P-Limited race speeds?

[Darin Jordan]

Here is a specific question. Is the Octura M445 the prop of choice for P-Lim mono with the AQ2030 motor?

I know what people here run, even me sometimes, but the real answer to me is: IT depends on the hull (type, size, setup). LOTs of options out there. I'd consider the M445 just a starting point.

You can always bend on it a bit and get more pitch.

If not, what are the hotter alternatives?

You could put an X450/3 blade on there... THAT would get things hotter...

[T.S.Davis]

If your maintaining 37 mph in nearly a perpetual turn that's not bad for speed. If you dig into that other turd of a thread you can see low 40 averages for a whole heat. So we might be going less than 37 in a turn to average out at 40.

I've pretty much stopped using my GPS because it tells me something I don't really need to know. How does my boat perform against guys I'll race with? That's all that really matters.

Are ya have'n fun with guys going around the same speed? Then lose zero sleep over how your speeds are compare to people not on your pond.

[Darin Jordan]

If you dig into that other turd of a thread you can see low 40 averages for a whole heat.

HEY!

From that thread...

On a 1-mile course, Average Speed = Heat Time:

40 MPH = 1:30
41 MPH = 1:27.80
42 MPH = 1:25.71

37 MPH = 1:37.29

That's still a DAMNED fast 1-Mile heat time...

Maintain that, hold lane 1, race clean... You'll win more heats than you'll lose... I think I'd concentrate on handling and driving, and just leave the prop alone!

[zooma]

I know what people here run, even me sometimes, but the real answer to me is: IT depends on the hull (type, size, setup). LOTs of options out there. I'd consider the M445 just a starting point.

You can always bend on it a bit and get more pitch.

>>>>>>>>>>> Not a practical solution for the average boater. Tools? Technique? Risks? Is this what the competitive guys do? Maybe I'll eventually have to learn.


You could put an X450/3 blade on there... THAT would get things hotter...

>>>>>>>>>>> I get the message. How about an X450/one blade?

I get the feeling that I am delving into closely guarded race secrets. M445 is my starting point. I understand that going faster will put more stress on the system, eventually causing something to burn out. I could stick with same pitch ratio and dia but add a blade. I could stick with same pitch ratio and go up in dia. I could go up in pitch ratio for the same dia. However, my better judgement is to go up by .1 pitch ratio and down by 2 to 3 mm in dia, and hope to find a prop like that. And, if that works, then kick up the pitch by another .1, and so-on, until I let the smoke out.

Am I on the right track here?

[kfxguy]

Most of the time slower is faster. I taught my son this when he was racing 1/8 scale nitro cars and he became a force to be reckoned with at the local track.

[Darin Jordan]

I get the feeling that I am delving into closely guarded race secrets. M445 is my starting point.

A LOT of people run M445s. Many in our club (cold-water, Washington generally cooler environment) run some form of an X447.

The problem with asking for prop help is that there are WAY too many variables for experiences boat racers to really give you solid advice. There is some hand-on involved, and the really good ones, the ones who go pretty darned fast and seem to actually reduce amp-draw doing it, know how to bend and tweak and get the most out of a particular prop. SO, it's really hard to say "do this", when "this" is a feel thing that requires some experience to make happen.

That said, if you like the way the boat works with that M445, I might back-but it a tad to unload it a bit, bend some pitch into the trailing edge outer 30% of the blade, and cup it a bit to redirect some of the lift into thrust. The right tweaks can easily be worth 2-3mph on a given prop like that, maybe more.

But, you have to be willing to tweak.

[dethow]

Thanks. Yeah, I thought my equipment and setup were in the ball park. Don't know about current draw. I might put my Swordfish data logging ESC on it to get a reading. I am starting to wonder about the GPS readings. Our practice lake is small and we go around in a continuous circle. That might be affecting the accuracy, or even limiting the boat's top speed. We will be racing on Saturday at the big lake with a NAMBA-like course, so I will leave the GPS in the boat.

Talking about the discharge rate on your batteries, not the amp draw on the esc. This rating should be written right on your batteries. Could be 20C, 30C, 40C, or what (I think) most racers are using are 65C/130C which has a continuous 65C discharge and a 130C burst discharge.

[Doby]

Love my 30C Turnigys for P-Spec classes...all you need without wasting $$$

[zooma]

Talking about the discharge rate on your batteries, not the amp draw on the esc. This rating should be written right on your batteries. Could be 20C, 30C, 40C, or what (I think) most racers are using are 65C/130C which has a continuous 65C discharge and a 130C burst discharge.

OOPS. Brain fade. Two HK Zippy 2S 5000mah 45C 5.5 bullets in series. Theoretically capable of 5000/1000x45=225 amps. I know, budget brand.

[dethow]

Love my 30C Turnigys for P-Spec classes...all you need without wasting $$$

Hey... that's cool to know. I just assumed almost everyone was using the 65C/130C. Good to know one can still be competitive with lower 30C batteries.
Well, given what Doby said it sounds like you should be fine with your 45C batteries.

