Cessna FT337GP - 3 blades prop

[n86121]

Excellent news!

As I understand it, the most efficient propellor in cruise has ONE blade, as that represents the least drag, but has terrible static thrust (will take a long time to gain speed from standstill or to climb).

There actually have been single blade balanced experimental props.

https://en.wikipedia.org/wiki/Single...e%20powerplant.

Two blades are obviously more nicely balanced, at least aesthetically.

Three blades will give more static thrust. From a standstill, able to move more air per rotation, so are able to accelerate the aircraft (or climb) a wee bit faster as they can produce more pressure. BUT, in theory, 3 blades should be slower in cruise than two, as one now has to drag three blades through the same air (rotationally).

That's why heavy turbprops will go to four blades. They can accelerate / climb the aircraft faster than fewer blades, where speed or absolute efficiency are less a priority.

That all said, I would think 3 blades dynamically balanced would tend to break up engine pulse vibrations and should result in a slightly smoother ride.

However, a good dynamically balanced prop (on the airplane) should get close to the same results.

[Alainb]

David ,
Thanks for you replay
I guess the main advantage of the three blade would be the a bit noise reduction... and here in Switzerland it would be a "plus".

I discuss with MT-Propeller and they confirm to me you could have a rear 3 blades and a front 2 blades... interesting.

On my 206 I installed a 3 blades and the noise decrease a lot.

Thanks for your returns

Alain

[mshac]

As the old saying goes, "there is nothing free in aviation." If you increase your rate of climb with three blades, you will lose cruise speed.

My 310 still has two bladed props, even though all the cool kids switched over to three blades. My reasoning is the airplane spends most of its time in cruise flight, so I choose to optimize flight in that condition. I've flown formation with similar 310's, and the two-bladed birds are consistently 3-4 knots faster at the same fuel flow settings in cruise flight.

Plus its less expensive to keep the props you've already got!

[wslade2]

How do the MT props compare in weight vs the standard props?

[Alainb]

read that
https://www.cessnaskymaster.com/props.html

[wslade2]

I knew I had read somewhere the MT props were lighter. 60lb weight savings nothing to sneeze at.