Author Topic: Undercamber props for Four Strokes (Read 700 times)

Dennis Toth · « **on:** December 08, 2022, 05:31:31 PM »

Has anyone tried running undercambered props on four strokes? It seems we would have torque to utilize the pulling power of the UC props and this would help with corners and up-top maneuvers. What have you run?

Best, DennisT

Robert Zambelli · « **Reply #1 on:** December 09, 2022, 10:04:13 AM »

Hi, Dennis.
I have not tried undercamber props but with your logic, it sounds like a great idea.
I am presently flying three airplanes with four-cycle engines, OS Surpass 26 and SAITO 30, all with Master Airscrew 9-6 plastic props (older version).
Can you suggest any suppliers of undercamber props that I can try?

Bob Z.

Dennis Toth · « **Reply #2 on:** December 09, 2022, 11:38:10 AM »

Bob,
I just take a 2" diameter piece of PVC wrapped in 120 sandpaper and just sand it into a Brodak prop, you only need about 0.015"- 0.020" more or less across the whole bottom. There may be some CF props (Bob Whitney may have something). I am planning on using a Saito 56 in a Still Victory and will start doing some bench testing after I finish my new Barnstormer. I'm thinking to start with a 13x5 maybe trim to 12 3/4 with the undercamber. The undercamber is supposed to add pull out of corners and up-top. I also want to try a balloon bladder tank to give a little more consistent fuel delivery we will see how this works.

Best, Dennis

Robert Zambelli · « **Reply #3 on:** December 09, 2022, 07:10:55 PM »

OK, Dennis, I’ll give it a try.

I have a number of SAITO 56 and 62 engines and I’ve found some interesting characteristics:
They seem to run best with 20/20 fuel, available from Powermaster.
They like muffler pressure.
The best prop I used was a Top Flite 12-6 wide blade wood. I’m sure other same size props would work well but you should experiment.
They run in all sorts of mounting positions but I was most pleased with profile mounting.
And, very important, vent the intake air to the outside for a cowled in configuration. This gives the most consistent runs.

Dennis Toth · « **Reply #4 on:** December 10, 2022, 12:07:12 PM »

Thanks Bob for the info for a starting point. I have heard that some have use the 13x5's also will see how this works out I have a few of each to try once I get the ship built. When I ran the OS 52 in my Scribe (modified Magnum) I ran 12 1/2 x6 props and it was happy so I think the Saito should be in the same range. RPM ~9200.

Attached is some information I found from an old thread on undercamber props from Brian Eather.

Best, DennisT

Author Topic: Undercamber props for Four Strokes (Read 700 times)

Dennis Toth

Undercamber props for Four Strokes

Robert Zambelli

Re: Undercamber props for Four Strokes

Dennis Toth

Re: Undercamber props for Four Strokes

Robert Zambelli

Re: Undercamber props for Four Strokes

Dennis Toth

Re: Undercamber props for Four Strokes