Your lower GPS speeds probably have more to do with the circle you guys are running in. I think someone else may have already said it, but you may want to try going with a lower kv motor which will give you more torque to hold a higher speed through the turns. the AQ 1800kv would help some which runs nice with a M545 prop. Or, it's been discussed in another thread that the Dynamite 1500kv is a nice option. I'm not sure what kind of prop would be best with that motor as I've never run one. But I'd assume you would probably start with an M447 for sure. ABC props are also a nice option to look as well. They offer some nice variations of size, pitch and rake. I just picked up a few variations to do some testing but haven't had a chance yet. I've heard that some of the ABCs can offer slightly better performance with slightly decreased load and amp draws.

For example:
1716-10-50 may be a good option for the AQ1800. This is a 43.2mm dia, 1.6 pitch with a 10*rake.
1815-17-45 may be another good option for the AQ1800. This is a 45.7mm dia, 1.5 pitch with a 17*rake.
1914-10-50 may be a good option for the Dyn1500. This is a 48.3mm dia, 1.4 pitch with a 10*rake.
Who knows you may be able to go larger or more pitch then this on a Dyn1500. I just don't know much about them.

Here is a link to the OSE page to find these. Steve has great explanations of what all the numbers mean.
http://www.offshoreelectrics.com/pro...ade+Propellers

And do you sharpen and balance your props? I don't know much about that stuff yet and thus have mine done by Chris (Dasboata). Dasboata is his user name here on OSE. He is really good at what he does. He can do de-tonguing, back-cuts, cupping and anything you may want along with the B/S services. You just let him know what you want and if he doesn't already have that prop in stock he'll order it up, do his thing and get it sent out typically within 7 to 10 days total. You can also send him a prop you already have for work.

[Doby]

Your lower GPS speeds probably have more to do with the circle you guys are running in..

Bingo! You guys need to find a larger body of water to do some "SAW" GPS runs.

By the way, The prop I'm using on my "fastest MC on the planet" is a X452...

[zooma]

Hey... that's cool to know. I just assumed almost everyone was using the 65C/130C. Good to know one can still be competitive with lower 30C batteries.
Well, given what Doby said it sounds like you should be fine with your 45C batteries.

Your lower GPS speeds probably have more to do with the circle you guys are running in. I think someone else may have already said it, but you may want to try going with a lower kv motor which will give you more torque to hold a higher speed through the turns. the AQ 1800kv would help some which runs nice with a M545 prop. Or, it's been discussed in another thread that the Dynamite 1500kv is a nice option. I'm not sure what kind of prop would be best with that motor as I've never run one. But I'd assume you would probably start with an M447 for sure. ABC props are also a nice option to look as well. They offer some nice variations of size, pitch and rake. I just picked up a few variations to do some testing but haven't had a chance yet. I've heard that some of the ABCs can offer slightly better performance with slightly decreased load and amp draws.

For example:
1716-10-50 may be a good option for the AQ1800. This is a 43.2mm dia, 1.6 pitch with a 10*rake.
1815-17-45 may be another good option for the AQ1800. This is a 45.7mm dia, 1.5 pitch with a 17*rake.
1914-10-50 may be a good option for the Dyn1500. This is a 48.3mm dia, 1.4 pitch with a 10*rake.
Who knows you may be able to go larger or more pitch then this on a Dyn1500. I just don't know much about them.

Here is a link to the OSE page to find these. Steve has great explanations of what all the numbers mean.
http://www.offshoreelectrics.com/pro...ade+Propellers

And do you sharpen and balance your props? I don't know much about that stuff yet and thus have mine done by Chris (Dasboata). Dasboata is his user name here on OSE. He is really good at what he does. He can do de-tonguing, back-cuts, cupping and anything you may want along with the B/S services. You just let him know what you want and if he doesn't already have that prop in stock he'll order it up, do his thing and get it sent out typically within 7 to 10 days total. You can also send him a prop you already have for work.

Interesting options. I had not thought of dropping back to 1800kv, but I am interested in those props. All my props have been S/B by a club member for a small fee. However he just stopped because he had too much of a backlog, and he was getting bigger and bigger props to do. So I will have to do my own now.

[zooma]

A LOT of people run M445s. Many in our club (cold-water, Washington generally cooler environment) run some form of an X447.

The problem with asking for prop help is that there are WAY too many variables for experiences boat racers to really give you solid advice. There is some hand-on involved, and the really good ones, the ones who go pretty darned fast and seem to actually reduce amp-draw doing it, know how to bend and tweak and get the most out of a particular prop. SO, it's really hard to say "do this", when "this" is a feel thing that requires some experience to make happen.

That said, if you like the way the boat works with that M445, I might back-but it a tad to unload it a bit, bend some pitch into the trailing edge outer 30% of the blade, and cup it a bit to redirect some of the lift into thrust. The right tweaks can easily be worth 2-3mph on a given prop like that, maybe more.

But, you have to be willing to tweak.

So, no perfect off the shelf solution. Sounds like prop rework is the order of the day for the ultimate in fine tuning. I won't have to do that to keep racing with my fellow club members. I am already doing OK in P-Lim, P and a one-design "Miss K" classic hydro class. I am just now setting up a Q mono, so I will put the tuning tips to work on that.

Thanks.

[rayzerdesigns]

1500 Mph...you got me beat!

lol 1500 kv..and I have a prop it loves..i will say its easily in 50s for 6 laps..i will get some video hopefully at legg for scale race

[Doby]

If you look at the 2:20 mark...you can she how its trimmed out for ovals.

https://www.youtube.com/watch?v=2xcBY3sqrHw