Hammerbeam Design

I have been contacted by the chair of the Millenium Project in town of Petawawa, Ontario, Canada for help with their plan. They are building a trail system in their town and want a small 10' wide Hammerbeam timberframe structure over the main entrance to the trail. They are trying to raise awareness of the history in the area. Approval has just been granted for the structure and we would like to do a demonstration at their Showcase, April 14-16 2000 to raise awareness of Timberframing and of the trail. We are contacting local sawmills to donate timbers or logs (I have a portable mill and will saw them if needed). I know this is short notice but we couldn't go ahead until we got approval.
What I need is a design and shop drawings for a frame that would be 10' wide, 8' long and a rafter rather than purlin design. I think I can cut it I just don't know how to design it! So what do you say, is there any experienced Guild member out there who will help me? Don't expect it to be free. Any help would be appreciated.

Help is on the way, sort of.

Remember that the TFG exists in part to put public projects together demonstrating the allure of timber framing (and the power of collective action).

While a hammerbeam wouldn't be my first choice, it does have a hold on the imagination, a small trail gate (reminiscent of the wythe gates in the UK) will be nice place to start.