Determining Correct 3-Bladed Propeller For OS 55AX Engine
03-10-2024, 12:21 PM
#1
Thread Starter
Determining Correct 3-Bladed Propeller For OS 55AX Engine
Hello OS Manufacturing Representative,
I have one of your 55AX engines in an Ultra-Stick 60 airplane and a 12 X 6 APC propeller pulls it nicely. I've decided to use the same model engine in a 58" Wingspan Corsair kitted by Phoenix Model, however, for the Corsair I would like to use the largest 3-Bladed propeller that would be the equivalent of the 12 X 6 that I use on the Ultra-Stick. I would think I would go down in pitch when I go up in prop diameter, but not sure. Can you recommend a 3-Bladed propeller size and pitch that I can use on the 55AX Engine?
Thank you.
From Mike D'Amico
West Melbourne, Florida
I have one of your 55AX engines in an Ultra-Stick 60 airplane and a 12 X 6 APC propeller pulls it nicely. I've decided to use the same model engine in a 58" Wingspan Corsair kitted by Phoenix Model, however, for the Corsair I would like to use the largest 3-Bladed propeller that would be the equivalent of the 12 X 6 that I use on the Ultra-Stick. I would think I would go down in pitch when I go up in prop diameter, but not sure. Can you recommend a 3-Bladed propeller size and pitch that I can use on the 55AX Engine?
Thank you.
From Mike D'Amico
West Melbourne, Florida
03-10-2024, 02:49 PM
#2
My Feedback: (3)
Hello OS Manufacturing Representative,
I have one of your 55AX engines in an Ultra-Stick 60 airplane and a 12 X 6 APC propeller pulls it nicely. I've decided to use the same model engine in a 58" Wingspan Corsair kitted by Phoenix Model, however, for the Corsair I would like to use the largest 3-Bladed propeller that would be the equivalent of the 12 X 6 that I use on the Ultra-Stick. I would think I would go down in pitch when I go up in prop diameter, but not sure. Can you recommend a 3-Bladed propeller size and pitch that I can use on the 55AX Engine?
Thank you.
From Mike D'Amico
West Melbourne, Florida
I have one of your 55AX engines in an Ultra-Stick 60 airplane and a 12 X 6 APC propeller pulls it nicely. I've decided to use the same model engine in a 58" Wingspan Corsair kitted by Phoenix Model, however, for the Corsair I would like to use the largest 3-Bladed propeller that would be the equivalent of the 12 X 6 that I use on the Ultra-Stick. I would think I would go down in pitch when I go up in prop diameter, but not sure. Can you recommend a 3-Bladed propeller size and pitch that I can use on the 55AX Engine?
Thank you.
From Mike D'Amico
West Melbourne, Florida
04-14-2024, 02:19 AM
#3
Now search that same propcalculator for a 2-bladed prop that absorbs as close as possible to 2/3rd of that power at the same RPM. That is the size of 3-bladed prop you are looking for.
If APC is the brand to go for, indeed an 11 x 6 would be very close to an APC 2-bladed 12 x 6. Slightly heavier.
However, a Master Airscrew for example, would need to be 11 x 7 in order to be equivalent to a 2-bladed APC 12 x 6.
When going from 2-bladed to 3 bladed, it is always advisable to select a prop with a bit more pitch, the higher velocity of the propwash compensates a bit for the narrower diameter of that propwash, and flight performance will be more similar. At least, that is my experience.
04-14-2024, 06:38 AM
#4
If I understand the OP correctly, he wants to go UP in diameter. I'm not sure he can go up but if he stays the same diameter, he should use a 12x4 or 12x5 3-bladed prop. I had a similar issue with a 43 inch Corsair. The reason the Corsair had the inverted gull wing was to have the largest diameter prop for that huge engine. I used an OS 32SX which had very high RPM. It would swing a 10x6 2-bladed prop at around 18K RPM. So I put a 10x4 3-bladed. It swung that at 18 as well. I would like to have had a bigger prop but couldn't find one.
