More Prop Testing

[Drag Boat Bob]

Here are the new props that I have tested the last couple of days on my stock UL-1.

X640 - GPS: 49.3 mph. Good prop, but I prefer the Grim 38x63 (GPS: 50.2 mph)

L40x57(3): First run GPS 23.7 mph...lol. I didn't get the collet tight enough...duh.
L40x57(3): Second run GPS 50.2. Way too much cavitation. I will need to do much more sharpening (I hate sharpening 3 blades...)

L42x66: First run GPS: 50.4 mph and the boat was getting out of shape. The light wind was enough to make me let up on it or risk blowover.
L42x66: Second run GPS: 52.3 mph and the ride improved a lot by putting the batteries cross wise and all the way to the front. This run was real short due to the number of geese in the way. They are not afraid of anything.

I did add 2 additional caps to the ESC for safety before running the last two props.

I will get a few more runs on the L42x66 and the L40x57 (when I sharpen it) and then on to the m445...

[detox]

Great info...thanks!

I have also found out if you add more weight (lead weight) to the left hand side of UL-1 hull it will not chine walk as bad. This counter weights the rotation lift of prop spinning.


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[Drag Boat Bob]

Great info...thanks!

I have also found out if you add more weight (lead weight) to the left hand side of UL-1 hull it will not chine walk as bad. This counter weights the rotation lift of prop spinning.


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Would that be inside the tub or somewhere on the outside of the hull?

Also, how much weight are we talking about?

[Brushless55]

Great stuff!
what is your fav prop, and why?

[Drag Boat Bob]

Great stuff!
what is your fav prop, and why?

Well, the jury is still out on most of the later props, but of these three (38x55; 38x63; x640) I prefer the 38x63. I am an inexperienced driver and when I make too sharp of a turn and shed some speed the 38x63 accelerates well. Good hook up.

I was very surprised to see the amount of cavitation with the L40x57/3. It took too long to hook up. I am assuming that this is due to my lousy sharpening job. Time will tell...

[detox]

You can use peel and stick lead weights taped to outer left hand sponson. I believe Brain Buaas used ONE 4S LIPO BATTERY mounted inside lefthand side battery compartment when he recorded his 60 plus mph run using stock UL-1.


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[Brushless55]

is this the one?
http://www.offshoreelectrics.com/pro...od=dh-aqub9758
thanks

[Fluid]

I was very surprised to see the amount of cavitation with the L40x57/3. It took too long to hook up. I am assuming that this is due to my lousy sharpening job....

Not surprising at all. Most lifting props will cavitate some to a lot before hooking up - and some never do hook up from a dead stop. The reason is due to the lifter's wider thrust cone - lifting props push some water downwards rather than straight back, reducing thrust and causing aeration. Non-lifting props generate their thrust back to push the boat forward. But lifting props can be good, particularly on hydros. You just have to use what works with your setup, cells, etc.



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[Drag Boat Bob]

is this the one?
http://www.offshoreelectrics.com/pro...od=dh-aqub9758
thanks

Yep, dat b da one...

For me. a much better prop than the Grim L38x55. Acceleration was much better and I had absolutely no temp problems. Better top end also.

However, the L42x66 showed real promise the first time out. Too windy to try again until tomorrow... I will post results.

[Drag Boat Bob]

Not surprising at all. Most lifting props will cavitate some to a lot before hooking up - and some never do hook up from a dead stop. The reason is due to the lifter's wider thrust cone - lifting props push some water downwards rather than straight back, reducing thrust and causing aeration. Non-lifting props generate their thrust back to push the boat forward. But lifting props can be good, particularly on hydros. You just have to use what works with your setup, cells, etc.



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but.. but.. but..

with the exception of one, all of the props I tried (5) were lifter props.

However, this (L40x57) was the first 3 blade lifter and being an old boat drag racer , they will cavitate more than a 2 blade simply because the blades are closer together. Each blade needs to move beyond the previous blades "cavitation" for better bite when high rpm is involved. At least that has been my experience.

[Brushless55]

Yep, dat b da one...

For me. a much better prop than the Grim L38x55. Acceleration was much better and I had absolutely no temp problems. Better top end also.

However, the L42x66 showed real promise the first time out. Too windy to try again until tomorrow... I will post results.

Thanks Drag!
I may try that prop on my UL-1

[Fluid]

but.. but.. but...

Like I said, most lifters will cavitate some to a lot - you saw both extremes with the props you tested. But in fact the "L" Grimracer props do not have the degree of lift of more traditional lifting props like the Octura 1400 and 1700 designs. They do have more lift than "X" and "M" series props though.

For R/C drag racing, lifting props are not the ticket. When our club members were experimenting with drag racing, we found the "X" series props gave the best hole shot. Here the x-tongue was an advantage in 'grabbing' the water faster - top speed isn't an issue. The fastest accelerating rigger in the club used a 3-bladed "X" prop - nearly 80 mph in less than 200 feet. Full-scale experience does not always translate directly to models........



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[Drag Boat Bob]

Like I said, most lifters will cavitate some to a lot - you saw both extremes with the props you tested. But in fact the "L" Grimracer props do not have the degree of lift of more traditional lifting props like the Octura 1400 and 1700 designs. They do have more lift than "X" and "M" series props though.

For R/C drag racing, lifting props are not the ticket. When our club members were experimenting with drag racing, we found the "X" series props gave the best hole shot. Here the x-tongue was an advantage in 'grabbing' the water faster - top speed isn't an issue. The fastest accelerating rigger in the club used a 3-bladed "X" prop - nearly 80 mph in less than 200 feet. Full-scale experience does not always translate directly to models........



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OK, I bow to experience...

I will give the 3 blade it's due.. thanks...

[ronn25]

Drag Boat Bob those are great speeds. How is your stut setup, depth and angle? Stock turn fin? Are there any other mods?

I'm going to try a 38x63
I would be happy with 46-50mph so far I've only got 44mph with M445 prop.

[Drag Boat Bob]

Drag Boat Bob those are great speeds. How is your stut setup, depth and angle? Stock turn fin? Are there any other mods?

I'm going to try a 38x63
I would be happy with 46-50mph so far I've only got 44mph with M445 prop.

My boat is completely stock except for the addition of 2 caps to the ESC (mainly for safety reasons). I did add epoxy through the turn fin holes (with syringe) before the boat got wet.

I am using the stock water jacket, but moved the water exit tube to one of the available fittings on the top. This dropped my motor temp by 10 to 15 degrees.

The strut setting when purchased was about 7/8". I have dropped that to 1" with no other changes to angle etc.

When I finish with prop testing (I have not tested the m445 as yet) I plan to change the collet to a Kintec model and add the bearing.

I have not touched the hull, but plan on it after prop testing.