Everything You Wanted To Know About Electric Powered Flight
06-15-2011, 03:15 PM
#80
New Member
Join Date: Aug 2010
Posts: 9
Motocalc is very useful
I use Motocalc and find it invaluable.
When I am selecting a motor and prop combination for a particular model, I put in the model paramaters (span, area, weight, wing-shape) and will try a particular motor with 6 to 9 different props.
The table prints out with current drawn, power delivered, RPM, static Thrust, etc.
It will also print out a commentary page describing the takeoff performance and how maneuverable the plane is.
I have used it on several models to select the proper motor/prop combination for best performance.
When I am selecting a motor and prop combination for a particular model, I put in the model paramaters (span, area, weight, wing-shape) and will try a particular motor with 6 to 9 different props.
The table prints out with current drawn, power delivered, RPM, static Thrust, etc.
It will also print out a commentary page describing the takeoff performance and how maneuverable the plane is.
I have used it on several models to select the proper motor/prop combination for best performance.
06-17-2011, 11:47 AM
#81
Community Moderator
Thread Starter
Join Date: Aug 2005
Location: NY, USA
Posts: 5,873
Originally Posted by moorinee
I use Motocalc and find it invaluable.
When I am selecting a motor and prop combination for a particular model, I put in the model paramaters (span, area, weight, wing-shape) and will try a particular motor with 6 to 9 different props.
The table prints out with current drawn, power delivered, RPM, static Thrust, etc.
It will also print out a commentary page describing the takeoff performance and how maneuverable the plane is.
I have used it on several models to select the proper motor/prop combination for best performance.
When I am selecting a motor and prop combination for a particular model, I put in the model paramaters (span, area, weight, wing-shape) and will try a particular motor with 6 to 9 different props.
The table prints out with current drawn, power delivered, RPM, static Thrust, etc.
It will also print out a commentary page describing the takeoff performance and how maneuverable the plane is.
I have used it on several models to select the proper motor/prop combination for best performance.
Watts?
Flight performance?
06-17-2011, 04:49 PM
#82
New Member
Join Date: Aug 2010
Posts: 9
accuracy of motocalc
My measures that I compare Motocalc with actual results are three:
Amps delivered to ESC
Watts delivered to ESC
and Static Thrust.
I don't have a tachometer but you might want to compare those as well.
Tachs are quite inexpensive nowdays.
I measure the current and power with a "Watt's Up" power meter.
I measure the Thrust with Rapala digital scale (rather like a fish scale).
An example is that I calculated 62 amps and 725 watts for a thrust of 71 oz.
I measured 64.5 amps and 778 watts with a thrust of 73 oz.
I am pretty sure that the difference is that the program assumes the LiPo battery has 3.7 volts per cell. That is usually the voltage when I finish a flight, but I start with the cells closer to 4.2 volts per cell.
I was quite surprised and pleased to see how well the program predicts.
Elmer
Amps delivered to ESC
Watts delivered to ESC
and Static Thrust.
I don't have a tachometer but you might want to compare those as well.
Tachs are quite inexpensive nowdays.
I measure the current and power with a "Watt's Up" power meter.
I measure the Thrust with Rapala digital scale (rather like a fish scale).
An example is that I calculated 62 amps and 725 watts for a thrust of 71 oz.
I measured 64.5 amps and 778 watts with a thrust of 73 oz.
I am pretty sure that the difference is that the program assumes the LiPo battery has 3.7 volts per cell. That is usually the voltage when I finish a flight, but I start with the cells closer to 4.2 volts per cell.
I was quite surprised and pleased to see how well the program predicts.
Elmer
06-21-2011, 12:15 AM
#85
New Member
Join Date: Aug 2010
Posts: 9
wives
Hey Dimeflyer
Just tell your wife that you are going to order a computer course for men to improve your spousal interaction skills. Tell her that it is supposed to make you so much more aware of your wife's needs, and to make you more understanding. She will probably give you the money for the course right out of her grocery allowance!
Just tell your wife that you are going to order a computer course for men to improve your spousal interaction skills. Tell her that it is supposed to make you so much more aware of your wife's needs, and to make you more understanding. She will probably give you the money for the course right out of her grocery allowance!
06-21-2011, 12:22 AM
#86
Community Moderator
Thread Starter
Join Date: Aug 2005
Location: NY, USA
Posts: 5,873
Originally Posted by Dimeflyer
Verry interesting Now all I have to do is talk my wife into letting me spend the money
for the program ?!?!?!
