• The Biplane Forum is a large global active community of biplane builders, owners and pilots. From Pitts to Skybolts, to older barnstormers, all types are welcome. In addition to our active community, our content boasts exhaustive technical information which is often sought after for projects and maintenance. This information has accumulated over the 12+ years the forum has been in existence.

    The Biplane Forum is a private community. Subscriptions are only $49.99/year or $6.99/month to gain access to this great community and unmatched source of information not found anywhere else on the web. We are also a great resource for non biplane users, since many GA aircraft are built the same way (fabric and tube construction). Annual membership also comes with two BiplaneForum.com decals.

Upper Wing III

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Creator of this place
Staff member
Jan 1, 2006
Reaction score
Austin, TX

<TD vAlign=top>Adding a piece...

Normally the trailing edge ends at that tail rib, but I unfortunately cut my trailing edge short! So I have trimmed it to end at the first main rib. To remedy this, I was going to span the remaining gap to the tail rib with spruce, and shape it to match. As luck woud have it, I stumbled across a trailing edge drop-off in the parts-bin from when I built the lower wings last year :0) Amazingly I got this piece to line-up first time.


I clearcoated the inside area where the foam was to be placed. While the second coat was wet, I pushed in the foam blocks I had trimmed ready, the clearcoat acts as an adhesive for the foam. Over all of this will be Superfil instead of the usual fibreglass. I tried fibreglass matting on the lower wing tips and made a mess of it, the supefil is a reasonable alternative, maybe not as tough as FB, but when finished laterwith clearcoat, it's pretty tough.

All drag block holeswere syringed and soaked with clearcoat using a pipe cleaner, reamed out, then the process repeated the next day. I die'd one end of each wire, placed in situ to mark off the other end then die'd it accordingly. Square 4130 .125 plate washers I had made were used instead of regular washers due to potential 'cupping' of the softer washers. In hindsight, the amount of torque applied to the wires i don't think warrants these robust washers. If I built another plane, I would simply double-up the regular washers.

Next, I marked out my trammel points at the compression rib stations, my trammel bar is advance technology: alength of 2x1 with nails in it ;-)

Drag /anti drag wires

First, I unclamped the wing from the jigs so the wing was 'free'. Working from inboard out, torqueing was done with a 'touchyfeely' type of approach. I hand tightened the nuts with maximum effort, then used a wrench for about 3/4 to 1 full turn, this moves the trammel point a little. Then went to the opposite wire and did the same, trammelling again to move the trammel point back, at the same timetapping boththe wires at the cross-over pointwith a kitchen fork in order to achieve the same audiblepitch [equal tension is of course the objective].

Plastic tubing was then added as a friction/shim sleeve to the wiresat the cross-over points, tied together withtie-wraps. I left the wing to sitovernight to 'settle' with these new pressures added to it, then tramelled again for good measure.


Trammelling the wing...

Latest posts