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Old Feb 04, 2013, 06:40 AM
rip
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United States, FL, Niceville
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Quote:
Originally Posted by jackosmeister View Post
This may help you with how it all works, wrote it a few years ago and its in need of a refresh but...

http://www.parkflyers.org.nz/modules...c_id=4&forum=3


Aeronaut Cam carbons are prefectly fine for this sort of stuff btw, and arguably perform the best, Dont worry about other flavours till your dealing with a lot more power.
Thank you very much. There is a lot of information there. I found it very useful.
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Old Feb 04, 2013, 06:41 AM
rip
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United States, FL, Niceville
Joined Jan 2013
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Propeller calculator

Found this online prop calculator. I punched in there the 10x6 prop I was talking about. There is still room for a bigger one I think.

http://www.ecalc.ch/motorcalc_e.htm?...tch=6&blades=2
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Old Feb 04, 2013, 07:39 AM
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Romania, Dolj, Craiova
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Try webocalc, will give an even more optimal answer than ecalc.
Sure, you have room up to 14" driven by a Tgy 3648 600kv motor.
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Last edited by renatoa; Feb 04, 2013 at 07:46 AM.
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Old Feb 04, 2013, 08:01 AM
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Hervey Bay, Sunny Qld, Australia
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Originally Posted by jackosmeister View Post
What glider are you refering too? A couple of kW might be fine in a good warmliner, but will destroy a thermal floater (and will weigh a lot)
Hells bells a couple of kW (kilo watts) would destroy any glider except a hotliner or F5B???
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Old Feb 04, 2013, 10:04 AM
rip
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United States, FL, Niceville
Joined Jan 2013
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Quote:
Originally Posted by ripacheco View Post
Found this online prop calculator. I punched in there the 10x6 prop I was talking about. There is still room for a bigger one I think.

http://www.ecalc.ch/motorcalc_e.htm?...tch=6&blades=2
great the changed "something" on the site the date for the data shows 2/4/2013 now a 10x6 prop is totally out of spec... humm... maybe that is not a good prop calculator ...

...BUG BUG BUG... if you click on the link it gives an error... if you re-enter all the values it works.
... BUG BUG BUG!!!

If I wans't a computer programmer... Oh well. Its free right?
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Old Feb 04, 2013, 10:18 AM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
Joined Mar 2008
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Quote:
Originally Posted by renatoa View Post
Try webocalc, will give an even more optimal answer than ecalc.
Sure, you have room up to 14" driven by a Tgy 3648 600kv motor.
The webocalc program is far less useful for glider pilots than eCalc. It is geared for power flyers and has nowhere
near the info that eCalc gives you.
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Old Feb 04, 2013, 10:38 AM
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Well, with a good understanding of theory behind, I managed to use it for many gliders too with great success.
I didn't found in eCalc yet the method how to search for an optimal, just playing endless with values until you find it. Quite groping...
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Old Feb 04, 2013, 11:09 AM
rip
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Quote:
Originally Posted by renatoa View Post
Well, with a good understanding of theory behind, I managed to use it for many gliders too with great success.
I didn't found in eCalc yet the method how to search for an optimal, just playing endless with values until you find it. Quite groping...
I see what you mean. with eCalc is a try and error. punch some numbers and expect a result. It be better if you could go backwards. Type expected results and get the input parameters.

With all this programs the variables are so many. I try to reduce variables by keeping certain thigns unchanged and try to change one variable at a time until i "get somewhere".

So far the 10x6 prop seems to be the best for the batt/esc/motor i selected before...

its long an tedious but in a weird way i enjoy it...

ecalc scorpioncalc motorcalc etc seem to be designed so that you "give it what you have... and it will tell you what it can do"
it be interesting for a program to be designed so that "you give it what you want ... and it tells you what you need to get"

man... the programmer side of me is coming out...
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Old Feb 04, 2013, 11:22 AM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
Joined Mar 2008
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Originally Posted by ripacheco View Post
I see what you mean. with eCalc is a try and error. punch some numbers and expect a result. It be better if you could go backwards. Type expected results and get the input parameters.