George
for the program ?!?!?!
George
http://flbeagle.rchomepage.com/
It is not nearly as comprehensive as the programs we have been discussing but I use it often. IT is fine for some "what if" work once you figure out how to use it.
06-21-2011, 11:56 PM
#87
Member
Join Date: Apr 2010
Location: Southweastern Pa.
Posts: 799
Aeajr
I have a tugh enough time with a good program so I try to stick with the best ones
I can get ahold of !
my feebel mind doe's not work with programming things to well ,I am more of
an hands on trial and errer type for the most part but that is to expensive
thiese days so I will have to try the beg and pleed system on the wife !!
George
I have a tugh enough time with a good program so I try to stick with the best ones
I can get ahold of !
my feebel mind doe's not work with programming things to well ,I am more of
an hands on trial and errer type for the most part but that is to expensive
thiese days so I will have to try the beg and pleed system on the wife !!
George
09-03-2011, 04:13 AM
#89
Member
Join Date: Apr 2010
Location: Southweastern Pa.
Posts: 799
Mooriinee
I tyred that one to get a new routter for my wood shop so I'm out of luck this trip,
sorry I just caught your post guy ?!?!
Aeajr
I will try your leed for the program but most likely will not be able to learn how to run
it all that well -you would never know I am an electronics tech and worked on
computers for 24 years mostely PCs and and Apple PCs and have certificates for Apple and IBM and from some clone dealers ?
I did internal repair on them but only ran diagnostics programs on them from the individual companies and did not have to write or change anything on the programs to do the repairs !
George
I tyred that one to get a new routter for my wood shop so I'm out of luck this trip,
sorry I just caught your post guy ?!?!
Aeajr
I will try your leed for the program but most likely will not be able to learn how to run
it all that well -you would never know I am an electronics tech and worked on
computers for 24 years mostely PCs and and Apple PCs and have certificates for Apple and IBM and from some clone dealers ?
I did internal repair on them but only ran diagnostics programs on them from the individual companies and did not have to write or change anything on the programs to do the repairs !
George
01-17-2012, 02:40 PM
#90
Community Moderator
Thread Starter
Join Date: Aug 2005
Location: NY, USA
Posts: 5,873
SETTING GOALS
Before you can select a power system you should set a goal for what you want from the power system and the aircraft.
If this is a pylon racer, then you need speed. I don't race pylon, so I don't know how important acceleration is.
If you are flying a slow flyer then weight is very important. You need enough power to keep the plane in the air but you want everything to be light. By minimizing the draw of the power system you can reduce the size of the ESC and the battery which reduces weight.
If you are flying an e-glider for thermal duration soaring, you want to focus on climb less than speed. The goal is usually to get the glider to an altitude, say 600 feet, in an acceptable amount of time, say 30 seconds, then you power off. At that point the motor/battery become dead weight. Here you might use the "burst" values for the motor/battery as you will only run them for a very short time. You are setting up for short run climb rather than long runs. You want to minimize the aircraft's overall weight, so you are sizing to those goals.
Sometimes you have to build around the prop. Ground clearance on the runway may limit your prop size. While a hand launched plane has no prop size restraints.
Space in the aircraft can decide whether you go with an inrunner or an outrunner. That outrunner needs more room so that outer can can spin without touching anything. An inrunner can lay right against the sides of the plane as long as there is enough air flow to cool it. If you have to use an inrunner but need a large prop, then you add a gearbox.
Weight can impact your decisions. If your aircraft was designed when speed 400 or speed 600 motors were the main power plant, then going to a light brushless motor may not save you any weight. Take out a 3 ounce speed 400 and put in a 1.5 oz brushless will mean you have to add lead to balance. OR, you can look at moving the battery forward to help balance without adding weight.
Consider where you will put things in order to obtain the proper balance with the least added weight. The shape of your battery may matter a great deal. For example, you may have decided that you want to use a 3S 2500 mah pack. But they are not all the same shape. Which one will fit? Or maybe you have to change your motor choice because the battery you need to support it is too big for the plane.
The point? Think about your goals for the aircraft and the power system. You and I may have the same aircraft, but we have different ideas of how we want to fly it. We will then come up with different power systems, yet both will be right for what we want to do.
Before you can select a power system you should set a goal for what you want from the power system and the aircraft.
