Saturday, August 29, 2020

Pay 'n Pak Design Discussion

The brand new Pay 'n Pak turbine hydroplane rolls into the Stan Sayres Pits in Seattle, in July of 1980,
for it's christening and first test run. Photo provided by Owen E. Meaning.

From Facebook

Question: Looking at the planform of the hull here, how similar was the Pak--in its original 1980 configuration--to the '77 Blue Blaster? Obviously both were successive (Jim) Lucero designs, and you had the advantage of being involved with both of them. So aside from the obvious difference in power-plants and associated changes due to weight, how close were the two in dimension/design?

John Walters: "Length and width pretty close. Pickle fork dimensions similar. But the bottom configuration was much different. The Atlas had the break at 7 feet and almost 5 degree bottom and a slight “S.” The Pay ’n Pak had the break at 2 feet, and about a 2 ½ degree bottom with a pronounced “S.” It had a lot more bottom area with less angle of attack. And a thousand pounds lighter."

Question: Will you please explain what you mean by a "S" bottom?

John Walters: "The bottom shape was like the shape of an S. With a smoother transition at the angle change, rather than a sharp, crisp break."

Question: Where did the air go that it packed under the boat? It seems as if it packs air with no relief. Like a sheet of plywood in the back of a truck.

John Walters: "There was some room under the boat for the air to pass through. The depth of the strut was, I think, 7 inches. So the air compresses and exits under the transom. Of course some leaks out where ever it can, behind the sponsons, under the air-traps etc."

Question: (I) always assumed that those were air intakes at the front that ran along both sides of the cockpit. But never saw any other turbines with that configuration thereafter. Did they help prevent the struggles associated with salt water?

John Walters: "Yes, somewhat. The inlet configuration was similar to the Bell 214 helicopters. And an F-15."