Author Topic: Hypothetical Propeller Question  (Read 105 times)

dtreid

Hypothetical Propeller Question
« on: May 19, 2020, 10:18:32 PM »
Hypothetically, could I put a 3 blade H295 prop on my H391b?

Why or why not.

Louis

Re: Hypothetical Propeller Question
« Reply #1 on: May 20, 2020, 06:40:59 AM »
Why not, if it is hypothetically.  There is no STC, with means it won't be legal.   So uninsured.   Then the hub must be changed to the three blade one.  Once done, we could put the three blade on this new hub.  Total cost being hypothetically around half the value of the plane.  Or we could put some MT propeller since we don't need any STC.  Maybe change just the blades on the Hartzell hub, since they had done it before for aerobatics plane.  Or change the engine slotted shaft to a standard flange ( Lycomming did  produce that part for geared engine ) to be able to put a regular MT, so the weight of the three blade would be similar to the two blade set up.  Then we would adjust our flying technique because a three blade Helio does sink a lot more. So sometimes we do need all the power of the bigger engine to prevent from going behind the power curve on slow approach, wich was not so long ago the main reason the Helio were lost at landings.  And be careful about the delay the engine would take to obtain it's RPM since the 260 HP might be a little short to spin the three blades at an angle to produce torque.

So in reality, it's not desirable or feasible.  But hypothetically, it is quite easy to imagine.

Louis