If this is a pylon racer, then you need speed. I don't race pylon, so I don't know how important acceleration is.
If you are flying a slow flyer then weight is very important. You need enough power to keep the plane in the air but you want everything to be light. By minimizing the draw of the power system you can reduce the size of the ESC and the battery which reduces weight.
If you are flying an e-glider for thermal duration soaring, you want to focus on climb less than speed. The goal is usually to get the glider to an altitude, say 600 feet, in an acceptable amount of time, say 30 seconds, then you power off. At that point the motor/battery become dead weight. Here you might use the "burst" values for the motor/battery as you will only run them for a very short time. You are setting up for short run climb rather than long runs. You want to minimize the aircraft's overall weight, so you are sizing to those goals.
Sometimes you have to build around the prop. Ground clearance on the runway may limit your prop size. While a hand launched plane has no prop size restraints.
Space in the aircraft can decide whether you go with an inrunner or an outrunner. That outrunner needs more room so that outer can can spin without touching anything. An inrunner can lay right against the sides of the plane as long as there is enough air flow to cool it. If you have to use an inrunner but need a large prop, then you add a gearbox.
Weight can impact your decisions. If your aircraft was designed when speed 400 or speed 600 motors were the main power plant, then going to a light brushless motor may not save you any weight. Take out a 3 ounce speed 400 and put in a 1.5 oz brushless will mean you have to add lead to balance. OR, you can look at moving the battery forward to help balance without adding weight.
Consider where you will put things in order to obtain the proper balance with the least added weight. The shape of your battery may matter a great deal. For example, you may have decided that you want to use a 3S 2500 mah pack. But they are not all the same shape. Which one will fit? Or maybe you have to change your motor choice because the battery you need to support it is too big for the plane.
The point? Think about your goals for the aircraft and the power system. You and I may have the same aircraft, but we have different ideas of how we want to fly it. We will then come up with different power systems, yet both will be right for what we want to do.
03-22-2012, 04:22 AM
#93
Member
Join Date: Mar 2012
Posts: 40
Electric RC Kindergarten
Very informative and easy to understand thread. So this question was probably answered already and I just missed it. Does the ESC plug into the receiver's battery port or the port for the throttle servo? I know, dumb question. This is my first post, I'll try to do better.
03-22-2012, 05:58 AM
#97
Super Contributor
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 8,952
Originally Posted by ChuckD
Very informative and easy to understand thread. So this question was probably answered already and I just missed it. Does the ESC plug into the receiver's battery port or the port for the throttle servo? I know, dumb question. This is my first post, I'll try to do better.
If you can grab one of those digital multimeters, you can determine a lot of stuff on these electronic systems.
First, checking resistance between all of the receivers "Black Servo Wire" connections, you will find they are all common to each other, including the receiver's battery black input wire.
Second, checking resistance between all of the receivers "Red Servo Wire" connections, you will find that they also are all common to each other, including the receivers red battery input wire.
So, as a result, you can power up your receiver and its servos by plugging in your battery into the receiver battery connector, OR any servo connector. Just don't plug it in upside down. Which is exactly what those Electronic Speed Controls (ESC)with their built in Battery Elimination Circuit (BEC) does when you plug them into the receiver's throttle servo connector.
Just be a little careful if you've got an ESC with a linear type voltage regulator for the BEC. IMHO, using this type of a linear voltage regulator on any LiPo battery of more than two cells is asking for a potential overheating of the linear regulator, its shutdown, and crash of the model.
The higher quality ESC's use a uBEC or a switching power supply type of BEC. These units are far better in supplying power to your receiver and its servos. The Castle Creations ICE series of ESC's do use a switching power supply type of BEC.
Hope that helps, take a look:
http://www.wattflyer.com/forums/showthread.php?t=52821
And
http://www.wattflyer.com/forums/showthread.php?t=63779
03-22-2012, 02:39 PM
#98
Member
Join Date: Mar 2012
Posts: 40
Thanks so much. Do have a multimeter and will start using it more. I thought the ecs must plug in as you said. It just didn't make sense to plug it into the batt slot.
Thanks for the help. Without knowing for sure, that's how I thought it must work. This stuff is so expensive I hate to just burn it up by trial and error.
Thanks for the help. Without knowing for sure, that's how I thought it must work. This stuff is so expensive I hate to just burn it up by trial and error.
