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| prop pitch sizing ? http://ww.w.hpbc.ca/viewtopic.php?f=19&t=3263 |
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| Author: | phillnjack [ March 1st, 2016, 8:49 am ] |
| Post subject: | prop pitch sizing ? |
when most new props are now sold exactly what does the size of pitch mean . Some say that prop A is 13 x 19 so we buy the 13 diameter with its 19 pitch Yet when tried and tested it dont seem to be a 19 , it seems much more ? the tricky bit now is what is meant when then they say things like with its extra cup bla blah blah My point is simple realy. A . Is the prop a 19 With extra cup put into it ? ( making it more pitch ) or B . is it a smaller prop that with the added cup is now a 19 pitch ? |
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| Author: | OneCycle [ March 1st, 2016, 9:26 am ] |
| Post subject: | Re: prop pitch sizing ? |
your engine probably cant spin a 19. maybe go to a smaller pitch? |
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| Author: | phillnjack [ March 1st, 2016, 9:53 am ] |
| Post subject: | Re: prop pitch sizing ? |
my engine can spin a 23 pitch, but that's not what I was asking. I put a 19 pitch purely as an example for the question. I want to know if the props are what they say as in 19 pitch , or are they more due to the added cup ? if I go out today and buy a brand new 22 pitch propeller that says added cup on the box what do I get pitch wise ? |
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| Author: | OneCycle [ March 1st, 2016, 9:58 am ] |
| Post subject: | Re: prop pitch sizing ? |
out of experience with props i have added cupping to like a 29T1 yamaha prop... it lowered my rpm about 100-200 rpm at top end.. buying a brand new prop from mercury or what ever i have never seen them market "added cupping" as new. so my 29 acted a pitch bigger really. but i had it done. typically your pretty safe buying a 23 from the factory and it being in around 23 |
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| Author: | phillnjack [ March 1st, 2016, 1:34 pm ] |
| Post subject: | Re: prop pitch sizing ? |
most makes of props that have big cup seem to advertise as "added cup for extra bite" not just mercury. that's why I asked if buying a 23 would I be getting a 23 or a 23 plus extra making it like a 24. most people when asked seem to say the trophy and trophy plus in the same pitches have a difference of around 1 inch pitch when they have took them to prop shops to be measured. I am trying to buy what I need in one go, over here there is no testing of props and taking back to exchange. with props here being so expensive its not an option. I dont want to buy a 21 then find out its a 23 for instance due to being a cupped prop. |
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| Author: | OneCycle [ March 1st, 2016, 2:30 pm ] |
| Post subject: | Re: prop pitch sizing ? |
ffs.. i dont give one fuck. i'm not sure why i was commenting... maybe just to be nice..... 21 pitch is 21 pitch every prop will run different slip. so it doesn't mean a 21 pitch is a 23 it just means maybe its running lower slip numbers... Now figure it out. why do you think we all have more than one prop. |
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| Author: | BoomerMuskoka [ March 1st, 2016, 2:45 pm ] |
| Post subject: | Re: prop pitch sizing ? |
OneCycle wrote: ffs.. i dont give one fuck. i'm not sure why i was commenting... maybe just to be nice..... 21 pitch is 21 pitch every prop will run different slip. so it doesn't mean a 21 pitch is a 23 it just means maybe its running lower slip numbers... Now figure it out. why do you think we all have more than one prop. some of us have more than 10 props and still want another prop.. |
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| Author: | beavertonae-21 [ March 1st, 2016, 3:03 pm ] |
| Post subject: | Re: prop pitch sizing ? |
No two prop manufacturers make the same as advertised pitch, even two of the same props from the same manufacturer can differ a pitch or more. |
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| Author: | phillnjack [ March 1st, 2016, 3:19 pm ] |
| Post subject: | Re: prop pitch sizing ? |
thanks beavertone, that was what I was asking |
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| Author: | DoktorC [ March 1st, 2016, 3:40 pm ] |
| Post subject: | Re: prop pitch sizing ? |
beavertonae-21 wrote: No two prop manufacturers make the same as advertised pitch, even two of the same props from the same manufacturer can differ a pitch or more. More to that is the pitch is different at different spots on the blade..so pitch can end up being an "average" pitch across the blade. Added cup decreases slip but does not add pitch...but obviously that pulls RPM down versus a non-cupped version. There are MANY variables that make one prop act a certain way and another different. Like James said its why we all have a few different props and we've all gone through MANY to get to the props that suit our needs. We also have the guys from Hydromotive as members here...they may chime in and straighten us all out. |
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