With all this programs the variables are so many. I try to reduce variables by keeping certain thigns unchanged and try to change one variable at a time until i "get somewhere".

So far the 10x6 prop seems to be the best for the batt/esc/motor i selected before...

its long an tedious but in a weird way i enjoy it...

ecalc scorpioncalc motorcalc etc seem to be designed so that you "give it what you have... and it will tell you what it can do"
it be interesting for a program to be designed so that "you give it what you want ... and it tells you what you need to get"

man... the programmer side of me is coming out...
Once again, Renota, is wrong, but leaving that aside, I think eCalc does what you are looking for. Want to see if you can use an 11x7 instead of that 10x6, eCalc allows you to try that out and see if you still stay in a safe range for your set up. Try Renota's suggestion (above - a motor rated at 800 watts!!!) in your program and see how many red flags you get. The options in motocalc don't even have an option for sailplanes - because it was not designed with sailplanes in mind. But, of course, feel free to try it. I'll stick with eCalc (and not the link from the Neu site) but this one http://www.ecalc.ch/motorcalc_e.htm?castle
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Old Feb 04, 2013, 11:29 AM
rip
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Originally Posted by jaizon View Post
Want to see if you can use an 11x7 instead of that 10x6, eCalc allows you to try that out and see if you still stay in a safe range for your set up...
According to e-calc and the scorpion calculator an 11x7 is out of the question. for that motor.

these work:

10x6 produces 914.7 static thrust
11x4 produces 818.1 static thrust

question is now the 10x6 may produce more static thrust but with the lower pitch of the 11x4 it may climb faster... hummm...
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Old Feb 04, 2013, 11:38 AM
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Romania, Dolj, Craiova
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The W of motors has no relevance. Is the prop who draw power, not the motor who pull it from battery.
I use it on 2 meters plane because I need anyway 200 grams in nose, lead or motor should matter ? Plus, you know how are Chinese watts rating...
I use that motor simply because there are no other smaller with this kv, simply. To avoid a gearbox.
The efficiency when turning a 14x8 does not compare with a 10x6 of a 1000kv.
Try to vertical one kg plane at 200m in 15-20 seconds drawing 15A only with other formula. No gearboxes, please.
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Last edited by renatoa; Feb 04, 2013 at 11:44 AM.
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Old Feb 04, 2013, 11:54 AM
rip
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United States, FL, Niceville
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If I must use the same motor,batt,esc ... which prop would u use? the 10x6 or the 11x4?
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Old Feb 04, 2013, 12:03 PM
rip
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United States, FL, Niceville
Joined Jan 2013
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If I reduce the voltage from 3S to 2S I can swing a 14 prop...

3S 10x6 produces 914.7 static thrust
3S 11 x4 produces 818.1 static thrust
2S 14x6 produces 721 static thrust.
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Old Feb 04, 2013, 12:12 PM
WINS - Winch In Nose Sailplane
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USA, NH
Joined Mar 2008
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Please remember - You are putting the motor in a lightweight woody, not a 2 meter hotliner.

Are you going to use this plane for ALES? Just sport flying?

In either case I think you are over thinking this problem. You don't need a rocket ship (which this plane is not). You need to get to 200m in 30 seconds.

I would give David a call at Esprit Model. (1) 321.729.4287

He is very knowledgeable and more than willing to help you out and your problem will be solved in ten minutes.

Have fun.

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Old Feb 04, 2013, 02:08 PM
Crashing into the sky!
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Auckland NZ
Joined Aug 2007
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Its easy to solve now. But thats not the point

Teach a man to Fish


I big chunk of the equation comes down to budget as well, are you happy to use HK Gear, or do you want to use higher quality gear and get a lil more bang (or less weight etc)


Personally I didnt start flying toy planes to save money
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