Recumbent - Are trikes 1/3 heavier than bikes?

Yes, it's a stupid question, and I know that the answer depends more on frame construction and materials than design. What I'm really asking is: All other things being equal (including construction materials, etc.) does adding the third wheel of a trike with its attendant frame members and axle increase the total bike weight by more or less than 33%?

Secondary question: Does the addition of the extra weight of a trike add anything to the bike other than stability at stop and during turns? It seems to me (looking at the available models on the market), that the rider's weight is much lower on a trike than on even a long-wheel-base bike. Does this really matter?

Yeah, I suppose that around 30% is about right, if you compare an average trike to an average recumbent.

Keep in mind though, that you can easily make up the difference just by riding and losing weight off the "engine!" As far as "adding" something to the trike, the extra weight is just there because it needs to be.

The low seating position of a trike makes it seem as if you're going faster than you really are. The main benefits, however, come from the extra wheel. On a trike, you won't slip and fall if you hit a patch of gravel or wet leaves. You're less likely to fall if a wheel gets stuck in a crack or train track. You can climb driveways with a 1" lip at shallow angles without worrying about your front wheel sliding out. And at stoplights, you can sit back and relax, as you wait for the light to change.