I replaced it with a 2 bladed prop and crashed a few seconds after taking off. I repaird he plane, put on a three bladed prop and and have flown it fine
Wings,
What you haven't told us is what other changes were made besides 2 vs 3 blades.
What was the diameter/pitch of the 2 bladed prop?
Diameter/pitch of the 3 bladed prop?
Did you get sufficient speed before pulling up elevator with the 2 blade prop?
Did the plane pull or roll to the left when you took off? (Did it drop the left wing before it hit the ground?)
There are a number of variables that could have caused you to crash with the 2 bladed prop.
I put a 2 bladed prop on and it was very unstable at lower speeds.
In your second post, this statement made me think that the pitch of the 2 bladed prop was quite a bit higher.
If you fly a high pitched prop too slowly, the blades of the prop will actually stall, just like a wing will stall if flown too slowly. If the blades of the prop stall, the prop doesn't pull the plane.
You may have been flying on the edge of a stalled prop while flying slowly.
In any case, trust the answers you've been getting. 2 blades are more efficient than 3.... All the other stuff.
Dennis-
Dennis-