is increased withe grain running span wise. Changing the grain to a chord wise direction would reduce the wing strength span wise compared to the recommended grain direction, despite providing a more accurate wing profile.

As mentioned there may be areas where changing the grain may help - say for example wing tips or fairing the fuselage covering into the fin where strength, is not so important and the extra shrinkage may produce a better finish.

Hope this helps.

John

[gravitywell]

Thanks guys....really appreciate the advice.  I guess I was doing it right!  Sometimes I amaze myself. LOL