[gbanger]

I thought I would start a new thread for people who have questions or need advice on which prop they should be using in specific applications.
So I'll be the bunny...
Steve
Can you post a link for the site where you get your mega pitch props from.
I need a 13 x 12 or better prop for my PC9 upgrade, the only ones I can find are from Esprit model in the USA, they do an Aeronaut Cam 13 x 12 for $12 which is a pretty good price but I would rather get one local if I can. I would like a 13 x 14 but as far as I can asertain they dont exist. I would really like to use a 14 x 12 but ground clearance negates that option, I am already tearing the tips off my 13 x 8's at Area 51.
So after I put the big Hacker in the best thing I can find to give me warp drive performance is the 13 x 12
Gazz

--- Kieran Edit ---
Here is a list of prop relevant links and sources:
Prop/Amps Calculator
http://www.ecalc.ch/motorcalc_e.htm?ecalc

Official APC Props shop
http://www.apcprop.com/v/index.html

Hard to get and high quality glider props
http://www.flyelectric.com

Large range of props (Some not found at Hobbyking)
http://www.leaderhobby.com/list.asp?type=categories&categories=11

[secant0give]

Just a thaught Gazz,
you could lengthen the landing gear a little to give more ground clearance

leaderhobby has a pretty good selection of props but I'm not sure they will have exactly what your after but it worth a look. their prices are pretty good I get most of my wooden props from here

https://www.leaderhobby.com/list.asp?type=ALL&categories=54

[gbanger]

Thanks for the link Jason, but I don't want to reinvent the wheel, I am very happy with the current airframe setup, I have done the sums and a 13 x 12 will give me awesome performance but the motor will still be working well within itself. A 13 x 14 would stretch its legs just that little bit more.
I will probably order a couple of 13 x 12's. The performance upgrade should be pretty spectacular.
I am currently running 13 x 8 on 5S at 670kv with the Power 46, the Hacker is a lot lower kv only 425, but it can spin a 16 x 8 at 6S so with a 13 x 12 it will rip a hole in the space time continuem
The simple equation I use to compare thrust is
Eflite Power 46:- 670kv x 5S x 8 pitch = 26800
Hacker 50-14S:- 425kv x 6S x 12 pitch =30600
The final figure doesn't have a specific value but it gives you a realistic percentage of thrust difference, which should be about 15 percent.
I could always just run the Power 46 on 6S like Kev but then you are dicing with a melt down every time you take off and just I'm not a big fan of waiting till my plane turns into a fireball.

[kizza42]

I can hear your PC9 crying out for a proper 4 blade prop

[smuzz]

(Warning: Maths = ON)

Gazz - I think those calculations you've got there are speed calculations (kind-of) as opposed to thrust calculations.
You've got ...

rpm per volt x number of cells x pitch in inches

... if you modify it a little ...

rpm per volt x number of cells x 3.7 volts x pitch in inches = speed in inches per minute
rpm per volt x number of cells x 3.7 volts x pitch in inches x 0.000947 = speed in miles per hour

So Hacker 50-14S:- 425kv x 6S x 3.7 x 12 x 0.000947 = 107.2 miles per hour

This calculation is over-optimistic though because the 425kV figure is only for no-load (as soon as you put a prop on, the rate of increase in rpm per volt drops below 425 and it drops differing amounts for different props), the cell voltage drops anyway and the prop never actually acquires its true pitch speed because of the drag of the rest of the plane, amongst other things.

But, your comparison formulas are not bad as a guesstimate (the fact you haven't got the cell voltage in there doesn't matter if you're doing a comparison) - probably much more useful to get the percentage differences as you're doing, than trying to estimate absolute speeds or thrusts or whatevers ... Sorry mate - I couldn't help myself.
(Maths = OFF)

All that crap aside - I think Kieran is probably right too!

[samste]

WARNING WARNING PLEASE KEEP THE FOLLOWING INFORMATION TOP SECRET.
THE FOLLOWING WEBSITE SELLS HIGH PITCHED APC PROPS FOR THE INSANE RC FLYER.

USE EXTREME CAUTION WHEN PURCHASING AS YOU MAY BE TRACKED DOWN AS A INSANE SPEEDSTER RC FLIER AND SENT TO A REHAB INSTITUTE.

IF THIS HASN'T SCARED YOU THEN THE LINK IS BELOW




























































































































































ARE YOU SURE YOU WANT TO ?, IF SO THEN KEEP SCROLLING












































































































































































LAST CHANCE YOU KNOW FLYING WILL NEVER BE THE SAME ONCE YOU GO FAST















































































































































































































YOU MADE IT YOU CRAZY PERSON, JOIN THE SPEED CLUB


http://www.lowpricerc.com/advanced_searc...ywords=apc

[gbanger]

I agree Kieran.
I have been trying to find a decent 3 blader but the best I could find was a 13 x 8. I'm already running a 2 blade 13 x 8 so that wont help with top end, it will just bite the air a bit better and give me better acceleration.
If anyone knows where I can get a 4 blade prop about 12 x 12 then let me know.

[kizza42]

Congrats Stephen, you set off the spamming alarm

[samste]

here are some sane sites

http://rcflyer.com.au/shop/catalog/advan...ywords=apc&osCsid=29401b92a3467a8c7bcc624427925ddf

http://www.xc-rc.com.au/index.php?main_page=index&cPath=108&zenid=c5623a874f26ef5397c6552c704e7148

Steve

[Drew]

I think the prop for the HK MX2 is a three blade 12x9.

[popeyepete]

I agree Kieran.
I have been trying to find a decent 3 blader but the best I could find was a 13 x 8. I'm already running a 2 blade 13 x 8 so that wont help with top end, it will just bite the air a bit better and give me better acceleration.
If anyone knows where I can get a 4 blade prop about 12 x 12 then let me know.

Whilst Googling, this is the only site i found who make 4 blades less than 15".
http://www.zingerpropeller.com/4_bladed_propeller.htm

Otherwise APC start at 15"

[secant0give]

I think the most efficient prop is going to be a 2 blader.
There were people playing around with single blade props to go realy fast.
If speed is your need then multi blade is probably not the best way to get it.

I don't see any reason why you couldn't carve your own wooden 2 blader with the steep pitch your after. I've got a couple of nice peices or cedar you welcome too if you want to have a go.

[gbanger]

Thanks for your help team. I really do appreciate it.
I have found exactly what I need, cheers.
Gazz

[samste]

Hi Guys I'm going to do an order For some Props in the next couple of days
so anyone wanting props please let me know before then.

Gazz i have put your props in shopping cart already with the props i getting, i will just wait a couple of days to see if anyone else wants some props.

Here is the link again guys

http://www.lowpricerc.com/advanced_searc...ywords=apc