Suggestions for a 3 blade prop?

[nickB722]

I'm off to the LHS now, hopefully they've got a few three bladers in stock to try out. Looking at the Grim 40x52/3 and/or a 440/3 this time around, hoping to add a x642 and getting a new m445 to replace the one I dinged up in transport a few weeks ago. I'll post results if/when I get a few good runs in.

[nickB722]

Got a Grim 40x52/3 last Thursday. Got her sharpened and balanced but didn't have a chance to run this weekend. My summer is pretty much over next weekend, so I'll have one last shot to get some real world running in. After that, the only chance of runs will be an occasional straight run in a ship model testing tank too narrow to turn in and too short to reach top speed (but data, high speed camera footage, and telemetry will make up for the lack of turning... I hope).

[nickB722]

Tonight I had a chance to run the Grim 40x52/3. I didn't have very good results as she wouldn't plane off without a huge push at the start (and fell off plane in all turns). My initial guess was that the strut was a bit too high (not enough bite on takeoff), but I'm not sure. When I was able to get the prop to hook up with a big push, it seemed to take off much faster than the stock one and threw a decent looking (low and long) roostertail. I wasn't able to adjust the strut as it was getting DARK way too fast to even bother with anything but quick CG adjustments. I'm probably out of luck till next season, but I'll do what I can to tweak when I get the chance to run.

I did get a few runs in with the stock prop for initial baseline setup/tuning/testing purposes. I was able to commandeer a laser temp gun for the night and got a good bit of data as far as heat goes. I'll have to find my notes to get the exact numbers, but I took readings on the batteries, deans plugs, motor bullets, ESC caps, and the motor itself as well as the water and air. It is my hope to get this data up here as well as adding info to it as I test different props/setups.

I was able to pick up a new M445 to replace the one lost in the sinking incident, I'll sharpen and balance it when time permits and get good temp reading samples once I get her dialed in.

Also, if anyone has had luck with the 40x52/3 I'd like to hear about strut position/angle and CG if at all possible.

[gtrcguru]

i tried a 40x52/3 and had the same results as you. the further down i moved it the better it got though.
dont really know what the angle was but i go on how high strut is in relation to strut mount.
the best run was when strut top was level to just below top strut mount. batts were center middle of batt tray. thats as far as i went with it.
ive also run a x452/3 and it seemed to plane out alot better without as much top speed but that was before it was sent to be sharpend.
im sure it will be a bit faster after its trim down

[nickB722]

Well I figure with the NiMH batteries I run I won't have to go quite that low on the prop, but I'll definitely be lowering the strut.

Were you able to eventually get her on plane and running well with the Grim prop? How were speeds compared to some other props you had on her?

Glad to hear it's more than just a few of us Michigan types screwing around with the three bladers!

[gtrcguru]

it planed out alot better with it low. it still had some run up issues but once it was on plane it flat got with the program.
i would say it was one of the fastest props ive tried but i only put a couple runs on it so i never really found its sweet spot. its out being s&b
if you do the math i think it comes out to the boat moving 3.2" per revo of the shaft. thats pretty fast as far as props go.
i like the 3 bladers because its more scale. i even ran it on my mystic. i could tell big difference on it.
still had plane issues but again once on plane you better hold on!!!
i think the 42x55/3 would be a better prop. more prop in the water which = higher strut angle & more speed.

[nickB722]

Thanks for the details/updates. I'll definitely give the adjustment a shot when I get the chance, hopefully turning it into a project for prop/powerplant matching later this semester.