Mike,
One thing you need to consider for the SA 72 is the very peaky torque curve of the 72. Unlike the SA 56 which has a very flat torque curve over a large RPM range the SA 72 is strong but peaks over a narrow RPM range. You may want to consider a medium thickness airfoil (say 18 - 20%) and a lighter wing load say 12.5 lbs/sqft to allow the engine to better control speed.

Best,        DennisT

Rich,
hmmmm...  You're mentioning sub-700 sq.in. designs.  I'm using Saito 62 for those, and it pulls well.
My gut tells me that I would need to load the 72 with something bigger, at least Strega-size or larger?  But then again, I have never ventured into that territory...

I got a Saito 72 for my b-day.  Haven't run it yet, but I expect it to swing a 14-6 prop.

What would be the target wing area for this beast?  I believe in thick, blunt airfoils, moderate wing loadings, and flying 5.1 sec laps on full length lines.  Traditional flapped layout.

I'm thinking around 740 squares.

Opinions?

Mike,
This is the plane I'm currently flying with, which I designed specifically for the Saito 72. Here are the specs:

Engine: Saito .72
Model weight: 65 oz.
Wing area: 685 square inches.
Line lenght: 68.6 feet (center to center)
Prop: Top Flite Power Point 14"x6" (stock) or Rev-Up 14"x6".
Glow plug: OS type "F"
Carb: Saito modified CL carburetor as per Bob Reeve's instructions.
Fuel: 10% nitro - 20% oil (70% synthetic-30% castor)
Fuel tank: 6 oz. plastic non uniflow. (with no muffler pressure).
Fuel consumption: 3.5 oz for a 6' 30" flight.
Ground rpm's: 8.4/8.5 K with the Top Flite prop and 8.8K with the Rev-Up prop.
Lap time: 5.1/5.2

The plane flies just GREAT and the engine not only gives me the kind of power I need to fly in pretty high wind conditions, but also rock solid consistent runs in every single flight, even in hot humid days.
It works for me.

Claudio.

Thanks, Brad.
That's my own wing...certainly nothing special. NACA 0023 airfoil.

Hey Claudio:    Beautiful plane..
What if anything would you change on this design if using a Saito 62 instead of the 72 ?  
Maybe a little longer nose ?   The 62 I have weights 15.3 oz. with muffler.

Hey Claudo:    Beautiful plane..
What if anything would you change on this design if using a Saito 62 instead of the 72 ? 
Maybe a little longer nose ?   The 62 I have weights 15.3 oz. with muffler.

Hi Allan...thanks.
Yes, maybe a tad longer nose, say 1/2"-3/4", but keep the tail feathers light anyway.
The rest is OK. This plane flies REALLY nice. It is a truly competitive design, properly trimmed.
You know...PRACTICE is all it takes...

Mike,
One thing to keep in mind is that the ship doesn't need to be really big, the advantage of the BIG BLOCK is pulling power. Many people are using 90's in what use to be 60 size ships. If the ship is to big it also has more weight and pull. In normal conditions it is controllable but when the wind comes up you have a lot more sail for the wind to push and pull goes through the roof. With the big block in a smallish ship it can control wind up and pull through up top. Also you should test a smaller diameter three blade to keep the corner reasonably crisp.

Best,          DennisT